This paper deals with load frequency control of interconnected power system before and after the deregulation. In this particular work two area concepts is considered. The primary purpose of the LFC (loud frequency control) is to balance the total system generation against system load and losses so that the desired frequency. Any mismatch between generation and demand causes the system frequency to deviate from schedule value. Thus frequency deviation may lead to system collapse. Further, in a

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... estructured power system, the engineering aspects of planning and operation have to be reformulated although essential ideas remain the same.