The document provides an overview of protective relaying. It discusses the knowledge required for protective relaying including equipment behavior, faults, protection philosophies and terminology. It describes power system components that require protection like generators, transformers, transmission lines etc. The objectives, philosophy and requirements of protection schemes are explained. The document discusses zones of protection, primary and backup protection. It also covers protective relay inputs, outputs, settings, and characteristics. The evolution of relay technology from electromechanical to solid state to numerical relays using microprocessors is summarized.
Lec 1_Introduction to Power System
Protection.pdfAhmedHElashry
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
line
Lec 1_Introduction to Power System
Protection.pdfAhmedHElashry
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
line
Unit I: Introduction to Protection System:
Introduction to protection system and its elements, functions of protective relaying, protective zones, primary and backup protection, desirable qualities of protective relaying, basic terminology.
Relays:
Electromagnetic, attracted and induction type relays, thermal relay, gas actuated relay, design considerations of electromagnetic relay.
Unit-II: Relay Application and Characteristics:
Amplitude and phase comparators, over current relays, directional relays, distance relays, differential relay.
Static Relays: Comparison with electromagnetic relay, classification and their description, over current relays, directional relay, distance relays, differential relay.
Unit-III Protection of Transmission Line:
Over current protection, distance protection, pilot wire protection, carrier current protection, protection of bus, auto re-closing,
Unit-IV: Circuit Breaking:
Properties of arc, arc extinction theories, re-striking voltage transient, current chopping, resistance switching, capacitive current interruption, short line interruption, circuit breaker ratings.
Testing Of Circuit Breaker: Classification, testing station and equipments, testing procedure, direct and indirect testing.
Unit-V Apparatus Protection:
Protection of Transformer, generator and motor.
Circuit Breaker: Operating modes, selection of circuit breakers, constructional features and operation of Bulk Oil, Minimum Oil, Air Blast, SF6, Vacuum and d. c. circuit breakers.
To sense/detect the fault occurrence and other abnormal conditions at the protected equipment/area/section.
To operate the correct circuit breakers so as to disconnect only the faulty equipment/area/section as quickly as possible, thus minimizing the damage caused by the faults.
To operate the correct circuit breakers to isolate the faulty equipment/area/section from the healthy system in the case of abnormalities like overloads, unbalance, undervoltage, etc.
To clear the fault before the system becomes unstable.
To identify distinctly where the fault has occurred.
Need for protection
Nature and causes of faults
Types of faults
Fault current calculation using symmetrical components
Zones of protection
Primary and back up protection
Essential qualities of protection
Typical protection schemes.
FUNDAMENTALS OF POWER SYSTEM PROTECTION
FUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTION
Unit I: Introduction to Protection System:
Introduction to protection system and its elements, functions of protective relaying, protective zones, primary and backup protection, desirable qualities of protective relaying, basic terminology.
Relays:
Electromagnetic, attracted and induction type relays, thermal relay, gas actuated relay, design considerations of electromagnetic relay.
Unit-II: Relay Application and Characteristics:
Amplitude and phase comparators, over current relays, directional relays, distance relays, differential relay.
Static Relays: Comparison with electromagnetic relay, classification and their description, over current relays, directional relay, distance relays, differential relay.
Unit-III Protection of Transmission Line:
Over current protection, distance protection, pilot wire protection, carrier current protection, protection of bus, auto re-closing,
Unit-IV: Circuit Breaking:
Properties of arc, arc extinction theories, re-striking voltage transient, current chopping, resistance switching, capacitive current interruption, short line interruption, circuit breaker ratings.
Testing Of Circuit Breaker: Classification, testing station and equipments, testing procedure, direct and indirect testing.
Unit-V Apparatus Protection:
Protection of Transformer, generator and motor.
Circuit Breaker: Operating modes, selection of circuit breakers, constructional features and operation of Bulk Oil, Minimum Oil, Air Blast, SF6, Vacuum and d. c. circuit breakers.
