Load frequency control (LFC) is used as part of automatic generation control (AGC) in power systems. LFC with the automatic voltage regulator (AVR) plays an important role in maintaining the frequency and constant voltage. In this paper, a method for load frequency control in reconstructed electrical systems using high voltage direct current (HVDC) line is presented. An accurate and complete model based on the control circuit and equations with HVDC controller design is considered and its parameters are optimized using the harmony search algorithm (HAS). To test the method, the power system is simulated with three-area. The simulation results show the proper performance of the power system against sudden load changes and disturbances caused by other areas. پرونده مقاله