Frequency-Voltage Active Support Strategy for Hybrid Wind Farms Based on Grid-Following and Grid-Forming Hierarchical Subgroup Control

Abstract

The GFL-GFM hybrid wind farm (HWF) combines the voltage source control advantages of grid-forming (GFM) wind turbines (WTs) with the current source control advantages of grid-following (GFL) wind turbines. It becomes a new type of large-scale grid-connected wind power generation. In this paper, we propose an HWF frequency-voltage active support based on GFL and GFM hierarchical subgroup control. It aims to realize the support of active power and reactive power under the premise of ensuring system stability. The strategy consists of the determination of the control objectives of the GFM-GFL subgroups, the distributed control (DC) of the GFM-GFL subgroups, and the adaptive control and switching of each unit of the GFM and GFL groups. The GFM-group maintains the grid-connected voltage stability and the GFL-group exhausts the active support. DC at the group level and adaptive control at the unit level are included under the hierarchy of the respective objectives. Finally, a GFL-GFM HWF model is established on the MATLAB/Simulink platform, and the simulation verifies that the proposed strategy can realize the enhancement of the frequency-voltage support capability of the HWF under the premise of grid-connected stability.