HARMONIC AND REACTIVE POWER COMPENSATION USING A DUAL VSI IN NONLINEAR LOAD CONDITIONS

Abstract

The increasing penetration of nonlinear loads in power systems has led to a significant deterioration in power quality, characterized by harmonic distortion and poor reactive power balance. This paper presents a novel dual voltage source inverter (DVSI) topology designed for simultaneous real power injection and compensation of harmonics and reactive power in grid-connected systems. The configuration consists of a Main VSI (MVSI) for delivering active power from distributed energy resources (DERs) and an Auxiliary VSI (AVSI) functioning as a dynamic compensator. The proposed control scheme employs Instantaneous Reactive Power Theory (IRPT) and synchronous reference frame (dq0) transformation to accurately extract and compensate harmonic and reactive components in real time. A decoupled control strategy enables independent regulation of power flow and compensation currents without affecting the stability of the grid or the DER. Simulation results in MATLAB/Simulink demonstrate the system’s ability to reduce Total Harmonic Distortion (THD) below 3%, maintain near unity power factor, and ensure voltage stability under highly distorted and unbalanced load conditions. The proposed DVSI-based compensation approach offers improved dynamic performance, reduced DClink voltage stress, and scalable integration for smart grid and microgrid applications