PROTECTIVE RELAYING & COMMUNICATIONS€¢ Power Circuit Breakers ... POWER CIRCUIT BREAKER: 345 KV...
Transcript of PROTECTIVE RELAYING & COMMUNICATIONS€¢ Power Circuit Breakers ... POWER CIRCUIT BREAKER: 345 KV...
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PROTECTIVE RELAYING & COMMUNICATIONS
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TOPICS
• The Power System
• Components
• Protection Principles
• Protection System Components
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TOPOLOGY OF TYPICAL
POWER SYSTEM
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POWER SYSTEM COMPONENTS
• Generators (Alternators)
• Power Transformers
• Bus
• Transmission Lines
• Power Circuit Breakers (Live Tank & Dead Tank)
• Circuit Switchers
• Disconnect Switches (Manual & Motor Operated)
• Reactors (Shunt & Series)
• Capacitors (Shunt & Series)
• HVDC (High Voltage Direct Current)
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GENERATORS: LARGE
STEAM TURBINE
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GENERATORS: WIND TURBINE
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GENERATORS: HYDRO-ELECTRIC
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GENERATORS: OTHERS
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TRANSFORMER:
1Φ, 115/10 VOLT, 5 VA
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TRANSFORMER:
3Φ 345/230/13.8 KV 600 MVA
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BUS: PIPE, BAR,
OR STRANDED CONDUCTOR
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TRANSMISSION LINES: 345 KV
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POWER CIRCUIT BREAKER:
230 KV OIL
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POWER CIRCUIT BREAKER:
230 KV GAS (SF6)
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POWER CIRCUIT BREAKER:
345 KV AIR BLAST
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POWER CIRCUIT BREAKER:
345 KV AIR BLAST
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POWER CIRCUIT BREAKER:
345 KV GAS (SF6)
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OTHER POWER CIRCUIT
BREAKERS
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CIRCUIT SWITCHER & RL
SWITCHER
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DISCONNECT SWITCHES
345 KV MOTOR OPERATED 230 KV MANUAL OPERATED
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REACTORS: 3Φ 13.8 KV,
50 MVAR SHUNT
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REACTORS: THREE 1Φ 525 KV,
82.7 MVAR SHUNT
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REACTORS: THREE 230 KV,
1200 A, 40Ω SERIES
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CAPACITORS: SHUNT
USED TO
INCREASE SYSTEM
VOLTAGE &
IMPROVE POWER
FACTOR
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CAPACITORS: SERIES
Used to reduce transmission line impedance
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HVDC (HIGH VOLTAGE
DIRECT CURRENT)
The use of high voltage electronics allows direct current power transmission and other
applications: SVC, STATCOM, SSSC, connecting asynchronous ac power systems. Protective
relaying is done by the control system.
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SCHEMATIC REPRESENTATION
GENERATOR TRANSFORMER BUS
POWER CIRCUIT BREAKERS
BUSTRANSMISSION
LINE
TRANSMISSION
LINE
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WHY ARE PROTECTIVE
RELAYS NECESSARY?
• Faults in electrical circuits are always possible• Three-phase circuits can experience a variety of fault types
– Single-phase-to ground (most common type)– Phase-to-phase– Phase-to-phase-to ground– Three-phase– Open conductors
• Faults are caused by– Electrical insulation failure– Lightning strikes, strong wind, ice accumulation,
contact by foreign objects• Elevated current & arcs (>3000°f) cause equipment damage
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PROTECTION SYSTEM
COMPONENTS
• Measuring devices (instrument transformers)
– Current transformers (CTs): most important measurement
– Potential or voltage transformers (VTs, CCVTs)
• Power circuit breakers
• Circuit switchers
• Motor operated disconnect switches
• Protective relays or protection systems
• Teleprotection equipment
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CURRENT TRANSFORMERS (CTs)
• Reduce large currents (thousands of amperes) to safe levels for instruments (5 amperes nominal).
• Are designed to accurately scale down the magnitude and phase of primary currents. Multi-ratio units have taps.
• Function similar to ideal current sources.
• Bushing current transformers are placed around the high voltage bushings of equipment like generators, transformers and power circuit breakers.
