Research And Application Of Mobile Energy Storage Emergency Power System

With the development of information technology,more and more power electronic devices are applied to people's daily life,and user demand for reliability of power supply becomes higher and higher.For some important meetings,contest and precision equipment processing plants,once the distribution line is cut off for a short time,it will cause significant political and economic losses.For the uninterrupted power supply of these lines,it is very important to study the technology of uninterrupted power supply for key lines.At present,most of the emergency power supply devices which are mainly diesel engine power generation are used for guaranteeing power supply in the key line.The main disadvantages of these devices are high pollution and noise.The adjustment time from start to stable output of electric energy is too long,so it is difficult to realize the uninterrupted guaranteed power supply.Therefore,based on the On-line UPS structure,this paper proposes a mobile emergency power supply system which combines the electric power and the energy storage battery to realize pollution-free and uninterrupted power supply.Firstly,by analyzing the characteristics and investment benefits of several commonly used energy storage batteries,the lithium iron phosphate battery is selected as the emergency power storage system.According to the characteristics of lithium battery Thevenin circuit,the mathematical model of lithium battery is established.In order to ensure the safety of energy storage batteries' charge and discharge,three-stage charge and working range which is based on batteries' state of charge(SOC)are proposed,and control scheme of the overall charge and discharge in energy storage battery is designed.Secondly,determine the topology of the mobile energy storage emergency power supply system.Considering that the mobile energy storage power supply system in the project needs to be easy to operate and the energy storage battery can adjust the system power in real time,the mains side converter uses constant power control(PQ control).The load-side converter directly supplies power to the load,and uses constant voltage and frequency control(VF control)to ensure that the system provides stable and high-quality power.Based on the above analysis,taking the mains-side converter as an example,a mathematical model of the converter is established,and the corresponding coordinate transformation is performed to design the power outer-loop / current inner-loop control circuit for the mains-side converter,and the load-side converter voltage Outer loop / current inner loop control circuit,and design its circuit parameters and PI parameters.At the same time,simulation verification of the proposed control strategy proves that the control systems designed for different converters meet the requirements.Then,the simulation model of the mobile energy storage emergency power supply system is established,and the energy management and coordinated control method based on the system power balance is designed.The energy management control methods of the emergency power supply system under mains operation,mains failure and comprehensive mode are analyzed in detail.The accuracy of the model and the effectiveness of the control strategy are verified through simulation.Finally,according to the mobile energy storage emergency power supply system engineering requirements,the overall frame structure of the mobile energy storage emergency power supply vehicle,the main circuit parameters of the power converter unit and the energy storage battery system grouping scheme are designed.Through the field test of the mobile energy storage emergency power supply vehicle,the overall working effect was verified.