Elsevier

Journal of Cleaner Production

Volume 212, 1 March 2019, Pages 438-446
Journal of Cleaner Production

Optimization methodology for coasting operating point of high-speed train for reducing power consumption

https://doi.org/10.1016/j.jclepro.2018.12.039Get rights and content

Highlights

  • A dynamic model of PMSM for high-speed train during coasting is established.

  • The influence of the change of load torque on the stable operation domain of high-speed is studied.

  • Under the premise of ensuring the safe operation of high-speed train, an optimization methodology of the coasting point is proposed.

Abstract

As an effective way to reduce power consumption, coasting has been widely used during the operation of high-speed train. However, as a typical electromechanical coupling system, the different speed of inert point may lead to complex dynamic behavior of high-speed train and affect the safety operation. Based on this, this paper proposes an optimization methodology of the coasting point to simultaneously ensure the safety operation and energy saving of the train. A mathematical model of permanent magnet synchronous motor (PMSM) during coasting is established, and the local stability and bifurcation conditions are derived based on Routh-Hurwitz criterion and the bifurcation theory. And the influence of load torque variation on bifurcation characteristics of equilibrium point and stable operation domain of the system is studied. Moreover, detailed numerical simulations are carried out to analyze the effect of load torque on the coasting point, and an optimization methodology is proposed. Experimental platform is set up to verify the correctness and the effectiveness of the proposed optimization methodology. The results show that the variation of the motor parameters may the occurrence of Fold and Hopf bifurcations, and the increase of load torque may change the bifurcation characteristics and lead the system to transit into a chaotic state and lose stability. The experimental results show that the optimization method proposed in this paper can effectively reduce the energy consumption by 7.7 percent.

Introduction

Due to the large volume, fast speed and high efficiency, high-speed train plays an important and ir-replaceable role in the transportation system of many countries (Xing et al., 2015; Sharma et al., 2015). However, compared with other public transportation, high-speed train consumes a lot of energy while pro-viding more convenient and efficient services (Hasegawa et al., 2015; Feng, 2011). Therefore, it is very important for high-speed train to reduce power consumption during the operation. At present, coasting is considered to be one of the most effective energy-saving measures for high-speed trains while operating. between stations (Lin et al., 2017; Wong and Ho, 2004a,b). Therefore, it is of great academic significance and engineering application value to optimize the energy-saving control method for high-speed train during coasting.

Aiming at the problem of energy-saving optimization of the coasting for high-speed train, domestic and foreign scholars have done a lot of in-depth research work. Lin established a multi-particle train model driven by asynchronous motor to optimize a energy consumption curve. Multi-population genetic algorithm was adopted to solve this multi-point combinatorial optimization problem and improve global search capability and convergence speed by parallel optimization (Lin et al., 2017). Hwang presented an approach to identify a fuzzy control model for determining an economical running pattern for a high-speed railway through an optimal compromise between trip time and energy consumption, and the impact of different soft speed limits on energy consumption was explored (Hwang, 1998). Bocharnikov designed a fitness function with variable weightings to balance saving energy and trip time. Energy savings were found, both qualitatively and quantitatively, to be affected by acceleration and braking rates, and the fitness function was used to identify optimal train trajectories (Bocharnikov et al., 2007). Albrecht systematically discussed the mathematical modeling of train operation, the typical optimal control mode, the existence of optimal switching points, and the optimal strategy under speed limitation (Albrecht et al., 2015; Albrecht et al., 2016). Chang applied the genetic algorithm to optimise train movements using appropriate coast control that can be integrated within automatic train operation systems. By calculating the most suitable idle position in the train operation process, the energy consumption is minimized on the basis of ensuring that the train runs smoothly and on time (Chang and Sim, 1997; Acikbas and Soylemez, 2008). Wong presented an application of hierarchical genetic algorithms to identify the number of coasting points required according to the traffic conditions. Single and multiple coasting point control with simple genetic algorithms were developed to attain the solutions and their corresponding train movement is examined (Wong and Ho, 2004a,b). Chuang applied a train performance simulation to solve the energy consumption, and created the data set for artificial neural network (ANN) training accordingly. The ANN model was established and the optimal coasting speed was then derived by performing the ANN training (Chuang et al., 2009). At present, many scholars pay more attention to the impact of the optimization of the coasting point on power conservation, with the aim of achieving the destination with the least power consumption. By summarizing the results of the coasting optimization study, most of them are to increase the speed of the coasting point, prolong the coasting time or increase the number of coastin, and less consideration is given to the operation safety of train idling process. In the course of train operation, safety is the most basic requirement. The traction system of high-speed train is a complex electromechanical coupling system (Liu and Zhu, 2013; Chen et al., 2015; Shanmugasundram et al., 2014), and the change of electromechanical parameters may significantly affect its operation stability. The change of the coasting load torque, ie the coasting speed, may cause the high-speed train to generate complex nonlinear dynamic behavior during coasting, which affects the safe operation of the train. Therefore, it is very meaningful to propose an optimization methodology of the coasting point to simultaneously ensure the safety operation and energy saving of the train.

