Experimental Grey Box Model Identification and Control of an Active Gas Bearing

Author(s):  
Lukas Roy Svane Theisen ◽  
Fabián G. Pierart ◽  
Henrik Niemann ◽  
Ilmar F. Santos ◽  
Mogens Blanke
1993 ◽  
Vol 32 (7) ◽  
pp. 1275-1296 ◽  
Author(s):  
James B. Rawlings ◽  
Stephen M. Miller ◽  
Walter R. Witkowski

Author(s):  
Scott Dana ◽  
Joseph Yutzy ◽  
Douglas E. Adams

One of the primary challenges in diagnostic health monitoring and control of wind turbines is compensating for the variable nature of wind loads. Given the sometimes large variations in wind speed, direction, and other operational variables (like wind shear), this paper proposes a data-driven, online rotor model identification approach. A 2 m diameter horizontal axis wind turbine rotor is first tested using experimental modal analysis techniques. Through the use of the Complex Mode Indication Function, the dominant natural frequencies and mode shapes of dynamic response of the rotor are estimated (including repeated and pseudo-repeated roots). The free dynamic response properties of the stationary rotor are compared to the forced response of the operational rotor while it is being subjected to wind and rotordynamic loads. It is demonstrated that both narrowband (rotordynamic) and broadband (wind driven) responses are amplified near resonant frequencies of the rotor. Blade loads in the flap direction of the rotor are also estimated through matrix inversion for a simulated set of rotor blade input forces and for the operational loading state of the wind turbine in a steady state condition. The analytical estimates are shown to be accurate at frequencies for which the ordinary coherence functions are near unity. The loads in operation are shown to be largest at points mid-way along the span of the blade and on one of the three blades suggesting this method could be used for usage monitoring. Based on these results, it is proposed that a measurement of upstream wind velocity will provide enhanced models for diagnostics and control by providing a leading indicator of disturbances in the loads.


Author(s):  
V.S. Zaburdayev ◽  
◽  
S.N. Podobrazhin ◽  

Conditions are given concerning the development of methane-bearing coal seams in Russia, the chronology of injuries from explosions and outbreaks of methane-air mixtures at the Russian mines for a quarter of a century of developing coal seams at the nine deposits. The emergency was studied in 174 mine incidents, which occurred mainly at the mines of Kuzbass, Vorkuta coal deposit, Eastern Donbass, Chelyabinsk basin, Primorye and Sakhalin. Emergency objects - excavation areas, preparation faces and mined-out areas of the mines. The sources of ignition of methane-air mixture are drilling and blasting works in the faces, malfunctioning of electrical equipment, frictional sparking, endogenous fires, and smoking in the mines. The most injury-risk for methane are steep and steeply inclined mines. The need in the scientific substantiation of the decisions taken for prevention or reduction of the methane injury-risk at the mines is noted in the article. An important role is assigned to the choice of ways to achieve this goal considering the geological and mining conditions of the development of gas-bearing coal seams. As an example, the conditions, methods, and parameters of mining operations at the excavation areas of four mines are given, where occurred the catastrophic explosions of methane-air and methane-dust-air mixtures. The reasons are gross violations of safety rules during mining operations, incompetence of the mine engineering personnel, design, and control organizations in matters of safety during the underground work at the gas-hazardous mines with an extensive network of workings. This resulted in the death of miners and mine rescuers, the destruction of mine workings, equipment and devices, underground fires. Recommendations are given for reducing the level of methane injury-risk at the methane-rich mines.


2010 ◽  
Vol 43 (10) ◽  
pp. 117-122 ◽  
Author(s):  
Jirí Rehor ◽  
Vladimír Havlena

1994 ◽  
Vol 27 (8) ◽  
pp. 1617
Author(s):  
S. Carabelli ◽  
C. Greco

Sign in / Sign up

Export Citation Format

Share Document