Sampled-data-based load frequency control for power systems considering time delays

This paper proposes a time-delay/sampling-period-dependent load frequency control (LFC) scheme for power systems. First, considering the influence of transmission delay and sampling period, the LFC model of a closed-loop power system is established. Then, a less conservative stability criterion is derived using a looped-function-based Lyapunov-like functional and linear matrix inequalities (LMIs) technique. Based on the stability criterion obtained, the update period, transmission delay, and exponential decay rate are the conditions to guide the controller design. The non-convex problem existing in the controller solution process is transformed into the nonlinear minimization problem based on LMIs, and an improved cone-complementary linearisation (CCL) iterative algorithm is used to obtain the state feedback controller with exponential decay rate index under a given transmission delay and sampling period. Finally, the effectiveness of the proposed method is verified by single-area and three-area power systems.