Control Strategy for Smoothing the Microgrid Tie-line Power Fluctuations Based on Back-to-Back Converter

The microgrid system is connected to the distribution network through the point of common coupling. The change of power of micro sources and the load will cause the power fluctuation and the voltage rise at the point of common coupling in the distribution network. In order to improve stability of the microgrid operation connected to distribute network, the power flow fluctuations are smoothed. In this paper, a microgrid flexible grid-connected interface circuit using a back-to-back dual converter with banding energy storage battery on the DC side is proposed. According to the characteristics of a small range of terminal voltage changes in the charging and discharging process of the battery are used, a DC voltage follow-up control based on DG power change in the microgrid is adopted in the distribution network side converter, and a control scheme for flexible grid connected interface system is also proposed. A simulation model is built that microgrid connected to distribute network using the flexible interconnection interface, and the conditions of micro power supply without output, power generation and power fluctuation in microgrid are simulated. The simulation results show that the control strategy effectively suppresses the power fluctuations of point of common coupling, guarantee the stability of voltage.