This article concerns the design of linear feedback controllers for the load frequency control loop of a single area power plant. The system is affected by unknown piecewise constant power load disturbances. The control objective is formulated as a robust regulation control problem relying on an augmented state-space description by an integrator applied on the frequency deviation error. The primary controller achieves pole clustering in a prespecified LMI region, while in the sequel it is further enhanced with disturbance attenuation properties. In any case, the power load disturbances are rejected due to the integrator, while the transient behavior is determined by tuning the control parameters through a trade-off between performance criteria and actuation authority. Extensive simulation results demonstrate the complexity aspects of the design procedure and highlight the efficiency of the proposed control schemes.