DBR BTG Electrical

DESEIN PRIVATE LIMITED CONSULTING ENGINEER NEW DELHI

DCR Thermal Power Project (2 x 300 MW), Yamunanagar

DESIGN BASIS REPORT FOR BTG ELECTRICAL SYSTEM

DOCUMENT NO. 50-F248C-D01-01

DEVELOPMENT CONSULTANTS PRIVATE LIMITED CONSULTING ENGINEERS 24B PARK STREET, KOLKATA - 700 016, INDIA

SHANGHAI ELECTRIC (GROUP) CORPORATION (SEC) 3669 jindu Road,shanghai,China

SOUTHWEST ELECTRIC POWER DESIGN INSTITUTE 18 dongfeng Road,chengdu,China

HARYANA POWER GENERATION CORPORATION PANCHKULA, HARYANA

CENTRAL ELECTRICITY AUTHORITY SEWA BHAWAN, R K PURAM, NEW DELHI

RELIANCE ENERGY LIMITED REL TOWER, A-2, SECTOR-24 NOIDA (U.P) – 201301

Design Basis Report for BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram

TPP, Yamunanagar

DOCUMENT NO.: 50-F248C-D01-01 Page 1

DOCUMENT CONTROL SHEET

PROJECT : DCR THERMAL POWER PROJECT 2 X 300 MW UNITS CLIENT : HARYANA POWER GENERATION

CORPORATION DOCUMENT TITLE : DESIGN BASIS REPORT FOR BTG ELECTRICAL SYSTEM DOCUMENT NO. : 50-F248C-D01-01 REV. NO. : 1 ENDORSEMENTS

1 30.12.05 Revised as per MOM with HPGC dt. 05-08 Dec-05

0 01.04.05 FIRST ISSUE LXL / GJ LGR ZJ / RJC REV. NO.

DATE DESCRIPTION PREP. BY SIGN.(INITIAL)

REVW. BY SIGN.(INITIAL)

APPD BY SIGN.(INITIAL)

SOUTHWEST ELECTRIC POWER DESIGN INSTITUTE 18 dongfeng Road,chengdu,China



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CONTENTS

CLAUSE NO. DESCRIPTION PAGE No

1 General....................................................................................... 1

1.1 Intent of Design Basic Report................................................. 1

1.2 Scope of Design ...................................................................... 1

1.3 Design Philosophy................................................................... 1

2 Design criteria of equipment and system ................................... 3

2.1 Generator system.................................................................... 3

2.2 Generator surge protection system ....................................... 21

2.3 Generator neutral grounding system..................................... 22

2.4 Generator Metering ............................................................... 23

2.5 Synchronization..................................................................... 24

3 Equipment description.............................................................. 24

3.1 Generator system.................................................................. 24

3.2 Generator surge protection system ....................................... 26

3.3 Generator neutral grounding system..................................... 27

3.4 Excitation system .................................................................. 28

3.5 Generator Protection Relay................................................... 30

3.6 Generator metering panel ..................................................... 33

3.7 Generator fault recorder panel .............................................. 33

4 Generator control & operation philosophy Records.................. 34

5 Main Equipments list ................................................................ 34



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DRAWINGS DESCRIPTION

50-F248C-D01-02 Single line diagram for generator protection &

metering

50-F248C-D01-03 Generator Protection Action List

ANNEXURE

ANNEXURE I

Sizing calculation for generator neutral grounding system

ANNEXURE II

Date sheet for generator

ANNEXURE III

Generator capability curve

ANNEXURE IV

Generator overfluxing capability curve

ANNEXURE V

Generator saturation curve

ANNEXURE VI

Generator vee curve

ANNEXURE VII

Exciter characteristic curve



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1 General 1.1 Intent of Design Basic Report

In this design basis report, the design criteria and principle of electrical system

and equipment in SEC scope, the equipment main parameters, control &

operation philosophy, metering & protection are described.

1.2 Scope of Design

The design scope of electrical part includes the followings: the generator

control and protection system, generator surge protection and neutral

grounding system,.

1.3 Design Philosophy

1.3.1 Code & Standard

Electrical equipment and system will be designed, constructed, tested and

installed in accordance with the latest editions of IEC codes. Generator will be

as per IEC-34 and their latest amendments, whenever applicable. IE rule shall

be complied for statutory requirement, CBIP guidelines shall be kept in view

for good engineering practice.

1.3.2 Environmental condition

The equipment shall be capable of continuous full load operation under the

following conditions:



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Average Grade Level 270.0Meter (above MSL)

Design Ambient Air Temperature (+) 50 (Max.) (-) 0.6 (Min.)

Wind Pressure 150kg/m2

Highest Average monthly relative humidity 84%

Annual average relative humidity 68% (Max.) 48% (Min.)

Seismic Zone (As per relevant IS) IV

1.3.3 Voltage Levels

Following voltage levels will be adopted for power station auxiliaries.

Energy network apparatus Voltage No. of phases

& frequencyFault Level Grounding

AC motors rated above 175 kW 6600V±10%3Ph, 50 Hz.

(+)/(-) 5%

40KA for 1

Sec

Non-effectively

earthed

AC motors rated up to and

including 175 kW, power

receptacles and three phase AC

loads

415V±10% 3Ph, 50 Hz.

(+)/(-) 5%

50KA for 1

Sec

Effectively

earthed

DC Motors 220 V +10% to

-15% 2 wire DC 25KA Unearthed

Control, indication & protection

circuits for HT/LT circuit breakers

and emergency lighting

220 V +10% to

-15% 2 wire DC 25KA Unearthed

Control & indication for contactor

operated 415 V motors 110V±10%

1Ph，50 Hz,

(+)/(-) 5%

50KA for 1

Sec

Effectively

earthed

Space heater(no more than

1.2kW) for motors and cubicles 240V±10%

1Ph，50 Hz,

(+)/(-) 5%

50KA for 1

Sec

Effectively

earthed

Space heater(more than 1.2kW)

for motors 415V±10%

3Ph,50 Hz,

(+)/(-) 5%

50KA for 1

Sec

Effectively

earthed

Interior lighting, receptacles and

general power 240V±10%

3Ph，50 Hz,

(+)/(-) 5%

50KA for 1

Sec

Effectively

earthed



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2 Design criteria of equipment and system 2.1 Generator system

2.1.1 General description of generator

Two 300 MW generators with stator winding inner water cooled, core and

rotor winding hydrogen cooled, are separately connected to 220kV switchgear

via generator-transformer. The output under VWO condition of generator is

315 MW and the generator have a short circuit ratio of 0.6 ± 15 % tolerance

as per IEC-34 with an inertia constant of generator and exciter of

1.14(kW·s/kVA). Generator rated terminal voltage is 20kV. The generator is

capable of continuous operation at rated output within frequency range of 47.5

Hz to 51.5 Hz and voltage range of 0. 95 p.u to 1.05 p.u. and is capable of

withstanding three-phase, phase-to-phase-to-ground, phase-to-phase, and

phase-to-ground faults, both internal and external, without damage before the

unit shut down by protection.

The generator is provided with class ‘F’ insulation with temperature rise limited

to class ‘B’ insulation limits. The generator enclosure is provided IP54 degree

of protection and the noise level shall not exceed 90 dB at a height of 1.5

meters above the floor level in elevation and at a distance of 1 meter

horizontally from the nearest surface of generator.

2.1.2 Design description of generator

The generator supplied was designed and manufactured under the license of

Westinghouse Electrical Corp.(WEC) in accordance with ANSI C50.10, ANSI

C50.13, IEC34-1 and IEC34-3. It is an updated hydrogen and water inner -

cooled generator, joint - developed by Shanghai Electrical Machinery

Manufacturing Works (SEMMW) (now STGC) and Westinghouse Electric

Corp. (WEC).

2.1.2.1Generator ventilation and cooling system



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The ventilation system provides uniform cooling of the entire generator

frame using hydrogen as the cooling medium. This time-proven system,

supplied on large steam turbine-driven generators for decades, permits a

generator to be designed for optimum physical size and electrical capacity.

