On the integration of self-commutated HVDC links into the european high-voltage transmission system

Offshore wind farms will contribute essentially to the generation of electrical energy in the coming years. In parallel, conventional power plants are going out of service. Especially in Germany the phase-out of nuclear power plants in the southern region of the country causes a significant regional power imbalance. Consequently, electrical energy has to be transported over long distances - a task which cannot be performed by the currently existing HVAC grid. With regard to losses and power per transmission line, DC transport is the most promising technology for this task. Consequently, the German grid-development plan currently lists four main DC transmission systems. With regard to grid integration, grid stability and reactive power demand, all these DC transmission systems will be based on self-commutated converter technology. This paper discusses potential concepts for an extended Europe-wide HVDC overlay grid supporting the existing HVAC grid.