Extra-high-voltage current transformer verification system

Abstract

The invention discloses an extra-high-voltage current transformer verification system. The system comprises an intelligent power frequency power source, a multi-combination reactive power compensator, a multi-combination upflow system, a standard current transformer and a current transformer load bank. According to the invention, by use of a modern power electronic conversion technology according to which a three-phase-to-single-phase power electric electronic power supply and an electrical power supply are connected in series, an adaptive reactive compensation technology and an intelligent detection technology, load parameters of an extra-high-voltage GIS pipeline primary test loop are intelligently and efficiently analyzed, and reactive compensation is carried out automatically according to the load parameters, such that the capacities and the volumes of an onsite power supply and an upflow device are greatly reduced, integration and miniaturization of scattered detection devices are realized, the onsite verification capability and the work efficiency are improved, the cost of manpower and material resources is decreased, and the problem of incapability of detecting an extra-high-voltage current transformer according to detection regulations in a field is solved.

Description

technical field [0001] The invention belongs to the technical field of ultra-high voltage testing, in particular to an ultra-high voltage current transformer calibration system. Background technique [0002] The UHV GIS current transformer has the characteristics of large transformation ratio, long pipeline loop, high integration, and full enclosure. The current transformer cannot be isolated during on-site verification, and a long pipeline busbar and some electrical components need to be brought. The circuit impedance is large. For example, the GIS current transformer test circuit in Lanzhou East UHV Substation is as long as 390 meters. In this way, the test power supply and current-raising equipment capacity required for on-site verification of UHV GIS current transformers with large transformation ratio and long primary circuit Huge, for example, a 4000A / 1A UHV current transformer in a 200-meter GIS circuit requires a power supply capacity of about 800kVA at 120% of the r...

AI Technical Summary

Problems solved by technology

These two indirect test methods avoid the problem of excessive requirements on the capacity of the current booster, voltage regulator and on-site power supply, and greatly reduce the volume and weight of the equipment carried in the on-site test. However, the indirect test methods cannot meet the requirements of "JJG1021- 2007 "Power Transformer" verification regulations, the real error of the current transformer under the condition of large current cannot be obtained, which reduces the reliability and authenticity of the test data

According to the statistical results of on-site verification of UHV current transformers, there are many cases where the upper limit error of current transformers is out of tolerance, especially near the rated current range. As the test current increases, the error increases. The reason for this phenomenon may be It is because the coil material of the current transformer is vibrated during installation and transportation, which causes the relative magnetic permeability of the iron core to decrease, and the saturation of the magnetic circuit near the rated current causes a sharp change in the error, so the small current extrapolation method cannot find this phenomenon, resulting in The verification data is not true and reliable; there are many problems in the calculation method of small voltage measurement. First, although the principles of current transformers are similar, but for the same type of current transformers to be verified, the ideal mathematical model and the actual current transformer It is difficult to determine the degree of equivalence between them. Although it can be verified by comparison and verification through simulation and a large number of experiments, the workload is undoubtedly huge; secondly, even if a mathematical model of a type of current transformer is obtained, However, the iron core materials, winding methods, installation methods, and compensation methods used by various current transformer manufacturers in the product design and production process are all different, and it is difficult to establish a unified mathematical model. The measurement results are often difficult to reflect the real error data, especially for the current transformer with compensation, there is no way to measure its error; third, to obtain an accurate mathematical model, it is necessary to accurately measure the electrical parameters of the current transformer, For the small voltage method, the measured voltage and current are extremely small, and it is difficult to accurately measure the electrical parameters. Moreover, when performing on-site verification of current transformers, there are often strong interferences on site. It is even more difficult to measure under this working condition. Accurate electrical parameters are measured, and therefore it is difficult to obtain an accurate mathematical model, so the error data obtained by using the small voltage method measurement calculation method is difficult to reflect the real error data of the current transformer

The above two indirect methods not only cannot effectively verify the transformer, but also may misjudge, so it is particularly important to verify the error of the UHV current transformer at each measurement point in accordance with the requirements of the "JJG1021-2007 Power Transformer" verification regulations

[0004] In view of the limitation of on-site verification conditions and the complexity of operation of current transformers in UHV GIS, the above-mentioned traditional current booster method and indirect test method cannot meet the requirements of on-site verification.

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