Active filters are power electronic devices connected in parallel with the load to be compensated. The device can be thought of as a controlled current source, which provides any kind of current waveform in real time. When connected in parallel with the nonlinear load, its harmonic currents are compensated and the network is loaded with fundamental current only. The control system monitors the relevant parameters of the network and is capable of detecting and instantaneously reacting to any disturbance in the load current.

Active filters are power electronic devices connected in parallel with the load to be compensated. The device can be thought of as a controlled current source, which provides any kind of current waveform in real time. When connected in parallel with the nonlinear load, its harmonic currents are compensated and the network is loaded with fundamental current only. The control system monitors the relevant parameters of the network and is capable of detecting and instantaneously reacting to any disturbance in the load current.