Upload
mojsic6313
View
223
Download
1
Embed Size (px)
Citation preview
8/20/2019 Webinars DL Protection System Fundamentals 060210
1/55
Power Plant and Transmission System
Protection CoordinationFundamentals
NERC Protection Coordination Webinar Series
June 2, 2010
Jon Gardell
8/20/2019 Webinars DL Protection System Fundamentals 060210
2/55
2 Agenda
Objective
Introduction to Protection
Generator and Power Plant Protection• Generator Basics
Unique Dynamic Characteristics of Generators
Generator and Auxiliary System Protection Requirements
• Generator Step-Up Transformer Basics
Protection Requirements
• Breaker Failure Basics
Protection Requirements
8/20/2019 Webinars DL Protection System Fundamentals 060210
3/55
3 Agenda
Transmission System Protection Basics
• Step Distance Principles
• Types of Relaying and Schemes Used
• Pilot and Communications
• Infeed
• Benefit of Using Pilot Schemes and Effect on
Coordination Issues
Pertinent IEEE Guides for Equipment andSystem Protection and References
8/20/2019 Webinars DL Protection System Fundamentals 060210
4/55
4 Agenda
Summary of What is Important to Coordination
Questions and Answers
8/20/2019 Webinars DL Protection System Fundamentals 060210
5/55
5Disclaimer
The information from this webcast is provided forinformational purposes only. An entity's adherence to theexamples contained within this presentation does notconstitute compliance with the NERC Compliance Monitoringand Enforcement Program ("CMEP") requirements, NERC
Reliability Standards, or any other NERC rules. While theinformation included in this material may provide some of themethodology that NERC may use to assess compliance withthe requirements of certain Reliability Standards, this materialshould not be treated as a substitute for the ReliabilityStandard or viewed as additional Reliability Standard
requirements. In all cases, the entity should rely on thelanguage contained in the Reliability Standard itself, and noton the language contained in this presentation, to determinecompliance with the NERC Reliability Standards.
8/20/2019 Webinars DL Protection System Fundamentals 060210
6/55
6Objective
Increase knowledge of recommended protection for
power plant and transmission system.
• Provide transmission protection engineers with insight into power
plant protection issues.
• Provide power plant protection engineers with insight into
transmission protection issues.
• Provide planning engineers with insight into how power plant and
transmission protection respond to system conditions.
Facilitate improved coordination between power plant
and transmission system protection.
8/20/2019 Webinars DL Protection System Fundamentals 060210
7/55
7Introduction to Protection
Reliability
Security
Dependability
Coordination
Electrical Protection Definitions can be found in
IEEE Dictionary Standard 100.
8/20/2019 Webinars DL Protection System Fundamentals 060210
8/55
8Generator and Power Plant Basics
Typical Steam Turbine
Generator found in a Power
Plant
8/20/2019 Webinars DL Protection System Fundamentals 060210
9/55
9
The Role of theGenerator in the Power System
Production of Electrical Energy to Meet Load
Demand and System Losses
Balance of Energy and Stability
Dynamic Behavior
Voltage Support
System Frequency
8/20/2019 Webinars DL Protection System Fundamentals 060210
10/55
10Balance of Energy and Stability
Power System Stability - “If the oscillatory
response of a power system during the transient
period following a disturbance is damped and
the system settles in a finite time to a newsteady operating condition we say the system is
stable. If the system is not stable, it is
considered unstable.”
8/20/2019 Webinars DL Protection System Fundamentals 060210
11/55
11Dynamic Behavior of Generators
Synchronous generators can adjust to changing
load conditions fairly readily.
For small load changes a generator easily can
adjust as long as there is a reserve capability.
Machine characteristics, excitation performance,
and the severity of the disturbance will dictate a
generator’s stability during large transientevents.
8/20/2019 Webinars DL Protection System Fundamentals 060210
12/55
12
Synchronous GeneratorEquivalent Circuit
Synchronous Generator Equivalent Circuit identifying armature reaction and
armature leakage reactance and air-gap voltage
Xarmature leakageX armature reaction
E excitation
R armature
X synchronous
V terminalE air gap
8/20/2019 Webinars DL Protection System Fundamentals 060210
13/55
13 Voltage Support
Generators on the system are used to maintain
voltage.
