Superconducting cable with energy storage function and its potential for next-generation power system compatible with large-scale renewable energy installation

The mass introduction of renewable energy is essential to realize a sustainable society. On the other hand, when photovoltaic (PV) and wind power generation are used as main power sources in a power system, it is indispensable to compensate for their severe output fluctuations up to the rating of the power system; however, this is difficult to achieve with conventional energy storage devices alone. To solve this problem, we have proposed a superconducting cable with energy storage function and its use in a DC power system. This cable provides large inertia to the power system without the need for additional energy storage equipment; as a result, the power system itself become capable of high-speed and high-power compensating operations for output fluctuations from renewable energy sources. This paper summarizes our recent works on this research topic: an overview of the proposal, conceptual design of the cable, experimental verification of the principle, and positive effects on the energy use efficiency of renewable energy. For example, an experiment with the use of a small model cable showed the capability of high-speed charge-discharge operations at a high power up to the rating of the microgrid. It was also showed that such a function was indispensable for real-time use of electric power from PV power generation resulting in significant enhancement of energy use efficiency of renewable energy. These results suggest that this concept hold the key to next-generation power systems enabling massive use of renewable energy in the future society.