Impact of dynamic behavior of photovoltaic power generation systems on short-term voltage stability

In this study, we investigate the impact of the dynamic behavior of photovoltaic (PV) power generation systems on short-term voltage stability of the transmission system. First, the impact of the fault ride-through capability of a PV model is studied by setting several recovery speeds of the active current output when the operation of the PV system is interrupted because of a voltage sag. The results are analyzed by using transient P-V curves and a stability boundary, which has been proposed in our previous research. Further, we show that the installation of PVs severely impairs the short-term voltage stability if the PVs shut off after a voltage sag, and its recovery speed is low. Next, two countermeasures to control short-term voltage instability phenomena are tested. One is the operation of the PV system at a leading power factor in the normal state, and the other is the dynamic reactive power control by the inverters of the PV system after a voltage sag. Numerical examples are carried out for a one-load infinite-bus power system and a five-machine five-load power system. The results show that these countermeasures can play a substantial role in preventing the voltage instability phenomena caused when a PV system is suddenly interrupted because of a fault.