Advanced decision support for operation of converter-dominated grids with low inertia utilizing a modular development and testing framework

To master this new complexity in the control room, there is a need for advanced decision-support tools and a new generation of dynamic security-assessment methods. To be able to develop advanced algorithms, methods and products, the system dynamics and novel system properties have to be emulated realistically including all relevant risks introduced by control converters in an adequate and modular way.

Within the German public funded project “Online Dynamic Security Assessment for Low Inertia

Power Systems” (LI-SA), the introduced challenges are addressed and a modular development and testing framework as well as advanced decision support for converter-dominated grids with low inertia are realized, demonstrated and assessed. This paper presents the results of the three-year project, including the concepts developed and implemented, the key takeaways and lessons learned, and recommendations for advanced decision support and for testing frameworks. The following topics are discussed in more detail.

A modular development and testing framework is designed and realized as a demonstrator. The fundament is a digital real-time twin operating with microsecond resolution which is utilized to generate emulated measurement data for future grid systems including conventional as well as power-electronic converters covering even pulse-pattern generation relevant for harmonic stability and electromagnetic compatibility (EMC). A special focus is the flexibility and modularity for structure and systems to be emulated. Based on digital quasi-analogue simulation of the system, the high-resolution data is aggregated – like in real applications – by phasor-measurement units and more advanced decentralized measurement units. The measurement-data collection is done by an industrial gridcontrol system hosted in the Kubernetes Cluster. The data is transmitted via IEEE C371 synchro-phasor protocol. Additional measurements are provided via IEC 61850

Manufacturing Message Specification (MMS)2.

Within this Kubernetes Cluster, typical state estimation methods as well as converteradequate grid-calculation methods – like e.g. electromagnetic transients (EMT) grid calculations – are executed for dynamic-security methods. Based on this measured and estimated data, different decision support functions are executed.

The demonstrator is commissioned with the basic IEEE 9-bus-system modified from the parameters to a typical 380-kV European transmission system operator (TSO) grid section.

Additionally, the integrated assets are varied to showcase stability risks driven by converters.

The second pillar of the of the project is the specific method development for decision support focussing on inertia estimation. Different approaches are implemented by different partners and the performance assessed within the introduced development and testing framework.

A modular framework is realized and demonstrated which can be adapted to any future grid structure, any communication protocol and any converter controls. This allows for developing and reliant testing of decision support, modern state estimation and dynamic security assessment (DSA) methods.