Improved control of multi terminal direct current voltage source converters using proportional integral and lead lag controllers

In this study, control methods for the converter inner current loop of HVDC systems were evaluated by comparing different combinations of PI controllers and lead-lag compensators. The evaluation was performed on a 3-terminal voltage source converter (VSC)-based multi-terminal direct current (MTDC) system using PSCAD/EMTDC transient analysis simulation. The performance was analyzed under three fault conditions. (alternating current) AC-side single line-to-ground fault, (direct current) DC transmission line fault, and converter disconnection). The results showed that connecting a PI controller to the DC link voltage stabilizer and lead-lag compensators to the power source and load achieved optimal performance with an average overshoot of 78% and an average stabilization time of 398 msec. This represents a 26% reduction in settling time and a 42% increase in overshoot compared to the generic PI controller. The performance was compared by scoring and found to be a 40% increase in control performance. This study demonstrates that lead-lag compensators can significantly improve the control performance of VSC-based MTDC systems.