Mitigation of interharmonics in PV systems: A cyber‐physical co‐regulation based maximum power point tracking algorithm

Current interharmonics caused by gird-connected PV systems have been noticed. From previous research, there is a trade-off between the interharmonic emission and tracking performance. In cyber-physical co-regulation systems, there also exists a trade-off between the cyber resource consumption and system performance. Motivated by this coincidence, a cyber-physical co-regulation based P&O MPPT algorithm is proposed for a three-phase single-stage grid-connected PV system to mitigate the interharmonic emission in this paper. In this algorithm, a cyber-physical model is built in which the sampling frequency is seen as the cyber state, and the step size is considered as the physical state. Based on the model, cyber and physical control laws are proposed in which the cyber and physical states are used to regulate each other. To apply the control laws, guidelines for designing control coefficients are also proposed based on the limits on the cyber and physical states to avoid chaotic behaviors caused by P&O MPPT characteristics. Compared with another mitigation algorithm without considering the cyber-physical characteristics, the proposed algorithm can reduce the peak amplitude of the interharmonics by about 50% with a 1.35% cyber resource utilization savings and a 0.35% power efficiency improvement.