Finaly TPS report

(Genco-III) Northern Power Generation Company Limited1 | P a g e


PREFACE

Practice makes a man perfect and practical knowledge is essential in order to

introducing with the practical life. Theoretical knowledge is not such

important without with combination of practical knowledge. It is the part of

its academic curriculum to do internship of BSc Electrical Engineering &

Technology student to various Engineering concerns with view to allowing

students to get opportunity to acquire practical and professional knowledge.

This report was also assigned the task of preparing the term paper, the topic

was “(Genco-III) Northern Power Generation Company Limited”. To adjust

myself in such a large organization was not an easy task, but by the grace of

Almighty Allah aids my internship in a befitting manner and I learned a lot

about the overall generation company. The report has been prepared after

careful observation of the all component of organization. This report is a

thorough essence of my rigorous studies which I undergone through in a

period of four months in a generation company. I have exclusively studied and

observed the operations/ functioning of the company and tried my best to

abreast myself with all the dimensions of the generation company. It was a

great experience to work there and contribute handsomely in the process of

appraising its pros and cons and feeling to be a significant part of the

company. I am thankful to all those who helped me in one-way or the other

and guided me in the preparation and compilation of this report in a

presentable fashion.


ACKNOWLEDGEMENT

Success and achievement is possible only through hard work, determination and

strong will. We are grateful to ALLMIGHTY ALLAH who gave me the strength to

think, plan and act accordingly which make us possible to complete my internship.

Though it is a literary tradition to acknowledge the contribution and help by different

people and organization in the completion of an internship, but as a matter of fact

some words cannot express our gratitude to the various helping hands. It is very

difficult to appreciate each and every person for his contribution, but there is a

standing contribution of our advisor Sir Muhammad Arshad Bhatti sb, who was

there with us at the time we needed him and without his guidelines it would be

difficult for us to complete this internship successfully.

Thanks to all


DEDICATION

At first dedicating this work to Almighty ALLAH, without his

mercy and sympathy I was not able to accomplish this work,

Almighty ALLAH gave me power and confidence to done my

internship and also HOLY PROPHET HAZARAT MUHAMMAD

(Peace Be upon Him) who is a light for humanity. I also dedicate

this work to my lovely parents with deepest gratitude whose love

and prayers have always been a source of strength for me.


TABLE OF CONTENTS

Contents Numbers

1. Executive Summary--------------------------------------------------------------------------------------4

2. Introduction of Wapda-----------------------------------------------------------------------------------5

3. Pakistan Electric Power Company---------------------------------------------------------------------7

4. Thermal Generation---------------------------------------------------------------------------------------10

5. Background-------------------------------------------------------------------------------------------------16

6. Introduction-------------------------------------------------------------------------------------------------17

7. Objectives---------------------------------------------------------------------------------------------------18

8. Goals----------------------------------------------------------------------------------------------------------

20

9. Chapter 1:

Introduction----------------------------------------------------------------21 1.1. Thermal Generation In Pakistan -----------------------------------------------------------21

1.2. TPS Genco-III-----------------------------------------------------------------------------------22

1.3. Power Plant Overview-----------------------------------------------------------------------23

10. Chapter 2:

Power Plant Operation------------------------------------------------------24 2.1. Single Line

Diagram--------------------------------------------------------------------------------------24

2.2. Boiler & its

Parts---------------------------------------------------------------------------------------25

2.3. Steam Turbine & its

Parts-----------------------------------------------------------------------------26

2.4.

Condenser-----------------------------------------------------------------------------------------------28

2.5. Hot

Well-------------------------------------------------------------------------------------------------29

2.6. Make-up Water

Connection---------------------------------------------------------------------------29

2.7. Condensate

pump---------------------------------------------------------------------------------------29

2.8. Main

Ejector---------------------------------------------------------------------------------------------29


2.9. Vent Steam

Condenser--------------------------------------------------------------------------------30

2.10. LP Heater #

1--------------------------------------------------------------------------------------------30

2.11. Gland Steam

Condenser--------------------------------------------------------------------------------30

2.12. LP Heater #

2-------------------------------------------------------------------------------------------30

2.13. LP Heater #

3-------------------------------------------------------------------------------------------30

2.14. LP Heater #

4-------------------------------------------------------------------------------------------30

2.15. Deaerator

Tank-----------------------------------------------------------------------------------------30

2.16. Feed Water

Pumps-------------------------------------------------------------------------------------31

2.17. HP Heater #

5------------------------------------------------------------------------------------------31

2.18. HP Heater #

6------------------------------------------------------------------------------------------31

2.19. HP Heater #

7------------------------------------------------------------------------------------------31

11. Chapter 3:

Water Feeding

System--------------------------------------------------------------------------------------------32

3.1. Water Feeding

Source--------------------------------------------------------------------------------------------------32

3.2. Condenser Cooling

System---------------------------------------------------------------------------------------------32

3.3. Water Purification

System----------------------------------------------------------------------------------------------33

12. Chapter 4:

Power Plant

Fuel--------------------------------------------------------------------------------------------------------36

4.1. Fuil Oil

Facilities----------------------------------------------------------------------------------------------------------36

4.2. Oil Feeding

System--------------------------------------------------------------------------------------------------------36

4.3. Diesel Oil

Tanks----------------------------------------------------------------------------------------------------------37


4.4. Fuel

Requirements--------------------------------------------------------------------------------------------------------37

13. Chapter 5:

Electricity

Generation-------------------------------------------------------------------------------------------------38

5.1. Main

Generators--------------------------------------------------------------------------------------------------------38

5.2. Excitation Control

System-----------------------------------------------------------------------------------------------38

5.3. Main

Transformers-------------------------------------------------------------------------------------------------------43

5.4. Auxiliary

Transformers-----------.--------------------------------------------------------------------------------------47

5.5. Main Auxiliary

Equipments---------------------------------------------------------------------------------------------48

5.6. Auxiliary Control

System------------------------------------------------------------------------------------------------49

14. Chapter 6:

220kv Switch

Yard---------------------------------------------------------------------------------------------------49

6.1. Busbar

System----------------------------------------------------------------------------------------------------------49

6.2.

Isolators--------------------------------------------------------------------------------------------------------------------50

6.3. Circuit Breakers

----------------------------------------------------------------------------------------------------------51

6.4. PT (potential transformer)

----------------------------------------------------------------------------------------------53

6.5. CT (current Transformer)

-----------------------------------------------------------------------------------------------54

6.6. Surge

Arrestors-----------------------------------------------------------------------------------------------------------55

6.7. Control

System-----------------------------------------------------------------------------------------------------------56

15. Swot Analyses -----------------------------------------------------------------------------------------------------------------------------------------------------62

16.

Recommendations------------------------------------------------------------------------------------------------------------------------------------------------67

17.

Conclusion----------------------------------------------------------------------------------------------------------------------------------------------------------------68


EXECUTIVE SUMMARY

According to internship requirement, I passed Four (4) Months at Genco from Feb 1st,2016 to

May 31,2016. This was so much learning period for me. This internship report is about

Thermal Power Station Muzaffargarh also named as GENCO_III. In GENCO_III ,there are

total 6 units in which Phase-I consists of 3 units of 210MW each and Phase-II consists of 2

units of 210MW each and a separate unit namely unit-IV having a capacity of 320MW.So a

total of 1,370MW capacity of GENCO-III. The generators installed are all furnace oil

generators consisting of a steam turbine and having water tube Boiler. In this report, different

protections of generator and transformers are discussed. The circuit Breakers and their types

and relays and the role of instrument transformer are discussed. The importance of

switchyard is given in detail.

In this report I give introduction history of the Genco. In this report I did SWOT analyses,

financial analyses, projects of Genco and projects which I did in Genco. This project gives to

me as assignment which is also helpful for the organization. So I give some recommendations

and conclusion at the end.


INTRODUCTION OF WAPDA

WAPDA, the Pakistan Water and Power Development Authority, was created in 1958 as a

Semi-Autonomous Body for the purpose of coordinating and giving a unified direction to the

development of schemes in Water and Power Sectors, which were previously being dealt

with, by the respective Electricity and Irrigation Department of the Provinces.

Since October 2007, WAPDA has been bifurcated into two distinct entities i.e. WAPDA and

Pakistan Electric Power Company (PEPCO). WAPDA is responsible for water and

hydropower development whereas PEPCO is vested with the responsibility of thermal power

generation, transmission, distribution and billing. There is an independent Chairman and MD

(PEPCO) replacing Chairman WAPDA and Member (Power) who was previously holding the

additional charges of these posts.

WAPDA is now fully responsible for the development of Hydel Power and Water

Sector Projects.

PEPCO has been fully empowered and is responsible for the management of all the

affairs of corporatized nine Distribution Companies (DISCOs), four Generation

Companies (GENCOs) and a National Transmission Dispatch Company (NTDC).

These companies are working under independent Board of Directors (Chairman and

some Directors are from Private Sectors).

The Companies are administratively autonomous and leading to financial autonomy

by restructuring their balance sheets by bringing their equity position to at least 20

percent, required to meet the prudential regulations and to facilitate financing from

commercial sector (approved by ECC).

The Loan Liability Transfer Agreements (LLTA) has been signed with Corporate

Entities and execution of loan transfer is complete.


