Insulation installation and grounding protection method for rectifier transformer

Abstract

The invention discloses an insulation installation and grounding protection method for a rectifier transformer. An insulation pad, a grounding cable, a current transformer and a protection measurementand control unit are included. The rectifier transformer body is positioned on the insulation pad; one end of the grounding cable is connected to a grounding terminal of the rectifier transformer body; the grounding cable penetrates through the current transformer, the other end of the grounding cable is connected to a grounding busbar of a substation, a secondary terminal of the current transformer is connected with the protection measurement and control unit, and the protection measurement and control unit is connected with a medium-voltage cabinet protection tripping circuit through a control cable. According to the invention, the grounding fault of the secondary side of the rectifier transformer can be discovered timely and isolated quickly, and the problem that the grounding fault ofthe secondary side of the rectifier transformer is difficult to discover is solved thoroughly; the current setting value of grounding protection can be set to be very small, the sensitivity is very high, and the method is completely independent of other protection and is simple and reliable.

Description

technical field [0001] The invention belongs to the technical field of urban rail transit, and in particular relates to a rectifier transformer insulation installation and grounding protection method. Background technique [0002] Urban rail transit mainly adopts the DC power supply system, and rectifier transformers play an extremely important role as heavy-duty, high-power power conversion equipment. In domestic urban rail transit projects, the rectifier transformer is usually installed without insulation, and the rectifier transformer body is directly connected to the ground busbar of the substation through a cable or copper braid. When a single-phase ground short circuit occurs on the secondary side of the rectifier transformer, the ground potential of the traction substation is raised, the rail potential limiting device is closed, and the negative pole is short-circuited to the ground, the short circuit path of the secondary side of the rectifier transformer is connecte...

AI Technical Summary

Problems solved by technology

However, this method relies heavily on the rail potential limiting device, which requires the rail potential limiting device to be reliable enough

[0003] If the rail potential limiting device cannot be closed in time due to failure or other reasons, the ground fault current will be greatly reduced at this time, mainly depending on the insulation resistance between the rail and the ground, and the ground fault current is difficult to distinguish from the normal load current. Because the rectifier transformer is not insulated and installed, the grounding current cannot be measured, so the high-voltage side protection device cannot achieve over-current protection or zero-sequence protection

If the fault is not found and cleared in time, it will lead to increased line loss, increased stray current, burnt out of the weak current equipment in the substation, and may even lead to electrical fires in severe cases, resulting in major personal equipment safety accidents

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