IEEE Generator Protection
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Transcript of IEEE Generator Protection
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Generator Management Relay
Protection, metering, and monitoring functions for generators.
Presented by:
John Levine, P.E.Levine Lectronics and Lectric, Inc.
[email protected] 565-1556
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Outline
Overview
Theory
Wiring
Security
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Generator Protection
What a Generator looks like
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Generator Protection
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Overview
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Why Upgrade? Generator and Transformer
• Existing generator and transformer protection (more than 5 years or non-digital) may:– Cause protection security issues
• Tripping on through-faults, external faults, swings, load encroachment and energizing
– May lack comprehensive monitoring and communications capabilities• Not provide valuable forensic info that can lead to rapid restoration
– Not be up to ANSI/IEEE Standards!– Insurance, Asset Reliability and Personal Liability Issues
• C37-102: Guide for the Protection of Synchronous Generators
• C37.91: Guide for Transformer Protection
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Product Overview• Ideal Protection for Induction and
Synchronous Generators at 25, 50 and 60Hz
• Complete Generator Protection including:
• Generator Stator Differential
• 2 or 3 Zone Distance Backup
• 100% Stator Ground
• High speed sampling, 12 samples per cycle
• Drawout Case Installation
• Powerful Fault Recording: Waveform, Sequence of Events
• Ethernet and Serial Communications
• Metering of all important parameters
Generator Management Relay
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Theory
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Show Generator Theory General Overview and Typical System from Training CD
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Generator Protection
• Internal and External Short Circuits
The "Wild"PowerSystem
G
Exciter
StatorGround
StatorPhase
SystemGround
SystemPhase
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Generator Protection Review
– Abnormal Operating Conditions• Loss of Synchronism
• Abnormal Frequency
• Overexcitation
• Field Loss
• Inadvertent Energizing
• Breaker Failure
• Loss of Prime Mover Power
• Blown VT Fuses
• Open Circuits
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Generator Protection
• Abnormal Operating Conditions
The "Wild"PowerSystem
G
Exciter
Loss of FieldLoss of Field
Overexcitation
Overexcitation
Overexcitation
OpenCircuits
Loss ofSynchronism
InadvertentEnergizing,Pole Flashover
AbnormalFrequency
AbnormalFrequency
BreakerFailure
ReversePower
OverPower
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IEEE PSRC Survey
– Conducted in early ’90s, showed many areas of protection lacking
– Unwillingness to upgrade:• Lack of expertise
– To recognize deficiency
– To perform the work
• “Generators don’t trip” (wrong)
• Operating procedures will save the day
PSRC = Power System Relay Committee
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ANSI/IEEE Standards
• Latest developments reflected in:– Std. 242: Buff Book
– C37.102: IEEE Guide for Generator Protection
– C37.101: IEEE Guide for AC Generator Ground Protection
– C37.106: IEEE Guide for Abnormal Frequency Protection for Power Generating Plants
These are created/maintained by the IEEE PSRC & IASThey are updated every 5 years
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Small Machine Protection IEEE Buff Book
• Small – up to 1 MW to 600V, 500 kVA if >600V
32 Reverse Power
40 Loss of Excitation
51V voltage restraint
51G Ground overcurrent
87 Differential
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Small Machine Protection IEEE Buff Book
• Medium – up to 12.5 MW
32 Reverse Power
40 Loss of Excitation
46 Negative Sequence
51V voltage restraint
51G Ground overcurrent
87 Differential
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Small Machine Protection IEEE Buff Book
• Large – 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
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• Unit Connected,
• High Z Grounded
Large Machine ProtectionIEEE C37.102
32 Reverse Power
40 Loss of Excitation
46 Negative Sequence
49 Thermal Overload
51V voltage restraint
51G Ground overcurrent
64 Ground Relay
87 Differential
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HYBRID SYSTEM
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Protection Functions
Protection Functions Include:
• 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
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Generator Protection
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Generator Protection with GSU Wrap PTs on Low Side
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Generator Protection with GSU Wrap PTs on High Side
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Generator Protection PTs on Low Side
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Desirable Attributes - Generator
– 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 enough
– May cause shutdown difficulties
– Negative Sequence (46)• Should be sensitive to low values to detect open poles/conductors on system after GSU
– Existing E/M and Static relays not sensitive enough
• Long time low level events may cause excessive rotor heating, thermal tripping and damage rotor
– 100% Stator Ground (59N / 59D)• Protects all of the stator winding
– Existing schemes typically only see 90%
– Stop low level fault near neutral from degrading into a high level fault and causing large amounts of damage
– Very secure
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Desirable Attributes - Generator
• Inadvertent Energizing (50/27)
– 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!
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Line – Ground faults – Delta Connected Generator
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Line – Ground faults – Wye Connected Generator
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Protection Functions
Generator Stator Differential• Stator Phase Differential• Dual Slope Percent Restraint Operating
Characteristic • Directional Supervision under saturation
conditions
Distance Backup Protection• 2 or 3 Zone Mho Distance Protection• Backup for primary line protection• Configurable Reach and Angle Distance
Characteristic
100% Stator Ground Protection• 95% Fundamental OverVoltage• 15% Third Harmonic UnderVoltage
Dual Slope Phase Differential
Two Zone Distance Backup
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Protection Functions
Voltage Restraint Overcurrent
Undervoltage Trip Curves
Voltage Protection• Phase Overvoltage• Phase Undervoltage• Neutral Overvoltage (fundamental)• Neutral Undervoltage (3rd Harmonic)• Voltage Phase Reversal
Current Protection • Phase, Ground and Negative Sequence Overcurrent Tripping
• IEC, ANSI , IAC and Customizable Overcurrent Curves
• Voltage Restraint increasing sensitivity under low voltage conditions
Frequency Protection• Overfrequency• Underfrequency
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Protection Functions
Loss of Excitation
Thermal Protection• Generator Thermal Model• RTD Alarming and Tripping• RTD Biased Thermal Model
Inadvertent Energization • Prevents Accidentally Closing a Stopped Generator onto a Live Line
• Armed when Generator is Offline and Voltage is below a pre-set level
Loss of Excitation (show Training CD)
• Uses Impedance Circle for loss of excitation detection• 2 Zones for fault detection and control
Volt/Hertz (Overexcitation)• Detects changes in the Volts/Hertz ratio of the generator or associated transformer
Thermal Model – Voltage Dependant Overload Curves
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Wiring
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Example
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Security Audit Trail
• Date and time of hardware, firmware or setting changes to your relays
• Logging of the MAC address of computers and users making settings changes
• Track method of how settings changes were made (i.e. keypad, serial port, ethernet)
Security strategy – conforms to industry and regulated guidelines
• Date/time security report was generated
• Description of the GE Multilin Relay
• Summary of the last time the configuration was changed
• History of last 10 occurrences the configuration was changed
Enhanced Security
Prevents Unauthorized Access and Provide Traceability