Increasing the Utilization of Transmission Lines Capacity by Quasi-Dynamic Thermal Ratings

Abstract

The power grid is under pressure to maintain a reliable supply because of constrained budgets and environmental policies. In order to effectively make use of existing transmission lines, it is important to accurately evaluate the line capacity. Dynamic thermal rating (DTR) offers a way to increase the utilization of capacity under real-time meteorological data. However, DTR relies on a number of sensors and the cost is high. Therefore, a method of improving the utilization of capacity by quasi-dynamic thermal rating (QDR) is proposed in this paper. QDR at different confidence levels and time scales is determined through the statistical analysis of line ampacity driven by key parameters, and the key parameters is identified by control variate method. In addition, the operation risk and tension loss is evaluated. The results show that QDR can increase the utilization of line capacity and in the absence of along-line measuring devices, QDR is more accurate, reliable and cost-saving. The managers can determine the appropriate confidence level according to the operation risk and tension loss that the system can bear, and shorten the time scale with the permission of the operation and control complexity.

An Equivalent Heat Transfer Model Instead of Wind Speed Measuring for Dynamic Thermal Rating of Transmission Lines

“…According to the IEEE standard, R(T c ) is the function related to the conductor temperature. When the maximum allowable temperature of conductor T cmax is given, the calculation formula of the conductor ampacity I amp can be derived by (1), as shown in (2).…”

“…To achieve this, the direct solutions are establishing new transmission lines or replacing overhead conductors which have greater power transfer capacity. However, there are some restrictions in these solutions, including the difficulties of land expropriation, long construction time and high costs [1,2]. Therefore, it is increasingly essential to maximize the utilization for power transfer capacity of the existing overhead conductors [3,4].…”

Corrective Control by Line Switching for Relieving Voltage Violations Based on A Three-Stage Methodology

“…We consider a comprehensive power system quasi-steady-state model of the following general form: 0 = f (x) (1) where x is the vector of state variables.…”

“…It is widely known that the modern power grid is a large-scale and extremely complex interconnected network. Fulfilling the demand for electric power is essential from economic, protective, and societal standpoints [1,2]. Unfortunately, it is not easy to keep the grid running at a stable point all the time: voltage variation problems seriously affect the stable operation of the system.…”