Design of a hardware solar emulator for an experimental microgrid

Abstract

Microgrids are regions where local generation and loads are clustered together. Students from the LEES group at MIT are currently developing an experimental microgrid. This will enable various studies in the area of microgrid dynamics. The setup consists of a variety of modules that emulate both conventional and renewable sources. In this thesis, we focus on the design of one of these modules: the solar PV emulator. The complete design of a solar PV emulator will be described. Firstly, AC and DC models of a solar cell are introduced. These models specify design constraints for the power electronic circuitry. They also indicate a desired performance for the feedback control system. The controller design is discussed and the effect of load type on the closed-loop dynamics are considered. This is especially interesting for the grid-connected case. The design methodology culminates in the construction of an experimental prototype of the hardware solar PV emulator. The modular design approach is outlined as are its benefits to the overall construction of the microgrid. A Generic Controller board that can be used for all future power electronic modules in the microgrid is also designed and fabricated. The results of simulations and experiments are discussed and it is shown that it is possible for a buck converter to emulate the steady state dynamics associated with solar PV panels.