| The rapid development of urban rail transit has also become a major energy consumer in the power grid.In order to ease the pressure on urban rail system power supply and promote energy conservation and emission reduction,the introduction of new energy has become an effective measure and has been initially applied.With the improvement of China’s solar power generation technology and national policy support,PV(photovoltaic)has outstanding advantages and will be an important part of the future rail transportation application of renewable energy.Due to the large fluctuation of locomotive load and a large amount of regenerative braking energy,the PV power supply system connected to the urban rail traction needs to introduce energy storage(ES)system to balance energy distribution and suppress sharp changes in network pressure.At present,the research on the integration of PV/ES into urban rail transit systems is in the preliminary exploration stage,and large-scale systematically access is still facing challenges.To this end,this article has done the following research:First,the operating characteristics of PV power supply system connected to urban rail transit are analyzed.Matlab/Simulink simulation model of urban rail power supply system is built,and harmonic and reactive power analysis are performed.The basic principles of PV are introduced and a simulation model is introduced.In order to explore the impact on the power quality of urban rail system after PV access,the PV is connected to the AC 35 k V side of the main substation and the AC 400 V side of the step-down substation for simulation analysis;In order to reduce the power factor of the grid-connected point caused by large-capacity PV access,the inverter control strategy has been improved,which enables the inverter to output certain reactive power to improve the power factor.Then,the research on the PV/ES system connected to the urban rail DC traction power supply system is conducted.A mathematical model for substation load is established based on the traction calculation data of a single train,which is combined with the regenerative feedback device simulation to simulate the power-voltage change of the traction network.By comparing the energy saving and PV utilization before and after ES system access,the necessity of ES system access was verified,and an energy management strategy using the QPSO algorithm to optimize charging and discharging time of ES is proposed,which can improve the recovery rate of locomotive regenerative braking energy by the new energy system.On the basis of the original ES power control strategy,voltage control based on fuzzy control is introduced.The voltage control strategy of PID achieves the stability of the grid-connected voltage under the control of energy distribution.Finally,a full life cycle economic model of the PV/ES system access to the traction power supply system is established,and the profit model under the operation model of different stakeholders is discussed.The effects of simultaneous changes in costs and subsidies,charging and discharging efficiency of ES,and borrowing methods on economic benefits are analyzed.In order to optimize the allocation of PV/ES capacity,the capacity allocation methods in different modes are proposed respectively.Taking into account the single stakeholder,the optimization is aimed at the lowest total cost and the highest total PV/ES power consumption,and obtains a compromise solution through fuzzy theory;Under the consideration of different stakeholder models,the PV/ES capacity recommendation scheme is obtained through scheme comparison and data analysis,the relevant research results can be used as a reference for project investors. |
PDF Full Text Request