The remainder of this paper is organized as follows. In Section 2, a mathematical model of PMSM for high-speed train during coasting is established. Section 3 derives the local stability condition and bifurcation condition of PMSM based on Routh-Hurwitz criterion. And the influence of load torque variation on bifurcation characteristics of equilibrium point and stable operation domain of the high-speed train is studied. In Section 4, detailed numerical simulations are carried out to analyze the effect of load torque on the coasting point, and an optimization methodology is proposed. Experimental platform is set up to verify the correctness and the effectiveness of the proposed optimization methodology. The research methods and results of this paper are compared with those of previous study on the high-speed train during coasting in Section 6. Section 7 concludes this paper with final remarks. Before ending this introductory section, it is worthwhile pointing out the main contributions of this paper as follows.

  • 1.

    The mathematical model of the high-speed train during coasting is established, and the influence of the change of load torque on the stable operation domain of the system is studied.

  • 2.

    Under the premise of ensuring the safety operation of high-speed train, an optimization methodology of the coasting point is proposed to save energy consumption of the train.

Section snippets

Model of PMSM for high-speed train during coasting

As a big power consumer, if the high-speed train are always in the driving state during its operation, it may lead to a large amount of power wasted. Therefore, after reaching a certain speed, the high-speed train coasts by its own inertia to save power. In general, the operating mode of a high-speed train is following: accelerating-cruising-coasting-braking, and the schematic structure of high-speed train at coasting condition is shown in Fig. 1.

The mathematical model of PMSM for high-speed

Stability analysis of equilibrium point for high-speed train

To further reveal the stable operation domain of PMSM during coasting, we firstly analyze the influence of parameters γ, σ and T¯L on the equilibrium points. The equations of equilibrium points Eq= (i¯d0i¯q0ω¯0) can be written as{i¯d0+ω¯0i¯q0=0i¯q0ω¯0i¯d0+γω¯0=0σ(i¯q0ω¯0)T¯L=0

Thus the equilibrium point can be expressed as Eq = (ω¯02+ω¯0T¯L/σω¯0+T¯L/σω¯0), where ω¯0 satisfies the following equationω¯03+1σω¯02T¯L+(1γ)ω¯0+1σT¯L=0

The Jacobian matrix of Eq. (3) can be expressed asJ=[1ω¯0i¯q0ω¯

Optimization methodology for coasting point of high-speed train

From the previous analysis, it can be seen that the change of parameters may cause non-smooth bifurcation of the system. Moreover, the variety of load torque may change bifurcation characteristics of equilibrium point and stable operation domain of the system. According to Table .1 and related formulas, the parameter values are calculated as γ=8.3, σ=3.8. From Fig. 2, it can be seen that with T¯L increasing, the area where point P (γ=8.3, σ=3.8) is always changing, from region A to region C,

Experimental facilities

In order to further verify the correctness and effectiveness of the proposed optimization methodology, the 600 kW PMSM test bench is established as shown in Fig. 4, Fig. 5. Fig. 4 shows that the test bench involves two parts, namely the hardware and software. The hardware includes the power battery, PMSM, eddy current dynamometer, current sensor and speed sensor, where the power battery provides high-voltage power for the PMSM, and the PMSM is used to simulates the states of the motor in a real

Discussion

On the premise of guaranteeing the stable operation of high-speed train, this paper studies the influence of the variation of load torque on the stable operation domain of the system, and proposes an optimization methodology of optimal idling point to reduce power consumption. It is found that the change of motor parameters may cause the equilibrium points to generate Fold bifurcation and Hopf bifurcation. These two kinds of bifurcation divide the operation domain of the system into three

Conclusion

In this paper, a mathematical model of PMSM at coasting condition is established, and research work was carried out on the problem of energy-saving optimization of the coasting for high-speed train. The following conclusions are obtained:

  • (1)

    The change of motor parameters may cause the equilibrium points to generate Fold bifurcation and Hopf bifurcation, dividing the operation domain of the system into three categories: absolutely stable domain, progressively stable domain, and chaotic domain.

