Generator Protn

7/28/2019 Generator Protn

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GRID

Technical Institute

This document is the exclusive property of Alstom Grid and shall not be

transmitted by any means, copied, reproduced or modified without the priorwritten consent of Alstom Grid Technical Institute. All rights reserved.

Generator Protection


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Generator Protection - P 2


The extent and types of protection specified will depend on the following factors :-

Type of prime mover and generator construction

MW and voltage ratings

Mode of operation

Method of connection to the power system

Method of earthing


3/111



Types of Prime Mover

Steam Turbines

Gas Turbines

Hydro

Diesel

Construction Cylindrial Rotor

Salient Pole (Hydro and small generators)

Mode of operation

Base load

Peak lopping

Standby

Ratings

Power from 200kVA to 1000MVA

Voltage from 440V to 24kV


4/111


Connection to the Power System

1. Direct :

2. Via Transformer :


5/111


Generator Protection Requirements

To detect faults on the generator

To protection generator from the effects of abnormal power system operatingconditions

To isolate generator from system faults not cleared remotely

Action required depends upon the nature of the fault.

Usual to segregate protection functions into :

Urgent

Non-urgent

Alarm


6/111


Generator Faults

Mixture of mechanical and electrical problems.

Faults include :-

Insulation Failure Stator

Rotor

Excitation system failure Prime mover / governor failure

Bearing Failure Excessive vibration Low steam pressure etc.


7/111


System Conditions

Short circuits

Overloads

Loss of load

Unbalanced load Loss of synchronism


8/111


Generator Failure


9/111


Generator Failure


10/111


Generator Failure


11/111


Generator Failure


12/111


Stator Earth Fault Protection

Fault caused by failure of stator winding insulation

Leads to burning of machine core

welding of laminations

Rebuilding of machine core can be a very expensive process

Earth fault protection is therefore a principal feature of any generator protection package

TYPE OF METHOD METHOD

PROTECTION OF OFEARTHING CONNECTION


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Method of Earthing

Machine stator windings are surrounded by a mass of earthed metal

Most probable result of stator winding insulation failure is a phase-earth fault

Desirable to earth neutral point of generator to prevent dangerous transient

overvoltages during arcing earth faults Several methods of earthing are in use

Damage resulting from a stator earth fault will depend upon the earthing

arrangement


14/111


Method of Earthing

Solidly Earthed Machines :

Fault current is high

Rapid damage occurs burning of core iron

welding of laminations

Used on LV machines only


15/111


Generator - Transformer Units

IF ~ 200 300 A

IF ~ 10 15 A

Method of Earthing


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Method of Earthing

Desirable to limit earth fault current :

limits damage

reduces possibility of developing into phase - phase fault

Degree to which fault current is limited must take into account :

detection of earth faults as near as possible to the neutral point

ease of discrimination with system earth fault protection (directly connected

machines)


17/111


Method of Earthing : Limitation of Earth

Fault Current

Discrimination not required can limit current to very low value. Sometimes

down to 5A

F

Earth faults on the power system are not

seen by the generator earth fault

protection.


18/111


Method of Earthing : Limitation of Earth

Fault Current

Limit To Generator Full Load Current

Most popular.

Used for ease of fault detection and discrimination.

Residual connection of CTs can be used

Can result in serious core damage.


19/111



Directly Connected Generators :

Earthed Generator : Earth fault relay must be time delayed for

co-ordination with other earth fault protection on the power system.

Unearthed Generators : Other generators connected in parallel

will generally be unearthed.

Protection is restricted to faults on the generator, grading with power system earth fault protection is not

required. A high impedance instantaneous relay can be used (Balanced Earth Fault protection).

51N

51N50N


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Percentage Winding Protected

xV

250/1A IS

33R

11.5kV; 75,000KVA

R

xV

F

0.8x250

1xx.200

x.20033

x.6600

R

xV

operationFor

Y)S(SECONDAR

FS(PRIMARY)

For protection of 90% of winding; x = 1-0.9 = 0.1

Relay setting = 0.8 x 0.1 = 0.08A = 8% of 1A


21/111



Generators connected via step-up transformer (resistance earthed) :

Instantaneous protection (50N) :

System earth faults ARE not seen by generator earth fault protection instantaneous relay may be used.

Set to 10% of resistor rating (avoids operation due to transient surges passed through generator transformer

interwinding capacitance).

