Optimum performances of ramallah

I thank our guide ALLAH for giving me the opportunity to study at An-Najah University and I thank my family for supporting me in every moment

whether it was bad or good.

I also admit the hard work that have been done from my supervisor and every doctor that I had the owner to study between their hands specially doctor Maher Khammash and I hope to pay bake the favor for all of you,

whether in my work or in my country or even in any other country ,thank you all.

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This report was written by student at the Electrical Engineering Department, Faculty of Engineering, An-Najah National University. It has not been altered or corrected. Other than editorial corrections, as a result of assessment and it may

contain language as well as content errors. The views expressed in it together with any outcomes and recommendations are solely those of the students. An-Najah

National University accepts no responsibility or liability for the consequences of this report being used for a purpose other than the purpose for which it was

commissioned.

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List of Contents

List of contents ………………………………………………….………….…… 1 List of figures ……………………………………………………………..…… 2 List of tables ……………………………………………………….........….... 3 Abstract …………………………………………………………..…….…… 4 The one-line diagram …………………………………………….………..….…. 5 1.1 General introduction …………………………………………..………….…..8 1.2 Description of Ramallah network ………………………………………….….9 1.3 Substation ………………………………………………………….……….…10 1.4 Elements of network ……………………………………………..……….….. 11 1.5 Load categories ……………………………………………………..…….….. 12 1.6 Introduction to power system protection …………………………..……….… 12 1.7 Constrains ……………………………………………………….……………. 16 1.8 Standard /Code …………………………………………………………….…. 16 1.9 Methodology …………………………………………………………………..17 2.1 Analysis of maximum condition …………………………….……………….. 18 2.2 Maximum improved condition ……………………………..………………… 22 2.3 Maximum condition results …………………………..…………..……….…..26 3.1 Analysis of minimum condition ………………………………….…………...28 3.2 Minimum improved condition ………………………………………..……….32 3.3 Minimum condition results ………….………….…………………...………..36 4. Power system protection calculation..……………….……………………..…..38 5. Economical study ….………………….…………………………….….……….45 Conclusion and recommendation ………………………………………………….47 Appendix …………………………………………………………………………..48

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List of Figures

Fig “1.0” : one line diagram …………………………………………………7 Fig “2.1”: Singel ,deer Jreer and biteen substation ………………………….18 Fig “2.2”: Tahounah ,Ramallah north substation ……………………………19 Fig “2.3”: Silvana ,Ramallah city and Kharbatha station ……………………19 Fig “2.4”: Al-moalmeen substation ………………………………………….20 Fig “2.5”: Nabi-Saleh substation …………………………………………….21 Fig “2.6”: Atarot main con. point ……………………………………………21 Fig “2.7”: improved Singel, deer Jreer and biteen sub. ………………………22 Fig “2.8”: imp. Tahounah, Ramallah north sub. ……………………………..23 Fig “2.9”: imp. Atarot main con. point ……………………………………….23 Fig “2.10”: imp. Silvana, Ramallah city sub. ………………………………...24 Fig “2.11”: imp. Moalmeen sub. ……………………………………………..25 Fig “2.12”: imp. Nabi-Saleh sub. …………………………………………..…25 Fig “3.1”: Singel ,deer Jreer and biteen substation ………………………….28 Fig “3.2”: Tahounah ,Ramallah north substation ……………………………29 Fig “3.3”: Silvana ,Ramallah city and Kharbatha station ……………………29 Fig “3.4”: Al-moalmeen substation ………………………………………….30 Fig “3.5”: Nabi-Saleh substation …………………………………………….30 Fig “3.6”: Atarot main con. point ……………………………………………31 Fig “3.7”: improved Singel, deer Jreer and biteen sub. ………………………32 Fig “3.8”: imp. Tahounah, Ramallah north sub. ……………………………..33 Fig “3.9”: imp. Atarot main con. point ……………………………………….33 Fig “3.10”: imp. Silvana, Ramallah city sub. ………………………………...34 Fig “3.11”: imp. Moalmeen sub. ……………………………………………..35 Fig “3.12”: imp. Nabi-Saleh sub. …………………………………………..…35 Fig “4.1”: Nabi-Saleh Tr-r. before protection …………………………………39 Fig “4.2”: Nabi-Saleh Tr-r. after protection …………………………………..41 Fig “4.3”: Moalmeen sub. before protection ………………………………….42 Fig “4.4”: Moalmeen sub. after protection ……………………………………44

