直流接地极及杆塔接地网附近电磁场的有限元分析
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摘要
高压直流输电系统处于单极大地回线运行方式时,有很大的直流电流通过直流接地极流入大地,这将造成接地极本身及附近输电杆塔接地网的腐蚀。在理论分析接地极和杆塔接地网电磁场的基础上,应用有限元分析软件COMSOL Multiphysics,以德宝直流输电工程千阳接地极为例,建立了多层大地土壤结构下的直流接地极和杆塔接地网数值模型,添加相关边界条件,进行网格划分处理,计算分析了接地极地表电位分布规律,并对杆塔接地网附近电位及泄漏电流密度进行了研究,结果发现:接地极地表电位沿径向距离逐渐降低;杆塔接地网本体上的电位最高,接地网的射线末端泄漏电流密度最大,射线首端的泄漏电流密度最小,接地网矩形与射线的连接处电流密度有突变。该研究对掌握直流接地极及杆塔接地网周围电场分布情况和腐蚀规律,具有重要的意义。
When the HVDC power system operates in the single pole ground return mode, there is a large amount of DC current flowing into the earth through the grounding electrode,causing corrosion of the grounding electrode and nearby transmission line grounding grid. Based on the theoretical analysis of the electromagnetic field of ground pole and tower grounding grid, this paper applies the finite element analysis software COMSOL Multiphysics to the Qianyang grounding electrode of the Deyang-Baoji DC transmission project(as an example), and establishes the numerical models of grounding electrode and tower grounding grid under a multilayer soil structure, calculating and analyzing the distribution law of the ground electrode surface potential by mesh processing and adding the related boundary conditions, and in addition, the paper studies the potential and leakage current density near the tower grounding grid. The study result shows that the grounding electrode surface potential is gradually reduced along the radial distance; the potential on the body of tower grounding grid is the highest; and the leakage current density at the end terminal of the grounding grid is the largest while the leakage current density in the head terminal of the radial is the smallest; and there is a sudden change of the current density at the junction between the grounding grid rectangle and the radial. The research in this paper is of great significance to grasp the distribution of electric field and corrosion law around grounding electrode and tower grounding grid.
When the HVDC power system operates in the single pole ground return mode, there is a large amount of DC current flowing into the earth through the grounding electrode,causing corrosion of the grounding electrode and nearby transmission line grounding grid. Based on the theoretical analysis of the electromagnetic field of ground pole and tower grounding grid, this paper applies the finite element analysis software COMSOL Multiphysics to the Qianyang grounding electrode of the Deyang-Baoji DC transmission project(as an example), and establishes the numerical models of grounding electrode and tower grounding grid under a multilayer soil structure, calculating and analyzing the distribution law of the ground electrode surface potential by mesh processing and adding the related boundary conditions, and in addition, the paper studies the potential and leakage current density near the tower grounding grid. The study result shows that the grounding electrode surface potential is gradually reduced along the radial distance; the potential on the body of tower grounding grid is the highest; and the leakage current density at the end terminal of the grounding grid is the largest while the leakage current density in the head terminal of the radial is the smallest; and there is a sudden change of the current density at the junction between the grounding grid rectangle and the radial. The research in this paper is of great significance to grasp the distribution of electric field and corrosion law around grounding electrode and tower grounding grid.
引文
[1]赵畹君,谢国恩,曾南超,等.高压直流输电工程技术[M].北京:中国电力出版社,2011.
[2]杨晓萍.高压直流输电与柔性交流输电[M].北京:中国电力出版社,2010.
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[4]曹林,赵杰,张波,等.高压直流输电直线型接地极系统分析[J].高电压技术,2006,32(2):92-94.CAO Lin,ZHAO Jie,ZHANG Bo,et al.Analysis of HVDC linear ground electrode system[J].High Voltage Engineering,2006,32(2):92-94.
[5]陈水明,施广德,赵智大.圆环形直流输电接地极电流场分析[J].高电压技术,1994(1):3-7.CHEN Shuiming,SHI Guangde,ZHAO Zhida.Analysis of current fields near ring-type HVDC ground electrodes[J].High Voltage Engineering,1994 20(1):3-7.
[6]高理迎,郭贤珊,董晓辉.接地极入地电流对杆塔腐蚀及防护研究[J].中国电力,2009,42(12):38-41.GAO Liying,GUO Xianshan,DONG Xiaohui.Research on preventing corrosion of electric tower caused by grounding current of DC electrode[J].Electric Power,2009,42(12):38-41.
[7]朱轲,吴驰,扬威.直流接地极对附近输电线路杆塔的腐蚀影响及防护措施的研究[J].高压电器,2011,47(10):41-47.ZHU Ke,WU Chi,YANG Wei.Research on the corrosion influence of the HVDC earth electrode on the nearby transmission line towers and the towers’protective measures[J].High Voltage Apparatus,2011,47(10):41-47.
[8]刘连光,马成廉.基于有限元方法的直流输电接地极多层土壤地电位分布计算[J].电力系统保护与控制,2015,43(18):1-5.LIU Lianguang,MA Chenglian.Calculation of multi-layer soil earth surface potential distribution of HVDC due to finite element method[J].Power System Protection and Control,2015,43(18):1-5.
