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Ahmed F Zobaa
Junwei Cao Editors
Energy
Internet
Systems and Applications

Ahmed F Zobaa • Junwei Cao
Editors
Energy Internet
Systems and Applications
123

Editors
Ahmed F Zobaa
College of Engineering, Design,
and Physical Sciences
Brunel University London
Uxbridge, Middlesex, UK
Junwei Cao
Tsinghua University
Beijing, China
ISBN 978-3-030-45452-4 ISBN 978-3-030-45453-1 (eBook)
https://doi.org/10.1007/978-3-030-45453-1
© Springer Nature Switzerland AG 2020
This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part
of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,
recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission
or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar
methodology now known or hereafter developed.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this
publication does not imply, even in the absence of a specific statement, that such names are exempt from
the relevant protective laws and regulations and therefore free for general use.
The publisher, the authors and the editors are safe to assume that the advice and information in this
book are believed to be true and accurate at the date of publication. Neither the publisher nor the
authors or the editors give a warranty, express or implied, with respect to the material contained herein or
for any errors or omissions that may have been made. The publisher remains neutral with regard to
jurisdictional claims in published maps and institutional affiliations.
This Springer imprint is published by the registered company Springer Nature Switzerland AG
The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Contents
Part I Architecture and Design of Energy Internet
1 Foundation and Background for Energy Internet Simulation . . . . . 3
Shuqing Zhang, Shaopu Tang, Peter Breuhaus, Zhen Peng,
and Weijie Zhang
2 Modelling, Simulation and Analysis . . . . . . . . . . . . . . . . . . . . . . . . 33
Shuqing Zhang, Peter Breuhaus, Shaopu Tang, Zhen Peng,
Xianfa Hu, Ning Liu, Yaping Zhu, and Jinxin Liu
3 Cyber-Physical System Security . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Heping Jia, Yi Ding, Yishuang Hu, and Yonghua Song
4 Early Experience of the Energy Internet: A Review
of Demonstrations and Pilot Applications in Europe. . . . . . . . . . . . 121
Shi You and Hanmin Cai
Part II Energy Switching and Routing for Energy Internet
5 Modiﬁed P&O Approach Based Detection of the Optimal
Power-Speed Curve for MPPT of Wind Turbines . . . . . . . . . . . . . 137
Liuying Li, Yaxing Ren, Jian Chen, Kai Shi, and Lin Jiang
6 Flexible Substation and Its Demonstration Project . . . . . . . . . . . . . 157
Zhanfeng Deng, Jun Ge, Guoliang Zhao, and Chaobo Dai
7 Energy “Routers”, “Computers” and “Protocols” . . . . . . . . . . . . . 193
Chuantong Hao, Yuchao Qin, and Haochen Hua
8 Two-Stage Optimization Strategies for Integrating Electric
Vehicles in the Energy Internet . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
William Infante, Jin Ma, Xiaoqing Han, Wei Li,
and Albert Y. Zomaya
v

Part III Information and Communication for Energy Internet
9 Key Data-Driven Technologies in the Energy Internet . . . . . . . . . . 241
Ting Yang, Yuqin Niu, and Haibo Pen
10 Utilization of Big Data in Energy Internet Infrastructure . . . . . . . . 297
Songpu Ai, Chunming Rong, and Junwei Cao
11 Artiﬁcial Intelligence Models Used for Prediction
in the Energy Internet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
Cristina Heghedus and Chunming Rong
Part IV Energy Management Systems for Energy Internet
12 Multiple Source-Load-Storage Cooperative Optimization
of Energy Management for Energy Local Area
Network Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355
Tao Zhang, Fuxing Zhang, Hongtao Lei, Rui Wang, Kaiwen Li,
Yang Chen, and Yonghua Gui
13 Power Quality and Power Experience . . . . . . . . . . . . . . . . . . . . . . . 381
Jie Yang and Haochen Hua
14 Power Restoration Approach for Resilient Active Distribution
Networks in the Presence of a Large-Scale Power Blackout . . . . . . 397
Chunqiu Xia, Qiang Yang, Le Jiang, Leijiao Ge, Wei Li,
and Albert Y. Zomaya
15 Internet Thinking for Layered Energy Infrastructure . . . . . . . . . . 421
Haochen Hua, Chuantong Hao, and Yuchao Qin
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439
vi Contents

Part I
Architecture and Design of Energy
Internet

Chapter 1
Foundation and Background for Energy
Internet Simulation
Shuqing Zhang, Shaopu Tang, Peter Breuhaus, Zhen Peng,
and Weijie Zhang
Abstract The energy internet has been proposed and utilized to alleviate existing
environment, sustainability, efficiency and security problems and satisfy increas-
ing energy demand in energy applications, by coupling the energy flows of various
energy types with information flow. The energy internet mainly involves the energy
flow systems of various energy types and is an energy-coupling system composed
of a physical energy system and corresponding controllers. Then, using an in-depth
study of dynamic processes and the interaction among energy production, transmis-
sion and consumption, this chapter concludes that the design, planning, operation
and control of the energy internet rely heavily on analytical tools. Next, the major
components, the architecture, and the technical characteristics of the energy inter-
net are described from the perspective of simulation. Finally, application scenarios
for dynamic simulation of the energy internet and the existing simulation technical
foundation for various energy types are introduced.
S. Zhang (B) · S. Tang · Z. Peng · W. Zhang
Tsinghua University, Beijing, China
e-mail: zsq@mail.tsinghua.edu.cn; zsq@tsinghua.edu.cn
S. Tang
e-mail: tsp1988@mail.tsinghua.edu.cn
Z. Peng
e-mail: pengzhenctgu@sina.cn
W. Zhang
e-mail: 459592598@qq.com
P. Breuhaus
IRIS, Stavanger, Norway
e-mail: pebr@norceresearch.no
© Springer Nature Switzerland AG 2020
A. F. Zobaa and J. Cao (eds.), Energy Internet,
https://doi.org/10.1007/978-3-030-45453-1_1
3

4 S. Zhang et al.
1.1 Concept, Components, Structure and Characteristics
of the Energy Internet
This sub-chapter briefly describes the definition of the energy internet, provides a
brief analysis of the composition and classification of the energy internet from the
view of simulation and considers the coupling relationships between various energy
sources and related equipment in the system from a microcosmic point of view.
1.1.1 Concept and Main Body of the Energy Internet
The energy internet is a multi-energy system based on a power system or a smart
grid and is designed to fully utilize renewable energy and promote comprehensive
energy efficiency. In addition, advanced information and communication technology
and power electronics technology are employed to improve the system performance
and energy quality, as shown in Fig. 1.1. Through a distributed intelligent energy
management system (IEMS), wide-area coordinated control of distributed energy
equipment is implemented to realize the complementarity of cold, heat, gas, water,
electricity and other energy sources and to establish safe, intelligent and efficient
energy systems.
Fig. 1.1 Energy internet

1 Foundation and Background for Energy Internet Simulation 5
The National Development and Reform Commission of China and the National
Energy Administration of China summarized two modes of energy internet systems:
regional and wide-area. This book focuses on the regional energy internet.
To meet the demands of customers according to local geography and natural
features, an energy internet system cooperatively utilizes traditional and renewable
energy; optimizes the facilities of an integrated energy internet system; and takes
advantage of distributed resources, combined cooling, heating and power (CCHP)
and smart micro-grids (MGs) to realize hierarchical utilization of various kinds of
energy.
Additionally, the energy internet takes advantage of large power plants, where
different kinds of energy are combined and energy of multiple forms are generated.
In the future, it seems that distributed gas stations, which can reduce the influence of
the intermittence of renewable energy, will contribute as reserves after the intercon-
nection of various forms of energy. Moreover, electric vehicles also support energy
internet systems.
In the future, more coupling of electrical power systems and thermal power sys-
tems will emerge with the high penetration of low-carbon emission techniques, which
leaves more degrees of freedom for system planning and dispatch optimization.
Conversely, the complexity of system topology will create new challenges in con-
trol and protection. Additionally, dynamic characteristics also need to be redefined.
Therefore, modelling and simulation of energy internet systems are required [1].
The energy internet is the main link in an energy flow system that contains a
coupling transformation among at least three different forms of energy: electrical
energy, thermal energy and chemical energy, as shown in Fig. 1.1. Based on the tra-
ditional power grid and an MG, the energy internet expands and brings in new energy
sources, power electronic devices, thermal systems and gas systems and includes the
conversion, transmission, storage, distribution and consumption of various energy
types. Additionally, it involves energy device design and manufacturing, system con-
struction, control and system operation. Due to the differences in energy types of
different regions, the forms of energy internet also vary. Figure 1.2 shows a typical
energy internet.
As proposed above, the energy internet is a new concept. At present, most research
ontheenergyinternethasconcentratedonsystemdesignandplanning,whicharecon-
strained by static characteristics, and research on the dynamic processes of the system
is still in the preliminary stages. From the perspective of the system dynamic analysis
and simulation in the energy field, research on the energy internet has mainly focused
on energy flows, which involve coupled electricity, cold/heat and fuel networks, the
dynamic energy transformation among the electrical power system, renewable energy
sources, the thermodynamic system and chemical fuel pipelines, and system-level
and equipment-level control. The dynamic processes of components, devices and
networks in response to system control, faults and disturbances, and performance
tests are concerns in dynamic simulations.

