Nonlinear Control of Voltage Source Inverters in Microgrids

Microgrids represent a new and flexible form of electrical networks. This form is based on the use of Distributed Generators which are connected to a microgrid through Voltage Source Inverters (VSI). In this paper, we propose a nonlinear controller that allows the regulation of the output voltage and frequency of a VSI. The system consists of a VSI and an LC filter associated to a coupling inductor. The main objective is to enforce the system output voltage to track a given reference. After the system modeling, the controller is designed using the backstepping technique. Once the control law is elaborated, several simulations are carried out to evaluate the performance of the proposed controller. The simulation results and formal analysis show that the output voltage tracks perfectly the reference voltage with a global asymptotic stability. It is worth mentioning that the designed controller can operate in the both microgrid modes: grid connected mode and islanded mode. 1 Keywords— Microgrid, distributed Generation, backstepping, VSI, LC filter, coupling inductor, modeling, stability, tracking.