Research On The Control Strategy Of Directly-driven PMSG-WTS Connected To The Grid

Degradation of global environment and depletion of traditional energy sources encourage people to look for new energy sources. Among the existing forms of clean energy generation, wind power is well received as the most mature technology. The control strategy of directly-driven permanent magnet synchronous generator wind turbines (PMSG-WTs) connected to the grid under rated wind speed is the main work of this article, understanding the development of wind power currently. That is the control strategies of both grid side and generator side for PMSG-WTs based on the structure of dual PWM converter.Introduce the wind turbine system and compare the operation principle of optimum utilization of wind energy. Then choose Power Signal Feedback (PSF) control as the Maximum Power Point Tracking (MPPT) strategy. Deduce the mathematical model in synchronous rotating reference frame of PWM converter on the base of trans-vector control theory. Lead to the grid side control strategies of grid voltage space vector orientation and virtual grid flux orientation then. The former is simple and widely used, while the latter does not require line voltage sensors but the algorithm is relatively complex. A simulation is done in the case of normal operation and voltage drop fault when using the former control strategy.Do research on the mathematical model and control stategy of generator side with the converter topologies of diode rectifier + boost chopper and PWM rectifier. A comparison of id=0 and UPF control strategies based on rotor flux oriented is given then. The former is simple but the active and reactive power of generator side are not decoupled, while the latter is the opposite. Therefore propose a novel vector control strategy based on stator flux re-oriention, which combines the advantages of the two above. The control structure is deduced from the mathematical model and the double-loop is still used similar to the previous two methods. Simulations are done in the case of the three control strategies. The results show their effectiveness and correctness. At the last, the PMSG-WTs system with drive train which can reduce fluctuations of the power into grid effectively is simulated.