GEORGIAN TECHNICAL UNIVERSITY SCIENTIFIC AND ENGINEERING CENTRE OF POWER INDUSTRY THREE-PHASE BRIDGE RECTIFIER-INVERTER CONVERTER WITH PULSE-WIDTH CONTROL OF DIRECT CURRENT TRACTION MOTOR

G.KOKHREIDZE, D.LAOSHVILI, D.KOKHREIDZE, I.KURASHVILI

Integral rectifier-inverter conversion system of traction substation by the three-phase bridge circuit with pulse controlled direct current (dc) motor of electric locomotive with pulse-width control is developed. For simplifying process control, IGBT (Insulated Gate Bipolar Transistor) is used as a thyristor key in pulse-width control circuit of the traction motor of the electric locomotive. Starting and traction modes as well as electric regenerative braking of the traction motor during pulse-width control is reviewed. Generated voltage of the motor of series excitation is less than the voltage of the contact system.





NATURE OF SHAFT METHANE

A. ALEKSEEV, E.ULIANOVA, O.RAZUMOV, V.KANIN, A.SKOBLIK, A.TARANIK

Carbonic-isotopic composition of shaft methane is concentrated by heavy isotope with displaced meaning δ 13С from -42 ‰ to -20÷-30 ‰ within the limits of approaching to the burst- risky zone of coal bed, connected with tectonic over-thrust in the area of fracture of crystal foundation. On the contrary, in the zone of strengthened gas emission, connected with apophysis in the area of tectonic fault, at metamorphosis (rank of coal) of the same degree δ 13С of methane is changed weakly and δ 13С of carbon dioxide is decreased from -8‰ to -20 ‰. Approaching of isotope composition of shaft methane with a composition of methane in volcanic gases and thermal springs indicates a possibility of gases’ underlay along thrusts and apophysis in coal beds from depth. By methods of Mössbauer spectroscopy, a presence of ferrous iron in burst-risky coal beds and also its absence in methane-bearing, but not burst-risky are determined, which can be served as a confirmation of abiotic model of forming of “young” methane in coals, which is taking place and at present, at the expense of non-stationary processes of synthesis Fisher – Tropsh on catalyst from compound of ferrous iron.





USAGE OF SOLAR ENERGY IN THE PRODUCTION OF CONCRETE AND IRON CONCRETE

A.NADIRADZE

Results of experimental works for thermal concrete treatment run at Georgian Technical University using helio-chamber suggested and developed by the author are presented. General physical regularities of turning solar energy into the thermal one are described. It is determined, that maximum usage of solar energy is more reasonable in the production of concrete and reinforced concrete articles at the site. It is also possible to use solar energy in the production of bulk concrete and reinforced concrete with obligatory performance of the so called “hothouse effect” method.





COMPUTER PROGRAMME TO DEFINE SIMILARITY CRITERIA ON BASIS OF DIMENSIONAL ANALYSIS

A.M. KULIEV, A. A. NASIBOV

The present work evaluates the definition of all possible forms of Similarity Criteria for physical modeling using a computer program. In the determination of similarity criteria, the program applies the method that is based on dimensional analysis. The flowchart of composed algorithm and the test data were joined to the article. The program was written in programming language C++.





NEW DESIGNS FOR PROCESSES OF SEWAGE PURIFICATION

A.GASHIMOV, K.GURBANOV, R.MEHTIZADE, M.GASANOV

Research results for cleaning waste water of the companies “Isolite” (Mingechaur), Thermal Power Plant and Gas Processing Plant of Orenburg as well as of oil formation water of Baku are presented. Combined physico-chemical cleaning methods including chemical and adsorbtion cleaning under the conditions of the exposure of ozone and high electric fields and discharges were utilized. It was determined, that under the affect of electric discharges in various gas environments as well as under the affect of ozone, the effectiveness of adsorbtion methods of waste water cleaning increased significantly. Based on the results obtained, according to the composition of source water admixture, number of options for adsorption methods of cleaning processes successfully tested in laboratory conditions are proposed. Some results were tested and introduced in relevant production companies.





