Study on the Modes of Operation of a Multi-Machine Installations with Mechanical Reduction

2019 ◽  
pp. 12-22
Author(s):  
A. M. Oleynikov ◽  
L. N. Kanov
Keyword(s):  
Mathematical Description ◽  
Reactive Power ◽  
Maximum Efficiency ◽  
Wind Flow ◽  
System Of Equations ◽  
Mechanical Equilibrium ◽  
Synchronous Generators ◽  
Electromagnetic Excitation ◽  
Number Of Generators ◽  
Wide Range

The paper gives the description of the original wind electrical installation with mechanical reduction in which the output of vertical axis wind turbine with rather low rotation speed over multiplicator is distributed to a certain number of generators. The number of acting generators is determined by the output of actual operating wind stream at each moment. According to this constructive scheme, it is possible to provide effective and with maximum efficiency installation work in a wide range of wind speeds and under any schedule issued to the consumer of electricity. As there are no any experience in using such complexes, mathematical description of its main elements is given, namely windwheels, generators with electromagnetic excitation of magnetic electrical type, then their interaction with windwheel, and also the results of mathematical modeling of work system regimes under using the offered system of equations. The basis for the mathematical description of the main elements of the installation – synchronous generators – are the system of equations of electrical and mechanical equilibrium in relative units in rotating coordinates without considering saturation of the magnetic circuit. The equation of mechanical equilibrium systems includes torque and brake windwheel electromagnetic moments of generators with taking into account the reduction coefficients and friction. In addition, we specify the alternator rotor dynamics resulting from continuous torque of windwheel fluctuations under the influence of unsteady wind flow and wind speed serving as the original variable is modeled by a set of sinusoids. Model simplification is achieved by equivalization of similar generators and by disregarding these transitions with a small time constant. Calculation the installation with synchronous generators of two types of small and medium capacity taking into account the operational factors allowed us to demonstrate the logic of interactions in the main elements of the reported complex in the process of converting wind flow into the generated active and reactive power. We have shown the possibility of stable system work under changeable wind stream condition by regulating of the plant blade angle and with simultaneous varying of generator number of different types. All these are in great interest for project organizations and power producers.

scholarly journals Indirect Vector-Controlled Brushless Doubly-Fed Twin-Stator Induction Generator for Wind Energy Conversion Application

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4174
Author(s):  
Mona I. Abdelkader ◽  
Ahmed K. Abdelsalam ◽  
Ahmed A. Hossameldin
Keyword(s):  
Wind Energy ◽  
Energy Conversion ◽  
Reactive Power ◽  
Operating Conditions ◽  
Velocity Variation ◽  
Induction Generator ◽  
Synchronous Generators ◽  
Wind Energy Conversion ◽  
Wide Range ◽  
Doubly Fed

Wind energy conversion systems (WECSs) seem certain to play a major part in the world’s energy future due to their known high power capacity. The maximum power tracking is unavoidable due to the wind velocity variation and the non-linear relation with the turbine mechanical power. Commercial wind turbines are commonly coupled to either doubly-fed induction generators (DFIGs), wound rotor synchronous generators (WRSG) or permanent magnet synchronous generators (PMSGs). The DFIG-based WECS has several advantages over others. One of which is the power converter in such systems only deals with rotor power, hence the converter rating can run at reduced power rating. However, DFIG has the famous disadvantage of the presence of slip rings which leads to increased maintenance costs and outage times. Hence, brushless doublyfed induction machines (BDFIMs) can be considered as a viable alternative at the penalty of complicated controller requirement and limited decoupling control capability due to the machine’s non-linearity. In this paper, an enhanced performance indirect vector controller is proposed for WECS based on brushless doubly-fed twin-stator induction generator (BDFTSIG). The presented controller offers (i) simplified implementation, (ii) decoupled active-reactive power control, and (iii) a wide range of operation. The proposed controller performance is investigated under various loading conditions showing enhanced transient and minimal steady-state oscillations in addition to complete active/reactive power decoupling. The rigorous simulation and experimental results verify the claimed controller effectiveness under all possible operating conditions for sub- and super-synchronous speed range.

