Sliding mode based feedback linearizing controller for a PV system to improve the performance under grid frequency variation

This paper proposes an effective control strategy for a single-stage, three-phase PV system, supplying local load and integrated with the grid. Maximum power tracking is achieved with interleaved inner current control loop and outer voltage control loop. The output of PV generator is processed by the voltage source converter, a well established dc/ac converter. But these converter systems are highly non linear and coupled. Since the conventional PI controller will not give the satisfactory performance for the changing operating conditions and uncertain load changes, the feedback linearization scheme has been formulated. Sliding mode control technique has been incorporated in the feedback linearized control to address the issues of uncertainty and to add robustness to the control algorithm. The developed control algorithm is tested for the maximum power extraction at different insolations, controlling the dc/ac converter as an ancillary service to supply reactive power, load uncertainties and finally for variable grid frequency within a small band.