To sense/detect the fault occurrence and other abnormal conditions at the protected equipment/area/section.
To operate the correct circuit breakers so as to disconnect only the faulty equipment/area/section as quickly as possible, thus minimizing the damage caused by the faults.
To operate the correct circuit breakers to isolate the faulty equipment/area/section from the healthy system in the case of abnormalities like overloads, unbalance, undervoltage, etc.
To clear the fault before the system becomes unstable.
To identify distinctly where the fault has occurred.
Need for protection
Nature and causes of faults
Types of faults
Fault current calculation using symmetrical components
Zones of protection
Primary and back up protection
Essential qualities of protection
Typical protection schemes.
FUNDAMENTALS OF POWER SYSTEM PROTECTION
FUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTIONFUNDAMENTALS OF POWER SYSTEM PROTECTION
An A.C. device used to change high voltage low current A.C. into low voltage high current A.C. and vice-versa without changing the frequency
In brief,
1. Transfers electric power from one circuit to another
2. It does so without a change of frequency
3. It accomplishes this by electromagnetic induction
4. Where the two electric circuits are in mutual inductive influence of each other.
6th International Conference on Machine Learning & Applications (CMLA 2024)ClaraZara1
6th International Conference on Machine Learning & Applications (CMLA 2024) will provide an excellent international forum for sharing knowledge and results in theory, methodology and applications of on Machine Learning & Applications.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.
KuberTENes Birthday Bash Guadalajara - K8sGPT first impressionsVictor Morales
K8sGPT is a tool that analyzes and diagnoses Kubernetes clusters. This presentation was used to share the requirements and dependencies to deploy K8sGPT in a local environment.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
We have compiled the most important slides from each speaker's presentation. This year’s compilation, available for free, captures the key insights and contributions shared during the DfMAy 2024 conference.
HEAP SORT ILLUSTRATED WITH HEAPIFY, BUILD HEAP FOR DYNAMIC ARRAYS.
Heap sort is a comparison-based sorting technique based on Binary Heap data structure. It is similar to the selection sort where we first find the minimum element and place the minimum element at the beginning. Repeat the same process for the remaining elements.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
2. Protective Relaying - Introduction
Requires knowledge of :
Equipments to be protected
Behavior of equipment
Faults in an equipment
Protection philosophies
Terminologies used
3. Protective Relaying - Introduction
Requires knowledge of :
IEEE notations
Protection schemes
Single line diagram
Symmetrical components
Electronics
Communication methods
4. Power System - Objective
• To generate and supply electrical energy to
the consumers - reliably and economically
• Better reliability can be achieved by
improved system design, allowing for
sufficient spare capacity, considering future
additions and/or expansions
5. Power Systems Protection -Introduction
Power System Components
1. Generators
2. Transformers
3. Transmission Lines
4. Feeders
5. Motors
6. Capacitor Banks
7. Bus Bars
9. Objectives of protection
Prevent deterioration by disconnecting
circuits & equipments subjected to :
• Overload
• Over-temperature
• Under-over voltages
• Unbalanced currents
• Under – over frequency
10. Objectives of protection
• Loss of field
• Loss of synchronization
• Anti-motoring
• Reverse power
• Reverse current
• Phase reversal &
• Open phase
11. Objectives of protection
Limit damage by disconnecting circuits
& equipments subjected to :
• Short circuits
• Earth faults
12. Power Systems Protection -Introduction
Protection – Purpose
• To detect abnormalities (faults)
• To eliminate such abnormality
- by isolating the smallest portion of the system
in the shortest period of time
• To prevent injury to personnel
• To prevent damage to equipment
13. Power Systems Protection -Introduction
Protective Relay – What should it do ?