• Free-standing current transformers are separate high voltage devices that are connected to buses and lines.
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BUSHING CURRENT
TRANSFORMERS
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BUSHING CURRENT
TRANSFORMERS
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FREE-STANDING CURRENT
TRANSFORMERS
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VOLTAGE TRANSFORMERS
(VTs & CCVTs)
• Reduce large voltages (10s to 100s of kilovolts) to safe levels for instruments (≈ 115 volt
nominal).
• Are designed to accurately scale down the magnitude and phase of primary voltages. Many provide two ratios.
• CCVTs are also used to couple high frequency power line carrier signals on to power lines.
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VOLTAGE TRANSFORMERS:
345 KV
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CAPACITOR VOLTAGE
TRANSFORMERS: 345 KV
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PROTECTIVE RELAYS
• IEEE definition of a protective relay: an electric device that is designed to interpret input conditions in a prescribed manner and after specified conditions are met to respond to cause contact operation or other similar abrupt change in associated electric control circuits. Inputs are usually electric, but may be mechanical, thermal, or other quantities.
• Have evolved over time as technology has advanced: electromechanical, solid state, microprocessor. Most protection functions are the same: different technology.
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ELECTROMECHANICAL
PROTECTIVE RELAYS
• Operate on the principles of electromagnetic attraction and induction using power system voltages and currents.
• Logical functions can be performed using combinations of series and parallel contacts.
• Each function usually requires a discrete device, which must be wired to other devices to implement logic.
• Electromechanical “targets” for post-operation analysis
• Rapidly being replaced by newer technology.
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ELECTROMECHANICAL
PROTECTIVE RELAYS
ELECTROMECHANICAL TRANSMISSION LINE PROTECTION
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SOLID STATE PROTECTIVE RELAYS
• Convert ac current and voltage input signals from instrument transformers into dc levels and square waves. Use solid state timers and logic gates to measure power system conditions and respond with contact or solid state outputs.
• Small scale integration (SSI) of electronics and modular circuit boards allow more functions to be incorporated into less control panel space.
• Much less wiring between protective devices is required since much of it is done on the foil traces of printed circuits
• LCD displays and LEDS for post-operation analysis.
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SOLID STATE PROTECTIVE RELAYS
SOLID STATE TRANSMISSION LINE PROTECTION
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MICROPROCESSOR
PROTECTIVE RELAYS
• Ac current and voltage input signals from instrument transformers are digitized by analog to digital converters. Microprocessors use algorithms to measure power system conditions and respond with contact or solid state outputs.
• Continuous self-diagnostics raise alarms if problems are detected within the protection system.
• Large scale integration (LSI) of electronics and modern fast, powerful microprocessors allow an incredible number of functions to be incorporated into very little control panel space.
• Virtually no wiring between protective devices is required.• Extensive data recording capability: oscillography and sequence of
events for post operation analysis.• Also called numerical protective relays. Perform so many functions
are more correctly called protection systems.
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MICROPROCESSOR
PROTECTIVE RELAYS
COMPLETELY REDUNDANT LINE PROTECTION
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TELEPROTECTION EQUIPMENT
• Teleprotection equipment is used with protective relays primarily for transmission line and breaker failure protection schemes.
• These functions require high speed (≈ 4 millisecond back-to-back operate time), high dependability, and security against incorrect operation.
• Equipment used to carry teleprotection signals include metallic cable (short transmission lines), power line carrier, analog microwave, digital microwave, leased telephone lines, fiber optic cable, and spread spectrum radio.
• Modern microprocessor based transmission line protection systems can be equipped with a variety of built-in communication hardware to interface with the relay at the other terminal: RS232, RS422, G.703, IEEE C37.94 fiber optic, 820 or 1300 nm multi-mode fiber optic, and 1300 or 1550 nm single-mode fiber optic.
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TELEPROTECTION EQUIPMENT
• The IEEE C37.94 standard defines a point-to-point optical link for synchronous data between a multiplexer and a teleprotection device. Data is usually 64 kbps but the standard allows for speeds up to 64n kbps, where n = 1, 2,F,12.
• IEEE C37.94 fiber optic interface can be used on multi-mode direct fiber for short-haul applications (up to 2 km) or with C37.94 compliant digital multiplexers for long distance transport.