All Entities have the physical possessions of all their operational assets.

On 24th Feb. 2007 Ministry of Water & Power notified NEPRA approved Tariff for

all Distribution Companies replacing unified WAPDA Tariff.

Legal Agreements such as Business Transfer Agreements, Operation Development

Agreement, Energy Supply Agreement, Business Supplementary Agreement and

Fuel Supply Agreement etc. were executed between WAPDA and Corporate Entities

to facilitate commercial operations.

Regulatory instruments like Grid Code, Distribution Codes, Performance Standard

for Distribution Companies and Transmission Companies were drafted and got

approved from in 2007.

All major lenders gave their consent for transfer of their loan from WAPDA to

Corporate Entities, thus 326 loan assumption agreements were signed amongst

respective Companies, WAPDA and EAD (Economic Affairs Division) GOP.

CPPA is established under the coverage of NTDC for payments from DISCOs to

IPPs, GENCOs and NTDC. Ultimately, it will function independently under Federal

Govt. and all forthcoming IPPs will be under CPPA.

The Charter of Duties of WAPDA is to investigate, plan and execute schemes for the

following fields:

Generation, Transmission and Distribution of Power.

Irrigation, Water Supply and Drainage.

Prevention of Water logging and Reclamation of Waterlogged and Saline Lands.

Flood Management.

Inland Navigation.

The Authority comprises of a Chairman and three (3) Members working through a Secretary.

WAPDA is one of the largest employers of human resources in Pakistan. It has 150,000

employees, which make it 2nd largest organization of Pakistan, after Pakistan army. Over the

years WAPDA has built-up a reservoir of Technical know-how and expertise which has made

it a modern and progressive organization.

WATER WING


In 1959, WAPDA was created to undertake the task of investigating, planning and

executing schemes for irrigation, drainage, prevention of water logging and reclamation

of saline land as an autonomous body responsible for integrated development of water

and power resources in Pakistan. The organization was also entrusted with the work of

implementing Indus Basin Settlement Plan signed between India and Pakistan in 1960

to develop replacement works for management of river water and irrigation system.

Since then it has been engaged in building water development projects which include

extensive research and investigation to augment country's water resources.

POWER WING

Power Wing is currently headed by

Member (Power) PEPCO.

PAKISTAN ELECTRIC POWER COMPANYThe Pakistan Electric Power Company (Private) Limited (PEPCO) has been entrusted the

task of managing the transition of WAPDA from a bureaucratic structure to a corporate,

commercially viable and productive entity. It is a mammoth task and progress in the initial

months was rather slow, but one should keep in mind that responsibility is enormous and

transition is a long drawn process.

Before going into further details of the restructuring program, it is necessary to understand


the shift in the GoP policy. The GoP, in line with its Strategic Plan of 1992 approved by the

cabinet committee, had decided to restructure the entire power sector in the country

De-regulation of power sector

Promotion of IPPs

Restructuring of WAPDA

Privatization of select corporate entities

The factors responsible for the shift in policies were: generation capacity could not be

increased to meet demand; WAPDA's growth caused inefficiencies, 'demand suppression' and

high tariff policy, proliferated theft. All these factors, over the years, adversely affected

WAPDA's financial condition. As part of this program WAPDA's functions under its Water

Wing and Power Wing were to be segregated. It was previously envisaged that all power

generation, hydel as well as thermal, would be corporatized. However, later on it was decided

that the hydel generation should remain part of the Water Wing or the remaining WAPDA.

PEPCO has prepared the conceptual framework and is following a comprehensive strategy

whereby WAPDA's vertical-monolithic Power Wing has been restructured into twelve (12)

distinct autonomous entities under Companies Ordinance 1984. These are: three generation,

one transmission and eight distribution corporate entities

The restructuring program of WAPDA's Power Wing is based on the new strategic policies of

the GOP and endorsed and supported by the donor institutions. The aim of this transition is to

install corporate and business culture through: adopting of good business practices, enhancing

productivity and efficiency, including customer orientation and service culture, improving

quality of services setting performance targets, reducing costs, theft and wastage. This will be

based on extensive use of information technology, management information systems,

monitoring and prudent decision making.

It has been decided that some of the functions currently being performed by WAPDA will

continue to remain with WAPDA/GoP in the largest interest of the country.

These are:

Hydel development


Hydel operation

It was also decided that some of the common facilities, being previously shared by the two

wings and by various departments within the power wing, should be segregated. These would

initially remain with WAPDA unless transferred to any other particular corporatized entity.

These facilities include hospitals, schools, training facilities etc.

ACCOMPLISHMENTSMajor accomplishments to-date is as follows:

Operationalized Pakistan Electric Power Company (PEPCO) as a Private limited management

company owned by Government of Pakistan (GOP) to steer, manage and oversee the

corporatization/commercialization reforms program.

Formed fourteen (14) Corporate Entities as following:

Four (4) Thermal Power Generation Companies (GENCOs)

One (1) National Transmission & Power Dispatch Company (NTDC)

Nine (9) Distribution Companies (DISCOs)

Constituted Board of Directors of the corporate entities with the induction of

Directors from the private sector and PEPCO to utilize their experience for

formulation of effective corporate policies.

Executed Legal agreements such as Business Transfer Agreements (BTA), Operation

and Development Agreement (ODA), Electricity Supply Agreements (ESA), Bulk

Supply Agreements (BSA) and Fuel Supply Agreements (FSA) between WAPDA

and corporate entities for autonomous commercial operation.

Transfer of WAPDA staff to the respective corporate entities (Manpower Transition

Program Phase-I completed). Phase II is scheduled for completion by June, 2000.

Obtained Federal Tax Exemptions for the corporate entities for Capital Value Tax,

Income tax and Wealth Tax.

Obtained consent of most of the creditors.

Prepared, reviewed, approved and adopted opening Balance Sheets of the corporate

entities as of 30-06-1998.


Privatization schedule for Faisalabad Electric Supply Company (FESCO) finalized &

sent to the Privatization Commission of Pakistan

Investment Plans for Distribution Power System Rehabilitation prepared and

finalized by the Distribution companies

Financial Restructuring of WAPDA approved by GOP

Filed applications by all Power Distribution Companies (DISCOs) for obtaining

License from National Electric Power Regulatory Authority (NEPRA). Public

hearing by NEPRA for processing of applications of Lahore Electric Power Supply

Company (LESCO) and Gujranwala Electric Power Company (GEPCO) completed

Submitted proposal to GOP for Price consideration to be paid or settled by GOP with

WAPDA so that share of the corporate entities owned by WAPDA can be transferred

in the name of GOP.

THERMAL GENERATIONPEPCO's Thermal Power Generation is mainly based on generation of power from its Steam

Turbo-Generators, Gas Turbines (simple as well as Combined Cycle Units) installed at

different Power Stations located in Sindh, Punjab and Baluchistan provinces. Indigenous Gas

& Coal is the main fuel whereas Furnace oil and HSD are also used as alternative fuel. .


As per Government of Pakistan policy all thermal power generation has been restructured and

four corporatized companies namely Jamshoro Power Generation Company Limited

(GENCO-1) head quarter at Jamshoro district Dadu near Hyderabad Sindh, Central Power

Generation Company Limited (GENCO-2) head quarter at Guddu district Jacobabad Sindh

and Northern Power Generation Company Limited (GENCO-3) headquarters at Muzaffargarh

and Lakhra Power Generation Company Limited (GENCO-IV) at Khanote (Sindh) have been

formed and registered. Functioning of GENCOs has commenced.

Structural formation of all four GENCOs is as under:

JPCL

(GENCO-1)

CPGCL

(GENCO-2)

NPGCL

(GENCO-3)

LPGCL

(GENCO-4)

TPS Jamshoro TPS Guddu TPS Muzaffargarh FBC Lakhra

GTPS Kotri TPS Quetta NGPS Multan

TPS GUDDU

a. Location

Thermal Power Station Guddu is situated on the right bank of River Indus near Guddu

barrage, 10 Km from Kashmore in district Jacobabad (Sindh). It is about 60 Km away from

Sadiqabad and about 160 Km from Sukkur. It is a confluence of three provinces, i.e. Sindh,

Punjab and Baluchistan.

b. Fuel (Gas & F. Oil) Supplies

The existing daily gas allocation is 285 MMCFD, (from Kandhkot = 115 MMCFD, Sui = 40

MMCFD Mari=90 MMCFD & Tullow= 40 MMCFD). Daily requirement of gas is about 310

MMCFD and in this way there is short fall of about 25 MMCFD. Furnace Oil is also used to

meet-with short fall of Gas quota. Furnace oil is received through Railway Wagons and Tank

Lorries from Karachi.

TPS QUETTA

a. Location


This Power Station is situated at Quetta.

b. Fuel (Gas) Supplies

Natural gas is the main fuel being used for combustion as and when available basis. Company

under the new management (PEPCO) is trying to make an agreement with the gas company

regarding firm gas supply.

TPS MUZAFFARGARH

a. Location

TPS Muzaffargarh is located in the middle of the country between the River Indus and River

Chenab, 2.5 Km to North-West of Muzaffargarh Town in District Muzaffargarh. The nearest

Airport facility is at Multan at a distance of 45 Km North-East of Muzaffargarh.

b. Fuel

Dual fuel combustion provision (Gas & Furnace Oil) has been made for all the machines.