6 S. Zhang et al.
Fig. 1.2 A typical energy internet system structure
1.1.2 Backbone and Main Components of a Typical Energy
Internet
1.1.2.1 Categories of Key Techniques
The energy internet involves and employs various techniques. Generally, the key
techniques can be summarized in the following categories.
(1) According to the Energy Source
The energy flows in the system take different forms, so devices dealing with different
forms of energy can be separated. Thus, the techniques can be sorted into renewable,
electrical, chemical and thermal techniques. In this case, researchers may look for
the diverse features of different forms of energy:
• Renewable sources (including solar, wind and tidal power);
• Electrical power (devices such as electrical storage, electric vehicles and heat
pumps);
• Chemical sources (including natural gas, diesel, coal, biomass, nuclear, etc.);
• Thermal sources (including solar heat, thermal/cooling storage, hot water, steam,
etc.)
(2) According to Energy Production
A special feature of an energy internet system is that grids of various forms of energy
are interconnected to form a system that can produce energies of specific forms to
meet various demands:

• Electricity,
• Heat,
• Cool,
• Chemical fuels.
Furthermore, CHP and CCHP can provide more than one form of energy, and the
combined systems are always more efficient.
(3) According to the Prime Mover
The energy internet system is based on an electrical power system that is connected to
a thermal system through prime movers, so the combined system can also be divided
by the prime mover:
• Turbines: micro-turbines, gas turbines (GTs), steam turbines, internal combustion
engines and combined-cycle gas turbines.
• Reciprocating internal combustion engines.
• New emerging techniques: fuel cells, stirling engines, and the organic Rankine
cycle.
(4) According to the Energy Sequence
Due to the location of the system, the energy sequence can be determined by the
local energy structure and categorized into the following:
• Topping cycle system,
• Bottoming cycle system.
In a topping cycle system, electrical power is the priority production and is widely
used as a common operation condition. Thermal energy is the major production in a
bottoming cycle system. In this case, the system supplies an industry that requires a
very large thermal demand.
(5) According to Scale
The scale of energy internet systems is varying. Generally, these systems can be
separated into micro-systems, regional systems and large systems. Moreover, they
can also be classified into distributed systems and centralized systems [2].
1.1.2.2 Backbone and Main Components
Interconnected energy internet grids and the corresponding control system constitute
the backbone of the energy internet.

8 S. Zhang et al.
(1) Electrical energy
• Generator
Electrical energy, as a secondary energy source, originates from different forms of
energy and different energy conversion equipment. Most of this energy source comes
from generators, which are driven by mechanical energy and realize direct energy
conversion.Withthedevelopmentoftechnology,thetypesofgeneratorshavebecome
diversified, such as micro-gas turbine power generation, wind power generation, pho-
tothermal power generation, biomass power generation and tidal power generation,
and some energy is directly generated by energy conversion equipment, such as solar
panels that directly convert solar energy into electricity and fuel cells in which the
chemical energy stored in fuel is directly converted into electricity. Due to the dif-
ferent features of primary energy sources, electrical energy production varies greatly
from daytime to evening and from summer to winter. Power generation devices have
different capacities, voltages and frequencies, and most of them are distributed. All
of these factors make the characteristics of the energy internet complex. In addition,
the combined use of multiple power sources can improve the system performance,
such as wind and solar complementarity, which can make the power supply more
reliable, and fuel cell and micro-gas turbine combined power generation, which can
improve efficiency.
• Flexible alternating current transmission system (FACTS) device and con-
verter
The electrical power from generators is transmitted to alternating current (AC) and
direct current (DC) MGs and then distributed to users through the power grid, distri-
bution transformers and converters. Converters are mainly power electronic devices.
Because electrical voltage and frequency vary among different power sources, they
must be transformed into consistent AC or DC power through power electronic
devices to be sent to a unified MG. The characteristics and control of power electronic
devices have a considerable influence on the performance of power grids.
• Electrical power load
In addition to conventional power loads, there are also new types of loads and loads
coupled with different forms of energy in the energy internet, such as charging piles
and stations for electric vehicles, heat pumps, inverter air conditioners and electrical
conversion devices. Charging piles and stations for vehicles have a considerable
impact on the power grid and other energy sources.
• Electrical energy storage
Electrical energy storage plays an important role in the energy internet. When there
is surplus energy generation, the storage devices can store it, and when the energy
generation is insufficient, the storage devices can output electrical energy as sources.
Energy storage supports the operation of the energy internet with high penetration

of renewable energy and improves the flexibility and reliability of system operation.
There are several main types of electrical energy storage devices, such as electro-
chemical energy storage, mechanical energy storage and electromagnetic energy
storage. At present, mature devices are mainly based on batteries.
(2) Thermal energy
• Prime mover
As a linkage between an electrical power system and thermal network, a prime
mover plays a significant role in the energy internet system. For this reason, it is
necessary to analyse the characteristics of prime movers. To date, several types of
prime movers have been applied in the energy internet, including micro-turbines,
gas turbines, steam turbines, combined-cycle gas turbines, reciprocating internal
combustion engines, Stirling engines, fuel cells and the organic Rankine cycle. They
have been modelled, and some typical examples have been given [3–11].
Steam turbines are widely used in the energy internet and are also one of the
oldest typical prime movers. The history of steam turbines traces back to 100 years
ago. In addition, the Rankine cycle is the principle of thermodynamic models of
steam turbines. There are two kinds of steam turbines, backpressure and extraction-
condensing, and researchers need to choose according to heat quality, the quantity
of power and heat, and economy.
• Thermally activated technologies
The key to distinguishing CCHP from other traditional combined heat and power
(CHP) technologies is that CCHP not only produces heating and power but also
cooling capacity because of cooling or dehumidification components. During the
cooling procedure, thermally activated technologies, which are involved in the cool-
ing or dehumidification components, are triggered. Evidence from recent studies has
inferred that thermally activated technologies can improve total efficiency, which
makes them popular. In addition, thermally activated technologies also satisfy low
emissions and cost reductions [12–16].
• Thermal energy storage (TES)
The different energy production of thermal system devices and electrical power gen-
erators gives a time difference between the peak demands. The unsynchronized peak
demand allows the energy internet system to reduce the net peak demand by suitably
using diversity. TES, as a reserve and heat recovery device, is competent for decou-
pling generation and demand [17]. Thus, TES not only improves the discontinuity of
the energy internet system but also lengthens the operating time. Moreover, it may
also defer investment.
The duration of the storage cycle is determined both by the load demand and
by the storage mechanisms. Practical heat storage normally involves liquid tanks.
Future heat storage will employ phase change materials (PCM) that can achieve high
energy densities; thermochemical materials; and nanometre materials.

10 S. Zhang et al.
(3) Gas energy
Natural gas is one of the most significant chemical energy types in the energy internet.
Gas energy systems usually consist of starting stations, gas pipelines, intermediate
pressure stations and gas distribution stations.
The main tasks of a starting station are to keep the gas transmission pressure
stable, automatically adjust the gas pressure, measure the gas flow and remove the
droplets and solid impurities in fuel gas.
Intermediate pressure stations are an important part of a gas network and should
be installed every certain distance in gas energy systems. The number of intermediate
pressure stations and the outlet pressure should be determined through technical and
economic calculations.
A gas distribution station is located at the end of a long pipeline and is the gas
source for a small city or industrial gas distribution network. The distribution station
receives gas from the long-distance pipeline. After dust extraction and pressure reg-
ulation, the gas purity and pressure meet the requirements of an urban distribution
ring network or industrial pipeline network.
The main task of gas storage and distribution stations is to make gas pipelines and
networks preserve the required pressure and maintain a balance between gas supply
and consumption according to the instructions of the gas dispatching centre.
In dynamic simulations, a gas energy system mainly includes pipelines, compres-
sors and networks.
1.1.3 Basic Structure of the Energy Internet
In the energy internet, power energy is transformed from renewable energy by
wind/photovoltaic power generation, and a power network is coupled with a thermal
energy network by steam turbines, gas turbines and electrical heating equipment,
and is coupled with a chemical energy network by biomass power generation, fossil
energy power generation and electrical hydrogen generation.
Due to variations in climate and energy types among different regions, there are
some differences in composition among energy internet systems. However, the main
structure of the energy internet remains similar. As shown in Fig. 1.2, the energy
internet mainly contains networks with at least three different forms of energy: a
power grid (containing AC and DC networks), a thermal system and a chemical fuel
pipeline grid, through which energy interactions among various energy devices can
be established.
In the energy internet, an electrical power grid containing renewable power gen-
eration is coupled with a thermal system by synchronous generators, gas turbines
and electrical heating equipment, and coupled with a chemical fuel pipeline grid by
biomass power generation, fossil energy power generation and electrical hydrogen
generation. The thermal system is coupled with the chemical fuel pipeline grid by
boilers.

