Davar Mirabbasi - Department of Engineering, Ardabil Branch, Islamic Azad University, Ardabail, Iran
Mohsen Parvin - Department of Engineering, Ardabil Branch, Islamic Azad University, Ardabail, Iran
Hoseyn Javid - Department of Engineering, Ardabil Branch, Islamic Azad University, Ardabail, Iran

The main contribution of Load Frequency Control (LFC) is preserving frequency constantagainst the varying active power loads. System has several generating units in which thenotion of fault/load tolerance has to be enhanced. For this purpose tie-lines are made betweenthese interconnected units. In this paper, a fuzzy controller has been suggested for LFC ofmulti unequal area hydro-thermal interconnected power system. Simulation has beenperformed on a test system with four areas. First and second areas have thermal reheat powerplant and third and fourth areas consists of hydro power plant with electric governor.Simulation has been carried out by Matlab / Simulink software and capability of the proposedtechnique confirmed by comparing its results with related values of PI and PID controllers.

Load frequency control, Fuzzy controller, Controller design, Area hydro-thermal, Tie-line