Generator Relay Settings

TITLE : RELAY SETTING CALCULATIONS

FOR GENERATOR RELAY PANELS

JPL, OP JINDAL SUPER TPP (4 X 250 MW)

DOCUMENT NO. PE-DG-233-510-E017 REV NO. : 0 DATE : 14/05/2007 SHEET : 1 OF 21

GENERATOR PARAMETERS RATED OUTPUT : 294.12MVA : 250 MW RATED VOLTAGE : 16.5 kV RATED CURRENT : 10291 A RATED FREQUENCY : 50 Hz RATED POWER FACTOR : 0.85 LAG DIRECT AXIS SUB-TRANSIENT REACTANCE (SATURATED) Xd”

: 15.5%

DIRECT AXIS TRANSIENT REACTANCE (SATURATED) Xd’

: 22.8%

DIRECT AXIS SYNCHRONOUS REACTANCE (SATURATED) Xd

165%

TOLERANCE ON REACTANCE : + 15% MAXIMUM CONTINUOUS NEGATIVE PHASE SEQUENCE CURRENT (I2)

: 8%

MAXIMUM VALUE OF I22t : 10 GENERATOR TRANSFORMER PARAMETERS (CUSTOMER SCOPE) RATING : 315MVA IMPEDANCE : 14% + 10% TOL. AT PRINCIPAL TAP VOLTAGE RATIO : 420/ 16.5 kV TAP CHANGER RANGE : + 5% TO –5% UNIT AUXILIARY TRANSFORMER PARAMETERS (CUSTOMER SCOPE) RATING : 20 MVA IMPEDANCE : 10% + 10% TOL. AT PRINCIPAL TAP VOLTAGE RATIO : 16.5/6.9 kV TAP CHANGER RANGE : + 10% TO –10% RATED HV SIDE CURRENT : 699.839 A





GENERATOR PROTECTION RELAY (GR1 & GR2) DEVICE NO. : GR1 & GR2 TYPE OF RELAY : 7UM62 A. GENERATOR BACK UP IMPEDANCE PROTECTION (21G1[GR1], 21G2[GR2]) IMPEDANCE OF GT (ZT) = 14.0% = 0.14 P.U.

= 3155.165.1614.0 x

× OHM

= 0.121 OHM CT RATIO = 12500 / 5 A VT RATIO =

3/1103/16500

V

IMPEDANCE ZONE Z1 = 70% OF ZT

= RATIOVT

RATIOCTT

Zx

7.0 ×

=

3/165003/110

512500x121.0x0.7 ×

= 1.4114 OHM

SELECTED Z1 = 1.5 OHM TIME DELAY OF ZONE Z1 = 1.00 SECOND (*) IMPEDANCE ZONE Z2 = 100% OF ZT

=

RATIOVT

RATIOCTT

Z

×

=

3/165003/110

512500x121.0 ×

= 2.008 OHM

SELECTED Z2 = 2.10 OHM TIME DELAY OF ZONE Z2 = 2.00 SECOND (*)

*: TIME DELAY TO BE COORDINATED AT SITE WITH DISTANCE PROTECTION





B. UNDER VOLTAGE RELAY FOR 40G1 & 40G2 (27G1[GR1] & 27G2[GR2]) VOLTAGE SETTING RANGE : 10.0 – 125.0V TIME SETTING RANGE : 0 – 60 SECOND VOLTAGE SETTING : 77V TIME SETTING : 10 SECOND C. GENERATOR REVERSE POWER PROTECTION (32G [GR1] In case of a reverse power, the turbine set must be disconnected from the system as the turbine operation is not permissible without a certain minimum steam throughput (cooling effect) or, in case of a gas turbine set, the motor load would be too heavy for the network. For the primary test, the reverse power should be measured with the actual protection. The user should select a setting of 0.5 times the value of the measured motoring energy. This value can be found under the percentage operational measured values. The feature to correct angle faults of the current and voltage transformers should be used especially for very large machines with a particularly low motoring energy. The pickup value is set in percent of the secondary apparent power rating SNsec = √3 · UNsec · INsec If the primary motoring energy is known, it must be converted to secondary quantities using the following formula:

with Psec = Secondary power corresponding to setting value SNsec = secondary nominal power = √3 · UNsec · INsec PMach = Machine power corresponding to setting value