Advantage : Fast

51N 50N


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Time delayed protection (51N) :

Time delay prevents operation on transient surges.

A more sensitive current setting may be used.

Set to 5% of resistor rating.

Advantage : Sensitive

On large machines considered worthwhile to use both

instantaneous and time delayed.


23/111


Restricted Earth Fault Protection

64

RSTAB

Protects approx. 90 - 95% of generator winding.


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z

TerminalCT

Inputs

E/F CT

Input

P342/3 Relay

2000/1 ?

500/1 ?

Connections for Biased REF

Smaller rating machines may have only one (neutral) tail CT brought out forconnection


25/111


0 1 2 3 4

1

2

3

Restrain

Operate

Biased REF Protection Operating

Characteristic

K1

High sensitivity (5%)

Unit Protection

FASTEffective bias (x In) = Max. phase current + k . I

N2

Differential current (x In)

= I + I + I + k . IA B C N


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Neutral Displacement / ResidualOvervoltage - Earth Fault Protection

P340

Relay

3

12

(1) Derived measurement from 5-limb or 3 x 1 phase VT

(2) Directly measured from a broken delta VT input

(3) Directly measured across an earthing resistor


27/111



100% Stator Earth Fault Protection :

Standard relays only cover 95% of winding.

Probability of fault occurring in end 5% is low. On large machines 100% stator earth fault protection

may be required.

Two methods :

Low Frequency Injection Third Harmonic Voltage Measurement


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100% Stator Earth Fault Protection (27TN)

(1) Derived measurement from 5-limb or 3 x 1 phase VT

(2) 3rd harmonic overvoltage

(3) 3rd harmonic undervoltage

3rd harmonic undervoltage supervised by 3 phase

undervoltage and W/VA/Var at generator terminals

P340

Relay

3

12


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100% Stator Earth Fault Protection

Distribution of 3rd harmonic voltage along the stator winding

(a) normal operation

(b) stator earth fault at star point

(c) stator earth fault at the terminals

100% St t E th F lt


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100% Stator Earth Fault -Low Frequency Injection

For Large Machines Only

InjectionTransformer

51 AlternativeInjectionPoints

Injection Frequency 12.5 -20Hz

Provides protection during runup & Standstill

High cost due to injectionequipment.


31/111


Overcurrent Protection

For small generators this may be the only protectionapplied.

With solid earthing it will provide some protectionagainst earth faults.

For a single generator, CTs must be connected to

neutral end of stator winding.

51


32/111



For parallel generators, CTs can be located on lineside.

51


33/111


Differential Protection

Provides high speed protection for all fault types

May be : High impedance type: Biased (low impedance) type

CTs required in neutral end of winding

Relay


34/111


Differential Protection - Biased

OPERATE

BIASBIAS

Biased Differential Scheme


35/111


Differential Protection

Overall Differential Scheme

INTERPOSINGC.T.


36/111


Independent current settings per phase

Single stage definite time delay

IA2

IB2

IC2

Interturn Protection (50DT)

Neutral Displacement / Residual


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Neutral Displacement / ResidualOvervoltage - Interturn Protection (59N)

Gen

Relay

3

1

2

(1) Interturn, derived measurement from 5-limb or 3 x 1 phase VT

(2) Interturn, directly measured from a broken delta VT input

(3) 95% stator earth fault protection across an earthing resistor


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Prime Mover Failure

Isolated Generators :Machine slows down and stops. Other protection initiates shut down.

Parallel Sets :

System supplies power - generator operates as a motor.Seriousness depends on type of drive.

Steam Turbine Sets :

Steam acts as a coolant.Loss of steam causes overheating.

Turbulence in trapped steam causes distortion of turbine blades.Motoring power 0.5% to 6% rated.Condensing turbines, rate of heating slow. Loss of steam instantlyrecognised.


39/111


Prime Mover Failure

Diesel Driven Sets :Prime mover failure due to mechanical fault.Serious mechanical damage if allowed to persist.Motoring power from 35% rated for stiff machine, to 5% rated for run inmachine.

Gas Turbines :

Motoring power 100% rated for single shaft machine, 10% to 15%rated for double shaft.

Hydro Sets :

Mechanical precautions taken if water level drops.Low head types - erosion and cavitation of runner can occur.

Additional protection may be required.


40/111


Prime Mover Failure

Reverse Power Protection :

Reverse power measuring relays used where protection required.

Single phase relay is sufficient as prime mover failure results inbalanced conditions.

