Abstract :
The valve, which blocks and conducts current periodically, is truly the heart of HVdc. There were complex factors associated with mercury-arc valves that didn´t permit the precise prediction of its performance, whereas the performance of thyristor valves can be predicted with remarkable accuracy. The advances in the solid-state valve have made HVdc economically much more competitive. As a consequence, more and more HVdc links have been commissioned, and many more are being planned throughout the world. There is an unending requirement for improving the thyristor valve. It calls for larger capacity thyristors, lower losses, lower maintenance, and higher reliability. The use of power electronics in power systems is increasing significantly with thyristor capability. In the future, ac-dc combinations will make the most efficient use of renewable energy without affecting the environment. Silicon is the best medium for the conditioning of electrical power into usable form. It is extraordinarily stable and has long life when processed and used properly.
