In order to analyse the effect of photovoltaic grid system on the voltage stability in the background of renewable energy power generation , this paper comes up with a method which using photovoltaic grid system replaced with a generator to join in the system.In this method ,the photovoltaic (pv) and second order equivalent generator model is established ,and the voltage of single machine infinite system is analyzed with the change of the load.In order to fully understand the role of photovoltaic power generation on the system voltage stability,the voltage change of the generator and the pv model with the change of load is studied, and the influence of output voltage of the generator and the photovoltaic (pv) on the system is also discussed.In the final ,this paper analysis the effect of output capacity of photovoltaic separate on the voltage of the system when the voltage is stable.Results show that the photovoltaic replacing the equivalent generator, except for its own characteristics, can enhance the system voltage stability.
