Short-Circuit Current Analytical Method for Photovoltaic Systems Considering Dual Closed-Loop Control Dynamic Characteristics

Accurate short-circuit current calculation is crucial for protection coordination and grid integration of large-scale photovoltaic (PV) plants, yet conventional methods often lack transient accuracy. Based on field tests under varying power and voltage-dip conditions, this study proposes an analytical short-circuit current calculation method for PV systems considering the dynamic characteristics of dual closed-loop control. The complete fault transient process is divided into distinct stages according to control mode switching and limiter actions. The method incorporates stage-wise active power balance and approximates the outer-loop current reference via linearization, enabling the derivation of transient fault currents through a second-order response solution to piecewise linear references. Validation with field measurements confirms that the proposed approach improves the accuracy of transient short-circuit current compared to traditional methods, providing a reliable basis for protection coordination and grid integration of large-scale PV plants.