In this paper, a multi-area interconnected power system load frequency control(LFC) model with a wind turbine and energy storage system(ESS) is established. Meanwhile, the system parameter uncertainties and the time delay of control channel in the ESS and traditional generator are considered. In order to improve the robustness of the power system and reduce the capacity of the ESS, a sliding model load frequency controller is designed for the LFC model with the wind turbine and ESS, and a coordination control strategy for the sliding model load frequency controller and ESS is proposed. The simulation result verifies that the proposed coordination control strategy can reduce the system frequency deviation and area control error effectively under the increase of new energy penetration and system load fluctuation, and decrease the capacity of the ESS, thus improve the economic performance of the power system.