99. Digital Protection for Power Systems

Computer relaying play a major role in power system protection, since they offer many advantages. While DSP based protection systems play a very important role in power systems – namely in Cost efficiency, Functional flexibility, Self checking capability, and Adaptive relaying features – the traditional methods for relay setting co-ordination consist of using standard relay packages supplied by major manufacturers, and to adapt these standard packages to every protection scheme. This has led to compromises – since it is not possible to optimize a standard relaying system to every protection need. With the advantage of generally available hardware and software, having the speed and capability of DSP circuitry necessary for protection application, it has now become possible for the relay engineer to develop and implement custom protection solutions for those applications where standard packages may not provide the necessary flexibility or performance. Open relaying is a concept in which different applications adopt a generic piece of hardware and are capable of implementing all of the relaying functions with a capability to expand as the need arises. Prototype Digital Signal Processor (DSP) based relays have been successfully implemented and are currently called PT relays, for the protection of power transmission lines. Development of Algorithms for the Digital Signal Processor (DSP) based relays, helped design a suitable algorithm for the specific application with more relay hardware to run such an algorithm. In this paper, a Digital Signal Processor based multi-function relay for power system protection is discussed. And design, development, and implementation aspects of DSP based protection are described.