Fault time detection method of active distribution network based on Prony fitting and pixel comparison

In the application of relay protection in active distribution network, it is of great significance to accurately identify the fault time for system protection. However, the detection criteria of traditional fault time detection algorithms are mostly complex and easy to be affected by sampling frequency. Therefore, a fault time detection method based on pixel value comparison is proposed. Firstly, the fitting algorithm is used to fit the non-fault part of the fault recording signal, and the fitting expression is obtained and extended to the length of the original fault recording signal. Then, the extended signal is compared with the original signal image information to obtain the fault occurrence time. Finally, the simulation results show that the fault time detection algorithm has intuitive criterion, high accuracy and improves the time resolution. In the face of different fault types and fault positions, the detection error can be much lower than a sampling interval, so that the detection error can be controlled to the pixel level, and a certain transition resistance can be tolerated. It also has high detection accuracy for low sampling frequency.