同杆双回线路故障选相研究

发布时间：2018-03-25 12:21

本文选题：同杆双回线　切入点：特征分析　出处：《河南理工大学》2015年硕士论文

【摘要】：为了节约输电走廊通道资源,降低电力建设成本,同时提高线路单位走廊输电容量和土地利用率,同杆双回线路已成为我国220kV及以上输电线路的首选,并且往往作为电网的主干线路担负着电网超大功率传输或区域电网的联络重任,因此其安全可靠的运行对电网有极其重要的影响。同杆双回线路的两回线间距离较近,存在跨线故障,同时因线间互感的作用,故障特征更加复杂,传统单回线路选相元件应用于双回线路尤其是跨线故障时易出现误动作。因此论文对同杆双回线路进行故障特征分析,提取故障电流特征信号,同时借助PSCAD/EMTDC仿真平台验证故障特征分析结果,并进一步探讨故障类型、故障位置、过渡电阻对故障电流特征信号的影响,在此基础上提出新型同杆双回线路工频量故障选相方法。该方法共分两步实现,首先,利用同名相和电流的相分量特性,将同杆双回线路故障等价为单回线系统故障,根据等价单回线系统的电气量选出故障相别;然后,在选出故障相的基础上,根据两回线同名相电流的比值规律特性,确定具体故障相线。由仿真结果可得,两步选相法不受故障类型、过渡电阻等的影响,对窄线间距的双回线路能保证线路80%可靠选相,然而该选相方法在线路近端时可能误选相,借助于其他辅助判据能得到进一步改善。针对目前同杆双回线路的选相研究多是基于工频量,暂态量方面的研究鲜有成果的现状,为适应新型暂态保护的选相需求,在提出两步选相法的基础上,进一步深入研究同杆双回线路的暂态量选相。暂态量选相方案以两步故障选相法为选相机理,利用小波变换工具提取同名相和电流、同名相电流的小波暂态能量,以暂态能量为判据,构成新型的同杆双回线路暂态量故障选相原理。仿真验证了暂态量选相方法的可行性,不仅弥补了工频量选相在线路近端可靠性不足的缺点,而且很大程度上提高了选相速度,改善了保护性能。此外,论文对同杆双回线路的工频量选相和暂态量选相进行对比研究,分析各自的优缺点,对全面系统的故障选相研究具有重要作用。
[Abstract]:In order to save the transmission corridor resources, reduce the power construction cost, and improve the transmission capacity and land utilization ratio of the unit corridor, the double-circuit transmission line with the same pole has become the first choice of 220kV and above transmission lines in China. And as the main line of the power network, it often bears the heavy responsibility of super power transmission or regional power transmission, so its safe and reliable operation has an extremely important influence on the power network. The distance between the two circuit lines of the double-circuit line with the same pole is close. There are cross-line faults, and the fault features are more complicated because of the mutual inductance between lines. The traditional single circuit phase selection element is easy to misoperate in double circuit line, especially in cross line fault. Therefore, the fault characteristic analysis of the same pole double circuit line is carried out in this paper, and the fault current characteristic signal is extracted. At the same time, the results of fault feature analysis are verified by PSCAD/EMTDC simulation platform, and the influence of fault type, fault location and transition resistance on fault current characteristic signal is further discussed. On this basis, a new phase selection method for power frequency fault of double-circuit line with the same pole is proposed. The method is realized in two steps. Firstly, the fault of double-circuit line with the same pole is equivalent to the fault of single-circuit system by using the phase component characteristics of the same phase and current. The fault phase is selected according to the electrical quantity of the equivalent single circuit system, and then, on the basis of selecting the fault phase, the specific fault phase line is determined according to the ratio characteristics of the phase current of the same name of the two circuit lines. The two-step phase selection method is not affected by fault type, transition resistance, etc. The two-circuit circuit with narrow line spacing can guarantee 80% reliable phase selection. However, the phase selection method may misselect the phase at the near end of the line. With the aid of other auxiliary criterions, the phase selection of double-circuit lines with the same pole can be further improved. In view of the fact that the current research on phase selection is based on the power frequency and transient quantity, it is necessary to meet the needs of phase selection for the new type of transient protection. On the basis of the two-step phase selection method, the transient phase selection of the double-circuit transmission line with the same pole is further studied. The two-step fault phase selection method is used as the camera principle, and the phase and current of the same name are extracted by wavelet transform. The wavelet transient energy of the phase current of the same name, based on the transient energy, constitutes a new principle of phase selection for transient fault of a double-circuit transmission line with the same pole. The feasibility of the transient phase selection method is verified by simulation. It not only makes up for the deficiency of reliability of power frequency phase selection near the line, but also improves the speed of phase selection and the performance of protection to a great extent. In this paper, the power frequency phase selection and the transient phase selection of the double-circuit line are compared and analyzed, which plays an important role in the fault phase selection of the overall system.
【学位授予单位】：河南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM75

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