Simulation study of an active DC filter using frequency-domain control system

Frequency-response analyses and digital time-domain simulations are presented in this paper for a frequency-domain approach to the control of an active DC filter for an HVDC power network. This is one of several active DC filtering approaches being investigated by the authors. This method of control of the voltage source inverter in the active part of the filter can permit selective filtering of DC side harmonic currents as necessary to meet telephone interference requirements. The VA rating of the inverter is also then minimised, and a more optimum choice of inverter voltage and current is possible. Frequency-response analyses by the MATHCAD program were used for control design and time-domain simulations by the EMTP program have verified the harmonic performance of the designed filter in an illustrative HVDC transmission scheme