Constrained load-frequency control

Load-frequency control (LFC) is one of the major problems when dealing with the design and/or operation of electric power systems. Moreover, due to practical and physical considerations, bounds are often imposed on the level of control signals as well as the maximum frequency deviation. Control strategies that satisfy systems constraints, and, at the same time, guarantee optimal systems performance, are often more difficult to achieve. In this article, a technique is developed for the solution of LFC problems with state and/or control constraints via the solution of constrained linear quadratic problem (LQP). After formulating the problem and deriving the necessary conditions of optimality, an iterative algorithm is proposed that leads to the optimal control strategy while satisfying systems constraints. In order to illustrate the effectiveness of this technique, one- and two-area constrained LFC problems are solved, and the results are demonstrated at the end of the paper.