PRIME UNIVERSITY

Ghorashal 950MW Thermal Power Station

Name of Report: Study Tour of Power System Protection Lab

& Power System Lab.

Place of Study Tour: Ghorashal 950MW Thermal Power Station.

Submitted To: Fahim Rashid, Lecturer,

Department of EEE,

Prime University

Submitted by: Name: Faisal Ahamed

ID : 102030301072

Batch : 24th

Dept. : EEE

ABOUT GHORASAL POWER STATION

Ghorashal 950MW Thermal Power Station

INTRODUCTION:

Different types of power plants generate electricity and synchronize it with the

national grid. There are some isolated diesel power stations at remote places and

islands which are not connected with the National Grid.Terminal voltage of

different generators are 11 KV, 11.5 KV and 15.75 KV.In the Eastern Zone

(eastern side of river Jamuna), electricity is generated from indigenous gas and a

small percentage through hydro power. In the Western Zone, Coal and imported

liquid fuel is used for generation of electricity. The fuel cost per unit generation in

the Western Zone is much higher than that of the Eastern Zone. Therefore, as a

policy, low cost electricity generated in the Eastern Zone is transferred to the

Western Zone through the 230 kV East-West Inter connector transmission line.It

may be mentioned that the Ghorashal Power Station is the largest power station in

Bangladesh and started its operation in the year 1974.The Department of Electrical

& Electronic Engineering (EEE) undertook a study tour to Ghorashal 950MW

Thermal Power Station, Polash, Narshingdi (the biggest power plant of

Bangladesh) on 7th of November, 2013. Study tour to observe the electricity

generation & transmission and power station operation & maintenance are relevant

and enrichment activities of the electrical engineering education.

Ghorashal Power Station having installed capacity of 950 MW is the biggest

power station in Bangladesh.

It has 6 units of gas fired stream turbine power plant.

Installed capacity of unit # 1& 2 is 55 MW each.

Installed capacity of unit # 3to 6 is 210 MW each.

Philosophy of generation

Stream produced in boiler

Stream forced to rotate turbine & rotational

Energy transformed in to electrical energy in to the generator.

Steam power plant energy conversion

Chemical energy of

fuel

Converted to heat energy

in Boiler

Heat energy converted to Mechanical energy in Turbine

Mechanical energy

converted to Electrical energy in generator

Fig: Power flow diagram

SYSTEM OF 55 MW UNIT

Boiler: Type-T.M-157

Steam generating capacity 230 Ton/hr

Steam pressure at boiler out let 100 kg/cm

Rated live steam temperature 540

Efficiency 90.5%

Flue gas temperature 120

Steam boiler is drum type with two stage evaporation system

It has steam separating cyclone

It is equipped with burners using natural gas

It is gas tight with balanced draft

It has two separate flows passing along steam and water ducts

Turbine:

Type-k-55-90-4

Nominal speed -3000 RPM

Live steam pressure -90kg/cm

Steam flow at rated /Full load 216Ton/hr

Live steam temperature 535

NO of bleed off points-7

Generator:

Type TB -60-2

Manufacturer “Electrosila” ,Russia

Nominal rating(Mw) 55

Terminal voltage(kv) 10.5

Stator current/rated (Amp) 3780

Rotor voltage /rated(v) 400

Rotor current/rated(Amp) 1445

Power factor .8

frequency 50

Nominal speed(RPM) 3000

Cooling system Hydrogen cooling

The turbine Generator utilizes the static self-excitation system with booster

transformer.

The Generator uses strong automatic excitation regulation.

The stand by excitation is an electric machine excitation.

SYSTEM OF 210 MW UNIT

Boiler:

Steam boiler is a drum type with two-stage evaporation system.

It has steam separating cyclone.

It is equipped with burner using natural gas.

It is gas tight with balanced draft.

It has two separate flows passing along steam and water ducts.

Picture of Boiler

Type TGME-206/COB

Steam generating

capacity(Ton/hr)

670

Steam pressure at boiler out

let(kg/cm)

140

Rated live steam temperature( C) 540

Secondary steam temperature( C) 540

Efficiency (in %) 93

Flue gas temperature( C) 132

Turbine:

Type k-210-130-3

Nominal speed,RPM 3000

Steam flow at rated/full load(ton/hr) 636

Live steam pressure(kgf/cm) 130

Live steam temperature( C) 540

Secondary steam temperature( C) 540

Steam condensate turbine is a single shaft t three cylinder set with intermediate

It is designed for direct rotation of A.C generator.

GENERATOR CONSTRUCTION DETAILS (210 MW)

Picture of Generator

Generator:

Type TGB-200MT3

Nominal rating(MW) 210

Terminal voltage(kv) 15.75

Stator current/rated(amp) 9060

Rotor voltage/rated(v) 430

Rotor current/rated(amp) 1950

Power factor .85

frequency 50

Nominal speed(RPM) 3000

Cooling system Hydrogen and water cooling

The turbo generator utilizes the static self-excitation system with booster

transformer.

