重庆理工大学学报2024，Vol.38Issue(23)：173-181,9.DOI:10.3969/j.issn.1674-8425(z).2024.12.021
分布式多储能的孤岛直流微电网SOC均衡控制策略
SOC balancing control strategy for distributed multiple energy storage in isolated DC microgrid
摘要
Abstract
With the growing popularity of renewable energy,DC microgrids have garnered great academic interest from both home and abroad due to their effectiveness in tackling such issues as reactive power and harmonics.However,intermittent and fluctuating characteristics exhibited by renewable energy sources like wind and solar power may cause substantial fluctuations in system power and bus voltage,thereby posing serious challenges to the safe and stable operation of DC microgrids.To address the problem,multiple distributed energy storage units(DESUs)have emerged as prominent control strategies.Nevertheless,when multiple distributed energy storage systems operate in parallel,discrepancies in initial state of charge(SOC)among DESUs along with mismatched line resistances may induce voltage deviations on the DC bus and uneven charge distribution among units,leading to excessive charging/discharging for certain storage units that ultimately shortens their lifespan while adversely affecting the overall safety and stability of the system. We propose an improved SOC balancing control strategy to address the issues of initial SOC inconsistency,mismatched line resistance leading to SOC imbalance,and DC bus voltage offset in DESUs.First,the SOC of distributed energy storage units is combined with exponential and inverse tangent functions to adaptively adjust the P-U droop coefficient,ensuring stable operation of the system and improving the speed of SOC balancing for distributed energy storage units.Second,a state factor related to converter output voltage,power and droop coefficient information is designed.The average values are estimated based on a dynamic consensus algorithm and transmitted between adjacent converters through low-bandwidth communication lines.A PI controller compensates for the generated voltage offset to achieve bus voltage restoration and precise power allocation.Then,a system characteristic equation is built to analyze system stability and provide theoretical support for the proposed strategy.Finally,a DC microgrid model containing multiple distributed energy storage units is built by using Matlab/Simulink software and RT-LAB real-time simulation platform to verify the effectiveness of the proposed SOC balancing control strategy under different operating conditions. Our main conclusions are:① Compared to the exponential droop control,our strategy introduces an arctangent function to adaptively adjust the P-U droop coefficient based on SOC changes.Thus,it ensures the droop coefficient operates within allowable limits and guarantees system stability.Moreover,it improves the SOC balancing speed of DESUs and achieves fast SOC balancing.② By considering the influence of droop coefficients and line resistance,a single compensation term is designed to solve power distribution deviation caused by mismatched line resistances in DESUs,and maintain bus voltage stability.Compared to traditional strategies,our solution only requires one compensation loop to achieve both bus voltage restoration and power distribution deviation objectives,thereby reducing overall system design complexity.③ Our strategy is not affected by the fluctuations in photovoltaic output power,load variations or DESU switching operations,demonstrating its effectiveness and feasibility.关键词
直流微电网/分布式储能/功率分配/荷电状态/母线电压恢复Key words
DC microgrid/distributed secondary control/SOC balancing control/voltage compensation/power distribution分类
信息技术与安全科学引用本文复制引用
贾勇,刘文科,薛灵冰,李柱,杨超,蒋东荣..分布式多储能的孤岛直流微电网SOC均衡控制策略[J].重庆理工大学学报,2024,38(23):173-181,9.基金项目
重庆市教委科学技术研究项目(KJQN202101118) （KJQN202101118）
重庆理工大学研究生教育高质量发展行动计划项目(gzlcx20242037) （gzlcx20242037）
重庆市自然科学基金面上项目(cstc2020jcyj-msxmX0349) （cstc2020jcyj-msxmX0349）