Furnace oil is transported through Railway Wagons and tank Lorries.

NGPS MULTAN

a. Location

Power Station is located at Piranghaib about one Km towards North from Piranghaib Railway

station and at a distance of 10 Km from Multan city towards East.

b. Fuel

Dual fuel combustion provision (Gas & Furnace Oil) has been made for all the machines. 15

MMCFD gas is allocated and the short fall is met with by furnace oil firing.

SPS FAISALABAD

a. Location

This Power Station is situated at about 10 Km from Faisalabad city on Faisalabad-

Sheikhupura road. Nishatabad railway station is 04 Km in the West and Rakh branch canal

flows close to the power station in the East.

b. Fuel


Dual fuel combustion provision (Gas & Furnace Oil) has been made for all the machines.

Requirement of Gas on 70% load factor is about 22 MMCFD.

GTPS FAISALABAD

a. Location

This Power Station is situated (adjoining SPS) at about 10 Km from Faisalabad city on

Faisalabad-Sheikhupura road. Nishatabad railway station is 04 Km in the West and Rakh

branch canal flows close to the power station in the East.

b. Fuel

Dual fuel combustion provision (Gas & HSD Oil) has been made for all the machines.

GTPS SHAHDARA

a.Location

This Power Station is situated at Shahdara on right bank of river Ravi Lahore.

b. Fuel (Gas) Supplies

Natural gas is the main fuel being used for combustion as and when available basis. Company

under the new management (PEPCO) is trying to make an agreement with the gas company

regarding firm gas supply.

FBC LAKHRA

a. Location

The Lakhra Power Station is located near Manzoor-abad/Khanote in the District of Dadu

(Sindh) on the right bank of mighty Indus River. Hyderabad city is about 46 Km in North-

East and Karachi is about 200 Km South-West of the Power Plant. The Power Station can be

readily approached from North and South by the connecting highways.

b. Fuel

All the three units are based on Coal, which is being recovered by primitive underground

mining method from Lakhra coal mines, 25 Km from Lakhra Power Station.

The detail of three GENCOs showing Power stations, number of units installed, capacity,

make, year of commissioning and fuel used is given below in table-1, 2, 3&4.




To make Pakistan Power Sector customer friendly, efficient, able and responsive in meeting tee electric energy requirements of industry, business and domestic customers, and move to an energy sufficient model from the current energy deficient scenario, on commercially viable and sustainable basis, in order to support the high growth economy and to meet the government's objective of "Power for All".VISIONMISSION

GENERATION COMPANIES Jamshoro Power Company Limited (JPCL) GENCO I

Central Power Generation Company Limited (CPGCL) GENCO II

Northern Power Generation Company Limited (NPGCL) GENCO III

Lakhra Power Generation Company Limited (LPGCL) GENCO IV

ONE TRANSMISSION COMPANY National transmission & power dispatch company (NTDC)

EIGHT DISTRIBUTION CORPORATE ENTITIES1. LAHORE ELECTRIC SUPPLY COMPANY LIMITED (LESCO)

2. GUJRANWALA ELECTRIC POWER COMPANY (GEPCO)

3. FAISALABAD ELECTRIC SUPPLY COMPANY (FESCO)

4. ISLAMABAD ELECTRIC SUPPLY COMPANY (IESCO)

5. MULTAN ELECTRIC POWER COMPANY (MEPCO)

6. PESHAWAR ELECTRIC SUPPLY COMPANY (PESCO)

7. HYDERABAD ELECTRIC SUPPLY COMPANY LIMITED (HESCO)

8. QUETTA ELECTRIC SUPPLY COMPANY (QESCO)

(GENCO-III) NORTHERN POWER GENERATION COMPANY LIMITED MISSION STATEMENT

Our mission is to bring the assurance of energy to our customer, with world class

quality and commitment for satisfaction as we in our quest for excellence


http://www.qesco.com.pk/

http://www.hesco.gov.pk/

http://www.pesco.gov.pk/

http://www.mepco.com.pk/

http://www.iesco.com.pk/

http://www.fesco.com.pk/

http://www.gepco.com.pk/

http://www.lesco.gov.pk/

BACKGROUNDNorthern Power Generation Company Limited owns and operates thermal power generation

facilities located at Muzaffargarh, Multan and Faisalabad. Installed capacity of the generating

assets is 1,921 MW, which has declined over the years to dependable capacity of 1,169 MW.

Complex pattern of internal and external factors constrain operating and financial

performance of the company. The company has been operating with a negative bottom line,

which has jeopardized sustainability.

Government of Pakistan aims to address the country’s power sector issues by implementing

Power Sector Reform Program. As part of the program the public sector thermal power

generation companies (GENCOs), including NPGCL were required to develop and implement

Business Plans to effectively respond to constraints and obstacles to satisfactory performance.


INTRODUCTIONThis thermal power station is situated in Multan division’s district Muzaffargarh. In 1985

Gulam Ishaq Khan make an agreement with Russia for the establishment of the power station.

Initially this Project was documented for Multan. But due to certain reasons like availability

of land, cost etc. This project shifted to Muzaffargarh by the name of Multan II. Initially three

units were established in Muzaffargarh, called phase 1. These are also known as Russian

units. These units are operated with Oil & Gas. The each unit is of 210 M.W. capacities.

China establishes their units to meet the need/demand of electricity. These units are also 210

M. Watt.

China has also established a unit called unit #4 witches has the capacity of 320 M. watt. The

unit #4 is fully computerized. All its functionality is handled through computerized programs.

About 1500 people are working in this organization including both technical & non-technical.

To make this project Economic District Muzaffargarh was select. Other Reasons for this

location is that there is no thermal house in this Area at that time the Area like Multan

Division and D.G Khan lies at center of Pakistan approximately. The selection of this location

may be due to safety reason in war conditions.

Pakistan Water and Power Development Authority (WAPDA) is an integrated utility in

Pakistan. WAPDA is responsible for the development of Hydel Power and Water

Sector Projects in Pakistan. WAPDA operates through- Power wing and Water wing, it is

engaged in the generation, transmission and distribution of power. In addition, it also manages

irrigation, water supply and drainage system in the country. Further, it is also responsible for

prevention of water logging and reclamation of waterlogged and saline lands.

The Pakistan Water and Power Development Authority (WAPDA) was established through

an act of parliament in February 1958 for integrated and rapid development and

maintenance of water and power resources of the Country. This includes

controlling soil salinity and water logging to rehabilitate the affected land in

order to strengthen the predominantly agricultural economy of the country. As

per the charter, amended in March 1959 to transfer the existing electricity


departments from the federating units to it, WAPDA has been assigned the duties

of investigation, planning and execution of projects and schemes for:

Generation, Transmission and distribution of power,

Irrigation, water supply and drainage,

Prevention of water logging and reclamation of saline land,

Flood control and Inland navigation.

Under the later on developments, vis-à-vis the “energy policy 1994”, setting up of

thermal power generation projects was shifted to the private sector. Similarly, as a result of re

structuring of the power wing, the utility part was corporatized into independent companies.

This shift from convergence to divergence gave birth to 13 entities to operate in different

zones. These are national transmission and Dispatch Company (ntdc), four thermal

power generation companies (gencos) and eight distribution companies (discos).

The present status of these companies is of corporate public limited entities

under the Umbrella of EPCO, ultimately to go privatized as planned. The

residual Power Wing is therefore now responsible for major hydro-electric power

projects and schemes in operation.

OBJECTIVES


Pakistan Electric Power Company (PEPCO) unveiled new face of Pakistan's power

sector with the crisis management objectives to improve the efficiency of the power

sector and to meet customers' electric energy requirements on a sustainable and

environment friendly basis. The specific objectives of PEPCO are:


Stop load shedding,Revamping of generation units and to improve customer services andConstructing new grid stations,Reducing line losses; minimizing tripping and theft control,Development of an integrated automated power planning system for generation, transmission and distribution to ensure system stability, fault isolation and upgrade relying, metering and tripping system at NTDC as well as Discos level.

GOALSThe following power projects are in pipeline and will be included in GENCO III after their

commissioning.


GOALS

Chapter 1:

INTRODUCTION

1.1. Thermal Generation in PakistanThermal Power Generation in Pakistan is mainly based on generation of power from its Steam Turbo-Generators, Gas Turbines (simple as well as Combined Cycle Units) installed at different Power Stations located in Sindh, Punjab and Balochistan provinces. There are

number of thermal generation companies working inside Pakistan, some of them are working under government of Pakistan and some of them are working privately. Indigenous Gas & Coal is the main fuel whereas Furnace oil and HSD are also used as alternative fuel.Pakistan has a total installed power generation capacity of 22,000 MW in which 71% approx. power is generating by oil and gas fuel. However, the de-rated capacity is in the range of 16,500 to 18,500 MW in the end of 2013.

