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Transcript of 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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 2
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 3
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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
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
1
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:
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 2
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 3
1
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 4
1
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 5
1
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 6
1
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 7
1
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 8
1
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.
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 9
1
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 10
1
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.
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 11
1
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,
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 12
1
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 13
1
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 14
1
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 15
1
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 16
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 17
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 18
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 19
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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.
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 20
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 21
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 22
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.
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 23
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 24
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 25
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 26
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:
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 27
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 28
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 29
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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,
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 30
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)
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 31
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 32
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 33
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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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 34
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
DOCUMENT NO.: 50-F248C-D01-01 Page 35
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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
Design Basis Report for BTG Electrical System HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 36
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Quantity No. Name Type & specification Unit
1# 2# total Remark
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
Design Basis Report for BTG Electrical System HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 37
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Quantity No. Name Type & specification Unit
1# 2# total Remark
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
Design Basis Report for BTG Electrical System HPGC : 2 x 300 MW Deenbandhu Chhotu Ram TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 38
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1
1
Quantity No. Name Type & specification Unit
1# 2# total Remark
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 39
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
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DOCUMENT NO.: 50-F248C-D01-01 Page 40
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:
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
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DOCUMENT NO.: 50-F248C-D01-01 Page 41
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:
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
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DOCUMENT NO.: 50-F248C-D01-01 Page 42
A
cUI ec
52.510507.0314203
1033
3
=××××=
×=−
−ω
Generator fault current :
AII c
78.752.522
=×=≈
ANNEXURE II Date sheet for generator
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
TPP, Yamunanagar
DOCUMENT NO.: 50-F248C-D01-01 Page 43
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
Design Basis Report for BTG Electrical System
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DOCUMENT NO.: 50-F248C-D01-01 Page 44
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
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
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DOCUMENT NO.: 50-F248C-D01-01 Page 45
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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DOCUMENT NO.: 50-F248C-D01-01 Page 46
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
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
Design Basis Report for BTG Electrical System
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DOCUMENT NO.: 50-F248C-D01-01 Page 47
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
Design Basis Report for BTG Electrical System
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DOCUMENT NO.: 50-F248C-D01-01 Page 48
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
detailed engineering
≤46
1
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
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DOCUMENT NO.: 50-F248C-D01-01 Page 49
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
Design Basis Report for BTG Electrical System
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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
Shall be provided during
detailed engineering
Yes
Brushless excitor
Yes
Shall be provided during
detailed engineering
1
1
1
Design Basis Report for BTG Electrical System
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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
Shall be provided during
detailed engineering
1.14
Shall be provided during
1
Design Basis Report for BTG Electrical System
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DOCUMENT NO.: 50-F248C-D01-01 Page 52
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)
detailed engineering
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
Design Basis Report for BTG Electrical System
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DOCUMENT NO.: 50-F248C-D01-01 Page 53
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
Shall be provided during
detailed engineering
Shall be provided during
detailed engineering
1
1
1
1
1
1
1
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
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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
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DOCUMENT NO.: 50-F248C-D01-01 Page 55
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%
Design Basis Report for BTG Electrical System
HPGC : 2 x 300 MW Deenbandhu Chhotu Ram
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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
Design Basis Report for BTG Electrical System
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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
Design Basis Report for BTG Electrical System
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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
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ANNEXURE III Generator capability curve
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ANNEXURE IV Generator overfluxing capability curve
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ANNEXURE V Generator saturation curve
Line V
oltage (kV)
Line C
urrent (A)
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ANNEXURE VI Generator vee curve
Leading
Lagging
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ANNEXURE VII Exciter characteristic curve