Modeling of an Extraction Steam Turbine and Speed Control System Design
Abstract
Steam-driven power plants essentially convert mechanical energy into electrical energy by using steam turbines. It is imperative to control the speed of the turbines as the frequency of the power system depends on it. This paper presents a model of a steam turbine containing three steam extractions from the intermediate-pressure section and four extractions from the low- pressure section. The underlying methodology for modeling is the continuity equation of a steam vessel. As the input variables, the model uses the valve opening degree of different valves, namely high-pressure valve, reheater valve, intermediate-pressure steam extraction valve and low-pressure steam extraction valve. The model behavior is observed against each input variable. It is then subsequently used to design the speed control system of the steam turbine using the proportional and proportional-integral controllers. The response of the speed control system is analyzed for both types of controllers and different valve openings. Simulation results demonstrate that the proposed model is suitable to study the dynamic behavior of an extraction steam turbine and for the feedback control system design.References
M. Bennauer, E.G. Egener, R. Schlehuber, H. Werthes and G. Zimmer, “Automation and control of electric power generation and distribution system: Steam turbinesâ€, Control Syst. Robot. Autom., vol. 18, pp. 261-271, 2009.
G. Zimmer, “Modelling and simulation of steam turbine processes: Individual models for individual tasksâ€, Math. Comp. Model. Dyn. Syst., vol. 14, pp. 469-493, 2008.
R.T. Byerly, O. Aanstad, D.H. Berry, R.D. Dunlop, D.N. Ewart, B.M. Fox, L.H. Johnson and D.W. Tschappat, “Dynamic models for steam and hydro turbines in power system studiesâ€, IEEE Trans. Pow. App. Syst., vol. 6, pp. 1904-1915, 1973.
M. Dulau and D. Bica, “Mathematical modelling and simulation of the behaviour of the steam turbineâ€, Procedia Technol., vol. 12, pp. 723–729, 2014.
M. Dulau and D. Bica, “Simulation of speed steam turbine control systemâ€, Procedia Technol., vol. 12, pp. 716 – 722, 2014.
X. Luo, B. Zhang, Y. Chen and S.P. Mo, “Modeling and optimization of a utility system containing multiple extractions steam turbinesâ€, Energy, vol. 36, pp. 3501-3512, 2011.
A. Chaibakhsh and A. Ghaffari, “Steam turbine modelâ€, Simul. Model. Pract. Theor., vol. 16, pp. 1145–1162, 2008.
H. Rusinowski and M. Plis, “Mathematical model of a steam turbine for the thermal diagnostics systemâ€, Proc. Int. Carpath. Ctrl. Conf. (ICCC), Tatranska Lomnica, Slovakia, pp. 630-634, 2016.
K. Kulkowski, M. Grochowski, K. Duzinkiewicz and A. Kobylarz, “Nuclear power plant steam turbine: Modeling for model based control purposesâ€, Appl. Math. Model., vol. 48, pp. 491-515, 2017.
S. Dettori, V. Colla, G. Salerno and A. Signorini, “Steam turbine models for monitoring purposesâ€, Energy Procedia, vol. 105, pp. 524-529, 2017.
S. Lu and B.W. Hogg, “Dynamic non-linear modeling of power plant by physical principles and neural networksâ€, Int. J. Elect. Pow. Energy Syst., vol. 22, pp. 67-78, 2000.
E.J. Farmer and B.G. Liptak, Process Control and Optimization: Steam turbine controlsâ€, 4th ed., vol. 2, Washington D.C., CRC Press, pp. 2137-2151, 2006.
W. Aleite, K. Ara, J. Berggren, A. Faya and C.G. Forstner, “Modern Instrum. and Control for Nuclear Power Plants: A guidebookâ€, International Atomic Energy Agency (IAEA), Vienna, Technical Reports Series, no. 387, 1999.
K. Kulkowski, A. Kobylarz, M. Grochowski and K. Duzinkiewicz, “Dynamic model of nuclear power plant steam turbineâ€, Archive Control Sci., vol. 25, pp. 65-86, 2015.
B. Vahidi, M.R.B. Tavakoli and W. Gawlik, “Determining parameters of turbine’s model using heat balance data of steam power unit for educational purposesâ€, IEEE Trans. Pow. Syst., vol. 22, pp. 1547–1553, 2007.
R. Rajan, P.M. Salih and N.A. Kumar, “Speed controller design for steam turbineâ€, Int. J. Adv. Res. Electr. Electron. Instrum. Eng., vol. 2, pp. 4400-4409, 2013.
