Analog input type merging unit protection current transformer disconnection detection method

Abstract

The invention discloses an analog input type merging unit protection current transformer disconnection detection method, and the method comprises the steps: judging that a protection current transformer in a merging unit is not disconnected if there is a protection current or not no matter whether there is a measurement current or not; if the protection current does not exist and the measurement current does not exist, judging that the protection current transformer in the merging unit is not broken; and if the protection current has no current and the measurement current has current, judging that the protection current transformer in the merging unit is disconnected. Under the condition that hardware of an existing analog input type merging unit is not changed, no-current / current judgment is carried out on protection current and measurement current sampling values connected into the merging unit, and therefore whether the internal protection current transformer is disconnected or not is rapidly judged; if the internal protection current transformer is disconnected, the corresponding protection current data quality in the merging unit sampling value message can be rapidly set to be invalid, an alarm is sent out, a transformer substation relay protection device is prevented from using abnormal sampling data for protection calculation, and the maloperation risk is reduced.

Description

technical field [0001] The invention relates to a method for detecting disconnection of a current transformer protected by an analog quantity input merging unit, and belongs to the technical field of intelligent automatic safety control of substations. Background technique [0002] Due to frequent problems in the application process of electronic transformers, the reliability has not been fully recognized. Since 2011, analog input merging units have gradually replaced digital input merging units and become the mainstream equipment for digital sampling in domestic smart substations. . [0003] The analog input merging unit receives the current and voltage signals from the primary transformer through the internal transformer, converts them into small voltage signals and inputs them to the A / D chip, and finally outputs digital signals to the relay protection device. A / D chips currently on the market will output a DC component when the protection current transformer is disconne...

AI Technical Summary

Problems solved by technology

However, this method itself cannot detect the equipment failure state of the disconnection of the internal protection current transformer of the merging unit, and the relay protection device will still use the abnormal data after the disconnection to perform protection calculations, so there is a certain probability that the protection device will malfunction

[0005] On the other hand, because the analog input merging unit is widely used in my country's smart substations, the cost of hardware improvement for the equipment is huge

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