Mitigating Balanced and Unbalanced Voltage Sag Via Shunt-Connected Voltage Source Convertor (VSC) by using Double Vector Controller

摘要

This study presents a shunt-Connected Voltage Source Convertor (VSC) to mitigate balanced and unbalanced voltage sag and regulate the grid voltage at a fixed level by inserting required reactive power at the Point of Common Coupling (PCC). Moreover, an inner Vector Current-Controller (VCC) and outer voltage controller (VVC) are applied together to calculates the current references for the VCC. Furthermore, an inductor/ capacitor/inductor (LCL) filter is replaced with the simple L-filter in between the VSC and the network and it is constructed to reduce the voltage sag. Likewise, to make up for the unbalanced dips, the positive and negative sequence components related to the grid voltage should be managed distinctly. The positive and negative sequence components related to the grid voltage should be managed distinctly. This is achieved through the application of two independent controllers for the two sequences with an identical cascade structure which has been explicated above. Simulation results designate proper functioning of the control system which has been proposed.