SEAMLESS MODE CHANGE BETWEEN GRID-CONNECTED MODE AND ISLANDED MODE FOR PV SYSTEMS

• Main Authors: REN, Beibei, WANG, Yeqin
• Format: Patent
• Language: English
• Published: 15.08.2024
• Subjects: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC,OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWERSUPPLY SYSTEMS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTINGELECTRIC POWER; CONTROL OR REGULATION THEREOF; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUTPOWER; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; GENERATION; SYSTEMS FOR STORING ELECTRIC ENERGY

A unified control scheme to achieve seamless mode change between grid-connected mode and islanded mode for photovoltaic (PV) systems includes two decoupled control units: a DC-DC converter control unit and a DC-AC converter control unit. The DC-bus voltage is controlled through the DC-DC converter control unit, which supplies a "stiff DC source" to the DC-AC converter. The seamless mode change is implemented in the DC-AC converter control module via three digital switches between power flow control for grid-connected mode (or MPPT mode), and droop control for islanded mode (or droop mode), while preserving the continuity of control signals in all control units with the configurations of digital switches.