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The aim of the study is to develop a methodological approach to assessing the incremental effi-ciency of electricity generation at CHPPs (specific heat consumption for changing electric power of turbine) in operating modes, taking into account both energy and environmental indicators. To achieve this goal, the following tasks were solved: the methodology, based on mathematical models of cogeneration steam turbines, both integral and differential indicators of heat rate per unit of electricity generation increment, was justified; a comprehensive generalization of the cal-culation data on the turbine T-50-12.8 type was performed; a quantitative assessment of the in-tegral electricity generation and greenhouse gas emissions parameters was made at various loads and its comparison with the corresponding indicators in condensation mode. The most signifi-cant results are the following: generalized dependences of the integral specific heat consumption per unit of increase in electricity generation and carbon footprint were calculated for a wide range of changes in operating conditions; boundary conditions were established under which obtaining these parameters by opening the sliding grid of low-pressure section turns out to be energetically and ecologically feasible; it was determined that when increasing the capacity without bypassing the delivery water, the carbon footprint increment with an increase in the ca-pacity of cogeneration turbines by opening the sliding grid will be less than for condensing tur-bines. The significance of the results obtained lies in their applicability for solving problems of ensuring maximum efficiency during involving cogeneration turbines in regulating electric load schedules in different boundary conditions.

The aim of the work is to analyze and evaluate the operating efficiency of CHPPs to develop an optimal operating strategy based on minimizing fuel consumption and greenhouse gas emissions. To achieve this goal, the following tasks were solved: a quantitative assessment of the most effective methods of operating units in typical operating modes was given; dependences of changes in the main energy and environmental parameters based on mathematical models of turbine units using real energy characteristics of turbine stages and compartments were constructed; long-term optimization method to exploitation operation of CHPРs to the point of view of reduc-ing greenhouse gas emissions was shown on specific examples. The most significant results are the following: a comprehensive methodology for applying mathematical models for solving the most typical problems for CHPP was used, both from the point of view of saving primary fuel and reducing carbon emissions; the dependences of the influence of operating parameters on the carbon footprint were calculated; it has been established that the specific consumption of equiv-alent fuel and the carbon footprint are reduced when the loads are redistributed between turbine units during the heating period; the advantages of two-stage heating of delivery water over single-stage heating and sequential loading of turbines of the same type over parallel loading have been determined. The significance of the results obtained lies in their applicability in solving problems of optimizing the operating modes of CHPPs, taking into account the determination of the values of reducing greenhouse gas emissions.

The aim of the work is to study the efficiency of steam turbine CHPPs in heat-supply systems, taking into account changes in the temperature of delivery water during transportation for vari-ous initial and extended heating regulation schedules. To achieve this goal, the following tasks were solved: calculation of the dependences of the delivery water cooling in the supply and re-turn pipelines on the air temperature, construction of temperature and flow rate schedules of de-livery water adjusted for heat losses during transportation, calculation of energy efficiency indi-cators for the operation of a model CHPP with various options for correcting schedules of deliv-ery water. The most significant results are the following. Firstly, for the first time the method of the degree-by-degree calculation of heat losses during transportation and their distribution be-tween pipelines of heating networks was used. Secondly, the dependences of the delivery water cooling in these pipelines on the outside air temperature are calculated. Thirdly, it has been es-tablished that the specific reference fuel consumption for electricity supply significantly de-creases when switching to more efficient temperature schedules for heating regulation, but changes slightly when switching from natural regulation by flow rate to regulation by the tem-perature of the delivery water. The significance of the obtained results lies in the possibility of their use for an accurate assessment of the efficiency of heat supply systems with different heat-ing control schedules and for determining the feasibility of correcting temperature schedules in order to take into account the cooling of delivery water during transportation.

The aim of the work is a theoretical study of the efficiency of heat supply based on a software package that includes mathematical models of a real CHPP, a real heating network and real heat consumers with a high share of hot water supply load using extended and reduced temperature schedules of heating regulation. The set aim is achieved by solving the following problems: choosing a method for calculating various schedules of regulating heat supply from CHPPs; con-struction of initial, reduced and extended temperature schedules and schedules of delivery water consumption; determination of optimal energy costs and heat-transfer agent costs. The most im-portant of the results achieved is the carried analysis of the energy and economic efficiency in-dicators changes during the transition from the traditional to lowered and extended schedules of heat-supply system regulation. The total fuel savings at CHPP during the transition from the ini-tial design temperature schedule with a maximum delivery water temperature of 150°C to the most energy efficient schedules reaches about 2%, which should be recognized as very signifi-cant. The significance of the obtained results lies in the fact that they allow calculating the ener-gy effect in the form of fuel savings at CHPPs compared to their operation with the design tem-perature schedule. It is shown that the use of these technologies will increase the efficiency of district heating that will ensure a reliable and high-quality supply of heat energy to consumers and reduce its cost.

