MITIGATION OF HARMONICS IN THREE-PHASE GRIDS USING ACTIVE POWER FILTERS: SIMULATION-BASED COMPARISON OF IRP AND SRF METHODS

The increasing use of nonlinear loads in electrical power systems has made power quality issues more pronounced, particularly in industrial facilities and electric vehicle charging infrastructures. These loads inject high levels of harmonic currents into the grid, leading to distortions in the voltage and current waveforms, reducing energy efficiency, shortening equipment lifespan, and adversely affecting system stability. In this context, effectively suppressing harmonics and improving power quality have become critical requirements for modern power electronics applications. Active Power Filters (APF) are advanced power electronic devices capable of performing functions such as harmonic suppression, reactive power compensation, and system protection against sudden load changes. In this study, instantaneous reactive power (IRP) theory, Synchronous Reference Frame (SRF), and Space Vector Modulation (SVM)-based control strategies for suppressing harmonics caused by nonlinear loads in three-phase systems are comparatively examined. The aim was to analyze the harmonic suppression performance, transient response, system stability, and implementation convenience of each method in the MATLAB/Simulink environment. The simulation findings serve as a guide for selecting control strategies for active power filters. They provided a comparative evaluation of the performance of the IRP, SRF, and SRF-SVM methods. Although the IRP method provided the best THD value (0.53%) under low-load conditions, the voltage stability was poor owing to the high overshoot (120 V) and long settling time (600 ms). The SRF method offered superior dynamic performance with a very short settling time (50 ms) and strong stability; however, its THD values (3.45%–3.57%) were high. The SRF-SVM method, on the other hand, demonstrated a balanced performance in terms of THD (2.34%–1.96%), overshoot (40 V), and settling time (200 ms), providing an optimal balance between harmonic suppression and transient response. Therefore, the SRF-SVM method was identified as the most suitable control strategy.