LIQUIDUS THERMO-BAROMETER FOR THE MODELING OF MAGNETITE — MELT EQUILIBRIUM

2018 ◽  
pp. 71-80
Author(s):  
N. S. Aryaeva ◽  
E. V. Koptev-Dvornikov ◽  
D. A. Bychkov
Keyword(s):  
Experimental Data ◽  
Liquidus Temperature ◽  
Vertical Structure ◽  
Maximum Error ◽  
Silicate Melt ◽  
System Of Equations ◽  
Wide Range ◽  
Basaltic Melts ◽  
Multidimensional Statistics

A system of equations of thermobarometer for magnetite-silicate melt equilibrium was obtained by method of multidimensional statistics of 93 experimental data of a magnetite solubility in basaltic melts. Equations reproduce experimental data in a wide range of basalt compositions, temperatures and pressures with small errors. Verification of thermobarometers showed the maximum error in liquidus temperature reproducing does not exceed ±7 °C. The level of cumulative magnetite appearance in the vertical structure of Tsypringa, Kivakka, Burakovsky intrusions predicted with errors from ±10 to ±50 m.

scholarly journals Voltage Stability of Power Systems with Renewable-Energy Inverter-Based Generators: A Review

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 115
Author(s):  
Nasser Hosseinzadeh ◽  
Asma Aziz ◽  
Apel Mahmud ◽  
Ameen Gargoom ◽  
Mahbub Rabbani
Keyword(s):  
Renewable Energy ◽  
Power Systems ◽  
Voltage Stability ◽  
Reactive Power ◽  
Power Grid ◽  
Renewable Energy Sources ◽  
Electrical Power ◽  
System Stability ◽  
Special Issue ◽  
Synchronous Generators

The main purpose of developing microgrids (MGs) is to facilitate the integration of renewable energy sources (RESs) into the power grid. RESs are normally connected to the grid via power electronic inverters. As various types of RESs are increasingly being connected to the electrical power grid, power systems of the near future will have more inverter-based generators (IBGs) instead of synchronous machines. Since IBGs have significant differences in their characteristics compared to synchronous generators (SGs), particularly concerning their inertia and capability to provide reactive power, their impacts on the system dynamics are different compared to SGs. In particular, system stability analysis will require new approaches. As such, research is currently being conducted on the stability of power systems with the inclusion of IBGs. This review article is intended to be a preface to the Special Issue on Voltage Stability of Microgrids in Power Systems. It presents a comprehensive review of the literature on voltage stability of power systems with a relatively high percentage of IBGs in the generation mix of the system. As the research is developing rapidly in this field, it is understood that by the time that this article is published, and further in the future, there will be many more new developments in this area. Certainly, other articles in this special issue will highlight some other important aspects of the voltage stability of microgrids.

scholarly journals Hybrid ZnO/MoS2 Core/Sheath Heterostructures for Photoelectrochemical Water Splitting

Applied Nano ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 148-161
Author(s):  
Katerina Govatsi ◽  
Aspasia Antonelou ◽  
Labrini Sygellou ◽  
Stylianos G. Neophytides ◽  
Spyros N. Yannopoulos
Keyword(s):  
Visible Light ◽  
Wide Band ◽  
Nanowire Arrays ◽  
Maximum Efficiency ◽  
Light Illumination ◽  
Wide Band Gap ◽  
Long Term Stability ◽  
Visible Light Illumination ◽  
Nanowire Surface ◽  
Wide Range

The rational synthesis of semiconducting materials with enhanced photoelectrocatalytic efficiency under visible light illumination is a long-standing issue. ZnO has been systematically explored in this field, as it offers the feasibility to grow a wide range of nanocrystal morphology; however, its wide band gap precludes visible light absorption. We report on a novel method for the controlled growth of semiconductor heterostructures and, in particular, core/sheath ZnO/MoS2 nanowire arrays and the evaluation of their photoelectrochemical efficiency in oxygen evolution reaction. ZnO nanowire arrays, with a narrow distribution of nanowire diameters, were grown on FTO substrates by chemical bath deposition. Layers of Mo metal at various thicknesses were sputtered on the nanowire surface, and the Mo layers were sulfurized at low temperature, providing in a controlled way few layers of MoS2, in the range from one to three monolayers. The heterostructures were characterized by electron microscopy (SEM, TEM) and spectroscopy (XPS, Raman, PL). The photoelectrochemical properties of the heterostructures were found to depend on the thickness of the pre-deposited Mo film, exhibiting maximum efficiency for moderate values of Mo film thickness. Long-term stability, in relation to similar heterostructures in the literature, has been observed.

