Line-voltage-sensorless active power filter for reactive power compensation

A line-voltage-sensorless three-phase active power filter is presented, and a current controller with fast dynamics for an active power filter is desc ribed, along with line synchronisation for an active power filter! which do es not require any additional hardware. The line synchronisation can be pro perly operated under line-voltage distortion or notching and line-frequency variation. Reactive power compensation is achieved without computing the r eactive current of the load. Current compensation is done in the time domai n allowing a fast time response. The DC voltage-control loop keeps the volt age across the DC capacitor constant. Unity power-factor control by an acti ve power filter is described. All control functions are implemented in soft ware using a single-chip microcontroller, thus simplifying the control circ uit. It is shown, via experimental results, that the proposed controller gi ves a good performance in the line-voltage-sensorless active power filter.