Flexible unbalanced control with peak current limitation for virtual synchronous generator under voltage sags

Abstract

Virtual synchronous generator (VSG) is gridfriendly for integrating distributed generations (DGs) since it can emulate the operation mechanism of traditional synchronous generator (SG). However, the traditional VSG control strategy, which is mainly suitable for balanced voltage conditions, may lead to power oscillations, current unbalance and even overcurrent under unbalanced voltage sags. To overcome this difficulty, a flexible unbalanced control with peak current limitation for VSG under unbalanced operating conditions is proposed. Based on the basic VSG control algorithm, the control strategy integrates two novel control modules, which are current reference generator (CRG) and power reference generator (PRG). The proposed control strategy can flexibly meet different operation demands, which includes current balancing, constant active or reactive power. And the injected currents are kept within safety values for a better utilization of the VSG power capacity. Furthermore, the experimental platform is built. Experimental results demonstrate the validness and effectiveness of the proposed control strategy.

Positive-Negative Sequence Current Controller for LVRT Improvement of Wind Farms Integrated MMC-HVDC Network

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Extensive technique for grid‐connected converter power generation maximisation during asymmetrical grid voltages

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