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Description

With a major increase in the integration of renewable and distributed energy resources along with the use of solar inverters in microgrid applications, the need for advanced power electronics, specifically smart inverters, is higher than ever. It is desirable for these smart inverters to operate with maximum efficiency as well as provide grid services such as voltage and frequency regulation. A smart inverter design can improve the reliability and resilience of the grid, reduce the cost of energy, and ease grid maintenance. This is done through the management of active power generation and reactive power compensation between the solar inverter and the electric grid. Enhanced designs have the potential to increment efficiency, reduce system loss-related heatsink size, and minimize installation cost. The purpose of this research is to develop a smart solar microgrid inverter. This design shall prove to be low cost with high efficiency and power density. The goal of our team is to identify trade-offs between efficiency, cost, and volume. In addition, our team seeks to achieve innovations in circuit topologies and smart inverter control strategies, optimization in circuit parameters, and the application of highly efficient wide-bandgap devices. Two stages are realized in the microgrid inverter design: a DC-DC stage and a DC-AC stage. The DC-DC stage employs a frequency-modulated LLC resonant converter with zero-voltage switching (ZVS) for a wide load range. The DC-AC stage consists of a grid-connected three-leg converter which can be operated in a single-phase or three-phase mode depending on the number of legs that are switched. The possibility of using a single converter for both modes reduces the number of circuitries needed in the system. Consequently, this increases the power density of the system. Stiff DC link is employed to have a decoupled system that helps in closed-loop control and provides flexibility to scale the converter to process more power. The DC-DC stage can be modularized, and the DC-AC stage can be scaled as needed to process more power. Wide-Bandgap GaN devices are chosen to implement the converter’s DC-DC and DC-AC stages owing to their inherently superior Figure-of-Merit (FOM) that helps improve performance. Higher frequency operation is proposed for both stages to improve the overall power density and have higher control bandwidths.

Publication Date

12-9-2021

City

Logan, UT

Keywords

renewable energy, smart inverters, solar power, power density

Disciplines

Electrical and Computer Engineering

Smart Solar Microgrid Inverter

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