Self-synchronization longitudinal current differential protection method suitable for power transmission line

Abstract

The present invention discloses a self-synchronization longitudinal current differential protection method suitable for a power transmission line. The method includes the following steps that: fault condition detection and fault time point extraction are realized according to the fault features of the line; with the fault time points of two ends of the protected line adopted as time reference, current data are synchronized, and therefore, excellent effects can be realized in the vicinity of a zero crossing point; and according to the influence of the reflection and reflection process of traveling waves, noise interference and the like, seven consecutive sampling points are detected, and it is confirmed that a fault occurs when at least four points change suddenly, and therefore, the reliability of protection and the precision of the time point of the fault are both guaranteed. The method of the invention does not depend on synchronous clocks and does not need to adopt extra equipment; and the method fully utilizes the fault features to realize the data synchronization, thereby reducing the transmission of time information. The method has the advantages of small communication traffic, high channel utilization efficiency, and the like, and can tolerate the influence of channel delay, sampling delay and the like.

Description

technical field [0001] The invention belongs to the field of relay protection for power system transmission lines, in particular to a self-synchronizing longitudinal current differential protection method suitable for transmission lines that does not require a synchronous clock. Background technique [0002] The transmission line has a wide coverage and a large geographical span, and its operating environment is complex and its working conditions are changeable. In actual operation, faults frequently occur on the transmission line and the fault range is easy to expand, which seriously affects the safe, stable and economical operation of the entire system. Therefore, sensitive and reliable protection devices must be equipped. The longitudinal current differential protection uses the current data at both ends of the line to form a differential criterion. It has excellent operating performance and absolute selectivity. It is often used as one of the main protections for EHV and...

AI Technical Summary

Problems solved by technology

Among them, the sampling time adjustment method based on the data channel, the sampling data correction method and the clock correction method require the same delay in the sending and receiving process, which is difficult to adapt to the multiplexing communication system with elastic load and variable routing; the satellite-based synchronization method has high precision and wide range of services. wide, but the technology is complicated and relies too much on satellite equipment, which is easily affected by satellite working conditions and has a huge range of influence

Images