基于MPPMSG及混合式3L变流器的新型风电变换系统的设计和比较

在MW级大功率直驱风电系统中,发电机出口电压等级经常采用较低的690V,因此额定电流等级比较高,这对于全功率变流器设计是不利的.常规的解决方案是采用传统的两电平变流器并联来分摊容量,但是这是一种效率不高的解决方案.相比之下,多电平变流器具有较高的效率以及优越的谐波性能,只是在低压应用中半导体成本很高,而且还存在电容电压...

Design and Comparison of Novel Wind Power Conversion System Based on MPPMSG and Hybrid 3L Converters

The stator voltage is usually 690V in large direct-drive wind generator. Due to the high current rating, the full-size converters are difficult to be designed and manufactured. The conventional solution is to use several two-level converters connected in parallel to apportion power averagely. But this is not a high-efficiency solution. Compared to this solution, the multi-level converters present higher efficiency and better harmonic performance. But it is a little expensive for the multilevel converters to be used in low voltage system due to high cost of semiconductor devices. And the balance control of capacitor voltage is still a problem. A solution of combinational three-level converters based on multi-phase permanent magnet synchronous generator (MPPMSG) is discussed. It's a good substitution for the conventional two-level converter solution. By series and parallel combination of three-level converters, the new solution will overcome the capacitor voltage unbalance and suppress the capacitor voltage fluctuation caused by the modulation method. The cost is comparative with the conventional solution. Furthermore this solution presents higher efficiency. Several key problems of the new solution are discussed, such as the circuit topology, parameter design, capacitor voltage balance control and power losses.