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This paper investigates a new DC voltage sag compensating scheme by using hybrid energy storage (HES) technology involved with one superconducting magnetic energy storage (SMES) unit and one battery energy storage (BES) unit. Two fault simulations of power supply fluctuation and sensitive load fluctuation are carried out to evaluate the dynamic voltage and power smoothing behaviours. The results obtained show that this HES-based DC voltage sag compensator has the ability to suppress the discharging / charging current overshoots for the BES unit and to enlarge the voltage compensating time for the SMES simultaneously. [ABSTRACT FROM AUTHOR]

The fast-response feature from a superconducting magnetic energy storage (SMES) device is favored for suppressing instantaneous voltage and power fluctuations, while the low-cost feature from a conventional battery energy storage (BES) device suits to achieve long-time voltage and power compensations in the power distribution and utilization systems. This paper investigates a new dc voltage swell compensating scheme by using an SMES-BES-based hybrid energy storage technology. In the preliminary tests, an iron-core copper coil is used to imitate high-temperature superconducting inductor, and this SMES emulator is, then, combined with a lead-acid battery to form a dc voltage swell compensator device. The experimental results demonstrate the feasibility of this SMES-BES-based dc voltage swell compensator to avoid the initial impulse charging current for the lead-acid battery and to extend the steady compensating time duration for the SMES simultaneously. [ABSTRACT FROM AUTHOR]

To operate a converter at cryogenic temperatures, understanding the characteristics of power semiconductor devices is critical. This paper investigates the temperature and current dependence of the dynamic performance of five types of SiC power MOSFETs at 77 K. The turn-on and turn-off lasting time and the corresponding switching energy loss are extracted from a series of double-pulse tests. The transient peak voltage of cryogenic MOSFETs is lower, but the switching time is higher than the room-temperature ones. Moreover, power-exponential functional relations with the operating currents are found in the experiments. These results obtained lay some technical bases for exploring superconducting power electronics. [ABSTRACT FROM AUTHOR]