[9]朱岸明,王森,胡攀峰,等.德宝直流输电对750 kV宝鸡主变压器运行影响研究[J].电网与清洁能源,2010,26(12):67-70.ZHU Anming,WANG Sen,HU Panfeng.et al.Influences of the Deyang-Baoji DC transmission line on the 750 kVpower transformer in Baoji power substation[J].Power System and Clean Energy,2010,26(12):67-70.
[10]魏刚,齐卫东,惠华.±500 kV宝鸡-德阳直流输电工程接地极参数测试方法分析[J].陕西电力,2010,38(3):42-45.WEI Gang,QI Weidong,HUI Hua.Analysis on ground electrodes test method of Baoji-Deyang±500 kV HVDCtransmission project[J].Shaanxi Electric Power,2010,38(3):42-45.
[11]冷迪.±500 kV宝德直流系统对极址附近输电线路及750 kV变压器影响研究[D].重庆:重庆大学,2012.
[12]刘伟龙.直流输电工程接地极对输电线路腐蚀作用的模拟研究[D].荆州:长江大学,2015.
[13]董晓辉,杨威,唐程,等.特高压直流入地电流对附近杆塔地网腐蚀评估[J].高电压技术,2009,35(7):1546-1552.DONG Xiaohui,YANG Wei,TANG Cheng,et al.Corrosion effects and evaluation method of UHV power line tower grounding collection caused by DC current[J].High Voltage Engineering,2009,35(7):1546-1552.
[2]杨晓萍.高压直流输电与柔性交流输电[M].北京:中国电力出版社,2010.
[3]陆继明,肖冬,毛承雄,等.直流输电接地极对地表电位分布的影响[J].高电压技术,2006,32(9):55-58.LU Jiming,XIAO Dong,MAO Chengxiong,et al.Analysis of effects of DC earthed pole on earth surface potential distributions[J].High Vlotage Engineering,2006,32(9):55-58.
[4]曹林,赵杰,张波,等.高压直流输电直线型接地极系统分析[J].高电压技术,2006,32(2):92-94.CAO Lin,ZHAO Jie,ZHANG Bo,et al.Analysis of HVDC linear ground electrode system[J].High Voltage Engineering,2006,32(2):92-94.
[5]陈水明,施广德,赵智大.圆环形直流输电接地极电流场分析[J].高电压技术,1994(1):3-7.CHEN Shuiming,SHI Guangde,ZHAO Zhida.Analysis of current fields near ring-type HVDC ground electrodes[J].High Voltage Engineering,1994 20(1):3-7.
[6]高理迎,郭贤珊,董晓辉.接地极入地电流对杆塔腐蚀及防护研究[J].中国电力,2009,42(12):38-41.GAO Liying,GUO Xianshan,DONG Xiaohui.Research on preventing corrosion of electric tower caused by grounding current of DC electrode[J].Electric Power,2009,42(12):38-41.
[7]朱轲,吴驰,扬威.直流接地极对附近输电线路杆塔的腐蚀影响及防护措施的研究[J].高压电器,2011,47(10):41-47.ZHU Ke,WU Chi,YANG Wei.Research on the corrosion influence of the HVDC earth electrode on the nearby transmission line towers and the towers’protective measures[J].High Voltage Apparatus,2011,47(10):41-47.
[8]刘连光,马成廉.基于有限元方法的直流输电接地极多层土壤地电位分布计算[J].电力系统保护与控制,2015,43(18):1-5.LIU Lianguang,MA Chenglian.Calculation of multi-layer soil earth surface potential distribution of HVDC due to finite element method[J].Power System Protection and Control,2015,43(18):1-5.
[9]朱岸明,王森,胡攀峰,等.德宝直流输电对750 kV宝鸡主变压器运行影响研究[J].电网与清洁能源,2010,26(12):67-70.ZHU Anming,WANG Sen,HU Panfeng.et al.Influences of the Deyang-Baoji DC transmission line on the 750 kVpower transformer in Baoji power substation[J].Power System and Clean Energy,2010,26(12):67-70.
[10]魏刚,齐卫东,惠华.±500 kV宝鸡-德阳直流输电工程接地极参数测试方法分析[J].陕西电力,2010,38(3):42-45.WEI Gang,QI Weidong,HUI Hua.Analysis on ground electrodes test method of Baoji-Deyang±500 kV HVDCtransmission project[J].Shaanxi Electric Power,2010,38(3):42-45.
[11]冷迪.±500 kV宝德直流系统对极址附近输电线路及750 kV变压器影响研究[D].重庆:重庆大学,2012.
[12]刘伟龙.直流输电工程接地极对输电线路腐蚀作用的模拟研究[D].荆州:长江大学,2015.
[13]董晓辉,杨威,唐程,等.特高压直流入地电流对附近杆塔地网腐蚀评估[J].高电压技术,2009,35(7):1546-1552.DONG Xiaohui,YANG Wei,TANG Cheng,et al.Corrosion effects and evaluation method of UHV power line tower grounding collection caused by DC current[J].High Voltage Engineering,2009,35(7):1546-1552.