土壤冻结对变电站地表绝缘安全性能的影响
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摘要
土壤冻结地网后,地表接触电压、跨步电压会急剧增加。同时由于土壤电阻率的增加,地表绝缘层的绝缘性能亦会增强。IEEE Standard 80—2000以及国家标准GB/T 50065中给出的跨步电压、接触电压安全值表达式无法反映随着土壤冻结,冻土层结构对其安全值的影响。基于戴维南定理,利用仿真软件研究了土壤冻结后对土壤内阻所造成的影响。研究发现:土壤内阻仅由地表至地网间的土壤结构所决定,因此,土壤冻结至地网处后,土壤内阻主要由绝缘层及冻土层的土壤电阻率所决定;跨步电压下土壤内阻值约是接触电压下确定土壤内阻值的四倍,其结论与脚电阻理论相同;土壤冻结后,地表绝缘层的绝缘性能会显著增强,较上述标准确定的安全值提升1. 5倍左右。因此,按照本文结论可以减少冻土地区降阻及均压极的布置,具有一定经济价值。
The contact voltage and step voltage will increase sharply after the ground network is frozen. At the same time,due to the increase of soil resistivity,the performance of the insulation layer will also increase. The safety values of step voltage and contact voltage given in IEEE Standard 80—2000 and GB/T 50065 can not reflect the influence of frozen soil layer on its safety value. Based on Thevenin's theorem,this paper studied the effect of freezing soil on soil internal resistance by the use of simulation software.The study found: The soil internal resistance is only determined by the soil structure between the earth surface and the ground network,therefore,the soil resistance is mainly determined by the soil resistivity of the insulating layer and the frozen soil layer when the soil is frozen to the ground grid; the value of soil internal resistance of step voltage is about four times of that of contact voltage,and the conclusion is the same as that of foot resistance theory; After the soil is frozen,the performance of the insulation layer will be significantly increased,which is about 1. 5 times higher than the safety value determined by the above standards,Therefore,according to the conclusions of this paper,the number of the equipment of resistance reduction and pressure equalizing in permafrost areas can be reduced,which has certain economic value.
The contact voltage and step voltage will increase sharply after the ground network is frozen. At the same time,due to the increase of soil resistivity,the performance of the insulation layer will also increase. The safety values of step voltage and contact voltage given in IEEE Standard 80—2000 and GB/T 50065 can not reflect the influence of frozen soil layer on its safety value. Based on Thevenin's theorem,this paper studied the effect of freezing soil on soil internal resistance by the use of simulation software.The study found: The soil internal resistance is only determined by the soil structure between the earth surface and the ground network,therefore,the soil resistance is mainly determined by the soil resistivity of the insulating layer and the frozen soil layer when the soil is frozen to the ground grid; the value of soil internal resistance of step voltage is about four times of that of contact voltage,and the conclusion is the same as that of foot resistance theory; After the soil is frozen,the performance of the insulation layer will be significantly increased,which is about 1. 5 times higher than the safety value determined by the above standards,Therefore,according to the conclusions of this paper,the number of the equipment of resistance reduction and pressure equalizing in permafrost areas can be reduced,which has certain economic value.
引文
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[14]张云,张波,陈伟军,等.接地系统地面高阻层的特性[J].高电压技术,2015,41(5):1582-1588.ZHANG Yun,ZHANG Bo,CHEN Weijun,et al.Characteristics of surface high-resistance coverings in grounding system[J].High Voltage Engineering,2015,41(5):1582-1588.
[15]李谦,文习山,肖磊石.土壤特性对变电站接地网特性参数影响的数值分析[J].高电压技术,2013,39(11):2656-2663.LI Qian,WEN Xishan,XIAO Leidan.Numerical analysis of influence of Soil characteritic on characteristic parameters of substation grounding grid[J].High Voltage Engineering,2013,39(11):2656-2663.
[16]庄池杰,曾嵘,张波,等.高土壤电阻率地区变电站接地网设计思路[J].高电压技术,2008,34(5):893-897.ZHUANG Chijie,ZENG Rong,ZHANG Bo,et al.Grounding system design method in high Soil resistivity regions[J].High Voltage Engineering,2008,34(5):893-897.
[17]何金良,曾嵘.电力系统接地技术[M].北京:科学出版社,2007.
[18]左鹏,魏冲,邹军,等.不等间距布置导体的接地网优化设计[J].高电压技术,2011,37(9):2315-2320.ZUO Peng,WEI Chong,ZOU Jun,et al.Optimal design of grounding grid in which conductor unequally spaced[J].High Voltage Engineering,2011,37(9):2315-2320.
[2]HE J L,ZENG R,GAO Y Q,et al.Seasonal influences on safety of substation grounding system[J].IEEE Transactions on Power Delivery,2003,18(3):788-795.
