The factors determining the need for modernization of urban district heating systems with combined heat and power are considered. It is noted that these factors include a significant reduction in thermal loads, new technical and technological opportunities for improving district heating systems, the change in legislation in the field of energy and heat supplying. It is shown that the main disadvantage of the current state of Russian cogeneration systems is a decrease in the combined production of heat and power, leading to a decrease in the efficiency of fuel use, due to unreasonably extensive use of autonomous heat supply sources in many regions. Besides, combined heat and power plants (CHPP) experience a lack of a level playing field in competition with other power plants in the electricity market, with a technically and economically unjustified ban imposed on open heat supply systems. For effective use of the benefits of cogeneration and district heating, the following top priority measures are recommended. It is required to legislate the economic benefits for the combined production of electricity and heat. It is necessary to adjust the model of the wholesale electric energy and power market to eliminate discrimination of CHPP in this market. The construction of autonomous heat sources in urban areas with CHPPs is to be prohibited unless substantiated with an adequate feasibility study. Decommissioning of CHPPs and heat sources, which are used to back up CHPPs, must only be permitted subject to a mandatory feasibility study, including assessment of effects on reliability of heat supply of urban consumers. The Russian Federal Law “On heat supply” is to be adjusted to lift the total ban on the use of open heat supply systems. It is required to create a national body with sufficient authority to control and coordinate the activities of energy companies to modernize cogeneration and district heating systems.

In part 2 of the paper, technical and economic necessity is substantiated of commissioning of the second circuit of 500 kV “Rostov NPP-Shakhty” (without extending the same to substation 500 kV Rostovskaya) and construction of OHPL 500 kV from substation Rostovskaya to substation Taman. This will enable to increase the supply of power to the Crimean “energy bridge” to transmit the same to the Crimean energy system up to 800–850 MW and to raise the probability of failsafe operation of the basic network to 0.986, i.e., reduce the time of emergency conditions of basic networks to 130 hrs/year, improving the reliability level of the network, which existed before the connection of the Crimean energy system.

Further social and economic development of tourist and resort areas of Krasnodar Territory and Crimea can ensure, with proper stimulating economic conditions, a growth of power consumption and loads of Krasnodar Territory and Crimea with a factor of 1.5–2, particularly in summer. Therefore, it is necessary to explore the technical and economic feasibility of two options of construction in Krasnodar Territory or in Crimea of a new power plant with a capacity of up to 1000 MW and reconstruction of the Crimean energy bridge for transmission of direct current. This will double the throughput of the “energy bridge” to the capacity of nearly 2 million kW, which, combined with further development of power-generating facilities of the Crimean energy system, will enable to supply the Trans-Dniester and the Bug areas with electric energy, if necessary.

In case of switching the Crimean “energy bridge” to direct current, with a capacity of up to 2 mln kW to be transmitted through this bridge, it will be necessary to strengthen electric links, with these to be switched to the voltage 500 kV between substation Kafa (the point of connection of the “energy bridge” to the Crimean energy system), Simferopol and Sevastopol.

This matter is supposed to be considered in subsequent studies of reliability of power supply of Crimea.

The article is devoted to choosing ways to improve the technological reliability of regional electric network (REN) to ensure reliable power supply. At the operational stage, the task of increasing operational reliability is assigned to the enterprise asset management system of the territorial network organization (TNO), as a REN operator. Technological reliability is ensured by an operational dispatch control system, which uses the existing reserves in the network to support the technological process of electricity supply to electricity consumers in case of network equipment failures. The relevance of improving the technological and operational reliability of power supply system (PSS) requires the development and improvement of methods for analyzing and assessing the TNO's readiness to provide power transmission services. The indicators adopted in Russia reflect the level of technological reliability of PSS. However, these indicators do not reflect the technical condition of the equipment, or identify causal relationship between an equipment failure and an interruption of power supply. The research is aimed at identifying “bottlenecks” from the technological reliability standpoint and substantiating maintenance and repair, and technical re-equipment and reconstruction measures to improve operational reliability. A PSS model is proposed reflecting the technical condition of the network equipment, the operational readiness of automation systems, the availability of structural, functional and load redundancy in the REN. A method is suggested for calculating the PSS reliability indicators, where the developed indices reflect the degree of development of the network technical potential and the role of the aforesaid nodes in the PSS. The method makes it possible to identify the network parts, where it is necessary to introduce new technologies. In contrast to a well-known method, which is based on expert estimates of probabilities of different circuit-mode states of the network and on the calculation of normal and post-emergency modes, a less timeconsuming formalized procedure for analyzing and evaluating the network structural and functional reliability is proposed. The results obtained allow to increase the validity of the decisions made both at the operational stage and the design stage.

