直流偏磁不确定因素建模分析

Modeling and Analysis of Uncertain Factors of DC Magnetic Bias

直流输电系统引起的直流偏磁会对电网安全稳定运行构成威胁。目前,直流偏磁问题定量模型已经比较清晰,但受不确定因素影响,得到直流偏磁会出现较大偏差,影响直流偏磁抑制设备的正确选型。在已知电位与相关参数经典函数的基础上,采用估计法对各影响参数进行不确定估计,并完成了不确定模型验证,给出了随着不确定因素变化地电位的变化情况。研究表明随着直流电流入地深度增加,地电位急剧下降,距离接地极5 km处,电位降到5 V以下。接地极地电位峰值随着大地电阻率的上升而线性增加,近区电阻率的影响要远大于中区及远区,中区及远区的大地电阻率上升基本不会对地电位峰值产生影响。

The direct current(DC)magnetic bias caused by the high voltage direct current(HVDC)transmission system will threaten the safe and stable operation of power grid.Currently,the quantitative model of DC bias has been relatively clear,however,DC bias will have a large deviation due to the influence of uncertain factors,which will affect the correct selection of DC bias suppression equipment.The uncertainty of each influencing parameter was estimated by the estimation method based on the known classical functions of potential and related parameters,and the verification of the uncertainty model was completed,which gave the variation of ground potential with the change of uncertain factors.The results show that the ground potential drops sharply with the increase of DC penetration depth,and the potential drops below 5 V at 5 km from the grounding electrode.The peak value of ground potential increases linearly with the increase of earth resistivity,and the influence of near⁃field resistivity is much greater than that of middle and far areas,and the rise of earth resistivity in middle and far areas has little effect on the peak value of ground potential.