Superconducting Magnetic Energy Storage (SMES) for Energy Cache Control in Modular Distributed Hydrogen-Electric Energy Systems

The proposed energy cache control enables fast compensation of stochastic power fluctuations through the use of Superconducting Magnetic Energy Storage (SMES) connected to the DC bus of Distributed Generation (DG). The term energy cache control is chosen to reflect its analogy to the utilization of the data cache in computers. The SMES provides an energy cache for other types of storage with a higher capacity of energy but also longer response times. Together, the two types of storage provide high controllability over diverse time scales. The SMES so enables the creation of modular DG building blocks which can be readily connected to the network in a plug-and-supply mode. In the developed case study, the SMES is part of a DG unit of a model commercial facility that includes renewable-based electric power generation and a hydrogen-electric conversion and storage plant composed of an electrolyser, a fuel cell, and tanks. It is shown how the cache energy control deals with fast fluctuations of power generation and load that are caused by changing wind and sudden power demands of an elevator, respectively. Through its shock-absorbing role, the energy cache control of the SMES prevents the involved disturbances from propagating over the network interface and makes the DG unit behave as a good citizen in terms of network integration.