Fig. 1.3 Typical structure of a multi-energy flow system
The structure of the energy internet mainly reflects the energy links and
interactions among energy systems, as shown in Fig. 1.3.
The electrical power grid, thermal system and chemical fuel pipeline grid indi-
vidually form their own networks. These networks are coupled through several key
devices (energy conversion devices), including micro-turbines, boilers and air con-
ditioners. Each kind of key device has its own dynamic response characteristics and
corresponding time constants. When the networks are coupled through these devices
and a dynamic excitation occurs in any network, the dynamic processes are filtered
by the key devices before they penetrate other networks. Therefore, studying the
dynamic response characteristics of key coupling devices is essential for studying
the cross-energy-coupling problem in energy internet systems.
1.1.4 Technical Characteristics
1.1.4.1 Wide Time Scale Characteristics
Existingresearchhassummarizedtherangeoftheresponsetimeconstantfordynamic
devices in a conventional power system, an MG with interference and control inter-
vention. By omitting the rapid and detailed physical processes of some device levels,
e.g. the switching transient process of power electronic devices, we can summarize

12 S. Zhang et al.
the physical processes involved in electrical energy under disturbances and their con-
trol intervention, and we can approximately divide the response time into a transient
scale from microseconds to several seconds and a medium- to long-term scale from
tens of seconds to tens of minutes. With further supplementation of the time scales
of the dynamic and transient processes of heat and fuel pipeline network equipment,
we can obtain the dynamic, transient and long-term dynamic ranges of the response
time constant for a typical energy internet system, as shown in Fig. 1.4.
The results of an induction [18–21] show that the response time span of all devices
in the energy internet is very wide, from the microsecond level in the electromagnetic
transient of the high-frequency switching circuit in a power system converter to
dozens of minutes to several hours for the heat exchange in the thermodynamic
system. Overall, the response time constants of dynamic devices and the components
of electrical energy, thermal energy and chemical energy overlap in two scopes:
• For the time scale from several seconds to a couple of minutes, the physical pro-
cesses involve the generator motive, speed-regulating device, generator mechani-
cal inertia, protection and restriction on the overheating of the equipment, action of
Fig. 1.4 Wide time scale dynamics of an energy internet system

the mechanical switch, automatic generation control, and transient load shedding.
The middle and long processes of the system involve the start-up of the micro-gas
turbine and the boiler dynamics in the thermal system. The heat exchange process
between the heat storage and the heat exchanger involves the dynamic process of
the fuel supply for the fuel network.
• The time scale ranging from tens of minutes to several hours mainly involves load
adjustment and operational intervention processes in power and thermal systems.
Coupling of equipment for the same form of energy is not difficult to understand,
and coupling among different types of energy systems and equipment in the above
two time scales is further explored in the following ways:
• The electrical power grid, thermal system and gas pipeline network are tightly
coupled on the source side. A part of the thermal energy of the boiler and micro-
gas turbine rotates the turbine to drive the generator to produce electricity, and
the other part of the thermal energy enters the heating, cooling or storage of the
thermal network.
• Thermoelectric, fuel cell and other power generation devices are coupled on the
fuel supply side, and these devices are coupled with the power grid and the heating
network.
• The above two forms of coupling are in a time scale from several seconds to a
few minutes and belong to coupling of fast processes.
• The coupling between thermal power and the power network belongs to the cou-
pling of slow processes in the scale from tens of minutes to several hours caused
by the change in thermal and electrical load power.
Thecouplingofanenergyinternetsysteminawidetimescalecreatesdifficultiesin
solving simulation models. Generally, a small step is fundamental to solving devices
and subsystems containing fast dynamics to ensure convergence and accuracy of the
algorithm. For a power system with small time scale dynamics, calculation of the
device and component models requires dozens of microseconds or even smaller step
sizes.Ifthemathematicalmodelofthewholesystemissolvedbythesamesteplength,
the computational burden increases significantly, the whole simulation decelerates
and the scale of simulation is limited. If a multistep approach is adopted, stable,
accurate and fast, numerical algorithms are necessary to guarantee the accuracy and
validity of the model solution.
1.1.4.2 Fundamental Differences in Modelling and Solving for Various
Forms of Energy
1. Modelling and calculation of coupling among equipment and between
equipment and networks
There are essential differences in the coupling mechanisms within energy grids,
and different modelling and calculation methods of coupling among equipment and

14 S. Zhang et al.
between equipment and networks pose difficulties to dynamic simulation of the
energy internet. Specifically, there are several cases as follows.
The main body of the electrical power system is basically composed of gen-
erators with exciters and speed regulators, transmission and distribution networks,
power electronic devices and loads. The grid is the coupling link among equipment
components of the electrical power system. In electromagnetic and electromechan-
ical transient simulations, the device elements are also coupled with the grid and
incorporated into a whole grid through the “component-network interface”, realizing
simultaneous solution of the equipment and power grid models. Taking a generator
as an example, the terminal voltage and current are transformed and connected to the
network equation in synchronous rotating coordinate and solved together. The rotor
angle is used for the interface between the electric quantity in the dq coordinates of
the generator and the electric quantity in the synchronous coordinates of the network
in the xy coordinates.
In comparison, the scale of the thermodynamic system is relatively small, the
number of equipment components is limited, and the coupling among equipment
components is more direct. In the simulation, dynamic models of components and
devices are joined by associated equations or associated parameters.
Different coupling methods among components and between systems and com-
ponents lead to differences in model solution algorithms. In each time step of the
simulation, each component and the dynamic element model in the electrical power
grid are separately solved, and then all the models of components and dynamic
elements are solved jointly through the component–network interface. For the ther-
modynamic system, the models of each component and dynamic component are
directly connected to form a higher dimensional model group, and the whole system
is solved simultaneously.
2. Strong non-linear algebraic equations
Dynamic models of an energy network and elements include two sections: algebraic
equations and differential equations. Non-linear factors mainly exist in algebraic
equations, which make it difficult to solve energy system models. The convergence
and the convergence speed depend on many factors, such as the initial values of
unknown variables in the equations, the iterative flow and the method for accelerating
convergence. There are obvious differences in non-linearity sources and processing
methods of non-linearities in different energy systems.
For electrical power systems, the grid is often modelled by sparse linear equa-
tions or linear network equations, which are deduced by differentiating the models
of dynamic network components of lumped parameters. The non-linearity is mainly
embodied in the change in the power network topology, particularly in the power
electronic converter. When the topology changes frequently, the network equations
are reconstructed in the simulation. A switching action depends on the state of the
switch circuit, but the switching action time is not exactly at the end of each solution
step. Therefore, it is necessary to introduce interpolation or a compensation mecha-
nism. The other equipment models described by non-linear algebraic equations, such
as non-linear static load, are generally converted to current injections on the basis

of the bus voltages. Then, they are combined with the network equation and solved
iteratively.
The non-linear generation equations of dynamic models in the thermodynamic
system mainly include the performance of the compressor and the turbine compo-
nents, the heat transfer equation of the heat exchanger (the area multiplied by the
heat transfer temperature difference), the total volume equation of the system and
equipment, and the physical equation. In general, these equations are connected to
a non-linear equation group of high order and are solved by the Newton algorithm
and the improved algorithm.
3. Long dynamics from radical state change of working medium and multi-
physics integration
In the thermodynamic system, a change in the state of the working medium (energy
transfer medium), such as a transformation among solid, liquid and gas phases,
exhibits a non-smooth and continuous change or a significant change. For example,
when the absorption refrigeration system starts, the generating fluid is heated until
the saturation temperature is reached and natural convection heat transfer occurs.
Then, steam begins to appear. In this case, it is very challenging for only one set of
model equations to correctly describe multiple stages of the physical processes.
The overlapping of multi-time-scale physical processes of some dynamic com-
ponents in electrical power systems creates substantial difficulties in modelling and
model parameter acquisition. For example, large synchronous machines produce
long dynamics containing super transients, transient processes after a disturbance.
The electrical equation of the synchronous generator is built based on the Park trans-
formation in dq0 coordinates and is used in the system simulation, and the stator and
rotor resistance and inductance in dq0 coordinates are parameters of the equation.
Although they basically determine the electrical characteristics of the motor, these
parameters are difficult to determine by terminal tests.
Long dynamics can also be observed in energy components when radical change
occurs in the working fluid state. The overlapping fusion of multi-scale physical pro-
cesses increases the difficulty of system modelling and simulation, and it is difficult
to establish a set of models that can be adapted to the whole dynamic processes in
the equipment-system-level simulation.
1.2 Importance and Application of System Simulation
Based on the understanding of an energy internet system and the characteristics of
simulation techniques, this chapter highlights the importance of modelling, simula-
tion and analysis of complex integrated energy grids in the energy internet by first
introducing an example and then giving application scenarios for dynamic simula-
tion. The development background of simulation techniques in the energy industry
is summarized, which lays a foundation for the development of simulation models
and solution algorithms.

