Load-frequency control (LFC) in interconnected power systems is undergoing fundamental changes due to rapidly growing amount of wind turbines, and emerging of new types of power generation/consumption technologies. The infrastructure of modern LFC systems should be able to handle complex multiobjective regulation optimization problems characterized by a high degree of diversification in policies, and widely distribution in demand and supply sources to ensure that the LFC systems are capable to maintain generation-load balance, following serious disturbances. Wind power fluctuations impose additional power imbalance to the power system and cause frequency deviation from the nominal value. This paper addresses a new decentralized fuzzy logic-based LFC schemes for simultaneous minimization of system frequency deviation and tie-line power changes, which is required for successful operation of interconnected power systems in the presence of high-penetration wind power. In order to obtain an optimal performance, the particle swarm optimization technique is used to determine membership functions parameters. The physical and engineering aspects have been fully considered, and to demonstrate effectiveness of the proposed control scheme, a time domain simulation is performed on the standard 39-bus test system. The results are compared with conventional LFC design for serious load disturbance and various rates of wind power penetrations.