重复加压及直流预压过程对油纸绝缘局部放电特性的影响

发布时间：2018-01-07 05:45

本文关键词：重复加压及直流预压过程对油纸绝缘局部放电特性的影响　出处：《高电压技术》2015年02期 　论文类型：期刊论文

【摘要】：换流变压器出厂试验过程,经常遇到直流耐压试验结束后若干h内,交流耐压试验按照GB/T 18494.2执行无法顺利通过的问题,说明直流预压对油纸绝缘交流局部放电特性产生一定影响。为此,采用球-板电极模型模拟油纸绝缘系统中的稍不均匀电场,试验探究重复加压与直流预压过程对油纸绝缘局部放电特性的影响,重点对比分析纯交流初次加压、重复加压以及直流预压3种情况下的局部放电起始电压、临界击穿电压及熄灭电压变化规律。研究结果表明:重复加压过程会大幅减少绝缘系统的局部放电起始电压(降至约33.44%),临界击穿电压下降约7.84%,熄灭电压几乎不受影响,经过高压端接地约8~9 h后,系统内的局部放电耐受水平与初次升压过程水平相当;而直流预压过程会一定程度上减小系统的局部放电起始电压(降至约82.38%)、临界击穿电压(降至约89.75%),且随着直流预压水平的提高上述两参数降幅更加明显,熄灭电压几乎不受直流预压作用的影响,一般经过4~6 h高压端接地静置,直流预压过程对于油纸系统内局部放电特性的影响消失。基于多次试验结果,提出重复加压及直流预压过程产生的空间预存电荷是对交流电压下局部放电特性造成影响的主要原因。
[Abstract]:During the test process of converter transformer, the AC voltage test can not pass smoothly according to GB/T 18494.2 within a few hours after the DC voltage test is finished. It is shown that DC preloading has a certain effect on AC partial discharge characteristics of oil-paper insulation. Therefore, a slightly uneven electric field in oil-paper insulation system is simulated by using a spherical plate electrode model. The effects of repeated pressurization and DC preloading on partial discharge characteristics of oil-paper insulation were investigated, and the initial partial discharge voltage of pure AC primary pressurization, repeated pressurization and DC preloading was compared and analyzed. The variation of critical breakdown voltage and extinguishing voltage. The results show that the initial voltage of partial discharge of insulation system can be greatly reduced by repeated pressurization (to about 33.44). The critical breakdown voltage decreases about 7.84 and the extinguishing voltage is almost unaffected. After about 8h of high voltage termination, the partial discharge tolerance level in the system is similar to that in the first voltage boost process. The DC preloading process will reduce the initial voltage of partial discharge to a certain extent (to about 82.38) and the critical breakdown voltage (to about 89.75). With the increase of DC preloading level, the decrease of the above two parameters is more obvious, and the extinguishing voltage is almost independent of DC preloading. The effect of DC preloading on the partial discharge characteristics of oil-paper system disappeared, based on the results of multiple tests. It is pointed out that the space stored charge generated by the repeated pressurization and DC preloading is the main reason for the influence of the partial discharge characteristics under the AC voltage.
【作者单位】：国网电力科学研究院;清华大学电机工程与应用电子技术系电力系统及发电设备控制和仿真国家重点实验室;华北电力科学研究院有限责任公司;
【基金】：国家重点基础研究发展计划(973计划)(2011CB209400) 国家电网公司科技项目(20122000548)~~
【分类号】：TM855
【正文快照】： Effect of Re-applied and Pre-pressing DC Voltage on the Characteristics of PartialDischarge Within Oil-paper InsulationNIE Dexin1,WANG Mingyuan2,SHA Yanchao3,ZHOU Yuanxiang2,WU Zhirong1,DENG Jiangang1(1.State Grid Electric Power Research Institute,Wuhan

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