= -0.5% of 250 MW = -1.25 MW SN, Mach = Nominal apparent power of the machine = 294 MVA UN Mach = Nominal voltage of the machine = 165000 V IN Mach = Nominal current of the machine = 10291 A UN prim = Primary Nominal Voltage of the voltage transformers = 165000 V IN prim = Primary nominal current of the current transformer = 125000 A

sec

sec

NSP

= 1250016500294102911650025.1

××××−

= -0.350%

SETTINGS SELECTED : RECOMMENDED POWER SETTING : -0.5% TIME SETTING (CLASS B) : 2 SECONDS TIME SETTING (CLASS A) : 10 SECONDS





D. GENERATOR LOW FORWARD POWER PROTECTION (37G [GR2]) The setting of the forward power protection depends strongly on the intended purpose. General setting guidelines are not possible. The pickup values are set in percent of the secondary apparent power rating SNsec = √3 · UNsec · INsec. Consequently, the machine power must be converted to secondary quantities:

with Psec = Secondary power corresponding to setting value SNsec = secondary nominal power = √3 · UNsec · INsec PMach = Machine power corresponding to setting value

= 0.5% of 250 MW = 1.25 MW SN, Mach = Nominal apparent power of the machine = 294 MVA UN Mach = Nominal voltage of the machine = 165000 V IN Mach = Nominal current of the machine = 10291 A UN prim = Primary Nominal Voltage of the voltage transformers = 165000 V IN prim = Primary nominal current of the current transformer = 125000 A

sec

sec

NSP

= 1250016500294102911650025.1

××××

= 0.350%

SETTINGS SELECTED : RECOMMENDED POWER SETTING : 0.5% TIME SETTING : 0 SECOND

TIME DELAY RELAY FOR 37G1 (SOFT TIMER-1 IN & GR2) TIME SETTING RANGE : 0 – 5.0 SEC. TIME SETTING : 2.0 SECOND TIME DELAY RELAY FOR 37G1 & 37G2 (SOFT TIMER-2 IN GR2) TIME SETTING RANGE : 0 - 50.0 SEC. TIME SETTING : 10.0 SECOND E. GENERATOR FIELD FAILURE PROTECTION (40G1[GR1], 40G2[GR2]) CONDUCTANCE INTERSECT CHAR. 1 : 0.25 – 3.00 INCLINATION ANGLE OF CHAR. 1 : 50o – 120o CHAR. 1 TIME SETTING RANGE : 0 – 60 SECOND CONDUCTANCE INTERSECT CHAR. 2 : 0.25 – 3.00 INCLINATION ANGLE OF CHAR. 2 : 50o – 120o CHAR. 2 TIME SETTING RANGE : 0 – 60 SECOND CONDUCTANCE INTERSECT CHAR. 3 : 0.25 – 3.00 INCLINATION ANGLE OF CHAR. 3 : 50o – 120o CHAR. 3 TIME SETTING RANGE : 0 – 60 SECOND





Characteristic Curves The following figure shows the loading diagram of the synchronous machine in the admittance plane (P/U2; –Q/U2) with the statistic stability limit which crosses the reactive axis near 1/Xd (reciprocal value of the synchronous direct reactance).

Figure E-1 Admittance Diagram of Turbo Generators

The underexcitation protection in the 7UM62 makes available three independent, freely combinable characteristics. As illustrated in the following figure, it is possible for example to model static machine stability by means of two partial characteristics with the same time delays (T CHAR. 1 = T CHAR 2). The partial characteristics are distinguished by the corresponding distance from the zero point (1/xd CHAR. 1) and (1/xd CHAR. 2) as well as the corresponding inclination angle α1 and α2 If the resulting characteristic (1/xd CHAR.1)/α1; (1/xd CHAR.2)/α2 is exceeded (in the following figure on the left), a delayed warning (e.g. by 10 s) or a trip signal is transmitted. The delay is necessary to ensure that the voltage regulator is given enough time to increase the excitation voltage.





Figure E-2 Stator circuit criterion: Pick–Up Characteristic in Admittance Diagram A further characteristic (1/xd CHAR.3 /α1 can be matched to the dynamic stability characteristic of the synchronous machine. Since stable operation is impossible if this characteristic is exceeded, immediate tripping is then required (time stage T CHAR 3). The primary setting values can be read out directly from the diagram. The related values must be converted for the protection setting. The same conversion formula can be used if the protection setting is performed with the predefined synchronous direct reactance.

with xdsec related synchronous direct reactance, secondary, xd mach related synchronous direct reactance of the machine = 1.65 INMach Nominal current of the machine = 10291 A UNMach Nominal Voltage of the Machine = 16500 V UN, CTprim Primary Nominal Voltage of the voltage transformers = 16500 V IN, CT prim Nominal primary CT current = 12500 A

