Abstract: Based on the steady-state current verification protection of line air charging, the magnitude and direction of steady-state capacitive current are calculated based on the length, structure, and voltage level of the line, and the estimated steady-state capacitive current is used to verify the polarity of the protection device by impacting the full voltage of the line. This method can achieve current verification protection to ensure the polarity of the protection device and ensure the safe and stable operation of the power grid.