Line longitudinal differential protection method for synchronization based on current zero crossing point

Abstract

The invention discloses a line longitudinal differential protection method for synchronization based on a current zero crossing point. The method comprises the following steps: detecting the zero crossing point of a current before a fault and classifying the zero crossing point; after the protection starting element acts, selecting a zero crossing point as a reference point, and virtualizing a sine wave as a reference phasor; calculating the amplitude and phase of the current phasor by taking the virtual reference phasor as a reference; taking the time difference between the current sampling time and the reference point as a time label; sending the current information of the side including the amplitude and the phase of the current phasor, the time label and the zero crossing point type to the opposite side; comparing the current information of the current side and the current information of the opposite side, and processing the current information of the opposite side; calculating the differential current and braking current according to current information of the local side and the opposite side with the same time label, and achieving the synchronization of current on the two sides. The method is not influenced by inconsistent delay of receiving and transmitting channels, has low requirements on communication rate and channel performance, is not highly dependent on longitudinal channels, and has the advantages of high economical efficiency and high reliability.

Description

technical field [0001] The invention belongs to the technical field of electric 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 on system operation mode changes, and has been widely used in high-voltage transmission lines. However, the correct operation of the longitudinal current differential protection is based on the precise synchronization of the local and opposite currents. [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, complex technology and high cost, which limits the application...

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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