Present State and Future Trends of Active Power Filters in Japan

With remarkable development and advance in PWM inverter technology on the basis of fast switching devices in the 1980s, active power filters which are classified into shunt and series active filters have been studied with the focus on their practical installation in industrial power systems. In 1982, a shunt active filter of rating 800kVA was put into practical use for the first time in the world. The main circuit consisted of a current source PWM inverter using GTO thyristors. In 1986, a combined system of a shunt active filter of rating 900kVA and a shunt passive fil­ter of rating 6600kVA was practically installed to suppress the harmonics produced by a large capacity cycloconverter for steel mill drives. More than one hundred shunt active filters have been operating properly in Japan. The largest one of the shunt active filters is 20MVA, which was developed in 1990 for reactive power and harmonic compensation for an arc fur­nace with the help of a shunt passive filter of 20MVA. This paper presents a survey of shunt and series active filters using PWM inverters, paying attention to research and practical applications in Japan.