Method and system for avoiding same-tower multi-loop vertical connection zero sequence direction protection maloperation

Abstract

The present invention provides a method and a system for avoiding same-tower multi-loop vertical connection zero sequence direction protection maloperation. The method and the system are based on station domain information, it is determined whether there is a loop with faults or not through determination of whether a first criterion is established, it is determined whether loops except the fault loops in the multiple loops with voltage levels having faults have zero sequence voltage zero-crossing points or not according to a second criterion, and when loops except the fault loops in the multiple loops with voltage levels having faults have zero sequence voltage zero-crossing points, the reverse compensation is performed; it is determined whether loops with voltage levels without faults have zero sequence voltage zero-crossing points or not according to a third criterion in a same-tower mixed voltage multiple loops, and if yes, the vertical connection zero sequence protection is closed.The method and the system completely solve the problems of the same-voltage and mixed voltage multi-loop vertical connection zero sequence direction protection maloperation of the same tower caused by open-phase operation or break line faults and ensure the precision of the vertical connection zero sequence direction protection so as to improve the electric system maloperation capacity and the power grid safe and stable operation level.

Description

technical field [0001] The present invention relates to the field of electric power protection, and more specifically, relates to a method and system for preventing maloperation of longitudinal zero-sequence direction protection of multi-circuit lines on the same tower. Background technique [0002] The multi-circuit line on the same tower has the characteristics of less number of towers, small area of ​​transmission corridor, strong transmission capacity, and large path width. It can avoid redundant projects that must be implemented when passing through mountains and cities. Back-to-back transmission lines have significant economic advantages while also meeting the requirements for high-capacity transmission. In multi-circuit lines on the same tower, the application of longitudinal zero-sequence directional protection is quite extensive and the technology is mature. In the prior art, the longitudinal zero-sequence protection should not be affected by the magnitude of the z...

AI Technical Summary

Problems solved by technology

[0003] In multi-circuit lines with the same tower and same pressure, after a non-full-phase operation or disconnection fault occurs in the first circuit, the busbars on both sides of the transmission line will have zero-sequence voltages with opposite phases. voltage compensation, it will cause malfunction of the healthy line

At the same time, the load transfer caused by non-full-phase operation or disconnection fault is likely to cause overload of other lines, and there is also the possibility of malfunction

For the mixed-voltage line on the same tower, due to the mutual inductance between the loops, the other loop will have a zero-sequence electrical quantity distribution that is exactly the same as the broken line, resulting in misoperation

At present, there is no complete solution to the problem of misoperation of longitudinal zero-sequence direction protection caused by non-full-phase operation or disconnection fault, and it does not meet the technical standards

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