D.2.2 – Now available to explore!

The first version of the report “Grid-forming Functional Requirements for HVDC Converter Stations and DC-connected Power Park Modules in Multi-Terminal Multi-Vendor HVDC Systems” is out!

This report presents the project stakeholders’ view on these requirements. It will be used as a basis for the demonstration design as well as the selection of the test protocol and verification process.

Main findings:

  • The functional requirements are based on the voltage source behind an impedance definition, which is found to be the most prominent functional definition by the industry state-of-the-art.
  • The grid-forming functionality is sub-divided into 5 core capabilities which the converter must have as long as it is within its voltage, frequency and energy limits
  • Four different use cases of how grid-forming control could be applied in an HVDC system with and without support from the wind power plants is proposed.
  • The importance of coordinating grid-forming control with DC voltage control is discussed and highlighted.
  • To enable grid-forming control in coordination with DC voltage control, HVDC converter stations must be able to have grid-forming and DC voltage droop control activated simultaneously.


 The main focus of the InterOPERA project is to enable multi-vendor HVDC systems that are mutually compatible and interoperable by design to support the green energy transition. However, as the green transition progresses the power system characteristics are changing as the system becomes more and more power electronic based. 

 In order to fully support this transition, it is important that multi-vendor HVDC systems do not adversely impact the strength of the power system, but rather has the capability to improve the overall robustness and stability.

 For this reason, demonstrating grid-forming control by multi-vendor HVDC systems is an integral part of the InterOPERA project.  As a starting point, InterOPERA has now developed the basic functional requirements for grid-forming control of HVDC converter stations and HVDC system connected wind power plants in the multi-vendor HVDC system. These functional requirements will lay the basis for detailed design and control implementation in InterOPERA.

 The basic functionalities are well aligned with ongoing grid-forming work in other areas but is extended with considerations of how to coordinate grid-forming control with the DC voltage control in HVDC systems.

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