Research on the control strategy of interlinking converters for photovoltaic storage hybrid microgrid

Abstract

This article mainly solves the problem of accurate power distribution and stable running in the photovoltaic storage hybrid microgrid and studies different control strategies of the interlinking converter connected to the AC-DC subnet under on-grid and off-grid conditions. The relationship between DC-side voltage, active power and active current is analyzed in the on-grid, and the DC voltage stability is supported by using a closed-loop voltage and current; in the off-grid mode, an improved bidirectional sag control method based on unitization processing is adopted, in which the power to be transmitted by the converter is differed from the actual value as the reference input of the current loop on the traditional double sag control, which can coordinate the power transmission between subgrids more precisely; And the action threshold is designed for the problem of repeated switching of converter operating modes. The results of simulation show that the converter able effectively to judge the magnitude and power direction in both parallel and off-grid operation modes, which ensures the normal operation of the important loads inside the subnets on both sides, thus verifying the feasibility of the control method.