Harmonics Elimination by Two-Leg Hybrid Filter Controlled by Modified Reference Frame in Distorted Load Conditions

Abstract

In the past few years, specifically after late 2019, a dangerous virus spread in the Republic of China called (SARS-Co This paper presents the performance of three-phase two-leg shunt hybrid power filter (SHPF) for quality improvement with distorted conditions of the nonlinear load. Shunt hybrid power filter (SHPF) are considered an attractive solution to overcome the problem of current harmonics generated by nonlinear loads. The hybrid filter used in this study includes two-leg inverter connected in series with passive filter tuned for 7th harmonic frequency. The passive filter is designed with three phase LC filters. The nonlinear load is a diode rectifier feeding a (Rd, Cd) parallel load. The current control strategy appropriate for filtering harmonics of an unbalanced nonlinear load in a three-phase three-wire power system. It is based on modified reference frame method which combine Self-Tuning-Filter (STF) with unit vector generation instead of Phase-Locked-Loop (PLL) circuit. As the power electronics equipment based non-linear loads generates harmonic currents that are the source of adverse effects, therefore, it is very important to compensate the dominant harmonics and thus Total Harmonic Distortion (THD) below 5% as specified in IEEE 519 standard. For the connection to the network no transformer is needed. Simulation results obtained by the MATLAB Simulink shows the efficiency and effectiveness of the filter to mitigate harmonic distortion and balance of the utility current with power quality improvement.