US 12,081,020 B2
Control method, computer program product, control system and use
Nicklas Johansson, Västerås (SE); Jan Svensson, Västerås (SE); Panagiotis Bakas, Västerås (SE); and Roberto Alves, Västerås (SE)
Assigned to HITACHI ENERGY LTD, Zurich (CH)
Appl. No. 18/281,362
Filed by HITACHI ENERGY LTD, Zurich (CH)
PCT Filed Feb. 24, 2022, PCT No. PCT/EP2022/054652
§ 371(c)(1), (2) Date Sep. 11, 2023,
PCT Pub. No. WO2022/189160, PCT Pub. Date Sep. 15, 2022.
Claims priority of application No. 21162435 (EP), filed on Mar. 12, 2021.
Prior Publication US 2024/0097442 A1, Mar. 21, 2024
Int. Cl. H02J 3/00 (2006.01); H02J 3/24 (2006.01); H02P 13/00 (2006.01)
CPC H02J 3/001 (2020.01) [H02J 3/241 (2020.01); H02P 13/00 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for controlling an output voltage of at least one transformer in a power grid, whereby said method comprises the steps of providing said at least one transformer with a power electronics converter, to thereby provide at least one power electronics enhanced transformer (PEET), and an output voltage controller, determining a grid frequency of said power grid, comparing said determined grid frequency with a reference value, producing an error signal corresponding to the difference between said determined grid frequency and said reference value, applying said error signal as feedback to said output voltage controller, and generating a control action to cause said output voltage controller to change the output voltage of said at least one transformer comprising a power electronics converter to limit the difference between the grid frequency and the reference value, whereby said power electronics converter is an AC-AC converter and said method comprises the steps of connecting said AC-AC converter to either a primary side or a secondary side of said a transformer, whereby said AC-AC converter has a first AC side and a second AC side and said method comprises the step of connecting two terminals on said first AC side in parallel to a winding or a part of a winding of said transformer, and connecting said second AC side directly to, or in series with an external circuit line, wherein said at least one PEET transformer has one of the following topologies:
a) voltage terminals on said first AC side are connected in parallel to one of the windings of said transformer, whereby said transformer has two windings on a PEET-side of said transformer which are isolated from each other, and voltage terminals on said second AC side of said AC-AC converter are connected in series with said external circuit line,
b) voltage terminals on said first AC side are connected in parallel to a part of the winding of said transformer and the voltage terminal on said second AC side of said AC-AC converter is connected directly to said external circuit line, wherein the winding is the only winding on a PEET-side of the transformer and said part of the winding is a portion that is less than an entirety of the winding.