Sensitive settings required - metering class CTs required for

accuracy.


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Reverse Power

Blinders at 0.5 degrees reduces operation area forlow power settings where the power factor is low toimprove reliability of reverse power element

Operational limits

Trip area

Q

Unstable areaUnstable area

P

astable

naturala = 0.16

o

-P= P0= 0.5o


42/111


Low Forward Power

To reduce the risk of overspeed damage to steam turbine generators a

low forward power element is used for interlocking the generator CBand excitation for non urgent trips (eg thermal protection, stator earthfault for high impedance earthing).

Turbine steam valves are tripped immediatelay and when poweroutput has reduced the generator CB and excitation are tripped.

Operational limits

Trip area

Q

Unstable area

Extended Trip areaP

0

P=P0

Trip area

a stable= 0.5o


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Loss of Excitation

Effects

Single Generator :

Loses output volts and therefore load.

Parallel Generators : Operate as induction generator (> synch speed) Flux provided by reactive stator current drawn from system-leading pf Slip frequency current induced in rotor - abnormal

heating

Situation does not require immediate tripping,

however,

large machines have short thermal time constants - should be unloadedin a few seconds.


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Loss of Excitation

X

Load Impedance

RImpedanceLocus

Offset Preventsoperationon pole slips

Diameter

Typically :Offset 50-75%Xd

Diameter 50-100% XS Time Delayed

Relay Characteristic

Impedance seen by relay follows locus shown below :


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Pole Slipping

Sudden changes or shocks in an electrical power system

may lead to power system oscillations - regular variationsof I and V and angular system separation

In a recoverable situation these oscillations will die away -a power swing

In an unrecoverable situation the oscillations become so

severe that synchronisation between the generator and thepower system is lost - out of step/pole slipping

Causes

Transient system faults Failure of the generator governor

Failure of the generators excitation control Reconnection of an islanded system without

synchronisation Switching transients on a weak system


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Pole slipping

Power Swing

Recoverable

Unrecoverable

Loss of Synchronism

Out-of-Step

(Power System)

Pole-Slipping

(Generator)


47/111


Theory of pole slipping

Where:

EG represents the generator terminal voltage;

ZG represents the generator reactance;

ZT is the reactance of step-up transform;Zs represents the impedance of the power system connected to the generation unit

Es represents the system voltage.

Simplified Two Machine System:


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Loss of synchronisation Characteristics

EG/ES1EG/ES=1

R

X S

G

L


49/111


Conventional Pole Slipping Protection

Reactance Line

R

Lens

Blinder

ZA

ZB

X

q

ZC

Zone 1

Zone 2


50/111


Pole Slipping Protection - 78

Conventional lenticular (lens) characteristic

2 Zones defined by reactance line Zone 1 - pole slip in the generator Zone 2 - pole slip in the power system

Separate counters per zone (1-20)

Setting to detect pole slipping when :

Generating Motoring

Both (Pumped storage generator)


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Pole Slipping Protection - 78

Pole slip when generating

Impedance position on RHS of lens characteristic Impedance crosses lens on RHS Impedance spends >T1 (15ms) in RHS of lens

Impedance spends >T2 (15ms) in LHS of lens Impedance leaves lens on LHS Zone 1 and 2 counter is incremented if in Z1 Zone 2 counter is incremented if in Z2 Trip when zone counter value exceeded

Pole slipping when motoring is the opposite


52/111


State Transition Diagram

IDLE

DETECTED START

CONFIRM

Zm = R1 .

Reset Start_Signals;

Reset Flag_Zone1;

IF(Any Trip_Signal)

Reset Counters;

Reset Trip_Signals;

(Zm = R4) & Timer2 > T2)

If (C2==0) Start Reset_Timer;C2++;

Set Zone2_Start;

if(C2>=Count2) Set Zone2_Trip ;

If (Flag_Zone1)

C1++;

Set Zone1_Start;

if(C1>=Count1) Set Zone1_Trip;

Reset Timer2;

(Zm = R3) & Timer1 > T1)

Flag_Zone1=Zone1Pu();

Reset Timer1;

Start Timer2;

Zm = R2

Start Timer1

Zm = R1 or R2

Reset Flag_Zone1;

Reset Timer2;

