Applying pattern recognition in distance relaying. II. Feasibility

For part I see ibid., vol.139, no.4, p.301-5 (1992). In part I, the limitations of the existing operating characteristic of distance relays were mentioned. With increasing interconnection between power systems, it has become necessary to avoid relay maloperation and obtain operating characteristics adaptive to an operation of the overhead line being protected by it. In part II, the result of applying pattern recognition in designing distance relays with adaptive operating characteristics is reported. In proposing this approach, the stochastic nature of the power system is acknowledged. The purpose is to obtain a near-optimal operating characteristic matching the performance characteristic of the overhead line the distance relay is to protect. A further advantage obtained by this approach is that the distance relay can be organised to generate an online database or learning set which can be further used to tune the operating characteristic and prevent maloperation under stringent duty conditions