Large-signal model of DC micro-grid systems feeding a constant power load

Generally, the mathematical model of DC micro-grids (DCMGs) with bi-directional voltage source converter (VSC) is time-varying due to the switching action. The time-varying model is very complicated for controller design or stability analysis. As a result, this article presents how to derive the mathematical model using a combination between DQ method and the generalized state-space averaging method (GSSA) to achieve the time-invariant model. The time-invariant model is suitable for controller design or stability analysis via the basic control theory. The computer simulations with the SimPowerSystem™ on MATLAB program have been used for the model validation. The results show that the good accuracy of mathematical model in transient and steady-state responses can be obtained. Then, the resulting mathematical model can be used to design the controller or analyze the unstable point of the system in the future work.