DBR BTG Electrical

HARYANA POWER GENERATION CORPORATION PANCHKULA, HARYANA DESEIN PRIVATE LIMITED CONSULTING ENGINEER  NEW DELHI

CENTRAL ELECTRICITY AUTHORITY

SEWA BHAWAN, R K PURAM, NEW DELHI DCR Thermal Power Project (2 x 300 MW), Yamunanagar DESIGN BASIS REPORT FOR BTG ELECTRICAL SYSTEM DOCUMENT NO. 50-F248C-D01-01 50-F248C-D01-01

RELIANCE ENERGY LIMITED REL TOWER, A-2, SECTOR-24 NOIDA (U NOIDA (U.P .P)) – 2013 201301 01 DEVELOPMENT CONSULTANTS PRIVATE LIMITED CONSULTING ENGINEERS 24B PARK STREET, KOLKATA - 700 016, INDIA

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

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

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar  Yamunanagar 

DOCUMENT CONTROL SHEET PROJECT

:

DCR THERMAL POWER PROJECT 2 X 300 MW UNITS

CLIENT

:

DOCUMENT TITLE

:

DESIGN BASIS REPORT FOR BTG ELECTRICAL SYSTEM

DOCUMENT NO.

:

50-F248C-D01-01

REV. NO.

:

1

HARYANA POWER GENERATION CORPORATION

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 Road,chengdu,China DOCUMENT NO.: 50-F248C-D01-01 50-F248C-D01-01

Page 1

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar  Yamunanagar 

DOCUMENT CONTROL SHEET PROJECT

:

DCR THERMAL POWER PROJECT 2 X 300 MW UNITS

CLIENT

:

DOCUMENT TITLE

:

DESIGN BASIS REPORT FOR BTG ELECTRICAL SYSTEM

DOCUMENT NO.

:

50-F248C-D01-01

REV. NO.

:

1

HARYANA POWER GENERATION CORPORATION

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 Road,chengdu,China DOCUMENT NO.: 50-F248C-D01-01 50-F248C-D01-01

Page 1

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar  Yamunanagar 

CONTENTS CLAUSE NO.

DESCRIPTION

PAGE No

1 General...................... General.................................... ............................ ............................ ............................. ....................... ........ 1 1.1 Intent of Design Basic Report............................ Report........................................... ..................... ...... 1 1.2 Scope of Design ............................. ........................................... ............................. ........................... ............ 1 1.3 Design Design Philosophy............. Philosophy............................ ............................. ............................. ......................... .......... 1 2 Design criteria criteria of equipment equipment and and system system ............................. ................................... ...... 3 2.1 Generator Generator system.............. system ............................ ............................. ............................. ......................... ........... 3 2.2 Generator Generator surge surge protection protection system .............................. ....................................... ......... 21 2.3 Generator Generator neutral neutral grounding grounding system system.............. .............................. ....................... ....... 22 2.4 Generator Generator Metering Metering ............................ .......................................... ............................. ..................... ...... 23 2.5 Synchronizati Synchronization on ............................. ............................................ ............................. ......................... ........... 24 3 Equipment Equipment description description............... ............................. ............................. ............................. .................. .... 24 3.1 Generator Generator system.............. system ............................ ............................. ............................. ....................... ......... 24 3.2 Generator Generator surge surge protection protection system .............................. ....................................... ......... 26 3.3 Generator Generator neutral neutral grounding grounding system system.............. .............................. ....................... ....... 27 3.4 Excitation Excitation system ............................. ........................................... ............................ ....................... ......... 28 3.5 Generator Generator Protectio Protection n Relay Relay ............................ .......................................... ....................... ......... 30 3.6 Generator Generator metering metering panel .............................. ............................................. ....................... ........ 33 3.7 Generator Generator fault recorder recorder panel panel ............................. ........................................... ................. ... 33 4 Generator control & operation philosophy Records.................. Records........ .......... 34 5 Main Equipments Equipments list ........................... .......................................... ............................. ...................... ........ 34

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

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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

DOCUMENT NO.: 50-F248C-D01-01

Page 3

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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:

DOCUMENT NO.: 50-F248C-D01-01

Page 1

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

Design Basis Report for  BTG Electrical System

 Average Grade Level

270.0Meter (above MSL) (+) 50℃ (Max.) (-) 0.6℃ (Min.)

