Analysis of the Impact of HVDC Frequency Control Parameters on HVDC Power Oscillation and Interarea Oscillation

Controlling the DC power of High-Voltage Direct Current (HVDC) systems that interconnect two asynchronously grids can improve the frequency stability of asynchronously interconnected systems. The use of HVDC systems in frequency support has been studied in previous research, with numerous practical applications. However, the interaction between HVDC power control (due to frequency support) and interarea oscillation in asynchronous AC grids has not been discussed in previous studies. To investigate this issue, a detailed small signal model considering the HVDC system with bilateral frequency control has been developed, and corresponding modal analysis is conducted. Based on the developed model, the interaction between HVDC power oscillations and interarea oscillations, as well as the influence of HVDC frequency control parameters on these oscillations, has been analyzed. The performance of the analysis is then demonstrated through simulations on a modified eight-generator two-area system. Additionally, the effect of the dead-band on HVDC power oscillation dynamics, a topic previously unreported, is presented.