This paper describes the present situation, construction experiences, existing problems and the principal tasks in the development of small hydropower in China.
With suitable assumptions a hydrodynamic model for the magnetic fluid motion in an axial variable gap seal was con- structed, and the solution to the equations of the model was deduced. The characteristics of a magnet...With suitable assumptions a hydrodynamic model for the magnetic fluid motion in an axial variable gap seal was con- structed, and the solution to the equations of the model was deduced. The characteristics of a magnetic fluid seal and its motion, including the speed and pressure distribution, and the seal capacity of a magnetic fluid rotating seal were systematically described. The factors affecting seal capacity and ways to improve seal capacity based on the hydrodynamic model are discussed. The basic condition for dynamic seal availability is presented. The rotating speed and radius of the shafts should be decreased. The work can provide proof of a seal design or suggest ways to improve the seal capacity of magnetic fluid seals.展开更多
Long-term kinematic research of slow- moving debris slide is rare despite of the widespread global distribution of this kind. This paper presents a study of the kinematics and mechanism of the Jinpingzi debris slide l...Long-term kinematic research of slow- moving debris slide is rare despite of the widespread global distribution of this kind. This paper presents a study of the kinematics and mechanism of the Jinpingzi debris slide located on the Jinsha river bank in southwest China. This debris slide is known to have a volume of 27×106 ms in active state for at least one century. Field survey and geotechnical investigation were carried out to define the structure of the landslide. The physical and mechanical properties of the landslide materials were obtained by in-situ and laboratory tests. Additionally, surface and subsurface displacements, as well as groundwater level fluctuations, were monitored since 2005. Movement features, especially the response of the landslide movement to rainfall, were analysed. Relationships between resisting forces and driving forces were analysed by using the limit equilibrium method assuming rigid-plastic frictional slip. The results confirmed a viscous comoonent in the long-term continuous movement resulting in the quasioverconsolidated state of the slip zone with higher strength parameters than some other types of slowmoving landslides. Both surface and subsurface displacements showed an advancing pattern by the straight outwardly inclined (rather than gently or reversely inclined) slip zone, which resulted in low resistance to the entire sliding mass. The average surface displacement rate from 2005 to 2016 was estimated to be 0.19-0.87 mm/d. Basal sliding on the silty clay seam accounted for most of the deformation with different degrees of internal deformation in different parts. Rainfall was the predominant factor affecting the kinematics of Jinpingzi landslide while the role of groundwater level, though positive, was not significant. The response of the groundwater level to rainfall infiltration was not apparent. Unlike some shallow slow-moving earth flows or mudslides, whose behaviors are directly related to the phreatic groundwater level, the mechanism for Jinpingzi landslide kinematics is more likely related to the changing weight of the sliding mass and the downslope seepage pressure in the shallow soil mass resulting from rainfall events.展开更多
This paper establishes a 3D numerical model for 15# hydropower house of the Three Gorges Project (TGP) and performs a nonlinear static and dynamic damage analysis. In this numerical model, a coupling model of finite a...This paper establishes a 3D numerical model for 15# hydropower house of the Three Gorges Project (TGP) and performs a nonlinear static and dynamic damage analysis. In this numerical model, a coupling model of finite and infinite elements for simulating infinite foundation of hydropower station is adopted. A plastic-damage model based on continuum damage mechanics, which includes the softening and damage behavior under tension is considered for the concrete material. The dynamic equilibrium equations of moti...展开更多
Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to com...Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation.展开更多
Pyropia yezoensis, belongs to the genus of P orphyra before 2011, inhabit on intertidal zone rocks where irradiation changes dramatically, implying that the seaweed has gained certain mechanisms to survive a harsh env...Pyropia yezoensis, belongs to the genus of P orphyra before 2011, inhabit on intertidal zone rocks where irradiation changes dramatically, implying that the seaweed has gained certain mechanisms to survive a harsh environment. Based on the photosynthetic parameters with or without the inhibitors determined by a Dual-PAM-100 apparatus, we investigated the photosynthetic performance and the changes in electron fl ow that occurred during the algae were stressed with dif ferent light intensities previously. When the irradiation saturation was approaching, the CEF around PS I became crucial since the addition of inhibitors usually led to an increase in non-photochemical quenching. The inhibitor experiments showed that there were at least three dif ferent CEF pathways in Py. yezoensis and these pathways compensated each other. In addition to maintaining a proper ratio of ATP/NAD(P)H to support effi cient photosynthesis, the potential roles of CEF might also include the