Design Ambient Air Temperature

150kg/m2

Wind Pressure 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

 AC motors rated above 175 kW

Voltage

6600V±10%

No. of phases

Fault Level

Grounding

3Ph, 50 Hz.

40KA for 1

Non-effectively

(+)/(-) 5%

Sec

earthed

3Ph, 50 Hz.

50KA for 1

Effectively

(+)/(-) 5%

Sec

earthed

2 wire DC

25KA

Unearthed

2 wire DC

25KA

Unearthed

1Ph， 50 Hz,

50KA for 1

Effectively

(+)/(-) 5%

Sec

earthed

1Ph， 50 Hz,

50KA for 1

Effectively

(+)/(-) 5%

Sec

earthed

3Ph,50 Hz,

50KA for 1

Effectively

(+)/(-) 5%

Sec

earthed

3Ph， 50 Hz,

50KA for 1

Effectively

(+)/(-) 5%

Sec

earthed

& frequency

 AC motors rated up to and including 175 kW, power  receptacles and three phase AC

415V±10%

loads DC Motors Control, indication & protection circuits for HT/LT circuit breakers and emergency lighting Control & indication for contactor  operated 415 V motors Space heater(no more than 1.2kW) for motors and cubicles Space heater(more than 1.2kW) for motors Interior lighting, receptacles and general power 

220 V +10% to -15% 220 V +10% to -15%

110V±10%

240V±10%

415V±10%

240V±10%

DOCUMENT NO.: 50-F248C-D01-01

Page 2

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

2 Design criteria of equipment equipment and system 2.1 Generator system 2.1.1 General description of generator  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 DOCUMENT NO.: 50-F248C-D01-01 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 singlestage axial blowers, mounted mounted on both both ends of 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. cooled. The hydrogen hydrogen is cooled by the hydrogen-to-water 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

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

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 directly with de - ionized water. 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

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

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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  DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 micapaper 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. DOCUMENT NO.: 50-F248C-D01-01

Page 8

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 endturns 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

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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.

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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,

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

creep

resistant,

silver-bearing

copper

and

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 creepresistant 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

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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  DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 r eturns 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.

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 arr angement. 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

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram 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 generator 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. DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram 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

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram 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：

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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:

20 0.11 0.11 0.11 / / / kV  ,1set 3 3 3 3

B

PT’s:

20 0.11 0.11 0.11 / / / kV  ,1set 3 3 3 3

C

PT’s:

20 0.11 0.11 0.11 / / / kV  ,1set 3 3 3 3

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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram 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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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, DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram 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)

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

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 DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram 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

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP,  Yamunanagar 

Quantity

No.

Name

Type & specification

Unit

Remark 1＃

1.

1.1

1.1.1

2＃

total

Generator system Generator part）

equipment(electrical

Bushing CT

Supplied by generator  manufacturer 

1.1.2

Terminal box for connection the IPBD to generator 

1.2

Rotating brushless excitation system

1.3

PT & LA cabinet

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

set

1

1

set

1

1

2

Supplied by REL

2 1(2)0AAA01~03

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Design Basis Report for BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP,  Yamunanagar 

Quantity

No.

