Optimal Algorithm of Tram Section Energy-saving Speed Curve under Fixed Time Constraint

Abstract

Objective Calculation of tram operation control scheme taking into account energy consumption requires a great deal of calculation of the energy-saving speed profile. In order to establish an accurate and efficient optimal model for the energy-saving speed curve of tram sections, it is necessary to study the optimal algorithm of the energy-saving speed curve based on time-step search and under time-fixed constraints while considering the tram characteristics of low speed, short section and fewer long steep slopes. Method On the basis of implementing basic ergodic search, the search range of the feasible solution is narrowed down by boundary analysis. Under the condition that the tram acceleration duration is given, an optimized energy-saving algorithm based on fixed acceleration duration is proposed to avoid unnecessary braking in steep downhill section, and a dichotomy method is used to expedite the search.When the tram acceleration duration is not fixed, under the premise of no additional braking during the tram cruise and coasting, an improved search method based on being sensitive to energy consumption change is proposed, which is helpful to determine the optimal acceleration time quickly. Result & Conclusion Compared with the existing numerical analysis method, the proposed algorithm based on time-step search replaces the complex integration process,simplifying the computational process.The test data shows that the algorithm takes less than 1ms to finish a single operation in a typical tram operation section,and greatly improves the calculation speed compared with the conventional genetic algorithm. The algorithm can adjust the calculation precision and speed index by changing the time step size, and can serve as the basic algorithm of energy-saving calculation for tram lines.

Keywords

• tram
• energy saving
• speed curve optimization
• dichotomy