Grid-Code Certification by Simulation for Grid-Forming Connected Inverters

Abstract

The increasing penetration of inverter-based resources is transforming modern power systems and creating new challenges for grid-code compliance, particularly for voltage formation and frequency stability. This thesis investigates how simulation-based evidence can support the verification of grid-forming inverter behaviour according to selected requirements of the VDE FNN guideline Technical Requirements for Grid-Forming Capabilities Including Provision of Inertia. The study focuses on two core requirements: voltage-source behaviour and Primary Control Based on Network Security (PCNB).

An electromagnetic transient model of a grid-forming inverter is implemented in MATLAB/Simulink and evaluated through the Automatic GFM Inverter Simulator (AGIS), a framework developed to automate selected virtual-island tests, extract active power, reactive power, voltage and frequency, calculate deviations, and generate structured validation reports. Two scenarios are analysed: a baseline non-compliant configuration and a tuned configuration. The results show that AGIS can distinguish between non-compliant and compliant behaviour and provide repeatable, traceable evidence for the selected verification procedures. Overall, the thesis demonstrates that automated EMT-based simulation can support structured grid-code verification for grid-forming inverter models, while recognising that hardware-based validation remains necessary for full certification.