Operational concepts for offgrids and weak grids are a major challenge in general but especially in case of converter domination. The energy transition world-wide results in different offgrids, microgrids and weak grid situations which share the characteristic and related challenges of converter domination. Beside other aspects, the lack of energy-buffering inertia as well as instantaneous stability and interactions between controlled converters can be identified as key challenges.

In order to design a resilient operational concept, the fundamental design rule of power-system backbones have to be taken into account: explicit communication is only allowed to optimize the loadflow – in case of any disturbance in communication, the power system has to operate in a stable manner. This golden rule is even more relevant nowadays due to extended risk of cyber security issues. Today, ever so often communication is defined es central aspect for a resilient smart grid or any other grid configuration which includes a high unnecessary risk due to possible cyber attacks.

Within this paper, a resilient operational concept is presented which is compatible with grid-forming properties and fulfils the introduced control rule of power-system backbone design. A further novelty is the fact that also dynamic infeed-sharing can be parametrized easily which is essential for any weak-configuration in hybrid constellations with e.g. BESS. The performance of the operational principal is verified in different challenging scenarios including different converter dimensioning in detailed EMT-based grid calculations. The performed study will analyse typical fault and stability scenarios and will also include a detailed protection analysis specifically for the converter-dominated grid. The scenarios will include the emulation of communication failures and cyber-security intrusions. This is crucial for any new operational-concept proposal. Furthermore, the implementation is verified by HIL analysis and comparison of a laboratory measurement of a subset of the system analysis. The final paper will include all utilized framework, digital twin and laboratory components enabling the detailed analysis of the introduced concepts.