scholarly journals Protective Reactance in Large Power Stations

1914 ◽  
Vol XXXIII (1) ◽  
pp. 23-55 ◽  
Author(s):  
James Lyman ◽  
Allen M. Rossman ◽  
Leslie L. Perry
Keyword(s):  
1914 ◽  
Vol 33 (2) ◽  
pp. 141-163 ◽  
Author(s):  
James Lyman ◽  
Allen M. Rossman ◽  
Leslie L. Perry
Keyword(s):  

Author(s):  
Shuhong Liu ◽  
Xiaojing Wu ◽  
Yulin Wu

Francis turbine is widely employed in large scale hydro-power stations in the world with main characteristics of efficiency, stability and cavitation. In practical establishment, each large power station must develop a new Francis turbine for its special natural condition and requirement, such as higher efficiency for utilization of natural resources. CFD has been developed greatly and helped a lot in hydraulic design stage of the turbine. In this paper, firstly, a new RNG k–ω turbulence model is proposed based on the RNG k–ε model, which brings the nonlinear term of the mean fluid flow transition to the ω equation in the original k–ω model. And, this RNG k–ω model has been used to predict the energy performances for Francis turbine. Then, the flow diagnosis method in the turbine runner based on vorticity parameters is presented, following the detailed flow behavior revealed. Finally, the simulation results for different model Francis turbines have been compared and analyzed for optimizing the energy performances of the turbine. The model test results indicate that the efficiency of hydraulic turbine has been improved from 93.6% to 94.5%.


2020 ◽  
Vol 68 (9) ◽  
pp. 790-803
Author(s):  
W. H. Wellßow ◽  
P. Hinkel ◽  
M. Zugck ◽  
C. Dumas ◽  
S. Hilgers ◽  
...  

AbstractIn Germany, the installed capacity of renewables exceeds the maximum load by far and the transmission task has changed from high-wind locations in the north to the economically strong south. In addition, the system inertia is reduced due to the decommissioning of large power stations. This leads to a higher probability of blackouts and a challenging restoration process. Operation during restoration differs strongly from normal. Besides other effects, the grid frequency is very sensitive to active power imbalances. An accurate power forecast of re-supplied feeders is required to estimate dynamic frequency deviations. Models for cold load pick-up (CLPU) and fluctuating renewable energy sources (RES) infeed are presented. For the coordination between Transmission system operators (TSO) and Distribution system operators (DSO) a clear and structured process is proposed to minimize the communication effort. Power system restoration (PSR) simulations are carried out and the results are presented.


2019 ◽  
Vol 11 (6) ◽  
pp. 1621 ◽  
Author(s):  
Stephan Bosch ◽  
Lucas Schwarz

The implementation of many small power stations compensates the closing of powerful large power plants as part of the German Energy Transition is compensated. It is unclear how site decisions are made, which actors are involved, and which economic, ecological, and social consequences occur. The quantitative study consists of a written postal survey of renewable energy plant operators, concerning central aspects of project development. The study found strong regional disparities concerning the entrepreneurial behavior of plant operators of renewable energies, a low importance of socio-institutional and socio-cultural parameters, a great relevance of micro-social environment during site planning of renewable energy plants, and that plant operators are highly influenced by economic and individual desires. It may be concluded that the perspectives operators have on the Energy Transitions must be more systematically included into the discourse regarding the sustainable deployment of renewable energies, as they reveal significant disparities with topics that are emphasized by the public (e.g., landscape aesthetic, citizens’ participation). It was shown that the challenges and problems that arise in the context of regional energy transformation cannot be generalized beyond regional circumstances; rather, they must be regarded as specific regional phenomena that have to be overcome by means of regionally adapted energy concepts.


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