A line longitudinal differential protection method based on current zero-crossing for synchronization

Abstract

The present application discloses a line longitudinal differential protection method based on current zero-crossing point for synchronization, including: detecting and classifying the zero-crossing point of the current before the fault; after the protection starting element acts, selecting a zero-crossing point as a reference point, and virtualizing a zero-crossing point The sine wave is used as the reference phasor; the amplitude and phase of the current phasor are calculated with the virtual reference phasor as the reference; the time difference between the current sampling time and the reference point is used as the time label; the amplitude, phase and time of the current phasor are included The current information of the current side of the label and the zero-crossing point type is sent to the opposite side; the current information of the current side and the opposite side is compared, and the current information of the opposite side is processed; the current information of the current side and the opposite side with the same time tag is used to calculate the differential current and Braking current to achieve synchronization of current on both sides. The present invention is not affected by the inconsistency of the delay of the receiving and sending channels, has low requirements on the communication rate and channel performance, is not strongly dependent on the longitudinal channel, and has the advantages of strong economy and high reliability.

Description

technical field [0001] The invention belongs to the technical field of power system relay protection, and relates to a line longitudinal differential protection method for synchronization based on current zero-crossing point. Background technique [0002] The longitudinal current differential protection has the advantages of stable protection range, high sensitivity, fast action speed, and little influence by the change of system operation mode. It has been widely used in high-voltage transmission lines. However, the correct action of the pilot current differential protection is premised on the precise synchronization of the current on the current side and the opposite side. [0003] The traditional differential protection synchronization method is based on the data channel for synchronization, which requires consistent delay of the receiving and transmitting channels, high channel performance requirements, complex technology and high cost, which limits the application of lo...

AI Technical Summary

Problems solved by technology

[0003] The traditional differential protection synchronization method is based on the data channel for synchronization, which requires the delay of the receiving and sending channels to be consistent, and has high requirements for channel performance. The technology is complicated and the cost is high, which limits the application of longitudinal current differential protection in distribution network lines.

In addition, the traditional longitudinal current differential protection sends current instantaneous value information to the opposite side, which transmits a large amount of information and data, and requires high communication speed, which increases the construction cost

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