3171456 Power System Protection-I
-
Upload
praveen-paul -
Category
Documents
-
view
260 -
download
11
Transcript of 3171456 Power System Protection-I
![Page 1: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/1.jpg)
© 2005. T.S. Sidhu
Course Instructor :Course Instructor : Prof. Tarlochan Singh Sidhu, Prof. Tarlochan Singh Sidhu, Ph.D., P.Eng., C.Eng.Ph.D., P.Eng., C.Eng.
Power System ProtectionPower System ProtectionECE 456ECE 456
![Page 2: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/2.jpg)
© 2005. T.S. Sidhu
Protection Relay TechnologyProtection Relay Technology
© 2005. T.S. Sidhu
![Page 3: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/3.jpg)
© 2005. T.S. Sidhu
Relay TechnologyRelay Technology
1. Functional block diagram
2. Relay technology evolution
3. Electromechanical relays
4. Solid state relays
5. Numerical relays
6. Impedance relay design using different
technologies
ContentsContents
![Page 4: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/4.jpg)
© 2005. T.S. Sidhu
Relay TechnologyRelay Technology
1. Functional block diagram
2. Relay technology evolution
3. Electromechanical relays
4. Solid state relays
5. Numerical relays
6. Impedance relay design using different
technologies
ContentsContents
![Page 5: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/5.jpg)
© 2005. T.S. Sidhu
Relay TechnologyRelay Technology
Protection Relay Functional Block DiagramProtection Relay Functional Block Diagram
Input and Input and signal signal
conditioningconditioning
Decision Decision MakingMaking
Scheme logic Scheme logic and output and output
IIor/and
VV
Trip Trip and
AlarmAlarm
The voltage and/or current signal is first reduced to measurable quantities
and necessary conditioning done
The decision making stage does the actual protection as per the set value
The output stage implements the necessary logic before issuing trip and
alarm commands.
![Page 6: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/6.jpg)
© 2005. T.S. Sidhu
Relay TechnologyRelay Technology
1. Functional block diagram
2. Relay technology evolution
3. Electromechanical relays
4. Solid state relays
5. Numerical relays
6. Impedance relay design using different
technologies
ContentsContents
![Page 7: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/7.jpg)
© 2005. T.S. Sidhu
PROTECTION RELAY
Relay TechnologyRelay Technology
Protection Relay Technology EvolutionProtection Relay Technology Evolution
![Page 8: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/8.jpg)
© 2005. T.S. Sidhu
PROTECTION RELAY
Electromechanical Static
Relay TechnologyRelay Technology
Protection Relay Technology EvolutionProtection Relay Technology Evolution
Electromechanical Electromechanical : A protection relay design which uses
magnetomotive force in its decision making stage and has
moving parts in it.
Static Static : A protection relay design which does not have any
moving part in the decision making stage
![Page 9: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/9.jpg)
© 2005. T.S. Sidhu
PROTECTION RELAY
Electromechanical Static
Rotational torque
Attractive force
Relay TechnologyRelay Technology
Protection Relay Technology EvolutionProtection Relay Technology Evolution
![Page 10: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/10.jpg)
© 2005. T.S. Sidhu
PROTECTION RELAY
Electromechanical Static
Analog Electronic
Digital Electronic
Processor Based
Rotational torque
Attractive force
Relay TechnologyRelay Technology
Protection Relay Technology EvolutionProtection Relay Technology Evolution
![Page 11: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/11.jpg)
© 2005. T.S. Sidhu
