Comparison of Equivalent Circuit Models of Circular Current Limiter According to Anti-Windup Methods in Grid-Forming Converter

초록

This paper compares equivalent circuit models of circular current limiter under different anti-windup strategies in a grid-forming voltage source converter (GFM-VSC). Conventional current limiting methods employing freezing-type anti-windup yield a purely resistive equivalent impedance, which limits the improvement of transient stability. To address this limitation, this paper proposes the use of a back-calculation anti-windup method, which enables shaping the equivalent virtual impedance with a desired X/R ratio. Through analytical derivation, it is shown that adjusting the back-calculation gain allows flexible control of the phase angle of the virtual impedance, thereby significantly enhancing the transient stability of the GFM-VSC. The effectiveness and superiority of the proposed method over conventional approaches are validated through simulation results.

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