Implementation of a dedicated control to limit adverse interaction in multi-vendor HVDC systems

This paper reports on recent work performed in the framework of European project Best Paths DEMO #2, where interoperability in multi-vendor VSC-HVDC systems is investigated. In this four-year project, three major HVDC suppliers provided detailed EMT models which implement their state-of-the-art VSC technology in order to comply with realistic requirements and test cases provided by European TSOs and academics. Those models were used to perform interoperability studies and assess to what extent available technology is interoperable between various competitors. This paper provides the definition of ‘interoperability’ as agreed among the various stakeholders and describes the methodology used in the project for its assessment. It also reports on the results observed using detailed EMT converter models provided by the vendors, some of which exhibiting interoperability issues. In particular, some oscillatory behaviours were observed for which no satisfactory fix could be implemented directly in the converter models. Therefore, an innovative solution was implemented and tested, based on a DC-side Power Oscillation Damping (POD) control implemented in a third-party control in charge of the coordination of the converters; this proved to be most beneficial and finally limited the impact of those interoperability issues. Finally, the relevance and practical implementation of this solution is discussed and compared to direct adaptations in the converters themselves.