1250016500

1650010291

65.111

sec

••=dx

= 0.498





multiplied by a safety factor of 1.05, the setting value of CHAR. 1 = 1.05 x 0.498 = 0.5229 with an angle of 80o. Time delay setting 2.0 Second. CHAR. 2 is set to 0.9 times CHAR. 1 = 0.9 x 0.5229 = 0.4706 with an angle of 90o. Time delay setting 2.0 Second. CHAR. 3 is set to 2 times CHAR. 2 = 2 x 0.4706 = 0.9412 with an angle of 100o. Time delay setting 0.3 Second. F. GENERATOR NEGATIVE SEQUENCE PROTECTION (46G1[GR1], 46G2[GR2]) SETTING RANGE NEGATIVE PHASE SEQ. CURRENT TRIP : 10 - 100% NEGATIVE PHASE SEQ. CURRENT ALARM : 3.0 – 30% TRIP DELAY : 0 – 60 SECOND ALARM DELAY : 0 – 60 SECOND NEGATIVE SEQUENCE FACTOR, Ksec : 2.0 – 100.0 SECOND TIME FOR COOL DOWN, tcooldown : 0 – 50000 SECOND

with I2 max prim Permissible thermal inverse current of the motor IN Machine Nominal current of the machine = 10291 A IN CT prim Primary nominal current of the current transformer = 12500 A

Generator continuous negative phase sequence current capability = MachineN

prim

II max2

= 8%

I2> (ALARM) = 8 1250010291⋅ % = 6.59% with time delay 20 second.

I2>> (TRIP) = 65% primCTN

MachineN

II⋅

= 65% 1250010291

= 53.51% with time delay of 1.5 second

Negative sequence factor, Kprimary = ( ) tII

MachineN

prim ⋅2max2

= 10 second

Ksec = Kprimary ( )2

primCTN

MachineN

II

⋅

= 10 2

1250010291

⎟⎠⎞

⎜⎝⎛

second

= 6.77 SECOND





tcooldown = ( )2max2 MachineNprim

primary

II

K

= ( )208.0

10 second

= 1563 SECOND

G. GENERATOR DEAD MACHINE PROTECTION (50GDM1[GR1], 50GDM2[GR2]) CURRENT SETTING RANGE : 0.1 – 20.0 A BASE MVA = 294 MVA GENERATOR TRANSIENT REACTANCE (SATURATED) (Xd’)

= 22.8%

MAXIMUM VALUE OF Xd’ CONSIDERING TOL. = 1.15×22.8 = 26.22% GENERATOR TRANSFORMER IMPEDANCE = 14.0% MAXIMUM VALUE OF GT IMPEDANCE CONSIDERING TOLERANCE

= 1.1×14.0%

= 15.4% 400kV SYSTEM FAULT LEVEL = 40kA = √3x40x400 MVA = 27712 MVA 400kV SYSTEM IMPEDANCE AT 294MVA BASE

= 27712294

= 0.0106 P.U. SHORT CIRCUIT CURRENT (P.U.)ISC = 1/(0.154 + 0.0106 + 0.2622) = 1/0.4268 = 2.343 P.U. GENERATOR CURRENT = 10291 A CT SECONDARY CURRENT CORRESPONDING TO 10291 A

=

12500

502911 ×

= 4.12 A SHORT CIRCUIT CURRENT (IN AMP) = 4.12 x 2.343 = 9.653 A (i.e. 234% of FLC of generator) HOWEVER, RELAY IS SET AT RATED FULL LOAD CURRENT OF GENERATOR

= 4.12 A

RECOMMENDED CURRENT SETTING = 4.2 A TIME DELAY RELAY FOR FOR 50GDM1 & 50GDM2 (SOFT TIMER-TDPU IN GR1 & GR2) TIME SETTING RANGE : 0.1 – 1.0 SEC. TIME SETTING : 1.0 SECOND TIME DELAY RELAY FOR FOR 50GDM1 & 50GDM2 (SOFT TIMER-TDDO IN GR1 & GR2) TIME SETTING RANGE : 0.1 – 1.0 SEC. TIME SETTING : 1.0 SECOND





H. GENERATOR DEFINITE TIME OVERLOAD PROTECTION (51G1[GR1] & 51G2[GR2]) [USING CFC]

CURRENT SETTING RANGE : 0.10 – 20.0 A TIME SETTING RANGE : 0 – 60 SECOND CT RATIO : 12500/5 A GENERATOR OUTPUT : 250 MW GENERATOR FULL LOAD CURRENT AT 95% OF RATED VOLTAGE