1.2. TPS GENCO-III

TPS (Thermal Power Station) GENCO-III is a thermal power plant working under the NPGCL (Northern Power Generation Company limited) Pakistan located in Muzaffargarh. In this power plant the Furnace oil is a primary fuel; however the diesel oil and natural gas also used in specific times i.e. natural gas is used at the peak hour load time and diesel oil is used at the time of starting of plant.The total installed capacity of this plant is about 1350MW, but the de-rated capacity is about 1100MW. There are total 6 units installed in this plant and their data is given in the table below. .

Unit No.

InstalledCapacity(MW) Manufacturer Fuel Type

1 210 M/s T.P.E. USSR Natural Gas / Furnace Oil



4 320 M/s CMEC China Natural Gas / Furnace Oil


UnitNo.

InstalledCapacity(MW)

DeratedCapacity(MW)

GeneratingVoltage(KV)

AuxiliaryConsumption(%)

NetCapacity(MW)

PowerFactor

1 210 200 15.75 6 188 0.852 210 200 15.75 6 188 0.853 210 200 15.75 6 188 0.854 320 300 19.75 8 276 0.855 200 200 15.75 9 182 0.856 200 200 15.75 9 182 0.85Total 1350 1300 1204



Total 1350 - -

The capacity in the above table is the installed capacity of these units. Some of their capacity decreased with the passage of time. This decreased capacity of generator is known as de-rated capacity. Also some capacity is used by system’s auxiliary units. The net capacity of the system is given in the next table.

1.3. Power Plant Overview

In this thermal power station, prime mover is a steam turbine which is further coupled with the power generator. In this power there are two yards e.g. Phase # 1 and Phase # 2.In phase 1 there are four units installed by which 1 st three have the capacity of 210MW and the capacity of fourth unit is 320MW.In this plant chemical energy is converted into heat (by burning fuel in furnace) then heat is converted into mechanical energy(by rotating the turbines) and finally mechanical energy is converted into electrical energy (using generators).The output power of these generators is not enough to transmit directly, so that power is made efficient for transmission by the power step-up transformers. This plant also has a 220kV grid station which is used to export, import power form other power stations according to the requirements.There are four main power lines going outside the switchyard which are:

1- PARCO LINE2- New Multan Line3- KEPCO Line4- Line to 500kv Grid.

The first three lines are used for both import and export power depending upon the load demands while the fourth line is only for export purpose.



Chapter 2:

POWER PLANT OPERATION

2.1. Single Line Diagram

The single line diagram of a single unit is given below.


In the above diagram it has been shown that there is a cycle in which water converted into steam, steam passes through turbine stages to rotate turbine shaft, after passes from turbine stages this steam converted into water and then this water passes boiler to convert it into steam again.

2.2. Boiler & its Parts

A boiler is a closed vessel in which water or other fluid is heated. Generally the boiler has three major parts which are:

1- Chimney2- Furnace 3- Boiler Drum.

There are two major types of boiler which are given below.1- Water Tubes Boiler2- Fire Tubes Boiler

Here we will discuss the 1st type of boiler because in this plant water tubes boilers are used.It consists of many parts some of its importants parts are given below.

2.2.1. Boiler Drum

It separates and stores water and steam. Pressure inside drum is 155kg/cm2 and temperature is 343oC. The steam inside the boiler drum is known as saturated steam because it contain some water vapors or in short it’s not a pure steam.

2.2.2. Super Heater

Super heater is the main heater of the furnace which has a temperature of 1600oC.The saturated steam of boiler drum passes through super heater and its temperature increased to 540oC and has a pressure of 130kgN/cm^2.There are four stages of super heater in the furnace which are:

1- Radiation Super Heater.2- Pattern Super Heater.3- Convection Super Heater.4- Ceiling Super Heater.

The saturated steam enter from first stage and out from 4th stage and becomes a live steam.

2.2.3. Down Comer

Down comer is part of boiler drum it’s placed below from the drum and it stores the hot water which have not yet converted into saturated steam.

2.2.4. Up-Riser Tube


Up-riser tubes are also the part of boiler drum. They are used to take water from down comer through pump and enter into the boiler. Here the water exposed to the high temperature and hence some water converted into saturated steam and the rest of water again fell into the down comer and again up-riser tubes take it to boiler. This cycle remains continue until all the water converted into the saturated steam.

2.2.5. Economizer

Economizer is the initial stage of boiler. It takes heat from the exhaust of furnace and increase the temperature of water. In short economizer is used to increase the efficiency of boiler.

2.2.6. Cyclone

In this part, cyclones are produced to collect silica from the surface of water and remove it from the bottom. Cyclone is located inside the boiler drum and it is also called the steam washer.

2.2.7. Burners

Each furnace consists of 12 burners, 6 on one level and other 6 are on the upper level on the same side of the furnace, since front fire burner scheme s used in these furnaces. A pilot burner is also installed inside the furnace which provides ignition to the burners while the pilot burner is ignited by an electric spark inside the furnace. For ignition, diesel oil or natural gas is used.

2.3. Steam Turbine & its Parts

Turbines are machines which converts potential energy into kinetic energy. It provides rotational motion required by generator to produce electricity at rated frequency. Its diagram is given below.

This turbine is divided into three parts which are:


1- High Pressure Turbine.2- Intermediate pressure Turbine3- Low pressure Turbine.

All these three parts are connected to singe shaft and making a tandem compound. This shaft is further coupled with the generator shaft. Inside the turbine there are so many blades some of them are fixed and some are moveable, they are in curved shape so that steam can rotate the moveable blades. There are total 29 stages of turbine.

1 stage = 2 fixed blades + 1 moveable blade.

1st stage of turbine is impulse turbine and rest stages are reaction turbine. Impulse stage is used to drop the pressure and increase the velocity, so that high pressure can’t harm the other blades.

2.3.1. HPC Turbine

HPC stands for High Pressure Cylinder. It is the part where the steam from the super heater enters to turbine. Here the temperature of live steam is 540C and very high pressure of 130kgN/cm^2. Therefore it is called high pressure turbine. It has 12 stages and 2 extensions.

2.3.2. Re-Heat Steam Cycle.

Steam after passing through the HP turbine drops its temperature to 332C and pressure to 28.1kgN/cm^2 and that steam can’t be feed to IP turbine because of water vapors which can causes of damage the turbine blades. So, at this point the steam re-heated by the re-heater and again its pressure raised to 540C but pressure doesn’t increase because of increasing the area of pipe. The main reason for not increasing the pressure is to creating the pressure difference between the entering point and exit point of HP turbine. If we increase the pressure then there would be no pressure difference and hence steam will stop to flow.

2.3.3. IPC Turbine

IPC (Intermediate pressure cylinder) also called IP turbine, because the pressure is very low.It has 11 stages and all are reaction stages and has 4 extensions. The steam after passing through the re-heater enters into the IP turbine and rotates its shaft. The IP turbine bears the maximum load of generator.

2.3.4. LPC Turbine

LPC turbine is a low pressure turbine. Steam when passes through the IP turbine it temperature fall down from 540C to 168C and pressure from 24.7kgN/m^2 to 1.23kgN/m^2. Because of this low pressure this part of turbine is known is LP turbine. It has 6 stages and only one extension.

2.3.5. Turbine ExtensionsTo increase the efficiency of turbine and reduce the cross section area of turbine there are some extension pipes used to move out the steam from the cylinders of turbine.


Steam when enters into the turbine and move the blades then some of its portion lose the temperature and remain at bottom of cylinder which causes to reduce turbine efficiency. So, this portion of steam moves out from the cylinders by extension pipes and used to warm the water.

2.3.6. Turbine Capacity

As we know that the generator coupled with turbine shaft is of 210MW. So, the capacity of turbine must be equal or more than 210MW. We know that there are three parts of this turbine; each part is used to handle the different load. The turbine data is given in the table below.

Turbine Part No. of Stages No. of extensions Capacity of Load (MW)

HP – Turbine 12 2 60

IP – Turbine 11 4 100

LP - Turbine 6 1 50

2.3.7. Speed Control System

Speed is an important factor of turbine. According to the requirement of the generator the turbine must be able to rotate its shaft at 3000rpm on every load conditions. To control the speed of turbine there are governing valves which are operated by hydraulic pressure. They can be operated by both automatic and manual control. For automatic control system there is a speed meter interfaced inside the turbine and also there is a servo motor which controls the governing valves.

2.4. CondenserA device or unit used to condense vapor into liquid by cooling it is known as condenser. Its diagram is given below


Steam (50oC and very low pressure), after rotating shaft in low pressure turbine reaches to condenser. It is a tank with parallel tubes filled with raw water, coming from cooling towers. Steam strikes with those pipes, loses its latent heat and condenses to water.Condenser is the place where maximum heat loss occurs. Total no. of tubes in this condenser is 16700 tubes. Each tube has 9m length and 28mm diameter length.The condenser cooling surface area is 13180m^2 and its capacity is also 210MW.

2.5. Hot Well

When steam passes through the condenser then it becomes water and that water is stored in the hot well. It is the also known as a storage tank the water in hot well of very low pressure of 0.09kgN/cm^2 and low temperature of 45C.

2.6. Make-Up Water Connection

The pure water from the water-purification plant is added up at the outgoing path of hot well.In a steam cycle the high pressure steam passes through different places and due to leakage at somewhere, its quantity decreased and hence the quantity of pure water for the boiler is also decreased so, the new water added up to fulfill the requirements of boiler.

