Since high power energy transmission is required for a grid-level energy storage system,a high-power energy storage system based on modular multilevel converter(MMC)is very promising at present.However,in order to pro...Since high power energy transmission is required for a grid-level energy storage system,a high-power energy storage system based on modular multilevel converter(MMC)is very promising at present.However,in order to produce desired high power,an MMC-based energy storage system needs to be constructed by cascading a large number of energy storage units,which will make it difficult to balance state of charge(SOC)of these units.To solve SOC unbalancing of these units,special modeling and control methods are employed and an SOC balancing controller is designed.First,a high-power energy storage system is modeled as a multi-agent model.Then,an event-trigger control method is used to control information transmission and operation period of the energy storage agent,which further reduces the amount of communication and computation.Moreover,observers are designed to estimate battery current,which can reduce in half the amount of status information that needs to be collected.Finally,the simulation platform of the MMC-based storage system is established with MATLAB,the proposed SOC balancing control method is simulated and its validity is verified.展开更多
A modular multilevel converter(MMC)integrated with split battery cells(BIMMCs)is proposed for the battery management system(BMS)and motor drive system.In order to reduce the switching losses,the state of charge(SOC)ba...A modular multilevel converter(MMC)integrated with split battery cells(BIMMCs)is proposed for the battery management system(BMS)and motor drive system.In order to reduce the switching losses,the state of charge(SOC)balancing strategy with a reduced switching-frequency(RSF)is proposed in this paper.The proposed RSF algorithm not only reduces the switching losses,but also features good balancing performance both in the unbalanced and balanced initial states.The results are verified by extensive simulations in MATLAB/Simulink surroundings.展开更多
The unbalanced state of charge(SOC)of distributed energy storage systems(DESSs)in autonomous DC microgrid causes energy storage units(ESUs)to terminate operation due to overcharge or overdischarge,which severely affec...The unbalanced state of charge(SOC)of distributed energy storage systems(DESSs)in autonomous DC microgrid causes energy storage units(ESUs)to terminate operation due to overcharge or overdischarge,which severely affects the power quality.In this paper,a fuzzy droop control for SOC balance and stability analysis of DC microgrid with DESSs is proposed to achieve SOC balance in ESUs while maintaining a stable DC bus voltage.First,the charge and discharge modes of ESUs are determined based on the power supply requirements of the DC microgrid.One-dimensional fuzzy logic is then applied to establish the relationship between SOC and the droop coefficient R,in the aforementioned two modes.In addition,when integrated with voltage-current double closed-loop control,SOC balance in different ESUs is realized.To improve the balance speed and precision,an exponential acceleration factor is added to the input variable of the fuzzy controller.Finally,based on the average model of converter,the system-level stability of microgrid is analyzed.MATLAB/Simulink simulation results verify the effectiveness and rationality of the proposed method.展开更多
基金supported by the National Natural Science Foundation of China(No.51907018)by the Fundamental Research Funds for the Central University(No.N2004009).
文摘Since high power energy transmission is required for a grid-level energy storage system,a high-power energy storage system based on modular multilevel converter(MMC)is very promising at present.However,in order to produce desired high power,an MMC-based energy storage system needs to be constructed by cascading a large number of energy storage units,which will make it difficult to balance state of charge(SOC)of these units.To solve SOC unbalancing of these units,special modeling and control methods are employed and an SOC balancing controller is designed.First,a high-power energy storage system is modeled as a multi-agent model.Then,an event-trigger control method is used to control information transmission and operation period of the energy storage agent,which further reduces the amount of communication and computation.Moreover,observers are designed to estimate battery current,which can reduce in half the amount of status information that needs to be collected.Finally,the simulation platform of the MMC-based storage system is established with MATLAB,the proposed SOC balancing control method is simulated and its validity is verified.
文摘A modular multilevel converter(MMC)integrated with split battery cells(BIMMCs)is proposed for the battery management system(BMS)and motor drive system.In order to reduce the switching losses,the state of charge(SOC)balancing strategy with a reduced switching-frequency(RSF)is proposed in this paper.The proposed RSF algorithm not only reduces the switching losses,but also features good balancing performance both in the unbalanced and balanced initial states.The results are verified by extensive simulations in MATLAB/Simulink surroundings.
基金supported by the National Natural Science Foundation of China(No.U22B20116).
文摘The unbalanced state of charge(SOC)of distributed energy storage systems(DESSs)in autonomous DC microgrid causes energy storage units(ESUs)to terminate operation due to overcharge or overdischarge,which severely affects the power quality.In this paper,a fuzzy droop control for SOC balance and stability analysis of DC microgrid with DESSs is proposed to achieve SOC balance in ESUs while maintaining a stable DC bus voltage.First,the charge and discharge modes of ESUs are determined based on the power supply requirements of the DC microgrid.One-dimensional fuzzy logic is then applied to establish the relationship between SOC and the droop coefficient R,in the aforementioned two modes.In addition,when integrated with voltage-current double closed-loop control,SOC balance in different ESUs is realized.To improve the balance speed and precision,an exponential acceleration factor is added to the input variable of the fuzzy controller.Finally,based on the average model of converter,the system-level stability of microgrid is analyzed.MATLAB/Simulink simulation results verify the effectiveness and rationality of the proposed method.
