: 1) Increase the trigger Angle of the rectifier or the trigger Angle of the inverter.
2) Use the rheological tap adjustment to reduce the AC side voltage of the converter, so as to achieve the purpose of reducing the DC voltage.
3) When the HVDC project has two groups of basic converter units connected in series per pole, the method of locking a group of converter units can be used to reduce the DC voltage by 50%.
4) When the DC transmission project is powered by an isolated power plant or the rectifier station adopts the unit connection mode of generator-transformer-converter, the excitation regulation system of the generator can be considered to reduce the voltage on the AC side of the converter to achieve the purpose of reducing the DC voltage.
There are two common methods of DC buck: linear buck and DC-DC transformation
1. Linear buck is relatively simple, generally used for low-power buck. The linear mode can only reduce the pressure, it is impossible to increase the pressure. Commonly used 78xx regulator blocks, etc., are linear regulators, the simplest kind of resistance step-down, but also in this way, the fundamental principle is the series circuit resistance voltage division law.
2. There are many kinds of DC-DC conversion circuits, among which Buck chopper circuit is commonly used for buck buck, which is a kind of switching power supply, and the efficiency is much higher than that of linear power supply at high power, but the circuit is also relatively more complex.