2.7. Condensate Pump

Condensate pump is used to pick water from the hot well and pump it towards the deaerator tank.It increased the pressure of water from 0.09kgN/cm^2 to 16.2kgN/cm^2. There are 3 condensate pumps at single unit in which 2 pumps work and one is for standby purpose.


2.8. Main Ejector

Main ejector is used to eject non-condensable from water by using vacuum, created due to condensation. Two ejectors are installed. One is operational while other one is for backup use.Its diagram is given below.

Maintaining vacuum at rated pressure is very necessary otherwise efficiency of boiler will drop.

2.9. Vent Steam Condenser

It is used for warming the water. Its steam comes from turbine’s sealing. This is also used for the air ventilation purposes because its steam contains some air. It rise the temperature from 48C to 50C.

2.10. LP Heater # 1

LP heater 1 takes heat from the 7 th extension of LP turbine and heat water. It increases the water temperature from 50C to 64C.

2.11. Gland Steam Condenser

Gland steam condenser performs the same task as vent steam condenser except for the air ventilation because; its steam doesn’t contain air. It increases the water temperature from 64C to 68C.

2.12. LP Heater # 2

LP heater 2 takes heat from the 6th extension of IP turbine and heat water. It increases the water temperature from 68C to 100C.


2.13. LP Heater # 3


2.14. LP Heater # 4


2.15. Deaerator Tank.

Its basic purposes are to remove non-condensable gases (i.e. CO2 and O2) and heating water. These gases cause to make corrosion inside the pipes and also they introduce resistance in the way of water flow. It is installed above the feed water tank. Its diagram is given below.

Water is entered from the top and steam is introduced from the bottom and with the interaction of both, non-condensable gases get heat. Since gases becomes lighter and move in upward direction when they get heat so they collect in the upper portion of deaerator while water drops in a tank called feed water tank.

2.16. Feed Water Pumps.

Feed water pumps are used to take water from feed water tank and pump it towards the boiler.They increased the pressure of water from 82kgN/cm^2 to 190kgN/cm^2. There are 3 condensate pumps at single unit in which 2 pumps work and one is for standby purpose.


2.17. HP Heater # 5

HP heater 5 takes heat from the 3rd extension of IP turbine and heat water. It increases the water temperature from 167C to 182C.

2.18. HP Heater # 6

HP heater 6 takes heat from the 2nd extension of HP turbine and heat water. It increases the water temperature from 182C to 220C.

2.19. HP Heater # 7

HP heater 7 takes heat from the 1st extension of HP turbine and heat water. It increases the water temperature from 220C to 245C. Water after passing through this heater again goes toward the boiler drum; where it again converted into the steam and then this cycle remains continue.


Chapter 3:

WATER FEEDING SYSTEM

3.1. Water Feeding Source

The main water sources are the tube wells which are located at Teleri canal in Muzaffargrh. There are total 16 tube wells feeding two main pipe lines. These pipe lines feed water to the power plant. The water is not only used for the plant but also used for human needs.

3.1.1. Makeup Tank and Pumps.

The water from the tube wells is feed into the storage tank or makeup tank. The capacity of makeup tank is about 4000m^3. At makeup tanks there are 5 makeup pumps which are used for further supply of water to chemical plant and also to forebay tank. Each pump has a pressure of 4kgN/cm^2.

3.2. Condenser Cooling System.

The cooling system of plant plays a vital role in stabilizing the overall system. The block diagram of condenser cooling system is given below.


3.2.1. Forebay Tank.

Forebay is place where the water is stored for condenser cooling. It stores a large amount of water and also there are mechanical filters placed inside it which are used for filtration of water.Water filtration is necessary because the condenser tubes are too thin and impure water can block them which results to decrease the condenser efficiency.

3.2.2. Circulating Pumps.

Circulating pumps are used to pick water from forebay tank and pump it towards the condenser. There are 8 circulating pumps in which 6 pumps are for working and 2 are for standby situation.Each pump has a pressure of 17kgN/cm^2.

3.2.3. Cooling Towers

Cooling towers are used to maintain the temperature of water from the condenser.There are 16 cooling towers for each unit and there are distributed into two sets. Each set has eight fans. In these tower hot water is showering from the top and their fans suck air from the bottom so, that the temperature of water decreased up to 6C.

3.3. Water Purification System.

For the making of steam and for the cooling of generators only the pure H2O water is used because, impure particles in this water causes

1- Vibrations in the turbines and damage its blades.2- Corrosion inside the pipes.3- Electrical conductivity between the generator windings.

To purify the water from makeup tank there is a water treatment plant, where this water passes through different stages to remove its impurities. The block diagram of this plant is given on the next page. The raw water in this plant passes from 6 different stages which are:

1- Mechanical Filters.2- 1stStage of Cation Filter.3- De-Gassifier.4- Anion Filter.5- 2nd Stage of Anion Filter.6- Mixed Bed Filter.

Their description is given on the next page.


3.3.1.Mechanical Filters.

First of all, raw water enters in these filters. Four filters are installed for this purpose, in which two of them are functional while other two are for stand-by use. Each tank has the capacity of 45T/h.


3.3.2. Cation Filter # 1.

To removing the cation salts like ( Ca+2, Mg+2, Na+1 ),this water passes through cation filter, where it interacts with hydrogen ions H+. These hydrogen ions replace the other cations from their salts and removed in this stage. As we can see this equation below

MgSO4 + 2H+ Mg+ + H2SO4

3.3.3. De-Gassifier.

De- gassifier or de- carbonizer are used to remove CO2 gas from the water. For this purpose there are two main chambers where water is showering from the top and air is entered form the bottom by fans. This air interacts with the carbon ions in water and makes CO2 gas, which moves out from the top side of chamber. And the water collected in the storage tank, located below the chamber.

3.3.4. Anion Filter.

Water is sent to anion filter form decarbonized water tank, using pumps. There are four filters in which one is used and other are for backup. Each filter has capacity of 90T/h. NaOH is introduced in water to remove silica and other anions. As we can see the equation.

SiO2 + 2 NaOH→ Na2SiO3 + H2O.

3.3.5. Cation Filter # 2.

If any amount of cations remain in water even after cation filter, these filters remove those cations. 98% pure H2SO4 is added in this filter to provide more H+ ions.

3.3.6. Mixed Bed Filter.

This is the last stage of water treatment procedure. It has the capability to remove both cations and anions from water. They have a very good efficiency. This filter can operate for 3 to 4 hours if cation or anion filter do not work. In this filter water is passed through sulfuric acid and sodium hydro-oxide to remove the remaining cations and anions in the water.

3.3.7. Dematerialized Water Tank

After passing through the filters, water is sent to the demi water storage tank. This water has no hardness and all other minerals values in tolerable ranges. Three tanks are available, each with the capacity to store 2000 metric ton water. This water is supplied through pumps to the makeup connection after hot well to fulfill the demand of unit.


Chapter 4:

POWER PLANT FUEL

4.1. Fuel Oil Facilities.

Fuel is provided to the power plant by two major sources which are1- Oil Tankers2- Train he block diagram of oil feeding system to power plant is given below.

Most of the furnace oil of power plant is provided by the oil tankers.

4.2. Oil Feeding System.

The block diagram of oil feeding system to power plant is given below.

4.2.1. Decanting

The place where the oil is obtained from the oil tankers and trains is known as oil decanting.It is like a deep pit under earth where fuel oil facilities discharge their oil.

4.2.2. Transfer Pumps.

Transfer pumps used to take oil from decanting pit and transfer it to the main oil storage tank.There are four transfer pumps by which 3 are functional and 1 is for backup.

4.2.3. Storage Tanks.


There are 6 oil storage tanks are installed in the plant for phase-I, each has 20,000m3 capacity. To enhance the efficiency of the plant, small amount of MgO is added as a catalyst in the oil which improves combustion process.

4.2.4. Recirculation pumps.

Recirculation pumps are used to keep oil in warm conditions the take oil from storage tanks and pass it from heater and then again feed it back to the storage tank.

4.2.5. Recirculation heaters.

Recirculation heaters are used to keep storage tank’s oil in warm condition. In short they increase the oil efficiency because; combustion of warm oil becomes very easy. Their temperature is above 80C.

4.2.6. 1st Lift Pump.

1st lift pump is used to take oil from storge tank and passes it through the main steam heater and it also provide the suction to the 2nd lift pump. There are four 1st lift pumps are used and their discharge pressure is about 7-8kgN/cm^2.

4.2.7. Main Heater.

Main heaters are used to warm the oil for combustion process. They use steam for heating purpose. Here the temperature of oil rises to 110C which is necessary for combustion because, if the temperature of furnace oil below 100C then it can’t combust properly.

4.2.8. 2nd lift Pump.

2nd lift pump is used to take warm oil from main heaters and transfer it to the boiler side.There are 4 2nd lift pumps are used and their discharge pressure is about 40-45kgN/cm^2.

4.3. Diesel oil Tanks.

There are two diesel oil tanks at phase # 1. Each has a capacity to store 1000T diesel oil.Power plant uses diesel oil for few hours at the starting time.


