Power control experiments using a 5 MJ superconducting magnetic energy storage system

A theoretical approach to the simultaneous control of active power and reactive power that is based on decoupling control theory is proposed. The idea has been applied to a 5 MJ superconducting magnetic energy storage system connected to a 6600 V power line. The control performance was confirmed by a simulator test, a dummy test, and a real machine test. This system used a dumping resistor for protection, but the stored energy in the magnet was successfully transferred back to the power line by the phase control operation of the thyristor converter in the dummy quenching test. Operation in the permanent-current mode was also verified, and the decay time of the permanent current was consistent with loss due to the forward voltage drop of the thyristor switch.<>