Power System Protection 001

Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Power System Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

S.A.Soman Department of Electrical Engineering IIT Bombay

Power System Protection

Introduction Power System Protection S.A.Soman

1

Overview Electrical Energy Systems Types of Protection

2

Relays Introduction Evolution of Relays

3

Circuit Breaker What is a circuit breaker?

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Summary

Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Introduction Power System Protection S.A.Soman

1

Overview Electrical Energy Systems Types of Protection

2

Relays Introduction Evolution of Relays

3

Circuit Breaker What is a circuit breaker?

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Summary

Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays

Electrical Energy is Generated at few kV and stepped up.

Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Transmitted through AC and HVDC lines. Stepped down and distributed at load centers. Its natural mode of synchronous operation knits the system together.

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Why do we need protection? Electrical apparatus operates at various voltage levels and may be enclosed or placed in open. Under abnormal operating conditions protection is necessary for Safety of electrical equipments. Safety of human personnel.

Introduction Power System Protection S.A.Soman

1

Overview Electrical Energy Systems Types of Protection

2

Relays Introduction Evolution of Relays

3

Circuit Breaker What is a circuit breaker?

4

Summary

Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems

Types of Protection Apparatus Protection

Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

System Protection

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Types of Protection Apparatus Protection Transmission Line Protection Transformer Protection Generator Protection Motor Protection Busbar Protection

System Protection

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Types of Protection Apparatus Protection Transmission Line Protection Transformer Protection Generator Protection Motor Protection Busbar Protection

System Protection Out-of-Step Protection Under-frequency Relays Islanding Systems Rate of Change of Frequency Relays

Introduction Power System Protection S.A.Soman

1

Overview Electrical Energy Systems Types of Protection

2

Relays Introduction Evolution of Relays

3

Circuit Breaker What is a circuit breaker?

4

Summary

Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

What is a Relay? A relay is a logical element which process the inputs (mostly voltages and currents) from the system and issues a trip decision if a fault within its jurisdiction is detected. Inputs to a relay are Current from a current transformer. Voltage from a voltage transformer.

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Introduction Power System Protection S.A.Soman

1

Overview Electrical Energy Systems Types of Protection

2

Relays Introduction Evolution of Relays

3

Circuit Breaker What is a circuit breaker?

4

Summary

Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Evolution of Relays If we zoom into a relay, we can see three different types of realization: Electromechanical Relays. Solid State Relays. Numerical Relays.

Introduction Power System Protection

Electromechanical Relays

S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

First generation of relays. Uses the principle of electromechanical energy conversion. Immune to electromagnetic interference and rugged.

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction

Solid State Relays These relays were developed with the advent of transistors, operational amplifiers etc. Their functionality is through various operations like comparators etc. Their advantages are

Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

More flexible. Self checking facility. Less power consumption and low burden. Improved dynamic perfomance characteristics. High seismic withstand capacity. Reduced panel space.

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Numerical Relays Operation of a numerical relay involves analog to digital conversion of voltage and currents obtained from VT and CTs. These samples are fed to the microprocessor or DSP where the protection algorithms process these signals and necessary decisions are taken.

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Its advantages are Maximum flexibility. Provides multiple functionality. Self checking and communication facility. It can be made adaptive.

Introduction Power System Protection S.A.Soman

1

Overview Electrical Energy Systems Types of Protection

2

Relays Introduction Evolution of Relays

3

Circuit Breaker What is a circuit breaker?

4

Summary

Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

What is a Circuit Breaker? A circuit breaker is basically a switch to interrupt the flow of current. It opens on relay command. It has to handle large voltages and currents. The inductive nature of power system results in arcing between the terminals of a CB. CBs are categorized based on the interrupting medium used.

Introduction Power System Protection S.A.Soman Overview Electrical Energy Systems Types of Protection

Relays Introduction

Summary Necessity of a protection system.

Evolution of Relays

Circuit Breaker What is a circuit breaker?

Summary

Types of Protection. Three generations of relays. Role of circuit breakers.