Research On Metro Timetable Optimization Model And Algorithm Based On Regenerative Braking

With the development of economics and acceleration of urbanization, there has been a boom in the development of rail transit, resulting in continuous increasing in train energy consumption. How to reduce the energy consumption of the rapid transit has received increased attention. As regenerative braking acts as a main factor affecting train energy consumption, it has a great importance for energy-saving emission reduction and sustainable development to investigate optimal method of using regenerative braking energy. To avoid the disadvantages of the current utilization pattern of regenerative braking energy, a new strategy was proposed, in which the regenerative braking energy generated by the braking trains could be utilized by the accelerating trains immediately. It will not only prevent the voltage of power supply system from the affection when braking energy fed back to the contact line, but also cut the loss during transmission. The main contents are summarized as follows.Based on the new utilization pattern of regenerative braking energy, the relative location and operation between the adjacent trains were studied, and an optimization model of the metro timetable was built, which was a nonlinear integer programming problem with constraints. Hereto, a simulated annealing algorithm was put forward to solve the problem, and Island Line of MTR was taken as an example. The results showed that the percentage of the utilization had increased between4.7%and11.4%.The optimized timetable may result in long waiting time for the passengers on stations. So taking passenger-time as an indicator of passengers’satisfaction, in which the passenger numbers getting on or off stations were fuzzy parameters, and overlapping time as an indicator of the utilization of regenerative braking energy, a multi-objective optimization function with fuzzy variables was established. Taking Island Line as an example, the optimized timetable can increase the overlap time by48.8%than the current one, and shorten the waiting time by4.3%at the same time.Minimizing the headway can raise the utilization of regenerative braking energy, but it increase train numbers per hour as well, which will lead to an increase in the total energy consumption. Thus, based on the optimal operating method, a global energy consumption optimization model was proposed, together with the regenerative energy matching table and method. In order to validate the model, Yizhuang line was taken as an example. The results showed that the energy consumption per hour decreased dramatically after optimizing. The train accelerating time at each interval and the headways between adjacent trains were calculated, and the optimal train diagram was given.