Virtual elastic coupling control of grid-forming wind farms for power oscillation suppression

With the increasing number of renewable energy units, the issue of inconsistent control responses among multiple grid-connected generators has become prominent. Properly grouping wind turbines to form multiple virtual elastic couplings is key to achieving efficient oscillation energy transfer in power systems, thereby creating an integrated support effect. This paper defines virtual elastic couplings between the VSGs and synchronous generators (SGs) and establishes a dynamic model of a power system with multiple degrees of freedom using these virtual elastic couplings. Based on the analysis of amplitude-frequency characteristics of the SG's rotor angle, a novel control system of VSGs with multiple virtual elastic couplings is designed. By optimizing multiple virtual elastic couplings, the electrical distances of wind turbines are compensated for consistent power response, avoiding oscillations between wind turbines that are close in distance. Moreover, to further improve the overall effectiveness of wind turbines in a regional network for oscillation suppression, a novel multiple virtual elastic couplings control scheme of the VSGs is proposed, regulating wind farms with long electrical distances to obtain appropriate degree of freedom. Finally, the proposed control strategy is tested on a controller hardware-in-the-loop platform and a New England simulation system with a high proportion of wind power. The test results demonstrate that the overall effectiveness of wind turbines for oscillation suppression can be formed through the optimization of multiple virtual elastic couplings under the proposed control strategy, thus improving the support ability of wind turbines for system dynamic stability.