Active power filter for compensating power harmonics

Control of an active power filter to compensate for current harmonics in nonlinear loads and to reduce the connected power.

Project goal

In numerous industrial applications, loads are powered from the three-phase grid via uncontrolled diode bridges. These nonlinear loads draw a pulsating current with a high harmonic content from the grid. The harmonic currents result in power components that oscillate back and forth between the grid and the load without contributing significantly to energy transfer. Nevertheless, the grid connection, wiring, and fuses must be designed to handle the resulting increase in the root-mean-square (RMS) value of the grid current and the correspondingly higher apparent power.

An active power filter, implemented as a pulse-width-modulated inverter, offers the possibility of specifically compensating for these harmonics. Connected in parallel with the load, it injects the unwanted components of the load current in antiphase, so that, ideally, the grid need only supply the sinusoidal fundamental current. In this way, the required grid connection power for the application can be reduced without changing the load itself.

As part of this project, a control architecture for the active power filter will therefore be developed that combines dynamic current control for the selective compensation of harmonics with a superimposed intermediate circuit control.

Project duration

July 2026 to September 2027