| In recent years,China urban rail transit has developed rapidly,At the end of 2020,the operating mileage of urban rail transit in mainland China has reached 7978.19 km.However,with the rapid expansion of urban rail transit,the energy consumption problem that comes with it has become increasingly prominent.Take the Beijing Subway as an example,the total power consumption in 2019 reached more than 2 billion k Wh.In order to reduce the energy consumption of train operation,energy storage devices such as super capacitors,lithium batteries and flywheels has been used to absorb regenerative braking energy.Because super capacitors have the advantages of high power density and long cycle life,wayside super capacitor energy storage systems(SCESS)are increasingly widely used in urban rail transit at home and abroad.However,in practical applications,it is found that the SCESS has a slow dynamic response speed under certain working conditions and voltage oscillation of traction network when the traction power is large during train operation.This paper takes the bidirectional DC/DC converter of the wayside SCESS as the research object,and solves the above problems by optimizing the control strategy of the converter.In this paper,a small signal model including the SCESS and the train is first established,and the influence of the train current and the duty cycle of the DC/DC converter on the dynamic performance of the SCESS is analyzed.In order to improve the dynamic performance of the SCESS under different steady-state operating points,a double loop control strategy based on active disturbance rejection control(ADRC)is proposed.Firstly,an ADRC controller is designed,to solve the problem that the parameters of ADRC controller are too many and difficult to adjust,objective function is designed,use the genetic algorithm(GA)to optimize the parameters of the controller under different steady-state operating points,and then use the least square method to fit the optimization results,realize the real-time optimal adjustment of the controller parameters.The effectiveness of the method is verified by simulation and experiment.When the SCESS is connected to the traction power supply system,the hardware parameters,the negative impedance characteristics of the constant power load and the state of SCESS will all have an impact on the stability of the system.In this paper,a single station,single train and single SCESS model is used as the analysis object,and the factors affecting system stability are analyzed.In order to solve the problem of voltage oscillation caused by the negative impedance characteristic of the train as a constant power load,a controller based on the ADRC and passive based control(PBC)is designed.The effect of the oscillation suppression strategy was verified by simulation and experiment.Finally,an SCESS experimental platform and a hardware-in-loop experimental platform of urban rail transit traction power supply system with SCESS were built,based on the two platforms,achieved the comparative analysis of the control effect between the control strategy proposed in this paper and the PI control,and the effectiveness of the converter control strategy proposed in this paper is verified. |
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