Effect of Concrete Cracks on Dynamic Characteristics of Powerhouse for Giant-Scale Hydrostation

With the increase of capacity and size of the hydro-generator unit, the spiral case becomes a more super-giant hydraulic structure with very high HD value, where H and D denote water head and maximum intake diameter of spiral case, respectively. Due to the induced lower stiffness by the more giant size and adverse operation conditions, dynamic performances of the powerhouse and the supporting structure for the giant units have become more important and attracted much attention. If the manner of steel spiral case embedded directly in concrete is adopted, on some locations of the concrete surrounding the spiral case, distributed and concentrated cracks will emerge due to high tensile stress. Although the concrete is reinforced well to control the maximum crack width, definitely these cracks will reduce the local and entire stiffness of the powerhouse. Under dynamic loads such as hydraulic forces including water pressure pulsation in flow passage acting on the structure, effect of the cracks on the dynamic characteristics of the local members and entire structure needs to be evaluated. However, research on this subject is few in hydroelectric engineering. In this paper, Three-Gorge Project was taken as an example to evaluate effect of such cracks on natural frequencies and the vibration responses of the powerhouse under hydraulic and earthquake forces in detail. Results show that cracks only reduce the local structural stiffness greatly but have little effect on the entire powerhouse especially the superstructure; vibrations of powerhouse with cracks in concrete surrounding the spiral case are still under the design limits. Results in this paper have been verified by practice of Three-Gorge Project.

High Slope Stability of Diversion Power System Intake of Jinchuan Hydropower Station

The excavated height of the left bank slope of the diversion power system intake in Jinchuan hydropower station is about 16o m. The stability and safety of the slope during construction and its operation/utilization become one of the most important geological engineering problems. At the same time, it is also crucial to select a safe and economic excavation gradient for the construction. We studied the problem of how to select a safe and economic slope ratio by analyzing the geological condition of the high slope, including the lithology, slope structure, structural surface and their combinations, rock weathering and unloading, hydrology, and the natural gradient. The study results showed that the use of an excavation gradient larger than the gradient observed during site investigation and the gradient recommended in standards and field practice manuals is feasible. Then, we used the finite element method and rigid limit equilibrium method to evaluate the stability of the excavation slope under natural, rainstorm and earthquake conditions. The calculated results showed that the excavated slope only has limited failure, but its stability is greatly satisfactory. The research findings can be useful in excavation and slope stabilization projects.

A Technical Review of Hydro-Project Development in China

This paper summarizes the development of hydro-projects in China,blended with an international perspective.It expounds major technical progress toward ensuring the safe construction of high dams and river harnessing,and covers the theorization of uneven non-equilibrium sediment transport,inter-basin water diversion,giant hydro-generator units,pumped storage power stations,underground caverns,ecological protection,and so on.

A Physical Simulation Test for the RockBurst in Tunnels

According to the test results of the physical and mechanical properties of similar materials in various quality mixture, a type of material with obvious tendency of rockburst was selected to produce a large-size model to simulate rockburst phenomena in tunnels. The prototype model comes from a typical section of diversion tunnels in Jinping Hydropower Station in China. The simulation of excavating tunnels is carried out by opening a hole in the model after loading. The modeling results indicated that under the condition of normal stresses in the model boundaries the arch top, spandrel and side walls of the tunnel produced an obvious jump reaction of stress and strain and the acoustic emission counts of the surrounding rock also increased rapidly in a different time period after the "tunnel" excavation, showing the clear features of rockburst. The spalling, buckling and breaking occurred in the surrounding rock of model in conditions of over loading. It is concluded that the modeling tunnel segment in Jinping Hydropower Station is expected to form the tensile rockburst with the pattern of spalling, buckling and breaking.

