Designing, Testing and Implementation of System Protection Schemes (SPS) in Assam Power System as a First Line of Defense Against Constraints in Transmission System Elements

Abstract

Maintaining system reliability is one of the foremost concerns of any transmission sector utility. Certain constraints in the transmission system elements e.g. lack of N-1 redundancy in power system elements, constraints in loading capabilities of transmission lines, transformers, etc. may lead to undesired system conditions where the stability of a wide area of the transmission system network may be at stake. The modern IEC 61850 compliant IEDs (Intelligent Electronic Devices) can perform fast, accurate and extensive logical decisions with respect to prevailing system conditions. The capability of the IEDs can be extensively used to design wide area SPS (System Protection Schemes) to protect and preserve the reliability, security, and integrity of the grid during abnormal system conditions. The following paper describes the designing, testing and implementation of various SPS in the Assam power system network which have proved to be successful in preserving the stability of the grid. The SPS has been designed utilizing the present protection and communication system of AEGCL (Assam Electricity Grid Corporation Limited) with a primary focus on reduction in additional hard wirings, reduction in additional cost involvement, efficient use of IEC 61850 features of the IEDs and designing a fail proof scheme with efficient control and monitoring features