母线采样值差动保护判据的研究

发布时间：2018-04-29 03:37

本文选题：母线故障 + 采样值差动保护　；参考：《南京理工大学》2017年硕士论文

【摘要】：采样值差动保护因其动作速度快,具有很强的抗扰动和容错能力,已渐渐发展为数字式母线差动保护的主流原理和标准配置。但由于母线区外故障时电流互感器发生饱和,采样值差动保护还需要与抗CT饱和识别判据配合。本文针对母线差动保护的这个焦点问题,研究了电流互感器的饱和机理,分析了其饱和特性;对目前国内外已有的母线差动保护抗CT饱和方法进行了总结,并比较了它们各自的优缺点和性能。阐述了采样值差动保护的基本原理,对数据窗大小的选取,R和S的合理选择、制动系数的整定进行了分析,并对模糊区的大小进行了讨论。在此基础上提出了一种改进的母线采样值差动保护判据,该判据包括突变量启动元件、第一CT饱和周波判据、基于CT线性传变区的采样值差动保护判据。判据利用CT饱和时的波形特征,以制动电流的变化率来检测CT线性传变区的起点,并根据差动电流与制动电流的比例关系确定CT线性传变区的终点。该判据与新型制动量差动判据相配合,构成完整的母线采样值差动保护。在PSCAD平台中建立故障仿真模型,最后通过在MATLAB平台中编写算法仿真试验了在各种故障类型下此差动保护方案的动作情况,探究了故障初始相角差、故障转换时间、频率偏移、采样频率对此方案的影响,仿真结果证明了基于CT线性区的母线差动保护方案能正确区分区内外故障,在区内故障时快速动作,区外故障时可靠不动作,发生区外转区内的转换性故障时能迅速可靠动作。
[Abstract]:The sampled-value differential protection has become the mainstream principle and standard configuration of digital busbar differential protection because of its high speed and strong anti-disturbance and fault-tolerant ability. However, due to the saturation of the current transformer outside the busbar fault, the sampling value differential protection needs to be matched with the anti-CT saturation identification criterion. Aiming at this focus of busbar differential protection, this paper studies the saturation mechanism of current transformer, analyzes its saturation characteristics, summarizes the existing anti-CT saturation methods of busbar differential protection at home and abroad. Their advantages, disadvantages and performances are compared. The basic principle of sampled-value differential protection is expounded. The reasonable selection of data window size R and S and the setting of braking coefficient are analyzed and the size of fuzzy region is discussed. On this basis, an improved bus sampling value differential protection criterion is proposed. The criterion includes abrupt start element, the first CT saturated Zhou Bo criterion, and the sampling value differential protection criterion based on the CT linear transmission region. The criterion uses the waveform characteristics of CT saturation to detect the starting point of CT linear transmission region by the change rate of braking current, and determines the terminal point of CT linear transmission region according to the ratio of differential current and braking current. This criterion is compatible with the new braking differential criterion and forms a complete busbar sampling value differential protection. The fault simulation model is established in PSCAD platform. Finally, the operation of the differential protection scheme under various fault types is tested by programming algorithm in MATLAB platform, and the initial phase angle difference, fault conversion time and frequency deviation are explored. The effect of sampling frequency on this scheme is proved by the simulation results. The bus differential protection scheme based on CT linear region can correctly distinguish the fault inside and outside the area, and can act quickly in the fault area and reliably not in the fault outside the area. It can act quickly and reliably when the transition fault occurs in the outer turning area.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM773

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