Control Strategy Of Island Microgrid Inverter Based On H_∞ State Feedback Deadbeat Repeated Control

With the use of electric energy in various fields,the productivity has developed rapidly,and the social demand for electric energy is increasing day by day.Microgrid based on giving full play to the flexibility and advantages of distributed generation system has attracted extensive attention.In practical engineering applications,most of the loads carried in microgrid are nonlinear.When it is in the form of isolated island,due to the harmonic interference caused by nonlinear load,the power quality at the common coupling point of the system is seriously affected,so the stability and reliability of the system are reduced.To sum up,an H_∞state feedback deadbeat repetitive control strategy based on parameter filter droop control is proposed to improve the voltage quality of common parallel nodes of island microgrid and improve the system stability.By establishing the state space of the repetitive controller,the state feedback is introduced.Combined with H_∞control theory,the system stability is reconstructed into a convex optimization problem with a set of linear matrix inequality(LMI)constraints.Then the optimal gain of the controller is obtained to achieve high steady-state control accuracy and enhance the ability of anti-harmonic interference.Compared with the traditional repetitive control method using transfer function,this strategy can deal with the time-varying uncertainty caused by load change,and the solution process is less complex.The deadbeat control technology is introduced to improve the dynamic response speed of the system,quickly compensate the output voltage change caused by load change,and obtain better anti disturbance characteristics.The design of the H_∞state feedback deadbeat repetitive control is completed,and the comprehensive control law of the system is obtained.A virtual impedance droop control method based on parameter filtering is proposed to increase the accuracy of system power distribution and suppress system voltage offset,which avoids the harm caused by communication delay and improves the stability of the system.Finally,the proposed parameter filtering droop control and H_∞state feedback deadbeat repetitive control are simulated based on MATLAB/Simulink simulation platform,which proves the effectiveness and feasibility of the control strategy.