接地参数计算与接地网频率响应特性下的研究
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摘要
发电厂、变电站良好的接地是电力系统安全运行的根本保证。接地网不仅为变电站内的各种电气设备提供一个公共的参考地,而且能将电力系统发生故障时的故障电流泄入大地,以此确保设备和人身的安全。
为了保障发电厂、变电站的安全运行,对符合实际情况的接地参数进行计算是极其重要的。早期的接地设计把土壤看成均匀半无限大介质,利用简化公式对接地电阻进行估计,但这种估计常导致计算结果与实测结果相差甚远,所以土壤分层结构模型的确立是进行接地系统数值分析的关键。通过对各地发电厂、变电站接地网长期观测统计发现,流经接地网较多的是雷电流,而雷电流是一种单极性脉冲信号,不但波头很陡而且还包含极其丰富的频率分量,因此不能用传统工频下的分析方法来分析雷电流流经接地网泄流过程。所以很有必要对高频雷电流入地时进行地网的时域、频率响应的研究,以此加强电力系统的安全运行。
本文主要研究内容分为如下几个部分：首先研究了接地网接地参数的计算方法,利用矩量法求解了接地网的各种参数,并与Matlab接口进行数据的后处理；其次利用复镜像法求解多层土壤中的格林函数来计算土壤分层结构；然后利用散离FFT变换进行雷电流的离散,计及雷电流入地时火花放电和土壤非线性特性的影响,分析计算了各种频率下的频率响应和时域响应。并通过模拟试验,利用示波器进行数据采集来分析雷电流注入接地网的时域响应,与理论分析的结果进行对比,验证了接地计算程序的正确性,最后改变雷电波波头时间和模拟接地网面积,分析了二个因素对冲击接地电阻的影响。
Good grounding of the substations can provide fundamental protection for safe operation of power system. Grounding grid not only provide a reference ground for various electric devices in the substation but also drains the fault current to the ground in order to ensure personal safety and equipment safety.
In order to assure safe operation of the substations, it is extremely important to calculate the realistic grounding parameter. The soil is considered as semi-infinite medium in early design of grounding and Grounding resistance is estimated using simplified formula, however, Such estimates often cause great errors between calculation and experimental, So the key of numerical analysis of the grounding system is establishment of the soil layered structure model. Through long-term observation and statistics of the grounding grid of substation and power plants, it is found that lightning current flowing through the grounding is the most, however, lighting current is a unipolar pulse, which not only has very steep front but also very rich frequency components. Therefore, traditional analytical method under power frequency can't be used to analyze the discharge process of lightning current flowing through the grounding grid. So it is necessary to So it is necessary to research the time domain and frequency response of high-frequency lightning flowing through grounding grid in order to enhance the safe operation of power system.
The main research topic as follows:firstly, calculation method of grounding grid parameters are studied, moment method is used to solve the parameters of grounding grid and connected with the MATLAB interface with the data post-processing. Secondly, complex image method is used to solve Green's function in order to calculate soil structure. Thirdly, using FFT transform to discrete lightning current, considering influence of spark discharge and non-linear characteristics of the soil when lightning current flows through grounding grid, frequency and time-domain response under every frequency is calculated and analyzed. Through simulation, using the oscilloscope for date acquisition, the time-domain response of the lightning current into the grounding is analyzed, which is compared with the result of theoretical analysis to verify the he program of grounding. At last, changing the wave front of lightning and the area of grounding grid, the impact of these factors are analyzed.
为了保障发电厂、变电站的安全运行,对符合实际情况的接地参数进行计算是极其重要的。早期的接地设计把土壤看成均匀半无限大介质,利用简化公式对接地电阻进行估计,但这种估计常导致计算结果与实测结果相差甚远,所以土壤分层结构模型的确立是进行接地系统数值分析的关键。通过对各地发电厂、变电站接地网长期观测统计发现,流经接地网较多的是雷电流,而雷电流是一种单极性脉冲信号,不但波头很陡而且还包含极其丰富的频率分量,因此不能用传统工频下的分析方法来分析雷电流流经接地网泄流过程。所以很有必要对高频雷电流入地时进行地网的时域、频率响应的研究,以此加强电力系统的安全运行。
本文主要研究内容分为如下几个部分：首先研究了接地网接地参数的计算方法,利用矩量法求解了接地网的各种参数,并与Matlab接口进行数据的后处理；其次利用复镜像法求解多层土壤中的格林函数来计算土壤分层结构；然后利用散离FFT变换进行雷电流的离散,计及雷电流入地时火花放电和土壤非线性特性的影响,分析计算了各种频率下的频率响应和时域响应。并通过模拟试验,利用示波器进行数据采集来分析雷电流注入接地网的时域响应,与理论分析的结果进行对比,验证了接地计算程序的正确性,最后改变雷电波波头时间和模拟接地网面积,分析了二个因素对冲击接地电阻的影响。
Good grounding of the substations can provide fundamental protection for safe operation of power system. Grounding grid not only provide a reference ground for various electric devices in the substation but also drains the fault current to the ground in order to ensure personal safety and equipment safety.
