基于过渡电阻有功功率的单相高阻接地保护

Single-phase High-resistance Fault Protection Based on Active Power of Transition Resistance

输电线路单相高阻接地时故障特征不明显,容易造成保护拒动,对此提出基于过渡电阻有功功率的保护新原理,作为高阻故障的后备保护。首先利用接地距离元件测量阻抗、线路正序阻抗以及两端保护实测电流形成保护动作量。该动作量在区内单相高阻故障时为过渡电阻的有功功率,其值大于零,在区外各类型故障时其值等于零,二者存在明显差异。然后采用线路两端实测电压电流构造保护自适应动作门槛,可以根据故障情况自动调整输出结果,防止保护误动。在此基础上,提出基于过渡电阻有功功率保护的动作判据用于实现故障判断。理论和仿真分析表明,该保护能够准确反映单相高阻接地故障,无需数据同步,对两侧系统运行方式变化、线路非全相运行以及系统振荡的影响不敏感,具有很高的灵敏性和可靠性。

The weak fault features in the single-phase high-resistance faults easily make protection refuse to operate. Therefore a novel backup protection for high-resistance faults based on the active power of transition resistance was proposed. Firstly, the operation value was confirmed by the measured impedance of ground distance elements, line positive sequence impedance and the two-terminal currents of lines. When an internal single-phase high-resistance fault occurs, the operation value equals the active power consumed by transition resistance and is greater than zero. When an external fault occurs, the operation value equals zero. The difference between the two is obvious. Then a self-adaptive threshold was zonstituted by measured voltage and current to prevent 3rotection from mal-operation. The threshold value can be tdjusted automatically with fault conditions. Based on those, he action criterion of this protection scheme was presented. analysis and simulations demonstrated that the novel rotection can accurately judge single-phase high-resistance aults without data synchronization. Moreover, this protection immune to the various operation conditions of two terminal ystems, two-phase operation of transmission lines and system scillation. The protection has high sensitivity and reliability.