雷云下空间电荷对直流输电线路上行先导起始特性的影响

发布时间：2018-12-31 13:38

【摘要】：以往在分析直流输电线路上行先导的起始过程时,一般只考虑了雷云、下行先导以及直流运行电压对输电线路附近电场的影响,而未充分考虑输电线路周围早已存在的空间电荷对原来电场所带来的畸变。为此,对上行先导起始前的一系列放电过程进行了研究,包括雷云所导致的地表空间电荷层、直流运行电压所引起的离子流电荷层等,并比较了这些过程对上行先导起始特性的影响。分析发现,上行先导起始前线路周围空间电荷的分布主要决定于运行电压及雷云,2者在输电线路周围所产生的空间电荷密度可超过10 nC/m3;相对来说,因雷云所导致的空间电荷层的电荷密度只有约1 nC/m3,故雷云对上行先导起始的影响可以忽略不计;另外,因下行先导只有在发展至较低高度时,才能产生与运行电压、雷云相当的影响,故下行先导对空间电荷分布的作用甚微。基于上述分析,建立了考虑离子流影响后的上行先导起始模型,并对实际的上行先导起始过程进行了仿真。与传统模型比较发现,考虑离子流影响后,下行先导必须发展至更低的高度才能使导线周围电场强度满足上行先导起始条件,导致上行先导的起始时间延后,这说明了直流输电线路的离子流有碍上行先导的起始。
[Abstract]:In the past, only the effects of thundercloud, downlink pilot and DC operating voltage on the electric field near the transmission line were considered when analyzing the starting process of the uplink forerunner of HVDC transmission line. The distortion caused by the space charge around the transmission line is not fully considered. For this reason, a series of discharge processes prior to the initiation of the uplink pilot are studied, including the surface space charge layer caused by the thundercloud, the ion current charge layer caused by the DC operating voltage, and so on. The effects of these processes on the initial characteristics of the uplink are compared. It is found that the distribution of space charge around the line before the upstream pilot initiation is mainly determined by the operating voltage and the thundercloud. The space charge density around the transmission line can exceed 10 nC/m3;. On the other hand, the effect of thundercloud on the initiation of the uplink is negligible because the space charge density of the space charge layer caused by the thundercloud is only about 1 nC/m3,. In addition, the downlink pilot has little effect on space charge distribution due to the fact that the downlink leader can produce a voltage equivalent to the operating voltage only when the downlink leader reaches a relatively low altitude, so the downlink pilot has little effect on the space charge distribution. Based on the above analysis, an uplink pilot initiation model considering the influence of ion current is established, and the actual upstream pilot initiation process is simulated. Compared with the traditional model, considering the influence of ion current, the downlink leader must develop to a lower height in order to make the electric field intensity around the conductor satisfy the initial condition of the uplink lead, which leads to the delay of the starting time of the uplink pilot. This shows that the ion current of DC transmission line hinders the initiation of uplink forerunner.
【作者单位】：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;南方电网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)(2011CB209403) 中国南方电网有限责任公司重点科技项目(K201014)~~
【分类号】：TM863

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