Frequency adaptive proportional + multi-resonant output voltage control strategy for parallel operating distributed generation units

This paper presents a multi-loop control strategy for parallel distributed generation (DG) units in standalone mode of operation. Indeed, an Adaptive Proportional plus Multi Resonant (Adaptive P+MR) controller is designed for the voltage control loop and a simple Proportional regulator is used for the inner current loop. The proposed frequency adaptive control structure is also prorogued to parallel inverters with decentralized power sharing controllers thanks to the frequency adjusting property of the proposed multi-loop control strategy. A co-simulation is carried out combining Matlab/Simulink and PSIM environments in order to highlight the effectiveness of the global control structure which ensures high tracking performance with reduced total harmonic distortion (THD), deals efficiently with load disturbances and may face large frequency deviation while maintaining an accurate power sharing among the parallel DGs units.