Fault monitoring method for secondary circuit of metering current transformer

Abstract

The invention provides a fault monitoring method for a secondary circuit of a metering current transformer. The method includes the steps that 1, a high-frequency voltage signal Uh is injected into the secondary circuit of the monitored metering current transformer; 2, a current signal I2 in the secondary circuit is measured and divided into a power frequency current signal Ip and a high frequency current signal Ih; 3, AD conversion is carried out on the Ip and the Ih; 4, the ratio I gamma of the positive amplitude value and the negative amplitude value of the Ip within a power frequency current period is calculated; 5, the admittance Yh of the secondary circuit is calculated and is equal to Ih/Uh; 6, the electric energy value Ec is calculated according to the Ip and the power factor cos phi and the power frequency voltage Up of an electric energy meter of the secondary circuit of the monitored current transformer; 7, the difference value delta E within the time interval T is calculated and is equal to the difference between the Ec and Em; 8, the fault type of the secondary circuit of the monitored current transformer is judged according to the ratio I gamma, the difference value delta E and the admittance value Yh. The method is simple and reliable, faults of the secondary circuit of the monitored current transformer are monitored in real time and online, and the fault position and fault type of the circuit are judged and recognized.

Description

Technical field: [0001] The invention relates to an online monitoring method, in particular to a secondary circuit fault monitoring method of a current transformer for metering. Background technique: [0002] Current transformer is an important component of power system operation and electric energy metering. It is a contact element between the primary system and the secondary system in the AC circuit, and is used to transmit information to measuring instruments, protection and control devices, etc. [0003] The faults that may occur in the secondary circuit during the operation of the current transformer include: poor contact contact, contact damage, artificial short circuit or disconnection, transformer damage, etc. These faults can be attributed to the secondary circuit open circuit or Short circuit; the failure of the secondary circuit of the current transformer will directly affect the accuracy of electric energy measurement, and even lead to electric safety accidents. ...

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Problems solved by technology

Since these two detection methods require inspectors to go to the site for detection work, and sometimes require pow

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