=

0.85x 95.05.163

1000250

××

× A

= 10833.42 A CT SECONDARY CURRENT CORRESPONDING TO 10833.42 A

=

12500542.10833 x

A

= 4.33 A GENERATOR OVERLOAD CAPABILITY : 10% FOR 3 MINUTES CURRENT SETTING : 4.77 A TIME SETTING : 25 SECOND CFC DIAGRAM IS SHOWN BELOW





I. GENERATOR OVERVOLTAGE PROTECTION (59G1[GR1]) & 59G2[GR2]) The setting of limit values and time delays of the overvoltage protection depends on the speed with which the voltage regulator can regulate voltage variations. The protection must not intervene in the regulation process of the faultlessly functioning voltage regulator. For this reason, the two-stage characteristic must always be above the voltage time characteristic of the regulation procedure. VOLTAGE SETTING (DEF TIME TRIP) : 132 V TIME SETTING (DEF TIMETRIP) : 1SEC VOLTAGE SETTING (INSTANTANEOUS) : 149 V TIME SETTING (INSTANTANEOUS) : 0.05 SEC J. VOID K. GENERATOR VT VOLTAGE SUPPLY SUPERVISION RELAY [60FL(VT1)[GR1] &

60FL(VT2)[GR2]] RATED VOLTAGE : 110V NO SETTING IS REQUIRED ON THE RELAY L. 100% GENERATOR STATOR EARTH FAULT PROTECTION (64G[GR1]) SETTING RANGES/STEPS WARNING STAGE R< : 20 – 700 OHM TRIPPING STAGE R<< : 20 – 700 OHM CURRENT STAGE I>> : 0.02 – 1.50 A 20 Hz VOLTAGE FAILURE SUPERVISION BLOCK U20< : 0.3 – 15.0 V BLOCK I20< : 5 – 40 mA TRANSFORMER ANGLE ERROR CORRECTION CT ANGLE W1

: -60 TO +60

TRIP DELAY : 0 – 60 SECOND ALARM DELAY : 0 – 60 SECOND SETTINGS TRANSFORMATION FACTOR, S/E/F -FACTOR = TRETr

2 x (TRVD / TRICT) TRETr TRANSFORMATION RATIO OF

THE NGT = 16500/240 V TRVD TRANSFORMATION RATIO OF

THE VOLTAGE DIVIDER = 500/200 V TRICT TRANSFORMATION RATIO OF

THE INTERMEDIATE CURRENT TRANSFORMER = 600/5 A

= (16500/240)2 x [(500/200)/(600/5)] : 98.458 PICK UP VALUE OF THE WARNING STAGE OF STATOR EARTH FAULT PROTECTION

: 10000/98.458 OHM

: 102 OHM (*) TIME DELAY OF THE WARNING STAGE : 10 SECOND PICK UP VALUE OF THE TRIPPING STAGE OF STATOR EARTH FAULT PROTECTION

: 3000/98.458 OHM

: 30.46 OHM TIME DELAY OF THE TRIPPING STAGE : 1 SECOND





NGT PERCENT IMPEDANCE = 5.0 P.U. NGT PRIMARY IMPEDANCE, R =

05.0075.05.16 2

×

= 182 OHM PICK VALUE OF THE CURRENT TRIPPING STAGE S/E/F I>>

=

TRICTx

R

VOLTAGEPRIMARYNGT 10.2 ×

=

6005

182

165000.2x

×

= 0.15 A PICK-UP THRESHOLD OF 20 Hz UNDER VOLTAGE BLOCKING

: 1 V

PICK-UP THRESHOLD OF 20 Hz UNDER CURRENT BLOCKING

: 10 mA (*)

ANGLE ERROR COMPENSATION OF EARTHING CT AND INERMEDIATE CT

: 0 DEG (*)

* : FINAL SETTINGS SHALL BE DONE DURING COMMISSIONING BASED ON PRIMARY TESTS TO BE CARRIED OUT AT SITE AS PER OPERATING INSTRUCTION OF THE RELAY. M. GENERATOR STATOR EARTH FAULT PROTECTION (64G1[GR1]) The criterion for the occurrence of an earth fault in the stator circuit is the emergence of a neutral displacement voltage. Exceeding the set value U0> therefore causes pickup for stator earth protection.