Hydrogen gas circulates in a closed circuit inside the generator by two single-

stage axial blowers, mounted on both ends of the rotor. The blowers are

located immediately ahead of the coolers so that the gas temperature rise due

to the blower losses will not be added to the total temperature rises of the

electrical components. All generator components, rotor winding, stator core,

end region flux shield structures and lead box, except the stator winding, are

hydrogen cooled. The hydrogen is cooled by the hydrogen-to-water coolers

located vertically at both ends of the generator. Cold gas from the coolers

flows in two symmetrical paths, with the exception that there is gas flow in the

lead box on the exciter end.

The stator core and rotor winding are cooled by separate but parallel

flow circuits. The air gap serves as a plenum to return the gas back to the

axial blower.

For the rotor, the cold gas is admitted at each end of the rotor through

the annular space under the rotor winding retaining rings. The most part of the

flow enters the main rotor body sub-slots machined underneath each rotor

winding slot. From these sub-slots the gas flows into the radial vent ducts on

rotor winding and discharges into the air gap through holes in the rotor

wedges. A fraction of gas flow is diverted to cool the rotor end turn, This flow

is divided into two paths, the straight and the arc path. For the straight path, it

flows axially towards the main rotor body and discharges through radial ducts

into the air gap. The arc portion of the end turns are cooled by hydrogen

flowing circumferentially towards the pole centerline and discharging into the

air gap through scooped passages at the end of the rotor body.

The stator core is radially ventilated. The cooling gas is forced to the



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space between the core and the generator frame by the axial blowers on both

ends. From this space it flows radially inwards through radial vents and

towards the air gap.

The stator coils, parallel rings, main leads and terminal bushings are

cooled directly with de - ionized water. Cooling water flows from main inlet

pipe into the inlet water manifold, then enters the teflon hose of each coil bar

at exciter end, passes through the whole length of the hollow conductors in

coils and the teflon hoses at the other ends, then exits to the water outlet

manifold at the turbine end where it picks up the drain water from the phase

leads and terminal bushings and returns to the water tank.

Hot water is cooled by water coolers before pumped back to the stator

winding.

2.1.2.2 Frame

The generator is of an integral frame construction, reducing erection

expenses and giving protection to the internal components during

transportation and erection. It may be splitted into 3 sections for shipment in

order to reduce the maximum weight and dimensions for transportation in

conformity with those specified by customers, and is then site - assembled to

be an integral piece, having a good gas-tight frame and maximum protection

to the internal components.

The generator frame is a heavily ribbed cylinder which supports the stator

core and windings, bearing brackets, and rotor assembly. The frame and the

enclosing bearing brackets are fabricated from steel plates.

The generator frame is designed to be “explosion-safe”. This means that

the frame will contain and withstand an internal explosion of the most

explosive mixture of hydrogen and air at the most probable conditions of

occurrence, i.e., at atmospheric pressures during gas changing operations,

without damage to life or property external to the machine. Some internal



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damage may occur with such an explosion.

Four hydrogen coolers each of which has two sections are mounted

vertically at each corner of the generator frame.

The generator frame is supported by frame feet along its length on

foundation seating plates. Foundation bolts resist short-circuit torques applied

to the frame. Shims between frame feet and seating plates are provided for

generator alignment with respect to the steam turbine generator shaft system.

A number of jack screws are also provided in the generator frame feet for

vertical alignment. Axial anchors for the frame feet and also for the seating

plates allow for thermal expansion of the generator in both axial directions

from the centerline of the generator. Transverse anchors engage the bearing

brackets on each end of the generator to maintain the generator lateral

position while allowing the axial expansion.

2.1.2.3 Stator core design

The stator core is composed of high permeability, low loss silicon steel

laminations coated on both side with an effective class F varnish. The

laminations are aligned and held together by dovetail key bars at the outside

diameter which also serve as tension members to clamp the core axially by

means of cast austenitic steel end plates. The end plates are sufficiently rigid

to apply pressure evenly over the core cross section when loaded by the key

bars at the outside diameter. The end plates are non - magnetic and with

sufficient yield strength. The key bars are attached to the spring beams. The

core is thus attached to the frame via the spring beams which reduce the

amplitude of the double frequency core vibratory force transmitted to the

generator frame and foundation. The mounting is such that very little of the

core vibratory force is transmitted to the housing, but the core is rigidly

restrained against load and short circuit torques.

The stator core is tested for integrity during the manufacturing operation



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using a "loop testing" procedure. This procedure which simulates actual

operation consists of circulating rated magnetic flux through the core

laminations and inspecting the core for local hot spots by using a thermal

vision camera capable of detecting small temperature differences. Any local

hot spots, which are indications of deterioration in progress, are to be repaired.

The lack of core problems in SEMMW (now STGC) generators is attributed to

attention to core design and testing for core integrity as described above.

At the bore diameter equally spaced slots run the entire length of the

stator core. These slots extend into the core for assembly of the stator coils.

A copper end-shield with a laminated magnetic shield protects the end plate

and the core tooth area from end region flux.

2.1.2.4 Stator winding design

1. Water cooled stator coils

The stator winding consists of water inner-cooled, single turn, half coils

wound in open slots and secured in place by glass-epoxy wedges. Each stator

coil is made up of two half coils shaped on a former and joined together after

assembly in the slots. The stator coils of this generator are composed of

insulated solid copper strands and insulated hollow copper conductors. Each

strand and hollow conductor is wrapped with an electrical grade continuous

filament type epoxy resin glass fiber to form a smooth continuous uniform

insulation at all points. The strands together with hollow conductors undergo

540°Robel transposition in the slot portion of the coil.. This glass covering is

then treated to give a smooth surface finish which is tough and flexible and

will withstand abrasion from each other in the coil of the stator winding during

operation.

Effective cooling of the stator coils is achieved by the cold deionized

water. The water flows from the inlet manifold at the exciter end of generator

into the coil ends thru teflon insulating hoses, then discharges from the stator



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coil at other end, where it is collected by teflon insulating hoses on a

discharge manifold. The parallel rings and lead terminals are composed of

insulated hollow copper conductors for direct water cooling. All six terminals

of the three phase winding are brought out at the exciter end of the lead box

beneath the floor level through gas tight porcelain bushings.

Resistance temperature detectors are provided to measure the temperature of

the stator coils and their hot water discharge and to detect any abnormal

conditions. Leads from the temperature detectors are connected to terminal

boards.

2. Stator Coil Insulation

Epoxy-Mica insulation is used to provide the ground wall insulation on the

stator coil. To give good dielectric and mechanical strength, the ground

insulation is continuously wound with several layers of epoxy resin mica-

paper tape then cured at high pressure and temperature in the former.

Epoxy-Mica insulation is a tough, yet thermally flexible dielectric barrier with

excellent electrical and physical properties. The excellent dielectrical

properties of the resin, coupled with good insulation consolidation, results in

Epoxy-Mica with lower dielectric loss tanδ , increased dielectric strength, and

remarkable improvement of voltage endurance. Its consistently low dielectric

loss is less affected by temperature and voltage variation than other types of

insulation. Epoxy-Mica insulation has great thermal endurance and long life.

The character of the resin provides solid, yet elastic physical bonds between

mica papers. The resilient nature of the resinbond permits elastic cyclic

displacement of adjacent mica papers and provides restoring force within the

insulation ground-wall. This makes Epoxy-Mica insulation ideally suitable for

cyclic duty operation. The insulation is also inert to ordinary chemicals, oils,

and solvents and has an unusually high moisture resistance. Continued

improvements have made Epoxy-Mica insulation a superior insulation for

high-voltage coils, satisfying the requirement of class F insulation.



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Effective corona suppression is provided by the use of a low-resistance,

conducting varnish on the coil slot section to contain the dielectric stress

within the solid insulation and a combine process of a low resistance

conducting varnish and a high-resistance, semi-conducting varnish in the end-

turns to grade voltage stress along the coil surface.

Quality Assurance checks are performed on each coil and the complete

winding to verify insulation integrity. Each coil is given a high-potential test

well in excess of final winding high-potential test values before being wound

into the machine. Each set of coils includes extras which are chosen at

random from the set for testing to destruction, thus giving further verification of

insulation integrity. Additional high-potential tests are performed both during

and after completion of the stator winding.