regulation of dif ferent photoprotective mechanisms in Py. yezoensis. Under the regulation of CEF, chlororespiration is thought to transport electrons from the reduced plastoquinone(PQ) pool to oxygen in order to mitigate the reduction in the electron transfer chain. When irradiation was up to the high-grade stress conditions, the relative value of CEF began to decrease, which implied that the NADP+ pool or PQ + pool was very small and that the electrons were transferred from reduced PS I to oxygen. The scavenging enzymes might be activated and the water-water cycle probably became an ef fective means of removing the active oxygen produced by the irradiation stressed Py. yezoensis. We believe that the dif ferent mechanisms could make up the photoprotective network to allow Py. yezoensis for survival in a highly variable light stress habitat, which may enlighten scientists in future studies on irradiance stress in other algae species.展开更多
The research object was high 120 m concrete gravity dam of the Angara Bratsk hydroelectric power plant. The state of the concrete dam is estimated based on the results of continuous supervision performed by site perso...The research object was high 120 m concrete gravity dam of the Angara Bratsk hydroelectric power plant. The state of the concrete dam is estimated based on the results of continuous supervision performed by site personnel as well as periodic monitoring. According to the classification of the interrelations in the system "concrete-environment", there were selected some important parts of dams and a comprehensive analysis of concrete was executed on these parts. Concerning the complex research of concrete, a combination of full-scale tests with core-sampling has been proposed. Core samples tests had an object to study the deep concrete layers and to determine the specific indicators such as strength, density, porosity, comparative diameter of capillary pores, CaO content in cement stone and others. Obtained findings and recommended criteria can be applied when selecting technologies for constructing dams that guarantee their durability in the north.展开更多
This research study was conducted to review the environmental and social impact of mini hydropower plants (run-of-the-river type) by selecting Denawaka Ganga mini hydropower plant, which is located in Ratnapura dist...This research study was conducted to review the environmental and social impact of mini hydropower plants (run-of-the-river type) by selecting Denawaka Ganga mini hydropower plant, which is located in Ratnapura district, Sri Lanka. Field visits and discussions among the authors, authorities and the residents were carried out. Then, the environmental and social impacts were scientifically analysed using regulation degree (RD) and environmental impact value (EIV) scores. It was found out that the Denawaka Ganga mini hydropower plant has induced some environmental concerns; however, significant positive social impact to the society. This is in addition to the green energy generation. Therefore, it can be concluded herein that the Denawaka Ganga mini hydropower is an asset to the country, Sri Lanka.展开更多
In terms of hydropower resources in the country, Nepal ranks second in the world. But it has not acted seriously in terms of utilization. The effort began from the Rana days when they ruled the country for more than c...In terms of hydropower resources in the country, Nepal ranks second in the world. But it has not acted seriously in terms of utilization. The effort began from the Rana days when they ruled the country for more than century. For energy, unfortunately, the country has at times sought thermal source rather than hydropower.For energy needs, it first depended upon foreign aid in the earlier dates. As late as in the '60s, it depended upon such assistance rather than developing its own. So much so, that it imported electrical power from neighbouring country. Later, it was developed both under foreign aid as well the multilateral assistance and loan. The electricity generation gradually became more and more costly. Only later, genuine private sectors have joined the energy market. But the terms and conditions have not always been in the national interest. There is a wide variation in cost of energy under different conditions of power development in the country, from the cheapest to the costliest. Both for generation and distribution, Nepal Electric Corporation should no longer continue its monopoly.Private sector should be promoted given more role to play for economy and operation.The paper discusses the different options available and practised in Nepal.展开更多
This paper presents the modelling, simulation and analysis of the dynamic behaviour of a mixed power network of 2.78 GW including hydro, thermal and wind power plants. The modelling of each power plant is described. T...This paper presents the modelling, simulation and analysis of the dynamic behaviour of a mixed power network of 2.78 GW including hydro, thermal and wind power plants. The modelling of each power plant is described. The set of parameters of the turbine speed governor of the hydroelectric power plant is determined with a specific identification procedure to achieve stable operation for different cases such as interconnected, isolated or islanded operation. The analysis of the stability of the entire mixed islanded power plant is investigated through time domain simulations for different sets of controllers parameters and for different disturbances (load rejection and turbulent wind speed profile).展开更多
