直流接地极招弧角熄弧能力研究

发布时间：2018-10-24 21:03

【摘要】：本文以糯扎渡电站送电广东±800kV直流输电工程的普洱换流站接地极线路为对象,主要研究不同因素对直流电弧特性的影响、直流接地极招弧角安装方式以及招弧角与直流接地极线路的绝缘配合方法。论文首先调研和总结了直流电弧特性和招弧角理论和工程应用的研究现状,直流接地极招弧角熄弧能力除了受到电磁力、热浮力、风力等因素影响之外,主要与招弧角的安装方式、间隙距离以及系统容量相关。结合实际直流接地极线路参数,建立直流接地极招弧角燃弧试验平台,对影响电弧特性的不同因素如电磁力、风力和招弧角形式及布置方式,开展了招弧角燃弧试验研究,通过高速摄像机记录电弧发展过程。研究结果表明:电磁力对电弧的转移和拉伸作用显著,相对而言,由于受到脉宽等因素限制,风速和热浮力作用不明显;最小放电间隙距离同为400mm时,羊角型招弧角电弧最终拉伸至约1400mm,而其他类型招弧角仅拉伸至1100~1200mm,表明羊角型招弧角的电弧拉伸能力最强,最有利于电弧的熄灭。结合招弧角电弧电磁力的计算,研究招弧角安装方式,分析安装(角度)方式、故障位置和杆塔接地电阻对电磁力的影响规律,并给出了招弧角安装方式的建议。研究结果表明:当招弧角平行于输电线路安装、且朝向接地极侧时(α=0°),电弧受到的电磁力最大,电弧最易远离绝缘子串;当故障点位置靠近接地极侧,杆塔接地电阻增大时,电弧电流减小,电弧受到的电磁力减弱。最后,通过招弧角间隙燃弧试验获取电弧伏安特性曲线,并与直流输电系统输出特性曲线相结合,提出招弧角与直流输电线路的绝缘配合方法,基于该方法给出不同招弧角间隙距离对应直流输电线路的保护范围,并提出了提高招弧角保护范围的建议。研究结果表明:对于一定间隙距离的招弧角而言,随着杆塔接地电阻的增大,线路的保护范围变大。不考虑电弧拉长,当间隙距离为650mm时,若杆塔接地电阻Rt=5Ω,保护范围约为5%;若杆塔接地电阻Rt=15Ω,保护范围略约为20%。此外,增加接地极导线回数可提高招弧角保护范围。取杆塔接地电阻Rt=5Ω,对1000mm间隙的招弧角,当接地极导线回数由2提高到6时,其保护范围由5%至12%,提升约2倍,改善效果显著。
[Abstract]:In this paper, the earth pole line of Pu'er converter station in Guangdong 卤800kV DC transmission project of Nuozhadu Hydropower Station is taken as the object, and the influence of different factors on DC arc characteristics is studied. The installation method of DC earth contact arc angle and the method of insulation coordination between DC earth contact angle and DC earth pole line. In this paper, the characteristics of DC arc and the theory and engineering application of DC arc angle are investigated and summarized. Besides electromagnetic force, thermal buoyancy, wind force and so on, the DC earth contact arc extinguishing ability is affected by the factors, such as electromagnetic force, thermal buoyancy, wind force and so on. It is mainly related to the installation method, gap distance and system capacity. Combined with the actual DC ground pole line parameters, the test platform of DC earth pole arc firing angle is established. The experimental research on the different factors such as electromagnetic force, wind force, arc angle form and arrangement mode is carried out for the influence of arc characteristics. The arc development is recorded by a high-speed camera. The results show that the effect of electromagnetic force on arc transfer and tension is significant, but the effect of wind speed and thermal buoyancy is not obvious because of the limitation of pulse width, and the minimum discharge gap distance is the same as 400mm. Finally, the arc of angle-type arc is drawn to about 1400mm, while the other type of arc angle is only stretched to 1100m ~ 1200mm, which indicates that the arc drawing ability of angle-type arc angle is the strongest, which is most favorable to the extinction of arc. Combined with the calculation of the electromagnetic force of the arc, this paper studies the installation mode of the arc angle, analyzes the influence of the installation (angle) mode, the fault location and the grounding resistance of the tower on the electromagnetic force, and gives some suggestions for the installation mode of the arc stroke angle. The results show that when the arc angle is parallel to the transmission line and is oriented towards the earth-pole side (伪 = 0 掳), the arc is subjected to the largest electromagnetic force, and the arc is most easily away from the insulator string, and when the fault point is near the ground pole side, the grounding resistance of the tower increases. The current of the arc decreases and the electromagnetic force of the arc decreases. Finally, the arc volt-ampere characteristic curve is obtained by the arc firing test at the angle of stroke, and combined with the output characteristic curve of HVDC transmission system, and the insulation coordination method between the arc stroke angle and the HVDC transmission line is put forward. Based on this method, the protection range of HVDC transmission line corresponding to the gap distance of different arc stroke angle is given, and some suggestions to improve the protection range are put forward. The results show that the range of line protection becomes larger with the increase of the grounding resistance of the tower for the arc angle of a certain gap distance. When the gap distance is 650mm, the protection range is about 5 if the grounding resistance of the tower is Rt=5 惟, and about 20 if the grounding resistance of the tower is Rt=15 惟. In addition, the range of arc angle protection can be increased by increasing the number of earth pole conductors. When the grounding resistance Rt=5 惟 of the pole tower is taken, when the arc contact angle of the 1000mm gap is increased from 2 to 6, the protection range is from 5% to 12%, which is about 2 times higher, and the improvement effect is remarkable.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM721.1

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