Rehabilitation of nablus electrical network by adding a new connection point

An- Najah National University
Rehabilitation of Nablus Electrical Network by adding a
new connection point
Submitted To :
Dr. Maher Khammash
Prepared By :
Ahmad HatemAbd-Albaqi
&
Ali Namrouti
2015-2016
1

Introduction
 Our project is to study the performance of Nablus
Network and to add a new connection point in the eastern
region of the city of Nablus at the village of " Huwwara
" with maximum capacity up to 20 MW.
 Analyzing and make a load flow study using ETAP
software and trying to achieve the optimum performance
for “Eastern Region” Network .
 Taking into consideration that there are 6 connection
points in the electrical network of the city of Nablus.
2

Objectives
 Collecting data for the new connection point including all parameters and
their specifications ( location, transmission lines , switchgear , load ).
 Designing the one line diagram in ETAP program for new condition by
adding the new supply bus .
 Improving the voltage level and reducing the losses and correcting of
power factor in the network .
 Making the system more protected by increasing reliability and stability .
 Analyzing the network under maximum load condition using load flow
analyses.
 To get economical benefit when improving the performance of network.
3

Why new connection point ?
 The main problem which faces Eastern Region Network is that the power
supplied by IEC ‫االسرائيلية‬ ‫القطرية‬ ‫الشركة‬) ) is not enough for the demand in the city,
especially in the summer season . And because the old connection point has a
capacity up to 20 MW which is not sufficient for the network demand because
the old connection point supplies more than one region, such as the industrial
area and “Al-Bathan” .
 To solve this problem , we add a new connection point with IEC in the eastern
region of the city of Nablus in the village of " Huwwara " through an over head
transmission line of 33 kV. The max demand is reached approximately to (20
MW) to cover the total demand .
4

Eastern Region Network
Before & After 5

Methodology
Collecting
data for
new C.P
and
elements
Plotting
one line
diagram
for new
network
Changing
the voltage
level to 11
kV instead
of 6.6 Kv
Analyzing
the
network
under max.
load case
Improve
p.f to
avoid
penalties
Making
Economical
study for
our project
6

 Plotting one-line diagram using ETAP
software for new Network
 We make a load flow study and analysis Network using ETAP
software .
 Components of the network :
1. Two sources (33 kV) .
2. ( 280 ) bus in this network .
3. ( 107 ) loads( residential, industrial, commercial).
4. Substation with ( 2 ) power transformer .
5. ( 108 ) Distribution transformers .
7

 Changing the Voltage Level from
6.6 to 11 kV
 In this case, each 6.6 kV low voltage side will be exchanged by 11 kV. The
same transformers are used because the transformers which are available
have two windings on the low voltage side of 6.6 kV and 11 kV.
 Distribution transformers of 11/0.4 and 6.6/0.4 kV will not be changed too .
So, no new transformers are needed .
 After raising the voltage to 11 kV , the voltage drop was decreased and a
slight improvement to the power factor was observed .
8

 The results of load flow in original
case
Operating Voltage(kV)Rated Voltage(kV)Bus
34.00034Bus 1
33.04333Bus 20
31.50333Bus 65
31.01633Bus 99
10.35511Bus 110
10.30211Bus 133
10.28011Bus 200
10.08711Bus 269
0.3650.4Bus 122
0.3620.4Bus 182
0.3560.4Bus 227
9

Some of under voltage buses : 10

Summary of results in original case
%PFMVAMVarMW
82.24 lag41.86423.81534.430Source (swing
bus)
--5.8762.700Apparent losses
11
 From the above results , there are many problems in the network .The P.F of the
swing bus = 82.24 Lagging , which causes high penalties and losses . So, we try to
increase the power factor of the busses and the voltage of the buses which is not
included in the acceptable range .
 Therefore ,we note that when we change the Voltage Level from 6.6 to 11 kV the
losses for network decrease from 8.9% to 7.8% .

