Mechanism and Influencing Factor Analysis of High Frequency Oscillation in PMSG-Based Wind Farm With Grid-Connected System

Under the background of vigorously developing wind power, permanent magnet synchronous generator (PMSG)-based wind turbines have been widely used in offshore wind farms. However, the high frequency oscillations (HFOs) of PMSG-based wind farms with grid-connected system have occurred frequently in recent years, which have a bad impact on the safe and stable operation of the power system. And current researches only preliminarily reveal the mechanism, which are lacking in discussion on the key factors involved in HFOs. This paper establishes the high frequency impedance model of PMSG-based wind farm with grid-connected system. To identify the key factors involved in HFO, the impedance sensitivity method is used to obtain the quantitative relationship of the influence of each parameter on HFO. It can be concluded that the control delay, LCL filter parameters, collector lines parameters have the greatest influence on the HFO of the wind farm, but the characteristic of negative resistance caused by control delay is the root cause of HFO. Finally, this paper establishes the model of PMSG-based wind farm with grid-connected system on the PSCAD/EMTDC and verifies the correctness of the theoretical analysis. The conclusions of this paper can provide a reference basis for the mitigation strategies of HFOs.