Cascaded converter station and cascaded multi-terminal HVDC power transmission system

摘要

A cascade converter station and a multi-end cascade high-voltage direct current (HVDC) power transmission system. The converter station includes a low-voltage end converter station (11) and a high-voltage end converter station (12). The high-voltage end converter station (12) is connected in series with the low-voltage end converter station (11) through a medium-voltage direct current (DC) power transmission line (13) and connected to a HVDC power transmission line (14). With the cascade converter station and the multi-end cascade HVDC power transmission system, HVDC power transmission can be achieved in a flexible, reliable and economical manner.

主权项

1. A cascaded converter station used in cascaded multi-terminal HVDC power transmission, comprising a low-voltage end converter station and a high-voltage end converter station, wherein,
the low-voltage end converter station has a first positive side and a first negative side, each of the first positive side and the first negative side comprising:
(i) a first converter transformer coupled to a first alternating current (AC) network;(ii) a first converter valve coupled to the first converter transformer for realizing DC/AC conversion; and(iii) two first smoothing reactors, wherein each of the two first smoothing reactors is provided on each of both ends of each first converter valve; wherein the high-voltage end converter station is connected in series to the low-voltage end converter station through a middle-voltage DC power transmission line, and is connected to a high-voltage DC power transmission line, wherein the high-voltage end converter station comprises a second positive side and a second negative side, each of the second positive side and the second negative side comprising:
(i) a second converter transformer coupled to a second alternating current (AC) network;(ii) a second converter valve coupled to the second converter transformer for realizing DC/AC conversion; and(iii) two second smoothing reactors, wherein each of the two second smoothing reactor is provided on each of both ends of each second converter valve; wherein a grounding line coupled to a grounding electrode and a metal return line coupled between a positive line and a negative line are provided in the low-voltage end converter station.