Protection Relay Technology EvolutionProtection Relay Technology Evolution
PROTECTION RELAY
Electromechanical Static
Analog Electronic
Digital Electronic
Processor Based
μPs
DSPs
Rotational torque
Attractive force
Relay TechnologyRelay Technology
![Page 12: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/12.jpg)
© 2005. T.S. Sidhu
PROTECTION RELAY
Electromechanical Static
Analog Electronic
Digital Electronic
Processor Based
μPs
DSPs
hardware
software
Rotational torque
Attractive force
Relay TechnologyRelay Technology
Protection Relay Technology EvolutionProtection Relay Technology Evolution
![Page 13: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/13.jpg)
© 2005. T.S. Sidhu
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
Communication Interface
DATA
BUS
Power Supply
Digital Input(Optos)
Digital Output(Relays)
VTAFiltering & Buffer
VTB
VTC
CTA
CTB
CTC
S/H
Filtering & Buffer
Filtering & Buffer
Filtering & Buffer
Filtering & Buffer
Filtering & Buffer
ADC
S/H
S/H
S/H
S/H
S/H
Crystal Clock
ADC
ADC
ADC
ADC
ADC
DIGITAL
MUX
fromVT
fromCT
Relay TechnologyRelay Technology
Block diagram of a Modern Numerical relayBlock diagram of a Modern Numerical relay
![Page 14: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/14.jpg)
© 2005. T.S. Sidhu
Relay TechnologyRelay Technology
1. Functional block diagram
2. Relay technology evolution
3. Electromechanical relays
4. Solid state relays
5. Numerical relays
6. Impedance relay design using different
technologies
ContentsContents
![Page 15: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/15.jpg)
© 2005. T.S. Sidhu
Electromechanical RelaysElectromechanical Relays
Plunger-type relays
Balanced beam relays
Induction disc relays
Induction cup relays
ConstructionsConstructions
![Page 16: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/16.jpg)
© 2005. T.S. Sidhu
Plunger Type RelaysPlunger Type Relays
A simple over voltage relay is shown
The coil impedance and turns decide the operating torque
The spring provides the restraining force
The relay operating value (setting) is thus controlled by both the coil and spring
![Page 17: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/17.jpg)
© 2005. T.S. Sidhu
Balanced Beam RelaysBalanced Beam Relays
Beam is balanced for normal conditions
During fault, the operating torque exceeds the restraining torque causing
the beam to tilt and close the contacts
![Page 18: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/18.jpg)
© 2005. T.S. Sidhu
Induction Disc RelaysInduction Disc Relays
Flux produced by both voltage and current coils. The interaction of these two
fluxes produces a rotational torque (like induction motors)
Disc rotates and closes contact during fault
![Page 19: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/19.jpg)
© 2005. T.S. Sidhu
Induction Cup RelaysInduction Cup Relays
+
V-IZr2
+
φo
φ p
IZr1-V
Similar to disc, but the freedom of rotation is restricted.
Cannot provide additional time delay in operation..
![Page 20: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/20.jpg)
© 2005. T.S. Sidhu
Relay TechnologyRelay Technology
1. Functional block diagram
2. Relay technology evolution
3. Electromechanical relays
4. Solid state relays
5. Numerical relays
6. Impedance relay design using different
technologies
ContentsContents
![Page 21: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/21.jpg)
© 2005. T.S. Sidhu
Solid State Technology (Static)Solid State Technology (Static)
Common Solid State Circuits employed in Relays
Squaring circuits
Phase shifting circuits
Integrators
Coincidence circuits
Level Detection
‘AND’ing circuits
The above circuits are realised using transistors, Op-Amps, ICs etc.
