Pumped Storage Projects Research Articles

Considerations for the static and seismic design of pumped storage reservoirs in soft soils and seismic environments

AbstractFor recent hydroelectric pumped storage projects, the construction of embankment dam structures on alluvial deposits consisting of exceptionally soft soil and in areas with high seismicity was required. This contribution shares experiences and challenges from the static and seismic design of embankment dam structures and ground treatment options. Finite element‐based static and seismic analyses using the Hardening Soil Small Strain model (HSS) showed that preconsolidation has clear benefits compared to stone columns for ground improvement purposes. Regardless of general advantages of surface sealing systems for frequent and rapid impoundment level changes, it was found that clay core design options perform very well under seismic loading conditions and even better than surface‐sealed structures. Seismic ground and structure response analyses involving soft soil considering shear strain‐dependent stiffness degradation revealed that deamplification is expected in contrast to the rule‐of‐thumb amplification approaches enshrined in many seismic design guidelines and codes. It was found that this effect increases with seismic magnitudes and that saturation of peak ground acceleration (PGA) takes place. This results in relatively moderate structure excitations even under significant dynamic excitation.

Design techniques for improving energy performance and S-shaped characteristics of a pump-turbine with splitter blades

The development of high-head pumped-storage projects presents various opportunities and challenges. One challenge is the operational stability of pumped-storage power plants, which is closely associated with the characteristics of pump-turbines. In this study, the design and experimental verification of the hydraulic performance of a pump-turbine runner with splitter blades are investigated. The effects of several main parameters on the performance curve and S-shaped characteristics of pump-turbines in turbine mode are examined via numerical simulation. Subsequently, model tests are conducted to validate the improvements in the performance curve, including a comparison of the S-shaped characteristic curve at a constant guide vane opening and under the same initial conditions. An emergency load rejection test based on the same guide vane closing scheme is performed to verify improvements in transient pressure in the spiral case, draft tube, and rotational speed. The results confirm the enhancement in the S-shaped characteristics and transient global parameters of the splitter blade design. Furthermore, a reduction in pressure pulsation intensity in the vaneless space during off-design conditions is confirmed.

Study on market mechanisms for participation of small-scale hydropower clusters in electricity energy and ancillary services

The problem of large-scale distributed new energy consumption is highlighted under the double carbon target. Based on the existing distributed small hydropower and local hydrological and geographical conditions, the pumping-storage linkage function of distributed small hydropower can be realized through small-scale transformation according to local conditions, which can significantly reduce the construction cost and improve the profitability of the power station. The development of small hydropower to pumped storage can effectively enhance the flexible regulation capacity of the power grid. Based on an analysis of the investment environment, profitability and option characteristics of small hydropower to pumped storage projects, this paper conducts a study on the operational mechanism of hydropower participation in the electricity energy market and auxiliary services market to provide support for small hydropower to pumped storage investments in the new situation.

Economic evaluation and optimization model of pumped storage project under the background of new power system construction

Pumped storage is the main regulating power supply of power system. It is more urgent to build a new power system with new energy as the main body. In order to accelerate the development of pumped storage projects, it is urgent to improve the economic evaluation method of pumped storage projects under the background of new power system construction. Firstly, the value of pumped storage in ensuring the safety and reliability of the new power system, improving the utilization level of renewable energy, and improving the performance of power generation, distribution and consumption of the new power system is analyzed. Then, the economic evaluation model of pumped storage project is optimized, and an index system covering value contribution to the new power system, financial profitability and anti risk ability is constructed. Finally, through the comparative analysis of pumped storage and coal-fired power generation projects, the scientificity and rationality of the model are verified.

