Model and stability analysis of grid-connected PV system considering the variation of solar irradiance and cell temperature

Abstract

In recent years, solar photovoltaic (PV) power technology has been applied widely. The interaction between the PV generator and the grid, however, may cause the stability issue and oscillation in practical applications. Hence it is very important to analyze the stability of grid-connected PV system. Due to the fluctuation of solar irradiance, the operating characteristics of the grid-connected system alter, and the grid-connected system shows different stability at the altered operating points. Therefore, it is vital to analyze the grid-connected PV system stability at all operating points in the entire operation range. The impedance-based analysis method is a useful tool for stability analysis of the system. However, since the operating point of the system often alters continuously, it is difficult to use conventional impedance/admittance model to characterize the system performance. To overcome this drawback, this paper attempts to incorporate the solar irradiance into the conventional PV generator admittance model and develops a multivariable small signal admittance model for PV generator. Moreover, the PV cell temperature influence is also considered in the model. Further, a new analysis method is proposed to enable the stability analysis. Simulation and experiment were conducted to demonstrate the effectiveness of the model and the stability analysis method.