Simplified Model of Distributed PV Generation and Influence Analysis on Load Characteristics

With a large number of distributed PV generation (DPVG) integrated into the distribution network, the equipment composition in the load region changes significantly as well as the overall dynamic characteristics of the load region. Therefore, the DPVG must be considered in load modeling. The detailed model of the PV generation system is complex and has many parameters, which is not easy to be combined into the existing composite load model. Therefore, a simplified DPVG model is proposed which uses the controlled current source to represent the DPVG system and only retains the active power control loop. The number of the model parameters is reduced to three including the two coefficients of a PI controller and an equivalent impedance of distribution lines. The simulation shows that with high DPVG penetration, the active power fluctuation of the entire load region increases significantly under voltage sag comparing to the pure load of the same power, while the reactive power fluctuation decreases after the fault is cleared. Therefore, it is not appropriate to directly subtract the DPVG power from the load power when modeling the load region with a high proportion of DPVG. A separate DPVG model must be combined into the model of the load region with a high DPVG proportion.