List of Tables

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Table “1.1”: Rating of power transformers …………………………….…..11 Table “1.2”: Load category …………………………………………….…..12 Table “2.1”: The voltages before and after imp. the max cond. …………….26 Table “2.2”: The power factor before and after imp the max …………...…27 Table “2.3”: The total demand and losses for max cond. ……….……….…27 Table “3.1”: The voltages before and after imp. the max cond. …..…...…..36 Table “3.2”: The power factor before and after imp the max ……….…..…37 Table “3.3”: The total demand and losses for max cond. …………….……37

Abstract

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The important aspects to be covered in this project are preparing the initial data for Ramallah & Al-Bireh Governoratenetwork and subject to a load flow study using modern software like ETAP to improve the voltage level and reduce the electrical losses in the network by improving the power factor and increase the reliability of the network and deals with the protection of network.

The objectives of the project are:

To be familiar with Ramallah & Al-Bireh Governoratenetwork. To improve the voltage level and decrease the real power losses. To get an economic benefits. To increase the reliability of the network. To keep the network protected and stable by isolating only the components those are

under fault.

In order to do these objectives these method will be followed:

Built the line diagram for ETAP program. Collect the data for the network including all parameters. Load flow analysis and study for network under (max. min. and fault condition). Voltage control of the network by using T.F and reactive power sources. Increase the capability of the transformer and transmission line. Using the protective relay or circuit breaker or by using the batteries to keep the network

stable and under protection.

The idea of this project is known but its applied with different way by using modern software’s and solving some real practical problems from which this network suffer by the cooperation ‘’Jerusalem District Electricity Company –‘JDECO’ which gives us the help we need to take any decision to develop the network.

The one line diagram

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Fig 1.0

1.1 Introduction

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In power engineering, the power flow study, also known as load-flow study, is an important tool involving numerical analysis applied to a power system. A power flow study usually uses simplified notation such as a one-line diagram and per-unit system, and focuses on various forms of AC power (i.e.: voltages, voltage angles, real power and reactive power). It analyzes the power systems in normal steady-state operation. A number of software implementations of power flow studies exist.

In addition to a power flow study, sometimes called the base case, many software implementations perform other types of analysis, such as short-circuit fault analysis, stability studies (transient & steady-state), unit commitment and economic load dispatch analysis. In particular, some programs use linear programming to find the optimal power flow, the conditions which give the lowest cost per kilo watt hour delivered.

Power flow or load-flow studies are important for planning future expansion of power systems as well as in determining the best operation of existing systems. The principal information obtained from the power flow study is the magnitude and phase angle of the voltage at each bus, and the real and reactive power flowing in each line.

Commercial power systems are usually too large to allow for hand solution of the power flow. Special purpose network analyzers were built between 1929 and the early 1960s to provide laboratory models of power systems; large-scale digital computers replaced the analog methods. The Power system is complicated electrical networks used to supply, transmit, and use electrical energy. The networks that supply’s towns containing houses hospitals industrial region called the GRID. The grid contains generators that supply the power, the transmission system that carries the power from the generating centers to the load centers and the distribution system that feeds the power to nearby homes and industries. The majority of these systems rely upon three-phase AC power - the standard for large-scale power transmission and distribution across the modern world. Specialized power systems that do not always rely upon three-phase AC power are found in aircraft, electric rail systems, ocean liners and automobiles.

1.2 Description of Ramallah network

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About Al-Quds electrical company

Covering the concession area company is currently approximately 25% of the West Bank and the equivalent of 366 square kilometers distributed as follows:

Jerusalem area

47 villages and covers an area of 82 square kilometers (not including, of course, Jerusalem was occupied in 1948) Ramallah area: of the 72 villages and covers an area of 174 square kilometers.

