Analysis On Subsynchronous Oscillation By HVDC Based On EMTDC&RTDS

HVDC has more than 50 years of development history with many characteristics such as huge transmission ability, highly controllable, quick adjusting, and flexible operating. Because of its advantages, HVDC has been widely used in modern power system in long distance transmission, submarine transmission, regional power system connection and other kind of use. However, besides its economic and technical benefits, it also brings new challenges to power system operation. HVDC may cause sub-synchronous oscillation, and causes oscillation destroy to the generator shaft, which will affect the stability of power system. So analysis the characters of SSO caused by HVDC and design functional SSDC have important theoretical value and practical significance. Take one HVDC project as object of study, this thesis presents modeling, simulation and analysis of SSO with HVDC transmission line based on EMTDC and RTDS. Evaluate the risk of SSO both in island operation mode and AC/DC parallel operation mode, and whether the performance of SSDC meets the requirement. The results showed that in island operation mode SSO will never happen, but will happen in AC/DC parallel operation mode; Using TCSC instant of FSC can effectively damping the SSO; SSDC used in this project have a poor performance in AC/DC parallel operation mode. At last, based on simulation result the paper optimized the parameter of SSDC, the optimized SSDC increased the positive damping in the system and accelerate the rate of oscillation convergence.