The paper presents a method for evaluation of risk changes in power system break-down origin with the help of monitoring parameters of power system operation. Quantitative evaluation has been executed on the basis of 17 power system indices and it has been shown that risk value of break-down origin is fluctuating close to a mean value in spite of increases in power station and substation equipment wear and break-down portion due to its ageing.

The paper considers an evaluation and justification of power saving efficiency and potential due to installation of power saving electric devices in the housing sector with due account of functioning of market conditions. A number of nomographs have been developed on the basis of modern methods for efficiency evaluation and technical and economical model that make it possible to evaluate efficiency of power-saving equipment. On the one side these nomographs take into account power consumption, service life and mode of electric device operation and on the other side they also take account of equipment and electric power price and bank rate. Evaluation of economically justified potential of power saving has been carried out on the basis of these models.

Problems pertaining to higher efficiency of power transformer usage at industrial enterprises and application of automatic control systems at transformer sub-stations are considered in the paper. The paper contains a simplified function scheme of such system.

In the article problems of frequency properties research for electric drive system with direct torque control and pulse width modulator are described. The mathematical description of elevator is present. Simplified mathematical description of direct torque control - pulse width modulator electric drive system is shown. Transfer functions for torque and speed loops are determined. Logarithmic frequency characteristics are computed. Damping properties of elevator drive system are estimated.

A numerical analysis of the temperature field which is cooled according to analytical and numerical schemes is given in the paper. The paper shows that an implicit scheme is closer to an analytical solution.

An equation pertaining to dynamics of automatic control of «gas-burning device - high-temperature zone» object has been formulated in the paper. The equation may serve as a basis for development of automatic control scheme.

 

Systems of from thermal power stations are considered as priority ones in the Republic of Belarus. Changes in heat load structure and operational regimes of centralized heat-supply systems have necessitated an introduction of the regimes concerning qualitative-quantitative regulation of heating load from a thermal power station.

The paper gives an approximate method for calculation of the temperature at a final stage of fuel-air mixture burning in a closed vessel that is a combustion chamber of the internal combustion engine (ICE). The paper contains calculation of temperature values for various fuel-air mixtures, shows nature of temperature changes and presents analysis of combustion product temperature behaviour modification and analyzed the behaviour in accordance with an initial pressure in the chamber. The paper reveals the fact that a combustion temperature is increasing for all mixtures when an initial pressure in combustion chamber is increased. The hydrogen-air mixture has the highest combustion temperature among investigated mixtures and products of propane conversion have the lowest one.

The Maxe-effect has been investigated in combustion of hydrogen-air mixture and design formulaes have been obtained. Calculation of temperature difference of the first and last portions of combustion products has been made with due account of the Maxe-effect.

The proposed approximate method for calculation of temperatures indices in the various zones of combustion chamber in view of the Mach effect makes it possible to forecast thermodynamic nature of combustion process while using alternative engine fuels for internal combustion engine.

The paper proposes a generalized criterion of data flow during fragmentary control over power block operation with the purpose to evaluate optimum body of the data which is presented to a power block operator. The criterion allows to minimize fuel losses while operating main equipment of a thermal power station.

The paper shows basic advantages of combined power - technological units.

The basis of power - technological units is in combining thermo - dynamical cycle of thermal and cooling expansion machines. Methodology for calculative investigations of power - technological units has been developed and presented in the paper. It is based on existing scientific developments.

The paper considers and presents methodology for obtaining analytical dependence of fuel over expenditure in respect of 250 MWT power block and regime factors of boiler unit operation while regulating t by water injection into intermediate steam - heater.

Mathematical model is proposed for efficiency evolution of the considered regulation variants where ‘integral’ fuel over expenditure is used as a criterion.

On the basis of the analysis of the literary data on heat conductivity of water solutions of salts at high temperatures, pressure and concentration the following generalizing formula is received.

On the basis of equation analysis for velocity distribution in near filter mudded zone optimal constructional parameters of sector apparatus for circulating-reagent well filter regeneration have been evaluated via angle ratio of forcing and section sectors and number of sectors. The method for determination of sector apparatus length of а selected pump that provides dissolution of mud formation in filter and near filter zone is proposed in the paper. The obtained data would promote upgrading of circulating-reagent water well regeneration technology and it permits to carry out high quality and even rehabilitation of pore space penetration along the full well filter length.