The main objective of this study was to determine the consolidation behaviour of clay slurries.A finegrained clay with high consistency limits(W_L = 180%,w_P= 120%) was investigated using conventional oedometer and be...The main objective of this study was to determine the consolidation behaviour of clay slurries.A finegrained clay with high consistency limits(W_L = 180%,w_P= 120%) was investigated using conventional oedometer and bench-top centrifuge tests.Results indicated that the slurry had an apparent preconsolidation(due to initial conditions,electrochemical interactions,tortuous drainage,and thixotropic strength) from e = 5.7 to e = 5.5 followed by virgin compression.Likewise,the low hydraulic conductivity(10^(-10)-10^(-12) m/s) was due to low porosity(small pore throats) and high tortuosity(long flow paths).Unlike consolidation of soils,the c_v and m_v decreased with increasing σ' but increased with increasing e and k.The data from the two tests correlated well in the range of σ' = 10-65 kPa,e = 5.5-3.86,k= 1.7 × 10^(-10)-5×10^(-11) m/s,F_c = 1-40 MN.New equations were developed to correlate the consolidation parameters(e,σ',k) with F_c.The deviation of k beyond 40 MN(e = 4.65) was due to deviation from the initial straight line portion of the settlement curve in the centrifuge test.展开更多
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 a...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.展开更多
Excitation system is one of the significant elements affecting the dynamic performance of electric power systems. The power engineering as area of science and industry is subjected to rapid modernization, which is cau...Excitation system is one of the significant elements affecting the dynamic performance of electric power systems. The power engineering as area of science and industry is subjected to rapid modernization, which is caused by technological progress. However, not all elements of the power system are developing simultaneously. The old type of elements sometimes is sufficient to adapt old system to the new operational conditions. The work developed and proposed in this paper deals with analysis of possible optimization of synchronous generator's excitation system. Authors examined influence of excitation system's parameters to the dynamics of transient processes in the power system. Authors investigated optimal parameters of excitation system of the Kegums hydro power plant. For optimization of parameters objective functions were used. The problem of the mutual influence of excitation systems of neighbor power plants was investigated. Investigation of transient processes using developed model proved that optimization of excitation parameters improves efficiency of regulation of excitation system, damping of active power oscillation and in some cases can prevent out-of-step condition.展开更多
This paper focuses on the state space modeling approach and output torques prediction of torsional vibrations for variable speed wind turbines. The multi-body system model under study is mainly comprised of a wind tur...This paper focuses on the state space modeling approach and output torques prediction of torsional vibrations for variable speed wind turbines. The multi-body system model under study is mainly comprised of a wind turbine, a three stage planetary gear box and an induction generator. The masses-springs approach of shaft system differential equations is developed from Newton's law and Lagrange formulas. For an easy comprehension for electrical engineers and tutorial purpose, an electrical equivalent circuit of the system is proposed by using mechanical and electrical components similarities. Extensive numerical simulations are performed to investigate system mechanical resonances and impacts of damping factors on the system dynamic and stability.展开更多
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...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.展开更多
As a main constituent of geological body, the rock masses have distinct differences from other materials, one of which is that rock masses are initially stressed in their natural states. Hence, it is an extremely chal...As a main constituent of geological body, the rock masses have distinct differences from other materials, one of which is that rock masses are initially stressed in their natural states. Hence, it is an extremely challenging and significant research project to know the present residual stress of the rock masses in the earth's crust. Although some regularities of distribution of in-situ rock stresses can be deduced, the basic means to study the state of rock stress is in-situ stress measurement. After a brief review of several measuring methods of in-situ 3D rock stress, a new one, borehole wall stress relief method (BWSRM) to determine the in-situ 3D rock stress tensor in a single drilled borehole was proposed. Based on the principle of in-situ rock stress measurement with BWSRM, an original geostress measuring instrument was designed and manufactured. Preliminary experiments for determination of in-situ stress orientation and magnitude were carried out at an experimental tunnel in Jinping Ⅱ hydropower station in China, where the buried depth of overburden was about 2430 m. The results showed that it was feasible to measure the in-situ 3D rock stresses with BWSRM presented in this paper. The BWSRM has a broad prospect for in-situ 3D rock stress measurements in practical rock engineering.展开更多
文摘This paper describes the present situation, construction experiences, existing problems and the principal tasks in the development of small hydropower in China.
