Sampled-data automatic load frequency control of a single area power system with multi-source power generation

In this article, discrete-mode automatic load frequency control (ALFC) of a more realistic single area power system with multi-source power generation is studied. The system transfer function model comprises hydro, thermal and gas generations with speed governor models and system load for studying the dynamic performance for small load disturbances. A proportional plus integral (PI) load frequency control scheme is applied only to thermal and gas power generations, and hydro is allowed to operate at its scheduled generation level with only speed governor control. Genetic algorithm (GA) is used to obtain the optimal gains of the conventional discrete data proportional-integral controller. Integral squared error (ISE) and integral time absolute error (ITAE) performance indices are used to obtain optimal discrete ALFC parameters. The effects on transient performance of the system are investigated for common and individual ALFC controller gains of thermal and gas power generations. The effect of sampling period of the controller signal on the performance of the continuous system is also investigated. Finally, transient responses are shown for different scheduled loading conditions.