Monitoring method for short-circuit fault between stator core and through-hole screw of synchronous generator

Abstract

The invention discloses a method for monitoring a short-circuit fault between a stator core and a cross-core threaded rod in a synchronous generator. A high-resistance resistor and a sampling resistor are connected with the ground, wherein the high-resistance resistor and the sampling resistor are in series connection and connected to the cross-core threaded rod which is arranged in the stator core in the synchronous generator; a momentary value of voltage across two ends of the sampling resistor are collected online, the momentary value of the voltage is compared with a fault determining threshold value, and when the momentary value of the voltage exceeds the fault determining threshold value, it is determined that the short-circuit fault occurs between the stator core and the cross-core threaded rod in the synchronous generator. The method can solve the deficiency in the prior art and improve the diagnostic ability of such faults.

Description

technical field [0001] The invention relates to the technical field of generators, in particular to a monitoring method for a short-circuit fault between a stator iron core and a through-hole screw of a synchronous generator. Background technique [0002] The stator core of the synchronous generator is made of silicon steel punched sheets stacked together. In order to prevent the core punched sheets from shifting and vibrating during operation and cutting the insulation of the stator winding, it is necessary to apply axial pressure to the core punched sheets with the help of a through-core screw to make the core punched sheets fasten. In order to prevent overheating damage caused by local eddy current or circulating current caused by the short circuit of the iron core punching sheet, an insulating material is set between the core screw and the punching sheet, see figure 1 . [0003] In order to avoid the short circuit of the core screw through the pressure ring and other s...

AI Technical Summary

Problems solved by technology

This method has been widely adopted by the international electric power industry. However, this method also has obvious disadvantages, that is, it can only find the short-circuit fault of the stator tooth slot, and cannot respond sensitively to the short-circuit fault between the through-hole screw and the stator core.

[0007] To sum up, currently there are only detection methods for diagnosing the insulation state of the core screw and the short-circuit fault of the stator core, and they are all offline detection methods, which cannot detect the fault in time and may lead to the deterioration of the fault

Among them, neither the iron loss test method nor the ELCID method can find the short-circuit fault between the through-hole screw and the stator core located deep in the stator core, and the short-circuit fault between the through-hole screw and the stator core is precisely the one with the highest occurrence rate and the most destructive Therefore, it is necessary to develop an online, high-sensitivity detection method for the short-circuit fault between the core screw and the stator core.

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