Application Of Virtual Motor Technology In Electric Energy Router

Electric energy router is the energy hub and control center of microgrid.It not only provides different interfaces to realize the interconnection and integration of distributed power supply,energy storage device and AC / DC load,but also carries out the mutual transformation of various forms of electric energy to control the size and direction of energy flow.The topology of the power router,the characteristics of the converter and the dispatch and distribution of the power have an important impact on the stability,reliability and economy of the microgrid operation.In this paper,the power router is taken as the research object,focusing on its topology and the control strategy of AC / DC interface converter.In view of the problem that the AC interface inverter controlled by VSG with fixed parameters can not take into account both the rapidity and the stability at the same time,an adaptive control strategy of virtual moment of inertia is proposed.According to the frequency variation and frequency rate of change,the control strategy adjusts the moment of inertia in two directions;when the frequency deviation is small,the moment of inertia takes a smaller value to ensure the rapidity of system regulation;when the frequency deviation is large,the moment of inertia takes a larger value to reduce the frequency rate of change and improve the stability of system regulation;when the frequency rate of change changes,the moment of inertia takes a smaller value to make the frequency The rate quickly approaches the rated frequency.Compared with the traditional VSG control simulation,it is proved that the proposed VSG control strategy can meet the requirements of system stability and effectively improve the speed of frequency regulation.In order to improve the inertia and damping of DC subsystem,virtual DC motor control is introduced into the voltage current double closed-loop constant voltage control of the energy storage interface converter based on the mechanical equation and electromotive force balance equation of DCmotor.The effectiveness of the proposed method in improving the dynamic stability of DC bus is verified by comparing with the traditional non inertial control simulation.Aiming at the problem that the capacity of energy storage device is limited,which may lead to overcharge,two working modes of maximum power point tracking and constant power point tracking of photovoltaic power generation unit are designed.The working modes of photovoltaic power generation unit and energy storage battery are determined through logical judgment,so that the photovoltaic unit can independently control power generation when the charging is limited.The simulation results show that the proposed control strategy is correct and effective.