Oscillation Energy Transfer and Integrated Stability Control of Grid-Forming Wind Turbines

Abstract

Efficient oscillation energy transfer between grid-forming wind turbine and synchronous generator (SG) is the key to improving the dynamic stability of regional power grid with a high proportion of renewable power generation. This paper first analyzes the elastic coupling relationship between the doubly fed induction generator (DFIG)-based wind turbines and the SGs under the grid-forming control, establishing a two-degrees-of- freedom dynamic system model incorporating grid- forming wind power generation. The root locus method is then applied to analyze the influence of virtual inertia and damping on the system's dynamic stability. Subsequently, the virtual inertia demand of grid-forming wind turbines is obtained based on the constraint of frequency change rate. Moreover, the oscillation energy transfer mechanism between grid-forming wind turbine and SG is further analyzed using the Hamiltonian energy function method. Then, a novel design scheme of the control parameters of the grid-forming DFIG is proposed using the condition for the efficient transfer of oscillation energy between generators. Finally, the proposed control is verified in the New England simulation system and a 9-node power system on the controller hardware-in-the-loop platform with high wind power penetration. The test results demonstrate that the proposed control significantly improves the grid-connected support performance of the DFIG to suppress system power oscillation and frequency change.