计算出其他故障点信号数据压缩的赋范误差、平均误差和均方差,得到压缩比为20:1时随不同故障地点变化的赋范误差曲线如图6所示。50%处故障的暂态信号随不同压缩比变化的赋范误差曲线如图7所示。
由表1、图6和图7中压缩效果参数可知:
(1)GHM多小波及CL多小波对平稳信号(正弦信号)或暂态信号(故障信号)的数据压缩效果均比db4传统小波的好;
(2)采用Haar和平衡法预处理方法的CL4多小波的压缩效果均明显比采用GHM.init预处理方法的GHM多小波的压缩效果好;
(3)CL4多小波采用平衡预处理方法时,压缩效果总体上比Haar预处理方法的好一些。
5 结论
本文介绍和分析了CL多小波及其不同的预处理方法,采用保留分解后若干最大系数的数据压缩方法,对采用不同预处理方法的CL多小波在故障数据压缩中的效果与GHM多小波及传统db4小波进行了比较。综合各种压缩性能指标后认为,基于Haar法和平衡法的CL4多小波比基于GHM.init法的GHM多小波压缩效果优越,更适用于对电力系统信号的数据压缩。
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