Hybrid active filter for power factor correction and harmonics elimination in industrial networks

In modern industrial processes, the number of nonlinear loads - known to be a major source of current harmonics - is constantly growing. At the same time, the number of reactive-power compensators operating in these networks is growing too. Though the compensators are not the source of harmonic distortions, they may cause high amplifications of harmonics by creating resonance conditions. This can cause malfunctions or even loss of equipment. This paper presents a hybrid compensator as a combination of three-phase shunt LC passive compensator connected in series with a small-rating active compensator. The main objective of the presented hybrid capacitor system is to compensate reactive power. The active part of the filter is used to improve the filtering performance of the passive part and prevent the resonance amplifications of current harmonics. As a result, no harmonic resonance occurs under any system condition. The effectiveness of the hybrid compensator is demonstrated on a realistic industrial-network model by means of simulations.