【作者】 匡军；

【导师】 段建东；

【作者基本信息】 西安理工大学 ， 电力系统及其自动化， 2010， 硕士

【摘要】 现代电力系统呈现大容量、远距离、高电压、联合电网的发展趋势,对电网运行的稳定性要求更高。快速切除故障是确保电力系统稳定运行的有效措施之一。暂态量保护利用故障分量中的高频暂态分量来进行故障的判别、实现保护功能,具有响应快、准确性高等优点,而且不受过渡电阻、系统振荡、TA饱和等因素的影响。因此,暂态量保护可以改善继电保护装置的性能、解决工频量保护固有的弊端,成为未来继电保护的发展方向之一输电线路故障时产生的高频分量在经过线路边界后会遭受大量的衰减和反射作用,因此在保护安装处检测到的区内外故障分量存在差异,利用此差异可实现区内外故障的识别。本文在分析输电线路边界频率特性的基础上,提出两种基于故障暂态分量的超高压输电线路保护算法。其一为利用改进递归小波变换相位信息的暂态保护算法：采用改进递归小波变换提取故障电流信号中的暂态分量,利用小波变换后的相位信息来测量故障信号的平均频率,通过区内外故障暂态信号的平均频率差异来识别故障。其二为利用希尔伯特-黄变换的暂态保护算法：采用希尔伯特-黄变换方法对故障电流信号进行处理,得到信号高频分量的Hilbert谱,通过比较故障发生时刻的瞬时频率大小来判别区内外故障。通过电磁暂态仿真软件PSCAD/EMTDC搭建了实际的500kV超高压输电线路模型,对不同故障距离、不同故障类型、不同故障过渡电阻、不同故障初始角、不同边界等多种故障情况进行了大量的仿真,并利用MATLAB处理仿真数据,对所提算法进行测试实验,实验结果表明本文所提出的两种暂态保护算法具有可行性。更多还原

【Abstract】 Modern power system develops the trend of large capacity, long distance, high voltage and interconnected grid, which demands higher transient stability for power system. Clearing the faults rapidly is an effective method to ensure stable operation. Transient Based Protection utilize high-frequency components of fault transient to carry out discrimination, achieve their protective function, with fast response, high accuracy advantages, but also is insensitive to the transition resistance, the system oscillation, TA saturation and other factors. Therefore. Transient Based Protection can improve the performance of protective relaying devices, to solve the inherent defects of the frequency protection, become one of the development directions of power system protective relaying.Transmission line fault-generated high frequency components through the line boundary can suffer a large number of attenuation and reflection, so the detection internal and external fault component are differences, this difference can be realized the fault identification. On the basis of the frequency characteristics of line boundary, this paper was proposed two protection algorithms for EHV transmission lines based on fault transient components. The first is based on improved recursive wavelet transform (IRWT) phase information of the transient protection algorithms:IRWT is used to extract desirable frequency components of fault-induced transient current signals, according the difference of the average frequency of the extracted signals which measured by their phase information, an internal or external fault can be distinguished. The second is a transient protection algorithm based Hilbert’s-Huang Transform:Hilbert-Huang Transform method process fault current signal to achieve Hilbert spectrum of the high-frequency components, according to compare the size of instantaneous frequency at the fault-occurred time to determine the internal and external fault.A simulation model of 500 kV extremely high voltage transmission systems are established on the platform of PSCAD/EMTDC. A lot of simulations about different fault conditions such as fault location, fault resistance, fault type, fault inception angle and different更多还原