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


46 Negative Sequence



87 Differential

IndexLarge Generator Protection (IEEE)

Large Size – Up to 50 MW

32 Reverse Power



49 Thermal Overload



64 Ground Relay

87 Differential

IndexLarge Generator Protection (IEEE)

Large Size – above 50 MW

32 Reverse Power



49 Thermal Overload



64 Ground Relay

87 Differential

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


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.


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


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


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


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

Thermal Model – Voltage Dependen Overload Curves


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

IndexCommon Problems

IndexContact Detail :

Nicholas Naing

[email protected]

#KoNaingYIT

Electrical Notes by Ko Naing YIT

Index

THANK YOU

Generator protection system by nicholas naing

Engineering

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