The Bethlehem area: of the 43 villages, town and covers an area of 80 square kilometers. Jericho area: of the 7 places and covers an area of 30 square kilometers.

The central station is located in Shu'fath about 2 km from the status of Jerusalem and built in 1956 on an area of 15639 square meters, was officially inaugurated in 17/8/1959.

The sub-stations at the basic construction were:

Station Bethlehem / Pincushion Issuing the Ramallah / transmission Main offices in Jerusalem Jericho station

In 18/6/1985 the company took a land leased from the municipality of Jerusalem area 5000 m2 the value of 12500 thousand shekels annually has tried to abolish the municipal lease contract

from one party to that agreement was reached in the end to the rent increase to 15 thousand dollars a year, the company used a piece of land in question as a repository of the pillars of iron, wood and electrical cables a result of the steady expansion witnessed by the company.

1.3 Substations

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We have in Ramallah network 14 main substations that feed the city as follow

Silvana which has two transformers (33\11) KV of 15 MVA Capacity. Al Terah which has one transformer (33\11) KV of 10 MVA Capacity. Ramallah north which has two transformers (33\11) KV of 15 MVA and 10 MVA

Capacity. Biteen west which has one transformer (33\11) KV of 15 MVA Capacity. Biteen central which has one transformer (33\6.6) KV of 3 MVA Capacity. Ras Al Tahounah which has one transformer (33\11) KV of 10 MVA Capacity. Dar Al Moalmeen which has two transformers (33\11) KV of 10 MVA and 15 MVA

Capacity. Singel which has one transformer (33\11) KV of 10 MVA Capacity. Deer Jreer which has one transformer (33\11) KV of 5 MVA Capacity. Silwad which has one transformer (33\11) KV of 3 MVA Capacity. Al-Rehan which has one transformer (33\11) KV of 5 MVA Capacity. Kharbatha which has one transformer (33\11) KV of 15 MVA Capacity. Nabi-Saleh which has one transformer (33\11) KV of 15 MVA Capacity. Tri-fitness which has two transformers (33\11) KV of 10 MVA and 15 MVA Capacity.

There is transmission lines between the main buses is 33 KV, the network is ring configuration, all Ramallah loads take power from these buses

These buses feed from 7 feeders as follows:

Pereg has 20 MVA Capacity. Ofar has 20 MVA Capacity. Ramallah 20 MVA Capacity. Rama1 20 MVA Capacitiy. Al Ram 20 MVA Capacity. Nabi-Saleh 10 MVA Capacity. Qalandia 20 MVA Capacity.

These feeders come from the main connections point with the Israelis electric company.

1.4 Elements of the network

I. Transformers

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The high voltage transformers on the main substations (33KV/11KV)

MVA # of transformers Total capacity(MVA)15 8 12010 6 605 1 5

3(33KV/6.6KV) 2 6Total 18 191

TABLE -1.1- (Ratings of power transformers)

All transformers has tap changer with load= ±10%

II. Transmission lines

33KV transmission

Overhead transmission lines ACSR (3X120+1X50) mm

Underground CABLE COPPER XLPE single core 150mm

11KV transmission

Overhead transmission lines ACSR (3X50+1X50) mm

Underground CABLE COPPER XLPE (3X95 +1X50) mm

1.5 Load categories

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The nature of the loads in Ramallah city varies between residential, commercial, industry, water pumps and light streets, and the following table shows each category and it’s percentage from the total consumption.

Table1.2 Load category and its percentage consumption from total consumption

1.6 Power-system protection

is a branch of electrical power engineering that deals with the protection of electrical power systems from faults through the isolation of faulted parts from the rest of the electrical network. The objective of a protection scheme is to keep the power system stable by isolating only the components that are under fault, whilst leaving as much of the network as possible still in operation. Thus, protection schemes must apply a very pragmatic and pessimistic approach to clearing system faults. For this reason, the technology and philosophies utilized in protection schemes can often be old and well-established because they must be very reliable.

