Virtual Synchronous Machine Control Applied to Solid State Transformer

Implementation of Virtual Synchronous Machine control in a Solid State Transformer (VSM-SST) with an energy storage system (ESS) is proposed. The VSM-SST is able to provide inertia support to grids that are suffering from inertia lack due to the massive introduction of renewable energy. This paper first clarifies the feature requirements for the VSM-SST and then a control system that satisfies these requirements is proposed. Although the ESS may be disconnected from the SST depending on the state of charge conditions, the proposed control system is able to serve the function as the SST only by changing the control parameters. In addition, the method to detect power disturbance in the grid using a swing equation in VSM control is also proposed. The required functions of the VSM-SST for the disturbance on the grid were verified by numerical simulation and experiments using a small-size experimental system.