Frequency stabilization of isolated and grid connected hybrid power system models

This paper investigates the load frequency control (LFC) of two different configurations of power system model. The first one is worked as an isolated hybrid power system (HPS) (IHPS) while the second one is a grid tied HPS (GHPS). In IHPS, the power generating units are diesel engine generator (DEG), wind turbine generator (WTG) and solar thermal power generation (STPG). It is considered in such a way that the generation persists throughout the day with uninterrupted power supply. The energy storage device used in this work is superconducting magnetic energy storage (SMES). The three scenarios considered in isolated mode are (a) HPS with one DEG, one WTG and one STPG, (b) HPS with one DEG and one STPG and (c) HPS with one DEG and one WTG. As concerned to GHPS, a combination of WTG and steam thermal power plant is considered. A conventional proportional-integral-derivative (PID) controller has been used as supplementary control mechanism. The PID controller gains and the tunable parameters of the SMES are tuned by the use of quasi-oppositional harmony search (QOHS) algorithm. Initially, integral of time absolute error based objective function is minimized and, subsequently, three performance indices such as integral of absolute error, integral of square error and integral of time square error are calculated to test the designed efficiency of the proposed QOHS based PID controller. The transient responses of systems pertaining to step and random changes in the load demand are analyzed. The simulated results obtained by the QOHS algorithm reveals that it may be imposed to boost LFC performance of the power system.