基金Project 59975083 supported by the National Natural Science Foundation of China
文摘With suitable assumptions a hydrodynamic model for the magnetic fluid motion in an axial variable gap seal was con- structed, and the solution to the equations of the model was deduced. The characteristics of a magnetic fluid seal and its motion, including the speed and pressure distribution, and the seal capacity of a magnetic fluid rotating seal were systematically described. The factors affecting seal capacity and ways to improve seal capacity based on the hydrodynamic model are discussed. The basic condition for dynamic seal availability is presented. The rotating speed and radius of the shafts should be decreased. The work can provide proof of a seal design or suggest ways to improve the seal capacity of magnetic fluid seals.
文摘Long-term kinematic research of slow- moving debris slide is rare despite of the widespread global distribution of this kind. This paper presents a study of the kinematics and mechanism of the Jinpingzi debris slide located on the Jinsha river bank in southwest China. This debris slide is known to have a volume of 27×106 ms in active state for at least one century. Field survey and geotechnical investigation were carried out to define the structure of the landslide. The physical and mechanical properties of the landslide materials were obtained by in-situ and laboratory tests. Additionally, surface and subsurface displacements, as well as groundwater level fluctuations, were monitored since 2005. Movement features, especially the response of the landslide movement to rainfall, were analysed. Relationships between resisting forces and driving forces were analysed by using the limit equilibrium method assuming rigid-plastic frictional slip. The results confirmed a viscous comoonent in the long-term continuous movement resulting in the quasioverconsolidated state of the slip zone with higher strength parameters than some other types of slowmoving landslides. Both surface and subsurface displacements showed an advancing pattern by the straight outwardly inclined (rather than gently or reversely inclined) slip zone, which resulted in low resistance to the entire sliding mass. The average surface displacement rate from 2005 to 2016 was estimated to be 0.19-0.87 mm/d. Basal sliding on the silty clay seam accounted for most of the deformation with different degrees of internal deformation in different parts. Rainfall was the predominant factor affecting the kinematics of Jinpingzi landslide while the role of groundwater level, though positive, was not significant. The response of the groundwater level to rainfall infiltration was not apparent. Unlike some shallow slow-moving earth flows or mudslides, whose behaviors are directly related to the phreatic groundwater level, the mechanism for Jinpingzi landslide kinematics is more likely related to the changing weight of the sliding mass and the downslope seepage pressure in the shallow soil mass resulting from rainfall events.
基金Supported by National Natural Science Foundation of China (No.50679009)Key Laboratory for Scientific Research of Department of Education in Liaoning Province (No.2008S045)
文摘This paper establishes a 3D numerical model for 15# hydropower house of the Three Gorges Project (TGP) and performs a nonlinear static and dynamic damage analysis. In this numerical model, a coupling model of finite and infinite elements for simulating infinite foundation of hydropower station is adopted. A plastic-damage model based on continuum damage mechanics, which includes the softening and damage behavior under tension is considered for the concrete material. The dynamic equilibrium equations of moti...
基金Chinese Academy of Science (No.KGCX2- YW- 366)Ministry of Science and Technology(No. 2011AA05A106)
文摘Small-hydro power station is often used in remote areas beside a river,but it doesn't match electricity demand so well,especially in dry seasons. A photovoltaic (PV) system with battery is a suitable option to complement the electricity gap. In this paper,a new structure of megawatt-class PV system integrating battery at DC-bus (DC: direct current) is proposed to be used in hydro/PV hybrid power system,and 4 main designing considerations and several key equipments are discussed. In 2011,a 2 MWp PV station with the proposed structure was built up in Yushu,China. From stability analysis,the station shows a strong stability under load cut-in/off and solar irradiance's fluctuation.
