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Date submitted2022-10-26
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Date accepted2023-02-13
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Date published2023-07-19
Determination of the grid impedance in power consumption modes with harmonics
The paper investigates the harmonic impedance determination of the power supply system of a mining enterprise. This parameter is important when calculating modes with voltage distortions, since the determined parameters of harmonic currents and voltages significantly depend on its value, which allow the most accurate modeling of processes in the presence of distortions in voltage and current. The power supply system of subsurface mining is considered, which is characterized by a significant branching of the electrical network and the presence of powerful nonlinear loads leading to a decrease in the power quality at a production site. The modernization of the mining process, the integration of automated electrical drive systems, renewable energy sources, energy-saving technologies lead to an increase in the energy efficiency of production, but also to a decrease in the power quality, in particular, to an increase in the level of voltage harmonics. The problem of determining the grid harmonic impedance is solved in order to improve the quality of design and operation of power supply systems for mining enterprises, taking into account the peculiarities of their workload in the extraction of solid minerals by underground method. The paper considers the possibility of determining the grid impedance based on the measurement of non-characteristic harmonics generated by a special nonlinear load. A thyristor power controller based on phase regulation of the output voltage is considered as such a load. Simulation computer modeling and experimental studies on a laboratory test bench are used to confirm the proposed method. The recommendations for selecting load parameters and measuring device connection nodes have been developed.
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Date submitted2021-01-20
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Date accepted2021-03-15
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Date published2021-04-26
Improving the quality of electricity in the power supply systems of the mineral resource complex with hybrid filter-compensating devices
- Authors:
- Yurii A. Sychev
- Roman Yu. Zimin
The urgency and necessity of choosing and justifying the structures of hybrid filter-compensating devices based on series and parallel active filters to improve the quality of electricity in the power supply systems of enterprises of the mineral resource complex is shown. Mathematical models of hybrid filter compensating devices based on parallel and series active filters have been developed. Based on these mathematical models, computer simulation models of the indicated hybrid structures have been developed. The results of simulation showed the effectiveness of the correction of power quality indicators in terms of reducing the level of higher harmonics of current and voltage, as well as voltage deviations. The degree of influence of filter-compensating devices on the power quality indicators, which determine the continuity and stability of the technological process at the enterprises of the mineral resource complex, have been revealed. It has been established that a hybrid filter-compensating device based on a parallel active filter can reduce the level of higher harmonics of current and voltage by more than 90 and 70 %, respectively, and based on a series active filter, it can reduce the level of higher harmonics of voltage by more than 80 %. Based on the simulation results, the possibility of compensating for the reactive power of a hybrid structure based on parallel active and passive filters has been revealed. The possibility of integrating hybrid filter-compensating devices into more complex multifunctional electrical systems for the automated improvement of the quality of electricity is substantiated, as well as the expediency and prospects of their use in combined power supply systems based on the parallel operation of centralized and autonomous sources of distributed generation.
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Date submitted2019-03-31
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Date accepted2019-08-25
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Date published2020-02-25
Cascade frequency converters control features
The structures of systems with high-voltage cascade frequency converters containing multi-winding transformers and low-voltage low-power converters connected in series at each output phase of the load are considered. Low-voltage blocks contain three-phase diode or active rectifiers, DC capacitor filters, single-phase stand-alone voltage inverters and block disconnecting devices in partial modes (in case of failure when part of the blocks are disconnected). The possibilities of operation of cascade converters are determined, equations for correcting tasks to units in partial modes are given, tables of correction of tasks with estimates of achievable load characteristics are proposed. The results of experiments on the model of a powerful installation with a cascade frequency converter are presented, confirming the possibility of ensuring the symmetry of the load currents when disconnecting part of the blocks and the asymmetry of the circuit.
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Date submitted2018-10-27
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Date accepted2019-01-04
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Date published2019-04-23
Application of an active rectifier used to mitigate currents distortion in 6-10 kV distribution grids
The paper addresses issues of using the active rectifier in partially loaded variable frequency drive as active filter in the conditions of non-sinusoidal current and voltage disturbances caused by the presence of high-power non-linear load in the grid. The topology of transformless three-level converter for 6-10 kV suitable for proposed solution has been presented and its mathematical model has been de-rived. Based on the model, the direct power control algorithm with ability to compensate non-linear currents has been designed. The investigation of active rectifier efficiency was performed depending on the relation between linear and non-linear load currents of the grid node, as well as on active power load of the active rectifier. Efficiency analysis was based on the developed computer model of the grid node with connected non-linear load simultaneously with the variable frequency drive with active rectifier.
