Research On Dynamic Compensation Control Of Distributed Power Grid Based On Residual Generator

With the rapid development of the world economy and the acceleration of industrialization,the demand for energy is increasing day by day.Due to the advantages of abundant resources and pollution-free environment,renewable energy has developed rapidly in recent years.However,renewable energy has the characteristics of dispersed geographical location and various energy forms.Therefore,the use of distributed generation control technology can effectively utilize renewable energy.Distributed power grid is a typical application in distributed power generation technology,and it is also a key bridge between distributed energy and power grids.This paper mainly studies the power quality of bus in ac-dc hybrid distributed grid.The research contents include distributed grid modeling and power quality problem analysis,dynamic compensation control strategy based on residual generator,design of observer based residual generator,design of voltage dynamic compensation controller and secondary compensation controller,small signal modeling and stability analysis.The main contents and contributions of this paper are summarized as follow:The state space model of DC single converter,AC single inverter and DC multi converter in parallel is established for AC-DC hybrid distributed power system.The state space model takes the output signal of the control ring as the input signal and the output current as the disturbance signal.And the power quality of AC-DC bus voltage under load switching,power fluctuation of distributed power supply and unbalanced load access is analyzed.Then,for the power quality problem caused by the disturbance current,the dynamic compensation control structure based on the residual generator for single converter and the distributed dynamic compensation control structure based on the residual generator for multiple converters are proposed.After then,the observer-based residual generator and the distributed observer-based residual generator are designed respectively to obtain the residual signal when the system is disturbed.In order to eliminate the influence of the disturbance on the system,the voltage dynamic compensation controller for single converter and the distributed voltage dynamic compensation controller for multiple converters are obtained by using the model matching principle with the residual signal as input,and the secondary compensation controller is designed to suppress the secondary disturbance generated by the voltage compensation signal.In order to verify the stability of the control structure,the small signal models of single converter,single ac inverter and multiple dc converter in parallel are established,and the characteristic root method is used to analyze the stability of the system.Finally,based on the theoretical analysis,PXI Target Hardware-in-the-Loop experiment platform was used for experimental verification.The experimental results show that the control strategy proposed in this paper can effectively suppress the power quality problems caused by load switching,power fluctuation of distributed power supply and three-phase imbalance etc.,and ensure the stability of distributed power grid system.