Cross Vendor Measurements of Grid Forming Converters to Analyze the State of the Art

To achieve the goals for emission reduction, renewable and storage power plants must, alongside expanding the generation, provide extensive system services and essential properties—such as the formation of the grid—to ensure stable system operation at all times.

New verification methods are required to confirm that grid-forming behavior meets stability requirements under all grid conditions. Fraunhofer ISE, together with its partners, has developed and tested such a method using various grid-forming devices. This has enabled both optimizations of the verification process and a comprehensive market overview of current grid-forming inverter technology.

Initial Situation

In today’s power grid, essential properties for stable operation—providing voltage with stable amplitude and frequency—are nearly exclusively delivered by conventional large-scale power plants.

It is now widely accepted that achieving climate goals requires, alongside expanding renewable generation, the installation of significant grid-forming inverter capacity to ensure system stability. These systems must have grid-forming capabilities like voltage source behavior. However, planned fully integrated grid components (e.g. HVDC, STATCOM, etc.) with grid-forming capabilities by transmission system operators (TSOs) are insufficient to meet future demand. Consequently, customer installations must contribute significantly to providing these capabilities.

The lack of clear guidelines for the  dynamic behavior of grid-forming units has led to flexibility in implementation and parameterization by the manufacturer. Additionally, no universal verification method exists to validate grid-forming capabilities.

Objective

To address this, the project aims to provide an overview of grid-forming converter behavior and manufacturer-specific implementation interpretations. It pursues three goals:

1. Analyze the current state of technology regarding performance and implementation of grid-forming inverters.
2. Collect comprehensively experienc and insights on verification and conformity testing of grid-forming converter behavior.
3. Identify necessary development potential for grid-forming inverters to enhance system stabilization.

Approach

Measurements will be conducted with a wide range of devices from participating manufacturers. To enable cross-comparison, the project will first develop a standardized measurement and evaluation procedure, along with a requirements catalog, in collaboration with TSOs (50Hertz Transmission GmbH, Amprion GmbH, Tennet TSO GmbH, TransnetBW GmbH) and participating converter manufacturers. Results will be presented to the technical community through dedicated workshops.