一种输电线路特殊接线方式对线路距离保护影响研究

Effect on the line distance protection when the transmission lines are connected in a special mode

建立了同杆双回输电线路串接入单回输电线路的数学模型,分析了常用的线路距离保护受到的影响。分析结果表明:距离保护会受到一定程度的影响,其影响程度与系统方式、线路参数以及故障点位置有关,定值整定时需对距离保护灵敏度进行校核。编制了全线故障点扫描软件,图形化展示灵敏度情况,供定值整定人员参考。针对距离保护灵敏度问题提出了两种解决方案。根据实际工程参数建立RTDS仿真模型并接入了实际使用线路保护装置,进行了验证性测试。测试表明,超范围整定的距离Ⅱ段或者纵联距离灵敏度整定不合适时,确有可能出现保护拒动的情况。最后再次强调了应尽量从一次系统规划上避免出现这种特殊的接线方式。

A mathematical model that double-circuit line in the same tower is connected to a single-circuit line in series is established.The effect on the common distance protection is analyzed.The result indicates that the effect is relevant to system operation mode,line parameters and the fault location,and the sensitivity of distance protection should be verified when setting the settings.Sensitivity check software is compiled,which can provide the calculation and display of measurement impedance trajectory,and the sensitivity displayed as a graphical mode can be referred.Two solutions for the sensitivity of the distance protection are proposed.A RTDS simulation model based on the actual parameters on site and connected with real line distance relays is established.The confirmatory test based on the RTDS simulation indicates that overreached zone 2 and pilot distance relay maybe not operate if the sensitivity is incorrect.Finally,it is emphasized that the special connecting mode should be avoided when planning and designing primary system.