Effect of outer edge modification on dynamic characteristics of pump turbine runner

It is currently in the period of high-speed construction of pumped storage projects. However, the problems caused by vibration of pump turbine units, especially the runners, are very serious. It is of great significance to study the dynamic characteristics of pump turbine runner for the safety and stability of power station. In this paper, the natural modes of a pump turbine runner in the air and in the flow channels are calculated by numerical method. The influence and mechanism of the outer edge modification on the natural frequencies of the runner are studied. The results show that, for the object studied in this paper, the frequency of most modes will be decreased by thickening the outer edge. The frequency change can be attributed to two aspects, one is the change of the mass and the stiffness of the runner, and the other is the change of added mass of the water. Furthermore, the main mechanism of outer edge modification affecting the added mass coefficient is that the height of the radial clearance is changed.

Influence of hydraulic characteristics on transient behavior of ultra-high head pump turbine

Pump turbines with ultra-high head or low specific speed have typically pronounced “S” characteristics in generation mode, which usually leads to a very challenging situation regarding the transient behavior, especially when it is not adequately considered in the power plant layout. Though some countermeasures, e.g. asynchronous guide vane closing or fast MIV closing, can be taken in the late stage to mitigate the problem, nowadays the customers are more in favour of a solution on root, i.e. improving the “S” characteristics by optimizing the hydraulic design of pump turbine during design stage. Recently Dongfang has successfully developed several pump turbines with a head range from 580m up to 750m. An important consideration during the development is to find out a compromise between hydraulic performance and transient behavior. This paper presents how the hydraulic design influences the “S” characteristics and subsequently the transient behavior, based on the investigations performed and improvements obtained through these pumped-storage projects.

Pumped-storage in Bulgaria – Developments, Current Situation and Some Perspectives

The objective approach requires that the hydropower development cannot be analyzed outside the economical and overall national development of a particular country during a considered time period. Yet the current presentation addresses exclusively the Hydropower development in Bulgaria, and moreover, concentrated only on the features of pumped-storage as a reliable and still highly competitive energy storage technology.The pumped-storage as part of the hydropower development in Bulgaria and the situation as in 1989 are introduced. The overall development in Bulgaria after November 1989 and its impact on both running and future hydropower and pumped-storage projects are shortly presented. Particular features of the current situation are outlined. Furthermore, special attention is paid to the national legislative environment in the frame of the crucial policies, strategies and directives of the European Union.Finally, some ideas and project possibilities for the use of the still available pumped-storage potential in Bulgaria are discussed in more detail. The work ends with conclusions on the Bulgarian hydropower development with respect of pumped-storage mainly after 1989. Needed research activities in particular fields are identified for a possible future pumped-storage development in Bulgaria as an EU member state in the sense of global electricity market conditions.

Monte Carlo Simulation for Economic Analysis of Hydropower Pumped Storage Project in Nepal

Investments in hydropower pumped storage projects (PSP) are subjected to a high degree of uncertainty. In addition to normal uncertainties in hydropower schemes, the profit of a pumped storage scheme is dependent on the margin between power prices for buying and selling, which is difficult to predict without a power purchase agreement (PPA). A PSP without a PPA and without known construction costs requires quantification of the uncertainties in order to make qualified decisions before investing in such projects. This article demonstrates the advantages of using Monte Carlo (MC) simulations as a tool in the economic analysis of PSPs. The method has been tested on a case study, namely the Tamakoshi-3 Hydropower Project (HPP) in Nepal. The MC method is used to calculate the probability distribution of the net present value of installing reversible units in the Tamakoshi-3 HPP. The calculations show that PSPs may be profitable in Nepal, given a beneficial development of the power market. The MC method is considered to be a useful tool for economic analysis of PSPs. In this case study of installing reversible units in the Tamakoshi-3 HPP, there are many uncertainties, which the MC simulation method is able to quantify. Hydro Nepal; Journal of Water, Energy and Environment Vol. 12, 2013, January Page: 39-44DOI: http://dx.doi.org/10.3126/hn.v12i0.9031 Uploaded Date : 10/29/2013

