Design and implementation of a microgrid-capable solar inverter

Abstract

The notion of a practical microgrid -- a small, interconnected system of generators and loads that operates both synchronously with a larger, centralized grid and isolated from the grid, autonomously -- has grown popular as electric utilities are installed more frequently in areas lacking a pre-existing central grid. To research the effects of both intentional disconnects and unintentional faults within a microgrid and between it and the central utility, we have constructed such a system in simulation by using hardware to simulate the real-world generators and loads of the microgrid and have connected it to the MIT utility.[1] The microgrid requires a clean, efficient switching system in order to connect and disconnect its components, and this thesis begins with an explanation of the control hardware and software interface implemented to do so. Next, this thesis details the design of one of the main generating sources for the microgrid, the inverter for a hardware-simulated solar panel. Solar panels with DC output are virtually always connected through a power inverter to produce the usable three-phase AC on the power grid. This particular inverter design is intended to be control-scheme agnostic; the actual operation of it will vary with different control algorithms. It is designed to be a general purpose, three phase 2.3 kW power inverter, albeit with specifically added modules to suit this particular microgrid. This thesis covers both the design of the circuit and the finished layout of its printed circuit board.