改进dq变换法及在STATCOM中应用

针对传统dq变换法在检测电网三相不对称分量时存在的一些缺陷,提出一种新的检测方法,将单相电压通过一个微分器得到与该相电压正交的微分量,然后利用二者的正交关系直接通过数学关系求解出同步旋转角.该方法不仅适用于负载不对称系统,也适用于电源电压不对称系统.在检测过程中,不需要采用锁相环(PLL)电路获得同步旋转角,消除了PLL延时带来的影响,也不需要对三相电流进行移相,解决了移相带来的误差.将该检测方法应用于静止同步补偿器(STATCOM)控制器后,能有效降低接入点电压的不平衡度.仿真分析和实验结果表明所提出的方法在检测电流正序、负序分量时具有精度高、实时性强的特点,更适合于STATCOM的应用.

Improved dq transformation method and its application in STATCOM

As the traditional dq transformation method is not sufficient in the detection of 3 -phase unbalanced components,a new detection method is presented,in which a single -phase voltage is input to a differentiator to get an orthogonal differential,then use the orthogonal relation to achieve the synchronous rotation angle through math solution. The new detection method is suitable for both unbalanced load and unbalanced source systems. Because it does not use PLL circuit to obtain synchronous rotation angle, the influence of PLL time delay is removed. Because the phase shifting of 3 -phase currents is not necessary,its error is eliminated. The unbalance degree of input voltage is effectively reduced when applying this method to STATCOM. Simulative analysis and experimental results indicate that,the proposed method has high precision and rapid response in detecting the positive and negative sequence components of currents,more suitable for STATCOM.