Dual-Channel Subsynchronous Damping Control based on Voltage Source Converter Excitation System

A novel dual-channel damping control based on voltage source converter (VSC) excitation system is put forward in this paper to suppress subsynchronous oscillation for turbine generators. The proposed control is a combination of both supplementary excitation damping control (SEDC) and supplementary subsynchronous damping control (SSDC) but only implemented in one device. A small perturbation linearized model considering the dual-channel damping is built and the complex torque coefficients method is adopted to analyze the damping characteristic of the proposed control. Based on the analytical analysis, a decoupling tuning method for the dual-channel damping control is proposed. The effectiveness and superiority of the proposed subsynchronous damping control are verified through PSCAD simulation.