Microprocessor-based UHS relaying for distance protection using advanced generation signal processing

UHS (ultra high speed) refers to operating times of less than 5 ms on 50 Hz power systems. Three distinct types of UHS relaying realization in distance protection via advanced-generation digital signal processing, possible with cheap and readily available VLSI chips, are considered. Type I is the correlator detector: Type II and III are the spectrum and cepstrum analyzers, respectively. The performance of these detectors is evaluated with respect to varying system configurations that complicate the post fault signals. Microprocessor implementation of these techniques show that 5 ms limit is achieved in Type I and II detectors, whereas the Type III detector can operate in 3 ms