16 S. Zhang et al.
1.2.1 Necessity of Dynamic Simulation
The energy internet is a complex system involving a variety of forms of energy cou-
pling and containing a variety of different types of systems and devices, including fuel
gas transportation systems, heat supply systems, refrigeration systems, photovoltaic
systems, wind energy systems, biomass power generation systems and energy stor-
age systems. To improve energy production and consumption efficiency and achieve
real-time adjustment of the energy supply and consumption in the situation where
a large number of renewable energy stations are connected to the power grid, basic
research on the dynamic characteristics of the coupling and interaction among these
complex energy systems is particularly important. An energy internet simulation
based on the system combination and mathematical models can be used in the study
of the dynamic relationship among the internal equipment and energy grids of an
energy internet system, providing a theoretical basis and practical guidance for equip-
ment selection, system planning and design, operation assistance and control strategy
optimization, etc.
To date, thermoelectric simulations have been widely used in thermal power
plants. Thermoelectric simulations are vital to skill training and anti-accident
manoeuvres. The commonly used modelling software packages include the Real-
time Object-oriented Simulation Environment (ROSE), Engineering Analysis Sys-
tem V5 (EASY5), 3KEYmaster and Professional TRansient Analysis eXpert (Pro-
TRAX). Electromagnetic and electromechanical transient simulations of the power
grid have good basic research foundations and practical applications. The commonly
used simulation software packages include Bonneville Power Administration (BPA),
Power Systems Computer-Aided Design (PSCAD), Network Torsion Machine Con-
trol (NETOMAC) and Power System Analysis Software Package (PSASP). The
simulation of natural gas transmission systems also has a solid research founda-
tion and wide practical applications. These simulations are mainly used in pipeline
leakage and detection, optimization of operation, gas storage and peak-shaving. The
commonly used modelling software packages include Stoner Pipeline Simulator
(SPS), Transient Gas Network (TGNET), PIPEPHASE and Real Pipe-Gas. How-
ever, research on dynamic simulations of the energy internet started much later, and
no publicly available simulation software package has yet been reported.
To emphasize the significance of modelling, simulation and analysis of the energy
internet, a case in which the lack of doing so resulted in severe problems is presented
here.
An existing energy system of a large building was extended by integrating a
micro-gas turbine (MGT) in which the thermal energy of the exhaust gas via a heat
exchanger was used to contribute to heating the building. The nominal power output
of the MGT was 100 kW, and the turbine was controlled by prescribing a setpoint
for power output. The heat extraction in the heat exchanger was performed by water
and controlling the inlet temperature to the heat exchanger to ensure that the limit
values for the water temperature were not exceeded.

Fig. 1.5 Overheating in the combustor resulted in melting metal, deformation and further damage
The system was in operation for some weeks before it could not be restarted after
an unexpected shutdown. Taking a closer look at the MGT showed that a complete
failure had occurred (Figs. 1.5 and 1.6). The damage pictures indicate that flame
flashback might have occurred, which damaged the combustor (Fig. 1.5). Due to
overheating and embrittlement of the material, combustor parts entered the high-
speed turbine, which was damaged. Parts of the destroyed rotor penetrated the inlet
spiral to the turbine (Fig. 1.6).
A root cause analysis was performed, which included evaluating the history of
the installation, analysis of operational data and modelling and simulation.
When the unit was installed, it was necessary to place the unit in a room distant
from the room hosting the heating system of the building. Because the power and
heat output matched the needs of the building, no further in-depth analysis was
performed. The only connections between the control systems of the building were
that the required power setpoint was sent to the MGT controller and the operating
data were visualized on the control screen for the building system.
Processing the collected historical operational data resulted in graphs similar to
those shown in Figs. 1.7 and 1.8. The data were collected by the control system and
had a resolution of approximately 1/30 s. The power output that follows the setpoint,
the relative rotational speed

rpm
rpm100%

and the water temperature in the waste
heat recovery heat exchanger are visualized.

18 S. Zhang et al.
Fig. 1.6 Damage at the inlet to the turbine (inlet spiral)
Fig. 1.7 Measurements demonstrating the impact of sensor location on the control and operational
stability of a micro-gas turbine CHP system

Fig. 1.8 Zoomed-in view of Fig. 1.7 for data collected on 29.01.2011
It is interesting to observe the fluctuations in the water temperature, which are,
after exceeding a certain amplitude, followed by changes in power output and rota-
tional speed. In some cases, the rotational speed decreased well below 50%, and the
engine shut down, followed by an automatic restart. The failure of the engine was
evaluated to be caused by flashback of the flame during the large fluctuations in the
rotational speed, which was possible because the combustor was of a lean premixed
type, and reduced airflow might have resulted in flame speeds higher than the flow
velocity. Such conditions allowed the flame to propagate back into the premixing
zone. The flashback led to overheating and melting material, material embrittlement
and material breaking and entering the turbine, which caused complete failure. How-
ever, the question remained about the cause of the fluctuations because the MGT was
considered robust and stable in several other applications.
The answer was found when analysing the integrated installation, considering the
locations of sensors and valves as well as the control setup. It was found that the
temperature sensor for the water was located more than 20 metres from a control
valve for regulating the fluid temperature towards the heat exchanger by mixing
cold and hot streams to maintain a target temperature. This distance was the result
of restrictions in the area, as the integration of the MGT was not foreseen when
the building was planned. When the control system detected a need to adjust the
heat extraction, a corrective signal was sent to the control valve to adjust the inlet
temperature of the heat exchanger. The adjusted temperature was checked via the
aforementioned sensor. Due to the given tube dimensions (distance and diameter),
water with the adjusted temperature took a while to reach the sensor. This time

20 S. Zhang et al.
delay resulted in further adjustments of the valve because the control system did
not register a changed water temperature shortly after sending corrective signals
to the valve. When the sensor was finally exposed to the adjusted temperature, the
control system registered an over-corrected value exceeding the threshold within the
control system, which led to immediate counter corrections, which again suffered
from the same problem of time delay. It can easily be seen that the system ended up
operating with oscillating temperatures. When the amplitude exceeded a certain level,
the power output was adjusted, ignoring its required setpoint. Power adjustments
were predominantly performed by adjusting the rotational speed while the hot gas
temperature was targeted to be kept constant for MGT efficiency.
The variations combined with exceeding the inbuilt threshold values to protect
the MGT forced the control system in some instances to shut down and restart the
engine, which resulted in relative speed values decreasing to well below 50%.
In addition, some system internal control and safety algorithms were in conflict
because of the setup of the system. The main setpoint of the engine was the electrical
power output, which was maintained via the rotational speed (i.e. mass flow in the
GT) and the temperature in the turbine, while the water temperature/heat extraction
was controlled separately. Additionally, the restrictions in place to protect the sys-
tem from failures, which were related to, for example, the exit temperature of the
turbine, created issues. These sometimes-conflicting requirements then triggered the
shutdown of the engine followed by a fast restart.
The main reason that the failure occurred was the integration of the MGT without
considering dynamic processes and the inbuilt control system. If these considerations
had been accounted for in an early stage, corrective actions could have been taken.
For example, corrective actions could have included either changing the position of
the sensor relative to the valve or considering the distance within the control system.
1.2.2 Application Scenarios
Dynamic simulation techniques can also be applied in the field of the energy internet,
just as they can be applied in electrical power systems to achieve scheme verification,
accident analysis, countermeasure making, skill and operation training and so on.
Several application scenarios are as follows:
• Basic theory research and validation
Dynamic simulation can be used to support basic theory research and validation.
Under complicated external conditions, dynamic simulations are performed to study
unstable forms and key factors, control features, energy quality, voltage fluctuations
in system nodes after a certain disturbance/fault, analysis of harmonic content in the
system, analysis of the mechanism of commutation failure, pressure in the pipeline
network after a certain disturbance/fault, variation in flow velocity, temperature in
the heat transfer process and so on. Basic theory research can lay a foundation for

the development of energy internet techniques and the planning and construction of
practical projects.
• Verification of the planning and design scheme
According to planning and design drawings and the imported parameters of the equip-
ment and system, the system model can be established. Based on this information, a
dynamic simulation platform can provide comprehensive data analysis for verifica-
tion of the feasibility of the planning scheme, rationality of equipment capacity and
location allocation.
• Research and optimization of control strategy
Based on the dynamic simulation platform, we can effectively use the portability,
reusability, security and efficiency of the simulation model to verify the effectiveness
of the control strategy designed in an actual case of the energy internet.
• Adjustment to the configuration and operation mode
For an established industrial park energy internet, we can study the energy trans-
mission of energy attributes in the system based on the simulation platform. By
combining existing control strategies or developing new control strategies in the
platform, we can obtain the best matching of various attributes of energy strive for
the optimization of the energy efficiency, environment and system economy of the
whole park.
• Other application scenarios
Hardware-in-the-loop, online system security assessment, training of operation and
maintenance staff, fault reappearance and countermeasure formulation.
1.2.3 Foundation of an Energy Internet Dynamic Simulation
Thissectionbrieflyreviewsthebasisofthedevelopmentofenergyinternetsimulation
techniques, namely, the development status of system simulation techniques in power
grid, MG and CCHP systems.
1.2.3.1 Power System and MG Simulation
• Power System Simulation
Currently, power system simulation techniques have become relatively mature.
Many simulation approaches have been formed, such as electromagnetic transient
simulation, electromechanical transient and quasi-steady-state simulation, middle