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TELEPROTECTION EQUIPMENT
• Fiber optic communications is an excellent application for communications within and between electric power substations because it is immune to electromagnetic interference and ground potential differences.
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NEW
SALEM(ND_L4)
CAPITAL
HILL(ND_L1)
MANDAN(ND_L3)
BISMARCK(ND_L2)
WISHEK(IMCS_L23)
SOLEN(IMCS_L1)
WESTFIELD(IMCS_L2) FORBES
(IMCS_L22)
MOUND
CITY(IMCS_L3)
LOWRY(IMCS_L4)
LEOLA(IMCS_L21)
GETTYSBURG(IMCS_L5)
ABERDEEN(IMCS_L20)
HURON(IMCS_L13)
BROADLAND(IMCS_L12)
ALPENA(IMCS_L11)
FT.THOMPSON(IMCS_L8)
HIGHMORE(IMCS_L7)
CRANDALL(IMCS_L17) WALLACE
(IMCS_L16)
WATERTO
WN
BASIN(IMCS_L15a)
(IMCS_L15b)
CROW
LAKE(IMCS_L9)
STORLA(IMCS_L10)
GROTON(IMCS_L18)
SOUTH DAKOTA
NORTH DAKOTA
ORDWAY(IMCS_L19)
ORIENT(IMCS_L6)
ANGORA
SIDING(IMCS_L24)
CLARK(IMCS_L14)
21.68
26.72
26.891.36
6.95
23.10
28.53
35.98
28.64
28.94
22.02
36.97
27.64
15.45
37.31
21.25
21.51
20.82
2.52
36.50
36.
10
23.94
23.93
15.07
13.77
10.75
38.69
22.94
43.19
43.06
P1
P2
P3
P4
P8
P36
P37
P38
P39
P40
P41
P42
P43
P44
P45
P46
P47
P48
P49
P
5
0
P51
P52
P53
P54
P55
P56
P57
P58
P59
P60
(NNESET
D_L19)MINOT SW(ND_L13)
LOGAN(ND_L12)
BENEDICT(ND_L10)
UNDERWOOD(ND_L9)LOS
(ND_L7)
FT.CLARK(ND_L8)
TAYLOR(ND_L29)
AVS(ND_L6a)
(ND_L6b)GREEN
RIVER(ND_L28)
WILLIAMS(ND_L24)
CHARLIE
CREEK(ND_L27)
WILLISTON
(WAPA) (ND_L22)
EAST RAINY
BUTTE(ND_S3)
COLUMBUS(ND_L18)
KILLDEER
MOUNTAIN (ND_L26)
BELDEN(ND_L15)
BLAISDELL(ND_L16)
21.91
26.85
42.00
29.08
27.92
25.26
12.59
20.17
38.6
20.94
32.59
22.96
6.98
25.74
Belfield
67
41
P6
P7P5
P9
P10
P11
P12
P14
P16
P20
P27
P22
P18
P30
P31
P33
P34
P32
WILLISTON
(BASIN) (ND_L23)
P26
9.96
BERTHOLD(ND_L14)
KENASTON (ND_S1)
KENMARE (ND_S2)
Existing Microwave Site
New Microwave Site 2012-2014
Existing Microwave Hop
New Microwave Hop 2012-2014
Existing Microwave Hop (to be replaced)
Fiber Optic Path
Substation Location
RHAME
(ND_S4)
GLEN
ULLIN(ND_L5)
WHEELO
CK (ND_L20)
PIONEER(ND_L21)
30.7
P23
Map Updates 03/14/2017 JAB
LONESOME
CREEK(ND_L25)
New Microwave Tower Information:
Site Name Coordinates (DMS) Tower Height (feet)*
Berthold 48-19-34.35 101-45-35.3 250
Blaisdell 48-20-58.46 102-04-40.31 290
Columbus 48-46-25.3 102-46-04.10 290
Daglum 46-39-27.9 103-04-22.0 60 (Monopole)
Groton 45-22-26.8 98-06-11.3 100 (Monopole)
Judson 48-08-56.00 103-46-15.70 120 (Monopole)
Kenaston 48-37-54.3 102-06-20.9 100 (Monopole)
Kenmare 48-40-34.30 102-06-15.2 150(Monopole)
Kummer Ridge 47-47-55.69 102-55-43.85 290
Lonesome Creek 47-47-38.0 103-34-40 290
Minot SW 48-07-33.68 101-21-44.06 190
Neset 48-24-30.5 102-51-39.8 290
Niobe 48-38-31.4 102-18-12.4 190
Patent Gate 47-51-59.97 103-28-12.62 190
Pioneer 48-13-56.99 103-57-09.99 150
PW1 47-56-2.9 101-14-50.7 125 (Monopole)
Roundup 47-24-35.57 102-45-50.18 190
Squaw Gap Rptr 47-31-55.0 103-51-41.4 290
Squaw Gap Sub 47-32-43.49 103-49-46.17 120 (Monopole)
Underwood 47-26-53.5 101-07-12.90 150
Wheelock 48-20-23.37 103-18-18.51 290
* All towers are self supporting except Daglum, Groton, Kenmare, Kenaston, Judson, Richland MW,Squaw Gap Sub and PW1
P15
P21
P19
35.95
25.43
