US 11,817,709 B2
Method for stabilizing an AC voltage grid
Ralph Morgenstern, Erlangen (DE); Markus Naukamm, Erlangen (DE); Bjoern Hellfritzsch, Fuerth (DE); and Andreas Haselbauer, Erlangen (DE)
Assigned to Siemens Energy Global GmbH & Co. KG, Munich (DE)
Filed by Siemens Energy Global GmbH & Co. KG, Munich (DE)
Filed on Sep. 2, 2021, as Appl. No. 17/464,902.
Claims priority of application No. 20194111 (EP), filed on Sep. 2, 2020.
Prior Publication US 2022/0069583 A1, Mar. 3, 2022
Int. Cl. H02J 3/30 (2006.01); H02J 3/18 (2006.01)
CPC H02J 3/1885 (2013.01) [H02J 3/1878 (2013.01); H02J 3/30 (2013.01)] 3 Claims
OG exemplary drawing
 
1. A method for stabilizing an AC voltage grid, which comprises the steps of:
providing a rotating phase-shifter that exchanges reactive power with the AC voltage grid during normal operation;
connecting the rotating phase-shifter to the AC voltage grid by way of a converter upon identification of a predetermined frequency drop in the AC voltage grid;
disconnecting the rotating phase-shifter from the AC voltage grid, upon identification of a frequency drop, by opening a switch and instead connecting the rotating phase-shifter to the AC voltage grid via the converter by further closing an input switch between the rotating phase-shifter and the converter; and
feeding stored energy of the rotating phase-shifter into the AC voltage grid in a form of active power.