3 . Stator Winding Bracing

Of equal importance with the insulation system is the method of slot-fill

and bracing used to protect the stator coils from the vibratory stresses

experienced during steady-state operation and from the transient disturbances

which can be experienced during abnormal operating conditions. The ANSI

and IEC Standards set the requirements for steady-state operation and define

the abnormal operating conditions which must be met.

Each coil is secured in the slot by a glass-epoxy wedge assembled in wedge

grooves in the slot. Epoxy impregnated conforming materials are placed under

the bottom coil and between the bottom and the top coils to suit the coil in slot.

The tightness is maintained by the prestressed driving strip (PSDS or ripple

spring)-- a wave glass fiber epoxy strip-- directly below the slot wedge,

maintaining radial pressure on coils and slot wedges.

Flat glass-epoxy filler strips are assembled above the coils in the slots to

distribute the load of the PSDS.

Flat filler strips are also utilized on one side of the coil to provide a tight fit



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in the slot. These supporting members virtually eliminate potentially damaging

coil vibration caused by the electromagnetic forces that are present. The

entire stator is thermally cured under pressure to consolidate slot contents

and reduce vibratory stresses due to coil motion. The consolidation of ground

wall and filler materials and the use of ripple spring between coils and wedges

gives unsurpassed slot compactness for long service life.

The radial winding clamp composed of high-strength glass epoxy

clamping plates and non-magnetic bolts together with support rings and

bracing brackets provides radial, structural consolidation of the end winding.

The radial clamps provide clamping forces well in excess of the vibratory

forces between the top and bottom coils. This reduces vibration of the

individual coils relative to the strain blocks used between top and bottom coils,

as well as to the diamond spacer assemblies used between adjacent coils.

This reduced radial vibration will prevent relative motion and wear between

the coils and the strain blocks. Clamping plates and non-magnetic bolts

secure the coils to the bracing brackets.

De-coupled end winding support bracing consist of bracing brackets,

teflon slip layers and spring structure through which the bracing brackets

attach to the core end plates so as to de-couple the end windings from the

core and to improve the end winding to radial brace attachment. The brace

provides for dynamic isolation between the coils and core to permit detuning

of the end winding natural frequency well below 100 Hz, the exciting

frequency.

There are Fluoroelastomer rubber layers with good physical and dielectric

properties placed between the insulating clamp plates and coils for protecting

coil from wear of insulation, as well as for damping coil vibration.

This end-winding bracing system has effectively controlled the forces

which result from both steady and short circuit conditions and also allows axial

motion for thermal expansion as proved by long operation practice.



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This bracing design is found in the fact that, by isolating the stiffness of

the core from the end winding support, the end winding dynamics can be

favorably changed.

4 Main leads

Stator parallel rings, phase leads and main lead bushings are directly

cooled by the water. The main lead bushings are assembled in a gas-tight

main lead box located underneath the frame at the exciter end. Bushings can

be replaced without removing the generator rotor. The six main lead bushings

extend from the lead box, three of which are used for the main leads

connecting to the main transformer and three of which are used to form the

neutral tie. Each bushing can be provided with up to four bushing mounted

current transformers. Current transformers are suitable for metering, relaying,

or voltage regulator service. The current transformers have a secondary

current level of five amperes.

2.1.2.5. Generator rotor

The cylindrical type rotor forging is made from chromium, nickel,

molybdenum, vanadium alloy steel and is poured with the vacuum degassing

process. Forging materials are ultrasonically tested for compliance with rigid

quality assurance specifications. A bore hole is provided to remove

centerline indications. The bore hole may then be used in later years for

examination of forging integrity. Two pole rotors have their pole faces slotted

so as to equalize flexibility and to reduce double-frequency vibration.

Rotor winding components are subjected to stresses both from rotation

and from thermal expansion and contraction. It is essential that these stresses

be accounted for and limited in the rotor design. During startups, shutdowns,

and load changes the rotor winding will move relative to the rotor structural

parts. Built-in clearances and slip layers allow for this motion while reducing

the frictional forces which could cause distress or shaft vibration. Hard-drawn,



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creep resistant, silver-bearing copper and glass-laminate turn-to-turn

insulation reduces the chance of permanent winding deformation or shorted

rotor turns. The winding is held firmly against rotational forces by

nonmagnetic retaining rings and high-strength rotor slot wedges. In the rotor

end turn area, customarily fitted glass epoxy blocking and spacers maintain

alignment of the winding components. The end winding curved sections

potentially high stress areas are arranged with brazed connections located

well away from the curves. Axial expansion is controlled by allowing for

expansion to occur and by including teflon slip layers in the rotor slots and

under the retaining ring, to limit the friction that opposes axial motion.

The field winding is manufactured from high-strength alloy copper. This

silver-bearing alloy copper contains the necessary metallurgical creep-

resistant properties to minimize distortion during operation. The individual

turns of the rotor winding are made up of two conductors. On the end turns

each consisting of two copper channel sections, which form a gas passage for

the hydrogen. For turns inside slots, there are two parallel rows of slim vent

ducts evenly distributed along the winding slots to form radial vent holes over

the sub-slots. The field winding insulation is provided with extra creepage

distance on the top turns. The windings are placed in rectangular slots which

are lined with one piece, molded insulating slot cells. The slot cells are teflon

lined on the inner surface to permit the rotor copper to move axially due to

thermal expansion and contraction. The insulation between turns consists of

glass laminate bonded to the copper. The glass laminate exhibits excellent

wear characteristics and has a high coefficient of friction, which reduces

relative slippage between coil turns that causes wear and copper dusting.

Instead, the entire coil slot structure acts as a unit rather than individual turns.

After the rotor is pressed and cured, fitted, high-strength slot wedges are

driven into the top of the slots.

The rotor end turns are supported radially against rotational forces by



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18Mn18Cr nonmagnetic retaining rings shrunk onto the rotor body. This alloy

is highly resistant to corrosion and stress corrosion cracking in the presence

of moisture and other corrodents. These retaining rings are nonmagnetic steel

forgings. These floating-type retaining rings, with teflon surfaced insulating

liners, prevent distortion of the rotor copper and abrasion of the rotor coil

insulation. The rings are shrunk and keyed onto machined sections at the

ends of the rotor body with a firm fit at overspeed and rated temperature. The

heavy shrink fit provides a low-resistance electrical path for induced rotor

surface currents, thereby reducing heating due to rotor surface currents. A

circumferential locking ring is provided to prevent axial movement of the

retaining ring. This method of support permits the shaft to flex without causing

fretting at the joint or overstressing the rotor winding and is used to eliminate

the effect of shaft deflection on the rotor end winding assembly.

An amortisseur winding is provided which uses copper damper bars in

each rotor slot connected at the ends by beryllium copper wedges to the

retaining rings. This design meets the requirements of the industry standards

for negative-phase-sequence current capability.

This machine has two single stage blowers, mounted on the rotor shaft at

both ends. The outside diameter of the blower blades is smaller than that of

the retaining ring. The blower hub outside diameter is designed to be small

enough to allow removal of the retaining ring over it, if necessary, for winding

inspection. After unshrunk from the retaining ring, the end plate can be slided

ver the spacer ring and attached to the blower hub during repairing.

The completed rotor is dynamically balanced. It is carefully baked and

seasoned at running speed to promote lasting stability of the rotor winding

components. Standard equality control tests are made on every rotor before

and after over-speed tests to verify that no shorted rotor turns have developed.

It is performed by means of a continuous impedance test as the rotor speed

is increased from rest up to rated speed and back to rest. The rotor is then



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carefully inspected and a final high-potential test is performed.

