Study for Arrangement of the Smoothing Reactor in ±800kV UHVDC Project

Normally, the smoothing reactor in plusmn500 kV HVDC system is installed on the pole bus. It's the first time for the application in UHVDC project of the 50/50 split of the smoothing reactor, i.e. half of the required smoothing reactance of the converter station is connected with pole bus and the rest is connected with the neutral bus. In this article, in comparison with the scheme of all smoothing reactors installed on DC pole bus, the influences of the smoothing reactors connected with pole bus and neutral bus on the system peak/crest of the continuous operating voltage (PCOV/CCOV) and on the insulation coordination of the converter station are focused on discussion. Also the PSCAD/EMTDC program is used for the DC transient overvoltage (DCTOV) calculation in detail for arrangement schemes comparing. All of the studies is based on the Yun-Guang plusmn800 kV UHVDC project. With considering of the type selection, manufacture and the investment of the smoothing reactor, the conclusion will be drawn in this article: the different smoothing reactor arrangement scheme will bring the obvious influence on the production, transport and the cost of the important equipment in the UHVDC project. After the issues are analyzed economically and technically, the optimum scheme with split installation of the smoothing reactor is determined finally.