An LMI approach to the design of robust delay-dependent overlapping load frequency control of uncertain power systems

• We consider the power tie-line as the overlapping part in multi-area power systems.
• We consider model uncertainties and time delays in load frequency control design.
• We propose a new method for load frequency control based on overlapping decomposition.
• The proposed approach provides better performance compared with existing results.

This paper considers the design of a fixed structure robust H∞H∞ Load Frequency Controller (LFC) for an uncertain state-delayed power system. The time-delay, which is due to information transfer over communication links, is assumed to be unknown but upper bounded by a known constant. The uncertainties are parametric and assumed to be norm bounded. The design approach is based on the principle of overlapping decomposition where the tie-line power is modelled as the overlapping variable between the interconnected areas comprising the power system. The design is formulated as a Linear Matrix Inequality (LMI) problem, the solution of which returns a fixed structure delay-dependent robust LFC. The validity of the proposed design approach is demonstrated through simulation studies carried out on an uncertain, state-delayed 2-area interconnected power system. The simulation results clearly illustrate better performance of the proposed robust H∞H∞ LFC, compared with existing designs.