| Since China entered the new era,society,economy and culture have maintain sustained and fast growth,but in the meantime,due to the limited storage of traditional energy,energy supply is insufficient,which has become the main reason that limits the social development of human being.So far,China’s national railway and urban rail transit is still mainly electrified railway,as a large energy consumption of power system,rail transit industry also has environmental pollution and high energy consumption and other problems.For the purpose of vigorously boosting the continuance development of Chinese rail transit,the development of environmentally friendly,high-efficiency new energy rail vehicles have significant social benefits and huge potential economic benefits.As a kind of renewable energy with high efficiency and environmental protection,hydrogen energy has become a sally port of promoting a green economy in the transport field,and has been widely concerned by many countries.Hydrogen power intercity EMU uses fuel cell as the main power source and energy storage system as the auxiliary power source,which no longer needs to obtain energy from catenary,providing a new idea for the development of rail transit industry.Firstly,the types,advantages and disadvantages of commonly used energy sources and energy storage devices such as fuel cells,batteries and ultracapacitors are compared and analyzed.According to the actual needs and characteristics of intercity EMUS,the topology of hybrid power system is analyzed and designed,and the active dual-hybrid topology with fuel cell as main power supply and lithium battery as energy storage is finally determined.The fuel cell hybrid power system model for intercity EMUS was built through Simulink platform,including fuel cell power generation system,lithium battery system,unidirectional DC/DC converter and bidirectional DC/DC converter,which laid a foundation for the following system capacity configuration and energy management.Secondly,the selection of fuel cell and battery is determined.Based on the main technical parameters of CRH6 F intercity EMUS,the dynamic model of intercity EMUS is established.The traction calculation of the main dynamic performance indexes of intercity EMUS is carried out combined with the operating conditions.Combined with the traction and braking characteristics of EMU and the circuit information,the dc bus power demand of the vehicle under a complete operating condition is obtained.Considering EMU dynamic performance,system quality,power density and other indicators,the capacity configuration of the intercity EMU power system was carried out by using the fish swarm intelligence optimization algorithm,and finally the configuration scheme of the hybrid power system was obtained.Finally,based on the hybrid power system model and capacity configuration scheme,the Pontryagin Minimum Principle(PMP)was introduced to minimize the equivalent hydrogen consumption and consider the life loss of the power supply.An improved PMP was proposed to realize the energy distribution of the hybrid power system.An efficient and reliable coordinated control method for fuel cell power generation system based on hierarchical coordinated control is proposed.On the basis of top level energy management,the droop coefficient of power supply is adjusted to drive the power distribution of bottom level coordinated control system.The plug and play performance of droop control is analyzed by simulating power supply failure.The power supply reliability of the layered energy management method is analyzed by simulating the failure of the top-level energy management.The effective power distribution of multi-source power system under decentralized control framework is realized.It is proved that the layered energy management method can keep the stability of the system when one set of fuel cell fails or the top layer energy management fails.Even if the communication fails in a short period of time,the load power can still be distributed properly and the power supply reliability of the hybrid system can be improved. |
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