Name

Type & specification

Unit

Remark 1＃

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

1.4

Neutral point grounding transformer cabinet

2＃

total

set

9

9

18

PT：JDZJ－20

20 0.11 0.11 0.11 / / / kV  3 3 3 3

set

3

3

6

PT：JDZJ－20

20 0.11 0.11 0.11 / / / kV  3 3 3 3

set

3

3

6

PT：JDZJ－20

20 0.11 0.11 0.11 / / / kV  3 3 3 3

set

3

3

6

LA：Y5W1－24/56.2

set

3

3

6

Capacitor ：0.25μf 

set

3

3

6

including ： dye-type single phase transformer: 50kVA 20/0.24Kv

set

1

1

2

1(2)0MK01

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

DOCUMENT NO.: 50-F248C-D01-01

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Design Basis Report for BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP,  Yamunanagar 

Quantity

No.

Name

Type & specification

Unit

Remark 1＃

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

1.4

Neutral point grounding transformer cabinet

2＃

total

set

9

9

18

PT：JDZJ－20

20 0.11 0.11 0.11 / / / kV  3 3 3 3

set

3

3

6

PT：JDZJ－20

20 0.11 0.11 0.11 / / / kV  3 3 3 3

set

3

3

6

PT：JDZJ－20

20 0.11 0.11 0.11 / / / kV  3 3 3 3

set

3

3

6

LA：Y5W1－24/56.2

set

3

3

6

Capacitor ：0.25μf 

set

3

3

6

including ： dye-type single phase transformer: 50kVA 20/0.24Kv

set

1

1

2

1(2)0MK01

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

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DOCUMENT NO.: 50-F248C-D01-01

Design Basis Report for BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP,  Yamunanagar 

Quantity

No.

Name

Type & specification

Unit

Remark 1＃

2＃

total

CT： 0.5 10/5A Single phase disconnector ：GN2－20/400 400A 2

Excitation system

2.1

Exciter 

2.2

Permanent exciter 

2.3

Regulator panel

Size: 2260(H)x800(W)x800(W)

2.4

Converter and suppression panel

Size: 2260(H)x800(W)x800(W)

2.5

Field grounding panel

2.6

Manual excitation control panel

Size: 2360(H)x800(W)x800(W)

2.7

Manual excitation adjust panel

Size: 2360(H)x800(W)x800(W)

1650kW, 475V, 3474A, exciter efficiency:90%

magnet

pilot

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

detector  Size: 2260(H)x800(W)x800(W)

DOCUMENT NO.: 50-F248C-D01-01

set

1

1

2

set

1

1

2

set

1

1

2

piece

1

1

2

piece

1

1

2

piece

1

1

2

piece

1

1

2

piece

1

1

2

Page 37

Design Basis Report for BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP,  Yamunanagar 

Quantity

No.

Name

Type & specification

Unit

Remark 1＃

2＃

total

CT： 0.5 10/5A Single phase disconnector ：GN2－20/400 400A 2

Excitation system

2.1

Exciter 

2.2

Permanent exciter 

2.3

Regulator panel

Size: 2260(H)x800(W)x800(W)

2.4

Converter and suppression panel

Size: 2260(H)x800(W)x800(W)

2.5

Field grounding panel

2.6

Manual excitation control panel

Size: 2360(H)x800(W)x800(W)

2.7

Manual excitation adjust panel

Size: 2360(H)x800(W)x800(W)

1650kW, 475V, 3474A, exciter efficiency:90%

magnet

pilot

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

detector  Size: 2260(H)x800(W)x800(W)

set

1

1

2

set

1

1

2

set

1

1

2

piece

1

1

2

piece

1

1

2

piece

1

1

2

piece

1

1

2

piece

1

1

2

Page 37

DOCUMENT NO.: 50-F248C-D01-01

Design Basis Report for BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP,  Yamunanagar 

Quantity

No.

Name

Type & specification

Unit

Remark 1＃

2.8

2＃

total

 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 panel

piece

1

1

2

6

Generator synchronization panel

piece

1

1

2

7

Terminal box

piece

2

2

4

8

DC drive & control box

piece

5

5

10

9

Control cable

km

5

5

10

fault

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

DOCUMENT NO.: 50-F248C-D01-01

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

Size: 1600(H)x800(W)x600(W)

Page 38

Design Basis Report for BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP,  Yamunanagar 

Quantity

No.

