Aerial barrage balls serve for marking high-voltage wires in order to visually warn pilots of civil and military aviation about the presence of overhead lines. The present article deals with the mechanical calculation of flexible overhead wires of overhead lines, in which aerial warning barrage balls are installed. The wire is considered as a homogeneous flexible thread having the outline of a parabola and a chain line. The load from the aerial barrage balls must not be substituted with a distributed one by simple division of the total load into the span length, since it can cause incorrect results. The formulas for determining the sag are given for a different number of aerial barrage balls as a function of their number and the coefficient of concentrated forces. The acceptable accuracy of mechanical calculation is demonstrated when using the model of wire in the form of a parabola adopted in the design practice, provided that the components of concentrated forces are correctly determined. The equation of state is recorded, taking into account the weight and wind loads on the wire, as well as load coefficients in two planes, depending on the number of barrage balls. The performed calculations demonstrate an acceptable accuracy of the determination of the stress at various loadings of the span. For more accurate calculation of mechanical stresses and sag arrows, a vector-parametric method for calculating the flexible wires of overhead lines is suggested, where the calculated model of wires in the form of a flexible elastic thread is put taking into account of the spatial arrangement of all structural elements. The results of mechanical calculation according to the program that had been developed and to the existing methods for a different number of aerial barrier balls moved along the span are presented.
Abstract.In recent years, electric energy storage systems are considered as a key element in the technological development of vehicles, renewable energy. This article provides a brief description of modeling methods, some new approaches and the results of modeling batteries in parallelto-serial assemblies that can be used to design storage units for local power systems. A battery is a very complex physicochemical, electrochemical and electrotechnical object, the modeling of which can be carried out at various depth levels and by various methods. Battery modeling options are being considered. Presentation of the battery in the form of equivalent circuits is in good agreement with the general approach of graphical representation of electrical systems in such packages as MatLab-Simulink, Electronics Workbench and the like. Two directions of battery modeling can be distinguished, viz. modeling current battery parameters during a charge-discharge cycle and modeling the parameters of the functional state of the batteries over a long period of operation. These directions consider different characteristic time periods (hours and days in the first case and hundreds of days in the second one), differ in the parameters taken into account and are relatively independent. The latest versions of MatLab-Simulink have a built-in model with degradation of battery parameters. The built-in battery model is quite complex and when simulating the operation of more than one battery, the time period of counting increases significantly. When modeling assemblies from a large number of batteries connected in parallel-to-series, the time in the program practically stops, which indicates the impossibility of modeling large assemblies. Nevertheless, the Electronics Workbench electronics lab has shown its performance. When using the similarity criterion, Electronics Workbench has the potential to complicate the circuits, which makes it possible to analyze parallel-serial battery assemblies.
The linear wind load on the wires and cables acting perpendicular to the wire depends on the angle between the direction of the wind and the axis of the overhead line. In the methodology of mechanical calculation of wires and cables, it is recommended to take the wind directed at an angle of 90° to the axis of span and it is not specified which side the wind blows from. For spans of air, this is not so much significant as for switchgear spans, where the deviations of the wires depend on the direction of action of the taps to the electrical apparatus. The article discusses various options for the location of taps and their effect on the wire, as well as changing the direction of the wind. An algorithm for calculating the horizontal deviation of a flexible wire and its increase coefficients in the presence of horizontal concentrated loads due to the action of windon spacers, barriers, taps to electrical apparatuses and other structural elements of substations and overhead lines is given. In the absence of wind, horizontal concentrated loads and deviations occur when an arrangement of the taps is non-keel. The formulas for calculating the horizontal component of the load coefficient to solve the equation of state in the presence of horizontal concentrated forces acting in any direction have been derived. The results of the mechanical calculation are obtained for the cases of one and two horizontal concentrated forces, differently oriented with respect to the distributed wind load. In design practice it is recommended to take the wind flow in the direction of the action of horizontal concentrated forces, since in this case the greatest horizontal deviations and load factors are obtained. The reduction in the coefficients of the horizontal load occurs when the current lead is unloaded because of the opposite directions of the wind and horizontal concentrated forces. In the absence of wind, it is proposed to use the formulas for calculating horizontal deviations and load after finding the product of the coefficient of increase in horizontal deviations and the horizontal component of the coefficient of load per linear load.
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