Research on Resonance Problem of DC Feed in AC System

In order to analyze the resonance problem of the DC fed AC system, an oscillation risk analysis method based on s-domain node admittance array is proposed. Based on the equivalent AC network structure, this paper proposes a method to generate the s-domain node admittance matrix of the system based on the node admittance matrix of the power frequency equivalent circuit of the system, and then obtains the resonance mode of the system; Then, based on this, the sensitivity model of the oscillation risk of the AC component parameters in the system resonance mode is constructed, and the sensitivity relationship between the component parameters and the resonance mode in the oscillation frequency range is studied, which can predict the oscillation risk of the DC fed AC system; Finally, the LCC feeding three machine nine node system model is built on PSCAD/EMTDC platform and verified by simulation. The simulation results verify the correctness and effectiveness of the proposed sensitivity analysis method.