An SO-SOGI based control for a three-phase DVR under distorted grid conditions including DC offset

Abstract

This paper introduces a simple and effective control algorithm for generation of reference voltages based on Three-phase dual SO-SOGI (Second Order-Second Order Generalized Integrator) based Phase Locked Loop (PLL) for DVR (Dynamic Voltage Restorer). The proposed DVR scheme is implemented to achieve faster compensation of voltage sag, swell with and without phase jump and at harmonic conditions. Three-phase PLL is used to extract the phase information and amplitude to control and to inject the required voltage at the load end. The SO-SOGI based QSG (Quadrature Signal Generation) and PLL are found effective in mitigating inter-harmonics, harmonics, DC-Offset and unbalance in the estimated parameters. This enables the DVR with the proposed control algorithm to inject reference voltage accurately under linear/ non-linear load conditions. In this paper, SO-SOGI is chosen because of its dynamic response, tracking accuracy and faster detection under all varying grid conditions within a very short duration of time. The control algorithm is tested and evaluated using MATLAB/Simulink and has proved its effectiveness.