频率耦合影响下海上风电经附加频率控制MMC-HVDC并网稳定性研究OA

The grid-connected stability of offshore wind power transmission system via modular multilevel converter based high voltage direct current(MMC-HVDC)has attracted much attention in recent years.However,due to the decoupling effect of MMC-HVDC cables,the inertia of the offshore wind power transmission system via MMC-HVDC is missing.Meanwhile,the frequency coupling effect is also an important factor affecting the grid-connected stability of the offshore wind power transmission system via MMC-HVDC.Therefore,this paper aims to explore the frequency support effect of additional frequency control on the grid-connected system of offshore wind power through MMC-HVDC,complement the influence of active frequency support control on the AC admittance of MMC-HVDC,and improve the small disturbance stability analysis method of offshore wind power through MMC-HVDC under the frequency coupling effect.Firstly,an additional frequency control is put into the actual engineering model of the di-rect drive wind farm connected to the grid through MMC-HVDC,and the admittance models of the wind farm side converter station and the MMC converter station under the additional frequency control are established respectively.Secondly,the small disturbance stability analysis method of grid-connected systems under the influence of frequency coupling effect is explored.Then,the frequency coupling effect of the system is measured quantitatively,and the influence of additional frequency control on the system frequency coupling effect is concerned.Finally,a resonant suppression measure is proposed,and electromagnetic transient simulation is carried out by PSCAD/EMTDC to ver-ify the effectiveness of additional frequency control,the accuracy of the established impedance model,the correct-ness of grid-connected stability analysis and the effectiveness of the resonant suppression measure.