Implementation of Virtual Impedance Strategy Applied for Grid-tied PV System.
Renewable Generation Systems, Photovoltaic Systems, Power Flow Control, Virtual Impedance.
The advances in power electronics and environment restrictions have driven the insertion of renewable energy based systems on power grid. Generally, these generation systems use the solar and/or wind energy as primary source and, mostly, they are connected to the power grid through power electronics converters. The integration of these systems into the grid brings with it some problems, due to its stochastic generation, as instability of the electric power system in which the renewable generation system is connected. Therefore, it is important to use an efficient control system to ensure the proper functioning of the system. A control strategy that has been increasingly used with the increase of the integration of renewable generation systems is the virtual impedance. With the use of virtual impedance in the control strategy there is the possibility to modify the dynamic behavior of converters, changing its output impedance, without presenting additional
losses to the system. There are several applications with the implementation of
virtual impedance, such as: power flow control, harmonic and unbalance Compensation, active stabilization, among others. The proposal of this work is the implementation of a control structure in which the output currents and voltages of the inverter are controlled and, with the use of virtual impedance, permits to modify the output power flow of the converter.