Distributed Energy Storage Bidirectional DC/DC Converter And SOC Equalization Control

With the intensification of energy and environmental problems,the application of new energy power generation has developed rapidly.However,due to the impact of natural environment,the new energy generation has the disadvantages of randomness and intermittence,which affect the stable operation of DC bus.As an integral part of DC microgrid,distributed energy storage system plays an important role in suppressing energy fluctuation and maintaining power balance.In order to improve the reliability of energy storage system,this paper will focus on the control strategy of energy storage module.The Floating-output Interleaved-input Bidirectional Converter(FIBC)is selected as the connection between the battery and the DC bus in the distributed energy storage system in this paper.According to the driving waveform of the switch tube,the working principle of the topology is briefly described,and the working characteristics of the voltage gain and current ripple are analyzed in detail.The double closed-loop control principle of the topology is introduced,and the regulator parameters are designed.The State-of-Charge(SOC)of each energy storage module is different.In order to ensure the stable operation of the energy storage system,the control strategy of the energy storage module in two modes of interconnection communication and non interconnection communication is studied in detail in this paper.In the droop control without interconnection communication,based on the exponential SOC droop control strategy,by adjusting the value of n in the power response phase of the system,the response speed of the system can be accelerated on the premise of ensuring the power convergence speed,so as to take into account the speediness of the power response phase and the convergence phase in the process of system regulation,improve the system performance and speed up the SOC balance between the energy storage modules.In the droop control based on internet communication,a new functional relationship between the droop coefficient and SOC is established by introducing the variation coefficient on the basis of SOC droop control,which limits the output power of each energy storage module within its rated range,and speeds up the overall convergence speed of the system,so that the SOC of each energy storage module tends to be balanced faster.Finally,on the basis of theoretical analysis and simulation,the experimental platform of the energy storage module with FIBC as the connection port is built in this paper,and the improved control strategy is adopted to control the output power of energy storage module.The correctness and effectiveness of the improved control strategy are verified by the analysis of the experimental results.