Fully distributed energy management strategy for DC bus charging stations with three charging modes

Area of Science:

• Electrical Engineering
• Power Systems
• Control Theory

Background:

• Electric vehicles (EVs) reduce CO2 emissions, but islanded multi-bus DC charging stations face challenges in accurate current sharing.
• Existing methods require global network information and high bandwidth, hindering large-scale deployment.
• EVs exhibit diverse charging modes (constant current, constant power, constant voltage), complicating control.

Purpose of the Study:

• To propose a fully distributed dynamic event-triggered consensus control for accurate current sharing in islanded multi-bus DC charging stations.
• To overcome limitations of global structure information and high communication bandwidth requirements.
• To address challenges posed by multiple EV charging modes.

Main Methods:

• Developed a system model for multi-bus DC charging stations with three EV charging modes.
• Designed a primary virtual impedance controller to mitigate low-frequency oscillations from constant power loads.
• Formulated a state-space function considering power coupling among DC buses.
• Proposed a fully distributed dynamic event-triggered consensus control using coupling weights to determine control gains without global network topology.

Main Results:

• Achieved accurate current sharing among distributed generators (DGs) in islanded multi-bus DC charging stations.
• Successfully eliminated low-frequency oscillations caused by constant power charging.
• Demonstrated the absence of Zeno behavior in the proposed control strategy.
• Validated the control approach through simulation and experimental results.

Conclusions:

• The proposed fully distributed dynamic event-triggered consensus control effectively enables accurate current sharing in islanded DC charging stations.
• The control strategy is robust to different EV charging modes and does not require global network information.
• This approach facilitates the large-scale development of efficient and reliable EV charging infrastructure.