Receiving end layered access UHVDC low-load reactive power control method and control device

The invention discloses a receiving end layered access UHVDC low-load reactive power control method and control device for achieving independent control of reactive power of two AC grids at a receiving end in a receiving end layered access UHVDC system low-load operation mode. In the bipolar layer control, reactive power exchange values of AC/DC systems in the two AC grids at the receiving end aredetected in real time and are sent as feedback values respectively to two independent low-load reactive power controllers, and trigger angle or extinction angle reference values for controlling the reactive power loss of high-end and low-end valve groups are respectively calculated. In the converter layer control, the independent control of the reactive power loss of the high-end and low-end valve groups is realized through the coordinated control of converter tapped control, converter trigger control and valve group voltage-sharing control. This technical scheme not only can realize the independent control of AC and