A Review on Protection of Transmission Lines

The growth of a country is scaled by the amount of energy it consumes. In the developing India, with the rise of population, increasing number of cities and demanding villages, caused to set up transmission lines with higher capacity. Inter-ties were connected through the transmission lines to lighten every city and village, thus making the whole system complex. This complex system required a robust protection, so that a fault in one place does not cause the unfaulted region to trip or series of trip undesirably, which may otherwise cause a situation of blackout. To protect the power system, we use protective relays-electromechanical, solid state or microprocessor relays. In this paper, different types of protections are discussed. The traditional protection schemes requiring a communication between two ends are discussed which include directional comparison blocking (DCB), permissive overreaching transfer trip (POTT), International Electrotechnical Commission (IEC) – 61850 to protect a transmission line using Generic Object Oriented Substation Events (GOOSE) messaging. At the process and station control levels, IEC 61850 define the rules for integration of protection, control, measurement and monitoring functions within a power system network. Successful tests were done by various manufacturers and utilities for substation automation using IEC 61850 proving enhanced interoperability between vendors and systems and elimination of substation wiring. Thus endeavors are now being directed to cover substation to control center and substation to substation automation using IEC-61850. Keyword: International Electrotechnical Commission, permissive overreaching transfer trip, Generic Object Oriented Substation Events.