Harmonic resonance damping with a hybrid compensation system in power systems with dispersed generation

A hybrid compensation system consisting of an active filter and a group of distributed passive filters has been studied previously. The passive filters are used for each distorting load or Dispersed Generation (DG) unit to remove major harmonics and provide reactive power compensation. The active filter is connected in parallel with the distributed passive filters and loads/DGs to correct the system unbalance and remove the remaining harmonic components. The effectiveness of the presented compensation system has also been demonstrated. This paper studies the performance of the hybrid compensation system under system harmonic resonance. The harmonic resonance and the characteristics of harmonic sources are briefly described. The damping effects of the active filter in the hybrid filter system are analyzed with a simplified circuit. An example system including various power electronic interfaces is used to illustrate the harmonic resonance and the damping effects of the active filter. The impedance characteristics and their variation with circuit configuration are presented and the system behavior under a grid background harmonic source is studied by simulation. The simulation results have demonstrated that the harmonic resonance can be damped effectively. The hybrid filter system is an effective compensation system for dispersed generation systems. In the compensation system, the passive filters are mainly responsible for main harmonic and reactive power compensation of each individual load/DG unit while the active filter can damp the harmonic resonance, correct the system unbalance and remove remaining harmonics.