2.1.2.6 Bracing gland seal and bearing brackets

The bearings, supported in rugged fabricated bearing brackets, are

insulated and may be removed without removing the hydrogen seals from the

machine. Bearing and gland seal insulation is provided at the following places

on both ends of the generator to prevent shaft currents from flowing through

the bearings: between the bearing pad and the bearing seat; between the

gland seals and the brackets; between the bearing oil seals and the

brackets; and at the stop dowel and bearing key. In addition, the pieces on the

exciter end are "double insulated" with terminals for checking the insulation

resistance of the bearing and gland seal insulation during operation. Only the

exciter end bearing is "double insulated". Since the combination of insulation

and the shaft grounding brushes, which are located on the turning gear

pedestal, is considered satisfactory for preventing bearing currents in the

turbine end bearing of the generator. The ring type gland seals are also

housed in the bearing brackets to maintain a gas-tight shaft seal. The shaft

seals are of double oil flow construction with separate air and hydrogen side

oil supplies to reduce hydrogen consumption. Vibration detector probes are

provided at each bearing. The bearings are forced lubricated and visual oil

flow gauges are supplied in the bearing bracket oil piping.

2.1.2.7Lubricating supply system

The generator shares a common lubrication system with the turbine.

Fewer subsystems mean less complexity and reduced installation costs.

2.1.2.8Seal oil system

The function of the seal oil system is to lubricate the seals and prevent

hydrogen escaping from the generator, without introducing air and moisture



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into the generator. The same oil is used in the turbine and generator bearing

lubrication oil system and the gland seal oil system. Under normal operating

conditions the seal oil is completely separated from the lubrication oil.

Independent seal oil systems for air-side and gas-side oil eliminate the need

for an oil vacuum treating unit and reduce hydrogen consumption by

preventing the air-side oil which contains moisture from contacting the

hydrogen gas in the generator. Part of the reliability of the system is the

back-ups provided. Emergency seal oil back-up pumps, interconnected with

the lubrication oil system, automatically provide continuous operation of the

seal oil supply in the event that the main air side oil fails.

2.1.2.9 Hydrogen gas system

Hydrogen pressure is maintained at the design pressure by a pressure

regulator located in the hydrogen system. Continuous circulation of the

hydrogen is maintained by the shaft-mounted axial blowers. The hydrogen

gas system is designed for the following functions:

To provide means of safely putting hydrogen in and taking hydrogen out

of the generator, using carbon dioxide as a scavenging medium.

To maintain the gas pressure in the generator at the desired level.

To continuously monitor the condition of the machine with regard to gas

pressure, temperature, and purity, and to provide alarm signals in the event of

abnormal conditions in the gas system. The pressence of liquid in the

machine is also indicated by an alarm.

To dry the gas and remove any water vapor which might get into the

machine from the seal oil system or other sources.

To provide control to secure the system in the event of an abnormal

condition.

— Gas dryer

A gas dryer is connected across the generator fan so that gas is



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circulated thru the dryer whenever the machine is running.

— Liquid detectors

Float operated switches in small housings are provided under the

generator frame and under the main lead box to indicate the presence of any

liquid in the generator which might be due to leakage or condensation from

the cooler. Openings are provided in each frame ring at the bottom of the

frame so that any liquid collected will drain to these water detectors. Each

detector is provided with a vent return line to the generator frame so that the

drain line from the generator frame will not become air bound. Isolating valves

are provided in both the vent and drain lines so that the switches can be

inspected at anytime, and a drain valve is provided for the removal of any

accumulated liquid.

— Hydrogen purity monitoring equipment

The purity of the gas in the generator is determined by the use of the

purity blower, the hydrogen purity electronic differential pressure transmitter,

the hydrogen pressure electronic transmitter, and the hydrogen gas

instrumentation package.

An induction motor, loaded very lightly so as to run at practically constant

speed, drives the purity blower and circulates the gas drawn from the

generator housing. Thus, the pressure developed by the purity blower varies

directly with the density of the sampled gas. The hydrogen purity differential

pressure transmitter measures the pressure developed by the purity blower.

Gas density is dependent upon the ambient pressure and temperature as well

as the purity.

The hydrogen monitoring system combines the purity blower differential

pressure and the machine gas pressure signals to provide a compensated

density signal, which is a true reading of machine gas purity.

The purity indicator scale is divided into three sections. Near the center of



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the scale is a point marked "100% Air". This point provides a means of

calibrating the indicator without removing the gas from the generator. The

upper end of the dial consists of a scale showing the percentage of carbon

dioxide present in a mixture of carbon dioxide and air. This portion of the scale

is used during scavenging operation when carbon dioxide is being introduced

into the generator. The lower end of the dial consists of a scale indicating the

percentage of hydrogen present in a mixture of hydrogen and air. It is this

portion of the scale which is used during normal opration of the machine to

determine the purity of the hydrogen in the generator housing.

The hydrogen purity signal, an electrical output signal, may be carried to

a remotely located receiver provided with a dial similar to the purity indicator

on the generator auxiliaries control enclosure.

Two switch assemblies are provided with the hydrogen monitoring system

which are set to produce a "hydrogen purity high or low" alarm when the purity

signal falls below exceeds predetermined limits.

— Generator fan differential pressure monitoring equipment

An electronic differential pressure transmitter is connected directly to the

generator housing and senses the pressure developed by the fan mounted on

the generator rotor. The hydrogen monitoring system transmits the generator

fan differential pressure signal to an indicator in the generator auxiliaries

control enclosure.

This pressure can be used as a check on the purity indicator or can be

used to indicate the hydrogen purity if the purity indicator is taken out of

service while the generator is running.

— Hydrogen pressure monitoring equipment

The electronic hydrogen pressure transmitter is connected directly to

generator housing an senses the pressure within the generator. The

transmitted pressure signal is used by the hydrogen monitoring system, not



TPP, Yamunanagar


1

only to compensate the density for purity as mentioned above, but also to

supply the electrical signals for the following:

The hydrogen pressure indicator in the generator auxiliaries control

enclosure.

A remotely located indicator with dial similar to the previous indicator

High and low pressure alarm switches located in the generator auxiliaries

control enclosure.

The high and low pressure alarm switches provide an indication when the

gas pressure in the machine exceeds or goes below predetermined limits.

— Hydrogen temperature alarm

A hydrogen cold gas thermostat is located in the generator to provide a

source of alarm in case the temperature of the hydrogen in the generator

becomes excessive.

— Supply pressure switch and gauges

All generators are equipped with a hydrogen pressure control, which has

a supply pressure switch and two pressure gauges. The top gauge indicated

the machine gas pressure and also the setting of the regulator on the

hydrogen pressure control. The bottom gauge gives an indication of the

amount of pressure available from the hydrogen supply system.

A pressure switch is located on the supply side of the hydrogen pressure

control manifold and gives and alarm when the supply pressure is low. A drop

in pressure at this point would mean that the available pressure from the

hydrogen supply was to low, or that the regulators in the hydrogen supply are

set at too low a pressure.

2.1.2.10. Stator coil water system

The stator coil water system is a closed loop system having the following



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1

features:

-Circulation of high purity water thru the stator coil hollow conductors for

removal of heat due to the stator coil losses.

-Dissipation of heat from the high purity water.

-Filtering of water to remove foreign material.

-Demineralization of the water to control its electrical conductivity.

-Instrumentation and alarms to continuously monitor and advise

conditions of conductivity, flow, pressure, and temperature of water.

-All piping and components are made of corrosion resistant materials.

Cold water is piped thru the generator shell into a circumferential manifold

in the exciter end of the generator. The cold water inlet piping is e quipped

with a temperature detector for temperature monitoring and a thermostat for

alarm purposes. An inline strainer is installed for startup to prevent admission

of dirt into the hollow stator conductors.

Inside the generator, water flows from the inlet manifold into the coil ends

thru teflon insulating tubes. Water discharging from the stator coil at the other

end, is collected by teflon hoses and a discharge manifold, and then returns to

the water tank.

The two inlet and discharge manifolds are interconnected at the high

point with a vent line which also serves as an anti-siphoning line. This vent is

continued to the water tank. The two manifolds are connected to a differential

pressure gauge to indicate pressure drop across the stator coils. They are

also connected to differential pressure switches for alarms for abnormal

pressure drops across the stator coils. The inlet end of the water manifold is

also connected to an inlet water pressure gauge and to the low pressure side

of a differential pressure switch. The high pressure side of this switch is

connected to the generator (gas pressure). When the generator gas pressure

drops to 0.35 bar above the inlet water pressure, an alarm is actuated.



