Wind-PV-Battery Based Microgrid with Discrete Three-Phase Frequency-Locked Loop Control

This paper presents a wind-photovoltaic (PV)-battery-based grid supported microgrid system. This system is developed to improve the power quality (PQ) and transfer the power to the loads and the grid. An improved discrete three-phase frequency-locked loop (DTP-FLL) GSC (Grid Side Converter) control is used to regulate the reactive power at the grid as well as to maintain the DC-link voltage of the GSC. Moreover, it improves power quality in different abnormal conditions. The rotor side converter (RSC) is used to provide the required amount of reactive power using the field-oriented control for the wind power generator (WPG). A doubly fed induction generator (DFIG) is used as a WPG. The tip speed ratio (TSR) algorithm is used to extract the maximum power from a wind turbine. A solar PV array with a battery is connected at point of common coupling (PCC), which is about a km far away from it. A battery management system (BMS) is used to charge and discharge the battery. According to the load demands at the microgrid, the BMS works in coordination with it. A PV feed-forward term is added with the total active component of the control, which damps out the dynamic changes into the system. The grid current THD (Total Harmonics Distortion) is also maintained within 5% according to the IEEE standard. Simulated results demonstrate performance of the microgrid in different conditions, such as variable speeds within the MPPT (Maximum Power Point Tracking) range of the wind turbine, performance of GSC and RSC, changes in PV array insolation, charging and discharging the battery are optimized using BMS at different circumstances. The grid current THD is maintained within 5% according to the IEEE-519 standard.