Abnormal Time Synchronization Detection of Substation IED based on Frequency Deviation

The occurrence of abnormal time synchronization in smart substation will cause the clock pulse deviation of secondary system to normal time synchronization, affecting the normal operation of secondary equipment, especially relay protection devices. But there is still lack of efficient algorithms for detecting abnormal time synchronization. To improve the accuracy and speed of abnormal time synchronization detection, at first, the signal frequency is calculated by matrix-pencil filter quickly and accurately and frequency deviation is obtained by subtracting the actual value of signal frequency. Then the relationship between the clock pulse intervals of the substation, the sampling interval and the signal frequency are studied and the calculation formula of the time synchronization deviation is derived. On this basis, a substation abnormal time synchronization detection algorithm based on frequency deviation is proposed. When the deviation is larger than the set threshold value, the abnormal time synchronization can be accurately detected and the time synchronization deviation will be calculated, which can provide necessary information for the calibration of the secondary device and locking of relay protection. It is verified by simulation that this algorithm can accurately detect abnormal time synchronization in a time window of 1ms in case of time synchronization deviation is larger than. It has high detection accuracy and precision, and can meet the requirements of relay protection for high precision of time synchronization.