【摘要】：電力變壓器是電力系統(tǒng)的核心,其絕緣設(shè)計(jì)是重中之重。沖擊電壓下油紙絕緣結(jié)構(gòu)的電場(chǎng)分布特性是變壓器絕緣設(shè)計(jì)的關(guān)鍵環(huán)節(jié),能夠準(zhǔn)確測(cè)得在沖擊電壓下變壓器油紙絕緣油中電場(chǎng)及其隨溫度、水分的變化特性,對(duì)于改善其絕緣設(shè)計(jì),提升變壓器絕緣強(qiáng)度及電網(wǎng)過(guò)電壓水平有著重大意義。沖擊電壓是單極性脈沖電壓,容易產(chǎn)生大量的空間電荷,而目前大多數(shù)變壓器沖擊電場(chǎng)的計(jì)算均為利用仿真軟件基于容性場(chǎng)等效進(jìn)行,無(wú)法考慮空間電荷對(duì)電場(chǎng)所造成的影響,只能根據(jù)理論計(jì)算結(jié)果結(jié)合許用場(chǎng)強(qiáng)選擇合理的裕度作為設(shè)計(jì)值。但仿真結(jié)果缺乏實(shí)際測(cè)量的支撐與驗(yàn)證,沖擊電壓下的電場(chǎng)特性尚不明朗。針對(duì)目前沖擊電壓下油紙絕緣油中電場(chǎng)測(cè)量仍然存在測(cè)量靈敏度和準(zhǔn)確度較低的問(wèn)題,本文基于Kerr效應(yīng)原理,提出了沖擊電壓下油紙絕緣油中電場(chǎng)非接觸式的實(shí)際測(cè)量方法,研制了一套由光路系統(tǒng)、光電轉(zhuǎn)換器件、有機(jī)玻璃密封腔體、沖擊電壓源、溫度水分循環(huán)控制系統(tǒng)構(gòu)成的油紙絕緣空間電場(chǎng)測(cè)量裝置,為后續(xù)油紙絕緣油中電場(chǎng)測(cè)量奠定了基礎(chǔ)。針對(duì)電場(chǎng)測(cè)量準(zhǔn)確性問(wèn)題,從準(zhǔn)確性受到的諸多客觀因素方面從發(fā),分析了固有噪聲、溫度、電場(chǎng)計(jì)算方法、附加相位差及角度調(diào)節(jié)精度等多個(gè)方面對(duì)測(cè)量結(jié)果準(zhǔn)確性的影響,并對(duì)影響較大的誤差來(lái)源提出相應(yīng)的抑制方法。利用黃銅平板電極在均勻電場(chǎng)下對(duì)裝置性能進(jìn)行了標(biāo)定和檢驗(yàn),研究結(jié)果表明:在低電壓下的電場(chǎng)測(cè)量值與電場(chǎng)實(shí)際值在波形變化及數(shù)值上取得了很好的一致性,裝置最小可測(cè)峰值為3.49k V/mm的雷電沖擊電場(chǎng),最大誤差僅為3.56%,解決了測(cè)量靈敏度和準(zhǔn)確度較低的問(wèn)題。開(kāi)展了溫度和水分對(duì)沖擊電壓作用下油中電場(chǎng)的影響研究。研究結(jié)果表明:在60k V的標(biāo)準(zhǔn)雷電沖擊電壓下,隨著溫度的上升,油中電場(chǎng)總體呈下降趨勢(shì),在波峰處下幅程度最大,25℃時(shí)下幅已達(dá)9.2%,60℃時(shí)下幅程度最大,峰值處下降41.6%;在100k V的標(biāo)準(zhǔn)雷電沖擊電壓下,水分含量較低時(shí),油中電場(chǎng)與外施電場(chǎng)差別不大,隨著油中水分含量的上升,油中電場(chǎng)總體呈下降趨勢(shì),在波峰處尤為明顯,最大下降幅度達(dá)到20.5%。試驗(yàn)結(jié)果定性分析如下:隨著油中溫度的上升,油電阻率下降,根據(jù)已有的參考文獻(xiàn)可得,油中由陽(yáng)極板發(fā)射的正離子遷移速率加快,在很短的時(shí)間內(nèi)越過(guò)了電場(chǎng)測(cè)量點(diǎn),從而削弱了空間電場(chǎng);由于水是強(qiáng)極性分子,極化效應(yīng)明顯,隨著油中水分的增加,單位體積內(nèi)水分子數(shù)目隨之增加,極化效應(yīng)對(duì)外施電場(chǎng)的削弱也越來(lái)越明顯。
[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，

本文編號(hào)：2502291