A combination of the above circuits are used to implement a particular
protection in static technology
![Page 22: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/22.jpg)
© 2005. T.S. Sidhu
Solid State Technology Solid State Technology
Squaring circuitsSquaring circuits
![Page 23: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/23.jpg)
© 2005. T.S. Sidhu
Solid State Technology Solid State Technology
Phase Shifting circuitPhase Shifting circuit
![Page 24: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/24.jpg)
© 2005. T.S. Sidhu
Solid State Technology Solid State Technology
IntegratorsIntegrators
![Page 25: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/25.jpg)
© 2005. T.S. Sidhu
Solid State Technology Solid State Technology
Coincidence circuitsCoincidence circuits
![Page 26: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/26.jpg)
© 2005. T.S. Sidhu
Solid State Technology Solid State Technology
Level DetectorsLevel Detectors
![Page 27: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/27.jpg)
© 2005. T.S. Sidhu
Relay TechnologyRelay Technology
1. Functional block diagram
2. Relay technology evolution
3. Electromechanical relays
4. Solid state relays
5. Numerical relays
6. Impedance relay design using different
technologies
ContentsContents
![Page 28: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/28.jpg)
© 2005. T.S. Sidhu
Numerical Relay Numerical Relay -- Data FlowData Flow
…..01470598096903780009
CTs & VTsPOWER SYSTEM
ADC
PROCESSOR
![Page 29: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/29.jpg)
© 2005. T.S. Sidhu
Phasor Estimation Phasor Estimation -- ExampleExample
PROCESSOR0009
Inputs (3-Window Algorithm)
Current : 0009
Previous : -0500, -1230
Processing
1. Calculate Phasors
2. Apply logics (Algorithms)
3. Give Trip SignalTrip / No-Trip
Note:
All these processing should be done within T seconds (1 sampling interval), before the next sample arrives
ADC
![Page 30: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/30.jpg)
© 2005. T.S. Sidhu
Data Flow Data Flow –– After T secondsAfter T seconds
PROCESSOR
0378Inputs (3-Window Algorithm)
Current : 0378
Previous : 0009, -0500
Processing
1. Calculate Phasors
2. Apply logics (Algorithms)
3. Give Trip SignalTrip / No-Trip
Note:
All these processing should be done within T seconds (1 sampling interval), before the next sample arrives
ADC
![Page 31: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/31.jpg)
© 2005. T.S. Sidhu
Data Flow Data Flow –– After 2T secondsAfter 2T seconds
PROCESSOR
0969Inputs (3-Window Algorithm)
Current : 0969
Previous : 0378, 0009
Processing
1. Calculate Phasors
2. Apply logics (Algorithms)
3. Give Trip SignalTrip / No-Trip
Note:
All these processing should be done within T seconds (1 sampling interval), before the next sample arrives
ADC
![Page 32: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/32.jpg)
© 2005. T.S. Sidhu
Data Flow Data Flow –– After 3T secondsAfter 3T seconds
PROCESSOR
0598Inputs (3-Window Algorithm)
Current : 0598
Previous : 0969, 0378
Processing
1. Calculate Phasors
2. Apply logics (Algorithms)
3. Give Trip SignalTrip / No-Trip
Note:
All these processing should be done within T seconds (1 sampling interval), before the next sample arrives
ADC
![Page 33: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/33.jpg)
© 2005. T.S. Sidhu
Relay TechnologyRelay Technology
1. Functional block diagram
2. Relay technology evolution
3. Electromechanical relays
4. Solid state relays
5. Numerical relays
6. Impedance relay design using different
technologies
ContentsContents
![Page 34: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/34.jpg)
© 2005. T.S. Sidhu
Implementation of a single phase impedance relay in different relay
technologies
Electrometrical
Static Analgue
Numerical
Input signals
Voltage
Current
Setting
Impedance setting
Relay TechnologyRelay Technology
![Page 35: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/35.jpg)
© 2005. T.S. Sidhu
Impedance Relay CharacteristicsImpedance Relay Characteristics
Impedance relay - circular characteristic with center at the origin
r1
r1 |Z||Z|zz ≤≤
oo 9090 +<<− ψ
Operate
Restrain
δ
Zr1
Zr2
Re
Im
C
Z
Operate
Restrain
Zr1
Zr2
Re
Im
C
Z
ψ
Zr1=Zr2 = Reach settingZ = Vf/If = Measured impedance (fault voltage/fault current)
![Page 36: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/36.jpg)
© 2005. T.S. Sidhu
Impedance Relay Impedance Relay –– Electromechanical Electromechanical
The characteristic can be defined by
Multiplying both sides by I, we get
|Z||Z| r1≤
|IZ||IZ| r1≤
IZr1V
IZ is equal to V, the voltage at the relay location if Z is the impedance from the relay location to the fault
This can be implemented by comparing flux
|IZ||V| r1≤
Balanced Beam constructionBalanced Beam construction
Operate
Restrain
δ
Zr1
Zr2
Re
Im
C
Z
![Page 37: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/37.jpg)
© 2005. T.S. Sidhu
Impedance Relay Impedance Relay –– Electromechanical Electromechanical
The characteristic can also defined by-90o < ψ < +90’o
where ψ is the angle between Z-Zr2and Zr1-ZMultiplying both terms by I, we get
IZ-IZr2 and IZr1-IZ.
