Hydraulic Generator Research Articles

Computational analysis of vortex rope in a hydroturbine of Tucuruí dam

There is a relevant hydraulic potential in Amazon rivers, from which it is generated most of the energy available for the largest part of Brazil. One of the most important hydropower plants in the Amazon is Tucurui dam, which can produce 8370 MW through Francis turbines. This kind of turbine often presents hydrodynamic issues due to the vortex rope formation, which can induce vibrations and reduce assembly operating life. The present work concentrates in a computational study to determine the frequency pressure fluctuations in a hydraulic generation unit of the Tucurui hydroelectric power plant. A numerical technique is applied for modeling the turbulent flow throughout the generation unit in a transient regime using finite volume method. For the analysis of velocity and pressure fields on the hydrogenerator, a 3D fully turbulent transient modeling for characterizing the pressure fluctuations at the runner outlet is performed. The structure of vortex rope formed is investigated in order to evaluate the hydrodynamic phenomena resulting from the turbine operating condition. Low-frequency pressure pulsations are caused by the movement of the vortex rope at the runner outlet. Additionally, vortex shedding dynamics is heavily influenced by the turbine operating conditions, demonstrating the importance of such investigation. For 63% distributor opening, the structure of the vortex rope reaches a big size in the suction duct, increasing the possibility of vibration. For 89% distributor opening, the turbine operates under overload condition, and the vortex rope becomes unstable. Comparisons with field data show the efficiency and validity of the numerical modeling, demonstrating good agreement.

A Reservoir Operation Policy Using Inter-Basin Water Transfer for Maximizing Hydroelectric Benefits in Brazil

The Hydrothermal Coordination problem consists of determining an operation policy for hydroelectric and thermoelectric plants within a given planning horizon. In systems with a predominance of hydraulic generation, the operation policy to be adopted should specify the operation of hydroelectric plants, so that hydroelectric resources are used economically and reliably. This work proposes the implementation of reservoir operation rules, using inter-basin water transfer through an optimization model based on Network Flow and Particle Swarm Optimization (PSO). The proposed algorithm aims to obtain an optimized operation policy of power generation reservoirs and consequently to maximize the hydroelectric benefits of the hydrothermal generation system, to reduce the use of thermoelectric plants, the importation and/or energy deficit and to reduce the cost associated with meeting the demand and reduce CO2 emissions from combustion of fossil fuels used by thermoelectric plants. In order to illustrate the efficiency and effectiveness of the proposed approach, it was evaluated by optimizing two case studies using a system with four hydroelectric plants. The first case study does not consider transfer and water and the second case study uses water transfer between rivers. The obtained results illustrate that the proposed model allowed to maximize the hydroelectric resources of a hydrothermal generation system with economy and reliability.

Regenerative hydraulic shock absorber for vehicle applications: prototype design

ABSTRACT This paper presents a novel prototype design solution of the regenerative hydraulic shock absorber and a novel unique methodology for the calculation of the dynamic strength of the proposed device. The proposed calculation methodology includes a definition of the dynamic load which acts on the device, the calculation of the piston rod buckling strength, the calculation of the welded joint, the calculation of the bolt connection, the calculation of the torsional spring, and the calculation of the screw connection. Additionally, the methodology for the selection of a hydraulic motor, electric generator (alternator) and electric battery is proposed which includes the definitions of the main dimensions of the hydraulic cylinder, selection of the vehicle driving mode and a schematic diagram of the simplified mathematical bond graph model of the proposed regenerative hydraulic shock absorber. A numerical example of regenerative hydraulic shock absorber dynamic strength calculation is made for a 1500 kg vehicle. The dimensions obtained by the proposed methodology have similar values to the dimensions of conventional suspensions or shock absorbers that are used today in real vehicles. The proposed calculation methodology can be used to construct different types of regenerative suspensions for real vehicle application. By simulating the mathematical bond graph model of the presented device, it was possible to harvest a maximum regenerative power of 526 W and an average regenerative power of 224 W.

Hardware-Simulator Development and Implementation for Hydraulic Turbine Generation Systems in a District Heating System

This paper presents not only a hardware-simulator development for hydraulic turbine generation systems (HTGS) in a district heating system (DHS) but also its control strategies and sequence. Generally, a DHS uses a differential pressure control valve (DPCV) to supply high-pressure–high-temperature fluids for customers depending on distance. However, long-term exposure of the DPCV to fluids increases the probability of cavitation and leads to heat loss in an event of cavitation. Therefore, a HTGS was introduced to solve this problem. It performs differential pressure control of the fluids, replaces the DPCV, and converts excess energy wasted by the DPCV to electrical energy. In this paper, the development of a hardware-simulator for HTGSs with a back-to-back converter, which uses two-level topologies, is proposed; moreover, control strategies and sequence used in this design are presented. The performance and validity of the proposed hardware-simulator and its control strategies are demonstrated by experimental results.

