I. Introduction
With the present global scenario of electricity such as enormous increase in power demand, environmental policy and the restructuring & de-regulation of electric supply system, power generation technologies are gaining importance on its own way to explore many advantages like less environmental pollution, high efficiency, cleanliness and safe operation, dependable, and ecologically friendliness [1] –[8]. Energy resources are being explored that are capable of making a substantial contribution to fulfilling the world’s future energy requirements [9]. Electric power utility precedes many important functions in energy management systems, which continuously monitor systems and initiates the required control actions in critical situations. Generation and security of supply have to be given proper importance while dealing with power system operation and planning [10] utilizing critical decision support tools required for operating electrical power system securely and economically [11]. Power systems as seen globally, are made up of two or more generating and distribution power systems. These large power systems consist of interconnected power subsystems covering wide geographical control areas (CA) [12]. Each of these subsystems has different generating capabilities with variable load demands. The control of power flow between these areas is through the tie-lines. Since these several subsystems and the control areas are linked together, the load disturbance and load demand change in an area can alter the output frequencies of other interconnected areas including power flow on the tie-line [13]. The real-life behavior of power systems shows that there are always load dynamic issues having to do with load changes especially dealing with the rate of change [14]. Extensive research has been conducted on LFCs control algorithms and methodologies, to manage these load perturbations and keep the steady-state errors to zero amongst other constraints, which has resulted in the development of several techniques for the LFC problem [15].