级联形态梯度变换及其在继电保护中的应用

介绍了现在应用已较成熟的灰值腐蚀和灰值膨胀运算,由此引出多分辨形态学梯度变换(MMG)的定义;进而在其基础上提出了一种新型的级联多分辨形态梯度变换(SMMG)的概念,SMMG具有很强的奇异信号检测和波形识别能力,作为一种特征提取工具,SMMG能感受并增强信号波形上的微小变化、反映突变的大小.和其它形态学算子一样,它具有SMMG具有表达直观、滤波器设计简单、数据窗短、计算速度快以及变换结果易于识别、对硬件没有过高的要求等优点,因此在继电保护的信号处理中具有良好的应用潜力和实用价值,在现有的微机保护装置中可以直接采用.文中最后给出了其在电力系统继电保护中应用的2个实例,EMTP仿真研究表明:文中提出的相继速动判据具有更高的灵敏度;所提出的基于SMMG的微机线路保护的选相元件能在8ms内正确地识别几乎所有故障情况的故障相别.由SMMG构成的保护元件灵敏度很高,在电力系统高速及超高速保护方面有良好的应用前景及较大的实用价值.

SERIES MULTI-RESOLUTION MORPHOLOGICAL GRADIENT AND APPLICATIONS IN PROTECTION RELAYING

The concepts of the morphological erosion, dilation and Multi-resolution Morphological Gradient (MMG) are introduced in this paper. Using these concepts, a novel technique, Series Multi-resolution Morphological Gradient (SMMG) transform is proposed in this paper. As an outstanding feature extractor for the raw signals, SMMG is able to detect faint signal changes and reflect the amplitude of signal disturbances. Like other morphological operations, the SMMG filter is a fast-calculating algorithm and has no special requirement for hardware, therefore, the algorithm can be easily implemented in digital relay. SMMG has a great potential for improving the performance of protection relays of power system. Two applications of SMMG in protection relay of power system are presented in the paper. The EMTP simulation result shows that the SMMG based approach to accelerated trip of power transmission line has a high sensitivity and the SMMG based phase selector can successfully identify the fault phases in less than 8 milliseconds. The SMMG based relays have practical value and prospects in the field of high-speed and ultra-high-speed protection.