Zm = R3 but Timer1


53/111


RTDS Pole Slip Simulation

Local Load

T/line 140 km 11 kV BUS132/13.5 kV

Yd1

Grid System Generator withAVR and Governor control

132 kV BUS

S % f


54/111


Pole Slipping - 80% Load, Local 3 ph fault

L f it ti t 100% hi l di


55/111


Loss of excitation at 100% machine loading

Rotor Thermal


56/111


Rotor ThermalProtection

Unbalanced loading leads to negative sequencecurrent

Double frequency slip

Rapid overheating of rotor

U b l d L di


57/111


Unbalanced Loading

Gives rise to negative phase sequence (NPS) currents -results in contra-rotating magnetic field

Stator flux cuts rotor at twice synchronous speed

Induces double frequency current in field system androtor body

Resulting eddy currents cause severe over heating

Use negative sequence overcurrent relay Relay should have inverse time characteristic to

match generator I22t withstand

U b l d L di


58/111


Unbalanced Loading

Machines are assigned NPS current withstand values: Continuous NPS rating, I2R (PU CMR)

Short time NPS rating, I22t (K)

If possible level of system unbalance approaches machinecontinuous withstand, protection is required.

O l d P t ti


59/111


Overload Protection

high load current

heating of stator and rotor

insulation failure

Governor Setting

Should prevent serious overload automatically.

Generator may lose speed if required load can notbe met by other sources.

St t Th l P t ti


60/111


Stator Thermal Protection

Current operated

Over power protection Overcurrent element Thermal replica

RTD Thermal Probes

PT100 Platinum probes Embedded in machine

Alarm and trip thresholds for each RTD

O l d P t ti (1)


61/111


Current

Time

Overload Protection (1)

Thermal replica for stator overload protection

Current based on I1 and I2 Heating and cooling time constants Non-volatile memory thermal state

Alarm output

Rotor Earth Fa lt Protection


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Rotor Earth Fault Protection

Field circuit is an isolated DC system.

Insulation failure at a single point :

No fault current, therefore no danger

Increase chance of second fault occurring Insulation failure at a second point :

Shorts out part of field winding Heating (burning of conductor) Flux distortion causing violent vibration of rotor

Desirable to detect presence of first earth fault and givean alarm.



63/111



R

Exciter

Potentiometer Method

Required sensitivity approximately 5% exciter voltage.

No auxiliary supply required.

Blind spot - require manually operated push button tovary tapping point.



64/111



AC Injection Method

Brushless Machines

No access to rotor circuit Require special slip rings for measurement

If slip rings not present, must use telemetering techniques(expensive)

R

AC AuxiliarySupply



65/111



Brushless Machine

A brushless generator has an excitation system consisting of:

A main excitor with rotating armature and stationary fieldwindings

A rotating rectifier assembly, carried on the main shaft lineout

A controlled rectifier producing the d.c. field voltage for themain exciter field from the a.c. source (often a small `pilot`exciter)

Hence:

No brushes are required in the field circuit

All control is carried out in the field circuit of the main exciter Detection of rotor circuit earth fault is still necessary Based on dedicated rotor-mounted system that has a

telemetry link to provide an alarm/data

Generator Back Up Protection


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Generator Back-Up Protection

10 x

FL

with AVR

no AVR

Cycles

Full

Load


Typical use : Very or extremely inverse for LV machines Normal inverse for HV machines

Must consider generator voltage decrement characteristic for close-in faults.With reliable AVR system, conventional overcurrent relays may be used.

Otherwise, voltage controlled / restrained relays are required.

Generator Back Up Protection


67/111


Generator Back-Up Protection


Voltage Restrained

Operating characteristic is continuously varied depending onmeasured volts.

Alternatively, use impedance relay.

Voltage Controlled

Relay switches between fault characteristic and load characteristicdepending on measured volts.

F

Generator Back Up Protection (2)


68/111


10

O/L CHARAC

FAULT CHARAC1.0

t

sec

GENERATORDECREMENTCURVE

0.1

0.01100 AMPS10,00030001000600240

LARGESTOUTGOINGFEEDER

6.6kV

5MVA

115% XS

500/5

200/5

Generator Back-Up Protection (2)

Voltage Dependent Overcurrent


69/111


I>

Terminal Volts

LoadFault

k.I>

Voltage control

I>

Terminal Volts

LoadFault

k.I>

Voltage restraint

g pProtection (51V)

Impedance Rela


70/111


Impedance Relay

2 Zones of protection Zone 1 - Set to operate at 70% rated load impedance. Back-up

protection for generator-transformer, busbar and outgoing

feeders. Time delayed for co-ordination with external feederphase fault protection.

