No 2 (2024)

The article presents the main components of the methodological approach to the analysis of the possibilities of supplying final types of energy to consumers in the event of a loss of performance of critical facilities of the Russian gas industry in conditions of cooling in the territories of the federal districts. The principle of choosing a territorial section for analyzing the situation with a simultaneous increase in demand for fuel and energy resources is described. An algorithm for conducting research is given. Research is carried out by modeling the work of the country’s fuel and energy complex during the period of the average day of January in the conditions of a peak-increasing demand for thermal energy in the territories of federal districts. At the same time, the cooling is modeled in turn for each of the federal districts in the zone of operation of the Unified Gas Supply System of Russia. An analysis of the possibilities of meeting the demand for final types of energy in the constituent entities of the Russian Federation is carried out for all key scenarios of cooling and loss of efficiency of critical gas industry facilities. The principles of modeling the situation with the supply of final types of energy to consumers in these situations are shown. The most vulnerable regions under the analyzed conditions are identified. The conclusion is made about the need for a balanced approach to determining the optimal degree of dominance of natural gas in the fuel and energy balance of the regions, taking into account the existing opportunities for its supply in the conditions of large-scale emergencies in the gas industry.

Dependence of the CPU time needs for calculation of the source term during a severe accident at nuclear power plants with WWER reactors from the individual physical processes and phenomena used as part of the calculation tools similar to the SOСRAT/V3 severe accident code is investigated. This analysis allows revealing the most expensive models in terms of runtime. The simplification of these models can ensure the greatest acceleration of the calculation. The relevance of the task draws from the need to develop new or adapt existing calculation tools for assessing the intensity of radioactive emission sources for the tasks of emergency preparedness and response considering the specific requirements for the accuracy of numerical estimates and time to obtain them. The paper demonstrates the possibility of reducing CPU time without significant loss of accuracy of the numerical estimates by simplifying the spectrum of aerosols sizes. The efficiency of the proposed approach is demonstrated by the example of modeling the Phebus FPT1 experiment.

An increase in the penetration level of power plants based on renewable energy sources using power converters (PCs) has a direct impact on the dynamic characteristics of modern electric power system (EPS) and, as a consequence, the nature of the transient processes. One of the main problems in such EPS is a significant change in the magnitude of the total inertia of the system over time, which leads to an increase in the rate of change of frequency and the magnitude of its maximum deviation under various disturbances. A promising direction for solving this problem is the synthesis of new structures of PC control systems based on a virtual synchronous generator (VSG) with adaptively changing parameters. The results of the research in this area are presented in the paper, which consists of two parts. In the first part of the paper, the dependence of the adaptive algorithms efficiency for controlling the parameters of the VSG on the structure used is substantiated. A comparative analysis of the developed modified VSG structure with traditional algorithms is performed and its fundamental advantages are proved. The second part of the article presents an analysis of the influence of the modified structure parameters of the VSG on the dynamic response using time domain transient analysis. Based on the results obtained, adaptive algorithms for independent control of virtual inertia and parameters of the VSG damper winding have been developed. The performed mathematical modeling confirmed the reliable and efficient operation of the developed adaptive control algorithms and the modified structure of the VSG as a whole. From the theoretical and experimental results obtained in the paper, it follows that there is a need for simultaneous development and improvement of adaptive control algorithms and the VSG structures used for this.

The problem of monitoring the parameters of nonlinear elements included in various electrical devices is considered. A new algorithm for reproducing the nonlinear current-voltage characteristic of a device based on the measurement results has been proposed and investigated, which has several advantages over the known ones, allowing, in particular, to obtain an analytical representation of the current-voltage characteristic in real time. The proposed algorithm is based on the direct determination of the coefficients of the polynomial approximation of the current-voltage characteristic. A review of scientific research done to date by other authors dealing with this problem has also been carried out. Formulas for determining the amplitudes of current harmonics through power series coefficients and voltage amplitudes on a nonlinear element are obtained. Binomial coefficients are used to facilitate intermediate calculations. The relations for the zero, odd and even harmonics of the current are obtained, as well as analytical expressions for the coefficients of the polynomial approximation. An experimental study of the proposed method was carried out, according to the results of which an assessment of its accuracy was made. The use of the proposed method significantly simplifies the processing and reduces the measurement time of nonlinear VAC.