This paper presents the significances of a novel quasi-oppositional harmony search (HS) (QOHS) algorithm in the context of automatic generation control (AGC) of power system. The proposed QOHS algorithm is framed by utilizing the quasi-oppositional concept in the pre-available basic HS algorithm. Also, the proposed algorithm houses both the characters of two guesses i.e. opposite-point and its mirror point (quasi-opposite point) to converge rapidly toward the optimal solution(s). The proposed QOHS algorithm is, individually, applied to single-, three- and five-area interconnected test power systems (considering suitable cases) for its survival in AGC domain. The single- and three-area test systems are supplemented with the proportional-integral-derivative (PID) controller installed in each control area. In the second phase of investigation, the proposed QOHS based integral-double derivative (IDD) controller is also examined in AGC mechanism of five-area test power system. Initially, integral of square error based objective function is minimized and, further, two performance indices (such as integral of time absolute error and integral of time square error) are also calculated to test the AGC performance offered by the proposed QOHS based PID/IDD controller. To add some degree of non-linearities, appropriate generation rate constraint (GRC) is also considered for both three- and five-area test power systems. The simulated results, as obtained by the proposed QOHS algorithm, are compared to those offered by other optimization algorithms reported in the recent state-of-the-art literature. The extensive results, as presented in this paper, reveal that the proposed QOHS algorithm may be, effectively, imposed to boost the AGC performance of power system having various degrees of complexities (like model uncertainties) and non-linearities (like GRC). 
A novel quasi-oppositional harmony search algorithm for automatic generation control of power system