Power transmission line uprating and reliability improvement

The first step in the process of uprating is to collect as much detailed information about the line as possible. With second to none experience in airborne LiDAR surveys of power transmission lines OPTEN obtains accurate data on power line location detecting impairing clearances:

•    conductor clearance to ground;
•    crossed lines and vegetation;
•    current density;
•    technical condition of conductors;
•    actual conductor temperature data.

For direct measurement of conductor temperature and current specially elaborated devices for online transmission line monitoring (OTLM, fig.1) are fastened to conductors of the surveyed line and power supplied by power distraction from live power line conductor.

Values of measured conductor current and temperature are transmitted via cell telephony channels to receiver installed at the power utility control board. Measurement accuracy amounts to 10 C for conductor temperature and 1 A for current. The device is equipped with a receiver of GPS signals. Due to this, temperature and current measurement data is time annotated.

Conductor temperature and current together with the data on the position of power transmission line elements in relation to the adjacent objects and terrain allow predicting the conductor behavior under various current load conditions. During this procedure we distinguish critical locations where due to the transmitting capacity increase conductor temperature will rise causing sag increase and clearance violation.

With all this information at hand quick and efficient engineering solutions ensuring an opportunity of considerable increase of transmitted power are elaborated.

The following practical means can be applied to achieve essential active power increase by more efficient use of existing network infrastructure objects:

•    use of real time monitoring systems;
•    applying flexible rating;
•    reconductoring (equate to 2/3 of additional circuit construction cost);
•    clearance control;
•    conductor retention.

Fig. 1. Online
Transmission
Line Monitoring