New approach to estimate harmonic source of power system utilizing operation data of active filter

Many power electronic equipments are successfully employed in various fields due to their high efficiency operation, energy saving, etc. However, these produce some harmonic current, which flow into electric power systems. As a result, it is evident that large harmonic currents make the quality of electric power inferior and it is important to take a measure to meet a reasonable quality level. Estimating of harmonic equivalent circuit including harmonic source will be useful to do it. In this paper, we propose a new approach to estimate the harmonic sources using many operating data of an active filter installed for suppressing harmonic current, and a method to separate the inflow and outflow harmonic currents from the upstream side and downstream side harmonic sources, respectively, at the installing point of the active filter. The usefulness of the proposed methods are experimentally confirmed using two types of rectifier circuits.