Automatic Voltage Regulators are set to meet a
scheduled system voltage and provide reactive
power support.
Generators provide system control by
maintaining terminal voltage during real andreactive power load changes.
8/20/2019 Webinars DL Protection System Fundamentals 060210
14/55
14System Frequency
Balance between generators and system loads.
System frequency is maintained through turbine
speed control.
Excessive load will bog down the system
frequency.
Light load conditions will increase systemfrequency.
8/20/2019 Webinars DL Protection System Fundamentals 060210
15/55
15
Unique Dynamic Characteristicsof Generators - Short Circuit Current Decrements
Time (Cycles)
5 10 15 20 25
2
4
6
8
10
12
14
00
Asymmetrical RMS Current
1
3
5
7
9
11
13
DC
Current
Symmetrical RMS Current
C u r r e n t i n A m p e r e s ( x 1 0 0 0 )
Reference: Fitzgerald, A. E. ,
Kingsley, Charles, and Umans,
Stephen, Electric Machinery,
fourth edition, McGraw-Hill Book
Company, New York, 1983.
8/20/2019 Webinars DL Protection System Fundamentals 060210
16/55
16
Power Plant EquipmentProtection Requirements
51T
87G
87T
21 32 40 46 51V 78
24 27 59 81
50/27
R
51G 51TG
50BF
59GN/27TH
87U
8/20/2019 Webinars DL Protection System Fundamentals 060210
17/55
17
Generator Fault and AbnormalOperating Conditions
Generator Faults
• Stator Phase
• Stator and Field Ground
Generator Step-up Transformer Faults
• Phase and Ground
System Back Up for Faults
• Phase and Ground
Abnormal Operating Conditions
• Over/undervoltage• Overexcitation
• Load Unbalance
• Loss-of-Field
• Loss-of-Synchronism (Out-
of-Step)
• Over/underfrequency• Loss of Prime mover
(Motoring)
• Inadvertent Energizing
• Breaker Failure
8/20/2019 Webinars DL Protection System Fundamentals 060210
18/55
18
Pertinent Power Plant Protection forCoordination Considerations
Phase Distance Protection (Function 21)
Overexcitation or V/Hz (Function 24)
Undervoltage Protection (Function 27)
• Generator Unit Protection
• High Side Protection Applied at Point of Common Coupling
• Generating Plant Auxiliary Power Supply Systems
Reverse Power Protection (Function 32)
Loss-of-Field Protection (LOF) (Function 40) Negative Phase Sequence or Unbalanced Overcurrent Protection
(Function 46)
Inadvertent Energizing Protection (Function 50/27)
Breaker Failure Protection (Function 50BF)
8/20/2019 Webinars DL Protection System Fundamentals 060210
19/55
19
Pertinent Power Plant Protection forCoordination Considerations
Backup Phase (Function 51T) and Backup Ground OvercurrentRelay (Function 51TG)
Voltage-Controlled or -Restrained Overcurrent Relay (Function 51V)
Overvoltage Protection (Function 59)
Stator Ground Relay (Function 59GN/64G)
Out-of-Step or Loss-of-Synchronism Relay (Function 78)
Over and Underfrequency Relay (Function 81)
Transformer Differential Relay (Function 87T), Generator Differential
Relay (Function 87G) Protection and Overall Differential Protection(Function 87U)
8/20/2019 Webinars DL Protection System Fundamentals 060210
20/55
20Phase Distance Protection (Function 21)
Distance protection to provide back-up protection forsystem faults that have not been cleared by transmissionsystem circuit breakers via their relays.
Impedance measurement derived from the quotient of
generator terminal voltage divided by generator statorcurrent.
• Machine Coverage
• System Relay Failure Coverage
Coordination Concerns – Undesired operation for systemconditions; especially stressed voltage situations andpower swings.
8/20/2019 Webinars DL Protection System Fundamentals 060210
21/55
21
Overexcitation or V/HzProtection (Function 24)
Protection measures a ratio of voltage to frequency at
the generator terminals.
Provides overexcitation protection for the generator and
any terminal connected transformers, i.e. GSU andauxiliaries.
