Distribution System Voltage Management with SVR and Multi PV Systems

In traditional Var control methods, inverters have to absorb reactive power for daylong to eliminate voltage rise caused by PV power. While, with the existence of the step voltage regulator (SVR) in a distribution network, the potential overvoltage problem can be eliminated by a few SVR tap operations. Consequently, the responsibility of Var control method can be changed only to reduce voltage fluctuations. In this paper, an innovative local Var control method is developed for voltage fluctuation alleviation in real time. Compared with traditional local Var control methods (e.g. Q-P curve), the Var support burden of inverters can be significantly reduced in the proposed method. In addition, due to less reactive power injection, less line loss (save around 20%) can be expected and smaller inverter capacity is required. On the basis of this local method, a global scheme is established for coordination among PV inverters. Specifically, the Var support burden will be redistributed among inverters by the global method with a certain time interval (communication time delay). Numerical results have proved the effectiveness of the proposed model, and future reactive power support design for distributed PV systems can benefit from this research.