Under Voltage-Frequency Load Shedding in an Islanded Inverter-based Microgrid using Power Factor-based P-V curves

Considerable penetration of distributed generation (DG) in power systems has opened an option of operating DGs in islanded mode for economic and technical reasons. However, maintaining voltage and frequency in the allowable range, as two main symptoms for proper performance of a power network, is a crucial challenge in islanded inverter-based microgrids (IBMG). In the event of severe contingencies, load shedding (LS) can be the last solution which recovers the voltage and frequency of the system. This study introduces an under voltage-frequency LS (UVFLS) scheme to achieve proper load shedding amounts (LSAs). In this paper, state-space model of IBMG and a fast time-step simulation approach, based on the complete state-space model of IBMG has been equipped, in order to obtain responses of the system. A precise method for calculating P-V curves according to loads PF is presented to derive the optimum LSA. Simulation studies are carried out on a test IBMG in presence using MATLAB software to validate the proper performance of proposed voltage and frequency recovery method.