Overexcited magnetic cores can lead to severe
overheating and breakdown in insulation.
Coordination Concerns – Coordinate withUnderfrequency Load Shedding (UFLS) programs in the
system.
8/20/2019 Webinars DL Protection System Fundamentals 060210
22/55
22
Undervoltage Protection (Function 27)Generator Unit Protection
Typically provides alarm and supervision for other
protection using generator terminal voltage. Rarely used
to trip the generator directly.
Provides detection of low voltage that may result inreduction in stability limit, excessive reactive power
drawn from the system, and malfunction of voltage
sensitive devices and equipment.
Coordination Concerns – Coordinate with any systemundervoltage protection, system fault conditions, and
stressed system voltage situations for which the system
is designed to survive.
8/20/2019 Webinars DL Protection System Fundamentals 060210
23/55
23
Undervoltage Protection (Function 27)High Side Protection at Point of Common Coupling
Protection measures system voltage at the pointof common coupling.
Provides a trip of the distributed resource on
undervoltage if it is islanded with local load or issubjected to a prolonged system fault.
Coordination Concerns – Coordinate with:
• Any system undervoltage protection,• System fault conditions and stressed system voltage
conditions for which the system is designed tosurvive.
d l ( 2 )
8/20/2019 Webinars DL Protection System Fundamentals 060210
24/55
24
Undervoltage Protection (Function 27)
Generating Plant Auxiliary Power Systems
Protection measures auxiliary system voltage.
Provides alarming or tripping, automatic transfer
to backup supply, starting emergency
generation.
Coordination Concerns – Coordinate with:
• Any system undervoltage protection,
• System fault conditions and stressed system voltage
situations for which the system is designed to survive.
8/20/2019 Webinars DL Protection System Fundamentals 060210
25/55
25
Concerns with Auxiliary SystemPower Supply Source
GSU
G
Au xi lia ry
BackupPowerSupply
27
PowerPlant
StationService
TrasferSwitch
System
GSU
G
Aux ili ary
27
Power Plant
Station
Service
Trasfer
Switch
System
System
Unit Auxiliary Transformer Supplied Scheme
Transmission System Transformer Supplied Scheme
8/20/2019 Webinars DL Protection System Fundamentals 060210
26/55
26Reverse Power Protection (Function 32)
Protection measures reverse power derived
from the real component of generator voltage
times generator stator current times the square
root of three. Provides protection of the prime mover from
damage due to motoring.
Coordination Concerns - None
f ld ( )
8/20/2019 Webinars DL Protection System Fundamentals 060210
27/55
27
Loss-of-Field (LOF) Protection(Function 40)
Protection measures impedance derived from the
quotient of generator terminal voltage divided by
generator stator current.
Provides detection and protection for complete or partialloss of the field excitation due to field winding open or
shorts, tripping of the field breaker, loss of supply, or
voltage regulation failure.
Coordination Concerns – Undesired operation duringsystem disturbances and system power swings that are
recoverable.
8/20/2019 Webinars DL Protection System Fundamentals 060210
28/55
28
Negative Phase Sequence orUnbalanced Overcurrent Protection (Function 46)
Protection measures stator negative sequence currentproduced by the unbalanced conditions of the system towhich the generator is connected.
Provides protection from excessive negative sequence
currents due to asymmetries, unbalanced loads,unbalanced system faults, and open phases. This cancause rotor component heating damage.
Coordination Concerns –
• Coordinate with system protection for unbalanced conditions.
• Awareness of continuous negative sequence level due to systemconditions and coordinate the continuous negative sequencecurrent protection or alarm such that it does not exceed thegenerator capability.
I d t t E i i P t ti
8/20/2019 Webinars DL Protection System Fundamentals 060210
29/55
29
Inadvertent Energizing Protection(Function 50/27)
Protection measures both generator terminal voltage andgenerator stator current to detect inadvertent energizingof the generator.
Provides detection of accidental energizing of an off-line
unit causing it to start-up as an induction motor.Significant damage can occur in a few seconds ofmachine motoring through the GSU transformer.
