US 11,808,794 B2
Method and device for approximately determining voltages at a high-voltage side of a transformer
Vitali Sakschewski, Gudensberg (DE); Thorsten Buelo, Kassel (DE); and Florian Rauscher, Braunschweig (DE)
Assigned to SMA Solar Technology AG, Niestetal (DE)
Filed by SMA Solar Technology AG, Niestetal (DE)
Filed on Sep. 7, 2021, as Appl. No. 17/467,625.
Application 17/467,625 is a continuation of application No. PCT/EP2020/055818, filed on Mar. 5, 2020.
Claims priority of application No. 10 2019 105 861.9 (DE), filed on Mar. 7, 2019.
Prior Publication US 2021/0396790 A1, Dec. 23, 2021
Int. Cl. G01R 19/25 (2006.01); G01R 31/62 (2020.01); G01R 29/16 (2006.01); G01R 31/42 (2006.01)
CPC G01R 19/2513 (2013.01) [G01R 29/16 (2013.01); G01R 31/42 (2013.01); G01R 31/62 (2020.01)] 16 Claims
OG exemplary drawing
 
1. A method for an approximate determination of voltages at a high voltage side of a transformer based on measured voltages at a low voltage side of the transformer, comprising:
measuring delta voltages and string voltages and phase angles at the low voltage side of the transformer using a voltage measurement and transformation circuit;
transforming the string voltages and phase angles into positive and negative sequence voltages and phase angles of the positive and negative sequence systems, respectively, at the low voltage side of the transformer using the voltage measurement and transformation circuit;
determining positive and negative sequence voltages and phase angles of the positive and negative sequence systems, respectively, at the high voltage side of the transformer from the positive and negative sequence voltages and phase angles of the positive and negative sequence systems, respectively, at the low voltage side of the transformer using a processing circuit;
determining estimates of a zero-sequence voltage and a phase angle of a zero-sequence system at the high voltage side of the transformer from the measured delta voltages and string voltages and phase angles at the low voltage side of the transformer using the processing circuit; and
transforming the positive, negative and zero sequence voltages and the phase angles into string voltages and/or delta voltages at the high voltage side of the transformer using a re-transformation circuit.