Load Frequency Control for Micro Hydro Power Plants by Sliding Mode and Model Order Reduction

Abstract

Original scientific paperMicro hydro is treated as a major renewable energy resource. Such a kind of plants blooms because they can evade some dilemmas like population displacement and environmental problems. But their performance on the frequency index of power systems may be deteriorated in the presence of sudden small load perturbations and parameter uncertainties. To improve the performance, the problem of load frequency control (LFC) raises up. Design of state-based controllers on the aspect of modern control is challenging because only a part of the system states are measurable. This paper addresses the scheme of sliding mode control by model order reduction for the LFC problem of micro hydro power plants. The kind of plants usually has two operating modes, i.e., isolated mode and grid-connected mode. Under each operating mode, mathematical model and model reduction are investigated at first. According to the reduced-order model, a sliding mode control law is subsequently derived. Since the control law is applied to the original system, a sufficient condition about the system stability is proven in light of small gain theory. Simulation results illustrate the feasibility, validity and robustness of the presented scheme. Key words: Load Frequency Control, Micro Hydro Power Plants, Model Order Reduction, Sliding Mode ControlUpravljanje frekvencijom i radnom snagom mikro hidroelektrana kliznim režimom rada i redukcijom reda modela sustava. Mikro hidroelektrane smatraju se jednim od glavnih obnovljivih izvora energije. Ovakve elektrane su poglavito zanimljive pošto izbjegavaju dileme vezane za iseljavanje ljudi i utjecaj na okoliš. Međutim, njihov učinak na indeks frekvencije energetskih sustava može biti negativan zbog naglih manjih promijena u opterećenju i nesigurnosti parametara. Kako bi se unaprijedila učinkovitost, javlja se problem regulacije frekvencije i radne snage. Projektiranje regulatora po varijablama stanja sustava izazovan je problem, jer je mjerljiv samo dio stanja sustava. Ovajčlanak analizira problem upravljanja kliznim režimom rada reducirajući red modela sustava kod regulacije frekvencije i radne snage mikro hidroelektrana. Ovakve elektrane mogu raditi u samostalnom režimu rada ili biti spojene na distribucijsku mrežu. Za oba ražima rada prvo se istražuju matematički modeli te potom njihova redukcija. S obzirom na model reduciranog reda izvodi se upravljački zakon kliznog režima rada. Pošto se zakon upravljanja primjenjuje na izvorni sustav, dokazan je dovoljan uvjet za stabilnost u vidu teorije malog pojačanja. Simulacijski rezutati pokazuju izvedivost, ispravnost i robustnost predloženog pristupa.Ključne riječi: upravljanje frekvencijom i radnom snagom, mikro hidroelektrane, redukcija reda modela sustava, upravljanje u kliznog režimu rada

Design of a Low-Cost Autonomous Controller, Management and Security System for Pico-Hydroelectric Power Plants

“…Thus, a controller system is required. In the literature, there are several known PHPP frequency regulations which have been widely used [10,[24][25][26][27]. The first, the speed-flow controller (SFC) consists to adjust the water flow reaching the hydraulic turbine in order to keep constant turbine speed (frequency constant).…”

Decentralized Adaptive Double Integral Sliding Mode Controller for Multi-Area Power Systems

“…and therefore ( ), ( ), and̃2( ) are bounded. In addition, by combining (22) and (25), it can be obtained thaṫ…”

“…Among these presented control methods, sliding mode control (SMC) is recognized as one of the most efficient tools due to its fast response and strong robustness with respect to uncertainties and external disturbances [20]. Recently, there has been an increasing research interest in the sliding mode based load frequency control for power systems with matched and unmatched uncertainties [20][21][22][23][24]. In [20], a full-state sliding mode controller was developed for load frequency control of power systems.…”

“…In order to improve system dynamic performance in reaching intervals, the decentralized sliding mode controller based on integral switching surface was designed for multi-area interconnected power systems [21]. The scheme of sliding mode control by model order reduction for the LFC problem of micro hydro power plants was addressed in [22]. In [23], the neural-network-based integral sliding mode controller was employed to achieve the LFC problem.…”

Capacitive Energy Storage (CES) Optimization For Load Frequency Control in Micro Hydro Power Plant Using Imperialist Competitive Algorithm (ICA)

“…In previous studies have discussed many frequency control on microhydro, such as [1], [2], [3,4]. Of the several studies, micro-hydro control is still not optimal because it is still based on conventional PID.…”