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Wide-bandgap Modular Architecture for Medium Voltage Energy Conversion in Utility-scale Wind and Solar

Title: Wide-bandgap Modular Architectures for Medium Voltage Energy Conversion in Utility-scale Wind and Solar
PI: Brian Johnson

Funding Source: National Renewable Energy Laboratory R&D Program.

Period: 2017 – 2019.

Abstract: The proposed concept bridges advances in wide-bandgap devices with breakthroughs in distributed and decentralized control to produce next-generation medium voltage power conversion circuits that are scalable in both architecture and control. Taken together, the proposed circuit designs and accompanying control strategies will yield integrated circuit+control (C2) blocks, each comprising a local controller and converter, that can be assembled in a modular fashion to obtain highly distributed conversion interfaces for next-generation renewable system architectures. The envisioned application entails the use of silicon carbide (SiC) devices to obtain C2 blocks that each operate at a voltage and power in excess of 1kV and 100kW, respectively, such that ensembles of series-connected blocks perform direct ac-dc conversion at medium voltages (e.g., 12kV–35kV). Leveraging SiC devices operating at high switching frequencies (>100kHz), the envisioned cascaded circuit structures will yield transformative performance gains in efficiency while eliminating bulky components and low-frequency transformers. From a reliability standpoint, the elimination of large capacitor banks coupled with online reliability monitoring and wear-mitigation enabled by digital control will increase system lifetime. Contemporary advances in decentralized and distributed control will be leveraged to circumvent single points of failure and afford an overall resilient system that functions despite faults at the block level. The envisioned project outcome is a suite of dc-dc, dc-ac, and ac-dc architectures that can be applied to a variety of renewable energy applications. This project is led by Brian Johnson and includes a collaborative effort between the NREL and the University of Colorado Boulder.