With the merge of new energy in which a large number of power electronic equipment are used in the traditional power system

the harmonics of power grid is increasingly more and high requirement to the quality of filter device of power system is raised.For improving the dynamic and static quality and robustness of active power filter further

in this paper a kind of repetitive-H infinity composite control strategy based on repetitive control strategy is proposed.The delay chain in the repetitive control is regarded as external disturbance of the system

generalized state space expression based on the repetitive controller and the APF mathematical model is set up

to transfer the solving process of compensation in the repetitive control loop into a standard H-infinity of a class of linear systems.Linear matrix inequality（LMI） method is used to design the optimal H-infinity controller so to avoid such problem as difficult solution by the traditional repetitive control stability compensator.It is shown by the simulation result that the proposed method is feasible and effective and

compared to the traditional repetitive control strategy

can improve effectively the dynamic and static characteristics of APF.