Components

Protection systems usually comprise five components:

Current and voltage transformers to step down the high voltages and currents of the electrical power system to convenient levels for the relays to deal with;

Protective relays to sense the fault and initiate a trip, or disconnection, order; Circuit breakers to open/close the system based on relay commands; Batteries to provide power in case of power disconnection in the system. Alarm signals and control wires.

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Type of sector Percentage Residential sector (60 – 65)%Industrial sector (15 – 18) %Commercial sector (10 – 12)%Water pumping 5%Street lighting (3 – 4)%

For parts of a distribution system, fuses are capable of both sensing and disconnecting faults.

Failures may occur in each part, such as insulation failure, fallen or broken transmission lines, incorrect operation of circuit breakers, short circuits and open circuits. Protection devices are installed with the aims of protection of assets, and ensure continued supply of energy.

Switchgear is a combination of electrical disconnects switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switches are safe to open under normal load current, while protective devices are safe to open under fault current.

Protective device

A protective relay for distribution networks

Protective relays control the tripping of the circuit breakers surrounding the faulted part of the network

Automatic operation, such as auto-reclosing or system restart Monitoring equipment which collects data on the system for post event analysis

While the operating quality of these devices, and especially of protective relays, is always critical, different strategies are considered for protecting the different parts of the system. Very important equipment may have completely redundant and independent protective systems, while a minor branch distribution line may have very simple low-cost protection.

There are three parts of protective devices:

Instrument transformer: current or potential (CT or VT) Relay Circuit breaker

Advantages of protected devices with these three basic components include safety, economy, and accuracy.

Safety: Instrument transformers create electrical isolation from the power system, and thus establishing a safer environment for personnel working with the relays.

Economy: Relays are able to be simpler, smaller, and cheaper given lower-level relay inputs.

Accuracy: Power system voltages and currents are accurately reproduced by instrument transformers over large operating ranges.

Classification of the relay

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* Principle of operation

* Nature of the relay

* Tome of operation

* Kind of contacts

Types of protection

Generator sets – In a power plant, the protective relays are intended to prevent damage to alternators or to the transformers in case of abnormal conditions of operation, due to internal failures, as well as insulating failures or regulation malfunctions. Such failures are unusual, so the protective relays have to operate very rarely. If a protective relay fails to detect a fault, the resulting damage to the alternator or to the transformer:

Damage to the alternator or to the transformer might require costly equipment repairs or replacement, as well as income loss from the inability to produce and sell energy.

High-voltage transmission network – Protection on the transmission and distribution serves two functions: Protection of plant and protection of the public (including employees). At a basic level, protection looks to disconnect equipment which experience an overload or a short to earth. Some items in substations such as transformers might require additional protection based on temperature or gas pressure, among others.

Overload and back-up for distance (overcurrent) – Overload protection requires a current transformer which simply measures the current in a circuit. There are two types of overload protection: instantaneous overcurrent and time overcurrent (TOC). Instantaneous overcurrent requires that the current exceeds a predetermined level for the circuit breaker to operate. TOC protection operates based on a current vs time curve. Based on this curve if the measured current exceeds a given level for the preset amount of time, the circuit breaker or fuse will operate.

Earth fault ("ground fault" in the United States) – Earth fault protection again requires current transformers and senses an imbalance in a three-phase circuit. Normally the three phase currents are in balance, i.e. roughly equal in magnitude. If one or two phases become connected to earth via a low impedance path, their magnitudes will increase dramatically, as will current imbalance. If this imbalance exceeds a pre-determined value, a circuit breaker should operate. Restricted earth fault protection is a type of earth fault protection which looks for earth fault between two sets current transformers[4] (hence restricted to that zone).

