Device and method for synchronous measurement of short-circuit current distribution in substations

Abstract

The invention discloses a synchronous measurement device of short-circuit current distribution in a transformer substation. The synchronous measurement device of the short-circuit current distribution in the transformer substation comprises a plurality of oscilloscopes, wherein an external trigger signal of an oscilloscope serves as trigger source of other oscilloscopes, the other oscilloscopes and the oscilloscope are in parallel connections respectively through coaxial cables to achieve synchronous trigger of all oscilloscopes; the oscilloscope is connected with a current transformer, total fault current can be measured by the current transformer when a short-circuit ground fault occurs; the other oscilloscopes all correspond to and connect with the current transformers, and ground current and transformer neutral point current can be measured by the corresponding current transformers when the short-circuit ground fault occurs. The device is used for synchronously measuring the short-circuit current distribution in the transformer substation when the short-circuit ground fault occurs. The invention simultaneously discloses a synchronous measurement method of the short-circuit current distribution in the transformer substation.

Description

technical field [0001] The invention relates to the field of high-voltage substation measurement, in particular to a device and method for synchronously measuring short-circuit current distribution in a substation. Background technique [0002] When a short-circuit ground fault occurs in a substation, the total fault current can be divided into the ground current part, the ground wire shunt part and the transformer neutral point return part. The total fault current, ground current, ground wire shunt and transformer neutral point return, the magnitude of these four currents is called the distribution of short-circuit current, referred to as short-circuit current distribution, and as long as the magnitude of three of them is obtained, it is easy to The size of the fourth quantity can be obtained by Kirchhoff's law. [0003] The size of the ground current directly affects the equipment and personal safety in the station. This part of the current will generate ground potential...

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Problems solved by technology

However, there are the following disadvantages: there is no uniform time standard among the measured quantities, the triggering time of the oscilloscope is not uniform, and the initial recording time of each waveform is inconsistent. The measurement results obtained in this way can generally only be compared with the amplitude or effective value, and cannot be used in Compare the waveforms on the same time axis; when using the current measured in this way to calculate the value of the ground current, you can only use the effective value or amplitude of each current to add or subtract, and the result has a large error

However, the above method has the following disadvantages: each grounding point is not connected to the ground grid at the same point, but distributed throughout the ground grid, so for the current distribution, the ground grid is not just a concentrated impedance, the model of this method is equivalent to There is an error; the magnetic field generated by the phase current of the line will generate an induced voltage on the ground wire, which will affect the shunt capacity of the ground wire. The method of equating the ground wire to a concentrated shunt impedance ignores the influence of the phase wire and will generate errors; these models Equivalence will introduce a lot of errors, which will affect the accuracy of the results. Compared with the actual measurement on site, its disadvantages are obvious

However, the existing on-site measurement methods basically ignore the importance of synchronous measurement, and synchronous measurement of current distribution is an important guarantee for the accuracy of measurement results

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