One of the causes of local overheating of submersible electric motor caused by the presence of a significant variation of electromagnetic parameters of rotor packages (RP) in the assembly of submersible electric motor is investigated in this paper. Due to the presence in the assembly of RPs with an active resistance much lower than the average resistance of the assembly, the electrical losses in RPs with resistance higher than the average increase, respectively, their heat generation increases. With the help of statistical analysis methods, the distribution of electromagnetic parameters as a two-dimensional random variable was investigated, the "convolution" of the two-dimensional distribution law was constructed. The analysis of the "convolution" of the two-dimensional law of distribution of electromagnetic parameters of the RP showed that there is a high probability of a significant scatter of parameters of the RP in the assembly.

Keywords: submersible electrical motor, rotor package, statistical analysis, local overheating, interrepair period

In this paper, based on Russian and foreign experience in mathematical modeling of photovoltaic installations, the authors consider the approaches to the construction of these models. The relevance of the research is confirmed by the wide spread of electric energy sources using solar energy. The scheme of photovoltaic element substitution and the dependences describing the processes occurring in it are given. The authors conclude that despite the large number of various mathematical models of photovoltaic elements, all of them can be grouped into two categories. The first category includes models that consider photovoltaic panels as a separate element, and the second category includes models where the photovoltaic panel is a component of a generating complex. Despite the difference in the analyzed approaches, the authors single out a number of parameters that characterize the operation of a photovoltaic panel and are sufficient to obtain simulation results with the required accuracy.

Keywords: photovoltaic panel, mathematical modeling, substitution scheme, distributed generation, power generation

The article studies the subject of human settlements with decentralized power supply, included into a locally isolated power supply complex. The basic integrated measures were determined for settlements power lines daily load curves. The results are presented, for dependency assessment between the integrated measures for daily load curves and the number of the settlement’s inhabitants. The dependency has been proven to be effectively described by a second order equation. For the dependency, the correlation coefficient, the determination coefficient and the average approximation error have been given.

Keywords: Power line load curve, decentralized power supply zone, locally isolated power supply complex, approximation