| Chinese electrified railway has the characteristics of long operating mileage,high passenger and freight volume,and high electrification rate.With the growth of electrified railway mileage and transportation volume,the energy consumption of traction power supply system(TPSS)has also increased,which has become increasingly severe.Therefore,the energy-saving and efficient operation of electrified railways is an urgent problem in its rapid development.In recent years,many studies indicate that recycling the regenerative braking energy(RBE)of trains returned to the power grid by the TPSS is one of the most effective ways to achieve energy-saving and efficiency improvement in electrified railways.However,realizing the efficient utilization of RBE for electrified railways faces the following challenges: 1)It is difficult to analyze the load characteristic of electrified railways under complex operating conditions accurately;2)The lack of efficient RBE utilization methods;3)How to balance the technical effect and economy of the RBE utilization.The challenges mentioned above are also the keys for research on the RBE utilization in electrified railways.Based on the above background and challenges,this thesis focuses on the RBE utilization in electrified railways,including the analysis of load characteristic,design and optimization of RBE utilization system,and development of design and verification platform for RBE utilization system.The research work of the thesis mainly includes the following five aspects:(1)The load characteristic of electrified railways was studied.Based on the field measured data,the load characteristics of the electrified railway was analyzed from three levels,including train(single train),traction substation(single substation)and electrified railway line(multiple substations).On this basis,the load characteristics were qualitatively evaluated to provide guidance for the research on the RBE utilization in electrified railways by considering the measured load data of different types of electrified railways.(2)An energy storage-based RBE utilization system and its control strategy for traction substation were studied.Combining the topology of TPSS and the load characteristics of traction substation,a railway power conditioner-based RBE utilization system integrates with the energy storage was studied,and its operation principle was deeply analyzed.Meanwhile,the operating modes of the RBE utilization system were analyzed by considering load operating conditions of the TPSS.Further,combined with the topology and operation principle of the RBE utilization system,its control objectives were analyzed,then a master-slave control strategy with a central controller was proposed to realize the operation mode management and power flow control of the RBE utilization system.Finally,simulation,experiment,and field load data-based evaluation comprehensively verified the energy-saving effect of the proposed RBE utilization system,achieving the efficient RBE utilization of the traction substation.(3)The multi-substation cooperation-based integrated RBE utilization system and its control strategy for electrified railways was studied.Combining the distributed characteristics of electrified railway traction substations and the strong complementarity of the load power in adjacent traction substations,the multi-substation cooperation-based integrated RBE utilization system was studied,and its operating modes were discussed based on its operating principle and the operating conditions of adjacent traction substations.On this basis,a hierarchical control strategy was proposed to realize the centralized management of operation mode and active power flow,as well as the decentralized control of system power flow,and the impact of communication on the control strategy was analyzed.Hardware-in-the-loop-based simulation and field load data-based evaluation results validated that the integrated regenerative braking energy system effectively improved the RBE utilization through power delivery and energy storage between adjacent traction substations,and the power quality issues were also suppressed.In addition,the comparison analysis proves the advantages of the integrated RBE utilization system in terms of technical effects and economy.(4)The techno-economic model-based method of optimal capacity configuration for the RBE utilization system was studied.According to the relationship between the technical effect and economy of the RBE utilization system,the techno-economic model was built by considering its comprehensive power flow control ability in RBE utilization and power quality suppression,and metrics of the model were analyzed.On this basis,the method of optimal capacity configuration for the RBE utilization system was studied,which takes the RBE utilization rate and power quality standards as the technical metrics and the lifetime economy as the economic metric.Field load data-based case study and simulation results verified the correctness and effectiveness of the proposed capacity configuration method.(5)A simulation and experiment platform of the RBE utilization system for electrified railways was developed.In response to the requirements of design and verification for the RBE utilization system in the research and applications,the functional requirements of the platform for the RBE utilization system were deeply analyzed,and then the platform architecture was formulated.On this basis,a simulation and experiment platform of the RBE utilization system for electrified railways was developed based on the theoretical research results,including the following functions,i.e.,load characteristics analysis of electrified railways,design of RBE utilization system,verification of RBE utilization system,evaluation of RBE utilization system.Finally,the application method of the platform for RBE utilization system was introduced,and its effectiveness was verified based on relevant case studies.This thesis about the research on the RBE utilization in electrified railways is based on the load characteristic of the electrified railways,which forms the theoretical achievements from the aspects of RBE utilization system and its control strategy for different types of electrified railways,and the method of optimal capacity configuration for the RBE utilization system.Based on the above theoretical research,a simulation and experiment-based platform is developed by considering the design and verification requirements of the RBE utilization system in research and applications.The relevant research results in this thesis have addressed the key theoretical and application issues in the research on RBE utilization of electrified railway,which lays a foundation for the practical application of RBE utilization system in electrified railways. |
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