Voltage sags/swells subsequent to islanding transition of PV-battery microgrids

This paper investigates the transient voltage sags/swells subsequent to islanding of a PV-Battery microgrid. For an unplanned islanding and micro-grid formation, during islanding detection time, the microgrid is disconnected from main grid while the control mode of the BESS stays the same as before. Consequently the microgrid will undergo transient voltage sag or swell caused by the mismatch of the source output and the load power and the switch transients. The microgrid studied includes a diesel synchronous generator, an inverter-based PV system and an inverter-based battery storage system. The PV system is operated in MPPT mode. And the battery system is operated by a PQ controller in grid-connected mode and by a V/f controller in islanded mode. Matlab/Simulink is adopted to model the microgrid under study. The voltage transients in several scenarios of the microgrid are simulated.