4.4. Fuel Requirements.Fuel requirements for the power plant are given in the table below.

Unit No. FO requirement/ day (MT) NG requirement/ day (MMSCFD)

1,2 & 3 3600 114

4 1800 50-70

5 & 6 2400 76


Chapter 5:

ELECTRICITY GENERATION.

5.1. Main Generators.

Generator is a machine which converts mechanical energy into electrical energy. It has a moving part called rotor and a stationary part called stator. A generator has two types of windings

1- Field winding2- Armature winding.

In this power plant turbo generators are used because of single shaft of turbine and generator. Main generator is a three phase two pole synchronous generator its specifications are given below.

Sr. No. Generator’s Parameters Values

1 Part no. TBB – 220 – 2E

2 Active Power 210MW

3 Reactive power 133MVAr

4 Apparent Power 247MVA

5 Power Factor 0.85

6 Frequency 50Hz

7 RPM 3000

8 Stator Voltage 15.75kV

9 Stator Current (Rated) 9056A

10 Rotor Voltage 303V (D.C)

11 Rotor Current (Rated) 2330A (D.C)

12 No. of Poles 2

5.1.1. Generator’s Cooling System.

There is a proper cooling system for the generator winding. Its stator winding is cooled by the distillate water and rotor winding is cooled by the pure hydrogen gas.The quality of distillate water is maintained by chemical lab testing and its resistance is maintained to above 200 (kilo-ohm/cm) so that it can’t conduct between the stator windings.Its flow rate inside the generator is about 30T/h, which is accomplished by 2 pumps (1 operational and other standby) and their discharge pressure is about 6.5kgN/cm^2.


For rotor cooling hydrogen gas is used because its flow rate is higher than water and it has a unique property of rapid cooling than water. Its pressure is maintained to 4kgN/cm^2 and its oil is used for its sealing which has a pressure of 4.7kgN/cm^2.

5.1.2. Generator Protection System.

There is a protection system for the generator to prevent it from any kind of damage in case of any kind of fault occur. Generally there are three major faults occur which are:

1- Stator Faults2- Rotor/Excitation Faults.3- System Faults.

These protections are given below.

A. Stator Faults:

i. Phase short circuit protection:

In case of short-circuits between phases in the stator winding or between the generator terminals, the machine must quickly be disconnected from the network and brought to a complete shutdown in order to limit the damage.Differential relays are used for this purpose. Longitudinal differential protection is used which means rapid and selective relay protection of feeder and interconnectors based on a direct comparison of the currents at the end point of cables.

ii. Earth fault Protection:

Common practice is to earth the generator neutral through a resistor, which gives a maximum earth-fault current of 5-10 A. Short-circuits between the stator winding in the slots and the stator core are the most common electrical fault in generators. The fault is normally initiated by mechanical or thermal damage to the insulating material or the anti- corona paint on a stator coil. Inter-turn faults, which normally are difficult to detect, will quickly develop into an earth-fault and will be tripped by the stator earth-fault protection.

iii. Phase inter-turn fault protection:

Inter-turn faults can only occur in case of double earth-faults or as a result of severe mechanical damage on the stator end winding. Due tothe difficulties in obtaining a reliable and secure inter-turn protection, it is in most cases omitted. It is assumed that the inter-turn fault, first of all, will lead to a single phase earth fault at the faulty spot, and the machine will then be tripped by the earth-fault relay within 0.3 – 0.4 s.

iv. Thermal overload protection:

Overloads up to 1.4 times the rated current are not normally detected by the impedance or over current protection. Sustained overloads within this range are usually supervised by temperature monitors (resistance elements) embedded at various points in the stator slots.


B. Rotor/Excitation faults:

i. Loss of excitation protection:

A complete loss-of-excitation may occur as a result of:• Unintentional opening of the field breaker• An open circuit or a short circuit of the main field• A fault in the automatic voltage regulator (AVR), with the result that the field current is reduced to zero.When a generator with sufficient active load loose the field current, it goes out of synchronism and starts to run asynchronously at a speed higher than the system, absorbing reactive power (VAR) for its excitation from the system.

ii. Rotor earth fault Protection:

The rotor circuit can be exposed to abnormal mechanicalor thermal stresses due to vibrations, excessive currents or choked cooling medium flow etc. This may result in a breakdown of the insulation between the field winding and the rotor iron at one point where the stress has been too high. The field circuit is normally kept insulated from earth. A single earth-fault in the field winding or its associated circuits, therefore, gives rise to a negligible fault current and does not represent any immediate danger. If, however, a second earth-fault occurs, heavy fault current and severe mechanical unbalance may quickly arise and lead to serious damage. It is essential, therefore, that any occurrence of insulation failure is discovered and that the machine is taken out of service as soon as possible. Normally, the machine is tripped after a short time delay.

iii. Bearing insulation/ shaft current protection:

Emf is developed in the shaft of the generators due to the magnetic dissimilarities in the armature field. The emf normally contains a large amount of harmonics. If the bearing pedestals at each side of the generator are earthed the induced emf will be impressed across the thin oil-films of the bearings. A breakdown of the oil-film insulation in the two bearings can give rise to heavy bearing currents due to the very small resistance of the shaft and the external circuit. Consequently, the bearing base farthest from the prime mover is usually insulated from earth and the insulation supervised by a suitable relay. To prevent the rotor and the shaft from being electro-statically charged, the shaft of turbo-generators is usually grounded via a slip-ring on the prime mover side.

C. System Faults:

i. Stator over load protection:

When load currents exceed the rated values there is a future risk that conductors and insulation will be damaged due to overheating. To avoid this damage, stator over load protection is kept in mind.24


ii. Reverse power protection:

Its basic purpose is to protect prime mover. If the driving torque becomes less than the total losses in the generator and the prime mover, the generator starts to work as a synchronous compensator, taking the necessary active power from the network. In case of steam turbines, a reduction of the steam flow reduces the cooling effect on the turbine blades and overheating may occur.

iii. Unbalance load/ negative sequence current protection:

The negative-sequence current produces an additional ampere-turn wave which rotates backwards, hence it moves relatively to the rotor at twice the synchronous speed. The double frequency, eddy currents induced in the rotor may cause excessive heating, primarily in the surface of cylindrical rotors and in the damper winding of rotors with relevant poles.

iv. Accidental stator energizing/Dead machine protection:

Three-phase energization of a generator which is at standstill or on turning gear causes it to behave and accelerateSimilarly, to an induction motor and high currents develop in the rotor during the period it is accelerating. Although the rotor may be thermally damaged from excessive high currents, the time to damage will be on the order of a few seconds. However, of more critical concern is the bearing, which can be damaged in a fraction of a second due to low oil pressure. Therefore, it is essential that high speed clearing be provided. For the offset mho type of loss-of-excitation relay, operation is marginal when setting and relay tolerances are considered, and the operate time would, in any case, be in the order of hundreds of milliseconds. The back-up impedance relay and the reverse power relay would operate with a typical time delay of 1-2 or 10-20s respectively. For big and important machines, fast protection against inadvertent energization should be included in the protective scheme.

v. Under frequency protection:

In practice, prolonged generator operation at low frequency can only occur when a machine with its local load is separated from the rest of the network. The necessity of under-frequency protection has to be evaluated from knowledge of the network and the characteristics of the turbine regulator.

vi. Over frequency protection:

Steam turbines are also sensitive to over-speed. For large steam turbine generators, over-frequency protection with one or two frequency stages should be included. The protection will provide a back-up function for the speed monitoring device.

vii. Over voltage protection:


If circuit breaker of the generator trips when it is working at its full load and rated power factor a subsequent increase in terminal voltage is occurs which is controlled by AVR. However, if AVR is faulty the severe over voltage conditions will be reached. With this rise in voltage a simultaneous over-speeding should occur. An instantaneous high set voltage relay can be included to trip the generator quickly in case of excessive over-voltages following a sudden loss of load and generator over-speeding.

viii. Under voltage protection:

Generally, the rating of one machine is small in comparison with an interconnected system. It is, therefore, not possible for one machine to cause an appreciable rise in the terminal voltage as long as it is connected to the system. Increasing the field excitation, for example owing to a fault in the AVR, merely increases the reactive Mvar output, which may, ultimately, lead to tripping of the machine by the impedance relay or the V/Hz relay. In some cases, e.g. with peak-load generators and synchronous condensers, which are often called upon to work at their maximum capability, a maximum excitation limiter is often installed. This prevents the rotor field current and the reactive output power from exceeding the design limits.25

ix. Over excitation protection:

The excitation flux in the core of the generator and connected power transformers is directly proportional to the ratio of voltage to frequency (V/Hz) on the terminals of the equipment. The losses due to eddy currents and hysteresis cause the temperature rise, increasing proportion to the level of excitation. The core laminations can withstand relatively high over fluxing without becoming excessively heated, but unlamented metallic parts can experience severe heating in a short time. The risk of over excitation is, obviously, largest during periods when the frequency is below rated value. The proper way of protection is to use a relay which measures the ratio between voltage and current (V/Hz) relay.

x. Out-of-step operation/ loss of synchronism protection:

Loss of synchronism may be harmful to a rotating machine if not detected already after a few pole slips and the machine is disconnected from the network. Detection may be by counting over-current pulses or by watching the load apparent impedance. The impedance locus would typically perform circles in the impedance plane, from low impedance (180 degrees out-of-step) to high impedance.

