A Method to Design a Subsynchronous Damping Controller for HVDC Transmission System

Subsynchronous damping controller (SSDC) is an effective countermeasure to attenuate the subsynchronous oscillation (SSO) caused by HVDC transmission.On the basis of analyzing the mechanism of inducing SSO by HVDC transmission, the principle of attenuating SSO is expounded;and then based on the principle of phase compensation, a method to design SSDC according to the principle of phase compensation is proposed.The proposed method possesses clear physical conception and is convenient to implement.Combining IEEE SSR first benchmark model with CIGRE benchmark model, a test system for the research on the inducing SSO by HVDC transmission is built.The calculation results of electrical damping of this test system show that controlled by the designed SSDC, the electrical negative damping decreases greatly, and the electrical positive damping increases within subsynchronous frequency band;under appropriate proportional coefficient, all of the electrical damping are positive.Time domain simulation results validate the effectiveness of the designed SSDC.