Hierarchical Voltage Control Strategy in Multi-bus Islanded Microgrid Based on Secondary Voltage Control Bus Selection Method

To minimized steady-state voltage deviations throughout all load buses under random load disturbances, a selection method of the secondary voltage control bus (SVC-bus) for a multi-bus microgrid (MG) is proposed. The SVC-bus selection method is inspired by the pilot bus selection method in power system and takes the characteristics of MG into account. Moreover, in order to regulate the voltage magnitudes of the buses and improve the accuracy of reactive power distribution among distributed generators (DGs), a tertiary voltage control (TVC) strategy based on SVC-bus is proposed to achieve a compromise among three objectives: (1) minimizing multi-bus voltage deviations, (2) accurate reactive power sharing among droop-controlled DGs by making full use of surplus capacity of renewable energy DGs, and (3) minimizing line losses. The multi-objective function of TVC is solved by the primal-dual interior-point method. Finally, the feasibility of the SVC-bus selection method and the TVC strategy have been verified on a real-time experimental platform of RT-lab and PLC.