Maximum load case
 The voltage should be within this range :
1.05 V nominal < V < 1.1 V nominal
 In first stage of the analysis of the network we have to take the
maximum load in daily load curve ,then applied it on ETAB .
 We started the study of this case after we applied the data
needed Like load factor and other data.
12

Load factor
 We have the average value of loads by using the load factor of
each load which we got from the real data of network and real
daily load curves from SCADA system
 The average demand load factor in our network is 75% that
means the average load to the maximum load ratio is 75% which
considered as a very good operating load factor .
13

Our goal is to improve the voltages within the range
by using the following steps :
 Tab changing in the transformers.
 Adding capacitors to produce reactive power.
 Changing and replacing transformer.
 Add another connection point .
The tap changer of the secondary side of the 2 power
transformers (33-11 kV) is raised to 10% , and tap change
in all distribution transformers by 5% .
14

Summary of results in maximum load
case
15
%PFMVAMVarMW
83.25 lag42.32023.44635.232Source (swing
bus)
 The losses in the network decrease . The losses before were = 2.700 MW,
but the losses after become =2.415 MW .
 For more improvement we add capacitor banks at the low voltage level and
this is a temporary solution but we need a major solution to cover the total
demand in the city. So , we choose to add a new connection point .

Add a new connection point
Comparing the voltages before and after adding the new connection point.
16
Voltage with two
connection point (kV)
Voltage with one
connection point (kV)
Bus
34.00034.000Bus 1
33.64933.043Bus 20
33.13431.503Bus 65
32.66631.016Bus 99
11.02410.355Bus 110
10.97310.302Bus 133
10.95210.280Bus 200
10.80610.087Bus 269
0.3900.365Bus 122
0.3870.362Bus 182
0.3830.356Bus 227

Some of under voltage buses : 17

Summary of results for new network 18
%PFMVAMVarMW
83.39 lag40.28822.23733.595Source (swing
bus)
 We note that when adding a new connection point the losses for
network decrease from 8.9% to 3.4% .
 The P.F of the swing bus = 83.39 lag , which is low and causes a lot of
penalties on both the company and consumers. So, we have to try to
increase the power factor of the busses .

Power Factor Improvement
 It is important to keep the P.F above 0.92 on the distribution transformer so as to
minimize the electrical losses and do not paying penalties.
 How to improve the P.F ??
19

We added shunt capacitor banks at the buses at both
transmission and distribution levels and loads with value :
( 300 , 400 , 1000 ) kVAR .
20

Summary of results after improvement the
network
%PFMVAMVarMW
92.09 lag36.51414.23333.626Source (swing
bus)
21
 After adding the capacitor banks the losses in the network decrease to 1.010 MW
 The P.F = 92.09% which it was achieved , since a P.F was lower than that , it would
lead to penalties on both the “NEDCO” and consumers .

Elements Of The Network
1- Sources :
Eastern Region are fed from 2 connection point by Israel Electrical
Company (IEC), at 33KV.
2- Transformers :
 Power Transformers :
This network consists of (2) power transformer (33/11) KV with ratings
10 MVA .
 Distribution transformers :
1. 41 distribution transformers (33/0.4)KV
2. 67 distribution transformers (11/0.4)KV
22
Number of
Transformers
Transformer
Ratings (KVA)
2 2000
1 1600
3 1000
43 630
34 400
16 250
8 160
1 100
108 Total

3- Transmission Line & cable :
 Over Head Line:
The conductors used in the network are ACSR (Aluminum Conductor
Steel Reinforced)
 Under Ground Cable :
The underground cable used in the network are XLPE Cu .
4- Switch gear :
switchgears in substations are located on both the high and low
voltage sides of large power transformers .
Selection depends on : Voltage level ,Number of lines ,Location of
substation , Possibility of expansion
23

 Switchgear contain of :
A. Circuit Breaker :
 How to choose CB :
• I C.B >= Ksafty * I max load .
• VC.B >= V system.
• I breaking capacity >= 1.2 * I S.C
 The Specifications of the Circuit Breaker that
we have used are as follows:
• Ur = 36 kV, Up = 170 kV , Ud = 70kV ; 1 min
• Ir = 1250 A , Ik = 25 kA ; tk = 1sec , Ip = 62.5 kA
24

