Influence of the load characteristics and the line impedance on the stability of an active power filter

In this study, the authors try to show that a parallel active power filter has a significant influence on the behaviour of a load connected to an impedant network. Moreover, they claim that the nature of the load cannot be ignored and that even a very simple model shows that instabilities can occur with any type of control because the filter will necessarily have at least one pole. An experimentation with different types of loads confirms the stability and precision problems. In some cases a series inductance can improve the result in practice, though it cannot be considered as a universal solution. The main conclusion is that the load characteristics cannot be left aside during the design process of a controller. To overcome these difficulties, it would certainly be fruitful to consider a control strategy that ignores the model of the load as a sliding mode control for example.<>