Analysis of Subsynchronous Oscillation in the System Inteconnected with Offshore Wind farm by VSC-HVDC Based on Impedance Method

The offshore wind farm is interconnected to the Zhejiang power grid via the VSC-HVDC (voltage source converter-based high voltage direct current) lines, while there is a risk of subsynchronous oscillation for the wind farm transmission. This paper presents the phenomena of subsynchronous oscillation and analyzes it with impedance method, with a simplified system which contains offshore wind farm interconnected with VSC-HVDC. First, the corresponding electromagnetic transient model is built in PSCAD/EMTDC. And then, the subsynchronous oscillation phenomena in the proposed model is presented, and the characteric of the SSO is analyzed with simulation. Furthermore, the impedance modeling of the system is presented and the SSO is explained with the impendance method.