Transcript Meeting the Challenges of the New Millennium:

Generator Management Relay
Protection, metering, and monitoring functions for generators.
Presented by:
John Levine, P.E.
Levine Lectronics and Lectric, Inc.
[email protected]
770 565-1556
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Outline
Overview
Theory
Wiring
Security
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What a Generator looks like
Generator Protection
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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 nondigital) 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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Generator Management Relay
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
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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
System
Ground
Stator
Ground
Exciter
G
The
"Wild"
Power
System
Stator
Phase
System
Phase
• Internal and External Short Circuits
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Generator Protection Review
– Abnormal Operating Conditions
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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
Over
Power
Overexcitation
Loss of Field
Open
Circuits
Loss of Field
Overexcitation
Overexcitation
The
"Wild"
Power
System
Exciter
G
Abnormal
Frequency
Reverse
Power
Inadvertent
Energizing,
Pole Flashover
Breaker
Failure
Abnormal
Frequency
Loss of
Synchronism
• Abnormal Operating Conditions
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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:
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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 & IAS
They are updated every 5 years
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Small Machine Protection
IEEE Buff Book
32 Reverse Power
40 Loss of Excitation
51V voltage restraint
51G Ground overcurrent
87 Differential
• Small – up to 1 MW to 600V, 500 kVA if >600V
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Small Machine Protection
IEEE Buff Book
32 Reverse Power
40 Loss of Excitation
46 Negative Sequence
51V voltage restraint
51G Ground overcurrent
87 Differential
• Medium – up to 12.5 MW
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Small Machine Protection
IEEE Buff Book
32 Reverse Power
40 Loss of Excitation
46 Negative Sequence
49 Thermal Overload
51V voltage restraint
51G Ground overcurrent
64 Ground Relay
87 Differential
• Large – up to 50 MW
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Large Machine Protection
IEEE C37.102
• Unit Connected,
• High Z
Grounded
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:
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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
Dual Slope Phase Differential
• Backup for primary line protection
• Configurable Reach and Angle Distance
Characteristic
100% Stator Ground Protection
• 95% Fundamental OverVoltage
• 15% Third Harmonic UnderVoltage
Two Zone Distance Backup
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Protection Functions
Voltage Protection
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Phase Overvoltage
Phase Undervoltage
Neutral Overvoltage (fundamental)
Neutral Undervoltage (3rd Harmonic)
Voltage Phase Reversal
Current Protection
Voltage Restraint Overcurrent
• 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
Undervoltage Trip Curves
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Protection Functions
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
Thermal Model – Voltage
Dependant
Overload Curves
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
Loss of Excitation
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Wiring
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Example
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Enhanced Security
Prevents Unauthorized Access and Provide Traceability
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)
• 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
Security strategy – conforms to industry and regulated guidelines
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