In the bustling world of urban transportation, metro systems are the lifeblood of many cities, ferrying millions of commuters daily. Yet, the operational safety and efficiency of these systems hinge on the stability and reliability of their power supply systems. A recent study published in *Control and Automation* (Kongzhi Yu Xinxi Jishu) sheds light on a critical issue plaguing metro power supply systems: DC bus voltage resonance. Led by WANG Nanqing, the research delves into the complex dynamics of nonlinear oscillations in bus voltage, offering insights that could revolutionize the energy sector.
As metro systems face increasing traffic density and the integration of new energy systems, their power supply systems are subjected to significant fluctuations in electrical characteristics. “The problem of nonlinear oscillations in bus voltage is a pressing concern,” notes WANG Nanqing. “These oscillations can lead to chaotic waveforms, which in turn affect the stability of the power supply system.”
To tackle this issue, WANG and his team established a mathematical model of the third-order nonlinear nonautonomous equation of state for the rectifier transformer circuit at the AC side. By introducing a time dimension, they transformed the third-order nonautonomous system into a fourth-order autonomous system. This allowed for a comprehensive numerical analysis of the system’s three-dimensional phase diagrams, phase plane diagrams, Poincare mapping diagrams, and bifurcation diagrams.
The results were striking. The chaotic waveforms obtained from simulations were compared with the oscillation voltage waveforms measured on site after 24-pulse rectification. The comparative analysis revealed that the simulated waveforms closely matched the recorded waveforms in terms of amplitude and frequency. This alignment underscores the role of significant power grid fluctuations in inducing nonlinear oscillations in the traction power supply system of metro systems.
The implications of this research are far-reaching. Understanding the mechanisms behind DC bus voltage resonance can lead to the development of more stable and reliable power supply systems for metro networks. This, in turn, can enhance the overall efficiency and safety of urban transportation systems, benefiting both commuters and the energy sector.
As WANG Nanqing explains, “Our findings provide a foundation for further research into the dynamical behavior of metro power supply systems. By addressing the issue of nonlinear oscillations, we can pave the way for more robust and efficient energy solutions.”
The study, published in *Control and Automation*, marks a significant step forward in the field of metro power supply systems. It highlights the importance of addressing DC bus voltage resonance and offers valuable insights for future developments in the energy sector. As cities continue to grow and evolve, the need for stable and reliable power supply systems becomes ever more critical. This research not only sheds light on the challenges ahead but also points the way toward innovative solutions that can shape the future of urban transportation.