ADDITIONAL POWER LOSSES IN ELECTRICAL NETWORKS AT ASYMMETRICAL LOADING

2020 ◽  
Vol 3 (3) ◽  
pp. 35-42
Author(s):  
Gulasalkhon Musinova ◽  
Author(s):  
G. Georgiev ◽  
I. Zicmane ◽  
E. Antonov

Finding of the rational approach at the decision of a compensation in high-voltage networksThe aim of the present work is to find a computational model, sufficiently simplified for practical use which determines the sensitivity of the complex high-voltage electrical networks when switching compensatory powers. We show how this model can be used as a basis for creating practical criteria for a one-valued choice in the two situations. First, switching the compensatory power does not lead to leaving the permissible range of voltage. In this case the power which minimizes the power losses is used. Second, the compensatory power is switched in order to return the voltage to the permissible range. Then that compensatory medium is chosen which is sensitive enough in addition to causing the minimal increase in electrical power losses.


Vestnik MGTU ◽  
2020 ◽  
Vol 23 (4) ◽  
pp. 345-353
Author(s):  
E. I. Gracheva ◽  
A. N. Gorlov ◽  
A. N. Alimova

Determination of the main characteristics of the topology and technical condition of equipment underoperating conditions is necessary for analyzing and assessing power and electricity losses in intrashoplow-voltage industrial power supply networks. A comparative analysis of the technical characteristicsof automatic circuit breakers VA57-31 (KEAZ), NSX100 TM-D (Schneider Electric), DPX3 160 (Legrand), Tmax XT1 TMD (ABB) has shown that the main technical parameters of the machines are close in their values. At that it has been found out that automatic switches of the BA57-31 series have the lowest value of power losses per pole (7.5 W), whereas the automatic switches of the Tmax XT1 TMD series have the highest value (10 W). Thus, under the operating conditions of the equipment, the lowest value of power and electricity losses is characteristic of low-voltage electrical networks with installed circuit breakers of the BA57-31 series, and the highest value of losses is noted in in-shop systems with installed circuit breakers Tmax XT1 TMD. Using catalog data, the dependences of active power losses in circuit breakers on rated currents have been established; the algorithms have been developed and the obtained dependences have been modeled using approximating functions. The standard deviation of the compiled approximating functions has been calculated. Analytical expressions of the dynamics of power losses per pole have been determined as a function of the rated current. The graphical dependences of the investigated parameters of low-voltage equipment have been presented. The developed models are recommended to be used to increase the reliability of the assessment and refinement of the amount of active power and electricity losses in low-voltage electrical networks of industrial power supply systems, agrotechnical complexes, and enterprises of the public utility sector.


2019 ◽  
Vol 124 ◽  
pp. 02013 ◽  
Author(s):  
D. D. Micu ◽  
I. V. Ivshin ◽  
E. I. Gracheva ◽  
O. V. Naumov ◽  
A. N. Gorlov

This paper presents calculation of resistance of tightening contact joints of switching devices. It allows considering the technical condition of low-voltage switching equipment and to specify energy emitted in the switching device in the mode of electrical networks operation is presented in the article.


Author(s):  
M. A. Prishchepov ◽  
A. I. Zelenkevich ◽  
V. M. Zbrodyga

The problem of power quality supply is relevant for rural electrical networks, due to long distance and branching, as well as connection of a large number of single-phase and non-linear loads. Asymmetry of electrical loads causes voltage asymmetry, which adversely affects the operation of all elements of the electrical system, causing additional power losses, reducing the service life of electrical equipment and its economic performance, as well as reliability of operation of individual electrical equipment and power supply system as a whole. Reduction of voltage asymmetry can be ensured by rational construction of electrical network circuit and use of special correcting devices. The authors consider it reasonable to use relatively simple and reliable by design and inexpensive power transformers with a “star - double zigzag with a zero wire” (Y/2Zн) winding connection circuit with a neutral winding connection group. The paper deals with design and processes of converting electrical energy in a transformer. It has been proved that phase EMF of the secondary winding coincides in phase with the same EMF of the primary winding, i.e. the proposed circuit has a neutral windings’ connection group. Results of theoretical studies of transformer operation with an asymmetric and non-linear load are presented. Decrease in voltage asymmetry is due to the neutral sequence components compensation. Decrease of the higher harmonic voltage components level occurs due to the compensation of the higher harmonics multiplied three times. It is theoretically substantiated that transformer will not emit higher harmonic components of zero sequence voltages into the supply network. Experimental studies have confirmed the theoretical conclusions that a transformer with Y/2Zн winding connection circuit allows obtaining the highest level of voltage symmetry with an asymmetric load. In single-phase load mode, the values of voltage unbalance factor in reverse sequence do not exceed 1.7 %, in neutral sequence - 2.9 %. The transformer allows obtaining 1.2-1.5 times lower value of total harmonic components factor at non-linear load, which is the best result among circuits studied. This power transformer is resistant to load effects that distort voltage quality and is capable to provide a high level of symmetry and sinusoidal voltage as well as parallel operation with commercially available transformers. This makes it possible to use it in rural electrical networks to reduce power losses, increase service life and efficiency of electrical equipment, and increase reliability of the power supply system.


2021 ◽  
Vol 295 ◽  
pp. 02005
Author(s):  
Igor Naumov ◽  
Sergey Podyachikh ◽  
Dmitri Ivanov ◽  
Alexander Tretyakov ◽  
Andrey Bastron

The article discusses distribution electrical networks 0.38 kV operating modes, feeding individual residential buildings. The electrical energy parameters measurement were certified RESURS-UF2M device carried out. The currents and voltages time diagrams based on the measurements made and using Matlab technologies were constructed. It is established that the level of phase currents unbalance is quite high and causes significant three-phase power supply system unbalance voltage accordingly. The power of quality indicators - calculations, characterizing voltage unbalance were made, which were based on the measurements and the computer program “Asymmetry” was used. As well as the additional power losses coefficient determining by the phase currents unbalance, were calculations. Time diagrams these indicators are constructed and their analysis were made. As a result, the power of quality is significantly reduced by unbalance power consumption in the studied electrical network were founded. At the same time, the additional power losses are significant increases. Specific recommendations for the normalization electrical network-operating mode are given.


2020 ◽  
Vol 209 ◽  
pp. 02004
Author(s):  
Roman Belyaevsky ◽  
Alexey Gerasimenko

Improving the energy efficiency of the power grid complex is an urgent problem. The need to solve this problem is due to various technical and economic reasons. First of all, this is due to high power losses in distribution electrical networks, caused by a significant load of its elements by reactive power flows. In this regard, the development of mechanisms for active-adaptive control of reactive power is becoming increasingly important. Currently, the Smart Grid concept has become widespread in the global electric power industry. The use of these technologies allows not only to optimize power losses in distribution networks, but also to improve the efficiency of the electric grid complex. The article proposes an algorithm for optimizing the placement of compensating devices in the distribution network on the example of one of the territorial network organizations of the Kuzbass. This algorithm is based on the theory of multilevel systems using the method of indefinite Lagrange multipliers. The results of applying this algorithm based on the developed simulation model are presented.


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