23.94 PW1(ND_L11)
P13
NIOBE(ND_L17)
22.7
9.4
9.4
22.7
P17
7.8
12.81
WTO
WAPA RPTR
Equipment in Cabinet
Squa
w Gap
Rptr
Pate
nt
Gat
e
Kum
mer
Ridge
Roundu
p
Juds
on Mall
ard
New Microwave Hop 2015-
2016
New Microwave Site 2015-
2016
Squa
w Gap
Sub
22
.5
9
29.
39
1.7
6
2
5
.
5
72
0.
0
8
9.02
1
9
.
0
7
13
.5
1
1
.
9
9
10
.0
9
7.
0
1
DAGL
UM
1
0
5.0
6
Richland
MW 20.
15
New Path 2017
Lewis &
Clark
Richland Sub
2
.
6
TAN
DE
1
4
.
2
9
1
7.
1
7
1
0
Rhame
Sub
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PROTECTION FUNCTIONS
• ANSI /IEEE standard C37.2 standard for electrical power system device function numbers, acronyms, and contact designations
• 21 - Distance relay• 46 - Reverse-phase or phase-balance current relay• 50 - Instantaneous overcurrent relay• 51 - AC inverse time overcurrent relay• 59 - Overvoltage relay• 67 - AC directional overcurrent relay• 87 - Differential protective relay• Ninety-nine different defined functions
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51 - OVERCURRENT FUNCTION
• As current magnitude increases operating time decreases.
• When a short circuit occurs on a power system element the current it draws greatly increases.
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21 - DISTANCE FUNCTION
• Distance functions operate on the impedance plane plotted using the R & X axis.
• They possess a characteristic shape that defines the border of the operate and restraint regions.
• The mho circle is one of the most commonly used shapes in protective relaying. Other shapes like the quadrilateral are also used. Transmission line protection is a common application.
• When a short circuit occurs on a power system element the impedance measured by its protective relay changes suddenly and dramatically.
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21 - DISTANCE FUNCTION
MHO CHARACTERISTIC QUADRILATERAL CHARACTERISTIC
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21 - DISTANCE FUNCTION
21LINE
F1 F2
THREE-ZONE
STEPPED
DISTANCE
SCHEME
21
-3
21
-2
21
-1
21
-1
21
-2
21
-3
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21 - DISTANCE FUNCTION
R
X
LINE IMPEDANCE
LOAD IMPEDANCE
FAULT IMPEDANCE
RESTRAINT REGION
OPERATE
REGION
Z = E / I
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87 - DIFFERENTIAL FUNCTION
• Operates on the difference of two quantities
• Current differential protection widley used on generators buses, transformers, reactors, and short transmission lines
• Current differential protection operates on the principal of Kirchoff’s current law: Σ i = 0
• Voltage differential is used on capacitor banks
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87 - DIFFERENTIAL FUNCTION
(CURRENT)
GENERATOR
TRANSFORMER BUS BUSTRANSMISSION
LINE
LINELOAD CURRENT
Σ I = 0
87
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BASIC OBJECTIVES OF
PROTECTIVE RELAYING
• Reliability
• Selectivity
• Speed
• Simplicity
• Economy
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RELIABILITY
• Protection systems spend 99.9% of their service time monitoring power system elements and very little of it operating so they must work when called on.
