One instrument to this end is the so-called overhead line monitoring, also referred to as weather-dependent overhead line operation. The background is that the transmission capacity of overhead lines is limited by the maximum operating temperature of the conductor. If more electricity flows through the line, the transmission lines heat up. Wind and cold can cool off the lines. During overhead line monitoring, we permanently survey the operating temperature of lines and can transport more electricity in case of cold weather or strong wind.
Another way to optimise existing lines is to install high-temperature transmission lines. These can be subjected to a higher operating temperature and therefore transport more electricity. This does not require the construction of a new line, but only the replacement of the transmission lines on the towers of an existing overhead line. 50Hertz for example installed high-temperature transmission lines on the important north-to-south line from Remptendorf in Thuringia to Redwitz in Bavaria without having to replace the towers on this section.
Since early 2018, so-called phase shifting transformers (Download in German) have been installed that also enable more effective exploitation of the existing grid. Phase shifters can be compared to a valve that controls the flow of electricity. Because of this redirection of the energy to other lines, the stress on certain line sections is relieved. So far, 50Hertz has put phase shifting transformers in substations Vierraden (Brandenburg) and Röhrsdorf (Saxony) into operation, with the primary objective to reduce unplanned load flows via cross-border connections to Poland and the Czech Republic. After the completion of the conversion works in Vierraden and Röhrsdorf, it will also be possible to use these phase shifting transformers to improve the distribution of electricity within the 50Hertz grid as well.