Research On Stability Control Of DC Micro-grid With Nonlinear Disturbance Observer

As the energy crisis and environmental pollution problems have become more serious,clean,renewable wind and solar energy have received widespread attention.But distributed power sources are vulnerable to natural resources.To solve this problem,the distributed power supply,load and energy storage devices are combined into a relatively stable micro-grid.However,when the DC micro-grid encounters large power disturbances,the system may fail to operate normally.Therefore,current feedforward is used to improve the transient stability of the system.First,this paper takes the photovoltaic power supply,storage battery and three-phase load DC micro-grid as the research object,establishes its mathematical model,analyzes and designs the access methods of each component,and verifies the accuracy of the model taken by simulation experiments.Second,for the traditional double closed-loop control cannot effectively suppress power fluctuations,a current feedforward path of nonlinear disturbance observer output is set in the double c losed loop to improve the trans ient stability of the system.Theoretical analys is and MATLAB simulation show that the control strategy can reduce the voltage change and shorten the voltage recovery time.Finally,the three-phase unbalanced load connected to the system is studied.This load will cause the battery-s ide current to contain the secondary ripple current component,affecting the stability of the system.In response to this problem,a control method for adding a notch filter to the outer loop and the current feedforward path is proposed.At the same time,the impedance analys is method was used to analyze the two control strategies to suppress the secondary ripple current,and the effectiveness of the strategy was verified by MATLAB simulation experiments.