Pickup value of earth fault detection = %100

%)95%100( VOLTAGESECONDARYVT×− V

= %100

110%)95%100( ×− V

= 5.5 V VOLTAGE SETTING : 5.5 V TIME SETTING : 0.2 SECOND





N. GENERATOR STATOR EARTH FAULT PROTECTION (64G2[GR2]) The criterion for the occurrence of an earth fault in the stator circuit is the emergence of a neutral displacement voltage. Exceeding the set value U0> therefore causes pickup for stator earth protection. TRVD TRANSFORMATION RATIO OF THE VOLTAGE DIVIDER = 500/200 V

Pickup value of earth fault detection = %100

TR/%)95%100( VDVOLTAGESECNGT×− V

= %100

500200240%)95%100( ××−

V

= 4.8 V VOLTAGE SETTING : 4.8 V TIME SETTING : 0.2 SECOND O. GENERATOR ROTOR EARTH FAULT PROTECTION (64R[GR1]) SETTING RANGES/STEPS WARNING STAGE RE< WARN AND RE<TEST : 5 – 80 KOHM TRIPPING STAGE RE<< TRIP AND RE<< TEST : 1 – 10 KOHM PICK-UP VALUE OF MEAS. CIRCUIT SUPERVISION Qc<

: 0.00 – 1.00mA

TRIP DELAY : 0 – 60 SECOND ALARM DELAY : 0 – 60 SECOND ALARM SETTING : 40 KOHM TRIP SETTING : 5 KOHM TIME DELAY SETTING FOR WARNING STAGE : 10 SECOND TIME DELAY SETTING FOR TRIPPING STAGE : 1 SECOND

CHARGE Qc DURING POLARITY REVERSAL BELOW WHICH THE MEASURING CIRCUIT IS ASSUMED TO BE OPEN

: 0.02 mA (*)

*: THE FINAL SETTING OF CHARGE Qc HAS TO BE DETERMINED DURING COMMISSIONING. P. UNDER FREQUENCY PROTECTION (81G1[GR1], 81G2[GR2]) By configuring the rated frequency of the power system and the frequency threshold for each of the stages f1 PICKUP to f4 PICKUP in each case the function is established as either overfrequency or underfrequency protection. Set the pickup threshold lower than nominal frequency if the element is to be used for underfrequency protection. FIRST STAGE – ALARM FREQUENCY SETTING RANGE(f1) : 40 - 66 Hz TIME SETTING RANGE (t1) : 0 - 600 SEC. FREQUENCY SETTING (f1) : 48.5 Hz TIME SETTING (t1) : 2.5 SECOND SECOND STAGE – CLASS C TRIPPING FREQUENCY SETTING RANGE(f2) : 40 - 66 Hz TIME SETTING RANGE (t2) : 0 - 100 SEC. FREQUENCY SETTING (f2) : 47.4 Hz





TIME SETTING (t2) : 2.0 SECOND Q. GENERATOR DIFFERENTIAL PROTECTION (87G[GR1]) Pick up value of differential current, IDIFF> : 0.1 I/IN Machine Time delay T IDIFF> : 0.00 SECOND Pick up value of high set trip, IDIFF>> :

'

1

dX (I/IN Machine)

:

228.01

(I/IN Machine)

: 4.385 (I/IN Machine) Time delay T IDIFF>> : 0.00 SECOND Slope 1 of tripping characteristic : 0.15 Base Point of Slope 1 : 0.00 (I/IN Machine) Slope 2 of tripping characteristic : 0.5 Base Point of Slope : 0.00 (I/IN Machine) Pick up for Add-on stabilization : 4.00 (I/IN Machine)

Duration of Add-on stabilization : 15 CYCLES R. GENERATOR OUT OF STEP (POLE SLIPPING) RELAY (98G1[GR1], 98G2[GR2]) CT RATIO, TRCT : 12500/5 A VT RATIO, TRVT :

