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Protection Schemes and Different Types of Relays SVS Sathyanarayana Dy.Manager POWERGRID, Kadapa 400 KV S/S Phone :91- PowerPoint Presentation
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Protection Schemes and Different Types of Relays SVS Sathyanarayana Dy.Manager POWERGRID, Kadapa 400 KV S/S Phone :91- - PowerPoint PPT Presentation


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Welcome. Protection Schemes and Different Types of Relays SVS Sathyanarayana Dy.Manager POWERGRID, Kadapa 400 KV S/S Phone :91-8562-231256, Cell:9440002222 Email: svssai@sancharnet.in. PHILOSOPHY OF PROTECTION.

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slide1

Welcome...

Protection Schemes and Different Types of Relays

SVS Sathyanarayana

Dy.Manager

POWERGRID,

Kadapa 400 KV S/S

Phone :91-8562-231256, Cell:9440002222

Email: svssai@sancharnet.in

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

philosophy of protection

PHILOSOPHY OF PROTECTION

A. To maintain proper operation in electrical power system we must hold together the various areas of the power system.

Due to geographic location of generating stations practically all produced electric energy is transmitted over transmission & sub- transmission lines and this is the reason why operational reliability of the transmission networks is of vital importance.

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

philosophy of protection3

Simultaneous faults

  • Interline faults

T

R

T

R

R

S

R

S

S

T

S

T

Phase

selective

tripping ?

PHILOSOPHY OF PROTECTION

The transmission lines are the most widely spread part of the power system and overhead lines are the least protected from environmental influences.

The number of line faults is consequently very high compared to the number of faults on the other elements of the power system.

The reliability & security of power transmission line largely depends on protection system.

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide4

FUNDAMENTAL PRINCIPLES OF PROTECTIVE RELAYING

1.Two groups of relaying is necessary

a. Primary relaying – First line of defense

b. back up relaying – functions only when primary relaying fails.

2. Primary relaying may fail because of failure in any of the following:

a. Current or voltage supply to the relays

b. DC Supply

c. Protective relaying

d. Tripping circuit

e. Circuit breaker

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide5

PRIMARY RELAYING

Generator Protection

Low voltage SG

Protection

Power Trans.

Protection

High voltage SG

Protection

Transmission line Prot.

High voltage SG Protection

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide6

REQUIREMENTS OF PROTECTIVE RELAYS

  • Any relaying equipment must be sufficiently sensitive so that it will operate reliably when required under actual condition that produce the least operating tendency.
    • SENSITIVITY : The relay shall be sensitive to operate for minimum quantity of operating parameter.
    • SELECTIVITY: The relay/scheme should be able to select the faulty section and isolate.
    • SPEED : The relay should operate faster so that fault is isolated as fast as possible.
    • STABILITY : The Relay should be stable.
    • RELIABILITY: The relay/scheme should operate for all types of faults with repeatability and reliability.
    • COST: The relay/scheme should be economical .

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide7

B

VALUE

PRICE /

UNIT

COST

A

RELIABILITY

REQUIREMENTS OF PROTECTIVE RELAYS

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide8

ELEMENTS OF PROTECTION

  • Fault Clearance: CBs
  • Fault Sensing: Relays
  • Inputs to Relays
  • CT: For sensing Currents
  • VT: For sensing voltages
  • DC supply: For functioning of relays & CB
  • Diagnostic Equipment: DRs, EL, FL

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

elements of protection
ELEMENTS OF PROTECTION

Bus

Trip Ckt

CB

CT

Current

DC SOURCE

Voltage

CVT

Relay

Feeder

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

types of relays and their characteristics
Types of Relays and Their Characteristics

What is a Relay?

  • A device which has an electrical / non-electrical quantity as input
  • Output is in form of a switch called “Contacts”, which either close or open depending on the input quantity

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

a simple relay
A Simple Relay

Solenoid

Input

Armature

Normally Open Contact

Normally Close Contact

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

basis of classifications
Basis of Classifications
  • Quantity of response: Voltage, current, frequency, power etc.
  • Function: Detection, time-delay, tripping, alarm, signaling, flag, contact multiplication etc
  • Construction: Electromagnetic, Static or Numerical

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

basic types based on operating principle
Basic Types Based on Operating Principle
  • Attracted Armature
  • Moving Coil
  • Induction
  • Thermal
  • Motor-Operated
  • Mechanical
  • Static
  • Numerical

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

limitations of electro mechanical relays
Limitations of Electro-Mechanical relays
  • Requiring high aux power
  • High burden on CTs / PTs
  • Bulky
  • Difficult to obtain complex characteristics
  • Prone to drift in characteristics
  • No facility for monitoring
  • Limited range of settings

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

application based classifications
Application based classifications
  • Directional O/C & E/F relays
  • Distance relays
  • Differential relays
  • Over-flux relays
  • Pilot-wire relays
  • Phase comparison relays etc..

