Effect of Grid-Connected Photovoltaic Generator on Dynamic Voltage Stability in Power System

The integration of grid-connected photovoltaic (PV) generation into a power system causes certain technical effects because the network design initially does not consider the integration of distributed generation. The rapid growth of PV module installations and high penetration of PV generation can cause many technical issues such as poor power quality and can impact on power system voltage stability. This study focuses on dynamic voltage stability analysis as well as determining the dynamic PV system parameters that affect dynamic voltage stability. The system models developed for dynamic voltage stability analysis consider the dynamic PV generator model and dynamic load. Time-domain dynamic voltage stability simulations consider factors such as intermittent solar radiation, line outage and dynamic load such as the induction motor. Simulations were performed at the maximum level of PV penetration; 2% for the IEEE 118 bus transmission system and 60% for the IEEE 69 bus radial distribution system. The results show that intermittent solar radiations due to cloud cover have an impact on voltage stability in the power system. The sudden drop in voltage causes dynamic voltage instability in which the bus voltage drops more than 6% of the allowable voltage deviation. Dynamic disturbances such as starting of the induction motor also affect voltage stability. Notwithstanding, islands are formed due to line outage at the line connected to the PV generator bus. Hence, the presence of the grid-connected PV generator and induction motor cannot help to maintain balancing of the bus voltage which can ultimately lead to voltage collapse.