高压地下电缆自适应继电保护方案的研究

针对电力电缆与架空线路电气参数的不同,分别从电力电缆分布电容以及零序阻抗两方面出发,提出了适用于高压地下电缆的自适应保护方案。通过对采用电容电流补偿和不采用电容电流补偿的分相电流差动保护的动作行为的比较分析,证明了电容电流补偿的必要性,提出了基于电容电流半补偿的分相电流差动保护方案。由于电缆线路零序阻抗非线性特性对保护性能产生很大的影响,精确计算电缆线路零序阻抗是非常必要的,故提出了基于迭代算法的自适应零序电流保护方案的思路与步骤。

Research on schemes of adaptive protective relaying for transmission lines with high voltage underground cables

To the difference of electrical parameters between AC cables and overhead cables, an adaptive protection schemes for high voltage underground cables is proposed, from two aspects of AC cables distributive capacitance and zero-sequence impedance. The compensation of capacitance current is very necessary according to the comparison analysis of the performance of the current phase differential protection with and without capacitance current compensation. The half compensation method is proposed for the current phase differential protection and the result shows capacitance current compensation method can improve the security and sensitivity of the differential protection. As the non-linearity of the zero-sequence impedance of pipe-type cable influences the performance of the zero-sequence overcurrent protection, it is necessary to calculate the zero-sequence impedance accurately. The adaptive scheme for zero-sequence protection based on iterative algorithm is proposed in this paper.