Adaptive Virtual Impedance Control for Series Active Compensator to Improve PV Power Injection in Distribution Networks

With the increase of photovoltaic (PV) penetration in distribution networks (DNs), the overvoltage issue caused by reverse-active power and the high R/X ratio has resulted in serious PV curtailment, which has been an important challenge for the development of renewable energy. To overcome the above issue, this article proposes an adaptive virtual impedance control method based on series active compensators (SACs). The overvoltage issue is effectively mitigated, and the power injection capability of PV systems is improved. By using SACs, the equivalent R/X ratio of DNs at the fundamental frequency is reshaped to achieve dynamic voltage regulation. Compared with other compensation methods, the proposed method has a lower device capacity by constructing optimization equations for apparent power and output voltage based on virtual impedance. And the loss of PV power in feeder is reduced. The relationship between the R/X ratio and overvoltage is analyzed, and its safety threshold for solving overvoltage is obtained. The simulation and experimental results verify the effectiveness and correctness of the proposed method.