On robust control analysis and design for load frequency regulation

This paper addresses the analysis and design issues in load frequency control (LFC) for a power system entity that participates in interconnection. The basic physical control mechanisms are the same whether the entity is a vertically integrated utility, an independent system operator or a virtual control area in a fully de-regulated market. Goals of this paper are twofold: to examine a rationale for known heuristic design guidelines; and to suggest an orderly methodology for control synthesis. Motivated by the large uncertainty in dynamic models of power system components and their interconnections, this paper proposes a physically motivated passivity objective as a means to achieve effective closed-loop control. Quantitative feedback theory provides convenient graphical tools for suggested design and analysis methods. A simulation model of a two-system interconnection is used as an illustration.