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Distance (impedance relay)– Distance protection detects both voltage and current. A fault on a circuit will generally create a sag in the voltage level. If the ratio of voltage to current measured at the relay terminals, which equates to impedance, lands within a predetermined level the circuit breaker will operate. This is useful for reasonable length lines, lines longer than 10 miles, because its operating characteristics are based on the line characteristics

Back-up – The objective of protection is to remove only the affected portion of plant and nothing else. A circuit breaker or protection relay may fail to operate. In important systems, a failure of primary protection will usually result in the operation of back-up protection. Remote back-up protection will generally remove both the affected and unaffected items of plant to clear the fault. Local back-up protection will remove the affected items of the plant to clear the fault.

Low-voltage networks – The low-voltage network generally relies upon fuses or low-voltage circuit breakers to remove both overload and earth faults.

Performance measures

Protection engineers define dependability as the tendency of the protection system to operate correctly for in-zone faults. They define security as the tendency not to operate for out-of-zone faults. Both dependability and security are reliability issues. Fault tree analysis is one tool with which a protection engineer can compare the relative reliability of proposed protection schemes. Quantifying protection reliability is important for making the best decisions on improving a protection system, managing dependability versus security tradeoffs, and getting the best results for the least money. A quantitative understanding is essential in the competitive utility industry. [8][9]

Performance and design criteria for system-protection devices include reliability, selectivity, speed, cost, and simplicity.[10]

Reliability: Devices must function consistently when fault conditions occur, regardless of possibly being idle for months or years. Without this reliability, systems may result in high costly damages.

Selectivity: Devices must avoid unwarranted, false trips. Speed: Devices must function quickly to reduce equipment damage and fault duration,

with only very precise intentional time delays. Economy: Devices must provide maximum protection at minimum cost. Simplicity: Devices must minimize protection circuitry and equipment.

Our project aims to make Ramallah’s network more reliable by increasing the power factor and the voltage levels to reduce the losses and the penalty which comes from the low power factor.

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1.7 Constrains

In our project we faced many constrains such as:

No one line diagram for the net work so we had to built the net work by our self using the Excel which we were given.

The cost of the capacitor bank we were not be capable to be a wear. A lot of time and hard work were needed. Geographical problems. Political problems. The company use IEC standard. We faced a lot of problem with the cables.

1.8 Standard/ Code:

In this project we used the International Electrotechnical Commission “IEC” just like the company used it, IEC standards cover a vast range of technologies from power generation, transmission and distribution to home appliances and office equipment, semiconductors, fiber optics, batteries, solar energy, nanotechnology and marine energy as well as many others. The IEC also manages three global conformity assessment systems that certify whether equipment, system or components conform to its International Standards.

IEC standards have numbers in the range 60000–79999 and their titles take a form such as IEC 60417: Graphical symbols for use on equipment. The numbers of older IEC standards were converted in 1997 by adding 60000, for example IEC 27 became IEC 60027.

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1.9 Methodology

We start our project by building the on line diagram of the network that we analyzed it on its max. And min. Conditions, after that we improved these conditions using:

Increasing the swing bus voltage by 10%. Increasing the tern’s ratio of the transformer by 5%. Adding capacitor banks.

To increase the power factor and the voltage levels to reduce the power losses.

In the maximum load stage we fill the network component as like in the real-time then we analyzed the network -by using the power programs- the voltages in the buses and the losses of the active and reactive power in the network and the power factor in each bus.

In the minimum load stage, the load will decrease by 65% from the maximum load so the voltage will decrease from the nominal value in the small ratio we can improve it by increasing the swing bus voltage in some cases we need a capacitor bank.

Then we mad protection system for a few elements to increase the reliability of the network. Then we made an economical study in order to decide whether our decision well fit or not.

2.1 Analysis Maximum Condition Page | 17

After first run on ETAP, the network condition was as the following figures and tables.

Singel, Deer-Jreer, Silwad and Biteen substations.

` Fig 2.1

Tahounah, Ramallah North and Terah substations.

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Fig 2.2

Silvana, Ramallah City and Kharbatha substations.

Fig 2.3

Al-Moalmeen, Qalandia con. and Tri-fitness substations.

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Fig 2.4

Nabi-Saleh substation.

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Fig 2.5

Atarot main connection point.