TPP, Yamunanagar


1

2.1.2.11 Auxiliary alarms

An alarm signal system is associated with the seal oil, stator coil water

and hydrogen gas systems to indicate abnormal operating conditions. A

Generator Auxiliary Control Enclosure has been supplied to indicate these

alarms. A recent improvement has been made to supply the alarm signals

dependent upon whether or not DEH is supplied and on the level of DEH

supplied standard option. The traditionally supplied Generator Auxiliary

Control Enclosure with local panel/announciator with limited contacts for

Customer's use in addition to contact and analog signals going to DEH. DEH

makes all calculations and displays on CRT under appropriate conditions.

2.1.2.12 Hydrogen coolers

Each hydrogen cooler consists of a number of finned tubes arranged

within a suitable open frame structure, thus providing a layer heat transfer

surface for cooling the hydrogen gas circulating within the generator.

Technically a hydrogen cooler is classified as 1-2 cross flow heat exchanger.

That is the hydrogen gas makes a single pass through the cooler on finned

side of tubing and the cooling water makes two passes on the tubes.

Generally hydrogen coolers are divided into 2 "sections", each section being

an independent heat exchanger. The sections are arranged in tandem such

that the hydrogen gas makes a single pass through all the tandem sections,

whereas the cooling water flows in parallel in each section and makes two

passes in each.

There are generally two arrangements of hydrogen coolers used in

generators: one is with coolers vertically mounted; and the other is with cooler

horizontally mounted. This design uses the vertical arrangement.

In the vertical arrangement, there are four hydrogen coolers, mounted in

the frame of the generator at four corners. Each cooler consists of two

separate, tandem sections, making a total of eight sections, each of which can



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1

be isolated by valving.

Each cooler is attached to the generator frame at one end only to permit

expansion and contraction within the generator. The inlet water chamber,

which extends beyond the generator frame, is bolted to the generator frame.

A thin steel diaphragm is secured to the cooler and to the generator frame at

the opposite end of the cooler. This diaphragm allows relative thermal

expansion between the generator frame and the hydrogen cooler without

allowing hydrogen gas to escape. The water makes two passes through each

section in a counter flow manner by means of a reversing chamber at one end.

The heat is transferred from the gas to the cooling water flowing through the

finned tubes of the cooler.

Temporary operation at reduced load is permitted with one or two of the

eight cooler sections out of service. The permitted load can be seen from the

generator instruction book in detail.

2.2 Generator surge protection system

The surge arrestors and capacitors for each phase protect the generator and

3 sets of potential transformers from voltage surges. This system also senses

voltage for metering, relaying, and automatic voltage regulation. The system

includes the following major components:

a) Surge capacitors for each phase.

b) Surge arresters for each phase.

c) Three sets potential transformers for each phase.

Three separate compartments, one for each phase and each separated from



TPP, Yamunanagar


the other by grounded metal barriers to maintain the integrity of the isolated

phase bus duct, shall be provided. Capacitors, surge arresters, and potential

transformers will be connected phase-to-ground. Potential transformers will be

fused on both the primary and secondary sides. The surge capacitors, surge

arresters, and potential transformers that connect to the main isolated phase

bus duct are enclosed in the surge arrester and potential transformer cabinet,

the PT installed in the cabinet shall be draw out type. The cabinets located on

the 6.3m floor of turbine house near the main isolated phase bus duct..

The Generator Surge Protection System will be designed for maximum gen-

erator output at any voltage from 95 to 105 percent of rated voltage and a

phase-to-ground fault on the connected equipment.

Please refer to ‘single line diagram for generator protection metering’,

drg.no.50-F248C-D01-02 for connection of potential transformers.

2.3 Generator neutral grounding system

The neutral grounding system provides a high resistance path between the

generator neutral and ground to limit the overvoltage within approximate 2.6

p.u. under phase to ground fault, and also provides a means for detecting

phase-to-ground fault currents. The system includes the following major

components:

a) Dry type neutral grounding transformer (NGT).

b) Resistor connected to secondary winding of NGT.

c) Current transformers on both side of NGT.



TPP, Yamunanagar


The maximum normal design conditions will be maximum generator output at

any voltage from 95 to 105 percent of rated voltage. The emergency design

condition is a phase-to-ground fault on the connected equipment.

The high resistance neutral grounding unit shall consist of a neutral grounding

transformer rated for short time overload and a secondary resistor of

chromium, aluminum and iron alloy rated for 10 Sec short time loading. The

primary winding of the distribution transformer will be connected between the

generator neutral connection and ground while the secondary winding will be

connected to the secondary resistor. A protective relay with a harmonic filter

will be connected to the secondary winding to sense ground current flow and

will initiate a unit trip through the Unit Protection System.

The rated primary voltage of the NGT is rated phase to phase voltage of the

generator. The kVA rating of the NGT will be based on a 5 minute duty. The

NGT will be so chosen that the capacity of it shall be more than the energy

loss in the resistance. Please refer to annexure I: Sizing calculation for

generator neutral grounding system.

The value of secondary resistance is so chosen that the energy loss in the

resistor is equal to or more than the capacitive kVA of the generator windings

and the equipments connected with generator.

The NGT cabinet is located on the 6.3m floor of turbine house near the neutral

point terminal of generator.

2.4 Generator Metering



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1

The current, voltage, watt, var, frequency, power factor of the generator and

exciter field current and voltage will be measured by discrete type static

meters with DCS connectivity. Generator metering will be achieved through

micro processor based Energy meter (kWH & VARH meter) with DCS

interface facility. The energy meter as well as the discrete meters will housed

in a stand alone type Generator metering panel and shall be located in Unit

Control Room.(Please refer the Generator metering disposal diagram shown

on drawing No. 50-F248C-D01－02)

2.5 Synchronization

Auto synchronization of GT 220kV circuit breaker will be performed through

DCS . Back-up manual synchronization through sync check relay is provided

across GT 220 kV circuit breaker. 3 Equipment description

3.1 Generator system

3.1.1 Type & cooling method

Manufacture: Shanghai Turbine Generator Co, ltd

Type: QFSN-300-2

Cool method: stator winding and terminal bushing is water inner-cooled, the

rotor winding is hydrogen inner-cooled and stator core hydrogen cooled.

Excitation type: brushless excitation system with permanent magnet pilot

exciter



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1

3.1.2 Main technical data

Rated capacity:353 MVA

Rated active power: 300MW

Output under VWO condition: 315MW

Rated voltage: 20kV

Rated current: 10189A

Frequency: 50Hz

Power-factor:0.85(lag)

Rated speed: 3000r/min

Efficiency: 98.8%(guaranteed value with no negative tolerance.)

98.93%(designed value)

Excitation system ceiling voltage:2 times

Rated field current: 2510A

Rated field voltage: 302V

Gen. no load field current: 987A



TPP, Yamunanagar


Gen. no load field voltage (75):113V

Stator winding resistance(15) : 0.00212Ω

Rotor winding resistance(15) : 0.0923Ω

Stator winding capacitance to ground per each phase: 0.209μF

Xd” (Sub-transient reactance (direct axis saturated)): 0.16

Xd’ (Transient reactance (direct axis saturated)): 0.202

Rotor rotating direction: clockwise direction (from turbine side to generator

side)

Terminal Phase physical location: C、B、A(Viewing from the exciter side to

generator side ,and from left side to right side)