  • (2)

    The

Conflicts of interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

Acknowledgements

This research is supported by the National Natural Science Foundation of China (51705208) and China Postdoctoral Science Foundation (2018M632240).

References (20)

  • A. Albrecht et al.

    The key principles of optimal train control-Part 1: formulation of the model, strategies of optimal type, evolutionary lines, location of optimal switching points

    Transp. Res. Part B Methodol.

    (2016)
  • S. Acikbas et al.

    Coastig point optimisation for mass rail transit lines using artificial neural networks and genetic algorithms

    IET Electr. Power Appl.

    (2008)
  • A. Albrecht et al.

    The key principles of optimal train control-Part 2: existence of an optimal strategy, the local energy minimization principle, uniqueness, computational techniques

    Transp. Res. Part B Methodol.

    (2015)
  • Y.V. Bocharnikov et al.

    Optimal driving strategy for traction energy saving on DC suburban railways

    IET Electr. Power Appl.

    (2007)
  • C.S. Chang et al.

    Optimising train movements through coast control using genetic algorithms

    IEE Proc. Elec. Power Appl.

    (1997)
  • X. Chen et al.

    Nonlinear vibration for PMSM used in HEV considering mechanical and magnetic coupling effects

    Nonlinear Dynam.

    (2015)
  • H.J. Chuang et al.

    Design of optimal coasting speed for MRT systems using ANN models

    IEEE Trans. Ind. Appl.

    (2009)
  • H.B. Cui et al.

    Influence of braking efficiency on high-speed train energy-saving driving strategies

    J. China Railw. Soc.

    (2012)
  • X. Feng

    Optimization of Target Speeds of High-speed Railway Trains for Traction Energy Saving and Transport Efficiency Improvement

    (2011)
  • D. Hasegawa et al.

    Standardised approach to energy consumption calculations for high-speed rail

    IET Electr. Syst. Transp.

    (2015)
There are more references available in the full text version of this article.

Cited by (11)

  • Enhancing heat dissipation to improve efficiency of two-stage electric air compressor for fuel cell vehicle

    2022, Energy Conversion and Management
    Citation Excerpt :

    The efficiency of the TSEAC is improved under the same compression degree, the efficiency improvement is more obvious at high speed and high pressure ratio. With the wide application of high-power PEMFC, the TSEAC is developed towards the trend of high speed and high pressure ratio [27,28]. Enhancing heat dissipation of its shell will bring a better energy saving effect.

  • Optimization of speed response of super-high-speed electric air compressor for hydrogen fuel cell vehicle considering the transient current

    2021, International Journal of Hydrogen Energy
    Citation Excerpt :

    Under the guidance of the global automotive environment, hydrogen fuel cell vehicle develops rapidly due to its advantages of zero pollution, low energy consumption, long-range. The high-power fuel cell has become a current research hotspot [1–3]. At present, the fuel cell air compressor is the most core key component except the fuel cell electric reactor, which provides air under specific temperature, pressure, and flow conditions [4,5].

  • Optimal operation region of super-high-speed electrical air compressor in fuel cell system for working stability under multiple-time scale excitation

    2021, International Journal of Hydrogen Energy
    Citation Excerpt :

    The stability of a super-high-speed permanent magnet synchronous motor(SHSPMSM) significantly determines the energy efficiency and operation performance of a fuel cell. Nonlinear vibration can result in instability of the system or even cause damage to the electromechanical components of the system [12,24,25]. Aouzellag H et al. [13] took FC/HC HEV as the research object, a fault-tolerant strategy is set between two five phase permanent magnet synchronous motors (PMSMs) to reduce torque fluctuation and power vibration.

  • Timing choice and catch-up strategy for latecomers in emerging green technologies: An exploration study on China's high-speed rail industry

    2020, Journal of Cleaner Production
    Citation Excerpt :

    This section presents the research findings, theoretical contributions, practical implications, limitations and outlook. In the knowledge-based economy era, emerging green technologies have been regarded as the main driving force of cleaner production, environmental protection, industrial restructuring, and economic growth (Hu et al., 2019). To develop strategic competitive advantage in the new round of international competition, numerous emerging countries are encouraging their firms to catch up with forerunners in the field of emerging green technologies.

View all citing articles on Scopus
View full text