Performance improvement of shunt active power filter under variable grid frequency condition using complex coefficient filter‐frequency locked loop

Summary Synchronizing methodology for shunt active power filter (SAPF) based on the resonant controller using generalized integrator (GI) in the stationary reference frame is of great interest for researchers now a day. In this paper, a phase synchronizing technique based on the complex coefficient filter (CCF) embedded with a frequency locked loop (FLL) is proposed for the fundamental active and reactive component extraction of load current and unit template generation from grid supply. The proposed CCF‐FLL–based control works effectively under varying grid frequency, distorted and unbalance grid voltage conditions to generate the reference source current at a unity power factor for proper harmonic compensation using an indirect current control method. In this work, a detailed mathematical modeling for development of control logic for CCF‐FLL is done, and its feasibility with the bode plot is also confirmed. Simulation for SAPF is performed using both CCF and CCF‐FLL–based control strategy separately to judge the performance of each. Simulation confirms that the proposed CCF‐FLL based control is capable of maintaining the source current with low total harmonic distortion (THD) as per the IEEE‐519 standard with the nonlinear load. The effectiveness of the proposed controller for desired harmonics compensation is also validated through real‐time simulation using OPAL‐RT OP4510 platform. In this article, the synchronizing capability of CCF‐FLL is tested under varying grid frequency conditions. It is observed that CCF losses the synchronization in perturb condition which led to shutting down of whole SAPF network due to compensation current overshoot. SAPF operation with CCF‐FLL is following the IEEE‐519 standard under variable frequency condition along with distorted and unbalanced grid supply. A comparative study of CCF and CCF‐FLL shows the requirement of FLL under perturbing condition.