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Double Synchronous Unified Virtual Oscillator Control for Asymmetrical Fault Ride-Through in Grid-Forming Voltage Source Converters

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posted on 15.06.2021, 04:09 by M A AwalM A Awal, Md Rifat Kaisar Rachi, Hui YuHui Yu, Iqbal Husain, Srdjan Lukic
A double synchronous unified virtual oscillator controller (dsUVOC) is proposed for grid-forming voltage source converters to achieve synchronization to the fundamental frequency positive- and negative-sequence components of unbalanced or distorted grids. The proposed controller leverages a positive- and a negative-sequence virtual oscillator, a double-sequence current reference generator, and a double-sequence vector limiter. Under fault conditions, the controller enables to clamp the converter output current below the maximum value limited by the converter hardware while retaining synchronization without a phase-locked-loop (PLL) regardless of the balanced or unbalanced nature of grid faults. Consequently, balanced and unbalanced fault ride-through can be achieved without the need for switching to a back-up controller. The paper presents the systematic development of the double-synchronous structure along with detail design and implementation guidelines. Validation of the proposed controller is provided through extensive control-hardware-in-the-loop (CHIL) experiments.

History

Email Address of Submitting Author

mawal@ncsu.edu

ORCID of Submitting Author

0000-0001-6201-5089

Submitting Author's Institution

North Carolina State University

Submitting Author's Country

United States of America