A survey of sag monitoring methods for power grid transmission lines

Abstract

The transmission line is a fundamental asset in the power grid. The sag condition of the transmission line between two support towers requires accurate real-time monitoring in order to avoid any health and safety hazards or power failure. In this paper, state-of-theart methods on transmission line sag monitoring are thoroughly reviewed and compared. Both the direct methods that use the direct video or image of the transmission line and the indirect methods that use the relationships between sag and line parameters are investigated. Sag prediction methods and relevant industry standards are also examined. Based on these investigation and examination, future research challenges are outlined and useful recommendations on the choices of sag monitoring methods in different applications are made.

Contactless current measurement for suspended overhead lines using a magnetic field sensor array

“…where μ 0 denotes the permeability in free space (4π × 10 −7 T⋅m/A); d ⇀ l denotes the unit vector of the current-carrying cable; and ⇀ r indicates the vector of distance r. The magnetic flux density generated by the current unit element of each line segment at point P is summed and expressed as (2).…”

“…In power systems, high-voltage transmission lines are used as the primary method of energy distribution, and their stable operation is of great significance to ensure power supply reliability and improve system efficiency. Therefore, the condition monitoring and fault diagnosis of high-voltage transmission lines are particularly important [1,2]. Traditional current measurement methods, namely, current transformers (CTs), have problems such as bulky size, high costs, hysteresis saturation, and high risk of electric shock [3,4].…”

Study on Real-Time Spatial Distance Acquisition Method of Transmission Line Based on Laser Point Cloud and Image Monitoring

“…Lidar technology has been well used in the survey and design of domestic power system, but its application in the inspection of power system is still in the exploratory stage. In the current power system, in the inspection experiment of manned and unmanned helicopters, the inspection platform is mostly equipped with conventional observation means such as infrared thermal imaging and telephoto camera to monitor the path [2]. The Central China Power system adopts the satellite image acquisition method to collect the multi-view image of the transmission line.…”