• Monitor system parameters continuously
(V, I, P, F)
• Operate quickly when necessary
(Dependability)
• Should not operate wrongly
(stability, discrimination)
14. Protective Relaying
Design of Protective Schemes
• General Philosophy
• Reliability (Dependability and Security)
• Sensitivity
• Speed of operation
• Economics
• Simplicity
16. The 4 ‘S’ of a Protection Scheme
• Selectivity: When a fault occurs, the
protection system is required to select and
trip only the nearest circuit breakers. This
property of selective tripping is also called
discrimination. This can either be a current
based discrimination or a time based
discrimination or a combination of both.
17. The 4 ‘S’ of a Protection Scheme
• Stability: This is the ability of the protection
system to remain inert to all load conditions
and faults external to the relevant zone of
the protection scheme. This is of particular
importance in Unit Protection Schemes
(e.g.) Differential Protection, REF
Protection, etc.
18. The 4 ‘S’ of a Protection Scheme
• Speed: The primary function of a
protection scheme is to detect and isolate
faults from a power system in a very short
time than which could be achieved
manually. This is to safeguard continuity of
supply to healthier portions, by removing
each disturbance , before it leads to wide
spread loss and/or plant shut downs.
19. The 4 ‘S’ of a Protection Scheme
• Sensitivity: This refers to the minimum
operating quantity requirements of a
complete protection system. A protection
system is said to be sensitive, if the
operating quantity is low. But, with respect
to individual relays, it is not the current or
voltage, but the VA consumption of the
relay at the minimum operating quantity.
20. Device Function Numbers (ANSI/IEEE Codes)
The devices in the switching equipment are denoted
by numbers, with appropriate suffix letters when
necessary, according to the functions they perform.
These numbers are based on a system adopted as
standard for automatic switchgear by IEEE and are
incorporated in American Standard (ANSI) C37.2-
1970.
This system is used in connection diagrams, in
instruction booklets and in specifications to designate
the relays and other devices to save text and space.
Power Systems Protection -Introduction
21. Protection – ANSI Codes
Code numbers
Used to denote
Protections
On a SLD
Power Systems Protection -Introduction
22. Zone of protection
The zone of protection of relay or
circuit breaker trip device is that
segment of the power system in
which the occurrence of assigned
abnormal conditions should cause the
protective device to operate
31. Protection
Primary Protection
First line of defence
Is responsible to protect the power system
elements from all types of faults
(e.g.- High speed differential relay,Instantaneous overcurrent relay)
Back-up Protection
Operates only if primary protection fails
(e.g.phase time overcurrent relay)
32. Power Systems Protection -Introduction
Protective Relay Scheme – What is it ?
• A protective relay
• CT / PT
• Auxiliary Power supply (24 V to 240 V AC/ DC)
• Switching device ( Breaker/ Contactor)
• Trip Coil
• Alarm / Trip contact
• Control Wiring
34. Inputs to Protective relays
OVER CURRENT RELAYS CURRENT
UNDER / OVER VOLTAGE RELAYS VOLTAGE
SYNCHRONISING RELAYS
FREQUENCY RELAYS
DISTANCE RELAYS CURRENT &
DIRECTIONAL RELAYS VOLTAGE
REVERSE POWER RELAYS POWER
SUDDEN PRESSURE RELAY PRESSURE
OVER TEMPERATURE RELAY TEMPERATURE
36. Comparing element or
Comparator
Comparison is made on the basis of
amplitude, relative phase or
combination of amplitude & relative
phase.
• Single input – Electromagnetic
• Multi input – Static
• Output – Mechanical torque /
Electrical signal
37. Control element
Operated in one direction or other by
the output of comparator and it
controls tripping of circuit breaker.
39. Protective relays - Terminology
SETTINGS
PICK UP
LOW SET
HIGH SET
TMS
STEPS
TIME DELAYS
INSTANTANEOUS
INVERSE TIME
DEFINITE TIME
RATINGS
CT
PT
AUX. POWER
BURDEN
CT INPUT
PT INPUT
DIRECT SEQUENCE
NEGATIVE SEQUENCE
ZERO SEQUENCE
VECTORS
CURRENT
VOLTAGE
IMPEDANCE
MACHINE RELATED
PERCENT. IMPEDANCE
FULL LOAD RATING
TIME CONSTANT
OVER LOAD CHAR.