The other data for generator refers to annexure II Date sheet for generator

3.2 Generator surge protection system

3.2.1 Surge capacitors for each phase:

capacitance：0.25µf

3.2.2 Surge arresters for each phase：



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1

Rated voltage: 24kV

Normal discharge current: 5kA

Residual voltage:56.2 kV

3.2.3 Potential transformers

for each phase：

fuse:5A，rupturing capacity:5500MVA，3set

A PT’s: kV311.0/

311.0/

311.0/

320 ,1set

B PT’s: kV311.0/

311.0/

311.0/

320 ,1set

C PT’s: kV311.0/

311.0/

311.0/

320 ,1set

3.3 Generator neutral grounding system

3.3.1 Dry type neutral grounding transformer (NGT).

Type: dry type, single phase

Capacity: 50kVA for 5 minutes



TPP, Yamunanagar


Ratio: 20/0.24kV

3.3.2 Secondary resistor.

Resistance: 0.274Ω

Tap voltage: 110V

3.3.3 Current transformers on primary side of NGT.

Class: 0.5

Ratio: 10/5A

3.3.4 Single phase disconnector:

Rate voltage: 20 kV

Rate current: 400A

3.4 Excitation system

Excitation system will be brushless rotating diode wheel with a permanent magnet generator (PMG) excitation system. The exciter will be capable of maintaining field current for a 30 percent voltage depression on the machine terminals. The system shall be capable of providing 1.4 times nominal field voltage when the machine terminal voltage is 70 percent rated voltage. The excitation system will reach 95% of the difference between ceiling voltage and rated excitation voltage within 0.1 second. The ceiling voltage shall be maintained for a minimum of 10 seconds. The



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1

excitation system response ratio shall not be less than 2.0 per second. The generator and its excitation system shall be provided with class ‘F’ insulation with temperature rise limited to class ‘B’ insulation limits.

The proposed BLE excitation system was Westinghouse technology which is fully transferred to STGC.

The features of brushless excitation system:

- The electric power source of excitation comes from the directly driven AC

exciter and permanent magnet pilot exciter to avoid system interference.

- Slip ring and brushes are no longer used. Thus pollution caused by carbon

dust is eliminated, noise level lowered, and maintenance becomes easier.

- The modular structure of rectifier, fuse and etc, is easy for maintenance.

-Enough back up capacities are available for critical components such as the

rotating diodes, firing circuit, power amplifying circuit and stable voltage source to

ensure the safe operation.

-With better protection devices (such as over excitation, low excitation and low

frequency protection) the generator can be operated at the maximum output.

-Internal connection: Rotating elements are solidly connected together. No

outer connection is needed between the generator field and the exciter, the only

outer connection being those between the stator of the AC exciter, the stator of the

pilot exciter and the control circuit.

-The field current of generator can be indirectly measured.

- De-excitation is realized by field inversion of the AC exciter and then open of

its field connection to PMG.

The following protective and limit circuits will be provided for the system

stability and protecting the interconnected components: volts/hertz regulator,



TPP, Yamunanagar


reactive current compensator, over excitation/ under excitation limiters and

power system stabilizer (PSS), etc.

The excitation system will include exciter, permanent magnet pilot exciter,

regulator panel, converter suppression panel, field grounding detector panel,

manual excitation control panel. All the panels will be IP54 degree of

protection and housed in Electrical Relay Room (ERR).

The above panels will be fabricated from steel structural sections or pressed

and shaped cold-rolled sheet steel of thickness not less than 2mm, the panel

size will be 2260(H)x800(W)x800(D).The protection degree for generator

protection panel will be IP52.

3.5 Generator Protection Relay For each unit, one (1) set of doubly numerical multi-function Generator

protection systems will be provided. The relay will be equipped in two (2)

pieces of Generator protection panel and housed in ERR. Protection relay will

provide detection and corrective/isolation action as required for the following

faults and malfunctions: (The Generator protection disposal diagram is shown

on drawing No. 50-F248C-D01－02)

1) Generator Differential (87G)

2) Stator Inter-turn fault (95)

3) Stator earth fault 95 % and 100 % (64G)

4) Loss of excitation (40)



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1

1

5) Negative phase sequence current (46)

6) Reverse power (32G1 / G2)

7) Low forward protection (37G)

8) Over current (51V)

9) Rotor earth fault (detect) (64R) - only feature

10) Over-voltage (59)

11) Under-voltage (27)

12) Generator pole slipping (90)

13) Under/over frequency (81U / O)

14) Voltage balance (60)

15) Over flux (99)

16) Overload (49)

17) Generator Backup impedance (21G)

18) Generator cooling water-loss (30G)

19) Stator winding temp high



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1

20) Rotor winding temp high

21) Dead machine protection (96)

22) VT and CT supervision (98)

23) Startup/Shutdown protection (64SS)

Start up/Shut down Protection is a protection which is used to react the stator

earth fault and the interphase fault under low frequency or low speed

conditions.

Start up CBF is a protection which is used when the circuit breaker rejects

tripping.

A micro-processor based rotor current supervision and overheat protective

device (WZFD) will be provide for rotor winding temperature high protection.

Voltages and currents of stator winding are sampled; Take the generator’s

electrical-magnetic parameters and characteristic curve into consideration, the

rotor’s current and negative sequence current can be calculated through the

patent algorithm. The rotor winding temperature high alarm (or trip) signal can

be issued if rotor current or negative sequence current reaches their settings

respectively.

Multiple generator lockout relays shall be used to receive signal inputs from

protective relays and to provide the contacts needed to initiate protective

action and alarms. Protective relays shall trip lockout relays based on

functional redundancy. All lockout relays shall have a manual reset feature

which shall request the operator to manually reset the lockout relay prior to



TPP, Yamunanagar


1

returning the affected equipment to service. Protective trip status/alarm will be

displayed in DCS (DCS) CRT.

Time synchronization will be supplied with the master clock/ GPS. Events

Records, Fault Record and Data Logging will have sufficient storage capacity.

The complete software of the protection scheme will be supplied in a laptop

for each unit.

The Generator protection panel will be fabricated from steel structural sections

or pressed and shaped cold-rolled sheet steel of thickness not less than 2mm,

the panel size will be 2260(H)x800(W)x600(D).The protection degree for

generator protection panel will be IP52.

3.6 Generator metering panel

Generator metering panel will be provided and housed in CCR to install the

meters of Generator.

Generator metering panel will be fabricated from steel structural sections or

pressed and shaped cold-rolled sheet steel of thickness not less than 2mm,

the panel size will be 2260(H)x800(W)x600(D). The protection degree for

generator metering panel will be IP52.

3.7 Generator fault recorder panel

One (1) piece of Generator Fault Recorder Panel will be provided and

housed in ERR to recorder electrical parameter of Generator when Generator

fault and malfunctions for each unit.

Generator Fault Recorder Panel will be fabricated from steel structural



TPP, Yamunanagar


sections or pressed and shaped cold-rolled sheet steel of thickness not less

than 2mm, the panel size will be 2260(H)x800(W)x600(D). The protection

degree for generator Fault Recorder panel will be IP52.

4 Generator control & operation philosophy records

The Generator will be controlled from Power House Central Control

Room (CCR) through DCS. The DCS will be utilized to perform control,

interlock, indication, metering and annunciation related to the above

equipment including equipment pertaining to Generator auxiliary system. All

controls as supplementary to the proprietary system of BTG including auto

synchronization of generator with 220kV grid will also be performed form DCS.

6.6 kV / 415V Electrical Breakers of Main Power house & ESP PMCC and

Emergency DG set shall be operated from DCS. Balance of plant Electrical

system will be operated from localized Electrical Control Panel (ECP).

Detailed control and Operation philosophy shall be in line with DESIGN BASIS

REPORT FOR ELECTRICAL CONTROL & OPERATION PHILOSOPHY _

doc no..:REL-DCRTP-CEE-299-R-517.

