Abstract: With the continuous consumption of fossil fuels,our environmental protection awareness,science and technology is developing, and renewable energy has received more attention. Distributed renewable energy system have become a key object in integrated energy utilization. Based on Roy Billinton test system (RBTS) model, a hydrosolar complementary distributed power system was designed to meet the electricity demand of a city along the Yangtze River. PowerFactory software was taken to make optimized analysis on power grid configuration.Considering the practical cases,the cost minimization method is used to study the marginal cost varied with load and the maximum profit point of the power system,which can provide a reference for the government to set electricity price.And with the goal of line safety, possible faults were tested and analyzed to ensure the safety of the operation of the overall power grid.

Key words: distributed renewable power system；Roy Billinton test system；photovoltaic power generation device；hydropower units；configuration of grid；marginal cost；electricity price, hydroksolar complementation, comprehensive energy system