Water-wheel Generators Research Articles

Micro-hydropower systems for smallholder farmers in rural communities of Taraba state, Nigeria: Socioeconomic assessment of needs and perceptions (Part I)

The Nigerian government’s recent initiative, “Electrifying Agriculture,” supports the rapid deployment of off-grid electricity solutions to transform food systems. Agriculture is the primary source of income for Taraba State residents. In rural communities, success of potential climate-smart agriculture interventions requires participation and acceptance of the community. This research article evaluates the socioeconomic needs and perception of hydropower solutions for three rural communities in Taraba State, Nigeria. The findings reveal a higher proportion of males (72.22%) than females, with majority (53.17%) of them having no formal education. Social facilities and services like roads, education and health institutions, water, electricity and communication, and public recreation facilities are generally available but poorly maintained. The majority of inhabitants depend on nearby rivers and commercial boreholes as major sources of water for domestic purposes, with 65.87% of the residents throwing solid wastes into the bush. Also, the major (98.41%) source of energy or fuel for cooking is firewood. On the basis of priority, the three most relevant personal and community needs identified for interventions are the provision of low-cost off-grid electricity (95.83%); primary health care clinics (84.13%) and farming inputs (83.33%), among others. A majority (90.48%) of the respondents agreed that installation of low-cost, off-grid water wheel generators will serve as an alternative to solve Taraba state’s energy challenges, ensure energy security and improve the economy, while 93.65% of them are willing to sustain off-grid water wheel generator in their communities if they are installed. The results further indicate that provision of security and surveillance to prevent stealing and vandalism using community vigilante (57.81%) is a viable way of sustaining the investment, even as a majority (77.22%) of them agreed that corruption is a challenge that can affect the sustainability of off-grid water wheel generators in the communities if not addressed.

시화호 조력발전소 신설에 따른 전력계통 특성 및 경제적 이득 분석

This paper presents the various analysis of the power system for operating the new SIHWA tidal power plant. In the analysis of the power system, summer load condition of 2011 is used. Especially, power flow, fault current, voltage and contingency of SIHWA tidal power plant area are analyzed by using PSS/E and there is no problem for the dynamic stability simulation. The new SIHWA tidal power plant is located in near metropolitan area where about 43% amount of the system load is consumed. Therefore, transmission losses are reduced. In addition, system marginal price can be lowered by generating the new SIHWA tidal power plant. The generation pattern of the SIHWA tidal plant is analyzed and the changes of generation are presented for various water levels by control of the rotor angle alpha and beta in water wheel generator.

Corona in high voltage rotating machine windings

An understanding is provided of the phenomena that take place in the windings of turbine generators, water wheel generators, and large motors. The steps that are normally taken by a manufacturer to alleviate this type of electrical aging are reviewed. >

Simulation of the Steady-State Reactances of a Large Water-Wheel Generator by Finite Elements

Finite elements have been widely used for the prediction of turbogenerators steady-state reactances. In comparison, water-wheel generators have received little attention in the literature. The present paper, while explaining the difficulties associated with the analysis of salient pole machines, describes a new method for the prediction of the steady-state reactances of a hydrogenerator. The method is applied to a large water-wheel generator and the computed reactances are compared with those obtained from the manufacturer's shop-floor tests.

Simulation of the Steady-State Reactances of a Large Water-Wheel Generator by Finite Elements

Simulation of the Steady-State Reactances of a Large Water-Wheel Generator by Finite Elements

Simulation of the Transient and Subtransient Reactances of a Large Hydrogenerator by Finite Elements

This paper describes a method for the computation of the transient and subtransient reactances of synchronous machines by finite elements. It employs the concept that boundary conditions may be used to isolate different regions of the problem domain. By using this approach, the regions of the problem domain which contain induced currents in the transient and subtransient regimes, are isolated. Great simplification of the problem is gained as a result of this practice. The method is implemented on a large water-wheel generator with first order nonlinear triangular elements. Extreme load levels as well as armature flux angles have been examined. The computational results in all the cases studied show a good accordance with the manufacturer's shop-floor tests.

