An Improved Control Strategy for Active Power Injection and Power Quality Enhancement in a Low-Voltage Weak-Grid Integrated PV and Battery System

This article presents an improved control strategy for enhancing active power injection and power quality (PQ) in a low-voltage weak-grid integrated PV and battery system (LWPB). The proposed method effectively estimates both sinusoidal and non-sinusoidal reference quantities, thereby improving active power injection and multiple PQ compensations simultaneously. By computing reference and load power based on fundamental voltage and load current components, and employing an optimal rating for the interlinking converter based on power angle and voltage gain, the system maximizes converter capacity to perform multiple functions efficiently and reliably. The PV system is connected to the DC bus through a boost converter with an MPPT-droop integrated controller, ensuring maximum power extraction during power deficits and acting as a droop controller during power surpluses. This configuration enables seamless bidirectional power flow between AC and DC by regulating the DC bus voltage. Unlike conventional controllers that enhance either PQ or renewable integration, leading to reduced converter utilization and higher costs, this strategy optimizes converter rating, improves utilization and efficiency, and significantly reduces costs. The proposed system was validated using a prototype laboratory testbed, with experimental results demonstrating exceptional performance across a wide range of operating conditions. The hardware results confirm the system’s effectiveness in harmonic suppression, power factor improvement, reactive power compensation, and compensation for unbalanced effects caused by non-linear and highly inductive loads under different conditions.