变压器保护算法和仿真研究

发布时间：2018-02-04 22:40

本文关键词： 变压器差动保护励磁涌流故障电流小波变换仿真　出处：《南京师范大学》2014年硕士论文　论文类型：学位论文

【摘要】：电力变压器作为现代电网中最重要的设备之一,承担着电压变换的重要任务。它的可靠运行是电网安全运行的必要条件。现代电力变压器电压等级高且价格昂贵,旦由于故障受到破坏,检修难度大,且耗时伤财。因此,现场对变压器保护的选择性、速动性、灵敏性和可靠性有了更高的要求。为了深入分析变压器在故障时的暂态情况,改进现有变压器保护中的不足,有必要研究变压器保护的算法和仿真模型。目前变压器差动保护的算法仍以比率制动特性原理为重点。采用差动保护作为变压器的主保护后,要解决内部故障电流和励磁涌流的识别问题。为了深入分析故障电流和励磁涌流的差异,本文首先分析了变压器的数学模型,并构建了变压器故障和励磁涌流仿真模型,仿真结果发现励磁涌流的波形有大量二次谐波和有明显间断角等特征。在励磁涌流识别的算法上,二次谐波制动原理在变压器保护设备中有着丰富的现场运行经验,然而在某些情况下存在变压器保护动作时间较长的问题。文中通过引入了小波变换的方法,能够解决二次谐波制动原理缺乏空间局部性的问题,并提高变压器保护的整体性能。嵌入式函数模块能够方便地编写程序代码,并且可以直接植入Simulink仿真建模中。论文基于MATLAB嵌入式函数模块建立了变压器差动保护的仿真模型,该模块能够区分区内和区外故障以及区分区内故障和励磁涌流。文中给出了仿真过程的参数整定计算方法及设计流程和逻辑动作方案。最后,针对变压器后备保护过电流保护,通过分析和研究某变电所变压器后备保护整定方案的缺陷,设计了将通信技术引入变压器后备保护方案,并且给出了后备保护方案原理图。该方案能够有效解决变压器后备保护的选择性和速动性的矛盾,同时该方案能够判断出故障位置。
[Abstract]:Power transformer is one of the most important equipments in modern power network. It is a necessary condition for the safe operation of power grid. Modern power transformers have high voltage grade and expensive price, so it is difficult to overhaul because of the failure. Therefore, the field has higher requirements for the selectivity, rapidity, sensitivity and reliability of transformer protection. It is necessary to study the algorithm and simulation model of transformer protection. At present, the algorithm of transformer differential protection is still focused on the principle of ratio braking characteristics. The differential protection is adopted as the main protection of transformer. In order to solve the problem of identifying internal fault current and inrush current, in order to analyze the difference between fault current and inrush current, this paper first analyzes the mathematical model of transformer. The simulation model of transformer fault and inrush current is constructed. The simulation results show that the waveform of inrush current has many characteristics such as second harmonic wave and obvious discontinuous angle. The second harmonic braking principle has rich field operation experience in transformer protection equipment. However, in some cases, the transformer protection operation time is longer. The method of wavelet transform is introduced in this paper. It can solve the problem that the second harmonic braking principle lacks space locality and improve the overall performance of transformer protection. Embedded function module can easily write program code. And can be directly implanted in the Simulink simulation modeling. Based on the MATLAB embedded function module, the paper establishes the transformer differential protection simulation model. The module can distinguish the fault in and out of the region and the inrush current in the region. The parameter setting calculation method, design flow and logic action scheme of the simulation process are given in this paper. Finally, aiming at the over-current protection of transformer backup protection, by analyzing and studying the shortcomings of the setting scheme of transformer backup protection in a substation, the paper designs a transformer backup protection scheme which introduces the communication technology to the transformer backup protection. The schematic diagram of the backup protection scheme is given, which can effectively solve the contradiction between the selectivity and the rapidity of the transformer backup protection, and at the same time, the scheme can judge the fault location.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM41

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