Optimal control of source–load–storage energy in DC microgrid based on the virtual energy storage system

Abstract

By integrating controllable source-load in the form of virtual energy storage into the energy storage control system within the DC microgrid, the virtual energy storage system (VESS) with flexible resources can provide a viable solution for the system to effectively accomplish the co-optimization of source–load–energy storage. Firstly, based on the conversion relationship between the rotational kinetic energy of the wind turbine and asynchronous motor and capacitive energy storage, the wind turbine and desalination load are established as virtual energy storage equivalent models; as electric vehicles have both mobile load and energy storage characteristics, the tariff mechanism is used to develop an orderly charging and discharging model to establish a virtual energy storage model for electric vehicles. Secondly, the economic optimization model of the VESS is established jointly with source–load–storage to maximize the intra-day microgrid operation gain, and an energy cooperative optimization control strategy is formed with virtual capacitance value and virtual charge state as operating parameters in each period of time. Finally, it is verified through simulation that the source–load–storage​ energy co-optimization control can not only relieve the regulation pressure of energy storage in the DC microgrid but also significantly improve the operation economy of the microgrid.