Wideband Dissipativity Enhancement for Multi-Sampling Controlled Grid-Following VSCs

With the gradually decreasing cost of high-performance digital processors, multi-sampling current control is a promising method to reduce the control delay and improve the high-frequency dissipativity in grid-connected converters. Specifically, with the capacitor voltage feedforward and the inverter-side current feedback, the dissipation of the multi-sampling current control can be extended up to the switching frequency. However, if the effect of phase-locked loop is considered, a non-dissipative region is still inevitable in the low-frequency area, which leads to a risk of destabilization for weak grid operations. To tackle this challenge, a virtual damping control scheme is proposed in this paper, and the non-dissipative region in the d-axis and the q-axis can be reduced to a specific range, respectively. Moreover, the transient performance is also improved compared with the conventional virtual damping method. Finally, the effectiveness of the proposed method is verified through the simulations.