Study on the Influence of HVDC to Low Frequency Oscillation in Interconnected Power System

With the development of UHV AC/DC hybrid power system in China, the power oscillation phenomena of the large inter-area mode are often observed in the daily operation of UHV AC transmission line. With huge economic benefits gained through HVDC transmission, the HVDC transmission also has an important impact on AC system damping characteristics and power oscillation. The power oscillation has become a serious threat to the safe and stable operation of UHV power grid. Thus, strengthening the research of HVDC is very meaningful. This paper focuses on the oscillation energy function of power system which contains HVDC transmission. Based on the analysis of multi-machine system, the oscillation energy characteristics are presented along with the low frequency oscillation of AC/DC hybrid power system, and the main factors affecting the oscillation energy of HVDC transmission system are obtained. Finally, a four-machine two-zone AC/DC hybrid system was built. The simulation results of low frequency oscillation energy in interconnected power system with HVDC transmission access verify the accuracy of the analysis.