Zone 2 Set to 50% transformer impedance. Back-upprotection for generator phase faults. Faster time delay to co-ordinate with generator phase fault protection

R

X

Load

Fault

Underimpedance

Under & Over Frequency Conditions


71/111



Over Frequency

Results from generator over speed caused by sudden

loss of load. In isolated generators may be due to failure of speed

governing system.

Over speed protection may be provided by mechanical

means. Desirable to have over frequency relay with more

sensitive settings.



72/111



Under Frequency

Results from loss of synchronous speed due toexcessive overload.

In isolated generators may be due to failure of speed

governing system. Under frequency condition gives rise to:

Overfluxing of stator core at nominal volts

Plant drives operating at lower speeds - can affectgenerator output

Mechanical resonant condition in turbines

Desirable to supply an under frequency relay.

Protection may be arranged to initiate load shedding asa first step.

df/dt (81R)Loadshedding


73/111


df/dt+t: Time Delayed ROCOF

Df/dt can operate quicker than underfrequency for large changesin frequency

Rolling window is better than fixed window as gives fasteroperation

Averaging cycles is typically 5 to provide some stability for powersystem oscillations

Stages can be used for load shedding or alarm/tripping of thegenerator

Loadshedding

Under & Over Voltage Conditions


74/111



Protection

Under & over voltage protection usually provided as part

of excitation system. For most applications an additional high set over voltage

relay is sufficient.

Time delayed under and over voltage protection may be

provided.



75/111



Over Voltage

Results from generator over speed caused by suddenloss of load.

May be due to failure of the voltage regulator.

An over voltage condition :

Causes overfluxing at nominal frequency Endangers integrity of insulation

Under Voltage

No danger to generator. May cause stalling of motors.

Prolonged under voltage indicates abnormal conditions.

Generator Abnormal Frequency Protection(81AB)


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(81AB)

6 independent bands of abnormal frequencyprotection

Accumulation of time up to 1000 hours in eachband

Band data provided by generator manufacturer

Bands match resonance, blade stressfrequencies

Dead band timer before accumulation startsallows time for resonance to established

When generator is off-line bands can beblocked

Generator Abnormal Frequency Protection(81AB)


77/111


(81AB)

Band 1 f nom

Band 4

Band 3

Band 2

Timer 1

Timer 2

Timer 3

Timer 4

ApplicationN ti S O lt (47)


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Negative Sequence Overvoltage (47)

Generator/MotorCB

Negative Sequence Overvoltage

Swapping of 2 phases to motor (pump water)

47Generator/Motor

47

b

a

c

BlockCB Close

Busbar

Hydro machines can operate as

motors/pumps by swapping 2 phases

(phase rotation is reversed)

a

b

c

Use of Alternative Setting GroupsE l P d St U it


79/111


Generator differential

Under & over voltage

Under & over frequency

Reverse powerStator earth fault

Loss of excitation

Voltage dependent overcurrent

Negative phase sequence

87G

27 & 59

81U & 81O

32R51N

40

51V

46

When the units are being used to generatepower the protection could be as below:

When the units pump water the protection

applied will change

2 31 4

Four groups

available

32R Reverse power

Example : Pumped Storage Unit

Phase Rotation


80/111


Phase Rotation

Phase rotation for hydro generator/motor

applications where 2 phases are swapped tomake the machine operate as a pump (motor)

G x

P340

Phase

Reversal

Switches

CT1 CT2

Case 1 : Phase Reversal Switches affecting all CTs and VTs

G x

P343/4/5

PhaseReversal

Switches

CT1 CT2

Case 2 : Phase Reversal Switches affecting CT1 only

Phase Rotation


81/111


Phase Rotation

Phase rotation settings can be changed for

generator/motor operation using 2 setting groups

Setting Range Default

SYSTEM CONFIG

Phase Sequence Standard ABC /Reverse ACB

Standard ABC

VT Reversal No Swap /A-B Swapped /B-C Swapped /C-A Swapped

No Swap

CT1 Reversal No Swap /A-B Swapped /B-C Swapped /

C-A Swapped

No Swap

CT2 Reversal(P343/4/5 only)

No Swap /A-B Swapped /B-C Swapped /C-A Swapped

No Swap

Unintentional Energisation at Standstill


82/111


50

27

VTS

&

tPU

tDO

& Trip

Unintentional Energisation at Standstill

Overcurrent element detects breaker flashover orstarting current (as motor)

Three phase undervoltage detection

VTS function checks no VT anomalies

Check Synch (25)


83/111


Check is used when closing generator CB to ensure synchronism withsystem voltage.

