Design of systematic parameter tuning approaches for multiple proportional-resonance AC current regulator

Multiple proportional-resonance (MPR) AC current regulator is widely applied in inverter-interfaced distributed generation (DG) systems for selective grid harmonic and unbalance current compensation due to its effectiveness (i.e. desirable stability and dynamic response) and ease of implementation. However, the parallel MPR controllers interact with each other and create unwanted couplings, which degrades the system´s stability and control performance (i.e. tracking). In the literature, most of research works only consider tuning of the control parameters for fundamental current, while few studies are dedicated to the tuning of control parameters for harmonic proportional resonance (PR) controllers and the interactive influences among them are not fully taken into account. Therefore, it is necessary to tune the control parameters for each individual PR controller in a systematic way such that the stability (phase margin) of the whole control system is guaranteed, and at the same time the tracking performance for each individual controller is achieved. In this paper three systematic parameter tuning approaches for MPR current regulator are analyzed and one is identified as optimal practical solution.