SYSTEM
GROUNDED
UNGROUNDED
RESISTANCE GROUNDED
OPERATIONAL
MASTER TRIP
LOCK OUT
RESTRAINTS
INTER TRIP
BLOCKING
FLAG
SELF RESET
HAND RESET
MANUAL RESET
RELAY TEST
ANALYSIS
TRIP DATA
W/F CAPTURE
DIAGNOSTICS
CONNECTIONS
RESIDUAL
OPEN DELTA
CBCT
40. Power System - Faults
Current
Over Load
Over Current
Earth Fault
Current Unbalance
Dir. Over Current
Dir. Earth Fault
Voltage
Over Voltage
Under Voltage
Voltage Unbalance
Neutral shift
Frequency
Over Frequency
Under Frequency
dF/dT
Power
Active power
Reactive power
Over power
Under power
Reverse power
Computed
Over fluxing
Loss of field
Differential O/C
Restricted E/F
Under Impedance
Control/Management
Synchronizing
Islanding
Load shedding
Power Systems Protection -Introduction
41. Power System – Fault Handling
Trip & Isolate
Breaker is tripped on fault
Faulty section is isolated
Control & Regulate
Breaker is not tripped
Corrective actions
Generated on line
Power Systems Protection -Introduction
42. Power Systems Protection -Introduction
Relay operation when a fault occurs
• Each relay should protect a
specific zone in the system
• If fault is inside its zone,
relay should operate and isolate the zone
• If fault is outside zone,
Relay should not operate –
Some other relay should operate and isolate
43. Power Systems Protection -Introduction
What happens when a fault occurs
• Fault current flows through number of relays
• Some of these relays will start to operate
• Only one relay should trip and
interrupt fault current
• Remaining relays will reset after above
44. Protection Relays – Inputs / Out puts
Inputs
Current CTs
Voltage PTs
Frequency PTs
Power CTs + PTs
Outputs
Trip Contact
Power Systems Protection -Introduction
45. Protection Relays – Settings
Pick up setting Low set
Highset
Time delay setting Definite time
Inverse time
% of CT
Rating
TMS
Setting
Power Systems Protection -Introduction
46. Power System – Trip time characteristics
I/Is
t
10
1.3 or
3.0 sec
1.4
LS
Power Systems Protection -Introduction
47. Power System – Trip time characteristics
I/Is
t
10
1.3 or
3.0 sec
50 msec
6
HS
1.4
LS
Power Systems Protection -Introduction
48. TMS=1
I/Is=2 I/Is=4 I/Is=6 Is=8 I/Is=10 I/Is=15 I/Is=20
Normal Inv 3 sec 10.13 5.03 3.87 3.33 3 2.54 2.29
Normal Inv 1.3 sec 4.39 2.18 1.68 1.44 1.3 1.1 .99
Very Inverse 13.5 4.5 2.7 1.93 1.5 .96 .71
Extremely Inverse 26.66 5.33 2.28 1.27 0.81 0.36 0.20
Typical Inverse time delays
Power Systems Protection -Introduction
49. [ A]
t(I) = ---------------- * TMS
[(I/Is)a – 1]
Where,
t(I) = Trip Time in Seconds
I = Fault Current
Is = Set Current
TMS = Time Multiplier Setting
Power System – Trip time characteristics
