Non-linear auto-disturbance rejection control of parallel active power filters

There are many uncertainties and unmodelled dynamics in active power filters (APFs) because loads may vary all the time and the high switch frequency of solid-state devices has not been modelled in detail so far. Considering the difficulty of creating an accurate mathematic model for APF, auto-disturbance rejection control (ADRC) is an alternate non-linear robust method, which is fully based on the system inputs and outputs. The design procedure for an ADRC controller of parallel APF systems is proposed and discussed. Three main parts of ADRC are analysed and the adjustment of the controller parameters is discussed in details. Furthermore, simulation and experiment are carried out to prove the dynamic performance and robustness of the proposed controller. The result proves the validity of the control strategy. The analogue signal detected in the ADRC controller is less than in the other control strategies.