Fig 2.6

2.2 Improving Maximum Condition

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After improved on ETAP, the network condition was as the following figures and table.


Fig 2.7

Tahounah, Ramallah North and Terah substation

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Fig 2.8


Fig 2.9

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Silvana, Ramallah City and Kharbatha substations.

Fig 2.10

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Fig 2.11


Fig 2.12

2.3 Maximum Condition Results

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Table 2.1: The voltages before and after improved of Maximum condition.

Bus Name Before After

Rated Voltage (KV) Voltage (KV)Al-Moalmeen 33.0 31.42 33.18Al-Ram 33.0 32.61 34.22Al-Rehan 33.0 30.85 32.72Biteen 6.6 6.60 6.51 6.90Biteen central 33.0 32.76 34.45Biteen west 33.0 31.90 33.66Bus5 11.0 10.32 11.03Bus6 33.0 32.54 34.19Deer Jreer 33.0 34.29 35.49Grand 11 11.0 10.53 11.18Jreer 11 11.0 11.22 11.75Kharbatha 11 11.0 10.51 11.21Kharbatha 33.0 32.34 34.08Rehan 11 11.0 10.19 10.89Moalmeen 11 11.0 10.24 10.96Nabi-Saleh 11.0 10.73 11.39Qalandia 33.0 32.89 34.56Ramallah 11 11.0 10.24 11.00Ramallah City 33.0 32.44 34.10Ramallah North 33.0 31.50 33.33Singel 11 11.0 11.56 11.80Silwad 11 11.0 11.14 11.69Silvana 33.0 32.44 34.08Silvana 11 11.0 10.53 11.19Silwad 33.0 33.70 35.08single 33.0 35.41 35.83Tahona11 11.0 10.25 11.08Al-Tahounah 33.0 31.55 33.46Terah11 11.0 10.45 11.06Al-Terah 33.0 31.99 33.64Tri-fitness 33.0 30.77 32.59Tri-load 11.0 9.98 10.73

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Here are a few numbers of power factors that we have chosen and for more information you can see at the end of reports.

Table 2.2: The power factor state before and after improving.

Bus name Before P.F (lagging) % After P.F (lagging)%

Silwad 89.2 94.8Biteen west 88.0 93.6Singel 87.4 97.5Jreer 83.7 94.1moalmeen 83.4 94.7Ramallah city 89.4 93.0Nabi-Saleh 88.1 92.1Ramallah North 89.8 96.0Tahounah 87.7 93.8Tri-fitness 89.8 95.7Terah 88.5 92.3Qalandia 87.7 94.0Silvana 88.9 91.9AL-Ram 88.7 94.5

Table 2.3: The total demand and losses for maximum cond. before and after imp.

Before After

Total demand (MW) 113.9 121.91Total demand (MVAr) 62.01 45.76Total demand (MVA) 129.68 130.21P.F % 87.8 lagging 93.6 laggingApparent losses (MW) 4.808 3.55

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3.1 Analysis Minimum condition

After first run on ETAP, the network condition was as the following figures and tables.


Fig 3.1

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Tahounah, Ramallah North and Terah substations.

Fig 3.2

Silvana, Ramallah City, AL-Ram con. and Kharbatha substations.

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Fig 3.3


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Fig 3.4


Fig 3.5


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Fig 3.6

3.2 Improving Minimum Condition

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After improved on ETAP, the network condition was as the following figures and table.


Fig 3.7

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Tahounah, Ramallah North and Terah substation

Fig 3.8


fig 3.9

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Silvana, Ramallah City, AL-Ram con. and Kharbatha substations.

