一种抑制模块化多电平变换器光伏系统共模电压的脉冲衔尾排布调制  

A Nose-to-Tail Pulse Arrangement Modulation for Suppressing Common Mode Voltage of Modular Multilevel Converter Photovoltaic Systems

作　　者：潘尧 孙孝峰[1] 蔡瑶 李昕[1] 赵巍[1] Pan Yao;Sun Xiaofeng;Cai Yao;Li Xin;Zhao Wei(Key Lab of Power Electronics for Energy Conservation and Motor Drive of Hebei Province Yanshan University,Qinhuangdao 066004 China)

机构地区：[1]燕山大学电力电子节能与传动控制河北省重点实验室,秦皇岛066004

出　　处：《电工技术学报》2025年第4期1221-1235,共15页Transactions of China Electrotechnical Society

基　　金：河北省重点研发计划项目(19214405D);河北省自然科学基金重点项目(E2021203162)资助。

摘　　要：光伏模块利用模块化的特点,可以分布集成在模块化多电平变换器子模块的直流侧,构成基于模块化多电平变换器的光伏系统(MMC-PVS)。由阴影遮挡、损坏等问题引起的光伏模块功率不平衡会使子模块的调制信号存在显著差异,严重降低现有共模电压抑制方案的抑制效果。为了解决这些问题,该文提出一种脉冲衔尾排布调制,能够在光伏模块功率不平衡工况下抑制MMC-PVS的共模电压。通过分析光伏模块功率不平衡工况下MMC-PVS,实现零共模电压的条件,表明理论上子模块的调制信号具备实现零共模电压的能力,而由调制策略生成的子模块驱动脉冲是产生共模电压的关键因素。脉冲衔尾排布调制能将子模块驱动脉冲依次衔尾排布,即后一子模块的上升沿时刻与前一子模块的下降沿时刻对齐,在每个开关周期内保证三相上桥臂总电压与三相下桥臂总电压的形状相同,达到理论上零共模电压的效果,实现共模电压抑制。最后,通过仿真与实验验证了脉冲衔尾排布调制在光伏模块功率不平衡工况下抑制共模电压的可行性与理论分析的正确性。In modular multilevel converter-based photovoltaic systems(MMC-PVSs),the PV power imbalance caused by shadowing leads to differences among modulation signals of sub-modules(SMs)and further changes the characteristics of the high-frequency common mode voltage(CMV)of the MMC-PVS AC port.Thus,the existing high-frequency CMV suppression methods can not eliminate the high-frequency CMV of MMC-PVS.This paper analyzes the elimination condition of the high-frequency CMV.That is,the sum of the upper arm voltages of three phases is always the same as that of the lower arm voltages of three phases at any time.According to the control loop,the sum of pulse widths of all SMs in the three phases’upper arm and lower arm are equal,illustrating that zero-CMV is feasible from the aspect of the control loop.Thus,the key is to shape the arm voltages using the modulation method to satisfy the zero-CMV condition.Then,the principle of SM modulation signal difference caused by PV power imbalance is revealed and illustrated:a high PV module power results in a high SM modulation index and a high risk of over-modulation.This paper proposes a nose-to-tail pulse arrangement modulation to eliminate the high-frequency CMV of MMC-PVS under PV power imbalance conditions.The basic principle of nose-to-tail pulse arrangement modulation is to arrange the SM pulse voltages in sequence;namely,the rising edge time of the current SM pulse voltage is aligned with the falling edge time of the previous SM pulse voltage.Accordingly,the shapes of the sums of the three-phase upper arm voltages and the three-phase lower arm voltages are the same during one switching period,and the condition of zero-CMV is satisfied.Compared with the sawtooth carrier,the rising time and falling time of each SM are determined by the duty cycle of the SM during each switching period to obtain the rising and falling edges of the SM pulse voltage.Then,according to the derived logical expression,the SM switching function can be generated.With the generated switching function of e

关 键 词：模块化多电平变换器 光伏系统 光伏功率不平衡 共模电压 脉冲衔尾排布调制 

分 类 号：TM464[电气工程—电器]