發(fā)布時間：2018-03-05 15:06

  本文選題：變電站地網(wǎng)　切入點：接地裝置測試　出處：《電子科技大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：變電站的接地系統(tǒng)是維護(hù)電力系統(tǒng)安全、可靠運(yùn)行以及電力設(shè)備安全、人員安全的根本保證和重要措施。系統(tǒng)發(fā)生故障時,極大的短路電流經(jīng)接地系統(tǒng)泄流,使得地網(wǎng)的電位發(fā)生升高,若地網(wǎng)的接地阻抗較大,地電位的升高可能會危及設(shè)備和人身安全。據(jù)統(tǒng)計,我國曾發(fā)生多起因地網(wǎng)接地未達(dá)到要求所導(dǎo)致的事故或者事故擴(kuò)大,這些由接地系統(tǒng)引起的事故損失大都在數(shù)百萬元以上,間接經(jīng)濟(jì)損失更為嚴(yán)重。4隨著電網(wǎng)的發(fā)展、電壓等級的提高以及系統(tǒng)容量的增大,接地短路電流將相當(dāng)大,大型地網(wǎng)覆蓋面積廣、對角線長,為保證系統(tǒng)安全、可靠運(yùn)行,對接地系統(tǒng)的要求需要更為嚴(yán)格。目前,國內(nèi)流行采用異頻法測量一般地網(wǎng)的接地電阻,對于大型地網(wǎng)采用異頻法或大電流工頻法。工頻大電流法能準(zhǔn)確測量地網(wǎng)接地電阻,但測量過程復(fù)雜,需要倒相來消除零序?qū)y量結(jié)果的影響,抗干擾能力差;異頻法與工頻大電流法相比,能消除地網(wǎng)的高頻干擾,測量結(jié)果不受系統(tǒng)電源的影響,但實驗電流較小,不能真實反映大型地網(wǎng)的運(yùn)行狀態(tài)。大型地網(wǎng)除接地電阻外,由于電抗的影響,在土壤電阻率低的地方,其感性分量很可能比阻性分量大,感性分量也不能忽略,另外,接觸電位、跨步電位、場區(qū)地表電位梯度能反映地網(wǎng)運(yùn)行的狀態(tài),在大型地網(wǎng)測量也不可忽略。為準(zhǔn)確掌握大型地網(wǎng)狀態(tài),精確測量大型地網(wǎng)相關(guān)參數(shù),本項目深入研究異頻法,在一般異頻法基礎(chǔ)上,汲取工頻大電流法優(yōu)點,提出采用大電流異頻信號對大型、不均勻地網(wǎng)進(jìn)行測量,成功開發(fā)了大電流異頻測試系統(tǒng),既能可有效消除干擾對測量結(jié)果的影響,又能實現(xiàn)地網(wǎng)跨步電壓、接觸電勢、場區(qū)地表電位梯度分布曲線等參數(shù)測量,可進(jìn)行多次重復(fù)測量,消除了偶然因素影響,能真實反映大型地網(wǎng)的運(yùn)行狀態(tài),滿足現(xiàn)場測量的需要,具有較高的實用價值。
[Abstract]:The grounding system of substation is the fundamental guarantee and important measure to maintain the safety and reliability of power system, the safety of power equipment and the safety of personnel. If the grounding impedance of the grounding grid is large, the increase of the ground potential may endanger the equipment and personal safety. According to statistics, there have been many accidents or accidents caused by the grounding failure to meet the requirements in our country. Most of these accidents caused by grounding system are more than millions of yuan. The indirect economic loss is more serious. With the development of power network, the increase of voltage level and the increase of system capacity, the grounding short-circuit current will be quite large. In order to ensure the safety and reliability of the system, the requirements of grounding system should be more strict. At present, it is popular to use different frequency method to measure the grounding resistance of general ground grid in our country. Different frequency method or high current power frequency method is used for large scale ground network. The power frequency and large current method can accurately measure grounding resistance of ground grid, but the measuring process is complicated, so it is necessary to eliminate the influence of zero sequence on the measurement result by inverting phase, and the anti-interference ability is poor. Compared with the power frequency and high current method, the different frequency method can eliminate the high frequency interference of the ground net, and the measurement results are not affected by the power supply of the system, but the experimental current is small and can not truly reflect the operation state of the large ground network. Because of the influence of reactance, the inductive component of soil resistivity is likely to be larger than that of resistive component, and the inductive component can not be ignored. In addition, the contact potential, stride potential, and the gradient of surface potential in the field area can reflect the operation state of the earth network. In order to accurately grasp the state of large-scale ground network and accurately measure the related parameters of large-scale ground network, this project deeply studies the method of different frequency, and based on the general method of different frequency, draws the advantage of power frequency and large current method. It is proposed that the large and uneven ground net be measured by using the high current different frequency signal, and the large current different frequency measurement system is developed successfully. The system can not only effectively eliminate the influence of interference on the measurement results, but also realize the step voltage and contact potential of the ground network. The field area surface potential gradient distribution curve and other parameters measurement can be repeated many times, eliminating the influence of accidental factors, can truly reflect the operation of large-scale ground network, meet the needs of the field survey, has a higher practical value.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM862
，

本文編號：1570745