Protection of Decentralized DC Microgrid System Based on Detection of DC-Bus Voltage Sensor Faults

This paper proposes a secondary control for a decentralized DC microgrid (DCMG) based on the DC-bus voltage (DCV) monitoring value not only to achieve power and voltage regulation but also to protect the system under the DCV sensor faults. To enhance the reliability of the DCMG system, a voltage observer is implemented for each power agent to monitor the voltage sensor abnormality. Based on the DCV monitoring value, the secondary voltage restoration scheme and power-sharing controller are presented to ensure the power balance and maintain the DCV to the nominal value. Moreover, to improve the DCMG system stability under voltage sensor faults, a voltage sensor fault identification method is deployed for each power agent by detecting the DCV sensor malfunction. As soon as the power agent recognizes its DCV sensor fault, its operation is switched from the voltage control mode with the secondary voltage restoration and power-sharing controller to the current control mode to prevent the DCMG system collapse. Several simulations have been conducted to demonstrate the feasibility of the proposed approach under various scenarios.