Implementation of SOGI-EPLL for DVR Control Under Unbalanced and Distorted Grid Conditions

Currently, electricity supply networks are 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 a requirement for robust control algorithms which must include a precise controller capable of extracting accurate grid’s phase angle, frequency, and voltage magnitude to ensure 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, addressing the limitations of the commonly used synchronous reference frame based phase-locked loop (SRF-PLL), which fails to extract phase angle and frequency accurately. The proposed method enhances harmonic rejection and DC offset elimination by introducing a magnitude normalization loop, enabling better performance under grid distortions. It shows improved transient behavior with lower frequency overshoot (50.13–50.27 Hz) and faster settling time (10–30 ms) as compared to conventional PLL methods. The proposed SOGI-EPLL system also demonstrates the dynamic response and enhanced stability during unbalanced grid conditions, makeing it more efficient solution for DVR control.