3110/

316500

V

SOURCE IMPEDANCE (Zs) : kV2/FAULT MVA : 16.52/27712 = 0.00982OHM Zd-Zc =

VT

CTS TR

TRZ ×

=

3165003110

5125000.00982 ××

= 0.1632 OHM GENERATOR POLE SLIPPING IMPEDANCE (ZG) = 0.85 X 0.155 X 16.52/294 = 0.1220 OHM Zb =

VT

CTG TR

TRZ ×

=

3165003110

5125001220.0 ××

= 2.03293 OHM GENERATOR TRANSFORMER IMPEDANCE (ZT) = 0.14 X 16.52/315 = 0.121 OHM Zc =

VT

CTT TR

TRZ ×

=

3650013110

512500121.0 ××

= 2.01634 OHM





Figure Q1 : Polygonal Out-of-Step Characteristic with Typical Power Swings





Figure Q2 : Power swing polygon and impedance vectors with angle δ Ztot = cb ZZ + = 2.03293 + 2.01634 = 4.0492 OHM Za = 0.289 x 4.0492 = 1.17 OHM Measurement is enabled only if the positive sequence component of the currents has exceeded a minimum threshold 3502 I1> RELEASE (overcurrent pickup). Also because of the symmetry condition, a maximum value of negative sequence current 3503 I2< RELEASE must not be exceeded. I1> RELEASE = 120% IN GENERATOR I2< RELEASE = 20% IN GENERATOR S. GENERATOR TRANSFORMER OVER FLUXING PROTECTION (99GT1[GR1],

99GT2[GR2]) GENERATOR TRANSFORMER OVERFLUXING WITHSTAND CAPABILITY AND OPERATING TIME OF THE RELAY (INVERSE UNIT) ARE TABULATED BELOW:

GENERATOR TRANSFORMER OVERFLUXING WITHSTAND CAPABILITY

RELAY OPERATING TIME (INVERSE UNIT)

VALUE TIME 1.10 2400 SECOND 36 SECOND 1.15 660 SECOND 16 SECOND 1.20 230 SECOND 9 SECOND 1.25 90 SECOND 5.76 SECOND 1.30 40 SECOND 4 SECOND 1.35 14 SECOND 2.94 SECOND 1.40 6 SECOND 2.25 SECOND

U/f > PICKUP : 1.10 U/f > TIME DELAY : 10 SECOND U/f >> PICKUP : 1.40 U/f >> TIME DELAY : 1 SECOND





GENERATOR INTERTURN FAULT PROTECTION (64GIT) DEVICE NO. : 64GIT TYPE OF RELAY : 7SJ62 In case of single turn inter turn fault, unbalance produced in faulty phase leads to a voltage 0.939 p.u. in the faulty phase, with other two phase voltages being normal. Voltage across open delta secondary

VOD = ( VR VY VB+ +→ → →

) N, where, N is inverse of the transformation ratio of IVT1 VOD = N [V(0.883) + VCos 120° + jVSin 120° + VCos 240° + jVSin240°] As VR = 0.939 V VY = VB = V VOD = NV (0.939 - 0.5 + j 0.866 - 0.5 - j 0.866) = NV (0.939 - 1) = NV (- 0.061) ⎜VOD ⎜ = 0.061 V. N

IVT1 ratio = 110 80 = N1

√3 √3 V = 110/√3 V ⎜VOD⎜ = 0.061 x [110/√3] x [(80/√3)/(110/√3)] = 2.72 V IVT2 ratio is such so that relay at minimum setting is able to pick up on single turn fault and at the same time does not experience more than 200V IVT2 secondary is therefore chosen such that it does not reflect more than 200V for complete one phase of generator winding short circuited (there being no voltage from NGT secondary for inter turn faults). Under this condition, ⎜ VOD ⎜ = 1 x [110/√3] x [(80/√3)/(110/√3)] = 46.188 V Limiting values of open delta voltage are therefore 2.72 V and 46.188 V. IVT2 should step up open delta secondary voltage to more than relay pick-up value of 5.4 V but less than 200 V for a primary voltage of 46.188 V Choosing IVT2 secondary of 110V, the primary rating is = 110 x 46.188 200 = 25.4 V IVT2 ratio is 25.4/110 V.





This gives a voltage of [(110 x 2.72)/ 25.4] = 11.7V on a single turn fault which is sufficient to ensure positive operation of relay for a setting of 10V.

VOLTAGE SETTING : 10V TIME MULTIPLIER SETTING : 0.1 GENERATOR VT VOLTAGE SUPPLY SUPERVISION RELAY (60VT1, 60VT2, 60VT3 DEVICE NO. : 60VT1, 60VT2 & 60VT3 TYPE OF RELAY : MVAPM32 RATED VOLTAGE : 110V NO SETTING IS REQUIRED ON THE RELAY GENERATOR ON RELAY (97G) DEVICE NO. : 97G TYPE OF RELAY : VAA11 RATED VOLTAGE : 110V NO SETTING IS REQUIRED ON THE RELAY GRP GROUP 1 DC SUPPLY SUPERVISION RELAY (80G1) DEVICE NO. : 80G1 TYPE OF RELAY : VAG11 NO SETTING IS REQUIRED ON THE RELAY

