The article describes the implementation of the principle of overcurrent protection from interphase  short-circuits  on  the  power  lines  with  unilateral  feed.  The  expression  of  the detection of the fault location by the relative value of the distance from the installation of pro- tection to the point of damage with the help of the results of operational control of the short- circuit current damaged phases has been suggested in the article. Also the expression for determining  the  time  delay response  for  such  protection  has been  presented,  taking  into account fault location that had been detected.

The paper proposes and describes the functional diagram of the overcurrent protection in detail, provides realization of the implementation of the principles set out in the article. Paper content includes the description of the elements of the considered overcurrent protection, such as input current transducers connected to the measuring current transformers of the protected line, maxiselector, miniselector, block of the determination of the mode type, the measuring unit with the setting unit, detecting fault location unit with the setting unit, calculation unit and control unit with time delay parameter setting, an OR gate, the actuating element, that opens circuit breaker of the protected line. The operation of the proposed scheme is reviewed in  the  article.  All  units  and  elements  of functional  circuit overcurrent protection  can  be implemented with the help of analog and digital technology. Modern microprocessors can be used for these purposes.

The efficiency of provided implementation of the principles of overcurrent protection from phase-to-phase short circuits on the power lines with unilateral feed was studied by computational experiments. These results confirm the effectiveness of the proposed solutions and also trip of short-circuit within the main zone line protection is provided without delay, and in the end zone redundancy – with time delay that is not exceeding 2Δt in all  areas, including the head portion of the network.

This article describes the parameters calculation for the three-phase two-winding power transformer model taken from the SimPowerSystems library, which is the part of the MatLab- Simulink environment. Presented methodology is based on the power transformer nameplate data usage. Particular attention is paid to the power transformer magnetization curve para- meters  calculation.  The  methodology  of  the  three-phase  two-winding  power  transformer model parameters calculation considering the magnetization curve nonlinearity isn’t presented in Russian-and English-language sources. Power transformers demo models described in the SimPowerSystems user’s guide have already calculated parameters, but without reference to the sources of their determination. A power transformer is a nonlinear element of the power system, that’s why for its performance analysis in different modes of operation is necessary to have the magnetization curve parameters.

The process analysis during no-load energizing of the power transformer is of special interest. This regime is accompanied by the inrush current on the supply side of the power transformer, which is several times larger than the transformer rated current. Sharp rising of the magnetizing current is explained by the magnetic core saturation. Therefore, magnetiza- tion characteristic accounting during transformer no-load energizing modeling is a mandatory requirement. Article authors attempt to put all calculating formulas in a more convenient form and validate the power transformer nonlinear magnetization characteristics parameters calcu- lation. Inrush current oscillograms obtained during the simulation experiment confirmed the adequacy of the calculated model parameters.

The importance of multi motors electrical traction drive dynamic analysis is denoted by its large application in electrical driving railway vehicles. In this paper an analysis is presented for two inducton motors traction drive with frequency inverter, vector control, and speed sensors of each electrical drive. The goal of this work is the analysis of two induction motors electrical drive, taking into account parametric perturbations and also a limited moment of wheel-rail adhesion, by laboratory study and simulation. Because of difference between motor’s parameters, it is necessary for parallel work to select motors with identical resistances and inductive winding. For this purpose the parametric identification method was used for each electrical drive, and also for two parallel motors. The result of identification was used in control setting.

The  slippage  of  the  traction  drives  is  difficult  to  reproduce  in  laboratory;  therefore a mathematical modeling and simulation of mechanical part with a traction force restriction, specific for railway transport, were carried out. The suggested simulation is built with account of elastic deformations in kinetic chain, transforming traction force. The model permits to study a dynamic system in various circumstances.

The results of laboratory investigations and simulation of dynamic regimes for two motor electrical drives are presented in this article. The results of analysis show, that a minimal difference between any parameters of two motors, parallel connected to convertor, is important for the slippage stability.

