Abstract
The resistance of overhead power lines depends to a large extent on the temperature of the conductor. It is known that the current flowing heats the conductor, but the environmental conditions also influence the heat transfer. The classical approach in determining the limiting active power flow over a transmission line does not take into account thermal processes, considering these factors as independent. This, in turn, can lead to errors in determining the allowable power overflow. The paper proposes a method for calculating steady-state conditions with consideration of thermal processes in elements to analyze the stability of power systems. It is shown that the presented method makes it possible to determine with the necessary accuracy the limiting power flow taking into account thermal processes. It is also necessary to refer to the advantages of the method that in addition to traditional technical limitations in the case of heavy modes (voltages, currents) it allows introducing restrictions on the maximum permissible temperature of both transmission lines and transformers. According to the results of the simulation, it was found that the overflow of active power in the limit mode, taking into account thermal processes in the winter period for the considered electrical system amounted to 459.32 MW, which is 190.82 MW more than the overflow without taking into account thermal processes. In the summer period the overflow amounted to 347.29 MW, which is 78.79 MW higher. The results obtained show that thermal processes in the electrical network elements can significantly affect the limit of transmitted power under different climatic factors and seasons. The analysis carried out in the paper emphasizes the need to take into account the thermal balance in the design and operation of electrical networks of different voltage classes.
Keywords
electric power system, permissible power flow, mode weighting, internal temperature correction, thermal balance equation
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