Abstract: Load frequency Control is very important in the power system operation and control for supplying sufficient and reliable electrical power with good quality. The load demand should match the power generation. If there is any imbalance leads to a load frequency problems. In general, as the speed of the machine depends on the frequency, any deviation in the frequency may lead to mal-operation of the system. So load frequency control is the key problem in the power system. For specified power rating of the machine the voltage should maintain constant otherwise the system insulation may get damage. The controllers are set for a particular operation condition and they take care of small changes in load demand without frequency and voltage exceeding the prescribed limits. With the passage of time, as the change in load demand becomes large, the controllers must be reset either manually or automatically. In modern power system multi area inter connected systems are used for more reliability and economic purpose. In this paper using four areas for inter connected systems the frequency problems can be effectively decreased by using fuzzy logic controller with either of the 3, 5 or 7 membership functions. Here this fuzzy logic controller action also compared with automatic generation control and PID controllers also. By using fuzzy logic controller the frequency error, settling time, peak overshoot, under overshoots are effectively reduced.

Keywords: Frequency error, multi area inter connection, Automatic Generation Control (AGC), Fuzzy logic controller, PID.