EDS Unit 1 (Part 1).pptx
- 1. LENDI INSTITUTE OF ENGINEERING AND TECHNOLOGY Jonnada, Andhra Pradesh- 535005 UNIT –I (Part 1) General Concepts Presented by, Dr. Rohit Babu, Associate Professor Department of Electrical and Electronics Engineering
- 2. SYLLABUS Department of Electrical and Electronics Engineering Introduction to distribution systems Load modeling and characteristics Coincidence factor Contribution factor loss factor Relationship between the load factor and loss factor Classification of loads (Residential, commercial, Agricultural and Industrial) and their characteristics.
- 3. Introduction to distribution systems Department of Electrical and Electronics Engineering BASIC TERMS AND DEFINITIONS: Terms Definitions Power System Power engineering is also called power systems engineering. It is a subfield of electrical engineering that deals with the generation, transmission, distribution and utilization of electric power, and the electrical apparatus connected to such systems. Distribution System Electric power distribution is the final stage in the delivery of electric power; it carries electricity from the transmission system to individual consumers. Electric supply Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Electric power is usually produced by electric generators, but can also be supplied by sources such as electric batteries. Electrical Network An electrical network is an interconnection of electrical components (e.g. batteries, resistors, inductors, capacitors, switches) or a model of such an interconnection, consisting of electrical elements (e.g. voltage sources, current sources, resistances, inductances, capacitances).
- 4. Introduction to distribution systems Department of Electrical and Electronics Engineering Terms Definitions Connected load Total Connected Load (TCL) is the mechanical and electrical load (in kW) that will be connected (or to consumed) for that particular area Demand or Load The amount of electricity being used at any given moment by a single customer, or by a group of customers. The total demand on a given system is the sum of all of the individual demands on that system occurring at the same moment. The peak demand is the highest demand occurring within a given span of time, usually a season or a year. The peak demand that a transmission or distribution system must carry sets the minimum requirement for its capacity (see also the definition for energy). Maximum demand Maximum demand is the highest level of electrical demand monitored in a particular period usually for a month period. Electric supply Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Electric power is usually produced by electric generators, but can also be supplied by sources such as electric batteries.
- 5. Introduction to distribution systems Department of Electrical and Electronics Engineering Terms Definitions Base load A base load power plant is an electric generation plant that is expected to operate in most hours of the year. Distribution Distribution means to spread the product throughout the marketplace such that a large number of people can buy it. Load Model A load model in this matter is a mathematical representation of the relationship between power and voltage, where the power is either active or reactive and the output from the model. The voltage (magnitude and/or frequency) is the input to the model. Coincidence factor Coincidence factor is the ratio of the coincident, maximum demand or two or more loads to the sum of their non coincident maximum demand for a given period; the reciprocal of the diversity factor, and is always less than or equal to one. Contribution factor The contribution factor is the percentage of end user revenue that will be contributed to the universal service fund to support the universal service programs, as established by the FCC. The contribution factor changes every quarter.
- 6. Introduction to distribution systems Department of Electrical and Electronics Engineering Terms Definitions Load-loss factor Load-loss factor (LLF) is a factor which when multiplied by energy lost at time of peak and the number of load periods will give overall average energy lost. It is calculated as the ratio of the average load loss to the peak load loss. For electricity utilities, expect about 0.03 Residential Load The term residential use or residential load means “all usual residential, apartment, seasonal dwelling and farm electrical loads or uses, but only the first four hundred horsepower during any monthly billing period of farm irrigation and pumping for any farm.” Domestic Load The domestic load is defined as the total energy consumed by the electrical appliances in the household work. It depends on the living standard, weather and type of residence. The domestic loads mainly consist of lights, fan, refrigerator, air conditioners, mixer, grinder, heater, ovens, small pumping, motor, etc. The domestic load consume very little power and also independent from frequency. This load largely consists of lighting, cooling or heating.