基金Supported by the National Natural Science Foundation of China(No.41176134)the Laboratory for Marine Biology and Biotechnology,Qingdao National Laboratory for Marine Science and Technology,the Prospective Joint Research Project of Jiangsu Province(No.BY2011188)+1 种基金the National Basic Research Program of China(973 Program)(No.2011CB411908)the National Marine Public Welfare Research Project(Nos.201105023-8,201105008-2)
文摘Pyropia yezoensis, belongs to the genus of P orphyra before 2011, inhabit on intertidal zone rocks where irradiation changes dramatically, implying that the seaweed has gained certain mechanisms to survive a harsh environment. Based on the photosynthetic parameters with or without the inhibitors determined by a Dual-PAM-100 apparatus, we investigated the photosynthetic performance and the changes in electron fl ow that occurred during the algae were stressed with dif ferent light intensities previously. When the irradiation saturation was approaching, the CEF around PS I became crucial since the addition of inhibitors usually led to an increase in non-photochemical quenching. The inhibitor experiments showed that there were at least three dif ferent CEF pathways in Py. yezoensis and these pathways compensated each other. In addition to maintaining a proper ratio of ATP/NAD(P)H to support effi cient photosynthesis, the potential roles of CEF might also include the regulation of dif ferent photoprotective mechanisms in Py. yezoensis. Under the regulation of CEF, chlororespiration is thought to transport electrons from the reduced plastoquinone(PQ) pool to oxygen in order to mitigate the reduction in the electron transfer chain. When irradiation was up to the high-grade stress conditions, the relative value of CEF began to decrease, which implied that the NADP+ pool or PQ + pool was very small and that the electrons were transferred from reduced PS I to oxygen. The scavenging enzymes might be activated and the water-water cycle probably became an ef fective means of removing the active oxygen produced by the irradiation stressed Py. yezoensis. We believe that the dif ferent mechanisms could make up the photoprotective network to allow Py. yezoensis for survival in a highly variable light stress habitat, which may enlighten scientists in future studies on irradiance stress in other algae species.
文摘The research object was high 120 m concrete gravity dam of the Angara Bratsk hydroelectric power plant. The state of the concrete dam is estimated based on the results of continuous supervision performed by site personnel as well as periodic monitoring. According to the classification of the interrelations in the system "concrete-environment", there were selected some important parts of dams and a comprehensive analysis of concrete was executed on these parts. Concerning the complex research of concrete, a combination of full-scale tests with core-sampling has been proposed. Core samples tests had an object to study the deep concrete layers and to determine the specific indicators such as strength, density, porosity, comparative diameter of capillary pores, CaO content in cement stone and others. Obtained findings and recommended criteria can be applied when selecting technologies for constructing dams that guarantee their durability in the north.
文摘This research study was conducted to review the environmental and social impact of mini hydropower plants (run-of-the-river type) by selecting Denawaka Ganga mini hydropower plant, which is located in Ratnapura district, Sri Lanka. Field visits and discussions among the authors, authorities and the residents were carried out. Then, the environmental and social impacts were scientifically analysed using regulation degree (RD) and environmental impact value (EIV) scores. It was found out that the Denawaka Ganga mini hydropower plant has induced some environmental concerns; however, significant positive social impact to the society. This is in addition to the green energy generation. Therefore, it can be concluded herein that the Denawaka Ganga mini hydropower is an asset to the country, Sri Lanka.
文摘In terms of hydropower resources in the country, Nepal ranks second in the world. But it has not acted seriously in terms of utilization. The effort began from the Rana days when they ruled the country for more than century. For energy, unfortunately, the country has at times sought thermal source rather than hydropower.For energy needs, it first depended upon foreign aid in the earlier dates. As late as in the '60s, it depended upon such assistance rather than developing its own. So much so, that it imported electrical power from neighbouring country. Later, it was developed both under foreign aid as well the multilateral assistance and loan. The electricity generation gradually became more and more costly. Only later, genuine private sectors have joined the energy market. But the terms and conditions have not always been in the national interest. There is a wide variation in cost of energy under different conditions of power development in the country, from the cheapest to the costliest. Both for generation and distribution, Nepal Electric Corporation should no longer continue its monopoly.Private sector should be promoted given more role to play for economy and operation.The paper discusses the different options available and practised in Nepal.
