Single-phase three-stage SST modeling using RTDS for controller hardware-in-the-loop application

In order to develop and validate smart grid technologies with complex control and communication, detailed modeling of distribution systems using the Real Time Digital Simulator (RTDS) is invaluable [1]. At the distribution system level, testing a 13 kV power electronic device without first validating its controls is cost prohibitive. RTDS provides a cost effective way to study smart grids at not only the system level but also at the device level. The difficulty of modeling the distribution system using RTDS lies in the power electronic devices in the system such as single-phase three-stage solid state transformers (SST) and distributed energy storage devices (DESD) due to their fast transients. This paper investigates the low-loss two-level VSC bridge (LEV2) switching model in RTDS and solves the artificial loss problem for single phase systems. Then, the modeling method is applied to a controller hardware-in-the-loop (CHIL) setup with an SST and DESD, showing promising results. Finally, with the actual DSP+FPGA board for control and an ARM TS7800 for communication, the SST modeled in RTDS is controlled over Ethernet.