【摘要】：隨著中國電力事業(yè)的不斷發(fā)展,投入使用的XLPE電纜及其附件也與日俱增。目前,投入使用的電纜及其終端隨著運行時間的增加,發(fā)生局部放電的可能性也在增大。自上世紀七十年代開始,已經(jīng)研究出各種局放檢測設(shè)備來研究局放發(fā)生的位置、局部放電量大小、老化程度等。在綜合考慮局部放電、水樹枝、電樹枝老化特征的情況下,本文構(gòu)建了一種基于高頻脈沖電流法的35kV電纜及其終端局部放電檢測智能診斷系統(tǒng)。 本文對電纜及其終端局部放電和水樹、電樹發(fā)生的原理、檢測方法及相關(guān)實驗結(jié)論做了系統(tǒng)分析。根據(jù)35kV電纜終端可能出現(xiàn)局放的位置,利用有限元法對不同大小和形狀的局放缺陷模型進行1：1建模仿真,以便研究電纜終端內(nèi)部場強分布、電勢分布等特征,并進一步了解電纜終端內(nèi)部局放發(fā)生機理,并對其老化診斷提供理論參考。仿真分析得出：電纜終端銅屏蔽層斷口處是發(fā)生局放的薄弱環(huán)節(jié),具有較高的局部場強；在可能產(chǎn)生局部放電的各處位置,割傷缺陷較凹陷缺陷有更大的場強,更容易發(fā)生局部放電。電纜終端缺陷模型形狀越尖銳,電場畸變越嚴重,場強越大。銅屏蔽層斷口附近存在氣隙等缺陷時,局部場強大于空氣擊穿場強30kV/mm,極易產(chǎn)生局放,且越靠近斷口處場強越大。 本文將粗糙集和神經(jīng)網(wǎng)絡(luò)相結(jié)合的故障診斷方法應用于電纜終端的局放類型模式識別和老化診斷分析。以此方法為根據(jù),配合虛擬儀器技術(shù)和高頻脈沖電流傳感器及專業(yè)局放數(shù)據(jù)采集設(shè)備構(gòu)建了35kV電纜及其終端局部放電檢測智能診斷系統(tǒng)。所構(gòu)建的系統(tǒng)可實現(xiàn)對實時數(shù)據(jù)進行頻譜分析,查看歷史數(shù)據(jù),粗糙集—神經(jīng)網(wǎng)絡(luò)智能診斷以及用戶信息管理等工作。 本文通過采用粗糙集—神經(jīng)網(wǎng)絡(luò)聯(lián)合診斷方法與只依靠BP神經(jīng)網(wǎng)絡(luò)的診斷算法對比得出：粗糙集—神經(jīng)網(wǎng)絡(luò)相結(jié)合的診斷方法具有更好的局放類型識別率和容錯性,且訓練時間低于BP神經(jīng)網(wǎng)絡(luò)方法。
[Abstract]:With the continuous development of China's electric power industry, the XLPE cable and its accessories are also increasing day by day. At present, with the increase of running time, the possibility of partial discharge is also increasing. Since the 1970s, a variety of partial discharge detection equipment has been developed to study the location, local discharge capacity, aging degree and so on. Considering the aging characteristics of partial discharge, water branch and electric branch, an intelligent diagnosis system for partial discharge detection of 35kV cable and its terminal based on high frequency pulse current method is constructed in this paper. In this paper, the principle, detection method and related experimental conclusions of partial discharge and water tree and electric tree in cable and its terminal are systematically analyzed. According to the possible location of local discharge at 35kV cable terminal, the 1:1 modeling simulation of local discharge defect model with different sizes and shapes is carried out by using finite element method, in order to study the characteristics of field intensity distribution and potential distribution in cable terminal. The mechanism of local discharge in cable terminal is further understood, and the theoretical reference for aging diagnosis is provided. The simulation results show that the break of copper shield layer at cable terminal is the weak link of partial discharge and has high local field strength. In the positions where partial discharge may occur, the cutting defect has greater field strength than the sunken defect, and is more prone to partial discharge. The sharper the shape of the cable terminal defect model is, the more serious the electric field distortion is, and the larger the field strength is. When there are air gap and other defects near the fracture surface of copper shield layer, the local field strength is larger than the air breakdown field strength of 30 kV 鈮，

本文編號：2483928