Modeling and Analyzing of Inverters for Controlling Voltage and Frequency in an Islanded Microgrid

Abstract

Recently, the growth of inverter-based generations (IBGs) like solar photovoltaic (PV) and wind turbine generators in the form of microgrids (MGs) has been increasing. However, control of voltage and frequency becomes a challenging task for MGs especially when they operate in an islanded mode, due to the inherent low-inertia feature of IBGs compared to a grid-tied mode where there is a grid support. This thesis deals with modeling and analyzing of inverters capable of controlling voltage and frequency through external conventional droop control for the islanded operation of MG. In this thesis, a state space model is developed for a voltage source inverter with droop control. Moreover, non-linear models for the inverters in single and parallel cases with droop control are developed and the results are verified in different load scenarios. The results show a good performance of the projected control, both in the isolated operation of an inverter supplying a load, and in the parallel operation of isolated inverters, where there is power sharing to properly feed the load. MATLAB/Simulink environment is used for the work.