Fig 3.10

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Fig 3.11


Fig 3.12

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3.3 Minimum Condition Results

Table 3.1: The voltages before and after improved for minimum condition

Bus Name Before After

Rated Voltage (KV) Voltage (KV)Al-Moalmeen 33.0 32.06 33.72Al-Ram 33.0 32.77 34.42Al-Rehan 33.0 31.68 33.29Biteen 6.6 6.6 6.59 6.88Biteen central 33.0 33.0 34.34Biteen west 33.0 32.45 33.87Bus5 11.0 10.6 11.21Bus6 33.0 32.87 34.30Deer Jreer 33.0 35.06 34.89Grand 11 11.0 10.72 11.32Jreer 11 11.0 11.54 11.62Kharbatha 11 11.0 10.73 11.32Kharbatha 33.0 32.74 34.17Rehan 11 11.0 10.5 11.11Moalmeen 11 11.0 10.56 11.17Nabi-Saleh 11.0 10.82 11.47Qalandia 33.0 32.93 34.58Ramallah 11 11.0 10.53 11.42Ramallah City 33.0 32.72 34.25Ramallah North 33.0 32.11 33.69Singel 11 11.0 12.01 11.59Silwad 11 11.0 11.38 11.60Silvana 33.0 32.72 34.24Silvana 11 11.0 10.72 11.32Silwad 33.0 34.32 34.74single 33.0 36.52 35.17Tahona11 11.0 10.54 11.18Al-Tahounah 33.0 32.14 33.79Terah11 11.0 10.67 11.22Al-Terah 33.0 32.42 33.85Tri-fitness 33.0 31.49 33.10Tri-load 11.0 10.31 10.93

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Here are a few numbers of power factors that we have chosen and for more information you can see at the end of reports

Table 3.2: The power factor state before and after improving.

Bus name Before (lagging) After(lagging)

Silwad 88.6 94.2Biteen west 88.5 94.2Singel 87.4 95.6Jreer 84.1 94.4moalmeen 74.3 91.5Ramallah city 89.1 93.4Nabi-Saleh 88.7 94.1Ramallah North 89.8 94.8Tahounah 89.0 95.2Tri-fitness 89.8 94.1Terah 89.0 92.4Qalandia 88.7 92.4Silvana 91.0 92.3ram 90.0 93.0

Table 3.3: The total demand and losses for minimum cond. before and after imp.

Before After

Total demand (MW) 77.0 82.37Total demand (MVAr) 40.5 31.76Total demand (MVA) 86.98 88.28P.F % 88.5 lagging 93.3 laggingApparent losses (MW) 2.63 1.72

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4. Powers-System Protection

Power transformer protection

The faults that might happen on the transformer:

Short circuit on transformer windings Phase to phase Over load

Protection that might be used in the transformer:

Differential protection to protect the transformer from phase to phase fault. Bucholz protection for inter turn faults. Thermal protection for over load. Erath fault protection from phase to ground faults. Short circuit to protect at internal faults.

For the power transformer we made the differential protection on three transformers the equation were used to calculate the value of the circuit breakers

IC.B>= K*I max load

VC.B>=System

I breaking>=K*IS.C

Note:

K=factor of safety

Isc=sort circuit current.

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The first transformer is at al Nabi-Saleh connection point the transformer changes from (33-11)KV

Fig 4.1

Circuit breaker calculation:

Fault (1) before the transformer

Imax=123 A

Sbase= 7.5Mva

Page | 40

G imp= .1 pu

Vbase= 33Jv

TL length= 3km

Ztl= .65 ohm/km

TR imp= 0.07

Ibase=(Sbase)/(V*sqrt(3))= 131.2 A

Zbase=(V^2)/Sbase= 145.2 ohm

Ztl=(.65*3km)/145.2= .013 pu

Zeq=.1+.013= .113 pu

Isc=1/.113= 8.85 pu

Isc=8.85*131.2= 1160 A

Icb=K*Imax=1.2*123=148 A

Vcb>=Vsys

Ibc=1.2*Isc=1.2*1160=1392 A

Fault(2) after the transformer

Same condition but

Imax= 369 A

Vbase= 11 Kv

Xtr=.07*(sbase/snom)

=0.07*(7.5/15)= 0.035

Zeq=.035+.013=.148 pu

Ibase=Sbase/v*sqrt(3)= 394 A

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Isc=1/.148= 6.8 pu

Isc=6.8*394=2662 A

Icb=1.2*Imax=1.2*369= 443 A

Ibc=1.2*Isc=1.2*2662=3195 A

Fig 4.2

The transformer after adding the CB

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The second calculation for al moalmeen transformers

Fig 4.3

Fault (1) before transformer T8& fault (2) before T4

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Calculation:

Same ways as we did in anabi saleh unit the only difference is that we have double transmission line.