Operation Characteristics of Zone 3 Distance Protection in Wind Power Systems with Fixed-Speed Induction Generators

2011 ◽  
Vol 12 (4) ◽  
Author(s):  
Shenghu Li
Keyword(s):  
Power Systems ◽  
Wind Power ◽  
Reactive Power ◽  
Flow Analysis ◽  
Load Flow ◽  
Synchronous Generators ◽  
Induction Generators ◽  
Load Flow Analysis ◽  
Wind Power Systems ◽  
Operation Characteristics

The induction generators (IGs) are basic to wind energy conversion. They produce the active power and consume the reactive power, with the voltage characteristics fragile compared with that of the synchronous generators and doubly-fed IGs. In the stressed system states, they may intensify var imbalance, yielding undesirable operation of zone 3 impedance relays.In this paper, the operation characteristics of the zone 3 relays in the wind power systems is studied. With the theoretical and load flow analysis, it is proved that the equivalent impedance of the IGs lies in the 2nd quadrature, possibly seen as the backward faults by the mho relays, i.e. the apparent impedance enters into the protection region from the left side. The undesirable operation may be caused by more wind power, larger load, less var compensation, and larger torque angle.

scholarly journals Distributed Generation Placement in Radial Distribution Networks using a Bat-inspired Algorithm

DYNA ◽  
2015 ◽  
Vol 82 (192) ◽  
pp. 60-67 ◽  
Author(s):  
John Edwin Candelo-Becerra ◽  
Helman Hernández-Riaño
Keyword(s):  
Distributed Generation ◽  
Radial Distribution ◽  
Distribution Systems ◽  
Reactive Power ◽  
Distribution Networks ◽  
Power Losses ◽  
Number Of Generators ◽  
Metaheuristic Techniques ◽  
Distributed Generation Placement ◽  
Made In

<p>Distributed generation (DG) is an important issue for distribution networks due to the improvement in power losses, but the location and size of generators could be a difficult task for exact techniques. The metaheuristic techniques have become a better option to determine good solutions and in this paper the application of a bat-inspired algorithm (BA) to a problem of location and size of distributed generation in radial distribution systems is presented. A comparison between particle swarm optimization (PSO) and BA was made in the 33-node and 69-node test feeders, using as scenarios the change in active and reactive power, and the number of generators. PSO and BA found good results for small number and capacities of generators, but BA obtained better results for difficult problems and converged faster for all scenarios. The maximum active power injections to reduce power losses in the distribution networks were found for the five scenarios.</p>

scholarly journals Optimization of nitrogen and phosphorus removal from pig slaughterhouse and packing plant wastewater through electrocoagulation in a batch reactor

2018 ◽  
Vol 13 (5) ◽  
pp. 1
Author(s):  
Fábio Orssatto ◽  
Maria Hermínia Ferreira Tavares ◽  
Flávia Manente da Silva ◽  
Eduardo Eyng ◽  
Leandro Fleck
Keyword(s):  
Total Phosphorus ◽  
Retention Time ◽  
Batch Reactor ◽  
Maximum Efficiency ◽  
Nitrogen And Phosphorus ◽  
Nitrogen And Phosphorus Removal ◽  
Treatment Conditions ◽  
Surface Graph ◽  
Wide Range ◽  
Kjeldahl Nitrogen

This work evaluated the removal of total Kjeldahl nitrogen (TKN) and total phosphorus (P) through electrocoagulation and used aluminum electrodes to optimize the potential differential (pd) and hydraulic retention time (HRT) variables in a batch reactor. The experimental design used was Rotatable Central Composite Design (RCCD). The application of the electrocoagulation in the treatment of effluents from pig slaughterhouses and packing plants proved to be efficient in relation to the removal of TKN and total phosphorus, obtaining maximum efficiency equal to 67.15% and 99%, respectively. The maximum TKN removal value was found in Test 12, where treatment conditions were 30 minutes for HRT and 20 volts for pd, which corresponds to 0.86 A of electric current and a current density of 17.2 mA cm-2. For P, the only test that removed below 99% was the first. Through statistical analyses, it was only possible to obtain a mathematical model for TKN removal. While the response surface graph did not present a defined range of the best conditions for the independent variables, it was possible to observe the tendency for better removal, a wide range of pd and values over 30 minutes for retention time.