In order to assure safe operation of the substations, it is extremely important to calculate the realistic grounding parameter. The soil is considered as semi-infinite medium in early design of grounding and Grounding resistance is estimated using simplified formula, however, Such estimates often cause great errors between calculation and experimental, So the key of numerical analysis of the grounding system is establishment of the soil layered structure model. Through long-term observation and statistics of the grounding grid of substation and power plants, it is found that lightning current flowing through the grounding is the most, however, lighting current is a unipolar pulse, which not only has very steep front but also very rich frequency components. Therefore, traditional analytical method under power frequency can't be used to analyze the discharge process of lightning current flowing through the grounding grid. So it is necessary to So it is necessary to research the time domain and frequency response of high-frequency lightning flowing through grounding grid in order to enhance the safe operation of power system.
The main research topic as follows:firstly, calculation method of grounding grid parameters are studied, moment method is used to solve the parameters of grounding grid and connected with the MATLAB interface with the data post-processing. Secondly, complex image method is used to solve Green's function in order to calculate soil structure. Thirdly, using FFT transform to discrete lightning current, considering influence of spark discharge and non-linear characteristics of the soil when lightning current flows through grounding grid, frequency and time-domain response under every frequency is calculated and analyzed. Through simulation, using the oscilloscope for date acquisition, the time-domain response of the lightning current into the grounding is analyzed, which is compared with the result of theoretical analysis to verify the he program of grounding. At last, changing the wave front of lightning and the area of grounding grid, the impact of these factors are analyzed.
引文
[1]李景禄,胡毅.实用接地技术.中国电力出版社,2002：89-112
[2]何金良,曾嵘.电力系统接地技术.科学出版社,2007：49-115
[3]Frank Wenner.A method of measuring earth resistivity.bulletin, Washington,-60-DC:National Bureau of Standards,1915,16(11):12-58
[4]Hans R Seedher, J K Arora.Estimation of Two Layer Soil Parameters UsingFinite Wenner Resistivity Expressions.IEEE Transaction on Power Delivery,1992,7(3):1213-1217
[5]Huina Yang, Jiansheng Yuan, and Wei Zong. Determination of Three-layer EarthModel from Wenner Four-probe Test Data. IEEE Transactions on Magnetics,2001,37(5):3684-3687
[6]Dawalibi F.Earth resistivity measurement interpretation techniques. IEEE Trans. Power Apparatus and Systems,1984,103(2):374-382
[7]潘文霞,邹鹰.双层土壤的优化计算.中国电机工程学报.1996,16(5)：358-360
[8]潘文霞.不均匀土壤参数计算.高电压技术,1996,22(4)：31-33
[9]杨慧娜,袁建生.利用Wenner四极法确定三层土壤模型.清华大学学报,2002,42(3)：291-294
[10]P.J.Lagace, J. Fortin, E.D.Crainic. Interpretation of resistivity sounding measurements in n-layer soil using electrostatic images.IEEE Transaction on power Delivery, Vol.11, No.3, July,1992:1349-1354
[11]J.L del Alamo, E.E.A comparison among eight different techniques to achieve an optimum estimation of electrical grounding parameters in two-layered earth. IEEE Transaction on power Delivery, Vol.8, No.4, October 1993:1890-1899
[12]CIGRE WG 36.04.Guide on electromagnetic compatibility in electric power plants and substations, Publication No.124, Paris:CIGRE,1997.
