Injection Impact of Photovoltaic Distributed Generations (PVDG) on Power Distribution System Stability

Utilization of photovoltaic power plants on distribution system has been widely used in many countries. Commonly, the photovoltaic system has been injected to the distribution system and called as photovoltaic distributed generations (PVDG) through medium or low voltage levels. The injection of the PVDG on the distribution system has been claimed to improve the voltage profile and reduce power losses. However, the good performance of the distribution system in term of the steady-state point of view, cannot directly guarantee to give a good response during the system disturbed. Therefore, to show the impact of the PVDG injection on power system stability is concerned in this paper. The size of the power injection and location of the injection site that have been determined by using the optimization technique, are then analyzed based on three scenarios, each of which represents the PVDG injection of 2x0.5MW, 4x0.5MW, and 6x0.5MW respectively at different bus locations. The voltage-, frequency-, and rotor angle-stabilities are analyzed to show the dynamic impact of the PVDG during three-phase fault condition. The analysis results indicate that the second scenario gives the best response in term of the rotor angle-, frequency-, and voltage-responses during dynamic conditions which supplies active power around 28.78% of the total load. The PVDG injection power in the first scenario (14.39% of total load) and also in the third scenario (43.18% of total load) would result in rotor angle and frequency responses with more oscillations being compared to the second scenario. However, the system dynamic responses for all scenarios show damped oscillations to reach the steady-state conditions.