An Online Monitoring Method of CVT Capacitance Based on Zero Sequence Voltage Monitoring

Abstract

The invention discloses a CVT capacitance on-line monitoring method based on zero sequence voltage monitoring. The method comprises the steps of: S10, parallelly reading the zero sequence voltage of at least one CVT by a plant station monitoring system, wherein the zero sequence voltage is normal if only deviating from normal values; S20, querying each CVT for detecting whether each zero sequence voltage exceeds a first voltage threshold, and for one CVT, if the zero sequence voltage thereof is larger than or equal to the first voltage threshold, entering a step S30; and S30, counting the abnormity duration time of zero sequence voltage of the CVT, judging whether the zero sequence voltage of the CVT exceeds a second voltage threshold, if the zero sequence voltage is smaller than the second voltage threshold and the duration time is larger than a first set time, then determining that the capacitance of the CVT is broken down. The operation condition of the CVT capacitance is accurately judged by the utilization of the zero sequence voltage of the CVT, deep processing is carried out by the utilization data of the plant station monitoring system, no equipment needs to be added, and the reliability is improved.

Description

technical field [0001] The invention relates to the technical field of electric power online detection, in particular to an online monitoring method of CVT capacitance based on zero-sequence voltage monitoring. Background technique [0002] If you want to find out whether the capacitance of the CVT breaks down, you generally need to rely on the ratio error test. However, it is more difficult to carry out CVT ratio error testing at this stage: 1. Corresponding qualifications are required. The state controls the ratio error testing more strictly. Generally, only one unit in a province is qualified to carry out this test, and its work schedule is relatively full. , it is difficult to arrange the construction period; 2. The test equipment is relatively large, and the test is time-consuming and laborious, resulting in a higher price. [0003] The existing pre-test inspection cannot find the capacitive breakdown defect of the capacitive voltage transformer (CVT in English abbrevi...

AI Technical Summary

Problems solved by technology

However, it is more difficult to carry out CVT ratio error testing at this stage: 1. Corresponding qualifications are required. The state controls the ratio error testing more strictly. Generally, only one unit in a province is qualified to carry out this test, and its work schedule is relatively full. , it is difficult to arrange the construction period; 2. The test equipment is relatively large, and the test is time-consuming and laborious, resulting in a higher price

[0003] The existing pre-test inspection cannot find the capacitive breakdown defect of the capacitive voltage transformer (CVT in English abbreviation): the current pre-test procedure has no requirements for the ratio error and angle difference test, and theoretically, the CVT ratio error is generally determined by the capacitor The pre-test procedure has test requirements for capacitance and dielectric loss, but its accuracy requirements are low and cannot meet the test requirements for transformation ratio errors

[0004] Part of the busbar CVT has not been tested for the ratio error, and the defect of capacitor breakdown cannot be found

According to the "National Measurement and Verification Regulations of the People's Republic of China - Power Transformer", the reference error of the voltage transformer is measured every four years, and the bus CVT is not connected to the metering device, so the standard has no binding force on the bus CVT, so the bus CVT did not carry out the error test project before, and the phenomenon of capacitor breakdown could not be found

[0005] However, existing CVT online monitoring devices, such as the "CVT online monitoring system" with application number 201110003819. Accuracy, the requirement is not high, resulting in the failure to find hidden dangers such as capacitor breakdown, and the breakdown of the capacitor will cause the CVT ratio error to fail, resulting in measurement data errors

[0006] Therefore, the existing on-line monitoring device and the power failure pre-test and fixed inspection cannot find the defect of CVT capacitor breakdown. Generally, the hidden danger of CVT capacitor breakdown can only be found by relying on the ratio error test.

However, due to the large capacitance of the CVT, the ratio error test has higher requirements on the capacity of the instrument, and it is more difficult to carry out the ratio error test.

Images