Prediction and Detection Method of Current Transformer Saturation Under Inrush Current

Abstract

There is provided a method for predicting a current transformer saturation, comprising: detecting a first current from a first current transformer at a high voltage side of a transformer and detecting a second current from a second current transformer at a low voltage side of the transformer; calculating a first fundamental vector, a first DC component and a first total RMS of the first current, and calculating a second fundamental vector, a second DC component and a second total RMS of the second current; and generating a prediction signal for the current transformer saturation according to the first fundamental vector, the first DC component, the first total RMS, the second fundamental vector, the second DC component and the second total RMS. The current transformer saturation may be predicted effectively before it triggers a differential protection of the transformer, thus a differential protection mal-operation of the transformer may be avoided.

Description

technical field [0001] The present invention relates to the relay protection of power plants and substation automation systems, and more particularly to a method for predicting and detecting saturation of a current transformer (CT) under surge current. Background technique [0002] In a power system there are often several transformers connected in parallel or in series. If at least one of these transformers is put into operation, there may sometimes be a summing inrush current between these transformers. [0003] Usually, a high-voltage side current transformer and a low-voltage side current transformer are respectively installed on the high-voltage side and low-voltage side of the transformer, and the differential protection of the transformer is realized through these two current transformers. Prolonged inrush current may cause saturation of high-voltage side or low-voltage side current transformers used for transformer differential protection, and then lead to different...

AI Technical Summary

Problems solved by technology

Eventually, when one side of the current transformer is deeply saturated and the other side of the current transformer is working normally, the differential current will be large enough to trigger the transformer differential protection, resulting in differential protection misoperation

[0005] At present, in some substation automation system products, for example, Schneider's Micom P40 platform products, no method is taken to prevent differential protection misoperation

Moreover, users often complain about the misoperation of differential protection.

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