Circuit current differential protection method preventing abnormal large number of combination unit

Abstract

The invention provides a circuit current differential protection method preventing an abnormal large number of a combination unit. Firstly, the point with the maximum amplitude is selected by comparing cycle current sampling values on the two sides of a circuit, if the point is larger than an abnormal threshold, the differential motion does not act, if the point is not larger than the abnormal threshold, and the point with the second largest amplitude is selected on the same side with the maximum point; secondly, the current sampling value at the maximum point position and the current sampling value at the second largest point position are respectively modified according to logic, and complete cycle Fourier transform is carried out to obtain current phase magnitudes at the two ends; lastly, current differential protection judgment is constructed to achieve failure judgment. According to the circuit current differential protection method, the differential protection false action caused by the abnormal large number of the combination unit of an intelligent substation can be effectively prevented by processing the large number of the sampling values, and the circuit protection reliability is improved.

Description

technical field [0001] The invention belongs to the field of relay protection of power systems, and in particular relates to a line current differential protection method for preventing an abnormally large number of merging units. Background technique [0002] Line current differential protection has high reliability, sensitivity and simple structure, and is the most widely used main protection principle for transmission lines at present. With the construction of digital / intelligent substations, the electrical quantity collected by the protection device is imported from the conventional secondary cable, and then it is collected and transformed by the merging unit and then imported through the optical fiber. However, when the merging unit itself works abnormally due to software defects, electromagnetic interference, overheating damage, etc., the output current sampling value may be distorted and amplified, resulting in differential protection malfunction and seriously threate...

AI Technical Summary

Problems solved by technology

However, when the merging unit itself works abnormally due to software defects, electromagnetic interference, overheating damage, etc., the output current sampling value may be distorted and enlarged, resulting in differential protection malfunction and seriously threatening the safety of the power grid.

This phenomenon has occurred several times in the dynamic model laboratory and the field, but the current research in this area is still blank

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