A method for judging the wrong phase sequence of the AC incoming line of the converter bridge

Abstract

The invention discloses a method for judging phase sequence misconnection of an AC incoming wire of a converter bridge. When an ice melting device is subjected to a no-load pressure test and when trigger pulse of the converter bridge is unlocked, the DC voltage of the converter bridge has larger phase step and causes tripping of a voltage protection action of the no-load pressure test; and in addition, in a period of time after the trigger pulse of the converter bridge is unlocked, the peak value of the absolute value of the DC voltage of the converter bridge is larger than a constant voltage value, and the phase sequence misconnection fault of the AC incoming wire of the converter bridge is judged through a certain signal anti-shaking time-delay. The method disclosed by the invention can be used for effectively judging the phase sequence misconnection fault of the AC incoming wire of the converter bridge; and a protection system can be used for automatically determining the reason of fault after the protection action of the no-load pressure test according to the method and gives a fault analysis prompt.

Description

technical field [0001] The invention relates to a relay protection technology, in particular to a method for judging that the phase sequence of an AC incoming line of a converter bridge is wrongly connected. Background technique [0002] Icing of transmission lines in winter seriously threatens the safe operation of the power system. The successful development of the DC ice melting device has played a huge role in improving the ability of the power grid to resist ice disasters. The basic principle of the DC ice-melting device is to use the converter bridge to convert the AC current into a DC current, inject it into the AC wire, and use the DC current to generate heat in the wire resistance to melt the ice. [0003] Open Line Tests (OLT), also known as no-load pressurization test, is a very important test in DC ice melting device and HVDC transmission engineering system test. The method of the OLT test is to disconnect the load circuit of the rectifier, and gradually increas...

AI Technical Summary

Problems solved by technology

During the OLT test, the wrong phase sequence of the AC incoming line will lead to the OLT-related voltage protection action, and the OLT test will be terminated.

However, there are many fault causes for OLT-related protection actions, and technicians need to manually analyze the fault recording files of the control and protection system of the DC deicing device to determine the cause of the fault. This fault analysis process will take a lot of time and is subject to personal technical level. Affected by factors such as field experience and on-site experience, technicians may not be able to locate the cause of equipment failure in a timely and accurate manner

At present, there is no method for clearly and effectively judging the phase sequence fault of the three-phase AC incoming line of the converter bridge.

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