Coordination Concerns –
• Set point of the undervoltage supervision should be below 50
percent nominal voltage with at least a two second time delay.• Undesired tripping due to a higher set point should be avoided
during stressed system conditions and disturbances that can besurvived.
V lt C t ll d R t i d
8/20/2019 Webinars DL Protection System Fundamentals 060210
30/55
30
Voltage-Controlled or -RestrainedOvercurrent Protection (Function 51V)
Protection measures generator terminal voltage and
generator stator current. The current sensitivity varies
as a function of the terminal voltage.
Provides back-up protection for system faults when thepower system that the generator is connected to is
protected by time-current coordinated protection.
Coordination Concerns –
• Coordinate with system elements for faults.
• Not recommended when system protection is distance type
protection.
8/20/2019 Webinars DL Protection System Fundamentals 060210
31/55
31Overvoltage Protection (Function 59)
Protection measures generator terminal voltage.
Provides protection against generator
overvoltage. This prevents generator insulation
breakdown for sustained overvoltage.
Coordination Concerns – Coordinate with any
system overvoltage protection.
St t G d P t ti
8/20/2019 Webinars DL Protection System Fundamentals 060210
32/55
32
Stator Ground Protection(Function 59GN/64G, 27TH)
Protection measures the generator neutral zero
sequence voltage.
Provides protection for generator system ground
faults.
Coordination Concerns – Proper time delay is
required so that the protection does not trip due
to inter-winding capacitance issues for faults onthe system or instrument secondary grounds.
O t f St L f S h i
8/20/2019 Webinars DL Protection System Fundamentals 060210
33/55
33
Out-of-Step or Loss-of-SynchronismProtection (Function 78)
Protection uses a measurement of apparent impedance
derived from the quotient of generator terminal voltage
divided by generator stator current.
Provides loss-of-synchronism (out-of-step) protection forsystem swings that have electrical centers located near
the generator and its step-up transformer.
Coordination Concerns –
• Undesired operation during system disturbances.
• System power swings that are recoverable. Stability studies
need to be performed.
O d U d f P t ti
8/20/2019 Webinars DL Protection System Fundamentals 060210
34/55
34
Over and Underfrequency Protection(Function 81)
Protection measures voltage frequency to detect over
and underfrequency conditions.
Provides protection against sustained abnormal
frequency operation for the prime mover and generator. Coordination Concerns –
• Coordination is required with the system underfrequency load
shedding (UFLS) program and stressed system frequency
conditions for which the system is designed to survive.• The UFLS needs to take action first to arrest the abnormal
frequency condition.
G t Diff ti l P t ti (F ti 87G)
8/20/2019 Webinars DL Protection System Fundamentals 060210
35/55
35
Generator Differential Protection (Function 87G)and Overall Differential Protection (Function 87U)
Protection measures difference current in its
associated zone.
Provides high-speed phase fault protection for
the generator zone (87G) and unit overall zone(87U)
Coordination Concerns – None except to ensure
overlaps are done correctly.
8/20/2019 Webinars DL Protection System Fundamentals 060210
36/55
36Generator Step-Up Transformer Basics
GSU Transformer, Auxiliary Transformer and Isolated Phase Bus
B k Ph (F ti 51T) d B k
8/20/2019 Webinars DL Protection System Fundamentals 060210
37/55
37
Backup Phase (Function 51T) and BackupGround Overcurrent Protection (Function 51TG)
Protection measures GSU phase and neutral ground
current.
Provides back-up protection for faults in both the GSU
and generator, and for system faults. Coordination Issues –
• Coordinate with generator protection and the slowest system
protection.
• Use of the backup phase protection (Function 51T) is notrecommended due to the difficulty of coordinating with system
protection functions and the detection of faults due to the
generator fault current decrement.
Backup Phase Overcurrent
8/20/2019 Webinars DL Protection System Fundamentals 060210
38/55
38
Backup Phase OvercurrentProtection (Function 51T)
If function 51T is applied, it must be set to the followingrequirements:
• The 51T must have a minimum pickup of twice the generatorMVA rating at rated power factor.
• The 51T must operate slower with margin than the slowesttransmission protection system that it must coordinate withbased on protection design including breaker failure time.
• The 51T must sense the required fault based on thetransmission protection design with the fault current availablefrom the generator in the time frame that it is set to operate.