Check synch relay usually checks 3 things:

Phase angle difference Voltage Frequency difference

Check Synchronising (25)


84/111


y g ( )

Phase angle difference

Single phase comparison Can select either A-N, B-N, C-N, A-B, B-C, C-A is settings

Typical setting is 20 to reduce mechanical stresses on generators.

Voltage

Check synch relay inoperative if :-

Generator/busbar voltage is below or above preset limit (independent settings

for generator and busbar under/overvoltages)

voltage difference exceeds preset limit

Typical settings for undervoltage: 80 - 85% Vn Typical settings for difference voltage: 6 - 10% Vn

Frequency difference

Usually measured by time to traverse phase angle limits or direct slipfrequency measurement (Fgen Fbus)

Eg Timer setting of 2 secs over20 :

Slip frequency = 2 x (20 x ) / 360 = 0.055Hz = 0.11% (50Hz)

Timer usually set to 2 secs or 10 x C.B. closing time whichever is greater).

Check Synchronising (25)


85/111


y g ( )

Check synch has 2 stages Check Sync 1/2

Usually only 1 stage is required for generator applications Check Sync 2 has CB closing time compensation

Check Sync2 only permits closure for decreasing angles of slip

Check synch has vector compensation to account for phaseshift across transformer with Main VT Vect Grp setting 0-11

Check synch has ratio correction to correct ratio errors of VTs

Voltage monitors for dead/live generator/busbar

System Split output operates for phase angle > settingadjustable from 90 to 175 degrees

Check Synch (25)


86/111


y ( )

Check synch stages 1 and 2


87/111

GRID

Technical Institute


transmitted by any means, copied, reproduced or modified without the prior

written consent of Alstom Grid Technical Institute. All rights reserved.

Typical Schemes

Protection Package for Diesel Generator


88/111


g

G87

R64

R64

V51

32

32 Reverse Power

64R Rotor Earth Fault

64S Stator Earth Fault

51V Voltage DependentOvercurrent

87G Generator Differential

Protection P343

Overall Protection of Generator Installation


89/111


GeneratorFeeder Protn.

51 V

64R

32

40

87

46

64S

OvercurrentVoltage Restraint

RestrictedE/F

BuchholzWinding Temp.

Reverse Power

Field Failure

Generator Differential

Rotor E/F Prime Mover Protection

Negative Phase Sequence

Stator E/F

OverallGen/TransDiffl Protn.

Overall Protection of Generator Installation


90/111


Generator FeederProtection

Low Steam Pressure, Loss of VacuumLoss of Lubricating OilLoss of Boiler Water

Governor Failure

Vibration, Rotor Distortion

O/C Circuit Breaker Fail

Busbar Protection

RestrictedE/F

Buchholz WindingTemperature

V.T.sO/CTransformerOverfluxing

RestrictedE/F

StandbyE/F

Buchholz

O/C + E/F

Unit TransformerDifferential Protn.

Overall GeneratorTransformer

Differential Protn.

Rotor E/F

Permissive(Low Power)

InterlockPole Slipping

Field Failure

Generator Differential

Negative Phase Sequence

Stator E/FProtection


91/111

GRID

Technical Institute


transmitted by any means, copied, reproduced or modified without the prior

written consent of Alstom Grid Technical Institute. All rights reserved.

Embedded Generation

Co-generation/Embedded Machines


92/111


PES

system

PES

system

81U/O

27/59

59N

df/dt

dV

Frequency

Voltage

Residual Voltage

81U/O

27/59

59NIslanded load

fed unearthed

AR?

O/C & E/F50/51N

df/dt

dVROCOF

Voltage Vector Shift

g

NPS Voltage

NPS O/C

47/46

Check Synch25

Embedded Generation


93/111


USED TO PROVIDE:

Emergency Power Upon Loss Of Main Supply

Operate In Parallel To Reduce Site Demand

Excess Generation May Be Exported Or Sold

Engineering Recommendation G59


94/111


ER G59 relates to the connection of generating plant tothe distribution systems of licensed distribution networkoperators (DNOs)

ER G83/1 covers connection of generating units rated

Documents

Generator Protn