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Date submitted2015-12-24
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Date accepted2016-02-04
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Date published2016-12-23
Geodynamic methods for assessing methane distribution in bituminous coal deposits and measures to intensify methane fluxes during mine gas drainage
- Authors:
- E. V. Goncharov
- S. V. Tsirel
This paper explores states of methane within the coal bearing stratum and shows heavy dependency of the intrastratal gas migration on the forms of porous space and petrographic properties of coal. The adsorbed methane is found to be predominant in the coal of Kuznetsk Basin. Different forms of coal diffusion and filtration are described revealing their dependency on geological and thermodynamic conditions. The paper provides justification for the primary focus on geodynamic processes when designing gas drainage systems and applicability of morphometric methods and remote sensing data for their identification. The significance of researches into the processes activating exothermic reactions resulting in methane transition to free state is explained. The paper presents the results of using seismic-acoustic stimulation techniques as one of the practical approaches to addressing this issue. Results of successful industrial testing have been compared with the results of numerical modelling of stress-strain state, which can also be managed through seismic-acoustic stimulation.
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Date submitted2015-08-13
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Date accepted2015-10-29
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Date published2016-04-22
Multicriteria estimation of bearing capacity of geomaterials
- Authors:
- I. A. Brigadnov
In the article the problem of an estimation of bearing capacity of geomaterials as a deform-able solid is considered in the current configuration, which may be as the reference (undeformed) or the actual (deformed). We propose an original variational approach to the problem for stresses in selected subdomains, in which, depending on different engineering considerations, average in-tegral values of different component of stresses are estimated and from their aggregate the bearing capacity of the current configuration of the solid is estimated regarding to given external influ-ences. In each of the selected subdomain the weakest stress field is obtained which is globally bal-anced with external influences. For example, the assessment of the average integral hydrostatic pressure is needed for study of bearing capacity of geomaterials.
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Date submitted2015-08-19
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Date accepted2015-10-17
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Date published2016-04-22
Development of institute of financial control in construction
- Authors:
- V. P. Grakhov
- O. L. Chazova
The article is devoted to the complex research of development of Institute of financial control in construction. Based on the analysis of approaches of researchers to definition of concept «financial control», sets out its objectives and importance. Identifies and describes the characteristic features of state and non-state financial control. To examine the existing mechanisms of financial control system in construction in General, to prevent violations and to create the basis for the adoption of specific management decisions, it is proposed to study three main areas. Special attention is paid to the analysis of the current legislation in the field of formation of financial control in the construction and practice of its application. Presents substantial changes in the legal regulation of the contract system in the sphere of procurement for state and municipal needs, including the adjustment of the scheme of carrying out of competitive procedures by the customer. In this regard, an important role plays the method of calculation of the final rating of participants of procurement procedures, allowing to determine the winner in accordance with predetermined criteria and their weighting factors. This area is also complemented by the consideration of issues related to the establishment of the procedure for the implementation of banking support contracts, allowing to provide the customer more effective control over the observance of contractual obligations with suppliers (contractors, performers). The conducted researches allow to draw a conclusion about the need to rethink and address issues related to efficiency of use of budget investments in objects of capital construction. In this regard, the main priorities of improving financial control in the construction industry to achieve the desired rates of economic development.
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Date submitted2014-12-20
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Date accepted2015-02-05
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Date published2015-12-25
Synergetic changes of tribochemical properties in the heterogeneous systems containing surface modified metals
- Authors:
- A. G. Syrkov
In the article tribochemical properties and synergetic effects in lubricants with metal addi-tives, characterized by surface modifcations, have been analysed. The priority results of measur-ings friction coefficient (f) and friction force (F fr) are given for heterogeneous systems in the form of И-20 oil with solid Al-additives, contatiing dispersed aluminium, with surface-modified triamon (Т), alkamon (A) and ethylhydridsiloxane according to various programs. It has been educed that with all other things being equal, triamon underlayers introduction into Al-additives with the external chemisorpted ethylhydridsiloxane layer results in the decrease of F fr and f in the system in proportion to the Т-underlayer number reduction from three to one. It has been discovered that the use of low-molecular Т-underlayer in Al-additives is a delicate method of summand value regulation (from 10,8 to 13,2 Н), accountable for intermolecular forces in the boundary fritction equation in the tribological pair applied.