scholarly journals Hardware solutions for energy-efficient control technologies of distribution network objects based on power semiconductor devices

2021 ◽  
Vol 24 (1) ◽  
pp. 91-96
Author(s):  
V. N. Krysanov ◽  
◽  
V. L. Burkovskii ◽  
I. A. Khaychenko ◽  
◽  
...  
Keyword(s):  
Reactive Power ◽  
Short Circuit ◽  
Distribution Networks ◽  
Voltage Transformer ◽  
Industrial Facilities ◽  
Power Semiconductor ◽  
Wide Range ◽  
Electric Power Sector ◽  
Power Part ◽  
Control Technologies

The article considers topical issues in development of energysaving technologies to optimize the control of distribution networks according to the criterion of minimum power losses. The technology consists in introducing new hardware to control the modes based on static devices. Based on the analysis of the existing hardware created to control the modes of distributio networks, the developed circuitry solutions of the power part and the control system of the multifunctional thyristor voltage transformer and hybrid thyristor capacitor are proposed. Their main technical characteristics and ways to reduce voltage asymmetry, limiting short circuit currents and regulating reactive power are det ermined. The use of software and hardware solutions was recommended for a wide range of energy conservation tasks, both in the electric power sector and at the level of industrial facilities

scholarly journals A New 4500-HP Gas Turbine for Pipeline Industrial Service

1970 ◽  
Author(s):  
R. R. Oliver ◽  
F. Fraschetti
Keyword(s):  
Gas Turbine ◽  
Mechanical Design ◽  
Maximum Efficiency ◽  
Heavy Duty ◽  
Cooperative Effort ◽  
Package Design ◽  
Wide Range ◽  
Industrial Service ◽  
Design Options ◽  
Regenerative Cycle

This paper describes the performance and mechanical design of a 4500-hp, two shaft heavy duty simple or regenerative cycle gas turbine. This machine resulted from an international cooperative effort of the joint authors’ respective companies. Initially planned for gas pipelines and process applications, a line of load compressors has been integrated into the single package design. Options include indoor or outdoor models and geared or direct mechanical output for applications not served by the integral compressor models. A variable area load turbine nozzle assures maximum efficiency over a wide range of load, speed, and amibient conditions.

A methodology for loss and performance assessment of a variable geometry turbocharger turbine through a new meanline FORTRAN program

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ahmed Ketata ◽  
Zied Driss
Keyword(s):  
Rotational Speed ◽  
Internal Combustion Engines ◽  
Maximum Efficiency ◽  
Variable Geometry ◽  
Mixed Flow ◽  
Content Type ◽  
Variable Geometry Turbocharger ◽  
Nozzle Vane ◽  
Wide Range ◽  
Vane Angle

PurposeVariable geometry turbine (VGT), a key component of modern internal combustion engines (ICE) turbochargers, is increasingly used for better efficiency and reduced exhaust gas emissions. The aim of this study is the development of a new meanline FORTRAN code for accurate performance and loss assessment of VGTs under a wider operating range. This code is a useful alternative tool for engineers for fast design of VGT systems where higher efficiency and minimum loss are being required.Design/methodology/approachThe proposed meanline code was applied to a variable geometry mixed flow turbine at different nozzle vane angles and under a wide range of rotational speed and the expansion ratio. The numerical methodology was validated through a comparison of the predicted performance to test data. The maps of the mass flow rate as well as the efficiency of the VGT system are discussed for different nozzle vane angles under a wide range of rotational speed. Based on the developed model, a breakdown loss analysis was carried out showing a significant effect of the nozzle vane angle on the loss distribution.FindingsResults indicated that the nozzle angle of 70° has led to the maximum efficiency compared to the other investigated nozzle vane angles ranging from 30° up to 80°. The results showed that the passage loss was significantly reduced as the nozzle vane angle increases from 30° up to 70°.Originality/valueThis paper outlines a new meanline approach for variable geometry turbocharger turbines. The developed code presents the novelty of including the effect of the vane radii variation, due to the pivoting mechanism of the nozzle ring. The developed code can be generalized to either radial or mixed flow turbines with or without a VGT system.

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