A method for on-line identification of out-of-tolerance voltage transformer

Abstract

The invention provides an out-of-tolerance online identification method for voltage transformers. On the basis of converting the secondary measurement output values ​​of multiple VTs in a substation into monitoring statistics, the mapping relationship between monitoring statistics and each VT error variation is established. . The difference between the error value of the VT first inspection report and the specified error limit of VT file information is used as the error change limit for judging the VT error state, and then the mapping relationship is used to convert the error change limit into a monitoring statistic, and each VT is used for monitoring The contribution rate of the statistic defines multiple control limits, and the VT exceeding the limit is regarded as suspected out-of-tolerance. For the VT suspected to be out-of-tolerance, it is further determined whether it is out-of-tolerance. The application of the present invention can make the detection of out-of-tolerance VT in the long-term operation process get rid of the double dependence on planned power outages and physical standards, help to find out-of-tolerance VT in time, guide the operation and maintenance work of power companies, and promote the accuracy of power transmission and transformation equipment Maintenance, to provide protection for the fairness of electricity trade and the safe operation of the power grid.

Description

technical field [0001] The invention relates to the field of state evaluation and fault diagnosis of power distribution equipment, and more specifically, to an out-of-tolerance online identification method of a voltage transformer. Background technique [0002] A potential transformer (VT) is a general-purpose device that converts high voltages to low voltages for measurement. In the long-term operation process, the measurement error of VT may deteriorate until it exceeds the specified limit of file information error, resulting in the occurrence of out-of-tolerance faults. The out-of-tolerance will lead to the deviation of the electric energy calculated by the voltage and current data, which may cause a huge amount of electric energy trade disputes. At the same time, it may also cause improper intervention and abnormal operation of the grid automation system, which may lead to instability and cracking of the power system. Therefore, it is very important to find and replace ...

AI Technical Summary

Problems solved by technology

But at present, this method can only judge whether the VT error changes or not, and cannot judge whether the VT exceeds the allowable error range. The reasons are as follows: 1. This method cannot obtain the absolute value of the error

Since only the measured value of VT is used for evaluation, the initial value of the error is unknown, and the relative change of the error state can only be judged from the change of the statistics, but the absolute value of the error cannot be obtained, so it is impossible to judge whether the abnormal change of the error exceeds the allowable value margin of error

2. It is impossible to judge the magnitude of the change in error

The current method is to convert the measurement data into monitoring statistics, and judge whether there is an error change based on the changes in the monitoring statistics of the modeling data and the monitoring data. The quantitative relationship between the monitoring statistics and the error change has not been established. Determine whether the error has changed, so the size of the error change cannot be obtained

In summary, the above method cannot evaluate the error value, so it does not have the ability to identify out-of-tolerance VT, and cannot guide the formulation of maintenance plans

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