Small series converter station specification and cost evaluation

Power systems planning studies should consider HVDC alternatives, mainly when long distances are involved. On this context emerges the question about the economical and technical viability of supplying small loads along the lines. Looking for an answer that could orient its planning studies, the authors developed a methodology for the preliminary calculations comprised in a natural commutated series convertor station (SCS) design, which allows for the basic parameters determination, including extinction angle and tap changer ranges, converter transformer ratings and reactive power demand. This methodology takes into account all factors, practical aspects and limitations involved in such a study. The authors show the above mentioned method applied to a 25 MW SCS to supply a small load from a HVDC link rated to 350 kV and 500 MW per pole. The AC filters and the synchronous condensers were also evaluated, concluding the main equipment basic specification