无锁相环d-q谐波电流检测法的实现

电力有源滤波器是补偿电力系统中谐波及无功功率的重要装置，其关键环节是实时准确的检测出谐波电流。基于d-q坐标变换的谐波电流检测方法不受电压影响，并能应用于负荷电流不对称的情况。文中介绍了d-q坐标变换的谐波电流检测的基本原理，在此基础上提出了一种无锁相环的实现方法。分析指出，d-q变换过程中的频率偏差对检测结果不构成影响。该方法用PSCAD／EMTDC软件进行了仿真，并应用于电力有源滤波器样机。实验结果表明，该检测方法是准确可行的。

REALIZATION OF HARMONIC CURRENT DETECTION OF d-q TRANSFORMATION WITHOUT PHASE LOCK LOOP

The Active Power Filter (APF) is an important equipment to compensate harmonic and reactive current in systems, the key problem in APF is to detect the harmonic current accurately in real-time mode. The harmonic current detecting method based on d-q coordinate transformation is not influenced by voltage and can be applied to unbalanced load current. The basic principle of d-q harmonic current detection is presented and on this basis an implementation method without phase lock loop (PLL) is put forward. In the d-q transformation process the detection results will not be influenced by frequency offset. The presented method is simulated by PSCAD/EMTDC software and tested by a prototype of APF. The results from simulation and tests prove that the presented method is accurate and feasible.