Optimal Distributed Power Allocation for Isolated DC Microgrids Based on Projected Subgradients

In this paper, an island DC microgrid composed of wind energy conversion system (WECS), photovoltaic system (PVS), storage battery and electric loads is investigated, and an optimization strategy based on Distributed Projected Subgradient algorithms (DPS) is proposed to solve the problem of power distribution among distributed power sources. First, wind power is used as the main source of power generation and photovoltaic is used as the secondary source, and batteries are used to adjust the power when needed to meet the load demand and maximize the utilization of wind power generation as much as possible, and to improve the charging and discharging process of batteries. To achieve this goal, the DPS algorithm is used to optimize the three subsystems locally, and the power reference values of each subsystem are obtained through information exchange and iterative updating. Then, the local controller adjusts the operating state of each subsystem according to the power reference value to achieve the overall optimized operation of the system. Finally, through simulation analysis, it is proved that using DPS algorithm to deal with the power optimization problem of isolated DC microgrid can well achieve the goals of balancing load supply and demand, making full use of wind power and photovoltaic power generation, extending battery life, and reducing system operation cost.