• The Generator Owner must determine that the setting for the51T that coordinates with the transmission protection will alsocoordinate with the generator protection systems for the faultcurrent available from the transmission system.
Backup Ground Overcurrent
8/20/2019 Webinars DL Protection System Fundamentals 060210
39/55
39
Backup Ground OvercurrentProtection (Function 51TG)
Function 51TG must be set to the following
requirements:
• The 51TG must have a pickup with margin greater
than the largest non-fault system unbalanceanticipated based on system design.
• The 51TG must operate slower with margin than the
slowest transmission protection system that it must
coordinate with based on protection design includingbreaker failure time.
Transformer Differential Protection
8/20/2019 Webinars DL Protection System Fundamentals 060210
40/55
40
Transformer Differential Protection(Function 87T)
Protection measures difference current in its
associated transformer zone.
Provides high speed phase fault protection for
the transformer zone (87T).
Coordination Concerns – None except to ensure
overlaps are done correctly.
8/20/2019 Webinars DL Protection System Fundamentals 060210
41/55
41Breaker Failure Basics
HV Substation Breaker
Breaker Failure Protection
8/20/2019 Webinars DL Protection System Fundamentals 060210
42/55
42
Breaker Failure Protection(Function 50BF)
Protection measures breaker current and monitors thebreaker “a” switch.
If the generator breaker does not clear the fault orabnormal condition in a specified time, the timer will tripthe necessary breakers to remove the generator fromthe system.
Coordination Issues –
• All upstream (next level) protection settings and systems mustbe considered when evaluating the performance of breaker
failure functions associated with generators.• Total clearing time, which includes breaker failure time, of each
breaker in the generation station substation should coordinatewith the critical clearing times associated with unit stability.
Breaker Failure Protection
8/20/2019 Webinars DL Protection System Fundamentals 060210
43/55
43
Breaker Failure Protection(Function 50BF)
8/20/2019 Webinars DL Protection System Fundamentals 060210
44/55
44Transmission System Basics
Types of Relaying and Schemes Used
Step Distance Principles
Pilot and Communications Infeed
Benefits of Using Pilot Schemes and
Effect on Coordination Issues
8/20/2019 Webinars DL Protection System Fundamentals 060210
45/55
45Types of Relaying and Schemes Used
Overcurrent (50, 51, 50N, 51N, 50G, 51G)
Directional Overcurrent (67, 67N)
Distance (21, 21N) Differential (87)
Step Distance
Pilot (Communication-Aided) Schemes
8/20/2019 Webinars DL Protection System Fundamentals 060210
46/55
46Step Distance Principles
Zones• Zone 1
• Zone 2
• Zone 3
8/20/2019 Webinars DL Protection System Fundamentals 060210
47/55
47Pilot and Communications
Pilot schemes use communication channels to send
data from the local protection terminal to the remote
protection terminal(s).
This information allows high-speed tripping to occur for
faults occurring on 100% of the protected line.
General Schemes Used:
• Transfer Trip
• Directional Comparison
• Current Differential
• Phase Comparison
8/20/2019 Webinars DL Protection System Fundamentals 060210
48/55
48Infeed
A source of fault current between a relay location and afault location.
Infeed has the effect of causing the relay to measure ahigher impedance than the actual impedance betweenthe relay and the fault location.
The method of calculating the effect of infeed (alsoknown as apparent impedance) is akin to a currentdivider relationship of two circuit paths in parallel.
• The positive sequence equivalent diagram for the example is
shown on the next slide.• The model combines impedances behind the faulted line.
• The generator impedance relay measures the quotientVgen/Irelay
8/20/2019 Webinars DL Protection System Fundamentals 060210
49/55
49Current Infeed Example Calculation
Xline
(Xsys Bus A + XL1)//(Xsys Bus C + XL2)= XB
X A = X’d + XTR
Vgen =
Vrelay
I A =Irelay
IB
I A + IB
I = I A + IB I
IB
I A
XB
X A
XLine
Restating I in terms of I A and recognizing
the current divider relationship of the
impedance branches:
Re
Re
Re
Re
Re
B A
A B
B A A
B
B Alay A TR A Line
B
lay A
lay B Alay TR Line
lay B
X I I
X X
X X I I
X
X X V I X I X X
I I
V X X Z X X
I X
=
+
+=
+= +
=
+= = +
Benefits of Using Pilot Schemes and
8/20/2019 Webinars DL Protection System Fundamentals 060210
50/55
50
Benefits of Using Pilot Schemes andEffect on Coordination Issues
Provides high-speed fault clearing.
