Dynamic modeling and performance analysis of an autonomous and non-autonomous microgrid

Abstract

A microgrid system with a power system grid connection is advantageous because it can depend on the power grid when additional power is needed. Alternatively, it can also feed the grid with its excess generation. This project looks into the dynamic behavior of a microgrid when it switches from non-autonomous to autonomous mode. Non-linear dynamic model of non-autonomous as well as autonomous systems for a PV-wind-microalternator-STATCOM integrated microgrid system has been developed. Non-linear state equations for the various components of microgrid are modeled in terms of a 28th order dynamic model. The performance of the system is also evaluated by solving the differential equations through MATLAB ode programs. The power generated by three different generating sources are fed to the point of common coupling (PCC) so that the excess generation can be supplied to the main grid. The effect of temporary and permanent fault in the system network has been investigated. A STATCOM controller connected to the microgrid gives voltage support to the system during contingencies. Simulation results suggest that the proposed model can effectively operate in non-autonomous mode until severe disturbance is encountered in the main grid. It also shows that it is capable of switching to the autonomous mode once the disturbance is found to be severe or if it persists for a longer time. The results also shows that the fluctuation in the output waveform is minimum during the period of transition.