Principles of a Water-Wheel Generator with Floating Rotor

Principles of a Water-Wheel Generator with Floating Rotor

Principles of a Water-Wheel Generator with Floating Rotor

In an axial-field vertical-shaft hydro-electric generator, magnetic pull can be utilized to support the rotating body and provide smooth starting and stopping. The magnetic flux densities in the generator's upper and lower airgaps are purposely made unequal by injecting unequal currents in its two field windings. In addition to other advantageous features which also justify the axial-field configuration, the floating rotor principle greatly simplifies the construction of the thrust bearing and its auxiliary mechanical system. Operations of turbine-generator sets will no longer be restricted by their bearing temperature as they are now with conventional units. An experimental machine was designed, constructed and tested.

The use of finite elements in the simulation of the steady state operation of a synchronous generator with a known terminal loading condition

A direct finite element method for the simulation of the steady state load operating point of a synchronous generator is introduced. The terminal constraints of the generator under load are conveniently expressed in terms of the system state vector. This makes it possible to solve the finite element equations along with the terminal constraints in a single run, hence avoiding unnecessary iterations. The method presented is applicable to both turbo- and waterwheel generators in so far as saliency is concerned. However, since a two dimensional analysis has been adopted, it is expected that the prominent end region effect will be more noticeable in short stack hydro units.

Damping of Power Oscillations in Salient-Pole Machines with Static Exciters

It is generally accepted that a high-performance excitation system may reduce the effective internal damping of a synchronous machine. Alternately, studies and field tests indicate that a fast-acting excitation system offers the best opportunity for increased damping through the use of an auxiliary signal into the voltage regulator. The application of static exciters to water-wheel generators requires an awareness of these possible changes in machine damping. The use of an auxiliary damping signal into the voltage regulator may become especially important for machines that are inherently lightly damped.

Norwegian Experience with Electrical Insulation for Large Rotating Machinery

This paper deals with the stator winding insulation primarily of water-wheel generators and experience in Norway with this important part of rotating machines. Until 1962, first shellac, and later asphalt bonded micafolium were used as ground insulation of high-voltage machines. In 1962, a new insulation system based on a mica-splitting tape with modified polyester resin as impregnant was introduced. The advantages of this new system include high mechanical strength at elevated temperatures and superior thermal endurance characteristics. The system also has proved to be practically noninflammable, which could justify omission of the automatic fire-extinguishing equipment normally used nowadays to protect generators against fire. In spite of higher material costs, the overall price of the new system compares favorably with the old systems. The reason for this is that the new system has only a few different materials, the materials are easy to handle, and the production process is simple and easy to control. The new insulation system is being used today in Norway for all machine ratings above 500 kVA and all voltages above 3 kV.

Investigation of Maintenance Tests for Generator Insulation

A large water-wheel generator winding, about to be replaced, was subjected to all available tests. When the winding had cooled in air of summer humidity, nondestructive indications of d-c strength were readily obtained and were proved, by subsequent deliberate breakdowns, to be near enough to actual breakdown strength for practical judgment of condition. This had not been found possible with dry windings. After repeated and protracted exposure to direct voltages near breakdown, no damaging effects could be discerned by d-c leakage, 60-cycle power factor (pf), or physical dissection. Under high direct voltage, artificial breakdowns were applied; resulting surge voltages were measured and found to be harmless. Power-factor-voltage tests, slot-discharge tests, and corona tests were correlated with physical conditions found on dissecting coils. Phase-to-ground impulse measurements showed a relationship between oscillation frequency and fault location. Turn-to-turn impulse tests showed definite fault detection, but could be made on only one coil at a time. One incipient turn-toturn fault was located in situ by an ionization probe, but the method used was shown to need improved discrimination. Through the collaboration of various authorities in this series of tests, greater appreciation of the potentialities and limitations of the methods was obtained.

