基于变电站稳态监测信息的小电阻接地系统单相接地检测性能提升方法

Improvement of single-phase grounding fault detection for small resistance ground⁃ing systems based on steady-state monitoring information in the substation

为了利用已有硬件资源提高小电阻接地系统单相接地选线性能,研究了基于变电站自动化系统的全局稳态监测信息用于单相接地选线的方法。推导单相接地时母线零序电压和各条线路的零序电流,计算极端情况下单相接地故障线路与健全线路的零序电流幅值之比,提出单相接地选线方法,指出以线路的零序电流作为单相接地选线的启动条件,并给出零序电流的整定原则,计算零序电流整定值下能够启动的最大过渡电阻。结合实例对所提方法进行验证,结果表明利用变电站自动化系统的稳态监测信息能够显著提升小电阻接地系统单相接地检测性能。

In order to use the existing hardware sources to improve the line selection performance of single-phase grounding fault of small resistance grounding systems,a method for line selection of single-phase grounding fault based on the global steady-state monitoring information of the substation automation system is investigated.The zerosequence voltage of the busbar and the zero-sequence current of each line in the case of single-phase grounding faults are deduced.The ratio of zero-sequence current of lines with single-phase grounding faults to that of non-fault lines under extreme conditions is analyzed.Moreover,the line selection method of single-phase grounding fault is proposed.The zero-sequence current is used as the starting criterion for line selection of single-phase grounding fault,and the setting principle of zero-sequence principle is introduced to calculate the maximum transition resis⁃tance that can be started under the setting value of zero-sequence current.An example is given to illustrate the pro⁃posed method,and the results show that the steady-state monitoring information of the substation automation system can remarkably improved the detection performance of single-phase grounding fault of small resistance grounding systems.