I base=S/(V*sqrt(3))=927 A

Z base=V^2/S=20.5 ohm

Zeq=.43 pu

I sc=1/.43 =2.23

I sc1=I sc2=2.32*927=2156 A

I cb 1=1.2* Imax=1.2*64=77 A

I cb 2=1.2*96=115 A

I bc 1=1.2*2156=2587 A

I bc 2=1.2*2156= 2587 A

* Fault (3) after T_15 MVA:

Same calculation but different in Z eq.

Z eq = .43+(.07*10/53)= .443

I sc= 1/.443= 2.26

I base= 53/11*sqrt(3)=2782

I sc= 2.26*2782=6288 A

I cb= 1.2* Imax=1.2*288=346

I bc= 1.2* Isc =7545

*Fault after T_10Mva

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Z eq = .43+(.07*15/53)= .45

I sc= 1/.45= 2.22

I base= 53/11*sqrt(3)=2782

I sc= 2.22*2782=6176 A

I cb= 1.2* Imax=1.2*192= 230 A

I bc= 1.2* Isc =1.2*6176= 7411 A

Fig 4.4

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5. Economical study

In the economic study do it to know how our design of improving the network is economic feasible and to know how long the payback period of our design.

The payback period method compares the losses power before improvement with the cost of the capacitors we used to improve the condition.

The following calculation illustrates an economical study in four conditions after improvement.

Saving in penalties:

- P max=122 MW.

- P min=82 MW

- Losses before improvement=4.8 MW

- Losses after improvement=3.5 MW

- P.F before improvement=87.8

- P.F after improvement=93.6

- P av=( P min+ P max)/2= 102 MW.

- Total energy per year=P av*8760= 893520 MWH.

- Total cost per year=Total energy*cost(NIS/KWH)

= 893520*0.5

= 446760000 NIS/year.

- Saving in penalties of P.F= 0.01*(.93-0.87.8)*Total cost of energy

= 26805.6 NIS/year.

Saving in losses:

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-Average losses before improvement =3.72MW.

- Energy of the losses before improvement=3.72*8760=32543.4 MWH.

- Cost of losses before improvement= 32543400*0.5=16271700 NIS/year.

- Average losses after improvement =2.63MW

- Energy of the losses after improvement=2.63*8760=23083MWH.

- Cost of losses after improvement=32083000*0.5=11541300 NIS/year.

- Saving in losses= cost of losses before –cost of losses after

= 16271700-11541300= 4730400 NIS/year.

Simple Pay Back Period:

- Total fixed capacitor banks using in maximum case=10.45MVaR.

- Cost per KVAR= 3JD=15NIS.

- Total regulated capacitor banks using in maximum case=9MVAR.

- Cost per KVAR= 15JD=75NIS.

- Total cost of capacitor banks= (75*9000) + (10450*15) =831750 NIS.

- Total saving=saving in losses +saving in penalties

= 4757205NIS.

- S.P.B.P=Investment /Saving

= 4757205/831750= 5.7 years.

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Conclusion:

In maximum condition we improved the power factor more than 92%, in order of that the bills are reduced.

The voltages for all busses are increased above the nominal. The power losses are reduced. Tow stations are protected by using C.B. When the power losses are reduced we saved about 115 M NIS. We added C.B fixed and regulated and the payback period is 5.7 years.

Recommendations:

I noticed that the cables are replaced with transmission lines so we misses the chance to get a leading power factor.

Also we have to raise the power incoming from connection points to enhance the reliability.

At the end I hope the companies we deal with them gets less formally when sharing information with us, also takes our improved networks in serious, that can happen when we see our project applied on the ground.

Trust Palestinian engineers because we are the future..

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