LVRT capability improvement of a grid-connected PV park by robust sliding mode control

This paper presents a robust sliding mode based control method of a grid connected large scale photovoltaic (PV) system to enhance low voltage ride through performance. Recent grid codes dictate that PV plants need to stay connected with the power grid during the network faults because of their increased power penetration level. This requires the system to have large disturbance rejection capability to withstand against network disturbance and provide dynamic grid support. For the sake of faster current control in the inner loop of the inverter, a sliding mode control scheme is proposed in order to improve the fault ride through capability of a PV plant. A novel control coordination is also presented to reduce the power mismatch during the fault condition in order to limit the fault currents, which is one of the salient features of this study. The performance of the overall system using proposed controller is analyzed using laboratory standard power system simulation software PSCAD/EMTDC and results are compared with conventional controller.