An Unusual Method Ror Replacing a Rotor Spider in a Water-Wheel Generator

Ultrasonic tests made following the discovery of cracks in the hub of a caststeel rotor spider of a 15,000-kva waterwheel generator indicated the advisability of replacing the spider with one of modern fabricated steel design. Economic considerations favored making the replacement without disturbing the field poles and laminated rim. A special jacking rig was devised with which the spider was pressed out of the rim in approximately 90 working hours. Removal of the old spider and installation of the new spider was accomplished in 34 shifts and required 2,570 man-hours. Estimated savings of 48.5% in time and 43.6% in labor were made by performing the work in this manner rather than by the conventional method of removing field poles, unstacking the laminated rim from the old spider, restacking the laminations on the new spider, and reinstalling the field poles.

A Utility's Functional Evaluation Tests for High-Voltage Stator Insulation

This is a progress report on research projects conducted in co-operation with the AIEE Rotating Machinery Insulation Subcommittee, the Canadian Electrical Association's Apparatus Section, and individual manufacturers and utilities. For the functional evaluation required by a utility, a voltage-endurance test was chosen as most indicative of the ionization resistance which is considered critical in short-bore water-wheel generators, and a test of endurance of the mechanical effects of thermal cycling was chosen as most applicable to the critical qualities of insulation for steamturbine generators and other long-bore machines. Test equipments of moderate size and cost have been developed for voltage and mechanical endurance. Emphasis has been laid on close control of aging influences; variation of voltage test lives of similar samples has been reduced to within a ratio of three to one. The voltage-endurance equipment is finding further use in studies of effects upon insulation life of various dry-out, overvoltage testing, and operating practices. The mechanical-endurance tester is being used in a study of the optimum clearances between coil side and slot for various insulations.

Evolution of large thrust bearing design

VERTICAL WATER WHEEL generator units have been made possible, to a large extent, by the development of efficient and reliable thrust bearings.

Oil Seals to Provide Positive Lubrication on Large or High-Speed Thrust Bearings

Abstract Vertical waterwheel generators are provided with large thrust bearings the surfaces of which are separated by a hydrodynamic oil film. In order to insure the formation of the required oil film, a continuous and sufficient supply of oil is required. With thrust bearings of increased size or speed, aeration of the oil may cause inadequate lubrication of the bearing surfaces or result in oil leakage. This paper discusses the application of positive oil seals which effectively prevent aeration of the oil and oil leakage.

Influence of Load and Thermal Distortion on the Design of Large Thrust Bearings

Abstract High-capacity vertical waterwheel generators require large thrust bearings in which the load is carried on a thin hydrodynamic film of oil. Thermal and load distortion of the bearing parts have to be limited to a low value to permit the normal and complete formation of the oil film predicted by the hydrodynamic theory of lubrication. Excessive load and thermal distortion materially affect bearing performance and may result in bearing failure. This paper describes some design considerations given to vertical waterwheel-generator thrust bearings in order to avoid highly concentrated loading during the starting period, and to obtain minimum distortion of the pad during operation at normal speed and load.

The Evolution of the Modern Waterwheel Generator in Canada

This paper deals with characteristics of utility loads in Canada, and the characteristics required in generators to match them; with some examples of means that have been employed for this purpose.

Late Discussions [Discussion of "The evolution of the modern waterwheel generator in Canada", Paper 57-689

Late Discussions [Discussion of "The evolution of the modern waterwheel generator in Canada", Paper 57-689

Some Mechanical Considerations in the Design of Large Thrust Bearings

The modern thrust bearing is a very important part of the waterwheel generator, for it must support the weight of the rotating parts of the turbine and generator and the hydraulic thrust load. With the continuous increase in size of hydroelectric generating units, machines now are built with thrust loads well above 1000 tons and requiring bearings ten feet in diameter or larger. Continuous trouble-free operation for periods of twenty years or more are desired for the bearings of large hydroelectric units. Except during the starting period, the pivoted pad thrust bearing operates according to the well-known hydrodynamic theory of lubrication which permits the predetermination of its performance with reasonable accuracy. Alternating slipping between the thrust bearing runner and the supporting structure can result in excessive wear which destroy the accuracy of the bearing surfaces. Such wear can cause undesirable vibrations or damage to the bearing surface which prevents the formation of an adequate oil fi...