A Control Strategy for Three-Phase PV-Grid Inverter with Active Filtering under Various Load Conditions

A unified dq-frame-based control strategy for a three-phase grid-connected photovoltaic (PV) inverter that serves as a flexible power-conditioning device is presented in this study. The proposed technique enables a multifunctional inverter design to simultaneously inject active power, reduce harmonic current, and compensate for reactive power. This differs from earlier systems that required multi-conversion structures or independent active power filters. The method is governed by the synchronous reference frame. It uses the DC link's instantaneous power balance to regulate the flow of bidirectional active power when there is either too much or too little PV power. The load current is divided into its basic and oscillating components using the dq-frame instantaneous power representation. Because of this, it can handle loads that are not straight lines or that combine curves and straight lines. Only the reactive and harmonic currents fluctuate, and the grid interface's unity power factor. The proposed approach has been tested under a wide range of conditions, including nonlinear, capacitive, and inductive loading. The findings demonstrate that regardless of how the system is configured, the grid current remains sinusoidal and in sync with the grid voltage. Additionally, the inverter side has very little harmonic distortion. These findings demonstrate that adding features that directly enhance the power quality of grid-connected PV inverters is simple and efficient with the suggested control framework.