A study on AGC scheme based on real time frequency characteristics

Automatic generation control (AGC) has been one of the important issues in the operation of local area and interconnected power systems. AGC provides power demand signals for AGC power generators to control frequency. In AGC, some variables of power system such as frequency and power generation are measured to calculate the area control error (ACE). The ACE value is an important factor of AGC performance. Generally, ACE value is determined by a constant frequency bias factor of power system or 1% of load method. The ACE value based on the constant frequency bias factor or 1% of load method, however, may not represent the real time status of power system correctly. The incorrect ACE value is a cause of over regulation of power system. This paper presents the method to decide actual frequency bias factor on real time frequency characteristics. In this paper, the actual frequency bias factor is determined by the measured variables such as generator power output change and frequency deviation due to disturbance of power system. The actual frequency bias factor calculated is used to determine the ACE of power system. The AGC divides the calculated ACE among AGC power generators periodically. The period is determined by the time of recovered frequency. This paper also presents the simulation results for the power system model about the proposed AGC scheme. The simulation results show that the performance of AGC is improved when the proposed AGC scheme is applied to AGC.