| 引用本文: | 朱述超,季振东,孙毅超,等.宽电压增益和全功率范围的MMDCT子模块电容均压方法[J].电力系统保护与控制,2025,53(17):134-144.[点击复制] |
| ZHU Shuchao,JI Zhendong,SUN Yichao,et al.Submodule capacitor voltage balancing method for MMDCT operating at wide voltage gain and full power range[J].Power System Protection and Control,2025,53(17):134-144[点击复制] |
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| 摘要: |
| 模块化多电平直流变压器(modular multilevel DC transformer, MMDCT)作为直流电网中的关键设备，承担了直流电压变换、功率传输和电气隔离的功能，而其稳定运行需要对众多级联的子模块采取电压均衡控制。针对现有方法无法简单可靠地实现宽电压增益范围和全功率运行工况时的子模块电容电压平衡问题，提出了一种桥臂内子模块电容均压的控制方法。该方法通过改变各子模块驱动脉冲占空比的方式实现类两电平调制，基于不同占空比的驱动脉冲向子模块电容进行电荷量不等的充电控制，并根据电容电压的排序来确定相应子模块驱动脉冲的占空比，进而实现子模块电压均衡。所提方法使得MMDCT能够运行在宽电压增益范围和全功率运行工况下，且具有无需实时检测桥臂电流、计算量少等优点。最后通过仿真和实验验证了理论分析的正确性和所提均压方法的可行性和有效性。 |
| 关键词: 模块化多电平直流变压器 电容电压均衡 移相控制 类两电平 占空比控制 |
| DOI：10.19783/j.cnki.pspc.241052 |
| 投稿时间：2024-08-07修订日期：2025-02-18 |
| 基金项目:国家自然科学基金项目资助(51707098) |
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| Submodule capacitor voltage balancing method for MMDCT operating at wide voltage gain and full power range |
| ZHU Shuchao1,JI Zhendong1,SUN Yichao2,LI Dongye3,WANG Jianhua4,ZHAO Jianfeng4 |
| (1. School of Automation, Nanjing University of Science and Technology, Nanjing 210094, China;
2.?Electrical and Automation Engineering, Nanjing Normal University, Nanjing 210023, China;
3.?School of Electric Power Engineering, Nanjing Institute of Technology, Nanjing 211167, China;
4. School of Electrical Engineering, Southeast University, Nanjing 210096, China) |
| Abstract: |
| The modular multilevel DC transformer (MMDCT), as a key equipment in DC grids, performs DC voltage conversion, power transmission, and electrical isolation. Its stable operation requires effective voltage balancing control of numerous cascaded submodules. Existing methods struggle to reliably achieve capacitor voltage balancing of submodules under wide voltage gain and full power range. To address this, a control method is proposed for capacitor voltage balancing of submodules within an MMDCT arm. In this method, the quasi two-level modulation is realized by changing the duty cycle of the driving pulse for each submodule. Based on these varying duty cycles, unequal charging control of submodule capacitors is carried out, and the duty cycles are determined according to the sorted capacitor voltages, thereby enabling voltage balancing among the submodules. The proposed method enables MMDCT to operate under a wide voltage gain and full power range, without requiring real-time detection of arm current and with low computational complexity. Finally, simulations and experimental results validate the theoretical analysis and confirm the feasibility and effectiveness of the proposed voltage balancing method. |
| Key words: modular multilevel DC transformer (MMDCT) capacitor voltage balancing phase-shift control quasi two-level duty cycle control |
