Active filters and energy storage systems operated under non-periodic conditions

This paper describes power electronics technology relevant to active filtering and energy storage for the purpose of power conditioning. The combination of active filtering and energy storage leads to a versatile system in terms of compensation under nonperiodic conditions. However, energy storage is much more difficult and costly in realization than active filtering because modern science offers only chemical action, electromagnetic or electrostatic field, and kinetic or potential energy as viable ways of energy storage. This paper is focused on the present status of active filters, and energy storage systems for power conditioning, along with a 200 MJ/20-MW flywheel energy storage system which was commercially installed on a 66 kV power system for the purpose of line-frequency regulation in 1996.