基于稀疏复原算法的风电并网电压闪变包络线提取

闪变包络线检测是分析电压波动与闪变的关键。IEC推荐的平方检测法在闪变低频段的包络线提取误差较大,不适合风力发电并网产生的电压闪变包络线提取。文中针对风电并网引起的电压闪变问题,提出了基于稀疏复原算法的闪变包络线提取方法。以电压闪变信号的极值点作为观测序列,根据闪变包络线低频段较平稳的变化特性,构造变频宽的离散余弦变换基,利用正交匹配追踪算法还原出最佳闪变包络线。通过对单一频率闪变、复合频率闪变、基波频率变动、谐波及噪声影响的电压闪变信号进行分析,表明了该算法提取闪变包络线的准确性。最后,通过对张北柔直电网中新能源风电场实测的电压波动信号进行分析,进一步验证了所提算法提取风电并网引起的电压闪变包络线的可行性与有效性。

Envelope Tracking of Voltage Flicker Caused by Wind Power Integration Based on Sparse Recovery Algorithm

Flicker envelope tracking is the key to analyze voltage fluctuation and flicker. The square detection method recommended by IEC has a large error in the low-frequency range of voltage flicker. It is not suitable for the envelope tracking of voltage flicker caused by wind power integration. Aiming at the problem of voltage flicker caused by wind power integration, this paper proposes an envelope tracking method of voltage flicker based on the sparse recovery algorithm. The extreme points of the voltage flicker signal are taken as the observation sequence, and a discrete cosine transform base with varied band width is constructed according to the smoother variation characteristics of the flicker envelope at the low-frequency band. Then the orthogonal matching pursuit algorithm is used to recover the optimal flicker envelope. By analyzing several types of voltage flicker signal with single-frequency flicker, multi-frequency flicker, fundamental frequency variation, harmonics and noise, the accuracy of the proposed algorithm to track the flicker envelope is demonstrated. Finally, the measured voltage fluctuation signals of the wind farm in Zhangbei flexible DC grid of China are analyzed, which verifies the feasibility and effectiveness of the proposed algorithm for tracking the voltage flicker envelope caused by wind power integration.