In the article the results of a wind parameters analysis at the wind power parks construction territory in the north of the Azerbaijan Republic are presented. By means of extrapolation the  speeds  of  a  wind  stream  at  heights  of  80  and  100  m  have  been  calculated.  In  the conditions  of the  Azerbaijan  Republic  initially the  wind  potential  was  defined  at  height of 10–15 m from the earth surface by the data of the “weather vane” established at hydrome- teorological station, located within the precincts of Baku city. The subsequent measurements were spent at height of 40 m by means of “anemometer” located outside of city boundaries in a southern direction. It is established that at height of 100 m the wind speed essentially ex- ceeds the wind speed at height of 22 m. Hence, the height of 100 m is profitable for construc- tion and operation of wind constructions. Results of actual measurements have shown that wind speed depends on height and time of day. It is established that change of a wind stream within a month corresponds to change of the daily schedule of power station capacity and correlation factor of two processes appears high enough and makes 0.61. Note that for building the park of wind power plant it is necessary within 1 year continuously to spend actual meas- urements of a wind parameters at various heights (to 100 m). Otherwise placing of wind sta- tion on the given site can be not profitable. It is necessary to notice that the efficiency of wind units, besides their constructive features also depends on a correct choice of their installation place.

On the other hand, the transmission of energy, produced by the wind power plants, in the power supply systems to the consumer is closely connected with a wind speed, air density, distribution of a wind stream, etc. parameters. From the told follows that research of a wind parameters represents the economic and somewhat legal value.

The article presents modeling for investigation of aerodynamic processes on area sections (including a group of complex constructional works for different regimes of drop and wind streams  and  temperature  conditions)  and  in  complex  constructional  works  (for  different regimes of heating and ventilation). There were developed different programs for innovation problems solution in the field of heat and mass exchange in three-dimensional space of pres- sures-speeds-temperatures of оbjects.

The field of uses of pneumobasic objects: construction and roof of tennis courts, hockey pitches, swimming pools , and also exhibitions’ buildings, circus buildings, cafes, aqua parks, studios, mobile objects of medical purposes, hangars, garages, construction sites, service sta- tions and etc. Advantages of such objects are the possibility and simplicity of multiple instal- lation and demolition works. Their large-scale implementation is determined by temperature- moisture conditions under the shells.

Analytical and calculating researches, real researches of thermodynamic parameters of heat and mass exchange, multifactorial processes of air in pneumobasic objects, their shells in a wide range of climatic parameters of air (January – December) in the Republic of Belarus, in many geographical latitudes of many countries have shown that the limit of the possibility of optimizing wind loads, heat flow, acoustic effects is infinite (sports, residential, industrial, warehouse, the military-technical units (tanks, airplanes, etc.)). In modeling of convective flows in pneumobasic objects (part 1) there are processes with higher dynamic parameters of the air flow for the characteristic pneumobasic object, carried out the calculation of the velocity field, temperature, pressure at the speed of access of air through the inflow holes up to 5 m/sec at the moments of times (20, 100, 200, 400 sec). The calculation was performed using the developed mathematical model of convection processes, heat and mass exchange in unlimited space based on the laws of momentum conservation, continuity, thermal conduc- tivity and the boundary conditions for pneumobasic objects which allow analyze, calculate thermal, convection streams in three-dimensional space (part 1 (2014,No4)).

Differential approximation is derived from radiation transfer equation by averaging over the solid angle. It is one of the more effective methods for engineering calculations of radia- tive heat transfer in complex three-dimensional thermal power systems with selective and scattering media. The new method for improvement of accuracy of the differential approximation based on using of auto-adaptable boundary conditions is introduced in the paper. The  efficiency  of  the  named  method  is  proved  for  the  test  2D-systems.  Self-consistent auto-adaptable boundary conditions taking into consideration the nonorthogonal component of the incident to the boundary radiation flux are formulated. It is demonstrated that taking in- to consideration of the non- orthogonal incident flux in multi-dimensional systems, such as furnaces, boilers, combustion chambers improves the accuracy of the radiant flux simulations and to more extend in the zones adjacent to the edges of the chamber.

Test simulations utilizing the differential approximation method with traditional boundary conditions, new self-consistent boundary conditions and “precise” discrete ordinates method were performed. The mean square errors of the resulting radiative fluxes calculated along the boundary of rectangular and triangular test areas were decreased 1.5–2 times by using auto- adaptable boundary conditions. Radiation flux gaps in the corner points of non-symmetric sys- tems are revealed by using auto-adaptable boundary conditions which can not be obtained by using the conventional boundary conditions.

The usage of digital micro-processing automatic means allow to use design methods (technique) of automatic control systems  more wider, and also to apply optimal ways of control, for example, it is possible to combine the Method of structural-parameter optimization and invariance theory. This method allow to increase essential system speed in processing of task jump and to reduce operation time of outside external disturbance up to two  values of regulated influence, and the usage of invariance principle is based on an additional measuring of the most dangerous perturbation influence and in connection with it the improvement of regulation quality is achieved.