22 S. Zhang et al.
and long-term dynamic simulation, steady-state simulation and electromagnetic-
electromechanical simulation interface techniques, to meet various demands and
conditions.
Electromagnetic transient simulation (EMTP) can accurately simulate the
dynamic response of each element and simulate HVDC (high voltage direct current)
and FACTS power electronic devices. Compared with electromechanical transient
analysis, it is necessary to apply a more precise method to analyse the electromag-
netic transient phenomenon of the power system. For example, the system must
consist of inductance, resistance and capacitance, which are described by differen-
tial equations with transient variables. The range of the frequency analysed is wide,
from low-frequency behaviour of dynamic overvoltage and dynamic control to high-
frequency behaviour of the first wave of thundershock, which covers almost all phys-
ical phenomena that affect the system. The elements of the system can be classified
as elements with lumped parameters and distributed parameters. A wave propagation
process must be considered with distributed parameters. During the electromagnetic
transient calculation, a transmission line with distributed parameters is often sim-
ulated using a cascaded Pi-type equivalent circuit with lumped parameters. If the
process of wave propagation is considered, the transmission line can be described by
the network method, the characteristic line method (also called the Bergeron model
and the Dommel model) and the improved Fourier transform method. The network
topology of a DC system changes frequently when the detailed controller model and
the action process of power electronic switches are considered.
Electromechanical transient simulation mainly analyses the transient stability dur-
ing large disturbances and steady-state stability during small disturbances in the
power system. The differential equations and algebraic equations of the whole sys-
tem according to the topological structure are obtained. Then, using the initial value,
which is the power flow without disturbances, the time variations of state variables
after a disturbance are calculated. Only the positive sequence phasor with fundamen-
tal frequency is considered to describe the whole AC system and system response,
while the circuits are described by impedances.
Hybrid simulation of electromechanical and electromagnetic transient methods
separates the network into two parts to be solved: one is an electromagnetic tran-
sient computing network, and the other is an electromechanical transient computing
network. Then, the system realizes the integrated simulation by exchanging data
through the interface. The hybrid simulation expands the scale of the electromag-
netic transient simulation and simultaneously provides the necessary background for
the simulation analysis of the electromagnetic transient network.
Based on power grid simulations, simulations of MGs have been developed
through modelling and introduced to some applications [21, 22]. An MG simulation
provides a basic model and algorithm for simulating the energy internet system.
• Distributed Resource (DR) and MG Simulation

Some achievements have been made in the study of the influence of DR and MG
penetration on a distribution network and its models. A simulation platform and sim-
ulation software package are effective methods for simulating the system operation,
which provides important support for the implementation of DR and MG projects.
The simulation of an MG includes steady-state analysis, transient stability analysis
and fine simulation of dynamic behaviours of equipment [22].
Steady-state analysis includes two parts: solving the steady-state operating point
of the system according to the given operating mode of the DR system; obtaining
the fault current by short-circuit fault analysis, which provides the basis for selecting
equipment and switching capacity.
Transient stability simulation focuses on the relatively slow dynamic processes
of the system, with simplified network components, power electronic devices, dis-
tributed power supply and various controller models, to model and simulate the
system (using a quasi-steady-state model to describe the system).
Fine simulation of device behaviours pays more attention to the faster and more
precise features of the MG or equipment. It uses electromagnetic transient simulation
as the core and considers the MG power quality, system controller design, protec-
tion and emergency control system design, short-term load tracking characteristics,
transient short-circuit current and fault ride-through capability of DRs.
In [23], electromechanical and electromagnetic transient simulations of the same
MG were carried out by using DigSilent and Matrix Laboratory (MATLAB) Sim-
PowerSystems, and the similarities and differences of the multi-dynamic-process
simulations were compared. Yan [24] used the fundamental positive sequence com-
ponent method and load identification techniques to build a MG load modelling
system by MATLAB. Lin [25] proposed the difficult point and key techniques for
solving a real-time simulation of an MG.
With the continuous penetration of DRs and changes in energy structure, smart
grids have gradually become a new generation of power grids. Power grid simulation,
combined with computer, information and communication techniques, has developed
and greatly improved in accuracy, rapidity and flexibility, laying a foundation for the
simulation of energy internet systems [25–27].
Simulation methods expanded from those of conventional grids are not enough
to calculate the new generation of power grids with MGs. Due to the complexity of
new patterns in the power grid, new standards are required to determine the stable
domain. Furthermore, it is difficult to apply electromagnetic transient simulation to
an actual MG system, which contains a large number of converters and electrical
nodes. Electromechanical transient simulation ignores the electromagnetic transient
processes of the equipment and power grid, especially converters with fast response
characteristics and distributed generation equipment.
1.2.3.2 Non-electrical Power System Simulation
A thermodynamic system is a typical non-electrical power system and is a significant
part of the planning and construction of an energy internet system. Thermodynamic

24 S. Zhang et al.
system equipment is diverse, and its dynamic response crosses over a wide time
scale. The model is described through a set of algebraic equations, ordinary differ-
ential equations and partial differential equations with distributed parameters. These
equations with their solving algorithms can cover the key technologies of energy
system modelling and simulation, which are representative.
Modelling and simulation of thermodynamic systems can be broadly divided into
2 levels: simulation analysis for devices and for the whole system.
• Simulation Analysis for Devices
Simulation analysis for devices includes optimization of the internal structure of
equipment, design and verification of all parts of equipment, performance analysis,
operation simulation with varying conditions or disturbances, control design and
analysis of control characteristics and control design. It does not need to consider
the correlation and coupling between devices. According to the main components
involved in a thermodynamic process, models with different levels of detail are estab-
lished based on various requirements. According to the results of model computation,
the dynamic behaviours of equipment components at different levels are analysed.
Then, the modelling and simulation can be divided into static lumped parameters,
static distributed parameters, dynamic lumped parameters and dynamic distributed
parameters. A lumped parameter model given by K.E. Herold in [28] is represen-
tative and can be used for calculation of the thermodynamic system and simplified
calculations. A static distributed parameter model can calculate the distributions
of refrigerant and solution in each component. Considering the differences in the
heat capacity and working fluid state of the system, [29–31] set up a more detailed
model of the generator, absorption chiller and absorption exchanger and described
the operating characteristics of the system, which greatly improved the accuracy.
At present, considerable work has been performed in research on non-electrical
power devices. In gas turbine simulation research, some notable achievements have
been made. Weng [31] with Shanghai Jiao Tong University performed a detailed
analysis on the components and overall performance of a gas turbine, especially
under variable working conditions. The paper expounded on a simplified method of
gas turbine modelling and considered that the model should be simplified according
to the physical process rather than the convenience of solving the mathematical
equation. The basic dynamic and static characteristics of gas turbines should be
preserved as much as possible. Badyda [32] reviewed the gas turbine techniques and
development trends of other advanced power technologies.
Modelling of absorption chillers is relatively mature. Zinet [33], based on the Nus-
selt falling film theory, established and resolved an absorption process model of an
absorber and generator. A three-dimensional model of a condenser was established,
and other heat transfer models were established by the simplified effectiveness-
number of transfer units (NTU) method. Then, the dynamic characteristics during
the start-up/shut down and the variable working conditions were studied. Wang [34]
modelled a direct-fired lithium bromide absorption chiller unit. A neural network
structure with high precision and generalization performance was obtained by a feed

Another Random Document on
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It is humiliating to sit in a leaky boat—it is like a lame horse or a
crooked gun; of all the needful qualities of a boat the first is to keep
out the water. So I stopped at the first village, and got a man to mix
white lead and other things, and we carefully worked this into all the
seams, leaving it to harden while I had my breakfast in the little
auberge close by the shore, where they are making the long rafts to
go down to Paris, and where hot farmers come to sip their two-
penny bottle of wine.
The raft man was wonderfully proud of his performance with the
canoe, and he called out to each of his friends as they walked past,
to give them its long history in short words. When I paid him at last,
he said he hoped I would never forget that the canoe had been
thoroughly mended in the middle of France, at the village of ——,
but I really do not remember the name.
However, there were not wanting tests of his workmanship, for the
Rob Roy had to be pulled over many dykes and barriers on the
Marne. Some of these were of a peculiar construction, and were
evidently novel in design.
A barrage reached across the stream, and there were three steps
or falls on it, with a plateau between each. The water ran over these
steps, and was sometimes only a few inches in depth on the crest of
each fall, where it had to descend some eight or ten inches at most.
This, of course, would have been easy enough for the canoe to pass,
but then a line of iron posts was ranged along each plateau, and
chains were tied from the top of one post to the bottom of another,
diagonally, and it will be understood that this was a very puzzling
arrangement to steer through in a fast current.
In cases of this sort I usually got ashore to reconnoitre, and having
calculated the angle at which we must enter the passage obliquely
(down a fall, and across its stream), I managed to get successfully
through several of these strange barriers. We came at length to one
which, on examination, I had to acknowledge was impassable, for

