Sharing Control Strategies for a Hybrid 48V/375V/400Vac AC/DC Microgrid

This paper studies the sharing control scheme for a Hybrid 48V/375V/400Vac AC/DC Microgrid, considering reliability as one of the key factors. For that purpose, different possible paths for energy flow provide redundancy to the grid. However, this redundancy leads to the need of enhanced coordinated control systems that can enable these alternative paths for the energy flow. In this paper, both the dc and ac grids are controlled by a P/V droop strategy. At the ac grid, this assumes a main resistive component in the distribution line impedance. The droop control voltage error in steady state is compensated by a novel and simple secondary control approach. The proposed control strategy is based on the calculation of the optimum power flow in each operating point and the real-time modification of the droop characteristics of the converters involved in the power flow calculation. The proposed control is also capable of eliminating the induced voltage drop when using virtual impedance and incorporating any power sharing criteria for the converters contributing to the power production.