Name

Type & specification

Unit

Remark 1＃

2.8

2＃

total

 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 panel

piece

1

1

2

6

Generator synchronization panel

piece

1

1

2

7

Terminal box

piece

2

2

4

8

DC drive & control box

piece

5

5

10

9

Control cable

km

5

5

10

fault

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

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

Size: 1600(H)x800(W)x600(W)

Page 38

DOCUMENT NO.: 50-F248C-D01-01

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

Annexure I: Sizing calculation for generator neutral grounding system

1 Base data

（1）Capacitance of generator:

C 1 = 0.209  f  /  phase

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

provided by REL):

C 2 = 0.036  f  /  phase

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

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

Annexure I: Sizing calculation for generator neutral grounding system

1 Base data

（1）Capacitance of generator:

C 1 = 0.209  f  /  phase

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

provided by REL):

C 2 = 0.036  f  /  phase

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

C 3 = 0.005µ  f  /  phase

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

C 4 = 0.002  f  /  phase

（5）Capacitance of Surge capacitor 

C  5 = 0 . 25

 f   /  phase

2 Sizing calculation

Each phase total capacitance of the generator and the equipments connected

DOCUMENT NO.: 50-F248C-D01-01

Page 39

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

with the generator 

∑ C n = 0.25 + 0.209 + 0.036 + 0.005 × 2 + 0.002 = 0.507 µ  f  /  phase

Three phase capacitance to ground:  X cg  =

1 3

×

1 2π  f  ∑ C n

= 2093.83Ω

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

 R ' =

 X cg  1 .1

=

2093 .83 1.1

Basis for the factor 1.1:The safety

= 1903 .48Ω

factor is according to the Chinese

Electrical Design reference book. Ratio of neutral ground transformer ： N  =

20 × 10 240

3

= 83.33

The resistance of the neutral grounding transformer secondary side:

 R =

 R ' 2

=

1903.48 83.332

= 0.274Ω

The current of neutral grounding transformer secondary side:

 I r  =

U 2 3 × R

=

240 3 × 0.274

= 506 A

The rating of the resistance:

DOCUMENT NO.: 50-F248C-D01-01

Page 40

Design Basis Report for  BTG Electrical System

 P r  =

U 22 3 R

=

2402 3 × 0.274

× 10

−3

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

= 70.07kW 

NGT capacity:

S  ≥ P r 

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： S  =

70.07 1.6

= 43.80kVA

Rating：50 kVA

3 Calculation for generator neutral fault current:

Generator fault capacitive current:

DOCUMENT NO.: 50-F248C-D01-01

Page 41

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

 I c = 3U eω c × 10−3 =

3 × 20 × 314 × 0.507 × 10 − 3

= 5.52 A

Generator fault current ：

 I  ≈ 2 I c =

2 × 5.52

= 7.78 A

ANNEXURE II Date sheet for generator  DOCUMENT NO.: 50-F248C-D01-01

Page 42

Design Basis Report for  BTG Electrical System

21.0

ELECTRICAL

21.1

GENERATOR MAIN

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

PARAMETERS

21.1.1 Manufacturer’s Name:

a) Make of Generator 

:

Shanghai Turbine Generator Co, Limited

b) Type/Model No.

:

Water-Hydrogen lnner-cooled/ QFSN-300-2

c) AppIicable standards

:

lEC34-1,IEC34-3,IEC34 GB/T7064,GB755

:(MVA)

370.5

21.1.3 Rated stator voltage

:(kV)

20

21.1.4 Rated stator current

:(Amps)

10189

21.1.2 Maximum continuous output(MCR)at rated hydrogen pressure and specified cooling water temperature

DOCUMENT NO.: 50-F248C-D01-01

Page 43

Design Basis Report for  BTG Electrical System

21.1.5 Rated frequency and

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

:(Hz),(RPM)

50，3000

21.1.6 Rated power factor 

:(Lag)

0.85

21.1.7 Field current at MCR

:(Amps)