+
V-IZr2
+
φo
φ p
IZr1-V
Induction Cup constructionInduction Cup constructionNow substituting IZ by V, we get
V-IZr2 and IZr1-V.The characteristic can now be defined by(V-IZr2)(IZr1-V) cos (ψ)>0
Operate
Restrain
Zr1
Zr2
Re
Im
C
Z
ψ
![Page 38: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/38.jpg)
© 2005. T.S. Sidhu
Impedance Relay Impedance Relay –– Solid StateSolid State
The characteristic of an impedance relay is defined by
||||0 VIZr1 −≤
|IZ||V| r1≤
Impedance magnitude comparatorImpedance magnitude comparator
*Z r1 *(-1)
ADD
Level Detector>
I V
Trip
Convert to dcvoltage
Convert to dcvoltage
0
Operate
Restrain
δ
Zr1
Zr2
Re
Im
C
Z
![Page 39: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/39.jpg)
© 2005. T.S. Sidhu
Impedance Relay Impedance Relay –– Solid StateSolid State
When ψ is greater than -90o and is less than +90o (the impedance is inside the characteristics), the coincidence between the positive parts of the waveforms is for more than one quarter of the period.
The coincidence logic, therefore, provides a means of providing a phase comparator.
Squaring circuit
V-IZr2
Squaring circuit
Coincidence
90o
Trip
Integrator
Level detector
IZr1-V
Impedance Phase comparatorImpedance Phase comparator
Operate
Restrain
Zr1
Zr2
Re
Im
C
Z
ψ
![Page 40: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/40.jpg)
© 2005. T.S. Sidhu
Phase displacement ψ can also be checked using zero crossing detection technique.
Squaring circuit Phase shifting &Pulse circuits
AND
Trigger circuit
V-IZr2 IZr1-V
Trip
Squaring circuit
V-IZr2
Trip
IntegratedIZr1-V
Level detector
IZr1-V
Zero Crossing detector
Output of AND gate
Impedance Relay Impedance Relay –– Solid StateSolid State
![Page 41: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/41.jpg)
© 2005. T.S. Sidhu
Single Phase Impedance relaySingle Phase Impedance relay
Impedance Relay Impedance Relay –– NumericalNumerical
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
Communication Interface
DATA
BUS
Power Supply
Digital Input(Optos)
Digital Output(Relays)
VT Filtering & Buffer
CT
S/H
Filtering & Buffer
ADC
S/H
Crystal Clock
ADC
DIGITAL
MUX
fromVT
fromCT
To CB
FromPlant
![Page 42: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/42.jpg)
© 2005. T.S. Sidhu
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
Communication Interface
DATA
BUS
Power Supply
Digital Input(Optos)
Digital Output(Relays)
Filtering & Buffer S/H
Filtering & Buffer
ADC
S/H
Crystal Clock
ADC
DIGITAl
MUX
To CB
FromPlant
Input VT & CTInput VT & CT
Impedance Relay Impedance Relay –– NumericalNumerical
VT
CT
fromVT
fromCT
The input current and voltage is reduced to electronics measurable range. Typical 1 to 5V full scale.
![Page 43: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/43.jpg)
© 2005. T.S. Sidhu
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
Communication Interface
DATA
BUS
Power Supply
Digital Input(Optos)
Digital Output(Relays)
S/H ADC
S/H
Crystal Clock
ADC
DIGITAl
MUX
To CB
FromPlant
VT
CT
fromVT
fromCT
Filtering & Buffer
Filtering & Buffer
Filtering & BufferingFiltering & Buffering
Impedance Relay Impedance Relay –– NumericalNumerical
Analogue signal conditioning, to make is suitable for digitizing.
