By 2030, a significant level of Inverter Based Resources (IBRs) will be installed in the GB transmission system. Grid forming control (GFM) of power electronic converters, which emulate synchronous generators, is an effective approach to address low inertia and fault level challenges in systems with high IBR penetration. GFM converters operate as internal voltage sources, mimicking traditional synchronous generators. However, the rollout of GFMs in the GB network may cause negative interactions with Grid Following (GFL) and Synchronous Generators. This project will analyze these interactions, especially those newly introduced by GFMs, and provide analytical methods and guidelines to mitigate potential risks, contributing to NESO’s policy and strategy for GFM implementation.
Benefits
- Benefit 1: The project will provide understandings of the interactions between GFM, GFL and Synchronous Generators especially newly introduced interactions by GFMs.
- Benefit 2: The project will provide analytical and testing method of the potential negative interaction risks between IBRs.
- Benefit 3: The project will provide analysis and testing guidelines to avoid the negative interaction risks between GFMs to support the operational and planning approach involving IBRs especially GFMs based resources.
- Benefit 4: The outcome of the project will contribute to NESO’s development of policy and strategy of stability control services using GFM.
- Benefit 5: The project will support the digital transition by introducing the design procedure for rolling out GFMs and hence speed up the IBRs integration.
Learnings
Outcomes
The current outcomes of the project are summarised as follows:
> WP1 has delivered detailed EMT models for SGs, SynCons, GFL PVs, GFL WFs, GFM BESSs and GFM WFs.
> Three benchmark test systems have been established for interaction studies.
> FRT tests have been conducted to validate the stability of the established test systems.
> Comparative analysis has been completed to identify key interaction-related differences between SGs, GFL IBRs and GFM IBRs.
> WP2 works have identified some control interaction risks between GFMs, GFLs and the GB electricity grid and the interactions between local GFMs. Further study to identify a broader range of interaction scenarios are still in progress.
> The frequency scan technique has been implemented in PSCAD.
> A methodology for whole-system stability analysis tools has been developed.
These outcomes provide the technical foundation for developing interaction analysis methods and future mitigation guidance.
The project generated the following key deliverables:
> GFM Interaction WP1 Report
Lessons Learnt
Throughout the ongoing project, several key lessons have emerged that will benefit future projects.
One important lesson is the need to define modelling requirements in line with realistic GB network conditions at an early stage. During the model development period, NESO required EMT models of key power system components, including GFM BESS, GFL PV and SynCons, to reflect representative GB network conditions. This has highlighted the importance of agreeing modelling assumptions, component specifications and validation requirements early in the project to improve model relevance and reduce the need for later refinement.
Another lesson is the importance of focusing on control interactions introduced by GFM-controlled IBRs. As GFM technologies are expected to play an increasing role in future low-inertia power systems, their control behavior may introduce new interaction risks with GFL IBRs, synchronous generators and other local GFMs. Future projects should therefore explicitly include control interaction studies in the project scope, particularly under different system strength, topology and disturbance conditions.
These lessons highlight the importance of early technical alignment, realistic model development and targeted assessment of GFM-related control interactions. By applying these insights, future projects can be better prepared to identify interaction risks, define suitable study methods and develop effective mitigation approaches.
