Stability Assessment and Mitigation of Converter Interactions – Phase 2

Executive Summary

The proposed project builds on the previous work done by the University of Strathclyde for the National HVDC centre on the development of small-signal impedance model of MMC converter and its use for assessing multi-converter interactions. The project will concentrate on developing further converter models for stability analysis of complex networks with significant converter presence. The development of analytical impedance model can provide further insight into the impact of circuit and control structure / parameters on system impedance. This will give confidence that the frequency sweep method can extract the correct frequency-dependent characteristic and also provide good understanding of the influence of different parts (circuit, control structure, parameter etc.) in the converter system on impedance.

The following tasks are envisaged:

  • Develop and validate the approach for frequency-dependent impedance model of LCC HVDC system;
  • Develop and validate the frequency-dependent impedance models of type-4 wind turbines with typical power control strategy; and
  • Cross-validation of the frequency-dependent models with the impedance measurement from EMT models developed using real time simulation software, RSCAD.