电网畸变下基于改进DSSOGI-FLL同步信号提取方法

为了满足在不对称、直流分量及谐波畸变等情况下同步信号的提取需求,三相电压需要准确地提取出电压信号的正负序分量、幅值和基波频率。基于DSOGI-FLL的方法可实现电压在不对称和畸变下同步信号的提取。但当电压跌落深大大、直流分量和多次谐波影响下,DSOGI-FLL方法无法实现同步信号的准确提取,使其追踪的波形波动比较大,并降低了追踪速度。文章对SOGI结构进行改进,使其在SOGI的基础上增加求差节点和自适应滤波器,提出了基于改进DSSOGI-FLL的同步信号提取方法,该方法在电压跌落深度大、直流分量和多次谐波影响下能够准确、快速提取出正负序分量、相位和频率等信息。仿真分析验证了改进方法的准确性和有效性。

Synchronization signal extraction method based on Improved DSSOGI-FLL in power grid distortion

With the rapid development of new energy such as wind power and photovoltaic power generation, three-phase grid connected converter has been widely applied. In order to meet the requirement of extracting synchronous signals in the condition of asymmetric, DC-offset and harmonics, the positive and negative sequence components, amplitude and fundamental frequency of the voltage signal need to be extracted accurately. The synchronization signal can be extracted under voltage asymmetry and distortion based on DSOGI-FLL. But when the unbalanced three-phase voltage is large, the DC component and the multiple harmonics are influenced by the DSOGI-FLL method, the accurate extraction of the synchronous signal can not be realized, and the waveform of the tracking is relatively large and the tracking speed is reduced. In this paper, the structure of SOGI is improved, and the difference node and adaptive filter are added on the basis of SOGI, and the method of synchronous signal extraction based on improved DSSOGI-FLL is proposed. In the case of large imbalance, DC-offet and multiple harmonics, this method can eliminate these effects well, and can accurately and quickly extract the positive and negative sequence components, phase and frequency information. The accuracy and effectiveness of the improved DSSOGI-FLL method is verified by simulation analysis.