Background: The traction power supply system (TPSS) of railways mainly focuses on power quality analysis. In the study of harmonic and negative order currents, many literature analysis are not specific enough， there is a lack of completeness in the simulation system. Objective: Analyze the influence of harmonic and negative sequences of TPSS on the system circuit, and realize intelligent recognition for different working conditions. Methods: The converter is designed based on the transient direct current control technology and the harmonic model of grid-side regenerative braking is established. According to the parameters of CRH2 (CRH380AL) locomotive, the EMU model is built and run in the TPSS for joint simulation. The availability of the model is verified by combining the harmonic content and voltage level. Then, the distribution of negative sequence current under the no-load, traction and regenerative braking conditions of the system is analyzed in detail, and the negative sequence characteristic waveform under various conditions is obtained, so as to obtain the variation law of negative sequence current under different conditions. Results: Under the regenerative braking condition, the current harmonic distortion is much higher than that under the traction condition. From the analysis of voltage and current phase, the power factor of regenerative braking is also small. In the negative sequence analysis, the tip negative sequence current impact phenomenon occurs mostly during the traction operation of the train, while the current impact effect is weakened during regenerative braking, but the amplitude of the negative sequence fluctuation shows an increasing trend. Conclusion: The energy generated by regenerative braking will be utilized by the locomotive under traction, and these bad electric energies will have extremely adverse effects on the process of high-speed train receiving and changing current. These negative sequence analysis results can be used to identify and classify different working conditions and divide and conquer energy compensation actions to achieve energy saving and consumption reduction.

In the study of harmonic and negative sequence current of high-speed railway traction power supply system, many literatures have the regret of insufficient completeness of simulation system. In this paper, the negative sequence current distribution of the system under no-load, traction and regenerative braking conditions is analyzed in detail from the design of converter to the simulation operation modeling process of EMU. The negative sequence characteristic waveforms under various working conditions are obtained. In addition, the simulation results show that the regenerative braking condition is rich in harmonics, and the generated energy will be used by the locomotive under traction. These poor energy will threaten the current collection and commutation process of high-speed trains. According to the waveform in this paper, the trend of negative sequence current can be summarized and used for the prediction of negative sequence current. The negative sequence current under different working conditions can realize the accurate classification and identification of the working conditions, so as to divide and rule the working conditions, and more reasonably avoid the occurrence of accidents such as generator burning caused by negative sequence problems.

No abstract

A new methodology is proposed in this study for active steering of a tram with independently rotating wheels (IRWs). This methodology has been developed specifically to improve the tram’s steering capability and to reduce wheel-rail wear. The tram is represented by a complex dynamic model with a diverse range of operating conditions, and traditional active steering methods cannot ensure that the tram can remain well-controlled throughout the entire range of operating conditions. The linear parameter-varying (LPV)- H∞ control method proposed in this paper uses variable parameter theory to represent the nonlinearity, the parameter uncertainty, and the external force changes in the IRW. The LPV- H∞ steering controller can not only ensure the robustness of the uncertain system, but also can balance the complexity and the performance of the controller. This allows the tram to offer good steering performance under various running conditions. The simulation results presented in this research show that application of the proposed control method improves the running performance of the tram and reduces the wheel-rail wear significantly on both straight and curved tracks when compared with the passive case.