Control of distributed static compensator using extended structure-enhanced phase-locked loop-based algorithm under nonideal AC mains

Abstract

Summary In this paper, a 3-phase extended structure-enhanced phase-locked loop (ESEPLL)–based control algorithm is proposed for a 3-phase 4-wire DSTATCOM (distributed static compensator) at linear and/or nonlinear consumer loads. A major feature of this control algorithm includes accurate and adaptive estimation of instantaneous fundamental positive sequence components of load currents at nonideal AC mains. In a highly distorted and highly unbalanced grid supply voltages, conventional phase-locked loop technique fails to extract the required signals. In such situation, the ESEPLL technique is used for estimating the reference supply currents. The proposed scheme not only enhances the performance of DSTATCOM system but it also provides the instantaneous compensation of harmonics currents, reactive power, unbalancing, and neutral currents due to load behavior. A single unit of ESEPLL technique is used in a 3-phase system for desired performance with necessary mathematical analysis. The control algorithm is tested on DSTATCOM using DSP-d-SPACE1103 interface with MATLAB. The obtained test results on a developed prototype show that the proposed control technique succeeds to enhance the power quality at point of common interface under various loading conditions in full-scale voltage at distribution level.