Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Vladimir N. GORYUNOV"

Development of conductive parts power losses calculation method in case of interharmonics DOI:10.15199/48.2017.06.33

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Introduction The in force guideline defining the proper quality requirements for electrical energy in a number of European countries (France, Germany, Great Britain, Poland etc.) is Standard EN 50160:2010 «Voltage characteristics of electricity supplied by public distribution networks». This standard high lights one of the possible types of excessive voltage waveform distortion, that is interharmonics. Interharmonicis «a sinusoidal voltage with frequency between the harmonics, i.e. the frequency is not an integer multiple of the fundamental» [1]. If to consider the effective standards throughout the world, the absence of any common approaches and considerable differences is obvious. In the European Union standards process in the field of interharmonics is currently at the stage of knowledge accretion and discussion. For instance, according to Standard IEC 61000-4-7:2002 [2] interharmonic voltage is limited to 0.2%. Standard EE Std 519 [3], being applicable in the USA, defines threshold values of interharmonics in low voltage (up to 1kV), medium voltage (69-161 kV) and high voltage (more than 161 KV) systems. One of the factors for the occurrence of interharmonics is «the asynchronous switching (i.e. not synchronized with the power system frequency) of semiconductor devices in static converters» [4]. Rapid changes of current in the equipment can also result in voltage fluctuations. The sources of interharmonics in power supply systems are arc furnaces, variable frequency drives, frequency converters, etc. [4]. Interharmonics have a negative effect on power supply systems operation. Depending on the interharmonics current amplitude the voltage distortions occur in the load buses at a given frequency. Depending on the interharmonics frequency bandwidth the probability of resonance increases leading to even more significant voltage distortion, to conductive parts overload and complete disturban[...]

The grid element temperature considering when selecting measures to reduce energy losses on the example of reactive power compensation DOI:10.15199/48.2018.08.24

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One of the effective directions of energy savings is the reduction of energy losses in grids and increase the transmission capacity of lines [1-2]. There is a standard set of measures to reduce losses. Selecting measures from the set in general includes two stages: - calculation of optimal exposure (appropriate way of introducing measures); - feasibility study (the payback period determination). Refinement of calculations on each step increases the measures introduction efficiency to reduce losses. In its turn, the accuracy is determined with the accepted model of the power supply mode. We consider the most important parameters that are changed with the introduction of measures to reduce losses [3]. Such parameters include the temperature resistance dependence of the grid active elements [4-7]. We present below specific examples that analyzed the influence of the temperature resistance dependence on the results of the measures selection to reduce losses and the expediency of the parameter consideration. In this case, we determined reactive power compensation as test measures, since, on the one hand, it is the most efficient and widespread measure to reduce energy losses, increase the voltage in the grids and [8-10], on the other hand, when there is reactive power compensation fully reported, both stages of selection are presented.. The calculation of the optimal exposure Economically justified selection of reactive power sources in the grid is always an optimization problem. The objective function, in general, is a criterion of economic efficiency, more often they are reduced costs; in particular cases, we can use power losses or active power losses instead of the reduced costs. Optimization problem is solved in different ways depending on the rated voltage, the grid configuration and types of compensating devices used. The article deals with the problem of choosing the static capacitor bank (BSC) in the node of non-bran[...]

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