Study On Control Problem Of Microgrid System Based On Optimization

With the development of microgrid technology,more and more renewable energy and energy storage devices are integrated to the microgrid.Due to the randomness and intermittent of renewable energy generation,the stability of microgrid system will be seriously affected when connected to the grid,and the frequency will deviate from the prescribed value.Considering that there are still active power disturbance and output constraints in the microgrid system,it is necessary to propose corresponding frequency control methods to ensure the safe operation of microgrid system,so that the frequency can be quickly stabilized even in the presence of disturbances.Firstly,the impact of photovoltaic(PV)on the frequency control of the microgrid is considered.In order to reduce the impact of PV grid-connected,a neural network observer is used to predict the power generation of PV.At the same time,the integral sliding mode control method is applied to design the frequency controller for adjusting the output power of the generator.The simulation is carried out on an island microgrid system to verify the effectiveness of the proposed observer-based integrated sliding mode controller.Secondly,the effect of EV on frequency control is analyzed in an EVs-integrated microgrid system.Since the EV has rapid response to frequency deviation,a novel hierarchically adaptive control strategy is developed including both the primary controller and the EV controller when power mismatches happen.The sliding mode primary controller is used to control the output power of generator,while the EV controller is designed by using adaptive dynamic programming(ADP)to control the charging power and the discharging power of EVs.Simulation is performed by comparative studies to demonstrate the excellent performance of hierarchically adaptive frequency control.Finally,the influence of wind power generation system on the frequency control of microgrid system is studied.The pitch angle control controller is designed for the wind turbine generation system to reduce the impact of wind power on grid-connection.And an adaptive composite frequency controller is proposed to adjust the frequency deviation.The effectiveness of the composite controller is verified by simulation analysis in the wind power microgrid system.