Inverse time delays – General Algorithm
As per BS 142 & IEC 60255-4
Power Systems Protection -Introduction
50. Curve Name A a
Normal Inverse 1.3 Sec. 0.0613 0.02
Normal Inverse 3.0 Sec. 0.1414 0.02
Very Inverse 13.5 1
Extremely Inverse 80 2
Power System – Trip time characteristics
Inverse time delays – General Algorithm
Power Systems Protection -Introduction
51. User’s Expectations
Sense a fault &
Initiate trip contact CONVENTIONAL
Parameter display
Event record
Fault data record
Wave form record
Communication
Control logic
PRESENT DAY
NEEDS
52. Basic types of Relays
• Magnitude relay
• Directional relay
• Ratio relay
• Differential relay
• Pilot relay
56. Electromechanical relays
ADVANTAGES LIMITATIONS
WELL PROVEN(?) LARGE SIZE
LOW COST INACCURACY
SELF POWERED HIGH BURDEN
LARGE VARIETY
LIMITED PROTECTIONS
DIFFICULT TO CO-ORDINATE
NEED FOR EXTRA HARDWARE
INTROVERT IN NATURE
58. Solid state relays
ADVANTAGES LIMITATIONS
SMALL SIZE NO COST ADVANTAGE
LOW BURDEN HIGHLY NOISE PRONE
EASY TO MANUF DRIFT IN SETTINGS
INACCURACY
LARGE VARIETY
LIMITED PROTECTIONS
DIFFICULT TO CO-ORDINATE
NEED FOR EXTRA HARDWARE
LOW RELIABILITY
INTROVERT IN NATURE
59. Increase in system capacities
New problems to be handled
New utility conditions
Low factor of safety on equipments
Trip information / analysis
Co-ordination problems
Self diagnostic feature
Concept of “UNMANNED S/S”
Need for new technology
61. MICROPROCESSOR BASED RELAYS - BACKGROUND WORK
1960s
A FEW CONCEPTS WERE PROPOSED
HARDWARE WAS VERY EXPENSIVE
BENEFITS OF MICROPROCESSORS FOR
RELAYS WERE NOT CLEAR
IEEE ARTICLE “FAULT PROTECTION WITH A
DIGITAL COMPUTER” OUTLINED THE FEASIBILITY &
PROBLEMS ASSOCIATED IN S/S PROTECTION WHEN A
DIGITAL COMPUTER IS USED
62. MICROPROCESSOR BASED RELAYS - BACKGROUND WORK
1970s
TWO PAPERS WERE PUBLISHED
“DIGITAL CALCULATION OF IMPEDANCE FOR TRANSMISSION LINE PROTECTION”
“ 3 PH TRANSMISSION LINE PROTECTION WITH A DIGITAL COMPUTER”
PROMINENT MANUFACTURERS LIKE WESTINGHOUSE, IBM
STARTED INVESTIGATING S/S COMPUTER SYSTEMS
PHILADELPHIA ELECTRIC & GE INITIATED PROJECTS ON
DIGITAL TECHNIQUES FOR PROTECTION
VARIOUS ALGORITHMS WERE DERIVED FOR
DIGITAL CALCULATION OF PROTECTION PARAMETRS
EXPERIMENTAL SYSTEMS WERE BUILT BY GE & WESTINGHOUSE
TO CHECK ALGORITHMS
FIRST GENERATION OF MICROPROCESSOR BASED RELAYS BUILT
63. MICROPROCESSOR BASED RELAYS - BACKGROUND WORK
1980s
MAJOR MANUFACTURERS LIKE GE, ABB, GEC , TOSHIBA,
SIEMENS START DESIGN & SALES OF BROAD RANGE OF
PRODUCTS FOR POWER SYSTEM PROTECTION
MICROPROCESSOR IMPROVES PERFORMANCE SPECS
FOR OPERATION IN INDUSTRIAL ENVIRONMENT
MANY PLC BASED SYSTEMS ARE COMMISSIONED IN INDIA BY
L&T, SIEMENS, ECIL ETC.
