DSOGI-PLL and Moving Average Filter Based Control Method for Shunt Active Power Filter

Abstract

 The increasing penetration of nonlinear loads and power electronic converters in modern power systems has led to a significant rise in current harmonics and power quality problems. The shunt active power filter (SAPF) has emerged as an effective solution to mitigate these issues. However, the performance of SAPF systems largely depends on the accuracy of the reference current generation method and the effectiveness of the synchronization algorithm. In conventional synchronous reference frame (SRF–dq) based SAPF control methods, low-pass filters (LPFs) are commonly used to extract the fundamental component, while high-pass filters (HPFs) are employed to obtain harmonic components. Nevertheless, these filtering structures may introduce undesirable effects such as time delay and phase shift, which degrade the dynamic performance of the control system.In this study, an improved dq-based control strategy is proposed for SAPF applications by combining a Dual Second-Order Generalized Integrator Phase-Locked Loop (DSOGI-PLL) based synchronization technique with a Moving Average Filter (MAF) based harmonic extraction approach. In the proposed method, the DSOGI-PLL structure ensures accurate phase angle estimation even under distorted grid conditions, while the MAF structure enables the extraction of the fundamental current component without introducing the delay and phase shift problems associated with conventional LPF and HPF filters. The effectiveness of the proposed control method is evaluated through simulation studies under different operating conditions. In the case of sinusoidal grid voltage and nonlinear load, the total harmonic distortion (THD) of the source current is reduced from approximately 19.19% to 0.79%. Furthermore, under distorted grid voltage and nonlinear load conditions, the source current THD values decrease to the range of 1.55–1.89%. These results demonstrate that the proposed method significantly enhances harmonic mitigation performance and ensures compliance with the limits specified in the IEEE 519-2014 standard.