Competitive pumped‐storage projects with vertical pressure shafts without steel linings / Konkurrenzfähige Pumpspeicherwerkprojekte dank ungepanzerter, vertikaler Druckschächte

AbstractFor the highly loaded pressure tunnels and shafts that are used for the extension of storage power plants with pumped storage and to increase installed capacity, alignments of the waterway system with high overburden are of great importance from the economical and safety points of view. With the development of the raise‐boring method, vertical pressure shafts can now be drilled up to 800 m in one step.Considering rock cover, the use of vertical pressure shafts can enable optimal alignments. If the vertical shaft is located deep enough in the rock mass and safety against hydraulic jacking can be ensured, no steel liner is required in the shaft as long as rock permeability is low, and a reinforced concrete lining is sufficient. This is designed in order to limit crack widths and thus keep water losses below acceptable values. In view of highly increasing steel prices, such a concept results in economic and competitive pumped‐storage projects.Bei hochbeanspruchten Druckstollen und Druckschächten, wie diese bei der Erweiterung von Speicherkraftwerken mit Pumpspeicherwerken und durch Leistungserhöhungen vorkommen, sind tiefliegende Linienführungen der Triebwassersysteme aus wirtschaftlichen und sicherheitstechnischen Gründen von größter Bedeutung. Mit der Entwicklung des Raise‐Boring‐Verfahrens können heute Vertikalschächte bis gegen 800 m in einer einzigen Etappe ausgeführt werden. Dadurch ergeben sich bezüglich Felsüberdeckung optimale Linienführungen. Falls der Schacht genügend tief im Gebirge angeordnet wird und somit die Sicherheit gegen hydraulischen Gebirgsbruch gewährleistet ist, kann bei wenig durchlässigen Felsformationen auf eine Stahlpanzerung verzichtet werden. Eine bewehrte Betonauskleidung ist ausreichend, deren Bewehrung so bemessen ist, dass die Rissweiten und somit die Wasserverluste auf zulässige Werte beschränkt werden. Anbetracht der stark angestiegenen Stahlpreisen führt dieses Konzept zu wirtschaftlichen und konkurrenzfähigen Pumpspeicherwerkprojekten.

Vibration Behavior and Dynamic Stress of Runners of Very High Head Reversible Pump-turbines

In the development of very high head pumped storage projects, one of the critical problems is the strength of pumpturbine runners. Data obtained by stress measurements of high head pump-turbine runners indicated that dynamic stress due to the vibration of runner might be detrimental, possibly to cause fatigue failure, if the runner were designed without proper consideration on its dynamic behaviour. Numerous field stress measurements of runners and model tests conducted with hydrodynamic similarity revealed that the hydraulic excitation force developed by the interference of rotating runner blades with guide vane wakes sometimes would induce such heavy vibration of runner. Theoretical and experimental investigations on both the hydraulic excitation force and the natural frequencies of runner have been conducted to explore this forced vibration problem.

Rating Limits for Generator/Motors for High Head Pumped Storage Projects

Economics of scale can assume unusual importance in the case of pumped storage schemes involving underground reservoirs. The paper proposes an approach to define the presently attainable maximum ratings for generator/motors in the 514-1200 RPM speed range. Prelimimary results are presented as well as directions for confirming and/or extending these limits.

Rating Limits for Generator/Motors for High Head Pumped Storage Projects

Rating Limits for Generator/Motors for High Head Pumped Storage Projects

Variable Frequency Starting Equipment for Pumped Storage Projects

This paper describes the variable frequency starting equipment for the Bath County Pumped Storage Project now being built by Virginia Electric and Power Company. The principle of operation and the construction are discussed, as well as special considerations with grounding the generator/motor during operation of the starting equipment.

