New Algorithms for Computer Relaying for Power Transmission Lines

Abstract

Synopsis This paper presents a new recursive discrete-time filter for calculating the impedance from digitized voltage and current samples from the relay location, The transmission line voltage and current signals during a fault are modelled as a sum of decaying dc, and components of fundamental frequency and higher harmonic frequency components. The recursive discrete-time filter interpolates the signal samples and generates filter coefficiencs either by using spectral observation or functional expansion techniques. Both the algorithms are tested by using the fault data recorded at the Saskatchewan Power Corporation producing fast and reliable tripping conditions.