On-line detection method for secondary circuit disconnection of transformer used in conventional sampling instrument in substation

Abstract

A method for detecting disconnection of a transformer secondary circuit for a conventional sampling instrument in a substation, comprising the steps of: S1, adding a mega-level pull-up resistor R1 and a pull-down resistor R2 with unequal resistance values ​​to the secondary circuit of the instrument transformer, the resistance value The ratio is 1:2; for the current type PT transformer, a resistor R0_1 is connected in series on the source side, and a resistor R0_2 is connected in parallel at the secondary side; for the voltage type CT transformer, a resistor R0 is connected in parallel at the source side; S2, identify the fault and Processing: When the continuous 1 / 4 cycle time of the AD sampling value is near the offset potential of the secondary circuit disconnection, it is judged that the secondary circuit is disconnected; the sampling device performs disconnection exception processing: the quality setting of the sampling value output by the merging unit SV is abnormal , and drive GOOSE to release the abnormal alarm point of the sampling value; the conventional sampling protection device blocks the relevant protection of the disconnection channel, and the sampling value of the disconnection channel of the conventional sampling measurement and control device is invalidated, and an alarm is issued. The invention can realize the self-inspection of the secondary circuit state of the conventional sampling device in the substation, and improve the reliability of the conventional sampling device in the substation.

Description

technical field [0001] The invention discloses a method for detecting disconnection of a secondary circuit of a transformer, in particular to an online detection method for a disconnection of a secondary circuit of a transformer used for a conventional sampling instrument in a substation. Background technique [0002] The substation is an indispensable and important link in the power system. It is responsible for the heavy task of power conversion and power redistribution, and plays a decisive role in the safety and economic operation of the power grid. Instrument transformers are used to collect voltage and current data of substations, and are widely used in merging units or conventional protection, measurement and control. [0003] The requirement of on-site digital output of the merging unit makes the merging unit need to withstand the test of harsh electromagnetic environment, temperature and humidity on site. In this way, the reliability of the merging unit is very imp...

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Problems solved by technology

[0005] However, in the prior art, no method has been found to detect the disconnection of the secondary circuit of the instrument transformer of the acquisition device in the routine sampling of the substation. However, such faults frequently occur on site, and the identification of this fault should be used as a necessary part of the self-check of the device status.

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