A new method is presented for designing load frequency self-tuning regulators for interconnected power systems having unknown deterministic load disturbances. A discrete-type optimal control law is obtained by defining a cost function with a term for presenting the constraints on the control effort and then by minimizing it with respect to the control variable. An attractive feature of the proposed control scheme is that the effect of the load disturbances is decoupled from the plant output and the large value of control is discouraged indirectly by penalizing the rate of change of control. Another feature is that it considers the time delay due to the identification and control computations and the transmission time of the system data over the telemeter links to the controlling plant. The control effects of the proposed regulator are examined using digital simulations of a two-area power system provided with reheat steam turbines.