Black start control of a solid state transformer for emergency power restoration

This paper demonstrates the black start capabilities of a single phase 20kVA solid state transformer (SST), specifically for microgrid power restoration during islanding. SST´s have many benefits including better management of renewable energy resources and more intelligent control than the classical transformer which acts only as a passive device. An additional benefit of the SST that is demonstrated in this paper is the ability to use these renewable energy resources directly connected to the SST to restore microgrid load power during an islanding event. During the black start procedure the SST can switch the control operation of its three cascaded power converter stages, AC/DC rectifier, Dual Active Bridge, and DC/AC inverter, in order to restore the microgrid load. The benefits of using the SST for black start restoration are also discussed and compared with other traditional methods.