Application of a commutation type reactor restricting 5th harmonic resonance in distribution power system

In Japan, harmonic problems occurring at power capacitors with 6% series reactors in distribution systems is one of the most serious problems. The resonance frequency between the power capacitor and the 6% series reactor is usually 4.08th harmonic (about 240 Hz), which is near the 5th harmonic. When the 5th harmonic of line voltage becomes larger, the increasing of the current leads to the decrease of impedance of series reactor due to magnetic saturation of iron core of the reactor. Then the 5th harmonic resonance between the power capacitor and the 6% series reactor occurs, and huge current instantaneously flows. The development of devices suppressing the 5th harmonic resonance is an important issue. In this paper, a new type of harmonic resonance compensator attached to the power capacitor is proposed, which is called a commutation type reactor. The effectiveness of the proposed compensator is discussed through some numerical simulations.