两相静止坐标系下消除不对称和谐波影响的同步信号提取方法

Synchronization Signal Extraction Method in Two-Phase Stationary Reference Frame for Eliminating Imbalance and Harmonic Effects

三相并网变流器可以在同步旋转坐标系下,也可以在两相静止坐标系下进行控制。无论在哪一种坐标系下进行控制,都需要能够快速准确地提取出电网同步信号。为了满足两相静止坐标系下变流器的控制需求,文中将正弦幅值积分器应用于两相静止坐标系下的同步信号提取。通过对在不对称和含有谐波情况下的输入电压进行矢量描述,提出采用多通道正弦幅值积分器的同步信号检测方法,可以消除负序分量和谐波分量的影响,而且无需进行正负序分离就可以直接得到正序分量和负序分量的幅值和相位信息。文中建立了多通道正弦幅值积分器同步信号提取方法的数学模型,揭示了同步信号提取的机理并讨论了反馈参数的选取原则。通过构造频率自适应算法,克服了电源频率变化对同步信号提取的影响。理论分析和实验结果都表明所提出的同步信号提取方法可以在电源频率变化、不对称以及含有谐波的情况下快速准确出提取出正负序分量的幅值和相位信号。

The three-phase grid-tied converters can be controlled either in the rotational reference frame or in the stationary reference frame. The grid synchronization signal needs to be extracted fast and accurately when either reference frame is employed. The sinusoidal amplitude integrator is employed to extract the grid synchronization signal in two-phase stationary reference frame for the control of three-phase grid-tied converters in the same reference frame in this paper. Through the vector description of three-phase voltage with harmonics and imbalance components, the grid synchronization method with multiple sinusoidal integrators is proposed. The presented method can eliminate the effects of harmonics and imbalance and extract the amplitude and phase information of the positivesequence and negative-sequence components directly without the positive and negative sequence decomposition. The mathematical model is set up to show the mechanism of the presented synchronization method and determine the feedback parameter. A frequency adaptive method is designed to overcome the grid frequency variation. The theoretical and experimental results indicate that the presented synchronization method has the property of separate the positive-sequence and negative-sequence components for imbalance grid voltage with harmonics even under grid frequency variation condition.