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A Direct Current-Synchronization Control for Voltage Source Converter with Enhanced Fault Ride-Through Capability
  • Zheran Zeng,
  • Dongsheng Yang
Zheran Zeng
Eindhoven University of Technology

Corresponding Author:[email protected]

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Dongsheng Yang
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While grid-forming (GFM) technology has gained increased attention for voltage-source converters (VSC) connected to low-inertial AC systems, there exists a gap in addressing their fault ride-through (FRT) capability under large grid disturbances. Specifically, the challenge lies in resolving the resynchronization issue of GFM-VSCs under current-limitation mode without relying on a phase-locked loop (PLL). To bridge this gap, this article proposes a novel approach called direct current-synchronization control (DCSC), which directly regulates the VSC current for synchronization. The validity of DCSC is substantiated by establishing equivalent relationships between current and power, as well as power and phase angle. Thus, achieving synchronization by controlling the VSC phase angle is made possible through the direct control of the VSC current. The stability boundary of DCSC is theoretically analyzed, concluding that DCSC has the same stability boundary as power synchronization control (PSC) with reactive power regulation in continued normal operations but a 90-degree stability boundary under large grid disturbances, irrespective of voltage magnitude. Additionally, boundary conditions for system stability assessment during large grid disturbances are established, and a control gain self-adaptability (CGSA) scheme is introduced to accelerate resynchronization after faults. Therefore, the DCSC scheme exhibits identical control dynamics to PSC with reactive power regulation in continued normal operations, while offering enhanced FRT performance under large grid disturbances. Experimental results validate the theoretical findings, affirming the effectiveness of the proposed control method.
14 Apr 2024Submitted to TechRxiv
18 Apr 2024Published in TechRxiv