In order to better control cross-border electricity flows, 50Hertz and PSE are installing phase shifting transformers (PSTs) on the two existing interconnectors which are operated in a coordinated manner.
After the successful commissioning of the first four PSTs at the Polish substation in Mikułowa in June 2016, the northern interconnector between Vierraden and Krajnik was temporarily taken out of operation in order to upgrade the two substations to 380 kV. In August 2018 the first two PSTs were commissioned in Vierraden. While the line to Poland is operated at 380 kV, on the German side there is a link to the existing 220 kV lines as construction of the 380 kV Uckermark Line is delayed. In addition to the two PSTs, two 380/220 kV transformers will be used as an intermediate step. With the commissioning of the Uckermark Line, these two 380/220 kV transformers will be replaced by two more PSTs. After that, the installation of the PSTs in Vierraden will be completed and another important development project can be put into full operation within the European interconnected grid.
PST in the substations Mikułowa, Vierraden, Hradec and Röhrsdorf (on the German-Czech border) are operated by 50Hertz, PSE and ČEPS in a coordinated manner.
Further information regarding the PST projects of 50Hertz and PSE:
Press release: Power flow regulation between Germany and Poland (German)
Press release: Agreement between Polish and German transmission system operators signed (German)
Pilot and Operational Phase of “virtual Phase Shifting Transformer” (vPST) on the interconnectors between Germany and Poland
Before commissioning of the first four PSTs in Mikułowa in June 2016, a so-called "virtual Phase Shifting Transformer" (vPST) was operated to control unplanned load flows, ensure system security and foster cross-border electricity trading.In March 2014, 50Hertz and PSE launched the operational phase of the vPST. Beforehand, the partners tested the vPST mechanism during its pilot phase and drew conclusions for the subsequent operational phase. The report prepared jointly by both transmission system operators presents the principles, assignments and most important results of the vPST pilot phase.
Further information regarding the virtual phase shifting transformer of 50Hertz and PSE:
Press release: 50Hertz and PSE Operator cooperate to use phase shifting transporters
Report on vPST pilot phase experience