5 Main Equipments list

Design Basis Report for BTG Electrical System HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar


1

Quantity No. Name Type & specification Unit

1＃ 2＃ total Remark

1. Generator system

1.1 Generator equipment(electrical part）

1.1.1 Bushing CT Supplied by generator

manufacturer

12000/5A 5P20 60VA set 15 15 30

12000/5A 0.2 60 VA set 3 3 6

12000/5A 0.2S 60VA set 6 6 12

1.1.2 Terminal box for connection the IPBD to generator

set 1 1 2 Supplied by REL

1.2 Rotating brushless excitation system set 1 1 2

1.3 PT & LA cabinet 1(2)0AAA01~03



1



including：Fuse，RN4－20，0.5A，Rupturing capacity:5500MVA， set 9 9 18

PT：JDZJ－20 kV

311.0/

311.0/

311.0/

320 set 3 3 6

PT：JDZJ－20 kV

311.0/

311.0/

311.0/

320 set 3 3 6

PT：JDZJ－20 kV

311.0/

311.0/

311.0/

320 set 3 3 6

LA：Y5W1－24/56.2 set 3 3 6

Capacitor：0.25μf set 3 3 6

1.4 Neutral point grounding transformer cabinet

including ： dye-type single phase transformer: 50kVA 20/0.24Kv set 1 1 2 1(2)0MK01

Secondary side resistance :0.274Ω，tap voltage:110V



1



CT： 0.5 10/5A

Single phase disconnector：GN2－20/400 400A

2 Excitation system set 1 1 2

2.1 Exciter 1650kW, 475V, 3474A, exciter efficiency:90% set 1 1 2

2.2 Permanent magnet pilot exciter

33.24Kva/31.6kW, 95V, 202A, 3000rpm, 350Hz set 1 1 2

2.3 Regulator panel Size: 2260(H)x800(W)x800(W) piece 1 1 2

2.4 Converter and suppression panel

Size: 2260(H)x800(W)x800(W) piece 1 1 2

2.5 Field grounding detector panel

Size: 2260(H)x800(W)x800(W) piece 1 1 2

2.6 Manual excitation control panel

Size: 2360(H)x800(W)x800(W) piece 1 1 2

2.7 Manual excitation adjust panel Size: 2360(H)x800(W)x800(W) piece 1 1 2



1

1

1



2.8 AVR test panel Size: 2200(H)x800(W)x640(W) piece 1 1 2

3 Generator protection panel 220V DC, 240V AC, CT:5A, PT:110VSize: 2260(H)x800(W)x600(W) piece 2 2 4

4 Generator metering panel 220V DC, 240V AC, CT:5A, PT:110VSize: 2260(H)x800(W)x600(W) piece 2 2 4

5 Generator fault recorder panel

220V DC, 240V AC, CT:5A, PT:110VSize: 2260(H)x800(W)x600(W) piece 1 1 2

6 Generator synchronization panel

220V DC, 240V AC, CT:5A, PT:110VSize: 2260(H)x800(W)x600(W) piece 1 1 2

7 Terminal box piece 2 2 4

8 DC drive & control box Size: 1600(H)x800(W)x600(W) piece 5 5 10

9 Control cable km 5 5 10



TPP, Yamunanagar


Annexure I: Sizing calculation for generator neutral grounding system

1 Base data

（1）Capacitance of generator:

phasefC /209.01 µ=

（2）Capacitance of main transformer’s LV side (according to the data

provided by REL):

phasefC /036.02 µ=

（3）Capacitance of auxiliary transformer’s HV side (reference value):

phasefC /005.03 µ=

（4）Capacitance of IPBD (according to the data provided by REL):

phasefC /002.04 µ=

（5）Capacitance of Surge capacitor

phasefC /25.05 µ=

2 Sizing calculation

Each phase total capacitance of the generator and the equipments connected



TPP, Yamunanagar


1

1

with the generator

phasefCn

/507.0002.02005.0036.0209.025.0

µ=+×+++=∑

Three phase capacitance to ground: Ω=∑

×= 83.20932

131

ncg Cf

Xπ

The generator neutral point resistance should be equal to or less than Xcg：

Ω=== 48.19031.1

83.20931.1

' cgXR

Basis for the factor 1.1:The safety factor is according to the Chinese

Electrical Design reference book.

Ratio of neutral ground transformer： 33.83240

1020 3

=×

=N

The resistance of the neutral grounding transformer secondary side:

Ω=== 274.033.83

48.190322

'

NRR

The current of neutral grounding transformer secondary side:

AR

UIr 506274.03

2403

2 =×

=×

=

The rating of the resistance:



TPP, Yamunanagar


1

kWR

UPr 07.7010274.03

2403

322

2 =××

== −

NGT capacity:

rPS ≥

Base on the 5 minutes overload capacity of dye type transformers, over load

factor is 1.6:

Basis for the factor 1.6 :the over load factor is according to the Electrical

Design reference handbook for China Power plant

The over load factor of the dry type transformer can be changed as follow:

Overload time: over load factor:

5 minutes 1.6

18 minutes 1.5

32 minutes 1.4

45 minutes 1.3

60 minutes 1.2

NGT capacity： kVAS 80.436.107.70

==

Rating：50 kVA

3 Calculation for generator neutral fault current:

Generator fault capacitive current:



TPP, Yamunanagar


A

cUI ec

52.510507.0314203

1033

3

=××××=

×=−

−ω

Generator fault current ：

AII c

78.752.522

=×=≈

ANNEXURE II Date sheet for generator



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21.0 ELECTRICAL

21.1 GENERATOR MAIN

PARAMETERS

21.1.1 Manufacturer’s Name:

a) Make of Generator

b) Type/Model No.

c) AppIicable standards

21.1.2 Maximum continuous

output(MCR)at rated hydrogen

pressure and specified cooling

water temperature

21.1.3 Rated stator voltage

21.1.4 Rated stator current

:

:

:

:(MVA)

:(kV)

:(Amps)

Shanghai Turbine Generator Co,

Limited

Water-Hydrogen lnner-cooled/

QFSN-300-2

lEC34-1,IEC34-3,IEC34

GB/T7064,GB755

370.5

20

10189

1



TPP, Yamunanagar


21.1.5 Rated frequency and

speed

21.1.6 Rated power factor

21.1.7 Field current at MCR

21.0.8 Field voltage at MCR

21.1.9 Maximum continuous

permissible variation

range in:

a) Rated stator voltage

b) Rated frequency

c) Combined permissible

variation of voltage

and frequency

21.1.10 Number of:

a) phases

:(Hz),(RPM)

:(Lag)

:(Amps)

:(Volts)

:(%)

:(%)

:(%)

50，3000

0.85

2601

312

±5

-5 to +3

As per IEC34-1 section 6.3

3



TPP, Yamunanagar


b) parallel paths/phase

c) Line side terminals

brought out

:

:

2

3

d) Neutral side

terminals brought out

21.1.11 Maximum temperature

of

a) Stator winding by RTD

b) Rotor windings

21.1.12 Generator efficiency at

rated power and power factor

21.1.13 Short circuit ratio(SCR)

corresponding to

maximum capability

21.1.14 Permissible tolerance in SCR

:

:( )

:

:

:(%)

:

:(±%)

3

＜85

＜110

98.8%(guaranteed value with no

negative tolerance)

98.93%(designed value)

0.6

According to IEC 60034-3 (+/-15%)

1

1

11



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21.1.15 Regulation at

a) Unity power factor

b) 0.85 power factor

lagging

21.1.16 Rated hydrogen

pressure

21.1.17 lnsulation class

a) Stator winding

b) Rotor winding

21.1.18 Basic impulse insulation

withstand voltage of

stator winding with

respect to earth (for standard

wave shape of 1.2/50 micro

sec.)

21.1.19 Symmetrical r.m.s

short circuit current with

generator isolated:

a) 3-phase

:

:

:(kg/cm2)

: (kPa)

:

:

:(kV peak)

:

(kA)

Shall be provided during

detailed engineering



3.16/(310)

F

F

kVU N 5.72)12(225.1 =+××

Initial value Sustained value

69 15.5

1

1



TPP, Yamunanagar


b) Single phase to earth

21.0.20 3-phase short circuit

Withstand time

:(kA)

:(sec.)

80

2.5

21.1.21 permissible unbalanced

load capability subject to rated

current not being exceeded in any

phase:

a) Maximum continuous

negative sequence current l2

b) Minimum value of l2t

for transient

operation under

system fault

conditions(where’s

in seconds)

21.1.22 Maximum permissible

inductive loading at

zero PF

21.1.23 Maximum permissible

capacitive loading for

stability at rated voltage

and zero power factor

:(p.u.)

:(sec.)

