Experimental Investigations on Photovoltaic Interface Neutral Point Clamped Multilevel Inverter-Based Shunt Active Power Filter to Enhance Grid Power Quality

Abstract

In this research study, a photovoltaic (PV) interface three-level Neutral Point clamped (NPC) voltage source inverter-based three-phase Shunt Active Power Filter (SAPF) has been proposed. Initially, the major power quality issues, such as compensating for reactive power, minimizing Total Harmonic Distortion (THD) of source current, improving power factor, and injecting the PV system’s energy into the electrical power system, are discussed. Later, a multilevel NPC inverter-based SAPF was developed to address power quality concerns by utilizing the Synchronous Reference Frame Theory (SRF) and Adaptive Neuro Fuzzy Inference System (ANFIS) algorithm. The reference current required for the compensation is calculated using the SRF theory, and the ANFIS algorithm is implemented to generate a smooth DC link voltage. In addition, a Hysteresis Current Controller (HCC) is employed to provide the required switching pulses for the neutral point clamped voltage source inverter, thereby reducing the THD produced by Nonlinear (NL) loads, which can be balanced or unbalanced. The SAPF efficiently utilizes the active power generated by PV arrays. It employs an Enhanced Incremental Conductance (EINC) based MPPT controller to maximize power extraction of PV arrays into the power grid. Additionally, it supports load-reactive power demand and improves grid power quality by eliminating harmonics. The performance of the proposed system is validated using both hardware and MATLAB simulation. From the experimental results, it is observed that the proposed system exhibits better performance by minimizing the harmonics and maintaining the DC link voltage constant under balanced and unbalanced NL load conditions.

Keywords

• Neutral point clamped converter
• FPGA
• power quality
• photovoltaic system
• ANFIS
• shunt active power filter