Modeling and Voltage Characteristic Analysis of UHV AC-DC Interconnection System

In order to further meet the outbound demand of large energy bases in China and optimize the distribution of energy in large regions, China's ultra-high voltage power grid has entered the phase of large-scale construction. The access of large-capacity UHVDC makes the safety and stability characteristics of delivery system, the structure characteristics and system operation control of power grid are more complex, which increases the risk of security and stability. In this context, this paper researches the problem of complex interaction between UHV DC system and new energy plant station at the sending end, and the voltage fluctuation of UHV DC system caused by the high percentage of new energy access. In this paper, the main work is to consider the response characteristics of UHV AC/DC system after failure, analyze the coupling characteristics of generators, loads, governors and other equipment, and establish UHV AC/DC system model. Meanwhile, taking Liaoning UHV DC input network as a research object, the voltage characteristics of AC system under N-1 fault and DC lock fault are analyzed.