Simulation And Optimization Design Of Wayside Energy Storage System In Urban Railway

China’s urban rail transit construction has begun to take shape,and is still developing rapidly,the construction volume is becoming increasingly large,and the related technology is becoming mature.There are still problems of low profit rate and high system energy consumption in urban rail transit.Regenerative braking energy recycling has been proved to be an effective response.The regenerative braking energy recovery and utilization technology mainly includes braking resistors,inverter devices and energy storage system(ESS).ESS can store the electric energy of the train braking process in the energy storage medium,and release the stored energy during the train traction,which has less impact on the medium voltage power grid.At the same time,the response speed of ESS is fast,which can reduce the voltage fluctuation of the traction network and alleviate the rail potential problem.The equivalent circuit model of urban rail DC traction power supply system including rectifier unit,train and traction network is established.On the premise of considering the accuracy and efficiency of the model,the power model of on-board braking resistor considering duty cycle is established,and the effectiveness of the model is verified by the measured data.According to the black box external characteristic model of ESS in the international standard,the external characteristic model of the traction substation in which the ESS and the rectifier unit work together is established.At the same time,the peak power correction of ESS is considered under the limitation of duty cycle and residual power.The equivalent circuit diagram and solution algorithm of urban rail power supply system under different working conditions are proposed.A multi state switching algorithm of traction substation based on bang bang control theory is designed to optimize the speed and convergence of state iteration.A double-layer iterative algorithm is proposed to solve the DC traction power supply system considering wayside ESS.Four evaluation indexes are proposed to comprehensively evaluate the operation effect of the ESS from two aspects of energy saving and voltage stabilization.The effectiveness of the algorithm is verified by comparing the simulation and measured data of the actual urban rail transit,and the operation of the system under different departure intervals and different parameters of the ESS is analyzed.The location and capacity determination method for ESS based on regenerative braking energy distribution and an optimization algorithm for ESS based on NSGA-II are proposed.The former is suitable for the preliminary planning and rough estimation of site selection and capacity determination scheme,while the latter is suitable for the overall scheme optimization design of various complex systems.According to the situation of fixed budget and sufficient budget,different scheme selection modes are put forward.NSGA-II has good adaptability,and the distribution of each feasible solution in Pareto solution set is relatively uniform,which is convenient to select the appropriate final configuration scheme for different situations.