generator protection system by nicholas naing

Index

This Seminar is Proudly Sponsored by :TRUST SYNERGY INTERNATIONAL

by Nicholas Naing

GENERATOR PROTECTION SYSTEM

Index

1.00 p.m : Welcome Speech by YTU Electrical Power Department Head

1.10 p.m : Introduction to the Speaker

1.15 p.m : Generator Protection Systems

1.50 p.m : Tea Break

2.00 p.m : Protection Functions Detail

2.40 p.m : Question and Answer Section

3.00 p.m : End of Presentation

Agenta : 13th JAN 2016 , 1 p.m ~ 3 p.m , YTU

IndexOverview Generator Abnormal Operating Conditions

Loss of SynchronismAbnormal FrequencyOver excitationField LossInadvertent EnergizingBreaker FailureLoss of Prime Mover PowerBlown VT FusesOpen Circuits

Index

The "Wild"PowerSystem

G

Exciter

Loss of FieldLoss of Field

Overexcitation

Overexcitation

Overexcitation

OpenCircuits

Loss ofSynchronism

InadvertentEnergizing,Pole Flashover

AbnormalFrequency

AbnormalFrequency

BreakerFailure

ReversePower

OverPower

What Really happened ?

IndexWhat Really happened ?

The "Wild"PowerSystem

G

Exciter

StatorGround

StatorPhase

SystemGround

SystemPhase

IndexProtection Functions

• Generator Stator Differential• Backup Distance Protection• 100% Stator Ground• Generator Unbalance• Loss of Excitation• Accidental Energization• Breaker Fail • Phase Overcurrent – Voltage Restraint• Neutral Inst. / Timed Overcurrent• Neg. Sequence Overcurrent• Under / Over Voltage• Under / Over Frequency• Generator Thermal Model• RTD Temperature• Overexcitation – Volts/Hertz

IndexSmall Generator Protection (IEEE)

32 Reverse Power

40 Loss of Excitation

51V voltage restraint

51G Ground overcurrent

87 Differential

Small Size – up to 1 MW

IndexMedium Generator Protection (IEEE)

Medium Size – up to 12.5 MW

32 Reverse Power

40 Loss of Excitation

46 Negative Sequence

51V voltage restraint

51G Ground overcurrent

87 Differential

IndexLarge Generator Protection (IEEE)

Large Size – Up to 50 MW

32 Reverse Power

40 Loss of Excitation

46 Negative Sequence

49 Thermal Overload

51V voltage restraint

51G Ground overcurrent

64 Ground Relay

87 Differential

IndexLarge Generator Protection (IEEE)

Large Size – above 50 MW

32 Reverse Power

40 Loss of Excitation

46 Negative Sequence

49 Thermal Overload

51V voltage restraint

51G Ground overcurrent

64 Ground Relay

87 Differential

IndexSample Generator Protection Relay Wiring

IndexSample Generator Protection Relay Wiring

IndexSample Generator Protection Relay Wiring

IndexSample Generator Protection Relay Wiring

Index

binary w. cable supervision inputs

Three-phase V AC(110-690V AC)

Three-phase I AC

MPU pickup/Dig. running/Ana. running

Crank Start prepare Run/stop coil

Three multi inputs: PT 100/1000, (0)4..20mA, VDO, 0..40V

Emergency stop

Start enable

Sample Generator Protection with Relay

Index

16 diesel generators15 diesel generators & 1 emergency generator8 bustie breakers2 shaft generators2 shore connectionsWrapped busbar possibillity

Sample Generators Parallel Setup

IndexBreak

IndexDesirable Attributes of Generator

Protection ANSI number Levels Standard

Phase sequence voltage 47 1 ×

Generator reverse power (2×) 32 2 ×

Generator overcurrent (4×) 50 4 ×

Voltage-dependent overcurrent 51V 1 ×

Fast overcurrent (2×) 51 2 ×

Generator overvoltage (2×) 59 2 ×

Generator undervoltage (3×) 27 3 ×

Generator overfrequency (3×) 81 3 ×

Generator underfrequency (3×) 81 3 ×

Busbar overvoltage (3×) 59B 3 ×

Busbar undervoltage (4×) 27B 4 ×

Busbar overfrequency (3×) 81B 3 ×

Busbar underfrequency (4×) 81B 4 ×

Generator overload (5×) 32 5 ×

Current/voltage unbalance 60 1 ×

Over excitation 24 1 ×

Loss of excitation 40 1 ×

Alarm relay 74 1 ×

Trip of non-essential load 3 3 groups

IndexGenerator Management Relay Sample

IndexProtection Functions

Generator Stator Differential (87)• Stator Phase Differential• Dual Slope Percent Restraint Operating

Characteristic • Directional Supervision under saturation

conditionsDistance Protection (21/21N)• set based in percentages of the line

impedances• zone 1 is 80% of the impedance of the

line in order to not reach the remote  end, the 

• zone 2 can be set at 120% of the impedance of the line in order to dependably  overreach the line, 

• zone 3 sometimes are disabled or set to cover an adjacent line.

IndexProtection Functions

Over Excitation ( 24 )

IndexProtection FunctionsVoltage Protection (59)

• Phase Overvoltage• Phase Undervoltage• Neutral Overvoltage (fundamental)• Neutral Undervoltage (3rd Harmonic)• Voltage Phase Reversal

Voltage Restraint OvercurrentUndervoltage Trip Curves

IndexProtection FunctionsCurrent Protection (50)

• Phase, Ground and Negative Sequence Overcurrent Tripping

• IEC, ANSI , IAC and Customizable Overcurrent Curves

• Voltage Restraint increasing sensitivity under low voltage conditions

IndexProtection Functions

Frequency Protection (81)• Overfrequency (81O)• Underfrequency (81U)

100% Stator Ground Protection (59N/59D)

Protects all of the stator windingExisting schemes typically only see 90%Stop low level fault near neutral from degrading into a high level fault and causing large amounts of damage

IndexProtection Functions

Reverse Power (32)Should be sensitive to 0.05 pu to properly detect motoring in large steam turbines

Existing E/M and Static relays not sensitive enoughMay cause shutdown difficulties

Negative Sequence (46)Should be sensitive to low values to detect open poles/conductors on system after

GSUExisting E/M and Static relays not sensitive enough

Long time low level events may cause excessive rotor heating, thermal tripping and damage rotor

IndexProtection FunctionsVolt/Hertz (Overexcitation) (40)

• Detects changes in the Volts/Hertz ratio of the generator or associated transformer

Loss of Excitation

Loss of Excitation (24)• Uses Impedance Circle for loss of excitation detection

• 2 Zones for fault detection and control

IndexProtection Functions

Thermal Protection (49 )• Generator Thermal Model• RTD Alarming and Tripping• RTD Biased Thermal Model

Thermal Model – Voltage Dependen Overload Curves

IndexProtection Functions

Inadvertent Energizing (27)

• High speed tripping of unit after breaker accidentally closed on dead machine, also pole flashover prior to syncing

• Most existing schemes do not incorporate• Many schemes fail due to complexity (reliance on breaker auxiliary switches, yard distance relays, etc.

• If breaker is not tripped rapidly, mechanical and electric damage can occur to machine in fractions of a second!

• Pole flashovers must be cleared by high speed breaker failure, as the breaker is open!

IndexProtection Relay Actions

IndexProtection Relay Actions

IndexCommon Problems

IndexContact Detail :

Nicholas Naing

naingwhbiz@gmail.com

#KoNaingYIT

Electrical Notes by Ko Naing YIT

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Index

THANK YOU