CAJ | 학술논문

特高压换流变压器绝缘承受的直流电压高，绝缘缺陷劣化发展迅速，且单凭局部放电（PD）量值和放电次数无法对绝缘缺陷的发展阶段进行分析诊断。为此，研究了特高压换流变压器内部油纸绝缘缺陷直流局部放电特征及其发展过程，构建了油纸针一板等7种局部放电模型。采用阶梯式升压法研究在长期外加电压作用下，绝缘纸板从起始放电到被击穿的整个缺陷发展过程中脉冲电流信号的实时特征及其统计特性，通过拍照的方式给出各模型各发展阶段纸板表面电腐蚀状态，并给出各相应发展阶段电场的空间分布。结果表明：直流局部放电发展过程复杂，初期以大放电脉冲为主，放电频率低，等待恢复时间随机性强；中期和末期以小脉冲放电为主，等待恢复时间均匀分布；临界击穿时等待恢复时间分布集中。结合多种放电模型直流局部放电试验，可断定不同缺陷结构从起始直流局部放电到击穿的过程中，其局部放电的总体发展趋势表现一致。
특고압환류변압기절연승수적직류전압고，절연결함열화발전신속，차단빙국부방전（PD）량치화방전차수무법대절연결함적발전계단진행분석진단。위차，연구료특고압환류변압기내부유지절연결함직류국부방전특정급기발전과정，구건료유지침일판등7충국부방전모형。채용계제식승압법연구재장기외가전압작용하，절연지판종기시방전도피격천적정개결함발전과정중맥충전류신호적실시특정급기통계특성，통과박조적방식급출각모형각발전계단지판표면전부식상태，병급출각상응발전계단전장적공간분포。결과표명：직류국부방전발전과정복잡，초기이대방전맥충위주，방전빈솔저，등대회복시간수궤성강；중기화말기이소맥충방전위주，등대회복시간균균분포；림계격천시등대회복시간분포집중。결합다충방전모형직류국부방전시험，가단정불동결함결구종기시직류국부방전도격천적과정중，기국부방전적총체발전추세표현일치。
The direct-current (DC) withstand voltage of ultra high voltage (UHV) converter transformer is high and defects of insulators degrade rapidly. However, the developing process of the defects cannot be diagnosed only by partial discharge (PD) and discharge times. Thus, the developing process and characteristics of the defects on ultra high voltage converter transformer oil-paper insulation were researched, and seven common defects models were established. The high voltage was increased step-by-step from PD inception voltage until the model was broken down, and the pulse current signal's real-time characteristics and statistical properties during the developing processes of defects were obtained. The cauterization on the board surface of the models under different phases was recorded by photos to study their changing processes; meanwhile, the spatial distribution of the electric field under different phases was obtained. The results show that the PD under DC condition has a complicated developing process: it is consisted of mainly large pulse discharges with a low frequency and random waiting-recovery times at the initial stage; the pulse discharge becomes smaller and the waiting-recovery time has a uniform distribution at the middle stage; and.then the waiting recovery time tends to focus at a certain value at critical stage till breaks down. Combined with the DC partial discharge test of different models, it is concluded that, regardless of the defect structure, the partial discharge follows an identical development trend from PD inception voltage until the model breaks down.