Fixed value selection method for bridge arm overcurrent protection of flexible direct current power transmission system

The invention relates to a fixed value selection method for bridge arm overcurrent protection of a flexible direct current power transmission system, and aims to solve the current situations as follows: there is no a unified method for fixed value selection for bridge arm overcurrent protection of a direct current protection apparatus of the flexible direct current power transmission system; and if the selected fixed value is not matched with the bridge arm overcurrent function in a valve-control apparatus, maloperation or failure to operation of the direct current protection apparatus are caused. Therefore, a method is selected as follows: a broken line of a C point and a C point on the valve-control apparatus and a broken line of a P point, a P point, a P point and a P point on the direct current protection apparatus are drawn on a current time diagram; whether the fixed value is matched or not is judged by judging whether there is a crossed point or not between the two broken lines; the crossed points are