An adaptive sampling-interval generator for digital relaying

Abstract

A method for measuring frequency at a fixed sampling rate is described, and a variable-rate method is introduced. An algorithm based on a digital Fourier transform, which locks the sampling frequency in a microprocessor-based system to the fundamental of an incoming voltage waveform, is devised. The algorithm also intrinsically provides a measurement of the frequency. The algorithm is applied to the case of a volt/hertz relay.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>