Distributed Active Filters for Harmonic Resonance Suppression in Industrial Facilities

Significant harmonics amplification in industry facilities has been reported. This phenomenon is identified as harmonic resonance between power factor correction capacitor banks and system inductors. Conventional active filter techniques aimed at harmonic current compensation are not effective under this resonance situation. This paper proposes a distributed active filter design for harmonics damping within industry facility. In this system, the active filter operates as a harmonic conductance with a droop characteristic. A droop control bewteen the harmonic volt-ampere reactive consumption of the active filter and its harmonic conductance 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 results of a typical industry facility is implemented in this paper, and harmonic filtering performances discussed in detail. Laboratory prototype is conducted to valid the effectiveness of the proposed approach.