The article is dedicated to the study of the problem of the influence of climate change on the reliability and safety of the power complex of the Moscow metropolis. The analysis of climatic change in the Moscow region shows the number of dangerous climatic events that have intensified over the past ten years, leading to economic damage. In the paper, the observed manifestations of climate change have been analyzed, isolated and ranked according to the effect on the reliability of the power supply system. The vulnerability of the electric power industry to unfavorable climatic events is considered. The analysis is presented of accident rate, economic damage in some basic elements of the power system.

The power supply system of the Moscow energy center is characterized by high reliability and saturation with devices for converting, distributing and transmitting electrical energy. Based on the official statistics of local power outages in the Moscow metropolis, analysis is performed of the intensity of failures of overhead power transmission lines. Correlation analysis of their interrelation with the intensity of occurrence of dangerous climatic events is performed. It is shown that the most intensive effects are not only produced by individual climatic events, but also by some of their combinations: "strong wind" and "ice"; "high humidity" and "a high number of temperature transitions through 0 °C", etc. Based on the dependencies obtained, regularities have been revealed that allow predicting the key parameters of damage from the most frequent unfavorable climatic events, which have become more frequent with climate change. Through the application of regression methods of analysis, the functions of the dependence of the occurrence of wire breaks in high-voltage distribution networks with a voltage up to 110 kV and wire breaks in backbone networks with a voltage over 110 kV on climatic factors are substantiated.

An estimation of the total economic damage to the power grid complex in Moscow from the most influential climatic events has been performed. Some low-cost oportunities for adaptation of existing power transmission networks to the change in the Moscow metropolis are considered.

For selecting optimal regimes and design characteristics, an energy efficiency criterion of a mass transfer apparatus is considered, and on its basis, some particular cases of energy efficiency criteria for cooling towers, including the cases with a structured counter-current film-type packing, are obtained. The criteria include heat transfer efficiency in the gas and liquid phases, as well as kinetic characteristics of the process of cooling the water in blocks of film-type packings. Expressions are given for determination of thermal efficiencies in the gas (air) and liquid (water) phases of the cooling tower. Three notations for the energy efficiency criterion of cooling towers are obtained. In the first notation, the efficiency criterion is written down using the thermal efficiency of cooling the water; in the second notation, it is written down using the thermal efficiency of heating the air; in the third notation, it is written down via the transfer coefficient (mass transfer) and mean driving force in the form of an enthalpy difference. A notation of writing down the energy efficiency criterion for a film-type packing in the cooling tower with a volumetric mass transfer coefficient is presented. Irrigator blocks filled with structured film-type contact devices of various designs having an irrigation density of 12 m³/m²h and an air speed of 1.5 m/s are considered. Results of calculations of five types of structured packings are presented: tubular packing made of polyethylene net; metal packings VACU-PAK, PIRAPAK G, “Inzhekhim” IRG and segmentary-structured packing “Inzhekhim”. Values are obtained of the criterion of energy efficiency of these packings for cooling the water as well as the required height of irrigator blocks for a given temperature regime and hydraulic load. Values of the power expended for supplying the air to the irrigator blocks are determined and a histogram is plotted. It is concluded that modern domestic and foreign metal packings have high thermal and hydraulic efficiency and are recommended for use in mini-cooling towers (except for tubular packings made of polyethylene net). For reducing the cost of irrigator blocks, these can be made of polymer materials. Then such blocks of irrigators are recommended for creating a contact between the phases in large-scale cooling towers, which will significantly improve the efficiency of cooling the water at thermal power plants and industrial enterprises.

Accidents in power transmission lines under icing conditions, in particular, those of cables, cause a great economic damage in Russia. Because of the lack of the possibility to forecast and evaluate reliably the consequences of weather conditions contributing to icing of transmisison line cables, power grid services often have to go to the place of a potential accident relying on guesswork. This leads to considerable losses of time and material resources, while the average recovery time of a damaged high voltage power transmission line is 5–10 days.

For the effective prediction and timely prevention of negative consequences of icing of on power line cables, an analytical model that describes the growth of ice on the surface of the electrical cable has been developed. The model is based on a widely applicable analytical model of [1], supplemented with dependence of the growth of ice sleeve on the angle between the wind direction and the cable, and on the electric field strength of the cable.

The results obtained using the new analytical model and the [1], model have been compared and show that as the angle between the wind direction and the cable decreases, the intensity of the ice growth decreases significantly. At the same time, the strength of the electric field of the cable affects negligibly the trajectory of water droplets.

