Research On Main Protection Algorithm Of Metro Feeder Based On Energy Flow

Urban transportation is the lifeline of urban economic and social development.At present,most central cities in China are facing the problem of road traffic congestion,and the metro with the advantages of large capacity,fast speed,threedimensional and green environmental protection has become the first choice to solve this problem.The “green” advantage of the metro is mainly due to electric traction,and the role of the subway traction network is to continuously supply electric energy to the rail vehicles.The permanent short circuit of the traction network is extremely threatening and has no backup.This imposes extremely high requirements on the traction feeder protection.It is necessary to build a protection algorithm based on the only electrical characteristics of the DC system,and to protect the algorithm in milliseconds.Make accurate fault decisions during the time.Therefore,it is essential to improve the main operation of the metro traction network through theoretical research and technical analysis to ensure the safety of the metro.The main protection of the DC traction network is based on DDL protection and high current trip protection of current characteristics.The sharp increase of traffic load and the application of a large number of new technologies and new equipments have complicated the system state,and it is impossible to accurately determine the current characteristics only.system status.In order to solve the problem of protection malfunction caused by locomotive starting condition and system divergence oscillation,the application of the energy flow theory that best reflects the essential characteristics is used to construct a new subway feeder main protection algorithm.Taking the DC traction power supply system of EMU as the research object,the paper introduces the energy flow theory to develop the new feeder main protection algorithm.Firstly,the system composition and operation characteristics of the DC traction power supply system and the existing main protection of the metro feeder are analyzed.Secondly,according to the basic principle of each part of the DC traction power supply system,a DC traction power supply system model considering the EMU is built on the RTplus real-time digital simulation platform.Thirdly,according to the energy flow theory,the difference of energy flow characteristics between locomotive starting condition,system divergent oscillation and traction network fault state is compared and analyzed.The main protection algorithm of metro feeder based on energy flow is proposed and the tuning method is given.Finally,in order to verify the new algorithm,the RTplus relay protection real-time digital simulation test system and the KF1300 feeder protection device are used to build a semi-physical algorithm test platform.By comparing the data running results,it is proved that the new algorithm can accurately determine the system running state,and it is both reliable and sensitive.In summary,the main protection algorithm of the subway feeder based on energy flow not only has the advantages of high reliability and high sensitivity,but also fits the actual needs of the engineering,and has carried out innovative development in theory.This has theoretical guiding significance for the future development of the main protection algorithm for subway feeders.