2601

21.0.8 Field voltage at MCR

:(Volts)

312

a) Rated stator voltage

:(%)

±5

b) Rated frequency

:(%)

-5 to +3

c) Combined permissible

:(%)

 As per IEC34-1 section 6.3

speed

21.1.9 Maximum continuous

permissible variation range in:

variation of voltage and frequency

21.1.10 Number of: a) phases

DOCUMENT NO.: 50-F248C-D01-01

3

Page 44

Design Basis Report for  BTG Electrical System

b) parallel paths/phase

:

2

c) Line side terminals

:

3

:

3

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

brought out

d) Neutral side terminals brought out

21.1.11 Maximum temperature :(℃ ) of  a) Stator winding by RTD

:

＜85

b) Rotor windings

:

＜110

21.1.12 Generator efficiency at :(%) rated power and power factor 

98.8%(guaranteed value with no negative tolerance) 98.93%(designed value)

21.1.13 Short circuit ratio(SCR) :

0.6

corresponding to maximum capability

21.1.14 Permissible tolerance :(±%) in SCR

DOCUMENT NO.: 50-F248C-D01-01

 According to IEC 60034-3 (+/-15%)

Page 45

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

21.1.15 Regulation at

a) Unity power factor 

:

Shall be provided during detailed engineering

b) 0.85 power factor 

:

detailed engineering

lagging

21.1.16

Rated

Shall be provided during

hydrogen :(kg/cm2)

pressure

: (kPa)

21.1.17 lnsulation class

:

3.16/(310)

F

a) Stator winding

b) Rotor winding

:

21.1.18 Basic impulse insulation :(kV peak)

F

1.25 × 2 × ( 2U  N  + 1) = 72.5kV 

withstand voltage of  stator winding with respect to earth (for standard wave shape of 1.2/50 micro sec.)

21.1.19 short

Symmetrical circuit

current

r.m.s

Initial value Sustained value

with

generator isolated: : a) 3-phase

(kA)

DOCUMENT NO.: 50-F248C-D01-01

69

15.5

Page 46

Design Basis Report for  BTG Electrical System

b) Single phase to earth

:(kA)

80

21.0.20 3-phase short circuit

:(sec.)

2.5

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

Withstand time

21.1.21 permissible unbalanced load capability subject to rated current not being exceeded in any phase:

a) Maximum continuous

:(p.u.)

10%

:(sec.)

10

:(MVAR)

270

:(MVAR)

154

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 

DOCUMENT NO.: 50-F248C-D01-01

Page 47

Design Basis Report for  BTG Electrical System

21.1.24 Generator parameters :

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

Unsaturated

Saturated

at rated kV and MVA

a) Direct axis

:(p.u.)

180%

synchronous reactance Xd

b) Direct axis transient

: (p.u.)

22.9%

20.2%

:(p.u.)

17.4%

16%

i) Per phase

:(Microfarad)

0.209

ii) All phases connected

:(Microfarad)

0.627

:(Ohms)

Shall be provide during

reactance X’d

c) Direct axis subtransient reactance X”d

d) Effective winding capacitance to earth:

together 

e) Effective surge I

impedance to neutral

detailed engineering

per phase

21.1.25 Maximum temperature of  :(℃)

≤46

H2 With the secondary cooling water inlet temperature as specified 21.1.26

Generator losses,

DOCUMENT NO.: 50-F248C-D01-01

Page 48

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram 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： :(kW)

435

full :(kW)

904

c) Stator copper loss at full :(kW)

816

a) Stator core loss

b) Rotor copper loss at load(including excitor)

load

d) Stray load loss

:(kW)

425

e) Friction and windage loss

:(kW)

205

f) Mechanical losses

:(kW)

407

:(+%),(-%)

+10%

a) stator core

:

10(yoke)+10(teeth)

b) stator winding

:

54

included bearing losses

g) tolerance on above losses

21.1.27

number

temperature

of 

Monitoring

points in:

DOCUMENT NO.: 50-F248C-D01-01

Page 49

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

2+1

c) generator bearings and excitor 

21.2 ADDLTLONAL DATA

21.2.1Permissible overload and

:(p.u)& (sec.)

