| Contemporary society has entered the era of convenient transportation,and people’s travel is being made more convenient and efficient via urban railway.In response to the call for national energy conservation and emission reduction,urban rail regenerative braking energy utilization technology is come into being.The increase in the utilization rate of regenerative braking is the trend of the development of urban rail transit.Inverter feedback technology has become a hot research topic for experts and scholars because of its high efficiency,energy saving and high cost performance.For the traction power supply system with inverter feedback device,the optimization design and energy-saving effect evaluation are urgent problems to be solved,and the power supply calculation of the urban track inverter feedback device plays an important role in solving the above problems.Therefore,the power flow calculation of the urban rail traction power supply system with inverter feedback device,the capacity optimization design of the inverter feedback system and the energy saving effect evaluation of the inverter feedback system are studied in the paper.In this paper,the structure of urban rail power supply system is first introduced,and the characteristics of the rectifying unit considering the internal resistance of different operating sections,namely the multi-line model and the power flow calculation model is analyzed.In addition,the modeling of traction nets and trains in urban rail power supply systems is studied.The realization of the next urban rail AC/DC power supply calculation algorithm is based on the modeling of urban rail transit power supply system.Based on the model of the traction substation in the rectified state,the state of the traction substation added to the inverter feedback device is studied and analyzed.By establishing the power supply calculation model under the modes of turn-off,Inverter voltage regulator and inverter full load,a multi-state soft handoff algorithm based on Bang-Bang control for traction substation is proposed.The fluctuation of traction network pressure,and different control strategies of the inverter feedback device under different working conditions of change and traction substation are considered.Using the algorithm to develop the urban rail power supply system simulation platform,combined with the example of Chongqing Rail Transit Line 9 project,the convergence precision and convergence speed of the algorithm are analyzed at different time intervals of different departure intervals,and the feasibility of the algorithm is verified.For the traction power supply system of the inverter feedback device installed on the whole line,the multi-state switching process of the traction substation is analyzed at a certain time,and the effectiveness of the algorithm is verified.The algorithm is used to compare the reference system and the whole line.The traction network pressure and the rail potential change of the inverter feedback system are installed.The influence of the inverter feedback device on the traction network voltage and the rail potential of the power supply system is analyzed.Different design schemes are proposed for the capacity of the medium and low voltage inverter feedback device of the inverter feedback system.For medium voltage inverter feedback,the capacity of the medium voltage inverter feedback device is determined by the effective value and average value of the feedback power during the continuous working time in the intermittent working system of the device;for the low voltage inverter feedback,the inverter feedback device is fixed according to the distribution transformer and its load,and the ground braking system determines the capacity according to the peak value of the feedback power.Based on the power supply simulation platform developed by the Bang-Bang control based multi-state soft handoff algorithm based on Bang-Bang control,the simulation study of Chongqing Rail Transit Line 9 is recommended for the low-voltage inverter feedback device of each traction substation.Installation capacity.The evaluation of energy-saving effects of inverter feedback systems has always been a hot topic of concern and research.For the traction power supply system with inverter feedback device,the utilization of regenerative braking energy of trains at different departure intervals and the full-day driving plan are considered,and energy-saving effect evaluation indexes of the system daily feedback energy,main reverse rate,regenerative braking energy feedback rate and system-level energy saving rate are proposed.Combined with the actual subway project,the energy-saving effect of the urban rail inverter feedback system is quantitatively analyzed and evaluated from the starting voltage of the inverter feedback device and the power load rate of the whole line.This index has guiding significance for how to evaluate energy-saving indicators and how to optimize the design of power supply systems when the inverter feedback device is widely used in rail transit lines. |
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