MANY ELECTRICITY BOARDS & PROCESS PLANTS IN INDIA
START USING MICROPROCESSOR BASED INSTRUMENTS
THE WORD SCADA GETS POPULAR IN INDIA
P[GCIL GOES IN FOR MICROPROCESSOR BASED
DISTANCE RELAYS IN INDIA
64. MICROPROCESSOR BASED RELAYS - BACKGROUND WORK
1990s
ABB & GEC ALSTOM INTRODUCE RANGE OF
MICROPROCESSOR BASED RELAYS FOR
ALLALL UNIT PROTECTIONS
MAJOR MANUFACTURERS LIKE GE, ABB, GEC , TOSHIBA
START DESIGN & SALES OF BROAD RANGE OF PRODUCTS
FOR POWER SYSTEM PROTECTION
MANY ELECTRICITY BOARDS & PROCESS PLANTS IN INDIA
START USING MICROPROCESSOR BASED INSTRUMENTS
PGCIL GOES IN FOR MICROPROCESSOR BASED
DISTANCE RELAYS IN INDIA
MICROCONTROLLERS / DSPs ARE INTRODUCED IN LATE 90s BY
HARDWARE MANUFACTURERS WHICH HAVE IMPROVED THE
SPEED OF OPERATION.
65. MICROPROCESSOR BASED RELAYS - BACKGROUND WORK
1995
L&T COMES OUT WITH RANGE OF
MICROPROCESSOR BASED RELAYS
IN ASSOCIATION WITH
MICROELETTRICA SCIENTIFICA OF ITALY
ABB COINS THE WORD “NUMERIC RELAYS”
FOR ALL RELAYS WITH MICRO CONTROLLER
66. Micro-processor based relays
Offer best solution for present day relaying
due to following:
• Intelligent devices
• Can implement complex algorithms
• Oscillographic information
• Networking
• Multi – functions
• Self diagnostics
• User friendly
67. Numeric relays
- It is an improvement over relays with
Microprocessor
- Heart of the system is a micro-
controller
- Entire operation is based on handling
a set of 8 - bit numbers
68. Protective relays – Comparison
ELECTRO SOLID-STATE NUMERICAL
MECHANICAL
INPUT PEAK S/H CIRCUITS
SENSING COIL DETECTOR A/D CONVERTERS
SETTINGS TAPS ANALOG REF DIGTAL NUMBER
COMPARISON TORQUE ANALOG DIGITAL NUMBER
VOLTAGE
ALGORITHM/ RLC GAIN ADJ. ARITHMATIC
PARAMETER SCALAR SCALAR VECTORIAL
IDENTITY
OUT PUT PHYSICAL DRIVERS LOGIC ARRAY
69. PARAMETER NUMERIC CONVENTIONAL
ACCURACY 1% 5% / 7.5%
BURDEN < 0.5 VA > 5 VA
SETTING RANGES WIDE LIMITED
MULTI FUNCTIONALITY YES NO
SIZE SMALL LARGE
FIELD PROGRAMMABILITY YES NO
PARAMETER DISPLAY YES NO
SYSTEM FLEXILBILITY YES NO
CO-ORDINATION TOOLS MANY TWO
COMMUNICATION YES NO
REMOTE CONTROL YES NO
SPECIALALGORITHMS MANY LIMITED
SPECIAL PROTECTIONS YES NO
SELF DIAGNOSTICS YES NO
ADVANTAGES OF NUMERIC RELAYS
70. Numeric relays
ADVANTAGES OVER
ELECTROMECHANICAL RELAYS
1. FIELD PROGRAMMABILITY
2. PARAMETER DISPLAY
3. SYSTEM FLEXIBILITY
4. CO-ORDINATION
5. COMMUNICATION
6. REMOTE CONTROL
7. SPECIAL ALGORITHMS
8. SUPERIOR PROTECTION
74. FUNCTIONAL BLOCKS OF A NUMERIC RELAY
ANALOG
INPUT
SUB-SYSTEM
DIGITAL
INPUT
SUB-SYSTEM
POWER SUPPLY
MICRO
PROCESSOR
COMMUNICATION
INTERFACE
RAM
ROM
EPROM
FLASH
DIGITAL
OUTPUT
SUB-SYSTEM
D
S
P
75. ANALOG INPUT SUB SYSTEM
CT
PT
SURGE
SUPPRESSION
SURGE
SUPPRESSION
ANALOG
FILTER
ANALOG
FILTER
MUX A / D
CONVERTER
MICRO
PROCESSOR
76. DIGITAL SIGNAL PROCESSORS
Designed for repetitive measurements
Digital filtering
Highly suitable where microprocessor has to do
measurements, logic, communication and other functions
Designed to handle one instructions per clock cycle
(microprocessors need many clocks per instruction)
Improves speed of operation
