Article, 2023

Medium-frequency and sub-synchronous oscillation analysis of direct-drive wind farms connected to the parallel-compensated AC grid

In: Electric Power Systems Research, ISSN 1873-2046, 0378-7796, Volume 216, Page 109061, 10.1016/j.epsr.2022.109061

Contributors (8)

Shao, Bingbing (0000-0002-8670-2286) (Corresponding author) [1] Xiao, Qi [1] Meng, Xiaoxiao [1] Han, Ping Ping [1] Ma, Wei [2] Miao, Zilong [3] Blaabjerg, Frede (0000-0001-8311-7412) [4] Chen, Zhe (0000-0003-3404-6974) [4]


  1. [1] Hefei University of Technology
  2. [NORA names: China; Asia, East]
  3. [2] State Grid Corporation of China (China)
  4. [NORA names: China; Asia, East]
  5. [3] Institute of Energy, Hefei Comprehensive National Science Center
  6. [4] Aalborg University
  7. [NORA names: AAU Aalborg University; University; Denmark; Europe, EU; Nordic; OECD]


Parallel compensation is widely used for reactive power compensations, which improves the voltage quality of power grids. However, the direct-drive wind farms connected to the parallel-compensated AC grid face the risk of oscillations. In light of this, the small-signal model of multiple direct-drive wind turbines connected to the parallel-compensated AC grid is firstly built. Then, the medium-frequency and sub-synchronous inside-wind-farm/wind-farm-grid oscillation characteristics are analyzed with the eigenvalue-based method. Finally, the oscillation interactions among multiple wind turbine generators in the homogeneous/heterogeneous wind farms are investigated. The analytical results show that the inside-wind-farm medium-frequency oscillation is mainly affected by the DC voltage outer loop control of wind farms, and the wind-farm-grid sub-synchronous oscillation is mainly affected by the phase-locked loop control of wind farms and the parallel-compensated AC grid. Meanwhile, the wind turbine generators in the homogeneous and heterogeneous wind farms present strong oscillation interactions and weak oscillation interactions, respectively. PSCAD/EMTDC simulations are performed to verify the theoretical analysis.


AC grid, EMTDC simulation, PSCAD/EMTDC simulation, analysis, analytical results, characteristics, compensation, control, direct-drive wind turbines, direct‐drive wind farm, eigenvalue-based methods, farms, generator, grid, interaction, light, loop control, medium-frequency oscillations, method, model, multiple wind turbine generators, oscillation analysis, oscillation characteristics, oscillation interactions, oscillations, outer loop control, parallel compensation, phase-locked loop control, power compensation, power grid, quality, reactive power compensation, results, risk, risk of oscillation, simulations, small-signal model, sub-synchronous oscillation, sub-synchronous oscillation analysis, theoretical analysis, turbine, turbine generator, voltage outer loop control, voltage quality, wind farms, wind turbine generators, wind turbines