With effect from the academic year 2012-2013

EE526 Advanced Power System Protection

(Elective) Instruction : 3 Periods/Week

Duration of Univ.Examination : 3 Hours

Univ.Examination : 80 Marks

Sessional : 20 Marks

UNIT I Static relays- Comparators and static relay characteristics: Relays as comparators –

Amplitude and Phase comparison schemes – General equation for comparators for

different types of relays – Static comparators – Coincidence circuits – Phase splitting

methods–Hall effect comparators – Operating principles – Use of level detectors – Time

delay circuits – Filters – Thyristors – Triggering circuits and DC power supplies.

UNIT II

Static relay hardware: Operating principles: Static time current relays directional

units based on phase and amplitude comparison– Differential relays – Distance relays –

Quadrilateral relay – Elliptical relay – Relay response – Principle of R-X diagram –

Convention for superposing relay and system characteristics – Power swings, Loss of

synchronism and its effect on distance relays.

UNIT III Generator, motor and transformer protection: Generator protection against short

circuits using differential relays against inter-phase fault – Combined split-phase and

overall differential relays – Protection against stator open circuits – Rotor and Stator

overheating, Loss of excitation protection and field & ground fault protection. Digital

protection scheme based upon second harmonic current induced in the rotor field circuit.

UNIT IV

Transformer differential protection: Effect of magnetizing in rush currents –

Grounding transformers – Bus protection with differential relays. Line protection: 3 zone

protection using distance relays – Switched schemes – Auto-reclosing – Single and multi-

shot auto reclosing – Single pole and three pole auto reclosing.

UNIT V

Pilot wire and carrier protection: Circulating current scheme – Balanced Voltage

scheme – Translay scheme – Half wave comparison scheme – Phase comparison carrier

current protection –carrier transfer scheme – carrier blocking scheme – Digital protection

EHV/ UHV transmission line based upon traveling wave phenomena. Suggested Reading:

1. Badriram and Viswakarma D.N., Power System Protection and Switchgear — Tata McGraw Hill,

2004.

2. L.P.Singh, Digital Protection, Wiley Eastern Ltd., 1994.

3. Warrington A.R. Van C, Protective Relays ,Vol I & II Chapman & Hall, London and John Wiley &

Sons, 1977.

4. Mason C.R. The art and science of Protective Relaying, Wiley & Sons, 1956.