Abstract: The integration of a large number of power electronic devices into power system has changed the fault characteristics of power grid, which challenges the adaptability of the conventional relay protection excited by synchronous machines. The complex fault transient characteristics and short duration in power electronic system limit the application and development of passive detection protection technologies. The controllable ability of power electronic devices can improve the ability of fault identification of relay protection. The key technology of detective fault identification method is proposed based on the coordination of control and protection. Different types of power equipment that can realize the active detection are classified. Then the feasibility of the injection operation and the physical limitation of the injected detective signal are described. Finally, the application scenarios of the detective fault identification methods are discussed and the research prospect is given.