GRP GROUP 2 DC SUPPLY SUPERVISION RELAY (80G2) DEVICE NO. : 80G2 TYPE OF RELAY : VAG11 NO SETTING IS REQUIRED ON THE RELAY





GENERATOR TRANSFORMER PROTECTION RTELAY – GTR2 (51NGT/ 87GT) DEVICE NO. : GTR1 TYPE OF RELAY : 7UT613 A. GENERATOR TRANSFORMER BACKUP EARTH FAULT PROTECTION (51NGT) CURRENT SETTING RANGE, IE > : 0.25 – 175.00 A TIME SETTING RANGE : 0.0 – 60.0 SECOND CT RATIO : 500/1 A CURRENT SETTING, IE > : 0.1 A TIME SETTING : 2.0 SECOND

[TO BE GRADED WITH 400KV SYSTEM]

THE ABOVE TIME SETTING SHALL BE CO-ORDINATED WITH LINE PROTECTION. [CUSTOMER MAY PLEASE ADVISE 220kV SIDE DISTANCE PROTECTION TIME SETTING] B. GENERATOR TRANSFORMER DIFFERENTIAL PROTECTION (87GT) Pick up value of differential current, IDIFF> : 0.1 I/IN Machine Time delay T IDIFF> : 0.00 SECOND Pick up value of high set trip, IDIFF>> :

"

1

dX (I/IN GT)

:

)9.0(14.01

(I/IN GT)

: 7.9365 (I/IN GT) Selected Pick up value of high set trip, IDIFF>> : 10 (I/IN GT) Time delay T IDIFF>> : 0.00 SECOND Slope 1 of tripping characteristic : 0.20 Base Point of Slope 1 : 0.20 (I/IN GT) Slope 2 of tripping characteristic : 0.80 Base Point of Slope 2 : 2.00 (I/IN GT) Pick up for Add-on stabilization : 4.00 (I/IN GT) Duration of Add-on stabilization : 15 CYCLES GENERATOR TRANSFORMER RESTRICTED EARTH FAULT PROTECTION (64RGT [GTR1] A. GENERATOR TRANSFORMER RESTRICTED EARTH FAULT PROTECTION (64RGT) DEVICE NO. : 64RGT TYPE OF RELAY : 7SJ61 CT RATIO : 500/1A RCT : 5.0 OHM

MAXIMUM FAULT CURRENT (HV SIDE) :

Z(min.)3

1000MVA

××

×

HVVOLTAGE A





=

0.14x0.94203

1000315

××

× A

= 3436.7095 A FAULT CURRENT ON CT SECONDARY =

5001 3436.7095 × A

= 6.87 A

VOLTAGE ACROSS THE RELAY UNDER THROUGH FAULT CONDITION

: If (RCT + 2RL)

NEGLECTING LEAD RESISTANCE = 6.87 X5.0 = 34.35 V SET THE RELAY AT 5% 0F 1A SETTING CURRENT : 0.05 A CURRENT REQUIRED FOR RELAY OPERATION = 0.05 A VALUE OF STABILISING RESISTOR =

05.035.34

= 687 OHM VALUE OF STABILISING RESISTOR : 700 OHM OVERALL DIFFERENTIAL PROTECTION RELAY – GTR3 ( 87OA) DEVICE NO. : 87GT TYPE OF RELAY : 7UT635 Pick up value of differential current, IDIFF> : 0.1 I/IN Machine Time delay T IDIFF> : 0.00 SECOND Pick up value of high set trip, IDIFF>> :

"

1

dX (I/IN OA)

:

9.014.01x

(I/IN OA)

: 7.9365 (I/IN OA) SELECTED IDIFF>> : 10.0 (I/IN OA) Time delay T IDIFF>> : 0.00 SECOND Slope 1 of tripping characteristic : 0.20 Base Point of Slope 1 : 0.20 (I/IN OA) Slope 2 of tripping characteristic : 0.80 Base Point of Slope 2 : 2.0(I/IN OA) Pick up for Add-on stabilization : 4.00 (I/IN OA) Duration of Add-on stabilization : 15 CYCLES





UNIT AUXILIARY TRANSFORMER PROTECTION RELAY UATAR1/ UATBR1 (50/51UAT, 64UAT) DEVICE NO. : UATAR1, UATBR1 TYPE OF RELAY : 7SJ61 A. UAT HV OVER CURRENT PROTECTION (50/51UAT)