GENERATOR DAMPING IN COMPLICATED ELECTRIC SYSTEM

M. RUKHVADZE

In mathematical modelling of dynamic stability of power system, asynchronous capacity developed by generators can be considered just when transient process in generators is described by complete Park-Gorev equation. Usage of the latter allows to bring modelling results maximally close to the reality, but in such case it is necessary to know real generator parameters. As a rule, all these parameters either are not known or are known partially. That is why, analysis of the dynamic stability is run either by typical (approximate) parameters, or based on simplified equations, where it is not necessary to know part of these parameters. It is shown how dynamic stability of the power systems may be modeled with simplified equations and at the same time, consider asynchronous capacity of the generators. Modelling results are presented based on which options of using the proposed method are shown.





CALCULATION OF THE VOLUME OF TRANSPORTED OIL USING TANKS AND RESULT ANALYSIS

D. NADIRADZE

On the basis of the proposed new method, calculation of oil volume is conducted by a special calculator stations. Oil parameters (density, viscosity, temperature, pressure, watercut and other sediment content of oil) are determined. New method unlike the old one, includes the calculation of those oil parameters which were not considered before. Using the method of identification of an accurate volume of imported oil, monetary and comparative values of profit are obtained. Respective tables and figures are prepared and presented.





PROBLEMS RELATING TO THE STABILITY OF BANK VAULT OF THE RESERVOIRS LOCATED WITHIN SEISMICALLY ACTIVES ZONES AND WAYS OF THEIR SETTLEMENT

J. KILASONIA

Main reasons of stability failure of the bank vaults surrounding large mountain reservoirs are reviewed. Main role here is granted to the depth hydrodynamic and rheological processes caused by the reservoir fillup and drawdown. It is concluded, that the most dangerous for reservoirs located in the mountain regions of Georgia and for the entire Caucasus regions is the seismic impact, which, most likely, is correlated by the mentioned processes. The principles for designing large, dynamic, finite element model of the reservoir bank vault and tasks of three-component seismogram package are proposed.





OPTIMIZATION OF THE REGIMES OF SEVAN-RASDAN CASCADE OF HYDROPOWER PLANT

L.AGEKYAN, V.SAFARYAN

The work includes eleboration of methods and program of choosing optimum work regimes of Sevan-Hrazdan Cascade of Hydro-Electric Power Plants (HPPs) in the conditions of strict ordering of irrigation regime and water flow the lake Sevan as well as while following daily schedule of power system. The criteria for optimum Cascade work regime are:

1. Minimum lack of coincidence of given and rated Cascade load curves.

2. Provision of load schedule in the conditions of minimum water flow from the lake Sevan by restricting the pass-by water flows around HPPs.

3. Minimization of switching off of Cascade HPPs.

PRE-STRESSED IRON CONCRETE BODY OF NUCLEAR POWER PLANT REACTOR

A. KUBANEISHVILI, M.KALABEGISHVILI

Construction of high pressure pre-stressed iron concrete body is described. An issue of body creation is decided experimentally and theoretically. High pressure body is an iron concrete structure of a cylinder shape made of coaxially located external and internal envelopes with the clearance between them. Cement slurry is pumped into the clearance. Internal envelope at this moment squeezes and the external one – expands. Pressure is brought to necessary preliminary concrete reduction of the internal envelope considering all the losses as a result of which the canals with mixed pre-stressed reinforcement are filled with slurry. Theoretical estimations for the construction are run by attracting the body of mathematics of finite elements.

Key words: pre-stressed iron concrete, reactor body of nuclear power plants, high pressures, protecting envelope, concrete reduction, high pressure capacity.





UNIFIED EQUATION OF CONDITION OF ELECTRICAL POWER SYSTEMS

N.TURKIA

Unified approach to estimation of active target parameters in symmetric systems of electrical regimes (emergency and regular), which may be used in a chart of complicated configuration replacement in arbitrary reflection of metrics is presented. General equations reflecting conditions of the power system are obtained by means of modelling. In addition, the obtained regime should be identical to the initial one, i.e. all private cases can be described with these equations taking into the account an additional (characteristic for the private case) condition.

Unified equations tie together four basic parameters: nodes, nodal voltage in branches of electromotive force and currents run into branches. Unknown and free equation members are specified in compliance with the problem set. For estimating the parameters of regular regime, free members in the obtained equations would be nodal currents and electromotive force in branches and sought unknown ones would be nodal voltages and currents in branches. In emergency regimes, free members would be nodal voltages and currents in branches of the initial regime and unknown ones would be nodal currents and electromotive force in branches.