[13]H B Dwight. Calculation of Resistances to Ground.IEEE Transactions, 1936,9(8):1319-1328
[14]E D Sunde.Earth Conduction Effects in Transmission Systems.New York:D VanNostrand Company Inc.1949:123-126
[15]J Zaborszky.Efficiency of Grounding Grids with Nonuniform Soil.IEEE Trans.Power Apparatus and Systems,1955,74(7):1230-1233
[16]B Thapar and K K Puri.Mesh Potentials in High-voltage Grounding Grids.IEEETrans.Power Apparatus and Systems,1967,86:249-254·
[17]Roger F Harrington.Field Computation by Moment Methods.New York:Macmillan,1968:23-33
[18]Trinh N Giao, Maruvada P Sarma.Effect of Two-layer Earth on the Electric Field near HVDC Ground Electrodes.IEEE Trans.Power Apparatus and Systems,1972,91(5):2356-2365
[19]Robert J Heppe.Computation of Potential at Surface above an Energized Grid orOther Electrode, Allowing for Non-uniform Current Distribution.IEEE Trans.Power Apparatus and Systems,1979, 98(6):1978-1989
[20]Pierre Kouteynikoff.Numerical Computation of Grounding Resistance of Sub-stations and Towers.IEEE Trans.Power Apparatus and Systems,1980, 99(3):957-965
[21]F Dawalibe, D Mukhedkar.Transferred Earth Potentials in Power Systems.IEEETrans.Power Apparatus and Systems,1978,97(1):90-101
[22]F Dawalibe, D Mukhedkar.Influence of Ground Rods on Grounding Grids. IEEE Trans.Power Apparatus and Systems,1979,98(6):2089-2097
[23]Y Leonard Chow.Complex Images for Electrostatic Field Computation in Multi-layered Media.IEEE Transactions on Microwave Theory and Techniques,1991,39(7):1120-1125
[24]R.Verma, D.Mukhedkar, Impulse Impedance of Buried Ground Wire, IEEE Trans.Power Apparatus and Systems,1980,99(5):2003-2007
[25]B.R.Gupta, B.Thapar, Impulse Impedance of Grounding Grids, IEEE Trans.Power Apparatus and Systems,1980,99(6):2357-2362
[26]R.Verma, D.Mukhedkar, Fundamental Considerations and Impulse Impedance of Grounding Grids, IEEE Trans. Power Apparatus and Systems,1981,100(3):1023-1030
[27]A.P.Meliopoulos, R.P.Webb, and E.B.Joy, Analysis of Grounding Systems, IEEE Trans.Power Apparatus and Systems,1981,100(3):1039-1048
[28]I.D.Lu, R.M.Shier, Application of a Digital Signal Analyzer to the Measurement of Power System Ground Impedances, IEEE Trans.Power Apparatus and Systems,1981,100(4):1918-1922
[29]A.P.Meliopoulos, M.GMoharam, Transient Analysis of Grounding Systems, IEEE Trans.Power Apparatus and Systems,1983,102(2):389-397
[30]M.M.Babu Narayanan, S.Parameswaran, D.Mukhedkar, Transient Performance of Grounding Grids, IEEE Transaction on Power Delivery, 1989,4(4):2053-2059
[31]Y L Chow, J J Yang and K D Srivastava.Grounding resistance of buried electrodes in multilayer earth predicted by sample voltage measurements along with surface-a theoretical discussion.IEEE Transactions on Power Delivery,1995,10(2):707-715
[32]IEEE-SA Standards Board.IEEE Guide for Safety in AC Substation Grounding. IEEE Std 80-2000
[33]F P Dawalibi.Electromagnetic Fields Generated by Overhead and Buried ShortConductors.Part 1 and Part 2, IEEE Transaction on Power Delivery, 1986, 1(4):105-119
[34]谢广润.电力系统接地技术.北京：水利电力出版社,1991：21-52
[35]文习山.接地体接地参数的数值计算与模拟实验.武汉：武汉水利电力大学,1985：58-116
[36]颜怀梁,陈先禄,李定中.接地计算方法及应用不均匀网孔改善地网电位分布的计算研究.重庆大学学报,1985,7 (4)：130-139
[37]戴江江.发、变电所(站)大地网接地问题边界单元法计算.武汉水利电力学院学报,1984,16(1)：51-62
[38]李光中,陈彩屏,赵初元.边界原法在基础接地中的应用——混凝土基础桩接地电阻的计算.电工技术学报,1991,1991(3)：59-63
[39]Jiansheng Yuan, Huina Yang, Liping Zhang. Simulation of Substation Grounding Grids with Unequal-Potential.IEEE Trans.on Magn,2000, 36(4):1468-1471
[40]王洪泽.计算水平地网接地电阻的新公式[J].高电压技术,1987,13(1)：74-79
[41]鲁志伟,陈慈萱.任意形状接地网接地电阻的计算.中国电力,1994,3：19-20
[42]潘文霞,陈慈萱.地网接触电势和跨步电势的简化计算.中国电机工程学报,1990,19(2)：47-53
[43]鲁志伟.大型地网跨步电势的简化计算.高电压技术,1992,18(2)：38-44
[44]王洪泽.复合接地网接地电阻的简化计算.电力建设,1996,7(5)：20-24
[45]王先冲.电磁场理论及应用.北京：科学出版社,1991：85-152
[46]唐章宏,袁建生.复空间中两直线导体间互阻系数的计算.电工技术杂志,2000,20(4)：4-5
[47]卡兰塔罗夫,采伊特林.电感计算手册.北京：机械工业出版社,1992：14-25
[48]F. Dawalibi, J.Ma, R.D.Southey. Behavior of grounding systems in multilayer soils:a parametric analysis. IEEE Transaction on Power Delivery,1994,9(1):1505-1508
[49]鲁志伟.大型接地网工频接地参数的计算和测量.武汉：武汉大学,2004：24-58
[50]曾嵘.高土壤电阻率地区变电站接地技术的研究.北京：清华大学,2001：25-98
[51]张小青.垂直接地体的冲击电阻与冲击系数.电力学报,2000,15(3)：155-156
[52]S.FurukawaO, Usuda, T. Isozaki. Development and Application of Lightning Arresters for Transmission Lines. IEEE Trans On PWRD,1989, 4(4):2121～2129.
