文献类型：期刊文献

英文题名：Analysis on the harmonics and inter-harmonics of a variable speed wind turbine

作者：Zhang, Yanchi[1];Xie, Da[2];Yu, Jinshou[1];Chu, Haoxiang[2]

机构：[1]E China Univ Sci & Technol, Dept Automat, Shanghai 200237, Peoples R China;[2]Shanghai Jiao Tong Univ, Dept Elect Engn, Shanghai 200240, Peoples R China

年份：2015

卷号：7

期号：4

外文期刊名：JOURNAL OF RENEWABLE AND SUSTAINABLE ENERGY

收录：;EI(收录号：20153501207217);WOS:【SCI-EXPANDED(收录号:WOS:000360655500051)】；

基金：This work was funded by the National Natural Science Foundation of China (Grant No. 51277119).This work was supported by Shanghai education commission, science and technology innovation fund project (Grant No. 10Y217).

语种：英文

外文关键词：Asynchronous generators - Spectrum analysis - Harmonic analysis - Electric utilities - Electric fault currents - Fast Fourier transforms

摘要：Due to the increasing number of wind turbines directly connected to the electric utility grid, harmonics and inter-harmonics of variable speed wind turbines are capturing the attention of electrical power engineers. This paper develops a framework of doubly fed induction generator (DFIG)-based wind turbines for analyzing the harmonics and inter-harmonics at low frequencies due to wind turbines operated in different conditions. Two methods have been proposed to analyze harmonics and inter-harmonics related to the quantities such as excitation current, DC voltage, and AC. In order to detect the precise frequencies and amplitudes of the harmonics at low frequency, a modified S-transform measurement method with adjustable Gaussian window regulator is proposed. The time-frequency resolution of the S-transform can be changed when measurement accuracy enhancement is needed. In contrast to the conventional fast Fourier transform, the improved S-transform method considers the variations of frequencies and amplitudes of excitation current harmonics. Thus, the overall measurement performance is considerably enhanced with higher frequency resolution. Results from both simulation and experiment are presented to illustrate the merits of the modified S-transform measuring method in spectral analysis of harmonics and inter-harmonics. The experimental results from a practical 1.25MW DFIG-based wind turbine under different operation conditions reveal that the characteristic frequencies with maximum harmonic currents change smoothly with the increase of the output active power. (C) 2015 AIP Publishing LLC.