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

directional o c e f relays
Directional O/C & E/F relays

IDMT Characteristics

PSM x Current

TMS x Time

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

directional o c e f relays17
Directional O/C & E/F relays
  • Direction sensing is achieved by giving voltage input from PT / CVT
  • Widely used as back-up protection for power transformers

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

distance relays
Distance relays
  • Basically measure impedance with voltage and current inputs
  • Most widely used as primary / back-up protection for transmission lines as well as back up protection for shunt reactors

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide19

DISTANCE RELAY ZONES

Z3

Z2

Z1

X

X

X

X

X

X

BASIC SETTING PHILOSOPHY

ZONE –1 : 80 % OF PROTECTED LINE

ZONE –2 : 100 % OF PROTECTED LINE + 20 % OF SHORTEST

ADJ LINE SECTION OR 100% + 50% OF TR IMP

ZONE –3 : 100% OF PROTECTED LINE + 100 % OF LONGEST ADJ LINE SECTION or 100% OF TR IMP

CHECK SHOULD BE MADE FOR REACH TO TRANSFORMER ADJ TO PROTECTED LINE.

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

differential relays
Differential Relays

I1

I2

i1

i2

id=(i1-i2)

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

differential relays21
Differential Relays

Stabilization is achieved by:

  • Biasing
  • High Impedance in Diff ckt

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

over flux relay
Over-flux relay
  • Used to protect transformers against over-fluxing condition
  • Measures V/f

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

pilot wire relays
Pilot-wire relays
  • Used for protection of feeders
  • Works on differential relay principle
  • Current information of other end is carried by pilot wires
  • Economical only for very short lines

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

phase comparison relay
Phase comparison relay
  • Makes use of carrier (PLCC or others)
  • Sends phase information of current to other end
  • At each end phase information of both the ends is compared.
  • If both ends indicate current flow to the line, an in-zone fault is inferred

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

phase comparison relay through fault
Phase Comparison Relay(Through fault)

A

B

A

B

B

A

No Trip

A+B

A+B

No Trip

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

phase comparison relay in zone fault
Phase Comparison Relay (In-Zone fault)

A

B

A

B

B

A

Trip

A+B

A+B

Trip

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

phase comparison protection
Phase Comparison Protection

Un-Affected by :

  • Heavy load transfer
  • Power swings
  • CT saturation
  • CT Phase errors

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

phase comparison protection28
Phase Comparison Protection

Limitations:

  • Cannot be used on long lines
  • Affected by Capacitive currents

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide29

TYPES OF TRANSMISSION LINE PROTECTIVE RELAYS

  • IMPEDENCE BASED RELAYS (Distance protection)
  • Electromagnetic : MM3T Scheme-(YTG 31 based)
  • Static : Michromho, Quadromho,RAZFE,LZ96,THR
  • Numerical :REL100, REL 316, REL521, EPAC, MiCOM, SIPROTEC,SEL
  • PHASE COMPARISION RELAY
    • P-10, P-40
  • VOLTAGE BASED RELAYS
  • RXEG21,VTU21

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide30

POWER TRANSFORMER PROTECTION

The Power Transformer is one of the most important links in a power transmission and distribution system. A Transformer fault will cause a large interruption in power supplies and the impact is more serious than a transmission line outage and also cause damage to power system stability.

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide31
Transformer protection falls under two major categories :
  • Protection of the system against the effects of faults arising inside the transformer.
  • Protection of the transformer against the effect of faults occurring on any part of the system (external).

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide32

TRANSFORMER FAULTS

HV

LV

MV

LV CB

R

Y

B

N

MAIN TRANSFORMER

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide33

FAULTS INTERNAL TO THE TRANSFORMER

  • Earth faults
  • Phase to Phase faults
  • Inter turn faults
  • Core faults
  • Tank faults

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide34

EXTERNAL SYSTEM CONDITIONS:

  • Over-load
  • System faults (phase to phase/ phase to earth)
  • Over voltage
  • Reduced system frequency.

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide35

NORMAL PROTECTIONS FOR TRANSFORMER

  • Differential Protection : DTH31,RADSB,RADHA
  • Ground Fault Protection : CAG14, RADHD
  • Over Current Protection : CDD,RXIG
  • Over Load Protection : VTU,RXEG
  • Over Fluxing Protection : GTT,RATUB
  • Buchholz Relay (OLTC & Main Tank)
  • Pressure Relief Device
  • Oil and Winding temp alarms and trips
  • Oil Level Monitoring (MOLG)

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

transformer differential
Transformer Differential

R

Y

B

Differential relay

BIASWinding

Main CTs

R

Second

Harmonic

Restraint

Y

B

Aux CT

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide37

Transformer Differential

Bias

3.0

Operate

2.0

Differential Operate Current

Non-Operate

1.0

0.2

1.0

2.0

3.0

4.0

Through Bias Current

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

restricted earth fault protection
Restricted earth fault protection

64

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

evolution graph
EVOLUTION -GRAPH

ELECTRO MAGNETIC

STATIC

EFFECTIVE

COST

DIGITAL

NUMERICAL

FUNCTIONS

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide40

EVOLUTION OF NUMERICAL RELAYS

ELECTRO MAGNETIC

E/M

MICRO

PROCESSORS

ANALOG

Static Analog

A to D

Converter

Digital

Static Digital

Trip

Coil

Micro Processor

A to D

Converter

Static Numeric

Software

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide41

Technology comparison for Protective Relays … continued

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

technology comparison for protective relays
Technology comparison for Protective Relays

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide43

Technology comparison for Protective Relays … continued

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide44

Technology comparison for Protective Relays … continued

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide45

Technology comparison for Protective Relays … continued

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD

slide46

Thank You

POWER GRID CORPORATION OF INDIA LTD – SECUNDERABAD