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 described, along with line synchronisation for an active power filter, which does not require any additional hardware. The line synchronisation can be properly operated under line-voltage distortion or notching and line-frequency variation. Reactive power compensation is achieved without computing the reactive current of the load. Current compensation is done in the time domain allowing a fast time response. The DC voltage-control loop keeps the voltage across the DC capacitor constant. Unity power-factor control by an active power filter is described. All control functions are implemented in software using a single-chip microcontroller, thus simplifying the control circuit. It is shown, via experimental results, that the proposed controller gives a good performance in the line-voltage-sensorless active power filter.