OMICRON Magazine

Magazine | Issue 1 2022 14:53:30 14:54:00 14:54:30 14:55:00 14:55:30 14:56:00 14:56:30 0 50 100 150 200 0 50 100 150 250 200 300 350 400 14:57:00 14:57:30 14:58:00 1 2 3 PhA-G PhB-G PhC-G VPhPh (kV) VPhG (kV) VPhPh-ATF = ø 407 kV site in Lippendorf was carried out within roughly 40 seconds. To balance out the switching operations in the next test steps, the operating mode of the generator excitation system was switched to “Automatic voltage control” (time point 1). The subsequent voltage dip was a result of not all signals being updated within the controller After a blackout in the transmission network, the power supply must be restored as quickly and safely as possible. In October 2020, an alternative grid restoration strategy using a ramp-up network was used in a prepared island network by German transmission grid operator 50Hertz as part of a pilot test. In the first part of the paper (published in the OMICRON Magazine 2/2021), we introduced you to the initial situation and preparations for the test. Now you can find out more about how the practical test was carried out, the unexpected results, and the knowledge gained from it. Ramping up to nominal voltage In the first part of the grid restoration test, the de-energized test network was continuously ramped up, considering the available water volume in the Goldisthal pumped storage power plant. In doing so, the generator voltage was increased from 0 kV to 18 kV nominal voltage in the “Manual excitation current control” operating mode. The resulting voltage curve in the Altenfeld substation can be seen in Figure 1. As expected, the continuous voltage ramp-up to the power station Figure 1: Voltage curve in the Altenfeld substation; ramping up of generator voltage. «The initial change in the excitation system operating mode should occur with a delay in the future, so it doesn’t have to leave its stable operating state.» Missed the first part? The first part of the article dealt with the initial situation and test preparations. Scan the QR-Code or visit: 31