| Summary: | Depending on detection points of harmonic current, the control strategies of parallel active power filter (PAPF) can be divided into two basic types. Load current detection is the simplest open loop control strategy, but the parallel resonant problem is an inherent defect of it. Source current detection forms an effective closed loop. However, a stability problem would be caused meanwhile. In this paper, firstly, typical system of PAPF was designed and analyzed, and different kinds of current control strategies were deeply discussed. In particular, a long time ignored problem (the amplification of the fundamental current after the compensation) associated with traditional source current detection was pointed out for the first time. Next, we proposed a new double-loop compound control strategy, which detects both the load current and the source current. Through the analysis of each part of the PAPF, the mathematics model of the system was put forward. Furthermore, we used this model to discuss the stability and compensation characteristics of the system, and found out the best working point through large amount of simulation. Finally, simulation results verified the validity of the proposed control strategy.
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