PoweR ComPoNeNTS of eleCTRiC eNeRgy foR TeChNiCAl AND CommeRCiAl eleCTRiCiTy meTeRiNg Purpose. Determination of power components of electric energy in the circuits with polyharmonic current and voltage. methodology. Using the modern equipment for measuring the amount of electricity consumption and estimating its quality, an experimental study of the mode indicators of the electric power network node of a small enterprise with a synchronous average-size generator, with a nonlinear and non-symmetric load is performed. Based on well-known publications, the concept of determination of active and reactive power with the use of scalar and vector products of instantaneous currents and voltages is analyzed. findings. As a result of analyzing the obtained indicators, power quality defects were recorded. It was noted that measuring the amount is based on the well-known concepts of the active and reactive powers while the quality of the latter is determined indirectly from the current and voltage. For single-phase circuits with polyharmonic currents and voltages according to known methods of Fourier analysis in a trigonometric form the calculation of the instantaneous power was performed and its components were determined. Components of power, which are caused by different frequency components of the current and voltage, were considered as a separate group. It was noted that these components, their combinations, or their effective values can be used to estimate the quantity and quality of electric energy. originality. It has been established that measuring the amount of the electricity consumption and estimating its quality indicators by the level of voltage do not allow taking into account the poor quality of energy consumption or energy supplying properly and, consequently, differentiating the amount of low-quality and hi-quality product (energy). Practical value. The procedure for determining the components of power for estimating the flow of energy at the metering point was proposed with presenting currents and voltages as polyharmonic periodic functions, which is a common technique in electrical engineering.
Purpose
At the current stage of electrical technology development, it is relevant to take into account the quality of electrical energy. It can be implemented if an assessed energy quality indicator is available. The amount of electrical energy is determined by active power, which is transmitted over a certain time period. In some cases, reactive power is included in the metering system. The distortion power is justifiably criticized and is not taken into account. The purpose of this paper consists in the substantiation of the indicator of the distortion of the periodic polyharmonic current electrical energy power, by separating from the instantaneous power such harmonics, which formed by same frequencies current and voltage harmonics.
Design/methodology/approach
Using the method of calculating linear polyharmonic current circuits, the following quantities are identified in instantaneous power: active, reactive and apparent powers of each harmonic. These components are known from references as canonical.
Findings
By the method of instantaneous power harmonic analysis, the components formed by current and voltage harmonics of the same frequency and different frequencies are distinguished.
Research limitations/implications
The RMS value of the instantaneous power due to current and voltage harmonics of different frequencies is justified in the work. This quantity allows you to distinguish the instantaneous power distortion level in comparison with the existing quantity.
Practical implications
The results can be used to assess the level of instantaneous power distortion level in commercial and technical metering systems.
Originality/value
The definition of instantaneous power distortion by extracting the canonical components from it and determining the root mean square value of the remainder is proposed.
The development of electric power industry is accompanied by an increase in the number of consumers subjected to loads with nonlinear characteristics. The arising problem of the distortion of electrical energy that takes place when the mentioned consumers are in operation is partially solved by using means of improving the quality of electrical energy. The increase in the share of small generating plants that are placed in the nodes of consumers exacerbates the interaction of non-linear loads, forming additional parallel streams of electrical energy. Distorted electrical power is not an indication to account. Existing views on distorting power are amenable to criticism. In the well-known works, the proposals for the assessment of power using the quadratic norm and the quadratic norms of its components have been grounded. For the analysis of processes of formation the components of electrical power, a diagram of the simplest circuit containing a series-connected source of electromotive force, resistors and a diode is considered; also, the circuit was conditionally separated into a source and a consumer. The analysis of the power formation of each circuit element is performed with the use of the expression of current and voltage, as periodic functions represented by the trigonometric form of Fourier series. The power components are separated with the use of the known interaction of harmonic components of current and voltage of different orders. For the circuit elements, the power components formed by current and voltage harmonics of the same order are selected as well as power components formed by current and voltage harmonics of different orders, in which, in their turn, the power components are selected that have the same order as the first ones. The power formed by the action of the latter group is proposed to be attributed to the distorting power and to account its action by the corresponding quadratic norm. A numerical calculation has been performed with a use of the specified power component distribution. Time diagrams illustrate the process of interaction of the power components, which–in the case of the diode–leads to no change in power over time.
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