Thunder failure recognition method for row wave protection of DC power transmission line

Abstract

The invention relates to a lightning striking fault identifying method of a direct current power transmitting line traveling wave protection. According to the characteristic difference of voltage traveling wave shape between the formed faults and unformed faults, two-pole voltage traveling wave weight and origin direct current weight are used to identify changing trend of the wave shape; ratio of a initial traveling wave mode maximum value and the second mode maximum value is used for representing saltation that the wave shape is cut; combining the two characteristics to achieve the identification of the voltage traveling wave while not causing the faults by lightning pole tower, lightning striking lightning line, lightning striking line shift central distance and the voltage traveling wave of non-lightning short circuit fault by the lightning pole tower, lightning striking line shift central distance. The interference and identification of the two lightning weaves are combined to improve the identifying reliability. A large number of emulations represent that this method is reliable and effective. The physical conception of this invention is intuitionistic and clear and has a rapid action function. The invention does not be influenced by the fault type and transition resistance and it is easy to achieve and suitable for apllying to direct current system protecting device.

Description

technical field [0001] The invention relates to the technical field of relay protection for electric power systems, in particular to a lightning fault identification method for traveling wave protection of direct current transmission lines. Background technique [0002] With the rapid development of economic construction, long-distance power transmission across regions has become inevitable. Therefore, the ±800kV ultra-high voltage direct current (UHVDC) transmission system has attracted more and more attention. By 2010, my country will build the world's first ±g00kV UHVDC transmission project - Yunguang DC transmission project. Since long-distance power transmission greatly increases the probability of short circuit and lightning strikes, which seriously threatens the stable operation of the DC system, it is necessary to correctly identify lightning wave interference. Lightning impulse is usually a unipolar pulse wave with short rise time and fall time, which belongs to hi...

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Problems solved by technology

However, when lightning strikes the conductor (shielding) on ​​the line and does not cause a fault, the energy ratio of the high-frequency component to the low-frequency component in the traveling wave signal may also be relatively small, which is difficult to distinguish from the situation during the fault

Literature [4] directly judges whether it is lightning interference by comparing the magnitude of the current change before and after the lightning strike or fault, but the threshold value is affected by many factors and is not easy to set, and it does not consider the induced lightning strike

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