The generator uses strong automatic excitation regulation.

The stand by excitation is an electric machine excitation.

About Generator: An electrical generator is a machine, which converts

mechanical energy (or power) into electrical energy (or power). Energy conversion

is based on the principal of the production of dynamically (or motionally) induced

emf. Whenever conductor cuts magnetic flux, dynamically induced emf is produced

in it according to Faraday’s Laws of electromagnetic induction. This emf causes a

current to flow if the conductor circuit is closed. Hence two basic essential parts of

an electrical generator are 1) A Magnetic field & 2)A Conductor or Conductors

(armature) which can so move as to cut the flux. Generators are A.C. or D.C. the

device in which electricity is generated by keeping the magnetic field stationary and

armature rotating is called D.C. generator and the device in which electricity is

generated by keeping the armature (conductor) stationary and magnetic field

rotating is called A.C. generator. In the case of A.C. generators standard

construction consists of armature winding mounted on stationary element called

stator and field windings on a rotating element called rotor. The details of

construction are as elaborated ahead.1)Stator : consists of Body/Frame, Core,

Winding, Distillate Header, Terminal Bushing, End shield, gas coolers etc.2)Rotor :

consists of shaft, winding, wedges, retaining ring, fans, field leads, slip ring &bush

gear.

STATOR:

The stator body with core and stator winding form the heaviest component of the

entire Turbo generator. The active parts to be accommodated and the forces and

torque arising during operation call for a rigid and strong stator shell. Moreover, it

is designed tow ithstand high internal pressure, which may arise due to unlikely

event of explosion of hydrogen air mixture without any residual deformations.

Stator body is a totally enclosed gas tight fabricated structure made up of high

quality mild steel and austenitic steel. It is suitably ribbed with annular rings called

inner walls to ensure high rigidity and strength. The arrangement, location and

shape of inner walls is determined by the cooling circuit for the flow of gas and the

required mechanical strength and stiffness and side walls are suitably blanked to

house four longitudinal hydrogen gas coolers in-side the stator body.

Fig: Stator of Generator in Ghorasal Power Station

STATOR WINDING:

The stator has a three phase, double layer, short pitched and bar type of winding

shaving two parallel paths. Each slot accommodates two bars. The slot lower bars

and the slotupper bars are displaced from each other by one winding pitch and

connected at their ends so as to form coil groups.

LAYING OF STATOR WINDING:

The stator winding is placed in open rectangular slots of the stator core which are

uniformly distributed on the circumference. After laying top bar, slot wedges are

inserted. Below slot wedges, high strength glass textolite spacers are put to have

proper tightness. In between top and bottom bars, spacers are also put. These

measures prevent vibrations that may be set up by the bar currents.

ROTOR:

The rotor comprises of following components

1.Rotor shaft

2.Rotor winding

3.Rotor wedges & other locating parts for winding

4.Retaining ring

5.Fans

6.Field lead connections

Fig: Rotor of Generator in Ghorasal Power Station

DISCUSSION ABOUT TOUR:

Picture of Ghorashal 950MW Thermal Power Station

The Department of Electrical & Electronic Engineering (EEE) undertook a

study tour to Ghorashal 950MW Thermal Power Station, Polash, Narshingdi (the

biggest power plant of Bangladesh) on 7th

of November, 2013. Study tour to

observe the electricity generation & transmission and power station operation &

maintenance are relevant and enrichment activities of the electrical engineering

education. This time the tour was organized for the students of Power System

Protection Lab course and arranged by the course coordinator Fahim Rashid,

Lecturer of EEE Department With Saikat Basak Lecturer of EEE Department and

Indraneel Misra, Jr. Lecturer & Asst. proctor in order to introduce the students

with the power station operation and maintenance concepts with accompanied 45

enthusiastic students in the tour.

One of a group from the Tour with Teachers

On arrival, teachers and students were greeted by the engineers and officials of

Ghorashal Power Station. Students were then divided into four groups and were

given introductory speech about the power station by four plant engineers. They

were demonstrated about the working principle of thermal power station,

description of the cycle, working function of primary and auxiliary equipments etc.

The four groups of students were then taken to visit the 6 (six) generator-turbine

units and the related control center of the power station. They were demonstrated

about the working principles of turbine, generator, governor, cooling system,

boiler, economizer, super heater, reheater, sub-station, protection devices,

switchgear facilities etc. of this 950MW power station.

One group with Engr. Kshirod Mohan Bose

Sub- Divisinal Engineer (Boiler)

5-6 Unit, Ghorashal Power Station

The students got a practical idea about the working principle of a thermal power

station. It was a good learning experience for them to see the actual management

operations too. The Department of EEE extends its profound thanks to the officials

of Bangladesh Power Development Board & Ghorashal Thermal Power Plant

Station for their support & hospitality and Prime University administration for

providing the administrative support as always.