:(MVAR)

:(MVAR)

10%

10

270

154

1

1



TPP, Yamunanagar


21.1.24 Generator parameters

at rated kV and MVA

a) Direct axis

synchronous

reactance Xd

b) Direct axis transient

reactance X’d

c) Direct axis sub-

transient reactance X”d

d) Effective winding

capacitance to earth:

i) Per phase

ii) All phases connected

together

e) Effective surge

I impedance to neutral

per phase

21.1.25 Maximum temperature of

H2 With the secondary

cooling water inlet

temperature as specified

21.1.26 Generator losses,

:

:(p.u.)

: (p.u.)

:(p.u.)

:(Microfarad)

:(Microfarad)

:(Ohms)

:()

Unsaturated Saturated

180%

22.9% 20.2%

17.4% 16%

0.209

0.627

Shall be provide during


≤46

1



TPP, Yamunanagar


also indicate

where one loss component is

included in the another one

give curves various losses Vs.

Load as above at different

hydrogen pressures：

a) Stator core loss

b) Rotor copper loss at full

load(including excitor)

c) Stator copper loss at full

load

d) Stray load loss

e) Friction and windage loss

f) Mechanical losses

included bearing losses

g) tolerance on above losses

21.1.27 number of

temperature Monitoring

points in:

a) stator core

b) stator winding

:(kW)

:(kW)

:(kW)

:(kW)

:(kW)

:(kW)

:(+%),(-%)

:

:

435

904

816

425

205

407

+10%

10(yoke)+10(teeth)

54



TPP, Yamunanagar


c) generator bearings

and excitor

21.2 ADDLTLONAL DATA

21.2.1Permissible overload and

duration

21.2.2 Surge capacitor

requirement for the generator

21.2.3 Complete description of

stator core monitoring system

for the generator enclosed

21.2.4 permissible volts/Hz Vs

time characteristic of the

generator enclosed

21.2.5 a) Type of excitation

system

b) Detailed write-up/

literature for the

excitation system,

enclosed

c) Block schematic

diagram of excitation

system enclosed

:(p.u)& (sec.)

:(µf)

: (Yes/No)

:(Yes/No)

:(Yes/No)

:(Yes/No)

2+1

1.05(long duration)

0.25



Yes

Brushless excitor

Yes



1

1

1



TPP, Yamunanagar


21.2.6 a)Type of voltage regulator

b) Description of

voltage regulator

21.2.7 Type of cooling for

a) Stator winding

b) Stator core

c) Rotor

21.2.8 Transient rise of voltage

on sudden rejection of full

load at rated power factor

a) with AVR

b)without AVR

21.2.9 Acceleration time

21.2.10 lnertia constant H

a) Generator& Exciter

b) Complete turbine

:(Yes/No)

:(Yes/No)

:

:(Yes/No)

:

:

: (p.u)

: (p.u)

: (sec)

: (kW-sec/kVA)

:

DAVR

microprocessor-based, with

dual channel, mutually

redundant, automatic following

and automatic changeovers,

digital type voltage regulator

Water

Hydrogen

Hydrogen

1.1

1.31



1.14


1



TPP, Yamunanagar


generator unit

21.2.11 Fly wheel moment of

inertia of generator +

exciter

21.2.12 Hydrogen coolers:

a) Number of cooler

section

b) Maximum

continuous rating of

generatlr with one

section cooler out of

operation

c) Material of -

i) Tubes

ii) Fins

iii) Tube plate

iv) Water boxes

d) Quantity of cooling

water required/cooler

e) Rated cooling water

pressure

f) Pressure drop

(Kg-)

:

: (MVA)

:

:

:

:

:

:(m3 /hr)

:

(kPa)

: (m.w.c)


32700

8 (4 coolers with 8 sections)

90% (with one section of 8

out of service)

Bfe10-1-1

copper

Bronze

Steel

440 (110 per cooler)

600(max)

56kPa

1

1

1

1

1



TPP, Yamunanagar


across cooler on

water side

g) Rated cooling water

temperature at

cooler inlet

21.2.13 Degree of protection as

per IEC 34-5

21.3.4 Current Transformers

a) Make & Country of

the manufacturer

b) Type

c) Reference standard

d) Class of insulation

e) Rated short time

thermal current for

three(3)sec

f) Momentary current

21.3 Brushless exciter

technical data

: ()

:

:

:

:

:

:

: (kA)

: (kAp)

≤38

IP-54

Yes

Shanghai instrument transformer

works

Bushing CT

GB1208-997(epv IEC44-1,1996)

Insulation class F, Temperature

rise limited to class B





1

1

1

1

1

1

1



TPP, Yamunanagar


21.3.1Exciter DC Rating

rated capacity

rated voltage

rated current

efficiency

21.3.2Exciter AC Rating

rated capacity

rated power factor

rated frequency

rated voltage

rated current

parallel No.

phase No.

rated speed

Pole No.

Cooling air temp.

: (kW)

: (V)

: (A)

: (kVA/kW)

: (Hz)

: (V)

: (A)

: (r/min)

1650

475

3474

90%

1883/1695

0.9

250

403

2698

5Y

3

3000

10



TPP, Yamunanagar


Rated/Max

Air cooler capacity

21.3.3Exciter Parameter

1.Resistance

Armature winding

resistance(75)

Field winding resistance(75)

2.Field winding inductance

3.Reactance(Unsaturated)

Direct axis sub-transient

reactance X”d

Direct axis transient reactance

X’d

Direct axis synchronous

reactance Xd

Quadrature axis sub-transient

reactance X”q

Quadrature axis transient

reactance X’q

Quadrature axis synchronous

reactance Xq

Negative phase-sequence

: (/)

kW)

: (Ω/ph)

: (Ω)

: (H)

45/50

2x125

0.35x10-3

0.0657

0.108

13.6%

13.6%

60.3%

35.7%

35.7%

35.7%

16.6%



TPP, Yamunanagar


reactance X2

Zero phase-sequence

reactance X0

4.Time constant

Transient direct axis open

circuit T’do

Transient direct axis short

circuit T’d

5.High initial voltage response

6.Ceiling voltage

7.Critical speed

1st

2nd

8.Rotor flywheel moment GD2

21.3.4 Rectifier circuit

Type

Model of diode

Rating of diode

: (s)

: (s)

: (r/min)

: (r/min)

: (t-m2)

: (A)

7.35%

1.64s

0.37s

≤0.1s

2 times

2450

5200

1.1

Single wheel 3-phase full wave

rectifier design ,A 3-phase bridge

with 8 diodes connected in

parallel each phase

R6L-40 disk type

400



TPP, Yamunanagar


Diode reverse voltage

Fuse rated current

Fuse rated voltage

Fuse resistance(25)

Capacitor rating

Capacitor fuse rated current

21.3.5 Permanent magnet pilot

exciter

Rated capacity

Rated power factor

Rated frequency

Rated voltage

Rated current

Parallel

Phase No.

Rated speed

: (V)

: (A)

: (V)

: (Ω)

: (μF)

: (A)

: (kVA/kW)

: (Hz)

: (V)

: (A)

: (r/min)

2000

670

750

(0.102~0.119)X10-3

0.3

15

33.24/31.6

0.95

350

95

202

2Y

3

3000



TPP, Yamunanagar


Pole No.

Permanent magnet material

21.3.6Air cooler

Exciter cooling air flow

Total water flow required

Max. inlet water temp. of air

cooler

21.3.7Bearing

Bearing type

Bearing diameter

Bearing length

Bearing oil flow required

: (m3/s)

: (t/h)

: ()

: (mm)

: (mm)

: (l/min)

14

AINiCo5-7

2x4.6

2x45

35

Tilt-pad

228.8

102

25



TPP, Yamunanagar


ANNEXURE III Generator capability curve



TPP, Yamunanagar


ANNEXURE IV Generator overfluxing capability curve



TPP, Yamunanagar


ANNEXURE V Generator saturation curve

Line V

oltage (kV)

Line C

urrent (A)



TPP, Yamunanagar


ANNEXURE VI Generator vee curve

Leading

Lagging



TPP, Yamunanagar


ANNEXURE VII Exciter characteristic curve

Date post:	12-Apr-2015
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