平行双回线单相接地故障距离保护研究

发布时间：2018-07-11 12:37

本文选题：双回输电线 + 单相接地故障　；参考：《华北电力大学(北京)》2014年硕士论文

【摘要】：同杆并架双回输电线在超、特高压工程中的应用日益广泛。当前实际运行中,平行双回输电线距离保护的效果受双回线零序互感的影响较大,不能满足电力系统运行的需求。因此研究新的距离保护算法,提高平行双回线距离保护的性能,具有十分重要的理论和现实意义。本文以一个平行双回线双端输电系统为研究对象,建立平行双回线单相接地故障的系统零序网络图。研究得出双回输电线的零序电流比值K是一个与系统运行方式和故障点位置密切相关的变量。零序电流比值K随故障距离D的变化是单调递增的凹曲线,而且系统零序阻抗越小,曲线的曲率越大。当故障距离变化时,平行双回输电线的零序电流比值K近似是一个实数。故障距离小于线路长度85%时,K的值很小,并且随着故障距离的改变变化不大；当故障距离超过线路长度85%时,K的值随着故障距离的改变变化很大。当线路末端故障时,K为1。提出了一种仅利用单回输电线单侧电气量的单相接地故障距离保护新算法。以不同系统运行方式下,距离保护Ⅰ段保护范围末端(线路85%)处最大的零序电流比值K作为整定值Kset,用Kset和本线路零序电流的乘积表示相邻线路的零序电流,从而得出了针对单相接地故障仅利用单回输电线单侧电气量的距离保护新算法。通过仿真表明,当发生金属性接地故障时,新算法在区内故障时能够可靠动作,区外故障时不会误动。无补偿传统距离保护算法的保护范围会缩短,会造成保护拒动。当接地电阻为15Ω时,新算法依然有良好的可靠性和准确性,两种传统算法在区外故障甚至是下级线路出口故障时,距离保护会误动作,发生超越。最后通过详细的仿真证明了新算法有良好的适用性。相邻线路故障时,新算法可靠性强,不会误动,两种传统算法均会发生误跳闸。新算法解决了传统算法在本线路区内故障时会导致相邻线路保护误动作的难题。系统运行方式变化时,新算法距离保护Ⅰ段的保护范围增大,但是线路末端故障时,距离保护Ⅰ段不会误动作。无补偿传统算法的保护范围缩小。在经故障电阻接地时,新算法的距离保护Ⅰ段动作特性良好,传统算法在区外故障时会误跳闸。负荷变化和线路分布电容对新算法的影响不大。
[Abstract]:The double-circuit transmission line with the same rod is widely used in ultra-high voltage engineering. In actual operation, the effect of distance protection of parallel double-circuit transmission lines is greatly affected by zero-sequence mutual inductance of double-circuit lines, which can not meet the needs of power system operation. Therefore, it is of great theoretical and practical significance to study a new distance protection algorithm to improve the performance of parallel double loop distance protection. In this paper, a parallel double-circuit double-terminal transmission system is taken as the research object, and the zero-sequence network diagram of the single-phase grounding fault of parallel double-circuit line is established. It is concluded that the zero-sequence current ratio K of double-circuit transmission lines is a variable closely related to the operation mode of the system and the location of the fault point. The variation of zero-sequence current ratio K with the fault distance D is a monotone increasing concave curve, and the smaller the zero-sequence impedance, the greater the curvature of the curve. When the fault distance changes, the zero-sequence current ratio K of parallel double-circuit transmission lines is approximately a real number. When the fault distance is less than the line length, the value of K is very small, and with the change of fault distance, the value of K changes greatly with the change of fault distance. When the end of the line fails, the K is 1. A new distance protection algorithm for single-phase grounding fault is proposed. Under different system operation modes, the maximum zero-sequence current ratio K at the end of the protection range (85%) of the distance protection section I is used as the setting value Kset. the product of Kset and the zero-sequence current of this line is used to express the zero-sequence current of adjacent lines. Thus, a new distance protection algorithm for single-phase grounding fault using only single side electric quantity of transmission line is obtained. The simulation results show that the new algorithm can operate reliably in the fault zone and not malfunction in the fault outside the area when the ground fault of gold attribute occurs. The protection range of uncompensated traditional distance protection algorithm will be shortened, which will cause protection rejection. When the grounding resistance is 15 惟, the new algorithm still has good reliability and accuracy. When the two traditional algorithms are out of the area fault or even the lower line outlet fault, the distance protection will misoperate and overstep. Finally, a detailed simulation shows that the new algorithm has good applicability. The new algorithm has strong reliability and no misoperation when the adjacent line is out of order, and the two traditional algorithms will be tripped by mistake. The new algorithm solves the problem that the traditional algorithm can lead to the misoperation of the adjacent line protection when the fault occurs in the local line area. When the operation mode of the system changes, the protection range of the distance protection section I of the new algorithm increases, but the distance protection section I will not be misoperated when the line end failure. The protection range of traditional uncompensated algorithm is reduced. When the fault resistance is grounded, the distance protection section I operation characteristic of the new algorithm is good, and the traditional algorithm will trip by mistake when the fault is out of the area. Load variation and line distribution capacitance have little effect on the new algorithm.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM773

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