Quo Vadis Archimedean Turbines Nowadays in Greece, in the Era of Transition？

According to recent hydropower inventories, the first aim of this paper is to prove that Greece is a real ＂Archimedean Soft Small Hydro Development Terra Incognita＂. It is a country in the Era of Transition of nowadays, having an important unexploited hydropower potential of several TWh and thousands of MW. The second goal is to present the results of rediscovering the old screw pumps and the always-modern Archimedean cochlear screw ideas as a series of soft hydropower turbines with inclined axis rotors and floating spiral screw devices. By following the similarity methodology, a few small-scale models of cochlear rotors were designed, developed and tested in an Armfield hydraulic channel. The conventional and unconventional, low or zero-head screw turbines, could efficiently harness the important and unexploited Greek small potential and kinetic hydraulic energy of all the natural watercourses, the man-made open urban or rural channels and the most important tidal or sea currents, producing useful green electricity. The very promising low-head hydropower inventory of Greece, the preliminary experimental results and the research studies of cochlear projects in watercourses, hydraulic works, tidal conditions of Euripus Strait and in the mysterious ＂Sea River Current of Cephalonia＂, seems to give a good answer to the question ＂Quo Vadis Archimedes nowadays in Greece, in the Era of Transition？＂.

Filtration Features in the Base of the Bratsk HPP （Hydroelectric Power Station） Concrete Dam

The design protection of the base of the Bratsk HPP （Hydroelectric Power Station） dam from filtration coming from the water reservoir included the arrangement of several cement-grout curtains and the system of drainage holes in the 2nd and 4th columns. During operation, increased hydrostatic back pressure at the base of the dam was found, which indicated the low efficiency of the base design protection. To reduce back pressure B. E. Vedeneev Hydro Technic Institute proposed the device of “advanced” drainage holes from the cement-grout gallery near the upstream face. The implementation of the proposal in a number of sections of the dam has led to a decrease in back pressure, but affected filtration in the drainage system, increasing it significantly. The article examines filtration features of “advanced” drainage holes and their dependence on the severity of winters. The spread of the practice of “advanced” drainage in other sections of the dam requires caution and further investigations of the nature of filtration.

The principle of minimization of the equivalent load for design of launching vertical shiplift

Launching vertical shiplift is a type of shiplifts which have the advantages in characteristics of dynamics and statics, safety and simplicity in operation. But their applications are limited as the scales of mechanical equipments are too large. This paper puts forward the principle of minimization of the equivalent load for the general layout design of launching vertical shiplifts, based on the analysis of the load probability of the main hoists and their key mechanical equipments. The principle aims at determining the optimal weight of counterweight so that the equivalent loads of the main hoists of shiplifls are minimized, and larger ships are permitted to pass through. The theory and method presented in this paper have been applied in the design of the first step and third step shiplifts of the Goupitan Hydro Power Station. This has resulted in the breakthrough of the design and manufacture of launching vertical shiplifts so that the ships with tonnage of 500 t can pass through hydro dams for this type of shiplifts, comparing with the largest launching shiplift in Yantan Hydro Power Station with the 250 t shiplift.

Towards a Sustainable Development of Small Hydropower Plants, from Valley of Sperchios River to Mount Olympus

The mountainous region of Fthia, identified with the Valley of Sperchios River, in Central Greece, is rich in small watercourses and generously blessed with water and abundant water falls. The geographical configuration of Olympus and Fthia＇s mounts and the hydraulic singularities of drained lakes Askouris in Olympus, favour the installation of series of sustainable small hydroelectric plants. The present action consists of a serious effort towards the systematic sustainable small hydropower exploitation of Fthia＇s and Olympus hydraulic potential, including the Archimedean hydropower perspectives of Sperchios River.

Performance Analysis of the Aeration Valves and Its Protections at the Generating Units in ITAIPU Hydroelectric Power Plant

With the growing energetic need present in the world, it is increasingly necessary for the researches and facilities to seek a better use of renewable natural resources. This paper is applied in the study of the performance of the aeration system of the Francis turbines present in Itaipu Hydroelectric Power Plant. When a Francis turbine operates off its optimal conditions, a vortex is formed inside the draft tube that, besides produces cavitation and pressure fluctuations, can pulse at frequencies with risk of resonance with hydraulic system, producing efforts and vibrations that may cause structural failures in the turbines, generators and civil parts of the power house. These damaging effects can be reduced using atmospheric aeration of the turbines. Because of this, the availability and effectively of the aeration system is fundamental to smooth the behavior of the turbines, helping preserve the health of the power plant. An analysis of the performance of the aeration system will be done using maintenance records and disturbances analysis reports （RAP）, allowing verification of the operating conditions of the turbine and fatality of water inlet in air pipes. Through the improvements detected, it is possible to reduce machine stoppages by tripping, thus increasing the availability of the turbines.