the chains were slack, and there was only an inch or two of law on
either side of the difficult course through them.
The Chain Barrier.
However, a man happened to see my movements and the canoe,
and soon he called some dozen of his fellow navvies from their work
to look at the navigator.
The captain was therefore incited by these spectators to try the
passage, and I mentally resolved at any rate to be cool and placid,
however much discomfiture was to be endured. The boat was
steered to the very best of my power, but the bow of the canoe
swerved an inch in the swift oblique descent, and instantly it got
locked in the chains, while I quietly got out (whistling an air in slow
time), and then, in the water with all my clothes on, I steadily lifted
the boat through the iron network and got into her, dripping wet, but
trying to behave as if it were only the usual thing. The navvies
cheered a long and loud bravo! but I felt somewhat ashamed of
having yielded to the desire for ignorant applause, and when finally

round the next corner I got out and changed my wet things, a wiser
and a sadder man, but dry.
This part of the river is in the heart of the champagne country, and
all the softly swelling hills about are thickly covered by vineyards.
The vine for champagne is exceedingly small, and grows round one
stick, and the hillside looks just like a carding-brush, from the
millions of these little sharp-pointed rods upright in the ground and
close together, without any fence whatever between the
innumerable lots. The grape for champagne is always red, and never
white, so they said, though white grapes are grown for eating.
During the last two months few people have consumed more grapes
in this manner than the chief mate of the Rob Roy canoe.
On one of these hills we noticed the house of Madame Clicquot,
whose name has graced many a cork of champagne bottles and of
bottles not champagne.
The vineyards of Ai, near Epernay, are the most celebrated for their
wine. After the bottles are filled, they are placed neck downwards,
and the sediment collects near the cork. Each bottle is then
uncorked in this position, and the confined gas forces out a little of
the wine with the sediment, while a skilful man dexterously replaces
the cork when this sediment has been expelled. One would think
that only a very skilful man can perform such a feat. When the
bottles are stored in caves, or vast cellars, the least change of
temperature causes them to burst by hundreds. Sometimes one-
fourth of the bottles explode in this manner, and it is said that the
renowned Madame Clicquot lost 400,000 in the hot autumn of 1843,
before sufficient ice could be fetched from Paris to cool her spacious
cellars. Every year about fifty million bottles of genuine champagne
are made in France, and no one can say how many more millions of
bottles of French champagne are imbibed every year by a
confiding world.
The Marne is a large and deep river, and its waters are kept up by
barriers every few miles. It is rather troublesome to pass these by

taking the boat out and letting it down on the other side, and in
crossing one of them I gave a serious blow to the stern of the canoe
against an iron bar. This blow started four planks from the sternpost,
and revealed to me also that the whole frame had suffered from the
journey at night on an open truck. However, as my own ship's
carpenter was on board, and had nails and screws, we soon
managed to make all tight again, and by moonlight came to
Dormans, where I got two men to carry the boat as usual to an
hotel, and had the invariable run of visitors from that time until
everybody went to bed.
It is curious to remark the different names by which the canoe has
been called, and among these the following:—Batteau, schiff,
bôt, barca, canôt, caique (the soldiers who have been in the
Crimea call it thus), chaloupe navire, schipp (Low German),
yacht (jacht—Danish, jaht, from jagen, to ride quickly—
properly a boat drawn by horses). Several people have spoken of it
as batteau à vapeur, for in the centre of France they have never
seen a steamboat, but the usual name with the common people is
petit batteau and among the educated people nacelle or
perissoir; this last as we call a dangerous boat a coffin or
sudden death.
An early start next morning found me slipping along with a tolerable
current and under sail before a fine fresh breeze, but with the same
unalterable blue sky. I had several interesting conversations with
farmers and others riding to market along the road which here skirts
the river. What most surprises the Frenchman is that a traveller can
possibly be happy alone! Not one hour have I had of ennui, and,
however selfish it may seem, it is true that for this sort of journey I
prefer to travel entirely seul.
Pleasant trees and pretty gardens are here on every side in plenty,
but where are the houses of the gentlemen of France, and where
are the French gentlemen themselves? This is a difference between
France and England which cannot fail to knock the observant
traveller (as Artemus Ward would say)—the notable absence of

country seats during hours and hours of passage along the best
routes; whereas in England the prospect from almost every hill of
woodland would have a great house at the end of its vista, and the
environs of every town would stretch into outworks of villas smiling
in the sun. The French have ways and fashions which are not ours,
but their nation is large enough to entitle them to a standard of their
own, just as the Americans, with so great a people agreed on the
matter, may surely claim liberty to speak with a twang, and to write
of a plow.
I am convinced that it is a mistake to say we Britons are a silent
people compared with the French or Americans. At some hundred
sittings of the table d'hôte in both these countries I have found more
of dull, dead silence than in England at our inns. An Englishman
accustomed only to the pleasant chat of a domestic dinner feels ill at
ease when dining with strangers, and so he notices their silence all
the more; but the French table d'hôte (not in the big barrack hotels,
for English tourists, we have before remarked upon) has as little
general conversation, and an American one has far less than in
England.
Here in France come six or seven middle-class men to dine. They put
the napkin kept for each from yesterday, and recognized by the
knots they tied on it, up to their chins like the pinafore of a baby,
and wipe plate, fork, and spoons with the other end, and eat bits
and scraps of many dishes, and scrape their plates almost clean, and
then depart, and not one word has been uttered.
Then, again, there is the vaunted French climate. Bright sun, no
doubt, but forget not that it is so very bright as to compel all rooms
to be darkened from ten to four each day. At noon the town is like a
cemetery; no one thinks of walking, riding, or looking out of his
window in the heat. From seven to nine in the morning, and from an
hour before sunset to any time you please at night, the open air is
delicious. But I venture to say that in a week of common summer
weather we see more of the sun in England than in France, for we
seldom have so much of it at once as to compel us to close our eyes

against its fierce rays. In fact, the sensation of life in the South, after
eleven o'clock in the morning, is that of waiting for the cool hours,
and so day after day is a continual reaching forward to something
about to come; whereas, an English day of sunshine is an enjoyable
present from beginning to end. Once more, let it be remembered
that twilight lasts only for half an hour in the sunny South; that
delicious season of musing and long shadows is a characteristic of
the northern latitudes which very few Southerners have ever
experienced at all.
The run down the Marne for about 200 miles was a pleasant part of
the voyage, but seldom so exciting in adventure as the paddling on
unknown waters. Long days of work could therefore be now well
endured, for constant exercise had trained the body, and a sort of
instinct was enough, when thus educated by experience, to direct
the mind. Therefore the Rob Roy's paddle was in my hands for ten
hours at a time without weariness, and sometimes even for twelve
hours at a stretch.
After a comfortable night at Chateau Thierry in the Elephant Hotel,
which is close to the water, I took my canoe down from the hayloft
to which it had been hoisted, and once more launched her on the
river. The current gradually increased, and the vineyards gave place
to forest trees. See, there are the rafts, some of casks, lashed
together with osiers, some of planks, others of hewn logs, and
others of great rough trees. There is a straw hut on them for the
captain's cabin, and the crew will have a stiff fortnight's work to
drag, push, and steer this congeries of wood on its way to the Seine.
The labour spent merely in adjusting and securing the parts is
enormous, but labour of that kind costs little here.
Further on there is a large flock of sheep conducted to the river to
drink, in the orthodox pastoral manner of picture-books. But (let us
confess it) they were also driven by the sagacious shepherd's dogs,
who seem to know perfectly that the woolly multitude has come
precisely to drink, and, therefore, the dogs cleverly press forward

each particular sheep, until it has got a place by the cool brink of the
water.
In the next quiet bay a village maid drives her cow to the river, and
chats across the water with another, also leading in a cow to wade
knee deep, and to dip its broad nose, and lift it gently again from
the cool stream. On the road alongside is a funny little waggon, and
a whole family are within. This concern is actually drawn along by a
goat. Its little kid skips about, for the time of toil has not yet come
to the youngling, and it may gambol now.
But here is the bridge of Nogent, so I leave my boat in charge of an
old man, and give positive pleasure to the cook at the auberge by
ordering a breakfast. Saints' portraits adorn the walls, and a
sampler worked by some little girl, with only twenty-five letters in
the alphabet, for the w is as yet ignored in classic grammars,
though it has now to be constantly used in the common books and
newspapers. Why, they even adopt our sporting terms, and you see
in a paper that such a race was only un Walkover, and that another
was likely to be un dead heat.
Suddenly in my quiet paddling here the sky was shaded, and on
looking up amazed I found a cloud; at last, after six weeks of
brilliant blue and scorching glare, one fold of the fleecy curtain has
been drawn over the sun.
The immediate effect of this cooler sky was very invigorating,
though, after weeks of hot glare (reflected upwards again into the
face from the water), it seemed the most natural thing to be always
in a blaze of light, for much of the inconvenience of it was avoided
by a plan which will be found explained in the Appendix, with some
other hints to Boating Men.
The day went pleasantly now, and with only the events of ordinary
times, which need not be recounted. The stream was steady, the
banks were peopled, and many a blue-bloused countryman stopped
to look at the canoe as she glided past, with the captain's socks and