1.05(long duration)

duration

21.2.2

Surge

capacitor  :(µf)

0.25

requirement for the generator 

21.2.3 Complete description of 

: (Yes/No)

Shall be provided during detailed engineering

stator core monitoring system for the generator enclosed

21.2.4 permissible volts/Hz Vs

:(Yes/No)

Yes

time characteristic of the generator enclosed

21.2.5 a)

Brushless excitor 

Type of excitation

system b) Detailed write-up/

:(Yes/No)

Yes

:(Yes/No)

Shall be provided during

literature for the excitation system, enclosed

c) Block schematic diagram of excitation

detailed engineering

system enclosed DOCUMENT NO.: 50-F248C-D01-01

Page 50

Design Basis Report for  BTG Electrical System

21.2.6 a)Type of voltage regulator  :(Yes/No)

b) Description of  voltage regulator 

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

DAVR

:(Yes/No)

microprocessor-based, with

:

dual channel, mutually redundant, automatic following and automatic changeovers, digital type voltage regulator 

21.2.7 Type of cooling for 

a) Stator winding

b) Stator core

:(Yes/No)

Water 

:

Hydrogen

: Hydrogen

c) Rotor 

21.2.8 Transient rise of voltage on sudden rejection of full load at rated power factor 

a) with AVR

: (p.u)

1.1

b)without AVR

: (p.u)

1.31

21.2.9 Acceleration time

: (sec)

Shall be provided during detailed engineering

21.2.10 lnertia constant H

: (kW-sec/kVA)

a) Generator& Exciter 

:

b) Complete turbine DOCUMENT NO.: 50-F248C-D01-01

1.14 Shall be provided during Page 51

Design Basis Report for  BTG Electrical System

generator unit

21.2.11 Fly wheel moment of 

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

detailed engineering

(Kg-㎡)

32700

:

8 (4 coolers with 8 sections)

: (MVA)

90% (with one section of 8

inertia of generator + exciter 

21.2.12 Hydrogen coolers:

a) Number of cooler  section

b) Maximum

out of service)

continuous rating of  generatlr with one section cooler out of  operation

c) Material of -

:

i) Tubes

:

Bfe10-1-1

ii) Fins

:

copper 

plate

:

Bronze

iv) Water boxes

:

Steel

d) Quantity of cooling

:(m3 /hr)

440 (110 per cooler)

iii) Tube

water required/cooler  : e) Rated cooling water 

(kPa)

600(max)

pressure

f) Pressure drop DOCUMENT NO.: 50-F248C-D01-01

: (m.w.c)

56kPa Page 52

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

across cooler on water side

g) Rated cooling water 

: (℃)

≤38

:

IP-54

21.3.4 Current Transformers

:

Yes

a) Make & Country of 

:

Shanghai instrument transformer 

temperature at cooler inlet

21.2.13 Degree of protection as per IEC 34-5

the manufacturer 

works

b) Type

:

Bushing CT

c) Reference standard

:

GB1208-997(epv IEC44-1,1996)

d) Class of insulation

:

Insulation class F, Temperature rise limited to class B

e) Rated short time

Shall be provided during

thermal current for 

detailed engineering

three(3)sec

f) Momentary current

: (kA)

Shall be provided during detailed engineering

21.3

Brushless

exciter 

technical data : (kAp) DOCUMENT NO.: 50-F248C-D01-01

Page 53

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

21.3.1Exciter DC Rating

rated capacity

: (kW)

1650

rated voltage

: (V)

475

rated current

: (A)

3474

efficiency

90%

21.3.2Exciter AC Rating rated capacity

: (kVA/kW)

rated power factor 

1883/1695

0.9

rated frequency

: (Hz)

250

rated voltage

: (V)

403

rated current

: (A)

2698

parallel No.

