考虑子模块均压约束的混合型模块化多电平换流器损耗分析

The Loss Calculation and Analysis of Hybrid Modular Multilevel Converter Considering Sub-Module Balancing Constraint

随着柔性直流输电工程电压等级及输送容量不断升高,模块化多电平换流器的损耗问题引起诸多关注。目前,常用的损耗分析方法都是针对全桥和半桥型模块化多电平换流器进行分析计算。基于混合型模块化多电平换流器的工作特性,文中提出了一种考虑子模块均压约束的混合型MMC损耗分析方法。该方法根据混合型MMC桥臂电压和电流在一个控制周期内的参考方向对子模块投切情况进行分析,根据不同类型子模块的投切情况对混合型MMC建立数学模型进行损耗分析计算。文中通过提取绝缘栅双极型晶体管的损耗数据进行拟合并建立数学模型,对换流器的结温和损耗之间的相互影响关系进行了详细分析。最后,通过实验仿真分析验证了所提方法的准确性。

The voltage level and transmission capacity of flexible DC transmission projects are constantly increasing,and the loss of modular multilevel converter has attracted much attention.At present,the commonly used loss analysis methods are for the analysis and calculation of full-bridge and half-bridge modular multilevel converters.Based on the operating characteristics of the hybrid modular multilevel converter,a hybrid MMC loss analysis method that considers the constraints of submodule voltage sharing is proposed in this study.According to the reference direction of the voltage and current of the hybrid MMC bridge arm in a control cycle,the sub-module switching situation is analyzed.The mathematical model of the hybrid MMC is established according to the switching situation of different types of sub-modules for loss analysis calculation.By extracting the loss data of the insulated gate bipolar transistor to fit and establish a mathematical model,the detailed analysis of the mutual influence between the junction temperature and the loss of the converter is carried out.Finally,experimental simulation analysis is performed to verify the accuracy of the proposed method.