Impacts on dependability and security are dependent on
the type of Pilot Scheme implemented.
These factors are related and require a balance.
Power Plant to Transmission System Protection
Coordination could benefit from the use of Pilot Schemes
due to higher speed and more selective operation.
Communication back to the plant system would also
benefit the coordination.
Pertinent IEEE Guides for
8/20/2019 Webinars DL Protection System Fundamentals 060210
51/55
51
Pertinent IEEE Guides forEquipment and System Protection
IEEE Std. C37.91-2008 – IEEE Guide for Protecting Power Transformers
IEEE Std. C37.96-2000 – IEEE Guide for AC Motor Protection
IEEE Std. C37.101-2006 – IEEE Guide for AC Generator GroundProtection
IEEE Std. C37.102-2006 – IEEE Guide for Generator Protection
IEEE Std. C37.106-2005 – IEEE Guide for Abnormal FrequencyProtection for Power Generating Plants
IEEE Std C37.113-1999(R2004) – IEEE Guide for Protective Relay Applications to Transmission Lines
IEEE Std. C37.119-2005 – Guide for Breaker Failure Protection ofPower Circuit Breakers
IEEE Std. 242-2001 – IAS Buff Book – Protection and Coordination
8/20/2019 Webinars DL Protection System Fundamentals 060210
52/55
52References
IEEE Press Book - Protective Relaying for PowerSystems: Volume 1, 1980.
IEEE Press Book - Protective Relaying for PowerSystems: Volume 2, 1992.
J. Lewis Blackburn, “Protective Relaying: Principles and Applications”, Marcel Dekker, Inc., 1987.
S. Horowitz and A. Phadke, “Power System Relaying”,John Wiley & Sons, Inc., 1992.
A. E. Fitzgerald, Charles Kingsley, Jr., Stephen D.Umans “Electric Machinery”, McGraw-Hill BookCompany, 1983.
f
8/20/2019 Webinars DL Protection System Fundamentals 060210
53/55
53References
C. R. Mason, “The Art and Science of Protective Relaying”, Wiley,1956.
Westinghouse Electric Corporation, “Applied Protective Relaying”,Westinghouse , 1982.
IEEE/PSRC Working Group Report, “Application of Multifunction
Generator Protection Systems,” IEEE Transactions on PowerDelivery, Vol. 14, No. 4, Oct 1999, P 1285-94.
Patel, S. C., Chau, N. H. and Gardell, J. D., “Upgrading andEnhancing the Generator Protection System By Making Use ofDigital Systems,” 24th Annual Western Protective Relay ConferenceOct 21 - Oct 23, 1997.
Yalla, M.V.V.S., “A Digital Multifunction Protective Relay,” IEEETransactions on Power Delivery, Vol. 7, No. 1, pp. 193-200, January1992.
What is Important to
8/20/2019 Webinars DL Protection System Fundamentals 060210
54/55
54
What is Important toCoordination – Summary
Distance Protection – Time Coordination, Loadability, and
Power Swings
Overcurrent Protection – Time-Current Coordination andLoadability
Voltage Protection – Time-Voltage Coordination and stressed
system voltage conditions for which the system is designed tosurvive
Volts per Hertz and Frequency Protection – Coordinate withUnderfrequency Load Shedding and stressed systemfrequency conditions for which the system is designed tosurvive
Loss of Excitation and Loss of Synchronism – Coordinate withsystem disturbances and system power swings that arerecoverable
Generator Breaker Failure – Total and Critical Clearing Times
8/20/2019 Webinars DL Protection System Fundamentals 060210
55/55
55
Question & Answer
Contact:
Phil Tatro, System Analysis
and Reliability Initiatives
508.612.1158
mailto:[email protected]:[email protected]