US 11,837,868 B2
Photovoltaic system and leakage current control method for photovoltaic system
Xiaoqian Meng, Shanghai (CN); Haibin Guo, Shanghai (CN); and Yongbing Gao, Shanghai (CN)
Assigned to Huawei Digital Power Technologies Co., Ltd., Shenzhen (CN)
Filed by Huawei Digital Power Technologies Co., Ltd., Shenzhen (CN)
Filed on Mar. 25, 2022, as Appl. No. 17/704,120.
Claims priority of application No. 202110329154.5 (CN), filed on Mar. 27, 2021.
Prior Publication US 2022/0311246 A1, Sep. 29, 2022
Int. Cl. H02J 3/38 (2006.01); H02S 40/32 (2014.01); H02M 7/537 (2006.01)
CPC H02J 3/381 (2013.01) [H02M 7/537 (2013.01); H02S 40/32 (2014.12); H02J 2207/20 (2020.01); H02J 2300/24 (2020.01)] 13 Claims
OG exemplary drawing
 
1. A photovoltaic system comprising:
at least one photovoltaic module group;
at least one photovoltaic inverter;
a grounded metal frame; and
a sampling control unit, wherein the at least one photovoltaic module group is mounted on the grounded metal frame, an output end of the at least one photovoltaic module group is connected to an input end of the at least one photovoltaic inverter, an output end of the at least one photovoltaic inverter is connected to a power grid, the sampling control unit is coupled to both the at least one photovoltaic module group and the at least one photovoltaic inverter, and is configured to:
detect a current value of a leakage current formed by a common-mode voltage of the at least one photovoltaic inverter on a parasitic capacitor, wherein the parasitic capacitor exists between the at least one photovoltaic module group and the grounded metal frame;
adjust an injection amount of the common-mode voltage in a pulse width modulated signal of the at least one photovoltaic inverter based on the detected current value of the leakage current to reduce the leakage current;
when detecting that the current value of the leakage current is greater than a current threshold, reduce a common-mode injection coefficient of the pulse width modulated signal of the at least one photovoltaic inverter to reduce the injection amount of the common-mode voltage in the pulse width modulated signal; and
when a modulation ratio for pulse width modulation of the at least one photovoltaic inverter is less than or equal to one, reduce the common-mode injection coefficient of the pulse width modulated signal of the at least one photovoltaic inverter until the common-mode injection coefficient is zero.