System and technology comparison of UHV transmission concepts

As the historical development shows, both AC and DC transmission voltages have steadily increased. The growing demand for power supply induced the building of large power plants located far away from load centres. Also future projects in Europe such as DESERTEC or large offshore Wind Power Systems demand a smart solution of transmitting electric bulk power in an economic and efficient way over long distances. In order to reach this goal, very high voltages for transmission are necessary. AC-Voltages ≥1000 kV und DC-Voltages ≥ ±800 kV are defined as Ultra- High-Voltages (UHV). Based on the assumption of a continuous growth of energy demand, experts considered the invention of UHV transmission level in North America and Europe already 40 years ago [1]. However - it took almost 4 decades till the first UHV AC line reached operational status in China. This paper demonstrates possible ways of transmitting large bulk power generated in offshore wind parks over a distance of roughly 600 km (about 380 miles) across Germany. It contains and discusses the results of the investigation for all relevant characteristics, fragmented into general, mechanical, electrical and ecological parameters. After a detailed look on the mechanical construction of UHV overhead transmission lines it could be stated, that this was one of the limiting factors. Also the maximum power, which could be injected into one grid point is a critical value and has influenced the reliability analyses.