Further Improvement on Stability Results for Delayed Load Frequency Control System via Novel LKFs and Proportional-Integral Control Strategy

In this work, novel stability results for load frequency control (LFC) system considering time-varying delays, nonlinearly perturbed load, and disturbance of parameters are proposed by using proportional-integral strategy. Considering the exogenous disturbance, an improved criterion in form linear matrix inequalities (LMIs) is derived simple Lyapunov–Krasovskii functionals (LKFs). The delay-dependent quadratic term, cross terms variables, multiplied 1st, 2nd, 3rd degrees scalar functions included new LKF. Taking single-area two-area LFC installed with (PI) controller as example, our surpass previous maximum allowable size time delay. Meanwhile, relationship between delay varying rate, degree, gains PI controller, margin researched separately. can provide guidance to tune achieving margin, which withstand without losing stability. At last, simulation verify effectiveness superiority criterion.