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电压凹陷是电能质量的重要问题之一,动态电压恢复器可有效抑制电压凹陷,要求检测算法动态响应速度快。瞬时dq变换法简单、易实现,在动态电压恢复器中应用较多,但低通滤波器降低了瞬时dq变换法的动态响应速度。针对该问题,分析了瞬时dq变换法动态响应过程特点,提出了卡尔曼滤波器校正的改进dq变换法。将动态过程的d轴分量分解为衰减分量和常分量,利用卡尔曼滤波器估计出常分量,并把该分量作为动态过程校正后的d轴分量。d轴变化量大于阈值时启动卡尔曼滤波器;衰减分量小于阈值时退出卡尔曼滤波器。在Matlab6.5中将该方法用于检测多种电压凹陷,结果表明,该方法比传统dq法具有更快的动态响应速度,满足动态电压恢复器的实时性要求。
The voltage sag is one of the important problems of power quality. The dynamic voltage restorer can effectively restrain the voltage sag and requires the dynamic response speed of the detection algorithm to be fast. The transient dq transform method is simple and easy to implement, and it is widely used in dynamic voltage restorer. However, the low-pass filter reduces the dynamic response speed of instantaneous dq transform. In response to this problem, the characteristics of dynamic response process of instantaneous dq transform are analyzed, and an improved dq transform method of Kalman filter correction is proposed. The d-axis component of the dynamic process is decomposed into the attenuation component and the constant component, the Kalman filter is used to estimate the constant component, and the component is taken as the d-axis component after dynamic process correction. The Kalman filter is activated when the d-axis variation is greater than the threshold and the Kalman filter exits when the attenuation component is less than the threshold. The method is used to detect a variety of voltage sags in Matlab6.5. The results show that this method has a faster dynamic response than the traditional dq method and meets the real-time requirements of the dynamic voltage restorer.