Comparison of Two Coordinated Control Strategies Designed for Unbalanced Microgrids in Low Voltage Distribution System

摘要

Microgrids are usually characterized by unbalance due to the integration of single-phase distributed generators (SDGs)/loads (for example rooftop photovoltaic (PV) system) and asymmetrical faults. In such an unbalanced microgrid, load power sharing control and voltage regulation become more challenging. Conventional primary and secondary control approach could not be applicable to this type of microgrids. This paper proposed 1) a phase-independent virtual synchronous generator (P-VSG) primary controller, 2) a distributed secondary power sharing controller, and 3) a distributed secondary voltage containment regulator used for voltage restoration. The proposed control allows for independent and flexible power and voltage control for each phase, accurate phase shifts, and can guarantee admissible voltage profiles, resulting in better operation security and reliability. The simulation results verify the proposed control method and show that better control performance is achieved compared to conventional primary and secondary control method.