Study on Maximum Power Tracking Strategy of 10 MW Medium Voltage Six-Phase Direct-Drive Permanent Magnet Wind Turbine

Abstract

In order to maximize the grid-connected power of high-power offshore wind turbines, a maximum power tracking strategy suitable for medium voltage six-phase permanent magnet synchronous generator (MVSPMSG) was proposed in the paper based on the use of MVSPMSG and distributed neutral point clamped converters to form a 10 MW wind power generation system. The optimal reference value of torque was given according to the speed feedback value, and the dual dq current control loop of the permanent magnet synchronous generator (PMSG) stator winding was designed through the feedforward decoupling method. The maximum power output control of the MVSPMSG was completed by the closed-loop combination of torque and double dq current loop. At the same time, a midpoint potential balance method with modulation coefficient and vector group selection coordinated adjustment was proposed to suppress the neutral point potential fluctuations on the DC side of the neutral point clamped converter. The method of adjusting the magnitude of modulation coefficient to suppress the fluctuation of the neutral point potential was first adopted. Meanwhile, the coordination vector group selection was applied to control the neutral point potential balance when the modulation factor exceeds the limit. Finally, a 10 MW permanent magnet wind power generation system model was established in MATLAB to verify the effectiveness of the control strategy proposed in the paper.

Keywords

• wind power
• six-phase permanent magnet synchronous generator
• distributed neutral point clamped converter
• maximum power tracking
• neutral point potential balance