Estimation of the Instantaneous Values of the Electrical Operating Parameters in the Ac Network1

Abstract

The problem of determining the instantaneous values of the electrical operating parameters for the purpose of investigating dynamic processes in nonlinear systems is considered. It is shown that existing procedures for calculating the parameters, which provide a sampling rate of the output data equal to the operating frequency period, does not enable the value of the parameters to be estimated at an arbitrary instant of time with high accuracy. A method of determining the instantaneous values of the electrical operating parameters is proposed, based on a modified Hilbert transformation. An example of the determination of the frequency, amplitude and phase of the current when there is a short circuit is presented. The results enable phenomena occurring “within” the period of the industrial current frequency to be investigated, and also enable the dynamic characteristics of power systems to be determined more accurately.