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Date submitted2009-10-18
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Date accepted2009-12-09
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Date published2010-09-22
Influence of blocky-hierarchy structure of geological medium on the forming of natural and technogenic geodynamic fields in the North-West part of the Amur geoblock
- Authors:
- I. Yu. Rasskazov
- B. G. Saksin
On the example of the South-Argun uranium ore district of Zabaikalie consideration is given to the interaction of regional and local fields of stresses. The district includes a number of deposits prone to rock bursts. The performed analysis contains data on recent geodynamics of the explored part of the Amur geoblock as well as on geomechanical and geologo-structural materials of Tulukuev caldera and of Antey deposit. It is shown that with the use of the M.A. Sadovsky relationship the indices of local structural forms of a row are subjected to unified laws of deformation and fracturing. Conclusion was made that at the beginning of deposit exploitation the direction of action of stress field within rock mass conformed to regional one, and then it considerably changed under influence of large-scale mining operations.
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Date submitted2009-10-21
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Date accepted2009-12-16
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Date published2010-09-22
Geomechanical foundations of the safe extraction in joint mining of rich, coppery and ore patches in deep ore mines at Тalnakh
- Authors:
- V. A. Zvezdkin
- A. A. Andreev
The paper deals with the specific formation of stress fields in ore-bearing intrusions at the Oktiabrsky and Talnakh ore deposits with due account of depth of occurrence and formation of tectonic disturbances. The authors have investigated the influence of mining works on stress state of ore-bearing portion of the intrusion. The relationships were obtained in terms of the formation of stress fields in the intrusion during its undermining, overmining and joint mining of several ore deposits. Some recommendations are given for mining of series of ore formations at the Oktiabrsky and Talnakh deposits.
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Date submitted2009-10-29
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Date accepted2009-12-26
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Date published2010-09-22
Control system of rock pressure at the «Antey» deposit
- Authors:
- B. A. Prosekin
- E. A. Ilin
The paper deals with the geomechanical monitoring system of the Antey deposits of uranium ores. Characteristics of the methods and means for rock pressure control are given.
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Date submitted2009-10-14
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Date accepted2009-12-11
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Date published2010-09-22
Investigation of present-day stress-strain state of rock mass by the results of observations at geodynamic polygons
- Authors:
- S. N. Savchenko
- E. V. Kasparyan
- Yu. G. Smagina
The methods are suggested for treatment of the results of optical distance and levelling measurements at the underground geodynamic polygons involving in their calculation the tensors of additional stresses and deformations, component of rotation and specific energy of deformability. As an example, consideration is given to changes in time of movements, deformations and specific energy of deformability at one of geodynamic polygons of the Kola peninsular.
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Date submitted2009-07-25
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Date accepted2009-09-09
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Date published2010-04-22
The use of data on stress-strain state of rock mass in solutions of mining-and-technical tasks on the example of the Tishin ore mine
The Permion State Technical University and ASE «VNIItsvetmet» have carried out in situ measurements of stress-strain state at the Tishinsky lead-zinc ore deposit. Measurements and interpretation of deformations and stresses caused by excavation were used. Complex of researches made it possible to solve some important problems for safeguarding effective and secure ore production ore on deep level.
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Date submitted2009-07-12
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Date accepted2009-09-16
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Date published2010-04-22
Numerical assessment of stress-strain field in vicinity of large open pit mine taking into account geomechanical, geological and mining factors
The results of modeling of rock mass stress state in the vicinity of large open pit mine using finite-elements method are represented. The model allows to take into account the influence of large-scale fractures. The initiation of boundary conditions is based on the results of determination of stress parameters in situ. The locations of risk areas near the slope are defined.
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Date submitted2009-07-09
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Date accepted2009-09-03
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Date published2010-04-22
The stress-strain state of the massive of the loose ores in the Yakovlevsky deposit around the minings which were drilled with the combines or with drilling-blast technology
The article presents the consistent patterns of the changes in stress-strain state of the massive by the minings of the first stage of protective overlapping in the Yakovlevsky deposit. The change of the stress-strain condition of the rock massive, which is weaked by the mining was determined by the method of finite elements. The stresses distribution in the massive, the displacement of the contour of the minings, the size of conditional zones of non-linear deformations has been obtained. For stoping passes at the first stage the cutting with combine and application of fastening with the anchors has been suggested.