基于六相参数信息的不换位同塔双回线距离保护研究

Research on the Distance Protection Performance for Common-tower Un-transposed Double-circuit Transmission Lines Based on Six-phase Parameter Information

指出不换位同塔双回线发生故障时,保护的测量阻抗不仅受线间互感的影响,还要受到本回线各序分量相互耦合的作用,使得测量阻抗精度难以满足距离保护的要求。阐明了直接使用两回线电气量及六相阻抗矩阵对故障回路列写电压平衡方程,从而推导出适用于不换位同塔双回线各种故障类型下的距离保护算法。以理论分析和PSCAD数字仿真证明,该算法能承受线路较大的不对称性且耐过渡电阻能力高,具有良好的距离保护动作性能。

When a fault occurs on un-transposed double-circuit transmission lines, the measurement of impedance is not only affected by mutual inductance between the parallel lines, but also influenced by coupling effects between positive, negative and zero sequence generated by fault lines, which makes it difficult to satisfy the requirement of distance protection. The distance protection algorithm which is adaptable to various fault types occurred on the un-transposed common-tower double-circuit transmission lines is derived to form voltage equation for the fault loops by directly using electrical quantities of the parallel lines and six-phase impedance matrix. Theoretical analysis and numerical simulation performed by PSCAD show that the algorithm has an excellent distance protection performance, which can withstand a greater degree of asymmetry and big transition resistance.