An improved control method of fault ride-through for DPMWT-based wind farm considering coupling effect of HVDC transmission system

With the continuous increase of wind power penetration, a large number of wind farm have been constructed. The large-scale wind farm is usually transmitted through high voltage direct current(HVDC) transmission system. The reactive power output on the grid-side converter is utilized to support grid voltage, which is a common method of fault ride-through for direct-drive permanent magnet synchronous generator-based wind turbine (DPMWT). The power control capability of DPMWT-based wind farm(DPMWF) is affected by safety constraints and operating characteristics of the external system. However, the control strategy of DPMWF cannot yet take into account the coupling effect of HVDC and may be difficult to meet the voltage recovery requirements of the grid during the grid fault. Even the DPMWT may oscillate due to the over-threshold of the control setting value. Therefore, a power coupling model between DPMWF and rectifier station of HVDC transmission system is established, and an evaluation method for the power controllability of DPMWF under fault considering the coupling effect of HVDC transmission system is proposed. A calculation method of maximum reference value of reactive power control of DPMWF based on model predictive control is proposed taking into account the con-verter constraints of DPMWF and the influence of the external system. An improved control method of fault ride-through is further proposed, which takes into account the coupling effect of HVDC transmission system. The simulation shows that the proposed method can improve the voltage recovery characteristics under the grid fault, effectively guarantee the fault ride-through of DPMWF.