The invention provides an equivalent method suitable for a current collection network in internal faults of a wind power plant and belongs to the technical field of power system modeling. Aiming at the problems that the equivalent method for the current collection network is only suitable for external faults of the wind power plant in the equivalent modeling process of an existing wind power plant, and the existing equivalent method for the current collection network cannot set a fault point in an equivalent model when the faults appear in the wind power plant, a method for determining the position at which an equivalent unit is connected to the current collection network through nonlinear programming without changing the structure and the parameter of the current collection network is provided. When the internal faults appear at different positions, only a cluster division result and the position at which the equivalent unit is connected to the current collection network need to correspondingly adjust. The method can be applied to equivalent modeling in internal faults and external faults of the wind power plant, so that the equivalent model has a broader application range.