US 12,334,739 B2
Hybrid direct current transmission system and control method thereof
Hua Li, Hohhot (CN); and Tianlong Hong, Hohhot (CN)
Filed by Inner Mongolia University of Technology, Hohhot (CN)
Filed on Jan. 16, 2025, as Appl. No. 19/024,817.
Prior Publication US 2025/0158411 A1, May 15, 2025
Int. Cl. H02J 3/36 (2006.01); H02J 3/38 (2006.01)
CPC H02J 3/36 (2013.01) [H02J 3/381 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A hybrid DC power transmission control method employing the hybrid DC power transmission which comprises a rectifier side circuit and an inverter side circuit, wherein:
the rectifier side circuit includes a grid commutation converter LCC and a modular multilevel converter MMC connected in series;
the inverter side circuit includes an LCC and three parallel MMCs, and the LCC and the three parallel MMCs are connected in series; and
the LCC of the rectifier side circuit and the LCC of the inverter side circuit are connected in series,
the method comprises:
in the rectifier side circuit, the MMC adopts a dual-loop control consisting of a power outer loop and a current inner loop to generate a trigger pulse signal for controlling each device in the MMC; and
the LCC adopts a constant DC current control, compares the current command value and the current measured value, performs proportional integral adjustment according to the comparison result, and controls the trigger angle of the LCC according to the adjustment result;
wherein, in the inverter side circuit, three groups of parallel MMCs adopt master-slave station switching coordinated control, one of the MMCs is set as the master station, adopts constant DC voltage control and constant reactive power control, and the other two MMCs are slave stations, adopting constant active power control and constant reactive power control;
wherein the LCC adopts constant DC voltage control, constant DC current control and constant shut-off angle control, and takes the maximum value as the signal for controlling the LCC trigger angle by comparing the output values of the three controls of constant DC voltage, constant DC current and constant shut-off angle control.