• Periodic testing of protective relays is done to verify that they are functioning properly.
• Electromechanical and solid state protective relays provided no indication that they had failed until they incorrectly operated. Microprocessor relays use self-diagnostics that will alarm on many failures.
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SELECTIVITY
• Maximizes continuity of service for power system elements.
• When faults do occur the minimum amount of high voltage equipment must be disconnected: only that required to isolate the fault.
• Prevents larger, cascading power outages.
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SPEED
• Quick clearing of faults minimizes damage and enhances power system stability.
• Modern EHV protection system equipment can clear a fault in less than four cycles (.067 seconds). Human eye blink = 0.100 - 0.400 seconds.
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SIMPLICITY
• Utilizing the minimum amount of equipment and the simplest schemes to provide protection saves time and money and maximizes the odds of a scheme working correctly.
• K.I.S.S. (Keep it simple)
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ECONOMICS
• Minimum total cost is important for everyone that uses electricity. Cheap electricity enhances a nation's prosperity.
• With their greatly increased capabilities and smaller size modern protection systems are a bargain compared to legacy (electromechanical & solid state) systems.
• Fully optioned modern transmission line protection systems can be purchased for $10k to $15k. They are extremely versatile and can do practically anything the protection engineer desires.
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ZONES OF PROTECTION
• Are defined by the locations of current transformers.
• Allow protection systems to isolate only the faulted element.
• Will discuss four zones:
– Generator
– Bus
– Transformer
– Transmission line
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ZONES OF PROTECTION
GENERATOR TRANSFORMER
BUS BUS
TRANSMISSION
LINE
LINE
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GENERATOR PROTECTION
• Faults– Phase or ground faults in the stator or protection zone– Ground faults in the rotor (field windings)
• Abnormal conditions– Loss of or low excitation– Overload– Overvoltage– Low or high frequency– Motoring– Connecting to grid out of synchronism– Loss of synchronism with the grid
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BUS PROTECTION
• Ground faults
• Phase faults
• Overvoltage protection normally not applied
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TRANSFORMER PROTECTION
• Ground and phase faults (87)
• Overvoltage (59)
• Overload or backup protection (51, 21)
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TRANSMISSION LINE PROTECTION
• Ground and phase faults (21, 87, 67n)
• Overvoltage (59)
• Time delayed backup protection ( 2, 21)
• High speed clearing of faults is dependent upon communications between protective relays at the ends of the line: pilot or communications based protection schemes
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TYPES OF PILOT PROTECTION
• Pilot wire (requires a cable)• Directional comparison systems
– DCB - directional comparison blocking– DCUB - directional comparison unblocking– POTT - permissive overreaching transfer trip
(popular)– DUTT - direct underreaching transfer trip
(permissive and non-permissive• Phase comparison• Current differential (87) [increasing in popularity]
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PILOT WIRE RELAYING
21LINE
PILOT WIRE CABLE
F1 F2
TRIP
PCB 2TRIP
PCB 1
• For fault at F2 or for load vs at bus 1 and 2 have opposite polarity
• For fault at F1 vs at bus 1 and 2 has same polarity.
8787
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PILOT WIRE RELAYING (HCB-1)
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NOT PILOT WIRE RELAYING
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DCB - DIRECTIONAL
COMPARISON BLOCKING
21LINE
R
XT
XTELEPROTECTION (PLC)TELEPROTECTION (PLC)
F1 F2
TRIP
PCB 2
TRIP
PCB 1
21
R
21
F
16
MS
21
F
21
R
TX
RXAND
16
MS
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POTT - PERMISSIVE
OVERREACHING TRANSFER TRIP
21LINE
TELEPROTECTIONTELEPROTECTION
F1 F2
TRIP
PCB 2
TRIP
PCB 1
21
21
TX
RXAND
TX
RX
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PROTECTIVE RELAY OPERATION
URL El Dorado 500 Kv Switch.url
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PROTECTION SYSTEM FAILURE
URL Transformer Fire.url