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Top1. Introduction
Nowadays, in the global open market, load demand is a major hike due to the industrial enlargement and equipment growth in domestic applications in the world. Consequently, power demand the eminence of the power supply will be affected in terms of the frequency changes and voltage deviations for all consumers. In recent years, achieving the consistency in frequency and tie-line power flow of an interconnected multi area power system attracts the focus of several researchers. Since, power quality indicates the consistency of the frequency, voltage and level of reliability. Thus, the power system engineers are concerned with providing economical, adequate and good quality power to the consumers (Chatterjee, 2011; Kumar & Sharma, 2012). This requires a balancing of the total system generation against the system load and losses to maintain the frequency and tie-line power at the desired values to achieve the economical and reliable requirements. Initialization of large load provides the required power demand in power system. The large load demand is achieved by the initializations of steel mills, Arc furnace etc. The mismatch in electrical load and power supplied by the generator causes the frequency changes and tie-line power deviation in an interconnected power system. The aim of load frequency is to regulate the system frequency at the scheduled value and regulate the interchange tie-line power flow between control areas (Kumar & Sharma, 2012).
Due to the natural fluctuations in the load characteristics, the steady state operation is impossible. However, there is possibility to keep the system with small tolerance levels. The change in real power affects the system frequency, whereas the voltage magnitude is not affected. Similarly, the change in the reactive power affects the bus voltage without altering the system frequency.
Typically, the Automatic Generation Control (AGC) problem can be subdivided into the primary (fast) and secondary (slow) modes (Kundur, 1994). Based on the primary and secondary control loop design, the system overall performance is varied. The primary controller is incorporated using the proper selection of governor droop or the governor speed regulation parameter in HZ/p.u.MW. The secondary controllers are used to select the classical controller. The secondary controller can also be called as supplementary controller. In practice, several classical controllers are available, such as the I, PI and ID controller. Time domain specification analysis has been carried out among these controllers and the performance are compared in order to select the best controller action (Anand & Jeyakumar, 2009; Nandha & Mishra, 2010; Jagatheesan & Anand, 2012). The PID controller gain values in AGC of multi-area hydro-thermal power system is tuned by considering ant colony optimization technique using integral time absolute error cost function (Jagatheesan et al., 2015). The fuzzy PI controller gain values in the AGC of multi-area interconnected power system was tuned by using novel hybrid PSO-PS technique and proposed technique based controller performance is compared with ZN tuned PI, VSS based ZN tuned PI controller, GA tuned PI, VSS based GA tuned PI controller performance in the same investigated power system (Sahu et al., 2015). Bat inspired algorithm based dual mode gain scheduling PI controller has been equipped in LFC of interconnected power system in (Sathya & Ansari, 2015).