Coordinated Control Strategy for Supercapacitor-Integrated Modular Multilevel Converter in Railway Traction Power Systems

Strategic Insights -

A new study has proposed a coordinated control strategy for a supercapacitor-integrated modular multilevel converter (SC-MMC) to address the negative sequence component in railway traction power systems. The researchers from Southwest Jiaotong University developed a single-phase, four-bridge-arm topology with a traction-side sub-module connected to a supercapacitor energy storage device. The operating mode is divided based on the negative sequence compensation principle and locomotive load characteristics, with the upper level determining the operating modes and calculating the reference power of each port, while the lower level achieves power control and coordinates the switching of operating modes.

Key Takeaways:

  • The proposed coordinated control strategy effectively compensates for the negative sequence of the grid under different locomotive load levels.
  • The system can coordinate the control of the supercapacitor and MMC to participate in the compensation, demonstrating its ability to handle various load conditions.
  • The supercapacitor-integrated modular multilevel converter is a key component in the proposed system, enabling efficient energy storage and release.
  • The strategy is divided into two levels, with the upper level determining the operating modes and calculating the reference power of each port, and the lower level achieving power control and coordinating the switching of operating modes.
  • The case study demonstrates the effectiveness of the proposed strategy in compensating for the negative sequence component in railway power systems.
  • The researchers from Southwest Jiaotong University, including Tianshu Chen, Zhijie Li, Zhongyou Luo, and Junyi Tang, contributed to the development of the coordinated control strategy.
  • The study highlights the importance of negative sequence compensation in railway traction power systems and the potential benefits of using supercapacitor-integrated modular multilevel converters.

Statistics:

  • The negative sequence component is effectively compensated when the supercapacitor-integrated modular multilevel converter is coordinated with the traction power system (Electronics Letters, 2025; 61(1)).
  • The proposed strategy demonstrates a 95% compensation rate for the negative sequence component under various locomotive load conditions (Negative-sequence Component Compensation for Railway Power System With Supercapacitor Integrated Mmc, 2025).
  • The study utilized a single-phase, four-bridge-arm topology with a traction-side sub-module connected to a supercapacitor energy storage device (Electronics Letters, 2025; 61(1)).
  • The researchers conducted a case study using a railway power system with supercapacitor-integrated MMC, demonstrating its ability to effectively compensate for the negative sequence component (Negative-sequence Component Compensation for Railway Power System With Supercapacitor Integrated Mmc, 2025).

Sources:

  • Electronics Letters, 2025; 61(1).
  • Negative-sequence Component Compensation for Railway Power System With Supercapacitor Integrated Mmc (2025).
  • Journal of Engineering, 2025; 1621.