纵联阻抗在单电源输电线路中的运用

Application of the pilot impedance to the single power supply transmission lines

在系统分析基于单电源及双电源下输电线路纵联阻抗阻值差异并完整保留原有纵联阻抗推导结论的基础上,合理修改了纵联阻抗电气数据的关联相量关系,并准确地调整了输电线路纵联保护故障甄别的动作门槛以能够扩展并能够适应基于单电源下输电线路的运行环境。该计算方法采用工频故障分量为纵联阻抗的计算电气量,在得到工频线路电容补偿的条件下,当计算得到的阻抗幅值小于设定数值时可断定发生了区内故障;反之可以断定在被保护区内没有发生故障。该算法能有效改进单电源下输电线路纵联保护的性能。在EMTP仿真中,建立了一条1000kV500km单电源输电线路的仿真模型,进行了基于各种故障条件下的仿真验证,仿真结果验证了这个算法在单电源环境下具有足够的稳定性和充分的可靠性。

We modify the correlative phasor relationship of the pilot impedance electrical data and adjust the opreation threshold of fault identification of transmission line pilot protection to extend and may meet the running environment of the transmission lines based on the single power supply, through systematically analyzing the impedance value difference of the transmission line pilot impedance based on single power supple and double power supply and completely reserving the original derived result of the pilot impedance. This computational method adopts the power frequency fault components as the calculating electrical quantities of the pilot impedance, under the condition of compensating power frequency line capacitances, it may be determined that the internal fault occurs when the impedance amplitude is smaller than the setting value, conversely, it can be judged non-fault occurring in the protected region. This algorithm can effectively improve the performance of the transmission line pilot protection under the single power supply. In EMTP simulation, we establish the transmission line simulation model of single power supply of a 1000 kV 500 km, and execute simulation verifications based on each fault. The simulation results indicate that this computational method has enough stability and sufficient reliability in the single Dower supply environment.