The Nonlinear Equivalent Input Disturbance Coordinated Control for Enhancing the Stability of Hydraulic Generator System

Hydraulic generator plays more important roles as a renewable clean energy in improving stability. As hydraulic generator enjoys strong nonlinear properties, traditional linearized control method may holds worse adaptability for vary disturbances. In order to solve the problem, a Nonlinear Equivalent Input Disturbance Coordinated Control (NEIDCC) method is proposed in this paper. The objective functions related to system control performance are firstly determined. Then the multi-objective equations satisfying the Brunovsky normal form are derived, by which the nonlinear control problem is transformed to linear space to be solved. The nonlinear equivalent control law is obtained from the linear law by calculating the Γ derivative of the objective functions. When the system is subjected to different disturbances, the designed NEIDCC control law supports dynamic damping by observing the disturbance to stabilize the oscillations. As a result, the control system holds good performance. The simulation results of the designed hydraulic turbine generator control system demonstrate the effectiveness of the NEIDCC method.

Optimization of the integration among traditional fossil fuels, clean energies, renewable sources, and energy storages: An MILP model for the coupled electric power, hydraulic, and natural gas systems

This paper presents a Mixed Integer Linear Programming (MILP) formulation to optimize the Security Constrained Unit Commitment problem, integrating three areas: electrical, hydraulic, and natural gas. The model considers thermal generation from natural gas units and other fossil fuel units, hydraulic generation, pumped storage units, hydraulic head effects for the generation and pumping modes, power flow transmission constraints, natural gas supply and transportation, gas flows in single pipelines and pipelines with compressors, and line-pack for gas pipelines. The original model is hard to solve due to nonconvexities and nonlinearities of several constraints, but with the application of correct linearization techniques, accurate MILP models can be efficiently obtained and solved. The proposed MILP model differs from most of other approaches available in the literature in that it applies to several types of power generation, and includes a large number of real characteristics of the integrated system.A modified IEEE 31-bus with 2 pumped stations and 7-node natural gas system is presented to illustrate the effectiveness of the proposed model; test cases are solved by commercial package Gurobi. Test results indicate that the proposed approach provides feasible solutions with convenient CPU times. The obtained results are discussed and analyzed through simple graphs.

Analysis of the gyroscopic effect on the hydro-turbine generator unit

Abstract The existence of the gyroscopic effect has significant impact on the stability, dynamical behaviors and vibrational characteristics of the high-speed rotating systems. In this paper, the vibration characteristics of the hydro-turbine generator unit with the gyroscopic effect is analyzed. First, a novel nonlinear mathematical model of the hydro-turbine generator unit with consideration of the gyroscopic effect and multi-degree of freedom is established. Second, the vibration of the shaft system are investigated using time histories, phase trajectories and spectrograms based on an operation hydropower station. Some interesting phenomena are obtained by comparing the vibration laws of the hydraulic generator unit in the cases of both K = 0 (without gyroscopic effect) and K ≠ 0 (with gyroscopic effect). Those phenomena show that the effect of gyroscopic intensifies the vibration to some components of the hydraulic generator unit, and it has significant effect on the safe and stable operation of hydropower stations. Meanwhile, the proposed mathematical model can accurately reflect the influence of gyroscopic effect on the vibration characteristics of the hydro-turbine generator unit. The results of this study provides theoretical basis for the design and installation of hydraulic generator units and the optimal operation of hydropower stations.

Сверхпроводниковые тихоходные электрические машины большой мощности (обзор публикаций)

According to the materials published in the period from 1980 to 2012 [2], different companies obtained 869 patents in the field of superconducting electrical machines (SCEMs). The main line of new developments of SCEMs is focused on low-speed (up to 300—400 rpm) motors for driving the propulsive screws of electrically propulsed vessels with capacities from 1 to 40 MW, as well as wind generators (WGs) for rotation frequencies 8—12 rpm and capacity up to 20 MW. High-speed aircraft SCEMs are beyond the scope of this article. As regards superconducting hydro generators, they do not seem to receive wide use since they do not yield noticeable advantages for hydraulic power generation.

