高土壤电阻率地区多回路变电站接地设计研究
Research on the Earth Grid Design of the Substation with Multi Circuit Transmission Line in High Soil Resistivity Area
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摘要:
高土壤电阻率地区变电站降阻成本高，在安全的前提下提高最大允许接地电阻可有效提高工程的经济性。研究了变电站出线数量对系统短路电流、故障分流系数和故障入地电流的影响，以及对最大允许接地电阻的影响。其中，针对简易分流系数计算公式的局限和误差，建议在多回路变电站接地设计中采用计算机建模。基于国内西南地区某220 kV变电站，采用CDEGS软件对其进行了接地分析计算。计算表明：考虑变电站出线数量变化能减小最大故障入地电流设计值，有效提高最大允许接地电阻，从而提高工程的经济性。 Abstract:By Increasing the maximum allowed earth resistance on safety premise, the high cost of reducing the earth resistance of substations in high soil resistivity area can be effectively controlled. Therefore, this paper analysis the influence of circuit number to the system fault current, split factor and ground fault current, further the maximum allowed earth resistance. It is suggested to use computer simulation instead of simple formula to calculate the split factor, so as to overcome the problem of limitation and deviation of the formula. CDEGS is employed to analysis a 220 kV substation in the southwest of China. The results show that a smaller design value of ground fault current can be obtained when the circuit changes is considered. That is effective to increase the maximum allowed earth resistance and enhance economics.
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