A general control system structure for multi-terminal VSC-HVDC systems

Renewable technology expands geographically and in capacity. The long transmission distance and bulk power transfer involved make multi-terminal VSC-HVDC systems a key technology for future power systems. This expansion could be hampered by the pace of development of multi-terminal systems especially when standardization is not reached in hardware or the control system. A general control system structure is proposed in this paper, dividing the control system in control levels for primary and secondary control implementation and focusing on the interface among them for modularity and expandability. Uniform interfaces standardize data exchange and decouple the overall system control from the local substation control. A version of the control system is tested on a simplified model for different scenarios and number of terminals to demonstrate its functionality and ability to integrate additional terminals. The control system structure provides a platform where each part of the control system can be programmed independently.