中点钳位型中压三电平风电变流器的损耗分析

Power Loss Analysis of NPC Medium-voltage Three-level Converters for Wind Power Generation System

中点钳位(NPC)型中压三电平变流器在兆瓦级风电机组中具有广阔的应用前景。由于变流器容量及电压等级较高,功率器件的损耗是一个不容忽视的问题。文中详细分析了各个功率器件的开关动作与实际电流通路,在此基础上推导了其损耗的实用计算公式,指出了损耗在机侧变流器和网侧变流器之间的不同分布,为变流器的散热设计提供参考,并结合风力发电的特点,研究了功率波动对变流器效率的影响,得出了变流器的效率与功率成正相关的结论。最后,通过MATLAB/Simulink与GH Bladed的联合仿真系统,对分析结果进行了验证。

The neutral point clamping (NPC) three-level converters have broad application prospects with megawatt wind turbines.The power losses of the switching devices must be considered in such high-power applications.Practical loss-calculating formulas are derived based on the analysis of the conduction and switching principles of the converters.The difference between the motor-side power converter (MPC) and the grid-side power converter (GPC) in power losses distribution is identified.Combined with the characteristics of wind power,the influence of power fluctuation on efficiency is also analyzed.It is concluded that the efficiency has positive correlation with the converted power.Simulation results of a co-simulation platform using MATLAB/Simulink and GH Bladed show the validity of the analysis.