冲击电压下油纸绝缘油中电场测量技术研究
发布时间：2019-06-19 10:52
【摘要】：电力变压器是电力系统的核心,其绝缘设计是重中之重。冲击电压下油纸绝缘结构的电场分布特性是变压器绝缘设计的关键环节,能够准确测得在冲击电压下变压器油纸绝缘油中电场及其随温度、水分的变化特性,对于改善其绝缘设计,提升变压器绝缘强度及电网过电压水平有着重大意义。冲击电压是单极性脉冲电压,容易产生大量的空间电荷,而目前大多数变压器冲击电场的计算均为利用仿真软件基于容性场等效进行,无法考虑空间电荷对电场所造成的影响,只能根据理论计算结果结合许用场强选择合理的裕度作为设计值。但仿真结果缺乏实际测量的支撑与验证,冲击电压下的电场特性尚不明朗。针对目前冲击电压下油纸绝缘油中电场测量仍然存在测量灵敏度和准确度较低的问题,本文基于Kerr效应原理,提出了冲击电压下油纸绝缘油中电场非接触式的实际测量方法,研制了一套由光路系统、光电转换器件、有机玻璃密封腔体、冲击电压源、温度水分循环控制系统构成的油纸绝缘空间电场测量装置,为后续油纸绝缘油中电场测量奠定了基础。针对电场测量准确性问题,从准确性受到的诸多客观因素方面从发,分析了固有噪声、温度、电场计算方法、附加相位差及角度调节精度等多个方面对测量结果准确性的影响,并对影响较大的误差来源提出相应的抑制方法。利用黄铜平板电极在均匀电场下对装置性能进行了标定和检验,研究结果表明:在低电压下的电场测量值与电场实际值在波形变化及数值上取得了很好的一致性,装置最小可测峰值为3.49k V/mm的雷电冲击电场,最大误差仅为3.56%,解决了测量灵敏度和准确度较低的问题。开展了温度和水分对冲击电压作用下油中电场的影响研究。研究结果表明:在60k V的标准雷电冲击电压下,随着温度的上升,油中电场总体呈下降趋势,在波峰处下幅程度最大,25℃时下幅已达9.2%,60℃时下幅程度最大,峰值处下降41.6%;在100k V的标准雷电冲击电压下,水分含量较低时,油中电场与外施电场差别不大,随着油中水分含量的上升,油中电场总体呈下降趋势,在波峰处尤为明显,最大下降幅度达到20.5%。试验结果定性分析如下:随着油中温度的上升,油电阻率下降,根据已有的参考文献可得,油中由阳极板发射的正离子迁移速率加快,在很短的时间内越过了电场测量点,从而削弱了空间电场;由于水是强极性分子,极化效应明显,随着油中水分的增加,单位体积内水分子数目随之增加,极化效应对外施电场的削弱也越来越明显。
[Abstract]:Power transformer is the core of power system, and its insulation design is the most important. The electric field distribution characteristic of the insulation structure of the oil paper under the impact voltage is the key part of the transformer insulation design, can accurately measure the electric field in the oil paper insulating oil of the transformer under the impact voltage and the change characteristics of the temperature and the moisture, It is of great significance to improve the insulation strength of the transformer and the over-voltage level of the power grid. The impact voltage is a unipolar pulse voltage, which is easy to generate a large amount of space charge, and the current calculation of the impact electric field of most of the transformers is based on the equivalent of the capacitive field by the simulation software, and the influence of space charge on the electric field cannot be taken into account, The reasonable margin can only be selected as the design value according to the theoretical calculation result and the allowable field strength. However, the simulation results lack the support and verification of the actual measurement, and the electric field characteristics under the impact voltage are not yet clear. Aiming at the problem that the measurement sensitivity and the accuracy of the electric field measurement in the oil-paper insulating oil under the current impact voltage still exist, the practical measuring method of the electric field non-contact in the oil-paper insulating oil under the impact voltage is put forward based on the Kerr effect principle, and a set of electric field non-contact electric field measurement in the oil-paper insulating oil under the impact voltage is developed, A photoelectric conversion device, an organic glass sealing cavity, an impact voltage source and a temperature water circulation control system, wherein the electric field measuring device is used for laying a foundation for the electric field measurement in the subsequent oil paper insulating oil. In view of the accuracy of the electric field measurement, the influence of the inherent noise, temperature, the calculation method of electric field, the additional phase difference and the angle adjustment precision on the accuracy of the measurement results is analyzed from many objective factors of the accuracy. And a corresponding suppression method is proposed for the source of the error with the larger influence. The performance of the device is calibrated and tested under a uniform electric field with a brass plate electrode. The results show that the electric field measurement at low voltage and the actual value of the electric field have good agreement with the change of the waveform and the numerical value. The minimum measurable peak of the device is 3.49k V/ mm. The maximum error is only 3.56%, and the problem of low measurement sensitivity and accuracy is solved. The effect of temperature and water on the electric field in oil under the action of impact voltage is studied. The results show that under the standard lightning impulse voltage of 60k V, with the increase of the temperature, the electric field in the oil has a downward trend, the lower amplitude at the peak is up to 9.2%, the lower amplitude is the largest at the time of 60 鈩，
本文编号：2502291
[Abstract]:Power transformer is the core of power system, and its insulation design is the most important. The electric field distribution characteristic of the insulation structure of the oil paper under the impact voltage is the key part of the transformer insulation design, can accurately measure the electric field in the oil paper insulating oil of the transformer under the impact voltage and the change characteristics of the temperature and the moisture, It is of great significance to improve the insulation strength of the transformer and the over-voltage level of the power grid. The impact voltage is a unipolar pulse voltage, which is easy to generate a large amount of space charge, and the current calculation of the impact electric field of most of the transformers is based on the equivalent of the capacitive field by the simulation software, and the influence of space charge on the electric field cannot be taken into account, The reasonable margin can only be selected as the design value according to the theoretical calculation result and the allowable field strength. However, the simulation results lack the support and verification of the actual measurement, and the electric field characteristics under the impact voltage are not yet clear. Aiming at the problem that the measurement sensitivity and the accuracy of the electric field measurement in the oil-paper insulating oil under the current impact voltage still exist, the practical measuring method of the electric field non-contact in the oil-paper insulating oil under the impact voltage is put forward based on the Kerr effect principle, and a set of electric field non-contact electric field measurement in the oil-paper insulating oil under the impact voltage is developed, A photoelectric conversion device, an organic glass sealing cavity, an impact voltage source and a temperature water circulation control system, wherein the electric field measuring device is used for laying a foundation for the electric field measurement in the subsequent oil paper insulating oil. In view of the accuracy of the electric field measurement, the influence of the inherent noise, temperature, the calculation method of electric field, the additional phase difference and the angle adjustment precision on the accuracy of the measurement results is analyzed from many objective factors of the accuracy. And a corresponding suppression method is proposed for the source of the error with the larger influence. The performance of the device is calibrated and tested under a uniform electric field with a brass plate electrode. The results show that the electric field measurement at low voltage and the actual value of the electric field have good agreement with the change of the waveform and the numerical value. The minimum measurable peak of the device is 3.49k V/ mm. The maximum error is only 3.56%, and the problem of low measurement sensitivity and accuracy is solved. The effect of temperature and water on the electric field in oil under the action of impact voltage is studied. The results show that under the standard lightning impulse voltage of 60k V, with the increase of the temperature, the electric field in the oil has a downward trend, the lower amplitude at the peak is up to 9.2%, the lower amplitude is the largest at the time of 60 鈩，
本文编号：2502291
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