Research on Maximum Power Tracking Control Method of 10MW MVSPMSG Based on Neutral Point Potential Balance

Abstract

In order to meet safety and stability grid-connected requirementsof high-power offshore wind turbines, the 10 MW wind power generation system composed of medium voltage six phase permanent magnet synchronous generator (MVSPMSG) and distributed neutral point clamped (NPC) converter is adopted. On the basis, a maximum power point tracking control (MPPT) method of 10 MW MVSPMSG based on neutral point potential balance is studied in the paper.Firstly, the optimal reference torque of MVSPMSG is calculated according to speed feedback, and the double d-q current control loop of stator is designed based on the doubly fed decoupling. The MPPT of MVSPMSG is realized by the closed-loop combination of torque loop and double d-q current loop. Secondly, in order to suppress the fluctuation of DC neutral point potential, a midpoint potential balance coordinated control method based on modulation coefficients and vector group selection is proposed. The mid-point potential fluctuations is suppressed by adjusting the magnitude of the modulation coefficient in the normal range. The vector group selection method is collaboratively added to the midpoint potential balance control based on small vectors when the modulation coefficient exceeds the limit. Finally, the effectiveness of the proposed MPPT control strategy and midpoint potential balance strategy are verified, which provides a theoretical reference for the control of high-power permanent magnet wind turbine.