The aim of the work is a computational study of the effectiveness of the extended schedules of heating regulation at steam turbine CHPPs with a decrease in the normative design temperature of the supply water. The study was carried out on adequate mathematical models of CHP tur-bines and heat supply systems, considering heat pipelines' actual diameters and lengths. The main energy efficiency indicator is the specific reference fuel consumption for electricity sup-ply, calculated under comparable conditions for the operating modes of turbine plants and the load of the heat supply system. The study took into account the electricity consumption for the drive of network pumps, standard heat losses in heating networks and the electricity generation for the heat consumption of CHPPs. The study results allowed for the first time to determine the integral indicators of the energy efficiency of work during the transition of CHPPs from the normative design ones to the temperature schedules reduced by the temperature of the supply water. At the same time, the calculations revealed the limitations on the parameters of the extended schedules of regulation when transitioning to reduced temperature schedules. The most important results of the work should also be attributed to the determination of the optimal schedules of the temperature of the supply water for different values of the district heating coef-ficient of the CHPP. The results obtained are essential for assessing the efficiency of the transi-tion of heat supply systems to reduced supply water's design temperatures when using modern heating regulation schedules.

The aim of the work is to study the energy efficiency of using an extended schedule of heating regulation when using it for a model district heating system connected to the CHP. The extended schedule of heating regulation ensures the maximum use of the thermal potential of the heat transfer agent and the minimum energy costs for its transport. The assessment of the impact of the extended schedule on the energy efficiency of the CHPP operation was carried out by using an adequate mathematical model of the heat supply system in a generalized form. It was deter-mined that when switching to an extended schedule, the specific energy production for heat consumption in a wide range of changes in the district heating coefficient of a model CHPP in-creases by 1-2% when working on an electrical schedule and by 4-6% when working on a ther-mal schedule. The calculation of the modes of a model CHPP with a fixed design heat load of the CHPP and constant electric power showed that the transition to an extended schedule leads to fuel savings of up to 4.5% during the heating period. Calculations showed that a decrease in heat supply during the transition to new methods of regulation is unprofitable for thermal power plants; therefore, tariffing in the field of thermal energy requires changes, including the transi-tion to two-part tariffs.The results obtained are important for assessing the effectiveness of the transition of heat supply systems to modern schedules of quantitative and qualitative regulation.

The paper discusses options for district heating systems, including thermal power plants and heat pumps installed in individual heating centers of multi-story buildings. The aim of the work is to evaluate the energy efficiency of the options under consideration and the method of connecting piping to high-temperature return network water with a carbon dioxide heat pump. The goal is achieved due to the fact that one of the evaporators of the heat pump heating the new building or half of the existing building uses heat from return network water or from the first half of the building or from the whole building, and the second evaporator uses the heat of the outdoor air. Moreover, for high-temperature heating schedules, heat is taken out through a two-stage inter-mediate circuit containing two pumps, 2 heat exchangers and two expansion vessels. Significant results of the work are the developed scheme of the intermediate circuit of the carbon dioxide heat pump, which combines both the possibilities of working in a quantitative heat supply sys-tem and in the preparation of hot water for buildings during the non-heating period. The signifi-cance of the obtained results lies in the fact that the proposed technical solution allows to reduce fuel consumption for thermal power plants, consumers' expenses when paying for their con-sumed energy resources, increase the number of heat consumers connected to the thermal power plants through the use of heat pumps. The schemes of intermediate circuits of heat pumps for the quantitative law of regulating the operation mode of the heat supply system are also consid-ered.

The purpose of the study is to determine the conditions and efficiency of the use of built-in bundles of condensers of cogeneration steam turbines for make-up water heating during their work when the main bundles are disabled. The proposed method for estimating the heat flows entering the condenser when working with a closed sliding grid is used. The program of the thermal calculation program for steam turbine condensers and a computational mathematical model of a turbine plant type T-50-130 are applied. The heat fluxes entering the condenser were calculated in a wide range of influencing factors. An important result of the calculations is the identification of significant limitations of the applicability of this method of the make-up water heating according to the condition that the temperature of the make-up water at the exit from the built-in bundle is not exceeded. Calculation studies on the mathematical model of a condenser to determine the pressure in the condenser depending on the pressure in the lower heat extraction section with different levels of throughput of the closed sliding grid and different flow rates of the make-up water were carried out. Another result is a calculated estimate of the energy efficiency when using built-in bundles for heating the make-up water. It was found that heat saving in the considered modes always takes place, and when working on a heat mode, it is close to the heat load of the built-in bundles, and when working on an electric mode, it is several times lower.

The urgency of the work is conditioned by the need to improvethe management methods of the operation modes of the power plant by creating software tools for predicting the performance of equipment when the conditions of its operation change. In this regard, the aim of the study is to carry out a detailed calculation research of such modes using uniquecomputational mathematical models based on the actual turbine power characteristics. Following tasks were set to achieve it: first, to calculate the limits of change for the main energy and economic indicators in real operating conditions on the example of the turbines T-50-130 of the Kirov CHP-4; secondly, to identify and describe the possible resources to increase the efficiency of the operation of the cogeneration turbine plants under conditions of variable heat and electric load schedules. The received results testifythat at today's prices for energy carriers, additional power generation by the thermal cycle of CHP plants is economically feasible during all day. The low economic efficiency of some common methods of generating peak power is shown, in particular, by changing the degree of opening the sliding grids in the low-pressure section. The proposed approach can be implemented and used to optimize the operation of CHP plants in the Russian wholesale electricity and capacity market. The results of the study make it possible to conclude that most steam turbine CHP plants have significant reserves for saving fuel and energy resources, which can be realizedby optimizing turbine operationmodes.