Solar PV integrated simplified multilevel inverter configuration for power quality improvement using multilayer Gamma filter

Abstract

Power quality (PQ) issues have intensified due to the rapid integration of renewable sources into the utility grid. An effective control strategy is imperative to address these problems. This paper proposes a novel approach by replacing conventional 2-level inverters with a simplified 5-level multilevel inverter (SMLI) as a shunt active power filter (SAPF) unit. The SMLI exhibits superior performance, including low total harmonic distortion in voltage, reduced electromagnetic interference, and enhanced system flexibility. Further, a multilayer Gamma filter is utilized to control SAPF and extract fundamental component from nonlinear load. The developed control not only improves the power factor at the supply end but also resolves other PQ issues. The novelty of the paper is the innovative utilization of the Gamma filter and closed loop implementation of SMLI system which can operate effectively in two modes, viz. during day and night. Furthermore, the system is also tested under partial shading conditions. The solar PV array integrated at the DC link of the SMLI supplies the load during the daytime. However, at night, when the solar PV array’s power is unavailable, the load’s demand is met solely by the grid. The SAPF functioning ensures an improvement in power quality. The proposed and developed Gamma filter control action performs quick adaptive estimation under diverse load profiles. Furthermore, reduced memory requirement during operation guarantees optimal performance under dynamic circumstances involving fluctuating solar irradiation and load parameters. The OPAL-RT real-time simulator has been used to both simulate and experimentally validate the results. The application of this research is extensively useful in grid-connected PV system for enhancing PQ issues in distribution systems with integrated renewable energy sources.