[3]IEEE S,td 80-2000.IEEE guide for safety of AC Substation groundings[S],2000.
[4]GB 50065-2011交流电气装置的接地设计规范[S],2011.GB 50065-2011.Code for design of ac electrical installations earthing[S].National standard of the People’s Republic of China,2011.
[5]宋景博,潘文霞,普珍,等.考虑接触电压的风电机组接地网优化设计[J].电瓷避雷器,2013(6):56-60.SONG Jingbo,PAN Wenxia,PU Zhen,et al.Optimization design of wind turbine grounding grid considering touch voltage[J].Insulators and Surge Arresters,2013(6):56-60.
[6]薛洁,张小青,刘成华,等.一种计算变电站接地网电阻的简化方法[J].电瓷避雷器,2012(2):95-99.XUE Jie,ZHANG Xiaoqing,LIU Chenghua,et al.[6]a simplified method for calculating the substation grounding grid resistance[J].Insulators and Surge Arresters,2012(2):95-99.
[7]孙为民,何金良,曾嵘,等.季节因素对发变电站地表高阻层安全效果的影响[J].中国电力,2000,33(1):62-64.SUN Weimin,HE Jinliang,ZENG Rong,et al.Influence of seasonal factor on safety of ground surface high resistivity layer in substations[J].Electric Power,2000,33(1):62-64.
[8]何金良,康鹏,曾嵘,等.青藏铁路110kV输变电工程五道梁和沱沱河变电站的土壤结构模型分析[J].电网技术,2005,29(20):10-14.HE Jinliang,KANG Peng,ZENG Rong,et al.Soil structural model analysis of wudaoliang and tuotuohe substations for 110kV power transmission engineering of Qinghai-Tibet railway[J].Power System Technology,2005,29(20):10-14.
[9]何金良,康鹏,曾嵘,等.青藏铁路110kV输变电工程五道梁和沱沱河变电站的接地系统设计[J].电网技术,2006,30(4):60-64.HE Jinliang,KANG Peng,ZENG Rong,et al.Grounding system design of wudaoliang and tuotuohe substations for 110KV power transmission engineering of QinghaiTibet railway[J].Power System Technology,2006,30(4):60-64.
[10]HE Jinliang,ZHANG Baoping,KANG Peng,et al.Lightning impulse breakdown characteristics of frozen soil[J].IEEE Transactions on Power Delivery,2008,23(4):2216-2223.
[11]郭在华,邢天放,吴广宁,等.冰冻土壤中垂直接地极的接地电阻变化规律[J].高电压技术,2014,40(3):698-706.GUO Zaihua,XING Tianfang,WU Guangning,et al.Grounding resistance change rule of vertical grounding electrode in frozen Soil[J].High Voltage Engineering,2014,40(3):698-706.
[12]李生林,吴广宁,曹晓斌,等.影响双层土壤中垂直接地极性能的研究[J].电瓷避雷器,2007(5):35-38.LI Shenglin,WU Guangning,CAO Xiaobin,et al.Study of influence factors of dual-layered Soil on vertical grounding rod performance[J].Insulators and Surge Arresters,2007(5):35-38.
[13]杨方圆,王森,李志忠,等.垂直接地极的降阻性能研究[J].陕西电力,2010,38(1):1-5.YANG Fangyuan,WANG Sen,LI Zhizhong,et al.Research on vertical grounding rod performance[J].Shaanxi Electric Power,2010,38(1):1-5.
[14]张云,张波,陈伟军,等.接地系统地面高阻层的特性[J].高电压技术,2015,41(5):1582-1588.ZHANG Yun,ZHANG Bo,CHEN Weijun,et al.Characteristics of surface high-resistance coverings in grounding system[J].High Voltage Engineering,2015,41(5):1582-1588.
[15]李谦,文习山,肖磊石.土壤特性对变电站接地网特性参数影响的数值分析[J].高电压技术,2013,39(11):2656-2663.LI Qian,WEN Xishan,XIAO Leidan.Numerical analysis of influence of Soil characteritic on characteristic parameters of substation grounding grid[J].High Voltage Engineering,2013,39(11):2656-2663.
[16]庄池杰,曾嵘,张波,等.高土壤电阻率地区变电站接地网设计思路[J].高电压技术,2008,34(5):893-897.ZHUANG Chijie,ZENG Rong,ZHANG Bo,et al.Grounding system design method in high Soil resistivity regions[J].High Voltage Engineering,2008,34(5):893-897.
[17]何金良,曾嵘.电力系统接地技术[M].北京:科学出版社,2007.
[18]左鹏,魏冲,邹军,等.不等间距布置导体的接地网优化设计[J].高电压技术,2011,37(9):2315-2320.ZUO Peng,WEI Chong,ZOU Jun,et al.Optimal design of grounding grid in which conductor unequally spaced[J].High Voltage Engineering,2011,37(9):2315-2320.
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