As more HVDC links are commissioned and built in the North Sea, it may become desirable to interconnect adjacent links in the future. This research focuses on using DC technology to make these interconnections. To begin with DC/DC converters suited for use in these connections were investigated [1]. These converters would allow DC systems of differing voltage and technology to be interconnected. This converters can also block DC side faults, depending on the topology.  This research involved detailed study of a resonant DC/DC converter topology and comparison with other converter topologies [2].

Following from this, reduced dynamic models of modular multilevel converters were developed in MATLAB, Simulink to enable computationally efficient and accurate system level simulations [3]. These reduced models allow time efficient simulation of complex system while maintaining accurate converter dynamics.

Research is now focused on investigating an offshore DC grid scenario using the Dogger Bank Round 3 zone as the case study area, shown in the figure below. A connection between Dogger Bank and the proposed UK-Norway link will also be studied. This scenario will use the library of models developed throughout the PhD to allow a simulation based study along with an analytical study.


CAP People

  • C. E. Sheridan (
  • Dr M. M. C. Merlin (
  • Prof. T. C. Green (



[1]. Sheridan, C. E., Merlin, M. M. C., & Green, T. C. (2012). Assessment of DC / DC Converters for use in DC Nodes for Offshore Grids. In 10th IET International Conference on AC and DC Power Transmission (ACDC 2012) (pp. 1–6). Birmingham.

[2]. Sheridan, C. E., Merlin, M. M. C., & Green, T. C. (2013). Study of a Resonant DC / DC Converter in Alternate Discontinuous Mode. In Power and Energy Society General Meeting (PES), 2013 IEEE. Vancouver.

[3]. Sheridan, C. E., Merlin, M. M. C., & Green, T. C. (2014). Reduced Dynamic Model of the Alternate Arm Converter. In Control and Modeling for Power Electronics (COMPEL), 2014 IEEE 15th Workshop on. Santander.