DSP Types :
- Analog Devices 21XX family
- Texas Instruments TMS3XX family
- Motorola 56XXX family
77. MICROPROCESSORS Vs MICRO CONTROLERS
C
O
N
T
R
O
L
C
O
N
T
R
O
L
Accumulator
Arithmatic Logic
Unit
Data Register
Address Register
Data Register
Arithmetic Logic
Unit
Address Register
Accumulator
I/O
ROM
RAM
EPROM
Timers
Counters
UART
Microprocessor Micro controller
78. TYPES OF MEMORY NUMERIC RELAYS
RAM Read / Write Memory. Used for temporary storage
of variables - like sampled data / oscillographic data
EEPROM / Electrically Erasable Programmable Read Only Memory
NOVRAM Non Volatile RAM
Used for storage of data that remains when power off
(CT/PT/machine ratings, trip settings etc.)
ROM Read Only Memory. Masked version used for high volume
production units. Used for storage of specific programmes.
EPROM Electrically Programmable ROM . Used as above.
Easy to programme and reprogram. Adaptable to changes.
FLASH New type of EPROM that can be programmed repeatedly.
EPROM Allows program updates in the field without changing chips.
79. SELF DIAGNOSTICS - TECHNIQUES USED
RAM Checked by computing a checksum of memory contents and
comparing it against a stored factory value.
RAM Checked by periodically writing a specific data and
reading back the memory contents
A / D Checked by inputting a known value of + / - voltage.
Any off set at a given time, is software corrected.
SETTINGS Checked by checksums or CRC values can be stored and
compared. Often, 2 or 3 copies of settings are stored and
compared.
POWER Checked by monitoring power supply voltage values
SUPPLY from A / D converter.
80. FILTERS IN NUMERIC RELAYS
NEED FORE FILTERS
PROTECTIVE RELAYS MUST FILTER UNWANTED SIGNALS
AND HANDLE ONLY THOSE NEEDED FOR TRIP CALCULATIONS
Should be able identify and ignore :
- Switch yard noises
- Harmonics
- Exponentially decaying DC offsets
- CCVT Transients
- Reflections from travelling waves
- Capacitive series compensation
81. TYPES OF SIGNALS REQUIRED
FOR PROPER PROTECTION
Current, Voltage and Distance Relays :
Require fundamental frequency component signals.
All other signals will interfere with protection process.
Harmonic Restraint Relays :
Require both the fundamental & the Harmonic components ,
each value separately, for decision making process.
82. STANDARDS FOR RELAYS
• IS 3231 – 1986 Specification for electrical
relays for power system protection .
• IS 1885 – 1966 Electro-technical
PART IX Vocabulary, Electrical relays .
• BS 142 - 1966 Specification for electrical
protective relays.
• BS 3950 – 1965 Specification for electrical
protective system for a.c.plant .
• IS 8686 – 1977 Specification for static protective
relay.
• IS 9124 – 1979 Guide for maintenance and field
testing of relays .
83. STANDARDS FOR RELAYS
• IS 9124 – 1979 Guide for maintenance and
field testing of relays .
• IS 2705 Part I to IV Specification for
current transformers.
• IS 3156 Part I& II Specification for voltage
transformers .
• BS 3978 – 1973 Specification for current
transformers.
• IS 3842 1972 Application guide for elect.
relays