Charging and discharging characteristics of SMES with active filter in transmission system

For SMES (Superconducting Magnet Energy Storage) composed of Superconducting Magnet (SM) and thyristor converters, the harmonic currents which are generated by SMES converter should be compensated. We have developed active filter, the output of which is adaptively controlled such that the deviation of the waveform of ac line current from the sinusoidal one can be cancelled out. SMES system composed of two sets of GTO (Gate Turn-Off) thyristor converter, 0.5 MJ pulsed SM which are controlled by a direct digital controller, and the active filter, has been developed. The SMES system has been connected to a model power transmission system together with a 10 kVA generator. The controlled characteristics of SMES in the model power transmission system and compensated characteristics of active filter have been experimentally studied. The experimental results show that harmonic currents of SMES can be successfully compensated by active filter, and simultaneous active and reactive power control of SMES can be carried out without the influence of harmonic distortion.