Some of the above-listed disadvantages can be eliminated with the use of new technologies. In particular, disadvantages such as a complete power fault of the HVDC transmission system during short-circuits inthe AC power system and reactive power consumption can be eliminated completely, or mostly, with the use of turn-off thyristors.Several research centers are working on improving high-capacity turn-off thyristors and also on new types of converter devices for high-capacity HVDC transmission.Finally, there are several new techniques for the perfection of grounding devices, providing for decreased electro-corrosion impacts and the formation of so-called “metal return”, which precludes the working current from flowing through the ground. Other techniques aimed at perfecting HVDC technology are also being developed (Koshcheev 2001).
Colin Bennett on 06 Feb 12The battery technology for plug-in HEVs and EVs (both fixed and removable) has evolved tremendously over the last decade with the introduction of lithium-based batteries complementing lead-, nickel- and sodium-based technologies. These technologies will all continue to have a significant impact on electro-mobility as they may give cost and/or performance advantages for specific applications, for example as start-stop and hybrid solutions. The selection of a technology depends on the requirements for performance, life and cost for a given application. Given the diversity of possible operating modes, there is no one battery system or technology that covers the entire range of application needs sufficiently. On the contrary, different battery energy storage technologies exist and each of them has a role to play in the future as the best solution to the needs of a system depending on their specific attributes: * Lead-based: for start-stop micro application, up to mild HEVs * Nickel-based: for HEV applications only * Lithium-based: for HEV, plug-in HEV and full EVs * Sodium-based: for Plug-in HEV and full EVs