canvas shoes on the deck behind him, for this was his drying-place
for wet clothes.
Now and then a pleasure-boat was seen, and there were several
canoes at some of the towns, but all of them flat-bottomed and
open, and desperately unsafe—well named perissoirs. Some of
these were made of metal. The use of this is well-known to be a
great mistake for any boat under ten tons; in all such cases it is
much heavier than wood of the same strength, considering the
strains which a boat must expect to undergo.
La Ferté sous Jouarre is the long name of the next stopping-place.
There are several towns called by the name La Ferté (La Fortifié),
which in some measure corresponds with the termination caster or
cester of English names. Millstones are the great specialty of this
La Ferté. A good millstone costs 50l., and there is a large exportation
of them. The material has the very convenient property of not
requiring to be chipped into holes, as these exist in this stone
naturally.
At La Ferté I put the boat into a hayloft; how often it has occupied
this elevated lodgings amongst its various adventures; and at dinner
with me there is an intelligent and hungry bourgeois from Paris, with
his vulgar and hearty wife, and opposite to them the gossip of the
town, who kept rattling on the stupid, endless fiddle-faddle of
everybody's doings, sayings, failings, and earnings. Some
amusement, however, resulted from the collision of two gossips at
our table of four guests, for while the one always harped upon
family tales of La Ferté, its local statistics, and the minute sayings of
its people, the other kept struggling to turn our thoughts to shoes
and slippers, for he was a commercial traveller with a cartful of
boots to sell. But, after all, how much of our conversation in better
life is only of the same kind, though about larger, or at any rate
different things; what might sound trifles to our British Cabinet
would be the loftiest politics of Honolulu.

When we started at eight o'clock next day I felt an unaccountable
languor; my arms were tired, and my energy seemed, for the first
time, deficient. This was the result of a week's hard exercise, and of
a sudden change of wind to the south. Give me our English climate
for real hard work to prosper in.
One generally associates the north wind with cool and bracing air,
and certainly in the Mediterranean it is the change of wind to the
south, the hated sirocce, that enervates the traveller at once. But
this north wind on the Marne came over a vast plain of arid land
heated by two months of scorching sun, whereas the breezes of last
week, though from the east, had been tempered in passing over the
mountains of the Vosges.
Forty-two miles lay before me to be accomplished before arriving to-
night at my resting-place for Sunday, and it was not a pleasant
prospect to contemplate with stiff muscles in the shoulders.
However, after twelve miles I found that about twenty miles in
turnings of the river could be cut off by putting the boat on a cart,
and thus a league of walking and 3s. 4d. of payment solved the
difficulty. The old man with his cart was interesting to talk to, and
we spoke about those deep subjects which are of common interest
to all.
At a turn in the road we came upon a cart overturned and with a
little crowd round it, while the earth was covered with a great pool
of what seemed to be blood, but was only wine. The cart had struck
a tree, and the wine-cask on it instantly burst, which so frightened
the horse that he overset the cart.
The Rob Roy was soon in the water again, and the scenery had now
become much more enjoyable.
I found an old soldier at a ferry who fetched me a bottle of wine,
and then he and his wife sat in their leaky, flat, green-painted boat,
and became very great friends with the Englishman. He had been at
the taking of Constantine in Algeria, a place which really does look

quite impossible to be taken by storm. But the appearance of a
fortress is deceptive except to the learned in such matters. Who
would think that Comorn, in Hungary, is stronger than Constantine?
When you get near Comorn there is nothing to see, and it is
precisely because of this that it was able to resist so long.
The breeze soon freshened till I hoisted my sails and was fairly
wafted on to Meaux, so that, after all, the day, begun with
forebodings, became as easy and as pleasant as the rest.

CHAPTER XV.
Meaux on the Marne—Hammering—Popish forms—Wise dogs—Blocked in
a tunnel—A dry voyage—Arbour and garret—Odd fellows—Dream on
the Seine—Almost over—No admittance—Charing-cross.
There are three hemispheres of scenery visible to the traveller who
voyages thus in a boat on the rivers. First, the great arch of sky, and
land, and trees, and flowers down to the water's brink; then the
whole of this reflected beautifully in the surface of the river; and
then the wondrous depths in the water itself, with its animal life, its
rocks and glades below, and its flowers and mosses. Now rises the
moon so clear, and with the sky around it so black that no man in
the moon can be seen.
At the hotel we find a whole party of guests for the marriage-dinner
of a newly-wedded pair. The younger portion of the company
adjourn to the garden and let off squibs and crackers, so it seems to
be a good time to exhibit some of my signal lights from my
bedroom-window, and there is much cheering as the Englishman
illumines the whole neighbourhood. Next day the same people all
assembled for the marriage breakfast, and sherry, madeira, and
champagne flowed from the well-squeezed purse of the bride's
happy father.
I have noticed that the last sound to give way to the stillness of the
night in a village is that of the blacksmith's hammer, which is much
more heard abroad than at home. Perhaps this is because much of
their execrable French ironwork is made in each town; whereas in
England it is manufactured by machinery in great quantities and at
special places. At any rate, after travelling on the Continent long
enough to become calm and observant, seeing, hearing, and, we
may add, scenting all around, the picture in the mind is full of blue

dresses, white stones, jingling of bells, and the cling, cling of the
never idle blacksmith.
This town of Meaux has a bridge with houses on it, and great mill-
wheels filling up the arches as they used to do in old London-bridge.
Pleasant gardens front the river, and cafés glitter there at night.
These are not luxuries but positive necessaries of life for the
Frenchman, and it is their absence abroad which—we believe—is
one chief cause of his being so bad a colonist, for the Frenchman
has only the expression with me for home, and no word for
wife but woman.
The cathedral of Meaux is grand and old, and see how they
masquerade the service in it! Look at the gaunt Suisse, with his
cocked-hat kept on in church, with his sword and spear. The twenty
priests and twelve red-surpliced boys intone to about as many
hearers. A monk escorted through the church makes believe to
sprinkle holy water on all sides from that dirty plasterer's brush, and
then two boys carry on their shoulders a huge round loaf, the pain
benit, which, after fifty bowings, is blessed, and escorted back to be
cut up, and is then given in morsels to the congregation. These
endless ceremonies are the meshes of the net of Popery, and they
are well woven to catch many Frenchmen, who must have action,
show, the visible tangible outside, whatever may be meant by it.
This service sets one a-thinking. Some form there must be in
worship. One may suppose, indeed, that perfect spirit can adore God
without attitude, or even any sequence or change. Yet in the Bible
we hear of Seraphs veiling their bodies with their wings, and of
elders prostrate at certain times, and saints that have a litany even
in heaven. Mortals must have some form of adoration, but there is
the question, How much? and on this great point how many wise
and foolish men have written books without end, or scarcely any
effect!
The riverside was a good place for a quiet Sunday walk. Here a flock
of 300 sheep had come to drink, and nibble at the flowers hanging

over the water, and the simple-hearted shepherd stood looking on
while his dogs rushed backward and forward, yearning for some
sheep to do wrong, that their dog service might be required to
prevent or to punish naughty conduct. This Berger inquires
whether England is near Africa, and how large our legs of mutton
are, and if we have sheep-dogs, and are there any rivers in our
island on the sea. Meanwhile at the hotel the marriage party kept on
breakfasting, even until four o'clock, and non-melodious songs
were sung. The French, as a people, do not excel in vocal music,
either in tone or in harmony, but then they are precise in time.
Afloat again next morning, and quite refreshed, we prepared for a
long day's work. The stream was now clear, and the waving tresses
of dark green weeds gracefully curved under water, while islands
amid deep shady bays varied the landscape above.
I saw a canal lock open, and paddled in merely for variety, passing
soon into a tunnel, in the middle of which there was a huge boat
fixed, and nobody with it. The boat exactly filled the tunnel, and the
men had gone to their dinner, so I had first to drag their huge boat
out, and then the canoe proudly glided into daylight, having a whole
tunnel to itself.
At Lagny, where we were to breakfast, I left my boat with a nice old
gentleman, who was fishing in a nightcap and spectacles, and he
assured me he would stop there two hours. But when I scrambled
back to it through the mill (the miller's men amazed among their
wholesome dusty sacks), the disconsolate Rob Roy was found to be
all alone, the first time she had been left in a town an unprotected
female.
To escape a long serpent wind of the river, we entered another canal
and found it about a foot deep, with clear water flowing pleasantly.
This seemed to be very fortunate, and it was enjoyed most
thoroughly for a few miles, little knowing what was to come.
Presently weeds began, then clumps of great rushes, then large
bushes and trees, all growing with thick grass in the water, and at

length this got so dense that the prospect before me was precisely
like a very large hayfield, with grass four feet high, all ready to be
mowed, but which had to be mercilessly rowed through.
This on a hot day without wind, and in a long vista, unbroken by a
man or a house, or anything lively, was rather daunting, but we had
gone too far to recede with honour, and so by dint of pushing and
working I actually got the boat through some miles of this novel
obstruction (known only this summer), and brought her safe and
sound again to the river. At one place there was a bridge over this
wet marsh, and two men happened to be going over it as the canoe
came near. They soon called to some neighbours, and the row of
spectators exhibited the faculty so notable in French people and so
rarely found with us, that of being able to keep from laughing right
out at a foreigner in an awkward case. The absurd sight of a man
paddling a boat amid miles of thick rushes was indeed a severe test
of courteous gravity. However, I must say that the labour required to
penetrate this marsh was far less than one would suppose from the
appearance of the place. The sharp point of the boat entered, and
its smooth sides followed through hedges, as it were, of aquatic
plants, and, on the whole (and after all was done!), I preferred the
trouble and muscular effort required then to that of the monotonous
calm of usual canal sailing.

