Method and system for evaluating direct current magnetic bias influences of transformers

Abstract

The invention provides a method and system for evaluating direct current magnetic bias influences of transformers. The method comprises the steps that the magnetic bias influence probability of metrostray current on pre-divided transformer substations in a power grid is calculated; the risk degree of each transformer substation influenced by the direct current magnetic bias is calculated; based on magnetic bias monitoring data and the risk degree of each transformer substation influenced by the direct current magnetic bias, direct current influence factors of a neutral point of each transformer are calculated; according to the risk degree of the magnetic bias influence of a non-monitoring site and the direct current influence factors of the neutral point of each transformer, the direct current of the neutral point of the non-monitoring site is calculated; based on an association rule of the monitoring data, the direct current level of a neutral point of a monitoring site is evaluated;based on the direct current evaluation level of the neutral points of the non-monitoring site and monitoring site, the magnetic bias warning grade of each site is divided, and a site range involved in the magnetic bias influence is delimited. The method and system for evaluating the direct current magnetic bias influence of the transformers have the advantages that equipment hazards can be timelyfound and quickly removed, and the management ability and application response ability of the magnetic bias influence are improved.

Description

technical field [0001] The invention belongs to the field of AC / DC hybrid power transmission, and in particular relates to a method and system for evaluating the influence of transformer DC bias. Background technique [0002] The power supply traction network of some existing urban subways usually adopts rail as one pole of power supply. It is impossible to completely insulate the subway rails from the earth, so when the subway train starts and runs, some stray currents will leak to the ground through the rails, causing changes in the distribution of ground potential around the rails. When the distance between the subway and the surrounding AC power stations is relatively close, the change of the ground potential distribution may cause a DC component at the neutral point of the main transformer of the urban power grid that exceeds the upper limit of the DC bearing capacity of the transformer, causing problems such as DC bias of the transformer. [0003] Subway rails are gen...

AI Technical Summary

Problems solved by technology

When the distance between the subway and the surrounding AC power stations is relatively close, the change of the ground potential distribution may cause a DC component at the neutral point of the main transformer of the urban power grid that exceeds the upper limit of the DC bearing capacity of the transformer, causing problems such as DC bias of the transformer

[0003] Subway rails are generally laid underground with a large geographical span. Subway stray currents are affected by factors such as rail resistivity, transition resistance, locomotive traction current, length of power supply section, locomotive operation mode, and underground railway layout. The amplitude and direction of the variable bias magnetic current will change with the change of the position and operation mode of the subway locomotive, which has great randomness, and it is difficult to accurately judge and evaluate through simulation calculations and other means

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