Harmonic compensation in distribution system using 3-level NPC VSI based hybrid filter

This paper uses the combined topology of series active filter and shunt passive filter. The passive filter commonly eliminates the current harmonics produced by the load, but it has some limitations which results in operation not up to mark. On the other hand series active filter improve the filtering characteristics of the passive filter as well as compensate voltage harmonics produced by the load appears on the source side (source currents), which improves the performance of the power system. Also, it reduces rating of active filter which results in practical and economical system. The series active filter is realized using a neutral-point clamped inverter topology with appropriate control scheme based on instantaneous p-q theory. An extensive digital simulation has been carried out using MATLAB to show the satisfactory performance of the hybrid filter.