5Y

phase No.

3

rated speed

Pole No.

: (r/min)

3000

10

Cooling air temp. DOCUMENT NO.: 50-F248C-D01-01

Page 54

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

Rated/Max

: (℃/℃)

45/50

 Air cooler capacity

kW)

2x125

21.3.3Exciter Parameter 

1.Resistance

 Armature

winding : (Ω/ph)

0.35x10-3

resistance(75℃)

Field winding resistance(75℃)

: (Ω)

0.0657

2.Field winding inductance

: (H)

0.108

3.Reactance(Unsaturated)

Direct

axis

sub-transient

13.6%

Direct axis transient reactance

13.6%

reactance X”d ’

Xd synchronous

60.3%

Quadrature axis sub-transient

35.7%

Direct

axis

reactance Xd reactance X”q transient

35.7%

Quadrature axis synchronous

35.7%

Quadrature

axis

reactance X’q reactance Xq Negative

phase-sequence

DOCUMENT NO.: 50-F248C-D01-01

16.6% Page 55

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

Design Basis Report for  BTG Electrical System

reactance X2 Zero

phase-sequence

7.35%

reactance X0 4.Time constant

Transient

direct

axis

open : (s)

1.64s

direct

axis

short : (s)

0.37s

circuit T’do Transient circuit T’d 5.High initial voltage response

≤0.1s

6.Ceiling voltage

2 times

7.Critical speed

1st

: (r/min)

2450

2nd

: (r/min)

5200

8.Rotor flywheel moment GD2

: (t-m2)

1.1

21.3.4 Rectifier circuit

Single wheel 3-phase full wave

Type

rectifier design ,A 3-phase bridge with 8 diodes connected in parallel each phase

Model of diode

Rating of diode

DOCUMENT NO.: 50-F248C-D01-01

R6L-40 disk type : (A)

400

Page 56

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

Diode reverse voltage

: (V)

2000

Fuse rated current

: (A)

670

Fuse rated voltage

: (V)

750

Fuse resistance(25℃)

: (Ω)

(0.102~0.119)X10-3

Capacitor rating

: (μF)

0.3

Capacitor fuse rated current

: (A)

15

: (kVA/kW)

33.24/31.6

21.3.5 Permanent magnet pilot exciter 

Rated capacity

0.95

Rated power factor 

Rated frequency

: (Hz)

350

Rated voltage

: (V)

95

Rated current

: (A)

202

Parallel

2Y

Phase No.

3

Rated speed DOCUMENT NO.: 50-F248C-D01-01

: (r/min)

3000 Page 57

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

Pole No.

14

Permanent magnet material

 AINiCo5-7

21.3.6Air cooler 

Exciter cooling air flow

: (m3/s)

2x4.6

Total water flow required

: (t/h)

2x45

Max. inlet water temp. of air  : (℃)

35

cooler 

21.3.7Bearing

Bearing type

Tilt-pad

Bearing diameter 

: (mm)

228.8

Bearing length

: (mm)

102

Bearing oil flow required

: (l/min)

25

DOCUMENT NO.: 50-F248C-D01-01

Page 58

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

ANNEXURE III Generator capability curve

DOCUMENT NO.: 50-F248C-D01-01

Page 59

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

ANNEXURE IV Generator overfluxing capability curve

DOCUMENT NO.: 50-F248C-D01-01

Page 60

Design Basis Report for  BTG Electrical System

ANNEXURE V Generator saturation curve

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

L i   n  e   V  o l    t    a  g  e   (   k   V  )  

L i   n  e   C  u r  r   e  n  t    (   A  )  

DOCUMENT NO.: 50-F248C-D01-01

Page 61

Design Basis Report for  BTG Electrical System

HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar 

ANNEXURE VI Generator vee curve

L  e   a  d  i   n  g

L  a  g  g i   n  g

DOCUMENT NO.: 50-F248C-D01-01

Page 62