Survey of pumped storage projects in the united states and Canada to 1975

Survey of pumped storage projects in the united states and Canada to 1975

Pumped Storage: Its Significance as an Energy Source and Some Biological Ramifications

Abstract Pumped storage hydroelectric projects provide an economic way of meeting peak energy needs in electric power systems. Types and locations of pumped storage projects and their basic engineering and operations are described together with the biological impacts common as well as unique to this form of power generation. The rapid increase in the number of pumped storage projects during the last 16 years and projected future construction indicate a serious need for expanded studies to provide for better design features and reduced environmental damage. Biological studies underway and those needed are described and discussed.

Biological Considerations of Pumped Storage Development

The decision to build pumped storage projects must be made with the knowledge that there will be changes in the environment. Many of the biological considerations of pumped storage are quite similar to those of the more conventional types of reservoir development and operations. There are special considerations which deserve the attention of workers in fisheries and related aquatic sciences. (RRB)

Reservoirs for pumped storage

Pumped storage projects involve major civil engineering works costing tens of millions of pounds but are nevertheless an efficient way of storing energy and economically a better method of meeting peak loads than building bigger generating stations. Because they require special environments, reservoirs for pumped storage raise difficult problems in engineering geology. Such schemes operate with maximum efficiency with heads of the order of 1000 ft and relatively short hydraulic systems. There is no need for natural catchment at the upper reservoir, since water is pumped, but for the same reason the engineering geologist must ensure that minimum leakage will occur. As high-level, small corrie/cwm basins are likely to be used, the upper reservoir site may need to be topographically and geologically suitable for the high dam required to gain capacity. The limitations of very brief starting time and high output impose severe limits on the lengths of tunnels, etc. and on the position of the power station in the system. The geologist, therefore, has not the same freedom to suggest geologically better tunnel routes and power station sites, and has to give an opinion whether the rocks present are suitable for large tunnels and underground power station chambers. At the lower reservoir site, unless there is a considerable natural inflow, leakage must again be reduced to a minimum. Moreover, as the lower reservoir is often in developed areas, very careful account must be taken of possible alterations to the water table and of the results of large and frequent

Pumped Storage: State-of-the-Art

The many special problems involved in pumped storage power projects are of widespread interest to the profession. A panel discussion program was organized which consisted of a cross section of experienced individuals and it was scheduled so that it would follow a session on pumped storage projects at the 1970 ASCE Memphis Conference. The panelists were given a list of topics in advance to assist in formulating their comments.

Penstocks for Six Pumped Storage Projects

High head pumped storage plant designs have required drastic changes in steel plate specifications and welding procedures for penstocks and tunnel liners. Salient data are reviewed for six penstock projects at Lewiston, NY; Smith Mountain, VA; Oroville, CA; Yards Creek, NJ; Cabin Creek, CO, and Seneca, PA. Previous plate material specifications for penstocks were made obsolete by revisions in 1968 and 1969 ASTM standards. Design unit stress maximum limits of less than one-third of tensile strength or two-thirds of yield strength have important precedents. Testing decisions require evaluation of widely varying factors. In penstock fabrication and welding specifications, it is logical to take advantage of ASME Pressure Vessel, Section VIII, Division 1, applicable clauses. Future closer cooperation will be required between consulting or owner engineers and experienced technical representatives of penstock fabrication and construction companies in order to obtain economical designs specifications for penstocks.

Cabin Creek Pumped Storage Hydroelectric Project

The Project consists of two reservoirs with a maximum head differential of 1,226 kw pump-turbine units. The upper reservoir is formed by a 210 ft high rock fill dam with a concrete facing with crest 11,202 ft above sea level. The dam at the lower reservoir is a combination earth and rock fill dam 95 ft high with sloping impervious core and upstream blanket. Geologic foundation conditions at each dam are described along with cross sections, elevations and outlines of construction specifications. The service requirements for dams for pumped storage projects are much more severe than most dams because of rapid daily drawdown and refill. The dams were monitored during and following construction. Records of deflection, settlement and seepage measurements are presented. In addition, some of the miscellaneous project features including erosion control, icing, and some of the project problems and solutions are described.