Implementation of SOGI-EPLL for DVR Control under Unbalanced and Distorted Grid Condition

Abstract

Currently, electricity supply network is likely to encounter significant voltage distortions due to the extensive penetration of nonlinear loads into the grid. For safeguarding sensitive loads from these distortions and unbalanced grid conditions, a commonly employed solution is dynamic voltage restorer (DVR) with battery storage. For effective control over DVR, there is requirement of robust control algorithms which must include a precise controller capable of extracting accurate grid’s phase angle, frequency, and voltage magnitude which ensures that the reference DVR voltage is correctly determined. Therefore, a newly designed second-order generalized integrator (SOGI) based Enhanced Phase Locked Loop (EPLL) is proposed as the commonly used synchronous reference frame based phased locked loop (SRF-PLL) which fails to extract phase angle and frequency accurately. In order to check the effectiveness of proposed technique in terms of performance, the obtained results through MATLAB simulation are compared with SRF-PLL, SOGI PLL, Dual SOGI PLL and EPLL on various six cases of unbalanced grid conditions like: voltage sag, swell, harmonics and variation in fundamental frequency to mitigate the nonlinearities. Among the above techniques, proposed technique has shown its superiority under unbalanced grid conditions with lowest frequency overshoot of (50.13-50.27 Hz) and fastest settling time (10-30 ms).