On the Limitations of Using a LTI Modelling Approach for Control Tuning of VSC-HVDC Systems

This paper investigates the tuning methods of a High Voltage Direct Current (HVDC) Voltage Sourced Converter (VSC) system using double dq synchronous rotating reference frames. This work shows, and confirms by simulation results, that commonly used Linear Time-Invariant (LTI) tuning methods may lead to undesired behaviours when the underlying system is Linear Time-Periodic (LTP). In order to find the optimal tuning parameters, LTP system has been tuned using a machine learning method called Gradient Descent. As a result of this work, new LTP-based tuning methods may be used in the field of VSC-HVDC control.