同杆双回线一体化保护与准三相运行研究

发布时间：2019-05-07 18:21

【摘要】：随着电力需求增长,同杆并架输电线因其出线走廊窄、输电容量大、供电可靠性高等优点在人多地少的国家和地区得到了广泛应用。我国220kV及以上电压等级同杆双回线数量日益增多,其中大多数为全程同杆并架。作为同杆双回线的首选主保护,分相纵联差动保护可靠性受到纵联通信通道制约,亟需基于单端电气量的保护作主后备。而传统距离保护应用于同杆双回线时,选相元件和测量阻抗元件受到跨线故障与线间互感影响,容易误动或拒动。本论文提出将同杆双回线作为一个基本单元配置基于单端双回线电气量的一体化保护,主要包括一体化突变量选相元件、测量阻抗元件和跳合闸逻辑等内容的研究。针对理想换位同杆双回线典型故障特性分析,将六导线故障电气量分解为三相同向和异向故障相量,发现同向故障相量特征主要与故障涉及相别有关,而异向故障相量特征主要与两回线同名相故障状态是否对称有关,据此形成了故障选相和两回线状态不对称相判别依据,再结合特定异名相线间突变量关系选线和零同序电压电流突变量判断接地,从而形成完整的一体化突变量选相元件。利用相分量法对保护安装处到短路点的六导线电压电流方程分解,可推导得出涉及本线、邻线零序补偿系数的表征故障距离的一体化测量阻抗元件,针对单相接地故障和多相故障,分别形成6个单相线接地测量阻抗元件和12个异名相线间测量阻抗元件。将准三相运行等效为两点断线故障,借助MATLAB计算分析各准三相工况下主要运行指标,并提出一种以导线最大过载率、负序电流不平衡度和极限传输功率为参考项的综合评价指标,作为准三相方式选择与转换的依据。为实现准三相运行,在切除故障电气特性基础上,充分发挥同杆并架线路的优势减少切除线路和重合闸,形成同杆双回线一体化跳合闸策略作为一体化保护的执行元件。
[Abstract]:With the increase of power demand, the same pole and parallel transmission line has been widely used in many countries and regions because of its narrow exit corridor, large transmission capacity and high reliability of power supply. In China, the number of 220kV and above voltage grade double circuit lines is increasing day by day, and most of them are full-length parallel pole. As the first choice of the main protection for the same-pole double circuit line, the reliability of the split-phase vertical differential protection is restricted by the longitudinal communication channel, so it is urgent to use the protection based on the single-terminal electric volume as the main backup. When the traditional distance protection is applied to the double circuit line of the same rod, the phase-selecting element and the measuring impedance element are affected by the cross-line fault and the mutual inductance between the lines, so it is easy to misoperate or refuse to move. This paper presents an integrated protection based on single-ended and double-circuit electric volume with the same pole double circuit as a basic unit, which mainly includes the research of the integrated sudden phase selection element, the measuring impedance element and the trip-closing logic and so on. Based on the analysis of typical fault characteristics of ideal transposition double circuit line, the electric volume of six-wire fault is decomposed into three identical and different direction fault phasor, and it is found that the characteristic of the same direction fault phasor is mainly related to the difference of fault involved. However, the phasor characteristics of different faults are mainly related to the symmetry of the fault state of the same phase of the two circuit lines, thus forming the basis for distinguishing the fault phase selection and the asymmetrical state of the two circuit lines. Combined with the relationship between the abrupt variables of the special synonym lines and the zero synchronous voltage and current sudden variables, the earthing can be judged, thus forming a complete integrated phase selecting element of the sudden variables. The phase component method is used to decompose the six-wire voltage and current equation from the protection installation point to the short circuit point, and the integrated measuring impedance element involving the zero sequence compensation coefficient of the local line and the adjacent line is derived, which indicates the fault distance. Aiming at single-phase grounding fault and multi-phase fault, six single-phase line grounding impedance elements and 12 heterogeneous phase line measurement impedance elements are formed respectively. The quasi-three-phase operation is equivalent to two-point broken line fault, the main operating indexes under each quasi-three-phase operating condition are calculated and analyzed by means of MATLAB, and a kind of maximum over-loading rate of conductor is put forward. The negative sequence current imbalance and the limit transmission power are the comprehensive evaluation indexes of the reference term, which can be used as the basis for the selection and conversion of quasi-three-phase mode. In order to realize the quasi-three-phase operation, on the basis of the electrical characteristics of the cut-off fault, the advantages of the same-pole parallel line are fully utilized to reduce the cut-off line and reclosure, and the integrated trip-off strategy of the same-pole double-circuit line is formed as the executive element of the integrated protection.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM773

【参考文献】