Distributed Secondary Control of Hybrid AC/DC Microgrid Based on Improved Model-free Adaptive Control

To solve the problems that the existing distributed secondary control (DSC) of AC/DC microgrid is greatly influenced by the parameters of the primary control, the communication topology of DSC is complicated, and the secondary control parameters are difficult to set, etc., DSC of hybrid AC/DC microgrid based on improved MFAC (MFAC-DSC) is proposed. In this paper, the dynamic linearization parameters of distributed generation are estimated online by using the historical sampling data, and the traditional DSC’s problem of being easily affected by the primary control parameters is solved. In order to deal with the issue of the interlinking converter communication failure, the communication network and control strategy of DSC is optimized through no communication interlinking converter. Besides, the convergence of the MFAC-DSC control system is derived, and the stable convergence condition is given. Based on a real AC/DC microgrid experimental platform, the feasibility of MFAC-DSC is verified under various operating conditions. Compared with the traditional DSC strategy, the MFAC-DSC method can effectively reduce the power fluctuation caused by the change of distributed generation’s droop coefficient, and the droop coefficient can be adjusted on a larger scale. Meanwhile, it solves the problems of control failure and bus voltage offset caused by the interlinking converter communication failure. ©2024 Chin.Soc.for Elec.Eng.