Input-current-based method for diagnosing open-circuit fault of diode of subway rectifier set

Abstract

The invention provides an input-current-based method for diagnosing an open-circuit fault of a diode of a subway rectifier set. The method comprises: inputted three-phase alternating currents of fourrectifier bridge grid sides of a rectifier set are collected in real time to obtain three-phase alternating current signals inputted by the four rectifier bridge grid sides; a maximum value of absolute values of all alternating current signals at a current sampling time during the alternating-current power-frequency period is calculated; all sampling current signals during the power-frequency period in which the current sampling time is located are normalized, accumulated summation is carried out, calculation is carried out to obtain a normalized sum value of 12 inputted alternating current signals; and if the normalized sum value of alternating current signals during the continuous five periods exceed a positive threshold Sup or a negative threshold Sdown, occurrence of an open-circuit fault at a diode of a lower bridge arm or upper bridge arm of a corresponding phase of the corresponding rectifier bridge is determined. Therefore, the open-circuit fault of the diode can be detected and the positioning of the fault diode is realized; maintenance is carried out timely and conveniently; and losses increasing and accident occurrence are avoided.

Description

technical field [0001] The invention relates to a method for diagnosing open-circuit faults of diodes of subway rectifier units based on input current Background technique [0002] Most traction rectification substations in my country's urban subway rail transit use the equivalent 24-pulse rectification method to supply DC power to subway vehicles. The reliability and safety of its work directly affect the reliability and safety of subway operation. In the process of operation, the abnormality of the subway rectifier unit can be detected in time and corresponding measures can be taken, which will significantly improve the safe and reliable operation level of the entire system. [0003] In the fault of the subway rectifier unit, there is a better protection scheme for the short-circuit fault of the diode: each rectifier diode is connected in series with a fast fuse. More than twice as large, the fuse blows to protect the diode, and converts a short circuit fault into an ope...

AI Technical Summary

Problems solved by technology

If the open-circuit fault of the diode cannot be detected and taken measures in time, the rectifier circuit still works. This kind of sick work will cause serious distortion of the rectifier waveform, so that the load cannot operate normally, and also increases the harmonic interference to the power grid.

At present, some methods have been proposed for the diode open-circuit fault of the subway rectifier unit, but they can only judge whether the fault has occurred, and cannot locate the faulty diode. The follow-up maintenance only relies on manual search or the experience of maintenance personnel to locate the fault, resulting in a fault It cannot be eliminated quickly and effectively, and the expansion of losses and the occurrence of accidents cannot be avoided in a timely and effective manner, which reduces the efficiency and benefits of subway operation

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