Virtual series impedance emulation control for remote PV or wind farms

This paper proposes a virtual series impedance emulation control strategy for current controlled remote PV or wind farms, in order to enhance the power transfer capability of the transmission line. This approach can be regarded as integrating the functions of the FACTS devices, such as series capacitors, into the grid-side converters of PV or wind farms, by utilizing the reactive power capability of the converters. First, the virtual series impedance emulation control strategy for PV or wind farms in both the operation mode with P and Q control and the operation mode with P and V control is described. Then the capability of virtual impedance emulation is analyzed, considering the converter limitations and plant-level limitations. Comparison with physical series capacitors is carried out to investigate the impact of the proposed method on the grid-side converter design. The effectiveness of the proposed methods is verified by both simulation and experiments.