Between the transmission networks of 50Hertz and the Czech transmission system operator ČEPS, one cross-border power line exists (see graphic). This AC line between the substation Röhrsdorf (Germany) of 50Hertz and the substation Hradec (Czech Republic) of ČEPS is in operation since 1959. At the beginning, this line was operated with a nominal voltage of 220 kV. Since an upgrade in 1976 the line is operated with an operating voltage of 380 kV until today.
In order to increase the regulation possibilities of cross-border power flows 50Hertz and ČEPS install phase shift transformers (PST) on the interconnector which are operated in a coordinated manner. The first PSTs on the German-Czech interconnector have been commissioned by ČEPS in the Hradec substation in January 2017. On the German side, two PSTs have been commissioned by 50Hertz in the substation Röhrsdorf end of 2017. After some further reconstruction works in the substation Röhrsdorf, that are expected to take another two years time, the possibility of switching the PST into other lines in the southern region of the 50Hertz control area will be established in order to enable improved utilization of these lines.
Further information regarding the PST projects of 50Hertz and ČEPS:
press release: Regular operation of phase shifting transformers started
press release: Electricity flows between 50Hertz and CEPS regulated by phase-shifting transformers
press release: Building permit granted for phase shifters