An Empirical Study of Characteristics of the Spatial Distribution of Taobao Travel Intemet Store

The development of tourism depends on the development of physical stores and the level of economic development of tourism, distribution, and analysis of the main research shop this virtual store. In this study, based on China＇s largest e-commerce website --- Taobao C2C data to the country＇s 31 provinces, autonomous regions and municipalities （excluding Hung Kong, Macao and Taiwan） for the study, and regression analysis using ArcGIS software tools, from the provincial tourism C2C e-commerce Factors affecting the development of conduct Regression analysis, and An Empirical Study of the geographical distribution of the electrons. The results showed that the development of China＇s tourism e-commerce C2C level and the level of tourism development and local economic development are very relevant. The degree of economic development and the level of development of tourism and travel Taobao C2C e number of shops are highly correlated.

Experimental Study on a Cascade Flapping Wing Hydroelectric Power Generator

A hydroelectric power generator, which is able to extract the water flow energy from the hydroelastic response of an elastically supported rectangular wing, is experimentally investigated. An electric motor is used to excite pitching oscillations of the wing. Both the wing and the electric motor are supported by leaf springs which are designed to work both as a linear guide for the sway oscillations and as elastic elements. The wing mass in sway direction necessary to achieve a hydroelastic response is obtained by utilizing a mechanical snubber mechanism. The appropriate load to generate electricity is provided by magnetic dampers. In the previous paper, the generating power rate and the efficiency were examined through the experiments with a single wing model, and the feasibility of the flapping wing hydroelectric power generator was verified. In this paper, the influence of the neighboring wings is examined by using two experimental apparatuses, with the intention of achieving a practical cascade wing generator. Tests revealed that the cascade moving in-phase with the neighboring wings at narrower intervals has a higher rate of electric power generation.

Profit-Based Optimal Operation of a Head-Dependent Hydroelectric Power Station in the Bilateral Market

Deregulation and liberalization of electric power industry, among other things, has created new requirements for the market participants. The power system engineer, operator, and, in general, the market participants are being faced with requirements for which they do not have adequate training and the proper software tools. In this framework, among others, a pure hydro-generation company has to operate its hydro units, throughout the operating day, trying to fulfill the market clearing schedule or a bilateral contract, and modify the program in the intra-day energy markets if necessary （or more suitable） as real-time operation is getting closer. In this scenario the objective is to maximize the hydroelectric power plant profit from selling energy in the spot market or by means of bilateral contracts. In this paper the optimal operation of a head-dependent hydroelectric power station in bilateral market-short-term hourly hydro resource scheduling for energy is obtained.

Development of a Renewable Energy Based DC Excitation System in a Micro Hydro Power Plant

MHPPs （micro hydro power plants） have become prominent in hydropower plants as a solution to provide the energy demands of the grid. In this study, a new hybrid renewable energy based DC excitation system for synchronous generator in the developed MHPP system is introduced. Proposed hybrid DC excitation system consists of solar ＆ hydrogen energy based power generating systems. Hybrid renewable energy based system is used for the excitation of the synchronous generator in the MHPP test system. The renewables are used as a secondary energy source to provide the excitation current to a synchronous generator that generates energy in MHPP. A PV （photovoltaic） array is used as the main source of excitation, and a FC （fuel cell） stack is used for DC excitation in the lack of sunshine. In the experimental setup, an electrical control card is developed, and a microcontroller is used to perform the proposed excitation system. All experimental results obtained from 5 kW rated power MHHP test system. Experimental results show that, the proposed method provides the continuous excitation current, and the operation of the synchronous generator is uninterrupted. The proposed method is also practical and easily implemented for MHPP systems.

Four Years of Operating Experience with DryFiningTM Fuel Enhancement Process at Coal Creek Generating Station

Lignite and sub-bituminous coals from western U.S. contain high amounts of moisture （sub-bituminous： 15%-30%, lignites： 25%-40%）. German and Australian lignites （brown coals） have even higher moisture content, 50% and 60%, respectively. The high moisture content causes a reduction in plant performance and higher emissions, compared to the bituminous （hard） coals. Despite their high-moisture content, lignite and sub-bituminous coals from the western U.S. and worldwide are attractive due to their abundance, low cost, low NOx and SOx emissions, and high reactivity. A novel low-temperature coal drying process employing a fluidized bed dryer and waste heat was developed in the U.S. by a team led by GRE （Great River Energy）. Demonstration of the technology was conducted with the U.S. Department of Energy and GRE funding at Coal Creek Station Unit 1. Following the successful demonstration, the low-temperature coal drying technology was commercialized by GRE under the trade name DryFiningTM fuel enhancement process and implemented at both units at Coal Creek Station. The coal drying system at Coal Creek has been in a continuous commercial operation since December 2009. By implementing DryFining at Coal Creek, GRE avoided $366 million in capital expenditures, which would otherwise be needed to comply with emission regulations. Four years of operating experience is described in this paper.