- 7. Introduction to distribution systems Department of Electrical and Electronics Engineering Terms Definitions Commercial Load Commercial load mainly consist of lightning of shops, offices, advertisements, etc., Fans, Heating, Air conditioning and many other electrical appliances used in establishments such as market restaurants, etc. are considered as a commercial load. Industrial Loads Industrial load consists of small-scale industries, medium scale industries, large scale industries, heavy industries and cottage industries. The induction motor forms a high proportion of the composite load. The industrial loads are the composite load. The composite load is a function of frequency and voltage and its form a major part of the system load. Agriculture Loads This type of load is mainly motor pumps-sets load for irrigation purposes. The load factor of this load is very small e.g. 0.15 – 0.20.
- 8. Introduction to distribution systems Department of Electrical and Electronics Engineering • The electric utility industry was born in 1882 when the first electric power station, Pearl Street Electric Station in New York City, went into operation. • The electric utility industry grew very rapidly, and generation stations and transmission and distribution networks have spread across the entire country. • In general, the definition of an electric power system includes a generating, a transmission, and a distribution system. • In the past, the distribution system, on a national average, was estimated to be roughly equal in capital investment to the generation facilities, and together they represented over 80% of the total system investment Figure 1 Typical investment trends in electric utility plants in service.
- 9. Introduction to distribution systems Department of Electrical and Electronics Engineering Distribution System Planning • System planning is essential to assure that the growing demand for electricity can be satisfied by distribution system additions that are both technically adequate and reasonably economical. • The objective of distribution system planning is to assure that the growing demand for electricity, in terms of increasing growth rates and high load densities, can be satisfied in an optimum way by additional distribution systems, from the secondary conductors through the bulk power substations, which are both technically adequate and reasonably economical. • Distribution system planners must determine the load magnitude and its geographic location. • The distribution system is particularly important to an electrical utility for two reasons: (1) its close proximity to the ultimate customer and (2) its high investment cost.
- 10. Introduction to distribution systems Department of Electrical and Electronics Engineering • The demand, type, load factor, and other customer load characteristics dictate the type of distribution system required. • The distribution transformer loads are then combined to determine the demands on the primary distribution system. • The primary distribution system loads are then assigned to substations that step down from transmission voltage. • The distribution system loads, in turn, determine the size and location, or siting, of the substations as well as the routing and capacity of the associated transmission lines.
- 11. Introduction to distribution systems Department of Electrical and Electronics Engineering Factors Affecting System Planning • The number and complexity of the considerations affecting system planning appear initially to be staggering. • Demands for ever-increasing power capacity, higher distribution voltages, more automation, and greater control sophistication constitute only the beginning of a list of such factors.
- 12. Introduction to distribution systems Department of Electrical and Electronics Engineering Figure 2 Factors affecting load forecast. 1. Load Forecasting The load growth of the geographic area served by a utility company is the most important factor influencing the expansion of the distribution system. Therefore, forecasting of load increases and system reaction to these increases is essential to the planning process. There are two common time scales of importance to load forecasting: long range, with time horizons on the order of 15 or 20 years away, and short range, with time horizons of up to 5 years distant.
- 13. Introduction to distribution systems Department of Electrical and Electronics Engineering 2. Substation Expansion Figure 3 Factors affecting substation expansion. • The planner makes a decision based on tangible or intangible information. • For example, the forecasted load, load density, and load growth may require a substation expansion or a new substation construction.
- 14. Introduction to distribution systems Department of Electrical and Electronics Engineering 3. Substation Site Selection Figure 4 Factors affecting substation siting. The distance from the load centers and from the existing subtransmission lines as well as other limitations, such as availability of land, its cost, and land use regulations, is important.
- 15. Introduction to distribution systems Department of Electrical and Electronics Engineering Figure 5 Substation site selection procedure. • The service region is the area under evaluation. • It may be defined as the service territory of the utility. • An initial screening is applied by using a set of considerations, for example, safety, engineering, system planning, institutional, economics, and aesthetics. • This stage of the site selection mainly indicates the areas that are unsuitable for site development.
- 16. Introduction to distribution systems Department of Electrical and Electronics Engineering 4. Other Factors Figure 6 Factors affecting total cost of the distribution system expansion.
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