ac - Small power dc hybrid transmission for improving power system stability

The paper presents a novel FACTS concept to improve the dynamic stability of an ac power system. The concept of parallel ac/dc transmission between two ac systems has been exploited in the scheme presented, using one ac line for both the ac and the de transmission. A small unit of power is extracted from the system, converted to de and injected into the ac line through the transformer, neutrals at the two ends to enhance the dynamic stability. The objective of the paper is to introduce the new concept and prove its feasibility. To demonstrate the validity of the proposed method, computer simulated dynamic responses of an ac power system, with and without the controlled de injection are presented. It has been shown that by using about 2% of ac power transfer, as modulated de power, substantial system of damping could be achieved. (C) 2000 Elsevier Science S.A. All rights reserved.