Abstract
Due to the existence of thermal capacity, the conductor temperature of overhead line and cable changes later than current steps (thermal inertia), and the thermal dynamic process of the conductor contains the huge current-carrying potential. As an important symbol of thermal dynamic process, the thermal inertia time constant is of great significance to describe the characteristics of thermal dynamic process accurately. In this paper, the thermal inertia time constants of overhead line and cable and its influencing factors are studied based on the heat balance models, which can be solved by the fourth order Runge-Kutta method. Then the four factors including the current step, ambient temperature, wind speed and global radiation intensity are used to explore their influence on the thermal inertia time constant of overhead line, and the current step and soil temperature on cable. The numerical results show the effects of influencing factors on the thermal inertia time constant and provide a theoretical basis for a more detailed evaluation of the thermal dynamic process.
Highlights
With the rapid development of the economy, the power demands of users are growing and a large number of clean energy sources are connected to power grids, which makes the load and volatility of the power grid increase significantly in the operating environment
By combining DTR technology and heat balance models with power system analysis and decision control, the dynamic thermal rating methods with forecasting [7], power system reliability evaluation [8] and control decision methods [9] were further studied in order to ensure the safe and economic operation
In [14], the paper further presented a power flow calculation method considering the thermal behavior of overhead line, cable and transformer, and results showed that the thermal inertia time plays a crucial role in the security check and contingency analysis, revealing the current-carrying potential to operators
Summary
With the rapid development of the economy, the power demands of users are growing and a large number of clean energy sources are connected to power grids, which makes the load and volatility of the power grid increase significantly in the operating environment. Based on this, [10] and [11] put forward the concept of electrothermal coordination (ETC), which expressed the transmission limitation as temperature firstly The core of it is to introduce the temperature as the state variable into the power system analysis and optimized decision, and exploit the current-carrying capacity of transmission elements by making full use of the thermal dynamic process. In [14], the paper further presented a power flow calculation method considering the thermal behavior of overhead line, cable and transformer, and results showed that the thermal inertia time plays a crucial role in the security check and contingency analysis, revealing the current-carrying potential to operators. This paper studies the thermal inertia time constants and its influencing factors of overhead line and cable based on the heat balance models, which lays the foundation for further exerting the current-carrying potential in the thermal dynamic process of power system
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