变压器涌流问题的研究

【作者】 贺勋；

【导师】 束洪春；

【作者基本信息】 昆明理工大学 ， 电力系统及其自动化， 2006， 硕士

【摘要】 变压器主保护选择差动在原理上存在不足,带来的问题就是如何准确鉴别励磁涌流与内部故障,这也是目前变压器保护的难点。 本文研究了变压器产生励磁涌流的机理,分析了几种鉴别励磁涌流方法的优缺点和利用二次谐波电流制动励磁涌流的原理及其存在的问题。在对电压突变量原理进行分析的基础上,提出了基于电压突变量的励磁涌流辅助判据,并利用MATLAB软件中的PSB对励磁涌流、内部故障及励磁涌流伴随内部故障进行仿真。通过仿真得到的结果表明,这种方法简单有效,易于实现。 本文通过对变压器和应涌流的产生机理、影响因素及其危害原因的分析,讨论和应涌流对变压器保护的影响,并在此基础上提出了相应的防范措施。 论文最后对变压器外部故障切除后电压恢复的暂态过程进行了分析,指出:电压恢复性涌流可能导致变压器差动保护及电流保护误动作。更多还原

【Abstract】 How to discriminate between internal fault and magnetizing inrush current is the difficulty of transformer protection when apply differential relay.In this thesis, the mechanism of inrush current occurring in transformer is well researched, the advantages and disadvantages of several methods for checking inrush current are discussed, the theory of applying second harmonic current to lock the tripping operation of the circuit breaker during inrush current and its problem are analyzed. The principle of Au is analyzed in this thesis, and a new method to discriminate between internal fault and magnetizing inrush based onAu is bring forward in this paper. In this article, the simulation of inrush, internal fault and inrush which internal fault occur on at the same time and exterior fault is done by using PSB of MATLAB. The result of these simulations demonstrates that these two methods are easy, effective, and adapted to practical application.Based on the analysis of sympathetic inrush in operating transformers, the principle and characteristics of sympathetic inrush and influencing factors are studied. Then the influence on transformer protection caused by sympathetic inrush are discussed. Finally, several countermeasure to sympathetic inrush are proposed.The transient induced by the isolation of the external faults is analysised at last in this paper. It is pointed out the transformer differential protection and the current protection possibly maloperates due to the recovery surge.更多还原