5.2. Excitation Control System.

In the power houses main generators are excited by the outer supply, so that their output voltages can be controlled according to the system demands. In this power plant there is a vast excitation control system. Its diagram is given on the next page.

According to the excitation diagram there is a main exciter for the main generator’s excitation the basic principle of the excitation is that in the starting of generator its exciter takes DC Battery’s supply for the rotor field then the exciter’s stator voltages converted into DC by


passing through thyrestors and then DC battery supply disconnected and DC supply from the thyrestors connected, in this way the exciter is self excited through its own stator supply.After that the stator voltage of main exciter given to the main thyrestors to convert them into DC and those DC voltages are provided to the main generator’s rotor field. Hence the Main generator is excited by the main exciter and the out voltages about 15.75kV are taken from the stator. The description of previous diagram is given below.

5.2.1. Main Exciter.

For each Main generator there is a main Exciter for its excitation. It provides DC to the rotor of the generator to produce electromagnet. Exciter itself is an AC generator. Its output is transfer to the thyristor converters. They convert AC into DC and send it to the rotor of generator. Rotor of exciter also required DC. This DC is provided by batteries for 3 seconds and later DC comes from thyristor converters. Rotors of generator and exciter are rotates on the same shaft, rotated by turbines. Unit # 1, 2 & 3 has exciters with specifications:

1- Active Power = 1010 kW, 2- P.F. = 0.46, 3- Speed = 3000RPM, 4- f = 50Hz, 5- Vstator=520V,6- Istator=2400A,7- Irotor=154A.

5.2.2. Thyristors.

Thyristor is the semi-conductor device used to convert AC Power into DC Power. They are also used to regulating AC voltages by cutting the AC waveform shape by different angles.

5.2.3. CT’s & PT’s.

CT (Current Transformer) and PT (Potential Transformer) are the instrumentation transformers which are used to measure the current and voltage respectively.

5.2.4. AEC or AVR.

AEC (Automatic Excitation control) is a device which measures the system voltages and compares them with the output voltages of generator and then adjust the excitation voltages of generator so that the generator’s voltages and system voltages can be synchronized.It is also called the AVR (Automatic Voltage regulator).

5.2.5. Manual Control System.


In case of any fault if the AEC or AVR stop working then there is a manual control system to adjust the generator’s output according to the system voltages. The manual control system is quit difficult to use.

5.3. Main Transformers.

A transformer is a static machine/device that transforms an alternating current (AC) input voltage into a higher or lower AC output voltage. Transformers are not designed to raise or lower direct current (DC) voltages. A LPT (Large Power Transformer) is a large, custom-built piece of equipment that is a critical component of the bulk transmission grid. Its diagram is given below.

Figure illustrates a standard core-type LPT. Although LPTs come in a wide variety of sizes and configurations, they consist of two main active parts:

1- The core, which is made of high permeability, grain-oriented, silicon electrical steel, layered in pieces.

2- Windings, which are made of copper conductors wound around the core, providing electrical input and output.


5.3.1. Transformer Winding.

In this power plant main transformer is an auto transformer with tap changers. Its winding diagram is given below.

These are three phase star connection transformers with tertiary winding in delta cconnection.The tertiary winding is for the safety of transformer in case of line fault occur.

5.3.2. Transformer Cooling System.

The cooling of these transformers is done by the oil cooling system. These transformers use the OFAF (Oil Forced Air Forced) principle for the cooling in which oil is forced by the pumps to circulate between the windings.

5.3.3. Transformer Protections.

Some major transformer protections are given below.

A. PERCENTAGE DIFFERENTIAL PROTECTION

This scheme is employed for the protection of transformers against internal short circuits. It provides the best overall protection for internal faults. However in case of ungrounded or high impedance grounding it cannot provide ground fault protection.The following factors affect the differential current in transformers and should be considered while applying differential protection.

1. Magnetizing inrush current

The normal magnetizing current drawn is 2–5% of the rated current. However during Magnetizing inrush the current can be as high as 8–30 times the rated current for typically 10 cycles, depending upon the transformer and system resistance.


2. Over excitation

This is normally of concern in generator–transformer units. Transformers are typically designed to operate just below the flux saturation level. Any further increase from the max permissible voltage level (or Voltage/Frequency ratio), could lead to saturation of the core, in turn leading to substantial increase in the excitation current drawn by the transformer.

B. RESTRICTED EARTH FAULT PROTECTION

A percentage differential relay has a certain minimum value of pick up for internal faults. Faults with current below this value are not detected by the relay.Winding-to-core faults, which are single phase to ground type, involving high resistance, fall in this category. Therefore for such type of faults RESTRICTED EARTH FAULT PROTECTION is used. The reach of such a protection must be restricted to the winding of the transformer; otherwise it may operate for any ground fault, anywhere in the system, beyond the transformer, hence the name of this scheme.

C. OVER CURRENT PROTECTION

Over current protection is used for the purpose of providing back up protection for large transformers. (above 5MVA).Two phase fault and one ground fault relay is sufficient to provide OC protection to star delta transformer.

D. PROTECTION AGAINST OVERHEATING

The rating of a transformer depends on the temperature rise above an assumed maximum ambient temperature. Sustained overload is not allowed if the ambient temperature is equal to the assumed ambient temperature. The maximum safe overloading is that which does not overheat the winding. The maximum allowed temperature is about 95°C. Thus the protection against overload depends on the winding temperature which is usually measured by thermal image technique.

E. PROTECTION AGAINST INCIPIENT FAULTS

Faults which are not serious at the beginning but which slowly develops into serious faults are known as incipient faults.

BUCHHOLZ RELAY:


It is a gas actuated relay. When a fault develops slowly, it produces heat, thereby decomposing solid or liquid insulating material in the transformer. The decomposition of the insulating material produces inflammable gases. The Buchholz relay gives an alarm when a specified amount of gas is formed. The analysis of the gas collected in the relay chamber indicates the type of the incipient fault.

F. PROTECTION AGAINST FIRE

Power transformers are subject to fires from many sources. They often occur because of deterioration of insulation in the transformer. This produces arcing which in turn overheats the insulating oil and causes the tanks to rupture; further arcing then will start a fire. Fires are also initiated by lightning and occasionally by dirty insulators on the outside of the tanks.There is a fire fighting system developed around these transformers to save the transformers for further damage. Its diagram is given below.

G. PROTECTION AGAINST LIGHTNING

Lightning overvoltage surges originate from atmospheric discharges and they can reach their peak within a few microseconds and subsequently decay very rapidly. The surge voltage can reach up to 10 times the rated transformer voltage and they pose the greatest threat to transformers on the distribution networks. The charge from the surge produces both short duration high current impulse and long duration continuing current impulse which affects the transformer insulation system.Protection against such overvoltage surges can be achieved by using Lightning Arresters. The distance between the lightning (surge) arrester and the equipment to be protected should be as short and straight as possible.

5.4. Auxiliary Transformers.


Auxiliary transformer is used to produce supply to the auxiliary equipment of power plant.In this plant three types of auxiliary equipments which are

1- 6.6 kV Auxiliary Equipments2- 400 V Auxiliary Equipments3- 220 V Auxiliary Equipments

The diagram of main auxiliary transformer is given below.

This is a step down (15.75kV/6.6kV) auxiliary transformer. In this power plant there is an auxiliary transformer between the two units and it takes supply from one unit at a time. If one of these two units is powered off then the connection of auxiliary transformer is shifted to other unit. Similarly there is another standby step down (220kV/6.6kV) auxiliary transformer which becomes operational when both of the units tripped or powered off. It takes supply from the system and step down it for auxiliary system.


5.5. Main Auxiliary Equipments

Some main auxiliary equipment and their specifications are given in the table below.

Sr. No. Equipment Name Total Quantity Quantity Per

Unit Power Ratings

1 Condensate Cycle Pump 9 2 6.6kV, 2MW

2 Feed Water Pumps 9 2 6.6kV, 3.5MW

3 Force Draft Fans 6 2 6.6kV, 1000kW

4 Induced Draft Fans 6 2 6.6kV, 1250kW

5 GRC Fans 6 2 6.6kV, 2A

6 Circulate Water Pump 8 2 6.6kV

7 Makeup Pumps 5 --- 6.6kV.

8 Recirculation Pumps 2 --- 0.4kV

9 1st lift Pumps 4 --- 0.4kV, 270A

10 2nd lift Pumps 4 --- 6.6kV, 25.2A

11 Cooling Tower Fans 48 16 0.4kV, 200A

12 Turning Gear Motor 3 1 0.4kV.

13 Transfer Pumps 4 ---- 0.4kV

14 Turbine Oil Pumps 6 2 0.4kV

5.6. Auxiliary Control System.

For the control and protection of auxiliary equipments there are some auxiliary switchgear rooms in the power plant. As we can see the auxiliary power panels in the figure below


6. Chapter 6:

220kV SWITCHYARD

6.1. Busbar System.

A busbaris a strip or bar of copper, brass or aluminum that conducts electricity within a switchboard, distribution board, substation, battery bank or other electrical apparatus. Its main purpose is to conduct electricity. The cross-sectional size of the busbar determines the maximum amount of current that can be safely carried.

