AGC of interconnected multi-source power system with considering GDB and GRC nonlinearity effects

In this paper, automatic generation control (AGC) problem of an interconnected two-area multi-source power system is investigated. Each control area includes generations from reheat thermal, gas, and hydro units. Appropriate dynamic models are used for simulation of physical constraints of governor dead band (GDB) effect in the reheat thermal and generation rate constraint (GRC) in the reheat thermal and hydro generating units. This paper demonstrates that evaluating the dynamic performance of AGC without regarding these issues does not show precise and realistic results. A simple integral (I) controller is considered as secondary load frequency controller (LFC) loop. The LFC design is formulated as an optimization problem in which integral of time multiplied squared error (ITSE) performance index is minimized by an improved particle swarm optimization (IPSO) algorithm to adjust I controller. The LFC performance is evaluated under step, sinusoidal and random load perturbation patterns. To show the robustness of the proposed approach, sensitivity analyses are performed under various uncertainty scenarios. All simulations are performed in MATLAB/SIMULINK environment. The results are compared with the case of without considering the GDB and GRC non-linearity effects. The results demonstrate that with considering the GRC and GDB, the oscillations are not damped effectively and even they are increasing under uncertainty conditions.