Dissipativity Robustness Enhancement for <i>LCL</i>-Filtered Grid-Connected VSCs With Multisampled Grid-Side Current Control
Shan He, Zhiqing Yang, Dao Zhou, Xiongfei Wang, Rik W. De Doncker, Frede Blaabjerg
Abstract
Capacitor current active damping is a common method to achieve dissipation for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> -filtered grid-connected converters using grid-side current control. However, the dissipative characteristic of converter output admittance near the critical frequency can easily be jeopardized by the filter parameter deviation. Besides, the grid voltage feedforward is often overlooked when designing dissipativity, which is, however, preferred to improve transient performance. To tackle these challenges, a multisampled current control scheme is proposed in this article. By combining the capacitor current active damping and the capacitor voltage feedforward, not only the dissipation can be achieved below the Nyquist frequency but also the dissipativity robustness against the filter parameter deviation is enhanced. Besides, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> -filter resonant frequency can be designed near the critical frequency, which simplifies the internal stability design. Finally, the effectiveness of the proposed method is verified through the experiments.