Focusing on higher computation cost and lack of real-time detection for all techniques based on traditional S-transform to identify power quality disturbances
a real-time approach combining fast S-transform with least squares support vector machine is proposed. The standard deviation of module coefficients
maximum module coefficient of each frequency band
and module coefficient corresponding to the rated frequency are extracted from the one-dimensional vector of the fast S-transform of the original power quality signals as features
and the least squares support vector machine based on optimized parameters and the minimum output coding is used to classify and identify the voltage swell
voltage sag
voltage interruption
spike
transient oscillation and harmonic waves. Compared with the traditional approach based on S-transform
the proposed approach reduces the tasks in both extracting features and training of the support vector machine classifier due to fewer training samples. The longer the duration of the voltage disturbance signal
the higher the saving efficiency. To the same accuracy
for the disturbance signal with a length of 1 024 points
processing time can be saved by 99%. The classification accuracy of this approach gets up to 98% with higher anti-interference ability.
ZHAN Yong, CHENG Haozhong, DING Yifeng, et al. S-transform-based classification of power quality disturbance signals by support vector machines [J]. Proceedings of the CSEE, 2005,24(4):51-56.
LI Lin,YANG Honggeng. Short duration power quality disturbance signal classification method based on two-dimensional discrete static wavelet transform [J]. Automation of Electric Power Systems, 2007,31(10):21-26.
HE Wei, YANG Honggeng. Disturbance classification based on second generation wavelet transform and discrete hidden Markov models [J]. Transactions of China Electrotechnical Society, 2007,22(5):146-152.
WANG Chengshan, WANG Jidong. Classification method of power quality disturbance based on wavelet packet decomposition [J]. Power System Technology, 2004,28(15):78-82.
QIN Yinglin, TIAN Lijun, CHANG Xuefei. Classification of power quality disturbance based on wavelet energy distribution and neural network [J]. Electric Power Automation Equipment, 2009,29(7):64-66.
SANTOSO S, POWERS E J, GRADY W M. Power quality disturbance identification using wavelet transforms and artificial neural networks [C]∥Proceedings of IEEE ICHQP Ⅶ. Piscataway,NJ,USA:IEEE, 1996:615-618.
LIU Shouliang, XIAO Xianyong, YANG Honggeng. Classification of short duration power quality disturbance based on module time-frequency matrixes similarity by S-transform [J]. Power System Technology, 2006,30(5):67-71.
XIAO Xianyong, XU Fangwei, YANG Honggeng. Short duration disturbance classifying based on S-transform maximum similarity [J]. International Journal of Electrical Power and Energy Systems, 2009,31(7):374-378.
黄南天,徐殿国,刘晓胜. 基于 S 变换与 SVM 的电能质量复合扰动识别 [J]. 电工技术学报, 2011,26(10):23-30.
HUANG Nantian, XU Dianguo, LIU Xiaosheng. Identification of power quality complex disturbances based on S-transform and SVM [J]. Transactions of China Electrotechnical Society, 2011,26(10):23-30.
ZHAO Fengzhan, YANG Rengang. Power quality disturbances classification based on S-transform and time domain analysis [J]. Power System Technology, 2006,30(15):90-94.
YANG Honggeng, LIU Shouliang, XIAO Xianyong, et al. S-transform-based expert system for classification of voltage dips [J]. Proceedings of the CSEE, 2007,27(1):98-104.
SHEN Yue, LIU Guohai, LIU Hui. Classification identification of power quality disturbances based on modified S-transform and Bayes relevance vector machine [J]. Control and Decision, 2011,26(4):587-591.
BROWN R A, LAUZON L M, FRAYNE R. A general description of linear time-frequency transforms and formulation of a fast,invertible transform that samples the continuous S-transform spectrum nonredundantly [J]. IEEE Trans on Signal Processing, 2010,58(1):281-290.
YANG Yanxi, LIU Ding. Short-term load forecasting based on wavelet transform and least square support vector machine [J]. Power System Technology, 2005,29(13):60-64.
YI Jiliang, PENG Jianchun, LUO An, et al. Power quality signal denoising using modified S-transform [J]. Chinese Journal of Scientific Instrument, 2010,31(1):32-37.
GAO Jinghuai, MAN Weishi, CHEN Shumin. Recognition of signal from colored noise background in generalized S-transform domain [J]. Chinese Journal of Geophysics, 2004,22(5):869-875.
PINNEGAR C R, MANSIHA L. Time-local spectral analysis for non-stationary time series: the S-transform for noise signal [J]. Fluctuation and Noise Letters, 2003,3(3):357-364.
MAN Weishi, GAO Jinghuai. Statistical denoising of signals in the S-transform domain [J]. Computers Geosciences, 2009,35(6):1079-1086.