Power Quality Application Examples | Semikron Danfoss
Block diagram of an active power filter
Active line filters (power quality management)
Operators of industrial facilities and rail networks, in particular, use active line filters with IGBT modules to meet the requirements of energy suppliers in terms of low mains feedback. The applications cover a wide range of outputs, from 1 kVA to several MW with parallel power converters. Active line filters are controlled power sources that can feed current into the network with any amplitude, frequency or phasing to compensate for harmonics and reactive power caused by the load. Their topology is that of an inverter with DC bus voltage which is connected to the network via a filter (see figure 2).
Constant comparison of the actual value of the current in the network against the target value determines the energy that must be fed from the DC link capacitors via the inverter into the network, separately for each phase. In order to achieve good control dynamics, the highest possible pulse frequencies must be used.