Estimation of the amplitude of dynamic stresses on the contour of the well in the mountain range by the parameters of bench tests of hydraulic oscillators

Presented a method for calculating the dynamic tangential stresses around the wellbore, at the time of its treatment by the hydraulic pulse generator, by the values of its characteristics, obtained at the bench test, and the frequency coefficients of influence. Criteria are formulated for selecting the natural frequencies of the measuring sensors that ensure the coincidence of voltages in the array and on the measuring bench.

Объемный гидропривод электрогенератора на транспортном средстве со стабилизацией частоты вращения

Объемный гидропривод электрогенератора на транспортном средстве со стабилизацией частоты вращения

Study on Vibration Transmission among Units in Underground Powerhouse of a Hydropower Station

Research on the safety of powerhouse in a hydropower station is mostly concentrated on the vibration of machinery structure and concrete structure within a single unit. However, few studies have been focused on the vibration transmission among units. Due to the integrity of the powerhouse and the interaction, it is necessary to study the vibration transmission mechanism of powerhouse structure among units. In this paper, field structural vibration tests are conducted in an underground powerhouse of a hydropower station on Yalong River. Additionally, the simplified mechanical models are established to explain the transmission mechanism theoretically. Moreover, a complementary finite element (FE) model is built to replicate the testing conditions for comprehensive analysis. The field tests results show that: (1) the transmission of lateral-river vibration is greater than those of longitude-river vibration and vertical vibration; (2) the vibration transmission of the vibrations that is caused by the low frequency tail fluctuation is basically equal to that of the vibrations caused by rotation of hydraulic generator. The transmission mechanism is demonstrated by the simplified mechanical models and is verified by the FE results. This study can provide guidance for further research on the vibration of underground powerhouse structure.

Gravitational search algorithm applied to fixed head hydrothermal power system with transmission line security constraints

Optimal operation and production planning are important problems for electric power generation systems. Optimal operation of an energy generation system conventionally refers to the minimization of total thermal fuel cost (TTFC). However, the presence of thermal and hydraulic generation units in a power system requires that hydraulic as well as thermal constraints be added to a problem, which is referred to as a short term hydrothermal coordination problem (STHCP). STHCPs assume that the amount of water in the reservoirs of a hydraulic generation unit has no effect on power generation when its net heads are fixed. This study applied a gravitational search algorithm (GSA) for the solution of a STHCP with fixed head. The probable electrical and hydraulic constraints of the problem have been provided by punishment function method. Line losses of the power system were calculated using the Newton-Raphson load flow method. Two different cases, where transfer capacities of transmission lines were neglected and included, were set up, and the problem was solved for both cases. Transfer capacities of transmission lines were included to make the problem more complex and realistic. Solutions for both cases were discussed.

Visualization research on the influence of an ultrasonic degassing system on the operation of a hydraulic gear pump

Gear pumps make a group of the most popular hydraulic energy generators. Research and development works concerning those units have been going on for decades, and thanks to them gear pumps feature very good operating parameters. However, even well-designed gear pumps will not work properly if the physical properties of the working fluid are incorrect. One of such properties is compressibility of the fluid, which largely depends on the amount of gas dissolved in the medium. For this reason, the aim is to reduce the amount of gas dissolved in the working medium. It can be done using both chemical and physical methods. Because chemical methods can affect the chemical composition of the working fluid, it is the physical methods that are usually used in hydraulic systems. This paper presents preliminary visualization research into the influence of an ultrasonic degassing system on the operation of a hydraulic gear pump. Apart from that, operation of such a system and its theoretical impact on the work of the gear pump is discussed Experimental study, using a high-speed camera, was carried out in order to verify the theoretical description.

Automation with renewable energy to optimize the exploitation of water supply networks in Ninh Thuan province

The research that was conducted on the water supply network of Phan Rang city, Ninh Thuan province, is aimed at using renewable energy to optimize the management and reduce the water loss. The research has conducted DMA (District Metering Area) setup, construction and installation of flow meter and pressure reducing valve chamber for flow and pressure control with active pressure regulation, and the use of hydraulic power generator to generate power at the site. Research results provide management agencies, in particular, water supply companies, with optimal solutions in network management and energy saving, reducing the amount of water loss effectively, thereby increasing revenue and saving clean water - precious resources are gradually depleted.

