A new digital filter for identification of symmetrical components in power system

This article presents a novel algorithm for identifying and measuring the symmetrical components of three phase voltage or current waveforms in electrical power systems. The problem is formulated as an estimation problem and presented in state space form. A particle swarm optimization (PSO) is employed to minimize the error associated with the estimated parameters. The proposed algorithm is used to estimate the positive, negative and zero components of unsymmetrical waveforms. Application of the proposed algorithm has been conducted on various test cases, among which a practical simulated power system has been implemented in Simulink using its power system block set. Various abnormal scenarios were carried out (such as line to ground, line to line to ground, as well as unbalanced load) in order to create realistic situation of unsymmetrical waveforms. Different factors affecting the identification process, such as data window size, sampling frequency, and the number of samples, are studied. Effects of bad data on the solution accuracy are also considered. Results obtained show that the proposed technique efficiently estimates the symmetrical components of three phase unbalance voltage or current waveforms.