Active and hybrid filters for power conditioning

This paper describes principles, system configurations, control strategies and implementations, and filtering characteristics of active and hybrid filters for power conditioning. Their practical applications are expanding not only into office-buildings, hospitals, water supply utilities and rolling stock but also into electric power utilities. For example, a hybrid filter consisting of a 5 MVA series active filter and a 25 MVA shunt passive filter has been installed at the Yamanashi test line for high-speed magnet-levitation trains. The series active filter makes a great contribution to damping of harmonic resonance between the supply inductor and the shunt passive filter.