US 11,841,724 B2
MLPE photovoltaic system and method for photovoltaic string control in MLPE photovoltaic system
Yu Yang, Hefei (CN); Yuqi Peng, Hefei (CN); and Jun Xu, Hefei (CN)
Assigned to Sungrow Power Supply Co., Ltd., Hefei (CN)
Filed by Sungrow Power Supply Co., Ltd., Hefei (CN)
Filed on Nov. 5, 2021, as Appl. No. 17/519,659.
Claims priority of application No. 202011252428.7 (CN), filed on Nov. 11, 2020.
Prior Publication US 2022/0147090 A1, May 12, 2022
Int. Cl. G05F 1/67 (2006.01); G05F 1/06 (2006.01); G05F 1/573 (2006.01)
CPC G05F 1/06 (2013.01) [G05F 1/5735 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A method for photovoltaic string control in a module level power electronics (MLPE) photovoltaic system, the method being applicable to a control unit in the MLPE photovoltaic system, and the method comprising:
detecting an output current of each photovoltaic string in the MLPE photovoltaic system;
determining whether the MLPE photovoltaic system has unbalanced string currents; and
if it is determined that the MLPE photovoltaic system has unbalanced string currents, controlling, for photovoltaic strings connected in parallel to a same inverter in the MLPE photovoltaic system, a voltage of a photovoltaic string with a larger output current to be reduced, or controlling a voltage of a photovoltaic string with a smaller output current to be increased, to reduce a backflow current to a preset range, wherein the backflow current is a current that is generated by the photovoltaic string with the larger output current and flows into the photovoltaic string with the smaller output current,
wherein the inverter samples the output current of each photovoltaic string separately.