Elementary Introduction of Way of Localization of Composite Sliding Bearing for Hydroelectric Engineering

This article describes the process of replacing imported bearings with domestic composite sliding bearings in the hydroelectric engineering industry from three main aspects: thrust bearing of hydraulic generator, water distributor bearing of hydraulic turbine and spherical plain bearing of steel gate of hydraulic metal structure; expounds that we have adopted the development mode of imitation and independent innovation instead of plagiarism or re-innovation after technology introduction. In the process of domestic development, we relied on our continuous learning and innovation, focused on intellectual property protection, and aimed at the advanced international level; summarizes the achievements made in the application technology level of domestic products through our own efforts over the past 40 years, i.e. achieving the replacement of imported bearings with domestic bearings and realizing the export of domestic bearings; and presents the prospect of application of composite sliding bearings in hydroelectric engineering.

Potential Analysis of Small Hydraulic Generation Using Irrigation Facilities

Potential Analysis of Small Hydraulic Generation Using Irrigation Facilities

Intermittent wave energy generation system with hydraulic energy storage and pressure control for stable power output

In this paper, we introduced an intermittent wave energy generator (IWEG) system with hydraulic power take-off (PTO) including accumulator storage parts. To convert unsteady wave energy into intermittent but stable electrical output power, theoretical models, including wave energy capture, hydraulic energy storage, and torque balance between hydraulic motor and electrical generator, have been developed. Then, the integrated IWEG simulator was constructed and tested at the Ningbo Institute of Technology. Through a series of experimental tests, the relationship between operating flow rates and pressure drops across the hydraulic motor was established. Furthermore, on the basis of the pressure drop signal, we proposed a feedback control method on the basis of the pressure drop database as the feedback control signal to eliminate the disturbance of periodic peak pressure impulse through the regulation of the opening ratio of a proportional flow valve and achieved the effective and stable electric power output, albeit intermittently. Compared with the previous complex control theories and algorithms, this method can keep the power output more stable over a wide range of operating conditions. Furthermore, experimental tests indicate that the IWEG system, with hydraulic PTO, including hydraulic accumulator and proportional flow control valve, is simple, reliable, and easy to control. Most importantly, the real-time power output is stable, and power quality and generation efficiency are significantly improved.

Research on an Axial Maglev Device With Primary Superconductive Coils for a 1000 MW Hydraulic Generator Set

Hydraulic turbogenerators are widely used in hydroelectric power systems. Because of the heavy axial gravitation load of the rotor and main shaft, problems with heat and friction are unavoidable, and will cause mechanical abrasion. To solve these problems, this paper presents a superconducting induction magnetic levitation device for hydraulic generator systems. The induction maglev device has advantages including a simple structure, inherent dynamic stability, large air-gap, and high controllability. Based on the performance of MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> superconducting wires, ac superconducting windings are implemented to increase the levitation force. A coreless structure is used to avoid the core saturation. The basic structure and principles are introduced. The ac losses of MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> winding are deprived. According to the calculated magnetic field distribution, the ac loss power of the MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> winding is estimated under different currents. In addition, the levitation force and rotation torque are calculated and analyzed under different conditions. All the results show the proposed device is well suited for the deload application of thrust bearings in hydraulic turbogenerators.

Design and Analysis of a Superconducting Induction Magnetic Levitation Device for Vertical Hydraulic Generator

Design and Analysis of a Superconducting Induction Magnetic Levitation Device for Vertical Hydraulic Generator

The dynamic hydropower troubleshooting information based on EMD multi-scale feature entropy extraction

Hydropower is a kind of clean energy which is renewable and pollution-free with low operating costs. However, the vibration of the hydraulic turbine generator which has not yet been effectively resolved has seriously affected the efficiency of hydroelectricity exploitation. This report includes the multi-scale entropy analysis of the fluctuating signals created by pressure within the hydraulic turbine's draft tube. The analysis is based on the empirical model decomposition method, using the mobile communication technology. The signal was resolved into multiple intrinsic mode functions (IMF) situated on a local characteristic time scale. Energy level indexes were then calculated according to these IMFs. These indexes were then used in order to establish the entropy's multi-scale characteristic value. Next, the entropy's value was used as eigenvector for the identification of different failure modes. Tests were conducted using the fluctuations in the pressure signals created through the mobile communication. The results of these tests show that this method is highly accurate and that it is effective when used to extract eigenvectors in the context of hydraulic turbine generator units. The method was relatively accurate where the extraction of highly complex and specific data relating to the dynamic characteristics of a hydraulic turbine generator was concerned.