6.1.1. Busbar Schemes.

There are five main busbar schemes used in the switchyard these are given below.1- Single Busbar Scheme.2- Double Busbar Scheme.3- Double Busbar with single breaker Scheme.4- Double Busbar with one and half Scheme.5- Ring Busbar scheme.

In this plant a double busbar with single breaker scheme is used and also there is a transfer busbar used in case of bypass the faulty area and to avoid supply interruption.The busbar scheme diagram of this power plant is given below.


http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Battery_(electrical)

http://en.wikipedia.org/wiki/Electrical_substation

http://en.wikipedia.org/wiki/Distribution_board

http://en.wikipedia.org/wiki/Electric_switchboard

http://en.wikipedia.org/wiki/Electricity

http://en.wikipedia.org/wiki/Aluminium

http://en.wikipedia.org/wiki/Brass

http://en.wikipedia.org/wiki/Copper

6.2. Isolators

Isolator is a manually operated mechanical switch which separates a part of the electrical power system normally at off load condition. It is also called a disconnect or. It has three types:

1- Double Break Isolator.2- Single Break Isolator.3- Pantograph type Isolator.

In this yard a single break isolator is used. Its diagram is shown below.


6.3. Circuit Breakers.

Electrical circuit breaker is a switching device which can be operated manually as well as automatically for controlling and protection of electrical power system respectively. As the modern power system deals with huge currents, the spacial attention should be given during designing of circuit breaker to safe interruption of arc produced during the operation of circuit breaker. The modern power system deals with huge power network and huge numbers of associated electrical equipment. During short circuit fault or any other types of electrical fault these equipment as well as the power network suffer a high stress of fault current in them which may damage the equipments and networks permanently. For saving these equipments from damage the circuit breakers are used.

6.3.1. Air Blast Breakers.

These types of air circuit breaker were used for the system voltage of 245KV, 420KV and even more, especially where faster breaker operation was required. Its internal diagram is given on next page.


Air blast circuit breaker has some specific advantages over oil circuit breaker which are listed as follows,

1- There is no chance of fire hazard caused by oil.2- The breaking speed of circuit breaker is much higher during operation of air blast

circuit breaker.3- Arc quenching is much faster during operation of air blast circuit breaker.4- The duration of arc is same for all values of small as well as high currents

interruptions.5- The stability of the system can be well maintained as it depends on the speed of

operation of circuit breaker.6- Requires much less maintenance compared to oil circuit breaker

6.3.2. SF6 Breakers.

A circuit breaker in which the current carrying contacts operate in sulphur hexafluoride or SF6 gas is known as an SF6 circuit breaker.SF6 has excellent insulating property. SF6 has high electro-negativity. That means it has high affinity of absorbing free electron. Whenever a free electron collides with the SF6 gas molecule, it is absorbed by that gas molecule and forms a negative ion. As we can see the equation


http://www.electrical4u.com/sulfur-hexafluoride-sf6-gas-properties/


http://www.electrical4u.com/electrical-switchgear/oil-circuit-breaker.php

http://www.electrical4u.com/arc-interruption-theory/

http://www.electrical4u.com/oil-circuit-breaker-bulk-and-minimum-oil-circuit-breaker/

SF6 + e = SF6 –

These negative ions obviously much heavier than a free electron and therefore over all mobility of the charged particle in the SF6 gas is much less as compared other common gases. We know that mobility of charged particle is majorly responsible for conducting current through a gas.Hence, for heavier and less mobile charged particles in SF6 gas, it acquires very high dielectric strength. Not only the gas has a good dielectric strength but also it has the unique property of fast recombination after the source energizing the spark is removed.

There are mainly three types of SF6 CB depending upon the voltage level of application1- Single interrupter SF6 CB applied for up to 245KV(220KV) system2- Two interrupter SF6 CB applied for up to 420KV(400KV) system3- Four interrupter SF6 CB applied for up to 800KV(715KV) system

In This yard single interrupter SF6 CB is used because, it’s a 220kV yard.

6.4. PT (Potential Transformer).

Potential transformer is a simple step down transformer used for instrumentation purpose in the switchyard. It works on the principle of mutual induction. Its winding diagram is given below.



6.5. CT (Current Transformer)

Current transformer is also used for the instrumentation purpose in the switch yard. It gives the voltage with respect to current passes through the conductor its winding diagram is given belod.

It has only single winding. It works on the principle of clamp meter in which when current passes through the conductor the amagnetic field is developed around it, that field induced into the single winding of CT and it gives the output voltages.


6.6. Surge Arrestors.

Surge arrestors are simply the lightning arrestors used for the protection of system against lightning fault. Its diagram is given below.


6.7. Control System.There is a control room of switchyard in which we control the all equipments of switchyard by remote buttons. For example turning on or off the CB manually, open or closed the isolator etc.


SWOT ANALYSES


STRENGTHS The largest Generation Company in Public Sector.

Provision of Dual Fuel Firing

Power Plants are located in the load centers.

Availability of land for capital expansion.

Road and Rail facilities for furnace oil supply.

Highly qualified skilled labor available.

Established infrastructure.

Experienced & dedicated engineers available.

Correction of the bills

Co-location of XEN & RO offices

Good relation with different departments

Restructure of stores to ensure prompt availability

Printing a last 12 month history on bill

Provide full facility to customer for paying bill

Central chief executive customer service center

Provide a computerized service center to each circle

Mobile customer service facility

Establish a marketing cell

Provide high technology for development and maintenance


WEAKNESSES

Heat rate is high as compared with the design value due to deterioration of

the plant.

Lack of capital investment.

Drain out of skilled manpower to IPPs/abroad and Rental Power Plants due

to low salaries as compared to private sectors.

Ineffective preventive maintenance due to non-availability of spare parts and

delay approvals of shutdown of the units.

Ineffective performance appraisal system.

Delayed decision making.

Ineffective material management system.

Non availability of GAS.

They take so much time for processing any project.

Lack of communication level between employees.

Most of department based on manual system.

Lack of loyalty in front of customer.

Administrative cost of the company is very high due to which the

profitability of the company decreases.

There is still improvement of technology in the genco computers.

There is no objective / target for employees

Performance of service center is not too great for satisfaction to customer

People has less trust over company

Dealing to customer not too much efficient


OPPORTUNITIES

Use of land for expansion.

Vicinity of Furnace Oil Refinery.

Modification / Rehabilitation of Plant in process.

Expansion in installed capacity.

Goals of corporation and commercialization plan at one time.

Provide a facility of mobile customer services center at each circle.

For reduction in energy loses used the distribution system rehabilitation

under system augmentation program (SAP).

It should be on time development works an LT/HT proposals under SAP.

Establish a new grid station.

Extension of existing grid station.

Transmission lines.

Conversion of our all transportation to CNG.

Provide a facility of new vehicles for field and operation sector employees.

No competitor in local market so it can increase shares

Services easily in market


THREATS

Influence of Oil Mafia.

Lack of Fuel/Gas Supply.

Security lapses.

Dishonesty of officials.

Low government budget.

Not a good support for supplier.

Heavy taxes by government.

Daily differ fluctuation of supply is the permanent treat.

Day by day technology change.

Overall performance is decreasing.

Some government project spoilage the GENCO image.

Politic in employees

Labor unions are very awful for company.

In future market value will be decreases.

Political environment are decreasing the efficiency of the company.

RECOMMENDATIONS(Genco-III) Northern Power Generation Company Limited

70 | P a g e

The trust of the customer must be retained.

The employees must be well trained for customer services issues.

Attendance system of the employees must be changed.

Give full safety to the employees.

Communication gap between upper level and lower level employees must be

improved.

The procedure of new connection meter must be reduced staff.

The organization hierarchy must be reduced in the organization.

Give more concentration for the low level employees.

Must give the safety precaution to the employees.

Take some steps for create understanding between different departments.

To increase their productivity.

The top management should give authority to the managers to take decision

according to the situation at any time and in the absence of top management.

Appoint skillful and talented people to increase the productivity and utility of

company.

Arrange different seminars and conferences for employees.

All the duties and responsibilities of each employee should be clear.

Try to more use of latest technology in offices.

There should be decentralization of decision making.

Management should be recruit right person for right job

Behavior with customer should be improved.

Make better plan for stop the line loses.

Offer new training course to the employees.

The management should have multi skilled so achieve at economy of scale.

Pay procedure should be clear and at a time.

Provide friendly working environment.

CONCLUSION


I chose the (Genco-III) Northern Power Generation Company Limited for my

internship training, which is necessary for my 4 year Bs Electrical Engineering

&Technology degree. I worked in head office of (Genco-III) Northern Power

Generation Company Limited for four (4) months in different departments During

my internship I worked in these departments under the supervisions of concerned

different Engineers. The staff at (Genco-III) Northern Power Generation Company

Limited is very corporative and supportive. I try to give best and careful analyzed all

the department of the company. I take information of these departments. Although

the four month training duration is short period for study of an Electricity Generation

plant, but I learned a lot due to the help of the Engineers. I worked in different

departments of the Plant during my internship training.

At last I put SWOT analysis of Genco Company that I realized there and put

recommendation that will be beneficially for company.


Finaly TPS report

Documents