Effects of Depression of Water Level in the Euphrates River in Iraq on the Operation of AI-Anbar Thermal Power Station

Increase in demand of electrical power for different purposes in Iraq leads increase towards to power plant system such as thermal power plant. Any thermal power plant requires water for processing, cooling, oilfields, boiler feed and other miscellaneous uses including domestic requirements. The main parameter to measure the efficiency of thermal power plant is the availability of water and technology employed. Therefore, the thermal power plants like A1-Anbar thermal power station is built on the Euphrates River bank in the city of Ramadi in the middle part of Iraq. Depending on the field measurements and pervious measurements, the computation of river water level for different frequency periods was achieved to determine the inundation area of the plant and the required height of power plant intakes. The problems of intake operation include low flow rate of the river at intake that resulting low water level （minimum flow rate was recorded 107 m^3/s with water level 47.8 m）, and annual sediments at intake that may be caused operation off. Therefore, any design for the intake or operation must consider the above problems. The study referred to the discharge for full operation is about 300 m^3/s and water level is 51.3 m to satisfy these requirements. The study suggested two solutions for this problem, first by using the groins and the second by building two weirs.

Excavation-induced microseismicity: microseismic monitoring and numerical simulation

The volume of influence of excavation at the right bank slope of Dagangshan Hydropower Station, southwest China, is essentially determined from microseismic monitoring, numerical modeling and conventional measurements as well as in situ observations. Microseismic monitoring is a new application technique for investigating microcrackings in rock slopes. A micro- seismic monitoring network has been systematically used to monitor rock masses unloading relaxation due to continuous exca- vation of rock slope and stress redistribution caused by dam impoundment later on, and to identify and delineate the potential slippage regions since May, 2010. An important database of seismic source locations is available. The analysis of microseismic events showed a particular tempo-spatial distribution. Seismic events predominantly occurred around the upstream slope of 1180 m elevation, especially focusing on the hanging wall of fault XL316-1. Such phenomenon was interpreted by numerical modeling using RFPA-SRM code （realistic failure process analysis-strength reduction method）. By comparing microseismic activity and results of numerical simulation with in site observation and conventional measurements results, a strong correlation can he obtained between seismic source locations and excavation-induced stress distribution in the working areas. The volume of influence of the rock slope is thus determined. Engineering practices show microseismic monitoring can accurately diagnose magnitude, intensity and associated tempo-spatial characteristics of tectonic activities such as faults and unloading zones. The integrated technique combining seismic monitoring with numerical modeling, as well as in site observation and conventional surveying, leads to a better understanding of the internal effect and relationship between microseismic activity and stress field in the right bank slope from different perspectives.

Applications of different criteria in structural damage identification based on natural frequency and static displacement

This paper presents a damage identification method that consists of a fusion sensitivity matrix that contains information on dynamic and static responses. Based on natural frequency and static displacement, the study defines and considers damage criteria such as 1D and 2D single and fusion load cases. To overcome the lack of sufficient information on damage identification in large-scale structures, the authors consider multiple responses to and objective descriptions of uncertainties and various criteria.According to the finite element model and the structural responses described and measured, the fusion methods and damage criteria treat uncertainty as non-probability intervals. As long as we know the bounds of uncertain parameters, the intervals of the elemental stiffness parameters in undamaged and damaged models can be obtained by interval technology. Two numerical examples—a damage-criteria numerical example and a 5-span with 25-bar truss structure in a space solar power station—are proposed. Both examples indicate the veracity of the interval method.

GREEN POWER, GREEN DEVELOPMENT

The Wudongde Hydropower Station aims to power economic growth A bright new era for hydropower stations was ushered in when Laurent Fabius,Chairman of the UN Climate Change Conference in Paris and also the French Foreign Minister,brought down his gavel,announcingthe birth of the Paris Agreement on Climate Change on December 12, 2015.