Novel Active Filter System Composed of Inverter Bypass Circuit for Suppression of Harmonic Resonance

Abstract

We have developed and proposed a novel harmonic compensation system consisting of shunt LC filters on load side, a step-down transformer on receiving end, and a small capacity active filter which one end is connected to the secondary winding of the transformer and the other to the load bus.
The active filter which just constitutes the bypass-circuit against the main service transformer is current-controlled to give adequate damping to the harmonic resonance condition caused between the inductance behind the load bus and the capacitance of var equipment on the load bus especially at lower harmonic frequencies.
We have installed this new scheme of harmonic compensation system in combination with TCR-type SVC and shunt LC filters at the Yamanashi Maglev Test Line.
We will describe the outline of the reactive power and harmonic current compensation systems, and harmonic resonance test results which show satisfactory performance of the active filter.