The use of a simplified formula for calculation of active power losses in transmission lines taking into account the temperature in the stationary thermal regime is considered. The results of the comparison of losses calculated using a simplified formula and based on the solution of the full heat balance equation for wires of various types are presented. The dependences of the calculating errors on the load current with and without solar radiation are constructed and analyzed.
Słowa kluczowe: bare and insulated wires, energy losses, temperature.
W artykule rozważa się korzystanie z uproszczonej formuły do obliczania strat mocy czynnej w linii z uwzględnieniem temperatury w trybie stacjonarnym cieplnym. Straty oblicza się według uproszczonego wzoru i w oparciu o równania bilansu cieplnego dla przewodów różnych typów. Zbudowane są i analizowane zależności błędów obliczeń od prądu obciążenia z promieniowania słonecznego i bez niego.
Keywords: gołe i izolowane przewody, straty energii, temperatura.
Load losses of energy in power lines account for about 85% of the total losses in the lines and about 55% of the total losses in the electrical networks of Russia. Improving the efficiency of power transmission imposes rather high demands on the accuracy of the calculation of losses. This in turn leads to the necessity of taking into account all the main factors determining the amount of losses. One of these factors is the temperature dependence of active resistance [1-3]. The papers in the field of accounting for the temperature of wires in the calculation of energy losses in electrical networks are rather popular nowadays [4-8]. However, the relevant methods are not widespread, in addition to the standards presented in [9-10]. For example, modern programs for calculating energy losses usually take into account only the dependence of active resistances on the ambient temperature, but not heating by current. The main reason for this is that a fairly large amount of additional input data is required to accurately calculate the temperature. The problem can be formulated as follows: it is required to develop such methods for calculating energy losses, which would take into account both the ambient temperature and the heating of the wires by the load currents, but would require a minimum amount of source data. In this article, a simplified formula for heat loss is compared with more complex methods. Basic equations and formulas In the established thermal mode, the surface temperature of the insulated wire Θsur can be calculated by the equation of heat balance per unit length of the line : (1) n sur env s s con inv sur env ins sur C T T A q d P S P 4 4 0 0 0 1 (1 ) where ΔP0 [...]
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