[2]何金良,曾嵘.电力系统接地技术.科学出版社,2007：49-115
[3]Frank Wenner.A method of measuring earth resistivity.bulletin, Washington,-60-DC:National Bureau of Standards,1915,16(11):12-58
[4]Hans R Seedher, J K Arora.Estimation of Two Layer Soil Parameters UsingFinite Wenner Resistivity Expressions.IEEE Transaction on Power Delivery,1992,7(3):1213-1217
[5]Huina Yang, Jiansheng Yuan, and Wei Zong. Determination of Three-layer EarthModel from Wenner Four-probe Test Data. IEEE Transactions on Magnetics,2001,37(5):3684-3687
[6]Dawalibi F.Earth resistivity measurement interpretation techniques. IEEE Trans. Power Apparatus and Systems,1984,103(2):374-382
[7]潘文霞,邹鹰.双层土壤的优化计算.中国电机工程学报.1996,16(5)：358-360
[8]潘文霞.不均匀土壤参数计算.高电压技术,1996,22(4)：31-33
[9]杨慧娜,袁建生.利用Wenner四极法确定三层土壤模型.清华大学学报,2002,42(3)：291-294
[10]P.J.Lagace, J. Fortin, E.D.Crainic. Interpretation of resistivity sounding measurements in n-layer soil using electrostatic images.IEEE Transaction on power Delivery, Vol.11, No.3, July,1992:1349-1354
[11]J.L del Alamo, E.E.A comparison among eight different techniques to achieve an optimum estimation of electrical grounding parameters in two-layered earth. IEEE Transaction on power Delivery, Vol.8, No.4, October 1993:1890-1899
[12]CIGRE WG 36.04.Guide on electromagnetic compatibility in electric power plants and substations, Publication No.124, Paris:CIGRE,1997.
[13]H B Dwight. Calculation of Resistances to Ground.IEEE Transactions, 1936,9(8):1319-1328
[14]E D Sunde.Earth Conduction Effects in Transmission Systems.New York:D VanNostrand Company Inc.1949:123-126
[15]J Zaborszky.Efficiency of Grounding Grids with Nonuniform Soil.IEEE Trans.Power Apparatus and Systems,1955,74(7):1230-1233
[16]B Thapar and K K Puri.Mesh Potentials in High-voltage Grounding Grids.IEEETrans.Power Apparatus and Systems,1967,86:249-254·
[17]Roger F Harrington.Field Computation by Moment Methods.New York:Macmillan,1968:23-33
[18]Trinh N Giao, Maruvada P Sarma.Effect of Two-layer Earth on the Electric Field near HVDC Ground Electrodes.IEEE Trans.Power Apparatus and Systems,1972,91(5):2356-2365
[19]Robert J Heppe.Computation of Potential at Surface above an Energized Grid orOther Electrode, Allowing for Non-uniform Current Distribution.IEEE Trans.Power Apparatus and Systems,1979, 98(6):1978-1989
[20]Pierre Kouteynikoff.Numerical Computation of Grounding Resistance of Sub-stations and Towers.IEEE Trans.Power Apparatus and Systems,1980, 99(3):957-965
[21]F Dawalibe, D Mukhedkar.Transferred Earth Potentials in Power Systems.IEEETrans.Power Apparatus and Systems,1978,97(1):90-101
[22]F Dawalibe, D Mukhedkar.Influence of Ground Rods on Grounding Grids. IEEE Trans.Power Apparatus and Systems,1979,98(6):2089-2097
[23]Y Leonard Chow.Complex Images for Electrostatic Field Computation in Multi-layered Media.IEEE Transactions on Microwave Theory and Techniques,1991,39(7):1120-1125