文摘This paper presents the modelling, simulation and analysis of the dynamic behaviour of a mixed power network of 2.78 GW including hydro, thermal and wind power plants. The modelling of each power plant is described. The set of parameters of the turbine speed governor of the hydroelectric power plant is determined with a specific identification procedure to achieve stable operation for different cases such as interconnected, isolated or islanded operation. The analysis of the stability of the entire mixed islanded power plant is investigated through time domain simulations for different sets of controllers parameters and for different disturbances (load rejection and turbulent wind speed profile).
基金the University of Regina for providing laboratory space and the Natural Science and Engineering Research Council of Canada for financial assistance
文摘The main objective of this study was to determine the consolidation behaviour of clay slurries.A finegrained clay with high consistency limits(W_L = 180%,w_P= 120%) was investigated using conventional oedometer and bench-top centrifuge tests.Results indicated that the slurry had an apparent preconsolidation(due to initial conditions,electrochemical interactions,tortuous drainage,and thixotropic strength) from e = 5.7 to e = 5.5 followed by virgin compression.Likewise,the low hydraulic conductivity(10^(-10)-10^(-12) m/s) was due to low porosity(small pore throats) and high tortuosity(long flow paths).Unlike consolidation of soils,the c_v and m_v decreased with increasing σ' but increased with increasing e and k.The data from the two tests correlated well in the range of σ' = 10-65 kPa,e = 5.5-3.86,k= 1.7 × 10^(-10)-5×10^(-11) m/s,F_c = 1-40 MN.New equations were developed to correlate the consolidation parameters(e,σ',k) with F_c.The deviation of k beyond 40 MN(e = 4.65) was due to deviation from the initial straight line portion of the settlement curve in the centrifuge test.
文摘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.
文摘Excitation system is one of the significant elements affecting the dynamic performance of electric power systems. The power engineering as area of science and industry is subjected to rapid modernization, which is caused by technological progress. However, not all elements of the power system are developing simultaneously. The old type of elements sometimes is sufficient to adapt old system to the new operational conditions. The work developed and proposed in this paper deals with analysis of possible optimization of synchronous generator's excitation system. Authors examined influence of excitation system's parameters to the dynamics of transient processes in the power system. Authors investigated optimal parameters of excitation system of the Kegums hydro power plant. For optimization of parameters objective functions were used. The problem of the mutual influence of excitation systems of neighbor power plants was investigated. Investigation of transient processes using developed model proved that optimization of excitation parameters improves efficiency of regulation of excitation system, damping of active power oscillation and in some cases can prevent out-of-step condition.
文摘This paper focuses on the state space modeling approach and output torques prediction of torsional vibrations for variable speed wind turbines. The multi-body system model under study is mainly comprised of a wind turbine, a three stage planetary gear box and an induction generator. The masses-springs approach of shaft system differential equations is developed from Newton's law and Lagrange formulas. For an easy comprehension for electrical engineers and tutorial purpose, an electrical equivalent circuit of the system is proposed by using mechanical and electrical components similarities. Extensive numerical simulations are performed to investigate system mechanical resonances and impacts of damping factors on the system dynamic and stability.
基金supported by the National Natural Science Foundation of China (Nos. 50820125405, 50909013 and 50804006)the National Basic Research Program (973) of China (No. 2007CB209404)
文摘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.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50579037, 50639080, 50979054)the Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering (Grant No. SKLZ0901)
文摘As a main constituent of geological body, the rock masses have distinct differences from other materials, one of which is that rock masses are initially stressed in their natural states. Hence, it is an extremely challenging and significant research project to know the present residual stress of the rock masses in the earth's crust. Although some regularities of distribution of in-situ rock stresses can be deduced, the basic means to study the state of rock stress is in-situ stress measurement. After a brief review of several measuring methods of in-situ 3D rock stress, a new one, borehole wall stress relief method (BWSRM) to determine the in-situ 3D rock stress tensor in a single drilled borehole was proposed. Based on the principle of in-situ rock stress measurement with BWSRM, an original geostress measuring instrument was designed and manufactured. Preliminary experiments for determination of in-situ stress orientation and magnitude were carried out at an experimental tunnel in Jinping Ⅱ hydropower station in China, where the buried depth of overburden was about 2430 m. The results showed that it was feasible to measure the in-situ 3D rock stresses with BWSRM presented in this paper. The BWSRM has a broad prospect for in-situ 3D rock stress measurements in practical rock engineering.