Abstract: This paper proposes an improved voltage- restraint overcurrent protection method featuring coordinated regulation of pre-fault current and voltage. The core improvement lies in breaking through the traditional fixed-setting mode by introducing the dual variables of pre-fault current and point of common coupling voltage to build an adaptive regulation model. Through four-segment piecewise functions, the relay operating current threshold is dynamically calculated to achieve precise adaptation to fault level variations under different irradiance conditions. Additionally, voltage interval discrimination logic is incorporated to strictly comply with IEEE 1547 voltage ride-through requirements, with a 25 ms delay to block transient disturbances, achieving a balance between fault detection sensitivity and anti-interference capability.