A novel algorithm applied in the transient saturation of current transformer

Serious distortion in the secondary current is caused by the transient saturation of the current transformer (CT). Operation performance of relay protection will be influenced severely. An improved Prony's algorithm that can be applied in relay protection for anti-saturation is presented in this paper. In the improved Prony's algorithm, characteristic roots corresponding to 50Hz are preset to improve the calculation accuracy in short time window. Then, in order to reduce the calculation amount, singular value decomposition (SVD) is used to determine the valid order of the signal, and reasonable sampling rate division is adopted with the determined valid order. In use of the unsaturated segment of the CT's distorted secondary current, the improved Prony's algorithm can obtain effective information of the fault current in a relatively short time window. Calculation results of the experiment data proved the validity of the improved Prony's algorithm.