适用于同塔混压线路跨电压故障的距离保护新方法

Novel Distance Protection Method for Multi-voltage Lines on the Same Tower under Cross-voltage Fault

跨线故障是同塔多回输电线路的典型故障类型。同塔混压多回线路的跨线阻抗计算需考虑不同电压等级线路阻抗参数的差异性。本文提出了适用于同塔混压双回线路和典型同塔混压四回线路的跨电压等级的跨线阻抗计算方法。此方法将阻抗参数不同的两回线路的跨线阻抗用其中一回线的正序阻抗表示,同时考虑了线间零序互感的影响,并据此提出了基于跨电压等级跨线阻抗的距离保护I段的应用新方法。EMTP仿真表明,采用所提出方法计算的跨线阻抗可以正确反映故障点到保护安装处的距离。

Cross-line fault is a typical type of fault for multi-circuit transmission lines on the same tower. The calculation of cross-line impedance of multi-voltage multi-circuit lines on the same tower needs to take the differences between impedance parameters of lines at different voltage levels into account. In this paper,a calculation method for cross-voltage cross-line impedance,which is suitable for multi-voltage double-circuit lines and typical multi-voltage four-circuit lines on the same tower,is proposed. This method uses the positive-sequence impedance of one circuit to represent the cross-line impedance of two circuits with different impedance parameters;meanwhile,it considers the influence of zerosequence mutual inductance between lines. On this basis,a novel application method for the first-zone distance protection is proposed based on cross-voltage cross-line impedance. Simulation results with EMTP show that the cross-line impedance calculated by the proposed method can reflect the distance from the fault location to the installation position of protection.