Sliding Mode Control of Grid-connected Inverters Using Inverter Output Current

In this paper, the switching command is produced by a sliding mode controller so that inverter output current follows the load current. To this end, an appropriate sliding surface for inverter output current is first defined, whereby control law is derived. In grid-connected mode of operation in microgrids, it is desirable that the microgrid meets its local load and does not receive power from the main grid as far as possible. Moreover, the voltage and frequency of the point of common coupling (PCC) are determined by the main grid having high inertia. Hence, in this paper the control strategy is focused on the inverter output current. Furthermore, the performance of the proposed sliding mode controller is compared with that of a PI controller. Also, hyperbolic tangent function is used instead of sign function in sliding mode control approach to cope with the chattering phenomenon. Finally, the results obtained via simulations performed in MATLAB/SIMULINK environment show the superior performance of proposed controller for a variety of load types such as linear and nonlinear load.