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Simulation of Wind Speed in the Ventilation Tunnel for Surge Tanks in Transient Processes
Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Peoples R China..
Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Peoples R China.;Design & Res Co Ltd, Changjiang Inst Survey, Planning, Wuhan 430010, Peoples R China..
Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Peoples R China.;Purdue Univ, Dept Agr & Biol Engn, Maha Fluid Power Res Ctr, W Lafayette, IN 47907 USA..
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
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2016 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 9, no 2, UNSP 95Article in journal (Refereed) Published
Resource type
Text
Abstract [en]

Hydroelectric power plants' open-type surge tanks may be built in mountains subject to the provision of atmospheric air. Hence, a ventilation tunnel is indispensable. The air flow in the ventilation tunnel is associated with the fluctuation of water-level in the surge tank. There is a great relationship between the wind speed and the safe use and project investment of ventilation tunnels. To obtain the wind speed in a ventilation tunnel for a surge tank during transient processes, this article adopts the one-dimensional numerical simulation method and establishes a mathematical model of a wind speed by assuming the boundary conditions of air discharge for a surge tank. Thereafter, the simulation of wind speed in a ventilation tunnel, for the case of a surge tank during transient processes, is successfully realized. Finally, the effective mechanism of water-level fluctuation in a surge tank and the shape of the ventilation tunnel (including length, sectional area and dip angle) for the wind speed distribution and the change process are discovered. On the basis of comparison between the simulation results of 1D and 3D computational fluid dynamics (CFD), the results indicate that the one-dimensional simulation method as proposed in this article can be used to accurately simulate the wind speed in the ventilation tunnel of a surge tank during transient processes. The wind speed fluctuations can be superimposed by using the low frequency mass wave (i.e., fundamental wave) and the high frequency elastic wave (i.e., harmonic wave). The water-level fluctuation in a surge tank and the sectional area of the ventilation tunnel mainly affect the amplitude of fundamental and harmonic waves. The period of a fundamental wave can be determined from the water-level fluctuations. The length of the ventilation tunnel has an effect on the period and amplitude of harmonic waves, whereas the dip angle influences the amplitude of harmonic waves.

Place, publisher, year, edition, pages
2016. Vol. 9, no 2, UNSP 95
Keyword [en]
hydroelectric power plants, surge tank, ventilation tunnel, transient process, wind speed, numerical simulation, wave superposition
National Category
Ocean and River Engineering
Identifiers
URN: urn:nbn:se:uu:diva-283792DOI: 10.3390/en9020095ISI: 000371831900020OAI: oai:DiVA.org:uu-283792DiVA: diva2:919601
Available from: 2016-04-14 Created: 2016-04-14 Last updated: 2017-11-30Bibliographically approved
In thesis
1. Hydropower plants and power systems: Dynamic processes and control for stable and efficient operation
Open this publication in new window or tab >>Hydropower plants and power systems: Dynamic processes and control for stable and efficient operation
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

As the largest global renewable source, hydropower shoulders a large portion of the regulation duty in many power systems. New challenges are emerging from variable renewable energy (VRE) sources, the increasing scale and complexity of hydropower plants (HPPs) and power grid. Stable and efficient operation of HPPs and their interaction with power systems is of great importance.

Theoretical analysis, numerical simulation and on-site measurement are adopted as main study methods in this thesis. Various numerical models of HPPs are established, with different degrees of complexity for different purposes. The majority of the analysis and results are based on eight HPPs in Sweden and China.

Stable operation (frequency stability and rotor angle stability) and efficient operation are two important goals. Regarding the stable operation, various operating conditions are analysed; the response time of primary frequency control (PFC) and the system stability of isolated operation are investigated. A fundamental study on hydraulic-mechanical-electrical coupling mechanisms for small signal stability of HPPs is conducted. A methodology is proposed to quantify the contribution to the damping of low frequency oscillations from hydraulic turbines. The oscillations, with periods ranging from less than one up to hundreds of seconds, are analysed.

Regarding the efficient operation, a description and an initial analysis of wear and tear of turbines are presented; a controller filter is proposed as a solution for wear reduction of turbines and maintaining the frequency quality of power systems; then the study is further extended by proposing a framework that combines technical plant operation with economic indicators, to obtain relative values of regulation burden and performance of PFC.

The results show that the coupling between the hydraulic-mechanical subsystem and the electrical subsystem can be considerable and should be considered with higher attention. Effectiveness and applicability of different numerical models are shown, supplying suggestions for further model optimization. For the influence from power systems on HPPs, the dynamic processes and corresponding control strategies of HPPs under diverse disturbances and requirements from power systems are addressed. For the influence from HPPs on power systems, quantifications of frequency quality and the hydraulic damping are conducted utilising proposed methodologies.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. 140 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1494
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-318470 (URN)978-91-554-9871-9 (ISBN)
Public defence
2017-05-19, Polhemsalen, Ångtröm 10134, Lägerhyddsvägen 1, Ångströmlaboratoriet, Uppsala, 13:15 (English)
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Available from: 2017-04-28 Created: 2017-03-24 Last updated: 2017-05-05

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Yang, Weijia

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