Stochastic analysis in the time domain of very high speed digital distance relays. II. Illustrations

For pt.I see ibid., vol.141, no.3, p.161-8 (1994). In part I of the paper, a time-domain approach to the stochastic analysis of very high speed digital distance relays was introduced. The analysis was founded on state-space modelling and on time-domain filtering theory. In part II, the theoretical framework of part 1 is applied to the evaluation of impedance algorithms based on phasors estimated through discrete Fourier transforms and Kalman filters. This is done for a set of different sampling rates, prefilters and operating schemes. A power system is introduced for which variable configurations are used to simulate 80 case line faults for each fault type, with the electromagnetic transients program. The analysis of the algorithms is performed upon the sample variances of the fault-induced transients, yielding basic results about their performance. Next, the effect of other signal distortions is investigated, and further results are obtained.<>