Exploration and Verification Analysis of YBCO Thin Film in Improvement of Overcurrent Stability for a Battery Unit in a SMES-Battery HESS

This article puts forward a method based on high-temperature superconducting (HTS) current limiting technology, to improve the overcurrent stability for a battery unit in a superconducting magnetic energy storage (SMES)-battery hybrid energy storage systems (HESS). In contrast to supercapacitors, flywheels and other energy storage systems, SMES-battery HESS possess the technical properties of power capacity, energy, and response speed, among others. Thus, SMES-battery HESS may be utilized to handle power swing, energy transfer, voltage fluctuation, and related transient stability issues. But an overcurrent in a battery unit is harm to its cycle life of the battery. Hence, the internal protection system of the battery unit is used to remove a fault by cutting off its outputs. In this article, a YBa2Cu3O7-X (YBCO) thin film is employed as the protection device to limit the overcurrent in a battery unit. In normal operation, the thin film is in the superconducting state, and its influence on the system can be ignored. An overcurrent will be limited evidently lower than the action threshold of the internal protection system by the quench resistance of the thin film. Therefore, the whole outputs of a battery unit will not be interrupted and restarted. Through the verification experiment carried out in our laboratory, the proposed protection method operated as expected, and the stability, as well as the reliability of the battery unit, could be improved.