In this article the principle of invariance is applied in order to improve greatly external disturbance attack by consumption of over-heated steam. Compensation of disturbance influence on regulated value is achieving by introduction of additional signal on input of correction regulator from output of compensation device, measuring the external disturbance by consumption of over-heated steam.

Modeling results of transient processes of cascade system of automatic control (CSAC), on the base of which were realized the unity of these methods, demonstrated the fact that, in processing of external disturbance by consumption of steam, the reduction of maximal dynamic regulation error is six times and cutting of regulation time by 30 % in comparison with CSAC without compensation device of external disturbance. And that is why it leads to the further reduction of maximal dynamic regulation error in processing of external disturbance by consumption of steam, and this allows to improve the quality of control.

The article shows the calculation comparison of fuel for producing of heat-line water with a help of different technological installations, transforming (converting) high-grade heat from burning process of fuel or in the process of non-reversible heat exchange with coolant (heating agent), or with a help of heat engines, which allow to decrease losses of working efficiency and thus to reduce the use of fuel. There were considered five types of plants beginning from the  simplest  one  up  to  the  most  complex  in  two  variants,  when  the  heat  exchangers and machines are perfect (ideal) and when equipment has the known degree of efficiency (perfection):

1) water-heat boiler station, working on organic fuel;

2) electrical boiler station, obtaining energy on power transmission lines from condensing power station;

3) line heater of TPP, obtaining steam from heating turbine;

4) line heater CPP, powered by steam from pressure reducing unit;

5) heat pump, producing energy on power supply lines from TPP.

In this article were investigated three ideal reversible ways of transformation of   high- grade heat into low-grade heat with a help of decreasing and increasing and combined (suggested by the authors) heat transformers and their thermodynamic equivalence was shown in this article. And there were suggested universal installation for electric energy generation, cold and heat of two grades for heat-water supply and the heating process on the base of gas

compressors   gas turbines. These results are so important (actual) for power engineers of the countries with  increasing consumption  of organic  fuel and  its enhancement in  value and realizing programs of energy saving .

The analysis shows, that the quality of produced low-grade heat per unit of used high-grade heat for ideal plants (installations) is: electrical boiler unit – 0.7;  water boiler unit – 1.0; for heat pump, heating turbine, combined heat transformers   – 4.9. Increasing of quality of high-grade heat does not break the Law of Thermodynamics, just on the contrary, thank this the constant heat efficiency is remained. Conversion ratio for real variants of these plants are: 0.415; 0.9; 1.53; 2.8; 1.47. Thus, it is once more proved, that TPP is the most efficient source of heat for heating process and stands head above electrical boiler unit in 7 times, above plants with heat pumps in 2 times. Universal electric power plant is comparable in effi- ciency with heat pump system, but outperforms it due to its multi-functionality.

Reliability of continuous operation of pipelines is an actual problem. For this reason should be developed an effective warning system of the main pipelines‘  failures and accidents not only in design and operation but also in selected repair. Changing of linear, unloaded by bending position leads to the change of stress and strain state of pipelines. And besides this, the stress and strain state should be determined and controlled in the process of carrying out the repair works. The article presents mathematical model of pipeline’s section straining in viscoelastic setting taking into account soils creep and high-speed stress state of pipeline with the purpose of stresses evaluation and load-supporting capacity of repairing section of pipeline, depending on time.  Stress and strain state analysis of pipeline includes longitudinal and circular stresses calculation  with  account of axis-asymmetrical straining and  was  fulfilled  on  the base of momentless theory of shells. To prove the consistency of data there were compared the calcu- lation results and the solution results by analytical methods for different cases (long pipeline’s section strain only under influence of cross-axis action; long pipeline’s section strain under in- fluence of longitudinal stress; long pipeline’s section strain; which is on the elastic foundation, under influence of cross-axis action). Comparison results shows that the calculation error is not more than 3 %.

Analysis of stress-strain state change of pipeline’s section was carried out with development  of  this  model,  which  indicates  the  enlargement  of  span  deflection  in  comparison with problem’s solution in elastic approach. It is also proved, that for consistent assessment of pipeline maintenance conditions, it is necessary to consider the areolas of rheological processes of soils. On the base of complex analysis of pipelines there were determined stresses and time-deflection relation for two types of soils with different rheological properties.