Integrating renewable energy resources with energy storage for grid-connected systems

Renewable energy resources have been growing at a rapidly accelerating rate as an alternative for fossil fuels in the modern electric grid. As their penetration increases, variability in these resources, particularly wind and solar, poses a risk of instability on the grid. Energy storage can be used to mitigate this risk as well as provide other benefits to the larger grid. In this dissertation, a novel high frequency common bus multiport converter is proposed as a new integration scheme to improve efficiency of the power electronics interface by reducing the number of conversion steps and to reduce the system size by replacing the line frequency transformer with a high frequency transformer tied to the common bus. Two main innovations are introduced: a new switching scheme for the H-bridges on the common bus which allows them to operate in parallel without interfering in each others operation, and a novel single-phase to three-phase matrix converter which converts the high frequency bus to the line frequency in a single conversion stage. This proposed converter is simulated to develop the inner loop control methodology, then a low power prototype is constructed and tested to verify its operation. The results of these tests demonstrate the feasibility of the proposed ideas as well as suggesting new avenues of research to further improve the proposed system.