B. Bus-Bar :
The Bus-Bar modules are either with single phase or three phase
enclosure. Three phase enclosures are compact and have lesser eddy
current losses.
C. Isolator Switch :
Isolating Switches are normally switched only when No Load .
D. Earth Switch :
Earth switch is used to discharge the voltage on the circuit to the earth for
safety , earth switch is mounted on the frame of the isolaters
25

5 - Measurement in the medium voltage :
 Current Transformers
 Potential Transformers
6 - Supervisory Control & Data Acquisition (SCADA) :
SCADA is a system for remote monitoring and control that
operates with coded signals over communication channels.
26

Economical Study
In this project it is important to study the economical calculation to find if our work is suitable
or not .
 Saving in penalties :
P.F before imp. = 0.83
P.F after imp. = 0.92
Pav = L.F * Pmax
= 0.75 * 33.626 = 25.21 MW
Total energy per year = Pav * 8760= 220839.6 MWH.
Total cost per year = Total energy * cost (NIS/KWH) = 132503760 NIS/year.
Saving in penalties of P.F = 115278.27 NIS/year.
 Saving in losses :
Saving in losses = cost of losses before – cost of losses after
= 1064340 – 398142
= 666198 NIS/year.
27
Power Factor P.F Penalties
P.F ≥ 0.92 No Penalties.
0.92 > P.F ≥ 0.8 1% of total bill for each one under 0.92
0.8 > P.F ≥ 0.7 1.25% of total bill for each one under 0.92
P.F < 0.7 1.5% of total bill for each one under 0.92

Economical Study
 Simple Pay Back Period :
Total fixed capacitor banks using = 7.3 MVAR.
Cost of fixed capacitor = 18000 NIS / MVAR .
Total cost of capacitor banks = 7.3 * 18000 = 131400 NIS.
The cost of under ground cable XLPE (1*240 mm2) = 100 NIS / 1 meter
Total cost = 100 * 8000 = 800000 NIS .
The cost of Infrastructure (such as: excavations, power source, accessories) = 100 NIS/1meter
Total cost = 100 * 8000 = 800000 NIS .
The cost of ( Links , wages of workers , equipment , Towers , installation cost and maintenance ) = 300000 NIS
The cost of ( Internal equipment, construction, measurement device , SCADA system ) = 500000 NIS .
Total capital cost = 131400 + 800000 + 800000 + 300000 + 500000 = 2531400 NIS
Total saving = saving in losses + saving in penalties
= 666198 + 115278.27 = 781476.27 NIS
S.P.B.P = Investment / Saving = 2531400 / 781476.27 = 3.23 years
28

How our new connection point will affect on
Nablus network ?
29
RehabilitationoftheNabluselectricalnetwork
Rehabilitation of the Nablus electrical network

Conclusions
 After the analysis and adding a new connection point , drop voltage was decreased ,
apparent losses was reduced too .
 When adding a new connection point the losses for network decrease
from 8.9% to 3.4% .
 The power factor was improved to over 92% which will reduce any penalties paid to
"IEC" on both "NEDCO" Company and consumers as will, and this is duo to adding a new
connection point .
 The network at full load need to 34 MW , but the availability of current two connection
point is 40 MW . So, now we in the save side .
 The time needed to recover the cost for the project is about 3 year . And the new
network will be feed the new growth of load for the period from now to 2025 ,
depending on the annual increase of the loads to cover the demand in the city.
30

Huwwara connection point 31

Askar substation 32

Switchgear in Askar substation 33

SCADA system 34

Recommendation
 Finally , we hope from NEDCO with which we have contributed in
gathering information and data about our project to take into
consideration our calculation and improvement of the electrical network
seriously . we also hope to see our project in Huwwara to be truly
applied on the ground of reality .
THANK YOU FOR YOUR ATTENTION
35

Rehabilitation of nablus electrical network by adding a new connection point

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