Innovative Power Hardware-in-the-Loop Testing Methods for Advanced Grid-Forming Inverters using Rapid Control Prototyping

Abstract:
As the energy transition progresses and generation units become more decentralized, the grid-forming capabilities of inverters are gaining importance in the energy supply system. Although grid-forming inverters have been researched for some time, newly developed features add complexity to the testing framework. The design of the test grid is critical for ensuring accurate and reliable test results. This publication demonstrates how Rapid Control Prototyping (RCP) and Power Hardware-in-the-Loop (P-HiL) techniques create flexible test structures in the laboratory. It starts by presenting the RCP and P-HiL inverter used. Following that, it shows how the device merges both RCP and P-HiL functionalities and how the development environment supports rapid transition from concept to validation of innovative inverter control strategies. The focus then shifts to the grid-forming function under test, specifically the interaction between two grid-forming inverters. A microgrid serves as the test grid string, equipped with the RCP inverter and the P-HiL setup. The inverter uses a grid-forming control system to supply the test grid string, where real loads are connected. The P-HiL setup emulates a microgrid through a real-time computer, connected to the real test grid string via the P-HiL amplifier. This example highlights the synchronization process, load sharing, and the essential use of grid-forming features. The labora-tory test implementation is shown with the RCP inverter and P-HiL amplifier. The flexible test setup is detailed, and the approach's advantages are visualized. An analysis of the test results is then performed, showcasing how the grid-forming control responds during load sharing and synchronization. Finally, the results and test setup are discussed, presenting the key findings from the test.