![Page 44: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/44.jpg)
© 2005. T.S. Sidhu
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
Communication Interface
DATA
BUS
Power Supply
Digital Input(Optos)
Digital Output(Relays)
ADC
Crystal Clock
ADC
DIGITAl
MUX
To CB
FromPlant
VT
CT
fromVT
fromCT
Filtering & Buffer
Filtering & Buffer
S/H
S/H
Sample & holdSample & hold
Impedance Relay Impedance Relay –– NumericalNumerical
Sampling - Converting the continuous time analog signal to discrete time analog signal
Holds the signal at the sampled value for digitizing
![Page 45: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/45.jpg)
© 2005. T.S. Sidhu
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
Communication Interface
DATA
BUS
Power Supply
Digital Input(Optos)
Digital Output(Relays)
Crystal Clock
DIGITAl
MUX
To CB
FromPlant
VT
CT
fromVT
fromCT
Filtering & Buffer
Filtering & Buffer
S/H
S/H
ADC
ADC
Analog to Digital ConverterAnalog to Digital Converter
Impedance Relay Impedance Relay –– NumericalNumerical
Converts the instantaneous current and voltage to equivalent digital value (0s and 1s)
No. of bits representing each value depends on resolution of ADC
![Page 46: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/46.jpg)
© 2005. T.S. Sidhu
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
Communication Interface
DATA
BUS
Power Supply
Digital Input(Optos)
Digital Output(Relays)
Crystal Clock
To CB
FromPlant
VT
CT
fromVT
fromCT
Filtering & Buffer
Filtering & Buffer
S/H
S/H
ADC
ADC
DIGITAL
MUX
MultiplexerMultiplexer
Impedance Relay Impedance Relay –– NumericalNumerical
Sends digitized current and voltage in turns to the data bus.
Controlled from DSP
![Page 47: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/47.jpg)
© 2005. T.S. Sidhu
Communication Interface
DATA
BUS
Power Supply
Digital Input(Optos)
Digital Output(Relays)
Crystal Clock
To CB
FromPlant
VT
CT
fromVT
fromCT
Filtering & Buffer
Filtering & Buffer
S/H
S/H
ADC
ADC
DIGITAl
MUX
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
DSPDSP
Implements distance protection (magnitude, phase comparison, etc) – more in next lectureFind phasor from digital samples
Calculate Impedance
Compare with setting
Impedance Relay Impedance Relay –– NumericalNumerical
![Page 48: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/48.jpg)
© 2005. T.S. Sidhu
DATA
BUS
Power Supply
Crystal Clock
VT
CT
fromVT
fromCT
Filtering & Buffer
Filtering & Buffer
S/H
S/H
ADC
ADC
DIGITAl
MUX
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
Communication Interface
Digital Input(Optos)
Digital Output(Relays)To CB
FromPlant
Digital I/O and Digital I/O and CommunicatonCommunicaton
Digital I/O to issue trip/alarm commands and receive plant status
Communication for local and remote communication / SCADA, DCS
Impedance Relay Impedance Relay –– NumericalNumerical
![Page 49: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/49.jpg)
© 2005. T.S. Sidhu
DATA
BUS
VT
CT
fromVT
fromCT
Filtering & Buffer
Filtering & Buffer
S/H
S/H
ADC
ADC
DIGITAl
MUX
Digital Signal Processor & User Interface
• Data acquisition• Digital Filtering• Protection Algorithm • Scheme logic• DR, ER, FR, etc.• Comm. & HMI
Communication Interface
Digital Input(Optos)
Digital Output(Relays)To CB
FromPlant
Power Supply
Crystal Clock
Power Supply & ClockPower Supply & Clock
Impedance Relay Impedance Relay –– NumericalNumerical
DC/AC to DC converter to provide power to circuit comments at different rail voltage
Crystal to provide reference clock for digital processing
![Page 50: 3171456 Power System Protection-I](https://reader034.fdocuments.us/reader034/viewer/2022050710/5500a1744a7959995f8b4b8c/html5/thumbnails/50.jpg)
© 2005. T.S. Sidhu
Any protection can be implemented in all technology
Though technology has evolved from electromechanical to
numerical, each has its own strength
However the flexibility and series of extra features offered by
numerical relays combined with advancements in DSP and
communication has made numerical relays very popular in recent
times
Relay TechnologyRelay Technology