[24]R.Verma, D.Mukhedkar, Impulse Impedance of Buried Ground Wire, IEEE Trans.Power Apparatus and Systems,1980,99(5):2003-2007
[25]B.R.Gupta, B.Thapar, Impulse Impedance of Grounding Grids, IEEE Trans.Power Apparatus and Systems,1980,99(6):2357-2362
[26]R.Verma, D.Mukhedkar, Fundamental Considerations and Impulse Impedance of Grounding Grids, IEEE Trans. Power Apparatus and Systems,1981,100(3):1023-1030
[27]A.P.Meliopoulos, R.P.Webb, and E.B.Joy, Analysis of Grounding Systems, IEEE Trans.Power Apparatus and Systems,1981,100(3):1039-1048
[28]I.D.Lu, R.M.Shier, Application of a Digital Signal Analyzer to the Measurement of Power System Ground Impedances, IEEE Trans.Power Apparatus and Systems,1981,100(4):1918-1922
[29]A.P.Meliopoulos, M.GMoharam, Transient Analysis of Grounding Systems, IEEE Trans.Power Apparatus and Systems,1983,102(2):389-397
[30]M.M.Babu Narayanan, S.Parameswaran, D.Mukhedkar, Transient Performance of Grounding Grids, IEEE Transaction on Power Delivery, 1989,4(4):2053-2059
[31]Y L Chow, J J Yang and K D Srivastava.Grounding resistance of buried electrodes in multilayer earth predicted by sample voltage measurements along with surface-a theoretical discussion.IEEE Transactions on Power Delivery,1995,10(2):707-715
[32]IEEE-SA Standards Board.IEEE Guide for Safety in AC Substation Grounding. IEEE Std 80-2000
[33]F P Dawalibi.Electromagnetic Fields Generated by Overhead and Buried ShortConductors.Part 1 and Part 2, IEEE Transaction on Power Delivery, 1986, 1(4):105-119
[34]谢广润.电力系统接地技术.北京：水利电力出版社,1991：21-52
[35]文习山.接地体接地参数的数值计算与模拟实验.武汉：武汉水利电力大学,1985：58-116
[36]颜怀梁,陈先禄,李定中.接地计算方法及应用不均匀网孔改善地网电位分布的计算研究.重庆大学学报,1985,7 (4)：130-139
[37]戴江江.发、变电所(站)大地网接地问题边界单元法计算.武汉水利电力学院学报,1984,16(1)：51-62
[38]李光中,陈彩屏,赵初元.边界原法在基础接地中的应用——混凝土基础桩接地电阻的计算.电工技术学报,1991,1991(3)：59-63
[39]Jiansheng Yuan, Huina Yang, Liping Zhang. Simulation of Substation Grounding Grids with Unequal-Potential.IEEE Trans.on Magn,2000, 36(4):1468-1471
[40]王洪泽.计算水平地网接地电阻的新公式[J].高电压技术,1987,13(1)：74-79
[41]鲁志伟,陈慈萱.任意形状接地网接地电阻的计算.中国电力,1994,3：19-20
[42]潘文霞,陈慈萱.地网接触电势和跨步电势的简化计算.中国电机工程学报,1990,19(2)：47-53
[43]鲁志伟.大型地网跨步电势的简化计算.高电压技术,1992,18(2)：38-44
[44]王洪泽.复合接地网接地电阻的简化计算.电力建设,1996,7(5)：20-24
[45]王先冲.电磁场理论及应用.北京：科学出版社,1991：85-152
[46]唐章宏,袁建生.复空间中两直线导体间互阻系数的计算.电工技术杂志,2000,20(4)：4-5
[47]卡兰塔罗夫,采伊特林.电感计算手册.北京：机械工业出版社,1992：14-25
[48]F. Dawalibi, J.Ma, R.D.Southey. Behavior of grounding systems in multilayer soils:a parametric analysis. IEEE Transaction on Power Delivery,1994,9(1):1505-1508
[49]鲁志伟.大型接地网工频接地参数的计算和测量.武汉：武汉大学,2004：24-58
[50]曾嵘.高土壤电阻率地区变电站接地技术的研究.北京：清华大学,2001：25-98
[51]张小青.垂直接地体的冲击电阻与冲击系数.电力学报,2000,15(3)：155-156
[52]S.FurukawaO, Usuda, T. Isozaki. Development and Application of Lightning Arresters for Transmission Lines. IEEE Trans On PWRD,1989, 4(4):2121～2129.