Dynamic No-Load DC Voltage Control Strategy for High-Voltage DC Transmission

The HVDC transmission system achieves power regulation by fast control of the converter trigger phase. In addition, in order to expand the power regulation range and keep the system in a good operating condition, it is supplemented by converter transformer tap regulation. In this paper, we first analyse the tap regulation strategy in the existing technology, and put forward the dynamic no-load DC voltage method, i.e., according to the mathematical model of the high-voltage DC transmission system, we establish the dynamic no-load DC voltage reference value and the function relationship of DC power, and control the trigger angle or the shut-off angle with the increase of the DC power to reduce, so as to avoid the reciprocal regulation of the tap changer affecting the service life of the tap changer or even causing damages, and at the same time avoid the large fluctuation of reactive power. At the same time, large fluctuations in reactive power are avoided.