Optimal control of single-phase microgrid with photovoltaic and energy storage for improving operation performance and seamless state transition

Abstract

Under voltage sags, swells, stochastic load profiles and harmonic voltage distortion, conventional synchronisation mechanisms often fail to track the grid voltage immediately and accurately, leading to degraded control performance and potential power quality violations. Maintaining high power factor operation becomes critically important in polluted grid scenarios. To ensure stability under these challenging conditions, this paper focuses on maintaining balanced and accurate unit templates with a minimal phase delay and stable DC link voltage in the presence of unpredictable grid scenarios. The synchronising transfer switch provides smooth transitions between the grid-connected and islanded modes of operation, enhancing both power quality and system reliability. The optimisation of distributed energy resources to improve grid resilience, stability and overall efficiency of renewable energy integration is presented in this work. The key element of this integration is a multi-functional voltage source converter with a unique control strategy, enabling precise control over the charging and discharging processes of the battery. The system exhibits versatile capabilities, including harmonic mitigation, reactive power compensation, and seamless supply of active power to the grid. Performance assessments highlight the controller's ability to improve microgrid stability and smooth operational transition capabilities.