中文摘要：

为优化高压直流输电（HVDC）接入点电能品质,提出一种模块化多电平选择谐波消除脉宽调制（MSHE-PWM）方法.MSHE-PWM方法在保持功率器件最低动作频率的基础上,可满足输出PWM波形低次谐波的精确消除.首先,建立了模块化多电平换流器（MMC）拓扑的基本数学模型,指出了子模块（SM）均压控制原理;分析了MSHE-PWM开关角度离线求取原理与实现方式;最后,基于MMC无功补偿实验样机进行MSHE-PWM控制性能验证.实验结果表明,所提MSHE-PWM方法满足低开关频率、无低次谐波等性能指标,验证了其应用于HVDC接入点电能品质优化的可行性和有效性.

英文摘要：

To optimize the power quality of the high voltage DC transfer connecting point, a multilevel selective harmonic elimination pulse width modulation （MSHE-PWM） method is proposed.MSHE-PWM keeps the lowest operating frequency of power device,and it can accurately to eliminate the low order harmonics.First,the basic mathematical model of modular multilevel converter（MMC） topology is established,contrast analysis of the two methods of pulse sequence modulation MMC and capacitor voltage balance mechanism of sub-module（SM）.The switch angles ottline cal- culating principle and implementation way of MSHE-PWM is analyzed.FinaUy, the control performance of MMC under MSHE-PWM is verified.The experimental results show that the proposed MSHE-PWM method meets the low switching frequency, low harmonic performance indicators, etc.The feasibility and effectiveness of the proposed method are verified by experimental results.