Multiple Modes Control of Household DC Microgrid with Integration of Various Renewable Energy Sources

Increase of DC-compatible loads, popularization of renewable distributed generations (DGs) and development of power electronic converters have boosted the applications of DC microgrid in household level. Proper control algorithms for autonomous operation of DC microgrid which coordinates the operation of energy storages, sources and loads become the key challenge. Comparing with centralized energy management system, distributed control eliminates communication link, thus system response speed and reliability could be enhanced. DC-bus signaling (DBS) in which the bus voltage is regarded as global indicator for system power balance is an effective solution for power sharing. Bus voltage band is divided into few sub-regions around the nominal value. Various elements are prioritized based on system control objectives and scheduled to operate with different mode in respective sub-region. Bus voltage variation induced by power supply/demand difference activates operation mode change of system elements autonomously. A lab-scale DC microgrid with integration of modular solar Photovoltaic (PV) system, battery energy storage (BES) and DC loads was developed to verify the feasibility and effectiveness of proposed control algorithm.