Vladimir N. Goryunov

Subject of research: methods for assessing the economic efficiency of renewable energy sources Purpose of research: describe the state of electricity production based on renewable energy sources in the world and in Russia, and provide calculations of efficiency indicators. Object of research: electrical power systems with renewable energy sources. Main results of research: an overview of the performance of power plants based on renewable energy sources around the world and an analysis of the economics of promising projects based on the use of renewable energy sources in Russia are provided. An analysis of statistical deviations over the past eight years was carried out. Object: to describe the state of electricity production based on renewable energy sources in the world and in Russia, to calculate the efficiency indicators of renewable energy sources.

High-power ore furnaces mainly use single-phase transformers supplied by phase-to-phase voltage with the secondary winding made in the form of four to eight isolated splits and a high-voltage busbar assembly made of the same number of pairs of tube buses. Due to these design features, turn-to-turn faults are the main faults in the primary winding of the transformer, and flexible coupling breaks and arc faults in splitting circuits prevail in the high-voltage system. This is why current and gas protections are currently used to protect transformers against short circuits. However, current protections are insensitive to turn faults, and the gas protection response time can be long since it strongly depends on the oil temperature. High-current systems are protected from arc faults only by insulating tube buses. However, this insulation is gradually destroyed under the impact of abrasive dust in the air, and the presence of coal dust in the air creates conditions for arc faults. There is no protection against breaks in the circuits of pairs of tube buses. The extent of damage in a transformer and its high-current system due to the faults can be significantly reduced by using new protection devices based on the measurements of the longitudinal and transverse asymmetry of the stray magnetic fields of the protected transformer. To implement these protections, this article suggests a method for protecting a transformer and a high-current system using magnetic current transformers (MCTs). The number and points for MCT winding coils are determined through the analysis of their EMF values versus their positions relative to the windings of the transformer operating under different modes. The results serve as the basis for the protection circuit design; the protection response threshold is calculated, the protection operation is described, and the results of the experiment are given.

Subject of research: optimal placement and operating modes of solar power plants, taking into account the reduction of carbon dioxide emissions. Purpose of research: determine the influence of different orientations of photovoltaic power plants on carbon dioxide emissions Object of research: photovoltaic plants Methods of research: a combination of data coverage analysis models and an analytical hierarchy process Main results of research: It is shown that vertical photovoltaic systems can reduce storage capacity or reduce the utilization rate of gas-fired power plants. Without any storage options, it is possible to reduce total carbon dioxide emissions to 10.2 million tons per year.

Rozwiązano problem optymalnego wyboru akumulatora kondensatora, biorąc pod uwagę roczny harmonogram mocy biernej w sieci. Określono wyrażenia czasu włączenia akumulatora kondensatora i strat własnych w nim. Pokazano technikę zmniejszania strat energii elektrycznej w sieci. Uzyskano wyrażenia określające optymalną moc akumulatora kondensatora w sieci, biorąc pod uwagę aktywną rezystancję sieci, na podstawie których sformułowano praktyczne zalecenia. (Optymalny dobór baterii kondensatorów statycznych i współczynnika kompensacji w zależności od rezystancji sieci)

One of the key indicators of the energy efficiency of electrical power systems should include the level of electric power losses. In a market economy, the significance of losses increases, since the cost of losses is an essential component of the tariff. One of the effective measures to reduce power network losses is reactive power compensation. However, the cost of compensating devices used for this purpose disagree with the task of reducing electric energy losses. The paper describes the effect of changing the capacity of static capacitor banks on the value of losses in the network with variation in the number of sections and the type of annual reactive load curves. The effect of the number of capacitor bank sections on the maximum reduction of annual reactive power losses in the network is analyzed. For the linearized load graphs, the relations for the values of natural losses in the capacitor banks are obtained, as well as expressions applicable to estimate the reduction of losses in the network. The conclusion is drawn that full reactive power compensation is impractical in most cases. The dependence of loss reduction on the power of capacitor banks reaches the maximum at the point where the battery power is less than the load power. It is proved that significant reduction of the loss in reactive power transmission in the electrical network requires no more than 3-4 sections (the reduction is close to 100 percent), and a 90 percent reduction in a wide range of load curves can be achieved with two sections..

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