Abstract
VAr support capacitors are often installed to improve displacement power factor in industrial facilities, but they could also conduct considerable voltage and current harmonics due to harmonic resonance phenomenon. Various harmonic filter strategies have been proposed. Passive L-C filter is the most typical solution for above phenomenon. Hybrid active filter which features harmonic isolation provides an alternative. Nevertheless, they require extensive system studies to achieve a good design. In addition, conventional active filter cannot damp harmonic resonance and usually brings high cost. This thesis hence proposes a distributed active filter design for harmonics damping within industry facility. In this system, active filter operates as a harmonic conductance with a droop characteristic. The droop control between the harmonic VAr consumption Q of the active filter and its harmonic conductance G is developed to coordinate the operation among individual active filters, so that each unit can share harmonic filtering workload in proportion to the rated capacity without any communications. Simulation and laboratory prototype are conducted to validate the effectiveness of the proposed approach.