1. School of Electrical and Electronic Engineering, North China Electric Power University, Beijing 102206, China; 2. China Electric Power Research Institute, Beijing 100192, China

A fast online identification algorithm for delayed feedback load based on V-I characteristics is studied. According to the principle of constant load capacitance and electricity sensibility of the electrical equipment, the steady periodic current before every transient is extracted with the same voltage. And the periodic current of the last electrical equipment is obtained by the one-dimension addition and subtraction of the signal. Then, combining the operation habits of the residential users to impose constraints on the target function, the combination range of the electrical devices that may be switched can be reduced. Finally, the load status in the power network is determined by optimization. The impact of the load transient process on the steady state feature extraction can be avoided by the delay identification of the switching load. The public datasets are used to verify the effectiveness of this method, and the start/stop time can be judged accurately and efficiently in a short time by load delay identification.