Abstract:The common use of open communication networks in interconnected power systems has turned the constant time delay of the original dedicated channel into the time-varying time delay. The time-varying time delay deteriorates the dynamic performance of load frequency control（LFC）and lead to system frequency instability. Therefore，the sliding mode LFC method for time-varying delayed multi-regions interconnected power systems is proposed and stability analysis is conducted based on the Lyapunov functionals. Firstly，the Caputo-type fractional-order Lyapunov functional is introduced into the stability analysis，and the conservativeness of the stability analysis is reduced by adjusting the upper limit of the function integral；then，the stability conditions of the time varying time delay power system described by the linear matrix inequality are obtained by combining Lyapunov theory and the integral inequality；finally，simulations are conducted to verify the impact of the proposed control strategy on the dynamic performance of the LFC and the robustness to load disturbances and wind power fluctuations.