CT RATIO : 800/1A LOAD ON 6.6kV UNIT BUS PRIOR TO STARTING OF BFP MOTOR

: 12.52 MVA*

STARTING CURRENT OF BFP MOTOR = 2.8404 kA STARTING MVA OF BFP MOTOR = sqrt(3) x 2.8404 x 6.6 = 32.47 MVA LOAD DETAILS ON 6.6kV UNIT BUS DURING STARTING OF BFP MOTOR ARE TABULATED BELOW (*):

LOAD DESCRIPTION MVA COS φ SIN φ MW MVAR BASE LOAD PRIOR TO STARTING OF BFP MOTOR

12.52 0.85 0.526 10.64 6.58

STARTING MVA FOR BFP MOTOR 32.47 0.2 0.979 6.49 31.79 TOTAL 17.13 38.37 TOTAL MVA LOAD ON UAT DURING STARTING OF BFP MOTOR

= 22 )37.38()13.17( + = 42.02 MVA UT HV SIDE CURRENT =

5.163

42.02

× kA

= 1.4704 KA CT SECONDARY CURRENT CORRESPONDING TO 1470 A

= (1470x1)/800 A

= 1.8375 A CURRENT SETTING : 1.9 A TIME SETTING : 0.9 SECOND * : M/s JPL to check and confirm at their end, as Electrical System

Design (JPL scope) has not been done by BHEL. Data indicated is from a similar 250MW project. However, exact loads on unit bus may vary based on rating of the drives & down stream LT loads.

B. UNIT AUXILIARY TRANSFORMER RESTRICTED EARTH FAULT PROTN (64RUAT) CT RATIO : 2000/1A RCT : 2.0 OHM

MAXIMUM FAULT CURRENT (HV SIDE) :

Z(min.)3

1000MVA

××

×

LVVOLTAGE A

=

0.9 x 0.1 9.63

100020

××

× A

= 27892.13 A FAULT CURRENT ON CT SECONDARY =

20001 18596 ×

= 9.298 A





VOLTAGE ACROSS THE RELAY UNDER THROUGH FAULT CONDITION

: If (RCT + 2RL)

NEGLECTING LEAD RESISTANCE = 9.298 X2.0 = 18.59 V SET THE RELAY AT 10% 0F 1A SETTING CURRENT : 0.1 A CURRENT REQUIRED FOR RELAY OPERATION = 0.1 A VALUE OF STABILISING RESISTOR =

1.059.18

= 185.9 OHM VALUE OF STABILISING RESISTOR : 250 OHM UNIT AUXILIARY TRANSFORMER PROTECTION RELAY UATAR2/ UATBR2 (87UAT, 51NUAT) A. UNIT AUXILIAR TRANSFORMER DIFFERENTIAL PROTECTION (87UAT) Pick up value of differential current, IDIFF> : 0.2 I/IN Machine Time delay T IDIFF> : 0.00 SECOND Pick up value of high set trip, IDIFF>> :

"

1

dX (I/IN UAT)

:

09.01

(I/IN UAT)

: 11.11 (I/IN UAT) Time delay T IDIFF>> : 0.00 SECOND Slope 1 of tripping characteristic : 0.25 Base Point of Slope 1 : 0.00 (I/IN UAT) Slope 2 of tripping characteristic : 0.50 Base Point of Slope 2 : 2.5 (I/IN UAT) 2nd Harmonic content : 15% Cycle Time for Cross-blocking 2nd Harmonic : 3 CYCLE 5th Harmonic content : 30% Cycle Time for Cross-blocking 5th Harmonic : 0 CYCLE Limit IDIFFmax of 5th Harm.Restraint : 1.5 (I/IN UAT) Pick up for Add-on stabilization : 4.00 (I/IN UAT) Duration of Add-on stabilization : 15 CYCLES Increase of Trip Char. During Start : OFF B. UNIT AUXILIARY TRANSFORMER LV BACKUP EARTH FAULT PROTECTION

(51NUAT) CURRENT SETTING RANGE, IE > : 0.05 – 35.00 A TIME SETTING RANGE : 0.0 – 60.0 SECOND CT RATIO : 200/1 A CURRENT SETTING, IE > : 0.05 A TIME SETTING : 2.0 SECOND THE ABOVE TIME SETTING SHALL BE CO-ORDINATED WITH LINE PROTECTION. [CUSTOMER MAY PLEASE ADVISE 220kV SIDE DISTANCE PROTECTION TIME SETTING]

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Generator Relay Settings