Increasing the SSO Damping Effectiveness of IMDU by Raising Its Operating Frequency and Optimizing Its Parameters

In this paper, it is shown that analyzing the subsynchronous oscillation (SSO) damping effectiveness of an induction machine damping unit (IMDU) only based on its torque-slip characteristic curve is not adequate. A method to directly calculate the electrical damping of an IMDU according to its parameters, which is fast and accurate, is developed. This direct calculation method makes it possible to carry out parameter optimization of the IMDU by genetic algorithms. This paper also demonstrates that the electrical damping of IMDU in the subsynchronous frequency range can be significantly increased by raising its rated frequency. In addition, the voltage-source inverter used to drive the IMDU and raise the frequency can provide a constant magnitude terminal voltage for the IMDU during disturbances. The SSO damping effectiveness of the IMDU after parameter optimization and frequency raise is verified by eigenvalue analysis, electrical damping analysis and time-domain simulation.