US 12,438,373 B2
System and method for unbalanced current adjustment from capacity enhancement and split-phase output of distribution transformer
Jindong Yang, Kunming (CN); Hongwen Liu, Kunming (CN); and Fei Rong, Kunming (CN)
Assigned to ELECTRIC POWER RESEARCH INSTITUTE OF YUNNAN POWER GRID CO., LTD, Kunming (CN)
Appl. No. 18/558,352
Filed by ELECTRIC POWER RESEARCH INSTITUTE OF YUNNAN POWER GRID CO. , LTD, Kunming (CN)
PCT Filed Feb. 14, 2023, PCT No. PCT/CN2023/075845
§ 371(c)(1), (2) Date Oct. 31, 2023,
PCT Pub. No. WO2024/001202, PCT Pub. Date Jan. 4, 2024.
Claims priority of application No. 202210736250.6 (CN), filed on Jun. 27, 2022.
Prior Publication US 2025/0070685 A1, Feb. 27, 2025
Int. Cl. H02J 3/18 (2006.01); H02J 3/26 (2006.01); H02M 7/5387 (2007.01); H02M 5/458 (2006.01)
CPC H02J 3/26 (2013.01) [H02J 3/1842 (2013.01); H02J 3/185 (2013.01); H02M 7/53871 (2013.01); H02M 5/458 (2013.01); H02M 5/4585 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A system and method for unbalanced current adjustment from capacity enhancement and split-phase output of a distribution transformer, which is applied to a power distribution system, the power distribution system comprising a distribution transformer and an a-phase line, a b-phase line, a c-phase line, and a neutral line n connected to a low voltage side of the distribution transformer, comprising:
a single-phase transformer, wherein an input end of the single-phase transformer is connected to any two phases of three-phase lines on a high-voltage side of the distribution transformer, the single-phase transformer is configured to change a high voltage of the distribution transformer into a low voltage, the single-phase transformer is further configured to increase capacity of a transformer area, the increased capacity of the transformer area is capacity of the single-phase transformer, and the capacity of the single-phase transformer is determined by a load size of the distribution transformer;
a single-phase bridge rectifier comprising a rectifier input end, a DC positive output terminal, and a DC negative output terminal, wherein the rectifier input end is connected to an output terminal of the single-phase transformer, the single-phase bridge rectifier is configured to convert alternating current at a low-voltage side of the single-phase transformer into direct current, which also inverts direct current into alternating current and transmits it to a power grid;
a three-phase full-bridge inverter comprising a positive inverter input terminal, a negative inverter input terminal, and an inverter output terminal, wherein the positive inverter input terminal is connected to the DC positive output terminal, and the negative inverter input terminal is connected to the DC negative output terminal, the inverter output terminal is connected to the a-phase line, the b-phase line, and the c-phase line respectively through a three-phase reactor, the three-phase full-bridge inverter is configured to output corresponding compensation currents respectively to the a-phase line, the b-phase line, and the c-phase line through the three-phase reactor, so as to perform three-phase unbalanced current adjustment;
a first filter capacitor connected to the positive inverter input terminal and the DC positive output terminal;
a second filter capacitor connected in series with the first filter capacitor, wherein the second filter capacitor is connected to the negative inverter input terminal and the DC negative output terminal, and the neutral line n is connected between the first filter capacitor and the second filter capacitor.