Canal Miseries.
Fairly in the broad river again the Rob Roy came to Neuilly, and it
was plain that my Sunday rest had enabled over thirty miles to be
accomplished without any fatigue at the end. With some hesitation
we selected an inn on the water-side. The canoe was taken up to it
and put on a table in a summer-house, while my own bed was in a
garret where one could not stand upright—the only occasion where I
have been badly housed; and pray let no one be misled by the name
of this abode—The Jolly Rowers.
Next day the river flowed fast again, and numerous islands made the
channels difficult to find. The worst of these difficulties is that you
cannot prepare for them. No map gives any just idea of your route—
the people on the river itself are profoundly ignorant of its
navigation. For instance, in starting, my landlord told me that in two
hours we should reach Paris. After ten miles an intelligent man said,
Distance from Paris? it is six hours from here; while a third
informed me a little further on, It is just three leagues and a half
from this spot.

The banks were now dotted with villas, and numerous pleasure-
boats were moored at neat little stairs. The vast number of these
boats quite astonished me, and the more so as very few of them
were ever to be seen in actual use.
The French are certainly ingenious in their boat-making, but more of
ingenuity than of practical exercise is seen on the water. On several
rivers we remarked the walking machine, in which a man can walk
on the water by fixing two small boats on his feet. A curious mode of
rowing with your face to the bows has lately been invented by a
Frenchman, and it is described in the Appendix.
We stopped to breakfast at a new canal cutting, and as there were
many gamins about, I fastened a stone to my painter and took the
boat out into the middle of the river, and so left her moored within
sight of the arbour, where I sat, and also within sight of the ardent-
eyed boys who gazed for hours with wistful looks on the tiny craft
and its fluttering flag. Their desire to handle as well as to see is only
natural for these little fellows, and, therefore, if the lads behave well,
I always make a point of showing them the whole affair quite near,
after they have had to abstain from it so long as a forbidden
pleasure.
Strange that this quick curiosity of French boys does not ripen more
of them into travellers, but it soon gets expended in trifling details of
a narrow circle, while the sober, sedate, nay, the triste, Anglian is
found scurrying over the world with a carpet-bag, and pushing his
way in foreign crowds without one word of their language, and all
the while as merry as a lark. Among the odd modes of locomotion
adopted by Englishmen, we have already mentioned that of the
gentleman travelling in Germany with a four-in-hand and two spare
horses. We met another Briton who had made a tour in a road
locomotive which he bought for 700l., and sold again at the same
price. One more John Bull, who regarded the canoe as a queer
conveyance, went himself abroad on a velocipede. None of these,
however, could cross seas, lakes, and rivers like the canoe, which
might be taken wherever a man could walk or a plank could swim.

It seemed contrary to nature that, after thus nearing pretty Paris,
one's back was now to be turned upon it for hours in order to have a
wide, vague, purposeless voyage into country parts. But the river
willed it so; for here a great curve began and led off to the left,
while the traffic of the Marne went straight through a canal to the
right,—through a canal, and therefore I would not follow it there.
The river got less and less in volume; its water was used for the
canal, and it could scarcely trickle, with its maimed strength, through
a spacious sweep of real country life. Here we often got grounded,
got entangled in long mossy weeds, got fastened in overhanging
trees, and, in fact, suffered all the evils which the smallest brook had
ever entailed, though this was a mighty river.
The bend was more and more inexplicable, as it turned more round
and round, till my face was full in the sunlight at noon, and I saw
that the course was now due south.
Rustics were there to look at me, and wondering herdsmen too, as if
the boat was in mid Germany, instead of being close to Paris.
Evidently boating men in that quarter never came here by the river,
and the Rob Roy was a rara avis floating on a stream unused.
But the circle was rounded at last, as all circles are, however large
they be; and we got back to the common route, to civilization,
fishing men and fishing women, and on the broad Marne once more.
So here I stopped a bit for a ponder.
And now we unmoor for the last time, and enter the Rob Roy for its
final trip—the last few miles of the Marne, and of more than a
thousand miles rowed and sailed since we started from England. I
will not disguise my feeling of sadness then, and I wished that Paris
was still another day distant.
For this journey in a canoe has been interesting, agreeable, and
useful, though its incidents may not be realized by reading what has
now been described. The sensation of novelty, freedom, health, and
variety all day and every day was what cannot be recited. The close

acquaintance with the people of strange lands, and the constant
observation of nature around, and the unremitting attention
necessary for progress, all combine to make a voyage of this sort
improving to the mind thus kept alert, while the body thoroughly
enjoys life when regular hard exercise in the open air dissipates the
lethargy of these warmer climes.
These were my thoughts as I came to the Seine and found a cool
bank to lie upon under the trees, with my boat gently rocking in the
ripples of the stream below, and the nearer sound of a great city
telling that Paris was at hand. Here, said I, and now is my last
hour of life savage and free. Sunny days; alone, but not solitary;
worked, but not weary—as in a dream the things, places, and men
I had seen floated before my eyes half closed. The panorama was
wide, and fair to the mind's eye; but it had a tale always the same
as it went quickly past—that vacation was over, and work must
begin.
Up, then, for this is not a life of mere enjoyment. Again into the
harness of polite society, the hat, the collar, the braces, the gloves,
the waistcoat, the latch-key—perhaps, the razor—certainly the
umbrella. How every joint and limb will rebel against these
manacles, but they must be endured!
The gradual approach to Paris by gliding down the Seine was
altogether a new sensation. By diligence, railway, or steamer, you
have nothing like it—not certainly by walking into Paris along a dusty
road.
For now we are smoothly carried on a wide and winding river, with
nothing to do but to look and to listen while the splendid panorama
majestically unfolds. Villas thicken, gardens get smaller as houses
are closer, trees get fewer as walls increase. Barges line the banks,
commerce and its movement, luxury and its adornments, spires and
cupolas grow out of the dim horizon, and then bridges seem to float
towards me, and the hum of life gets deeper and busier, while the
pretty little prattling of the river stream yields to the roar of traffic,

and to that indescribable thrill which throbs in the air around this the
capital of the Continent, the centre of the politics, the focus of the
pleasure and the splendour of the world.
In passing the island at Notre Dame I fortunately took the proper
side, but even then we found a very awkward rush of water under
the bridges. This was caused by the extreme lowness of the river,
which on this very day was three feet lower than in the memory of
man. The fall over each barrier, though wide enough, was so shallow
that I saw at the last bridge the crowd above me evidently
calculated upon my being upset; and they were nearly right too. The
absence of other boats showed me (now experienced in such
omens) that some great difficulty was at hand, but I also remarked
that by far the greater number of observers had collected over one
particular arch, where at first there seemed to be the very worst
chance for getting through. By logical deduction I argued, that must
be the best arch, after all, for they evidently expect I will try it, and,
with a horrid presentiment that my first upset was to be at my last
bridge, I boldly dashed forward—whirl, whirl the waves, and grate—
grate—my iron keel; but the Rob Roy rises to the occasion, and a
rewarding Bravo! from the Frenchmen above is answered by a
British All right from the boat below.
No town was so hard to find a place for the canoe in as the bright,
gay Paris. I went to the floating baths; they would not have me. We
paddled to the funny old ship; they shook their heads. We tried a
coal wharf; but they were only civil there. Even the worthy
washerwomen, my quondam friends, were altogether callous now
about a harbour for the canoe.
In desperation we paddled to a bath that was being repaired, but
when my boat rounded the corner it was met by a volley of abuse
from the proprietor for disturbing his fishing; he was just in the act
of expecting the final bite of a goujon.
Relenting as we apologized and told the Rob Roy's tale, he housed
her there for the night; and I shouldered my luggage and wended

my way to an hotel.
Here is Meurice's, with the homeward tide of Britons from every Alp
and cave of Europe flowing through its salons. Here are the gay
streets, too white to be looked at in the sun, and the poupeé
theatres under the trees, and the dandies driving so stiff in hired
carriages, and the dapper, little soldiers, and the gilded cafés.
Yes, it is Paris—and more brilliant than ever!
I faintly tried to hope, but—pray pardon me—I utterly failed to
believe that any person there had enjoyed his summer months with
such excessive delight as the captain, the purser, the ship's cook,
and cabin boy of the Rob Roy canoe.
Eight francs take the boat by rail to Calais. Two shillings take her
thence to Dover. The railway takes her free to Charing Cross, and
there two porters put her in the Thames again.
A flowing tide, on a sunny evening, bears her fast and cheerily
straight to Searle's, there to debark the Rob Roy's cargo safe and
sound and thankful, and to plant once more upon the shore of old
England
The flag that braved a thousand miles,
The rapid and the snag.

Energy Internet Systems and Applications Ahmed F Zobaa

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