Cooperative control between large capacity HVDC system and thermal power plant

This paper proposes a newly developed cooperative control scheme between an HVDC transmission system and a radially connected thermal power plant. The proposed control scheme aims at stable control of the generator frequency during and after the transition from at/de parallel connected operation to radially connected operation of the HVDC system and the thermal power plant due to loss of ac transmission. The advantage of the proposed control scheme is to minimize the loss of generation in the transition state by the high-speed cooperative control where control quantities, calculated based on the necessary data acquired prior to the occurrence of the loss of ac transmission, are applied. A prototype of the control equipment was manufactured and subjected to performance evaluation tests by means of a large-scale analog simulator. Keywords: HVDC, generator-HVDC radial system, PLU relay