A conclusion is drawn about insignificance of electrical field strength of the electric cable as a factor of growth of ice deposits. It is stated that the ice thickness value obtained using the developed model can be increased under specific weather conditions and design parameters of transmission lines. The obtained model can be improved by using other physical effects that affect icing of electric cables. Further, the model can be introduced in operation of energy companies to monitor the condition of power transmission lines and to carry out anti-icing activities.

The questions of evaluation of energy efficiency of municipal heating and electric power supply systems based on the combined heat and power supply plant (CHPP) with a reduced temperature of return delivery water are considered in the paper. As a method of reducing the return delivery water temperature, using heat absorption transformers (HAT) at central heat supply stations operating as absorption heat-exchange facility was considered. The exergetic efficiency was chosen as an evaluation criterion, because, given the difference in kinds of energy in the system, it allows to perform both relative and absolute estimates of thermodynamic effectiveness as well as takes into account the losses from non-equilibrium of processes in the system. Results are given of HAT multiparameter analysis that were obtained on the basis of a developed mathematical model, the reliability of which was experimentally tested. During analysis of the heat supply system, one should take into account the influence of return delivery water temperature on consumption of heat-transfer agents and power consumptions on driving the recycling pumps in the heating network and pumps in the consumer network. Additional components are inntroduced into the equation for determining the exergetic efficiency of CHPP. The traditional heat supply system is compared to the central heat supply station and the new system with an absorption transformer AT (central heat supply station) for different temperatures of delivery water in the flow line. The relative correspondence method proposed by V. P. Motulevich was used for the comparative analysis. The results are analyzed by the following lines of the heat supply system: Source-AT (central heat supply station), SourceConsumer. In the Source-Consumer line, a considerable increase is shown of exergetic efficiency in the new system at a rather high temperature of delivery water in the flow line. This is due to variation of power consumption on driving the recycling pumps and the generator unit capacity gains. Turbine-generator set T-100-130TMZ is selected as a source.

The object of research is the power equipment (steam boiler, steam turbine, turbine generator, etc.) of modern heat power systems. When creating, operating and repairing expensive power equipment, one faces a relevant problem of failure prediction. To solve this problem, a task is set to develop a mathematical model of planning the scope of tests of power equipment prototypes. During the testing of test samples, the entire testing period is generally divided into a number of stages, at each of which the scope of tests is recorded, expressed in hours or cycles, depending on whether the power equipment is continuously or cyclically operating. At each stage, the number of failures is recorded, as well. After the cause of the failure is identified, the main equipment of the TPP is elaborated. The elaboration is considered effective if it is followed by the same scope of tests, with no failures recorded. Two methods for planning the scope of tests have been presented. The first method is based on double sampling, the second one — on multiple sampling. When planning the scope of tests, mathematical models of failure prediction for both double and multiple sampling have been developed on the condition of no failures, or the occurrence of no more than one failure after elaboration in a subsequent sample. The presented method is simple in practical application. In order to assess the effectiveness of the elaboration, the fitting criteria in binomial and normal laws of failure distribution have been proposed. The conducted research allows to obtain mathematical models of failure prediction during testing of prototypes  of power equipment of TPP, as well as mathematical models of the fitting criteria in binomial and normal distribution laws.

The policy of restructuring the generating capacities of the energy system of the Republic of Belarus assumes the introduction of the the Belarusian nuclear power plant (NPP) in the coming years. The presence of external and internal factors affecting the sale of electricity from NPP will require solving a number of problems, including power redundancy and frequency control through involvement of internal power generating facilities. These include steam-turbine state power plants and combined heat and power plants (CHPP), combined-cycle power units, special mobile electric power units, the commissioning of electric boilers and accumulator tanks. The latter is a new technical solution for the Belarusian energy system that requires careful analysis to identify the optimal system for coordinated operation of co-generation power units with electric boilers and accumulator tanks. At the same time, the heating and non-heating seasons of the CHPP operation are considered. The function of the accumulator tanks with minimum and maximum power consumption is shown. At charging of the accumulator tanks, the generation of electricity by co-generation power units with thermal regulation is increased. The operation of electric boilers and accumulator tanks is considered through the example of Grodno CHPP-2. The expediency of including electric boilers in the scheme of the CHPP as the most effective means of using co-generation turbine units in the cycling mode with unloading them by electric power during the night hours is determined, which ensures the maximum reduction of the electric power output to the power system from the Belarusian NPP.

A similar approach at other industrial CHPP of the power system will, to some extent, ensure stable power supply from the Belarusian NPP. Reconstruction of the CHPP with installation of accumulator tanks will make it possible to create a flexible heat supply scheme for consumers in the conditions of night electrical unloading when the NPP power units are put into operation.