Research On Energy Storage Battery Simulation System Based On PWM Rectifier

Energy storage technologies,especially large-scale and large-capacity energy storage technologies,are key technologies for solving the difficulties of grid connection due to the inherent random volatility of renewable energy in modern power systems.In recent years,the rapid development of the electric vehicle industry has also puts forward new requirements for energy storage technology.However,in the process of energy storage system and electric vehicle research,the battery pack has many inconveniences such as long charging and discharging times,inflexible battery parameter configuration.Generally speaking,experiments with real battery packs often takes time and would be expensive.Improper use may cause permanent damage to the experimental equipment as well as the battery packs itself.Therefore,if a general-purpose battery emulator can be developed which related experiments can be performed on will be very significant.Main work and chapter arrangement of this paper are summarized as follows:The first part of this paper introduces the application background of the battery emulator and the research status at home and abroad,then the shortcoming of the existing battery emulator is put forward,after that the battery model,which is one of the core of the battery emulator,is sorted and analyzed,the changes of voltage,current and SOC parameters in each model are studied and the application scenes are discussed.The general battery model and the Third Order equivalent model are selected as the internal calculation model of the battery emulator after simulating the discharge characteristic curve of the battery under each model and comparing with the discharge characteristic curve of the real battery.In the second part of this paper,the working principle of the battery emulator is introduced,selected topological structure of the battery emulator according to the requirement of wide voltage output range in DC side of the battery emulator,then the T-shaped three-level is selected as the main power unit of the battery simulation,and the mathematic model of the three-level PWM rectifier and the DC-side voltage control rate are analyzed and established.The mathematic model and DC side voltage control strategy of three-level PWM rectifier are analyzed and established,finally,the software flow and algorithm design of the battery emulator are introduced,and the function of the battery emulator is achieved with the PWM rectifier as the Energy conversion Unit,the battery emulator has the features of easily select the battery type,arbitrarily configure the battery capacity,flexibly adjust the battery SOC state and simulate the temperature characteristic of the battery.At the same time,the management system of the emulator is designed and implemented in order to facilitate the monitoring and management the running state of the battery storage system.The battery voltage,current,SOC and other state can be real-time showed on the storage battery management system,and storage battery management system remind the staff when the battery is in critical charge and discharge state,and equipped with the storage battery emulator configuration function,saved a lot of money and precious time for scientific research.Finally,the paper described the design and construction of the experimental platform,and completed the dynamic and steady-state experiments of the battery emulator,the experiment also verified that the temperature will influence the performance of the battery,at the last,the error analysis of the output voltage of the battery emulator is done,the correctness and practicability of the design of the battery emulator are proved.