A load frequency control design using the sliding mode control theory with a VSS observer

In recent years, power systems have steadily grown larger and more complicated. Meanwhile, there has been a push toward strong deregulation of the power industry, which has also progressed, causing increases in the PPS (Power Producers and Suppliers) generation ratio and power wheeling via the tie-lines connecting different power companies. These factors all contribute to the increase of uncertainties in the power system. The sliding mode control theory is one type of robust control theories, which can consider modeling uncertainties. Therefore, in this paper, the sliding mode control theory is applied to the load frequency control (LFC) in power systems, together with a VSS observer. Its robustness and control performances of the proposed method are examined by numerical simulations and comparisons with the conventional PI controller.