Advanced power electronics for reducing mains pollution - Active power filters and optimized utility interfaces

Rapid advances in turn-off semiconductor elements offer new opportunities for reactive power compensation and reduction of harmonics in energy supply systems. Non-linear consumers and also solid state power electronic equipment like diode rectifiers and thyristor converters disturb the utility voltage waveform by injecting harmonic currents into the utility grid. Their need of reactive power results in higher line currents and thereby in an increase of the rated power of the supply system. Active power filters can be used to compensate the harmonic currents, to balance unbalanced systems and to provide reactive power to the load with small storage elements. Optimized utility interfaces are controlled to ensure sinusoidal input currents of the load with unity power factor. Both, the investigated active power filter as well as the optimized utility interface are based on a four-quadrant switch-mode voltage source inverter.