Optimal planning of renewable energy source and energy storage in a medium- and low-voltage distributed AC/DC system in China

As the quantity of DC load and distributed generation system increases in China, AC/DC distribution system is arousing more and more research interest for its high-efficiency distribution ability. In this study, the optimal size and location of renewable energy source (RES) and energy storage in a medium- and low-voltage distributed AC/DC system is studied. A modelling method for the optimisation of such hybrid AC/DC system is developed. The objective of the proposed optimisation method is to minimise the life cycle cost of the system with consideration of the life span of RES. The planning method is based on energy balances and constraints of system operation. The utility requirements and subsidy in China for such system are also considered in the planning process. The method is demonstrated in a 10kV and low-voltage distributed AC/DC system considering installing photovoltaic system, wind turbines, and electric storage system. The provided results indicate that the method is effective and applicable for the optimisation of the size and location of RES in distributed AC/DC system. The life cycle cost of such system is significantly reduced with the subsidy of the Chinese government compared with the system without RES.