In a significant stride towards enhancing grid stability and reliability, researchers have developed an impedance-based method for predictive stability assessment in decentralized converter-based power plants. This innovative approach, presented by Johannes Schräder from Helmut Schmidt University at the Future Power Grids Conference, promises to revolutionize the way we assess harmonic stability in power grids, particularly those with high penetration of power electronics-coupled systems.
The conventional compliance testing during the grid connection process often falls short in providing a specific and timely foundation for assessing harmonic stability. Schräder’s research introduces an impedance-based analysis method that addresses these limitations. “By implementing black-box model approaches, we can assess harmonic stability without the need to disclose internal control models,” Schräder explains. This method initially requires only the knowledge of the input impedances of the planned grid connection point and the planned PV system.
One of the key components of this method is impedance spectroscopy for inverters. This technique allows for the determination of the effective impedance profile and the internal harmonic sources of inverters, enabling the description of the frequency-dependent behavior of individual units. Additionally, the time- and frequency-dependent grid impedance at the grid connection point (GCP) has been successfully measured in several campaigns on medium and low-voltage grids.
The coordinated application of these measurement methods paves the way for predictive harmonic assessment. This ensures high planning reliability and grid quality, even in grids with a high penetration of power electronics-coupled systems. As Schräder notes, “This method provides a more specific and earlier foundation for assessing harmonic stability, which is crucial for the future of our power grids.”
The research, published in the Proceedings of the Future Power Grids Conference, provides an overview of the current state of research on impedance-based stability criteria and presents measurement methods for practical implementation. It also outlines the remaining open questions until application in the field.
The implications of this research are far-reaching for the energy sector. As the penetration of renewable energy sources continues to grow, the need for stable and reliable grids becomes increasingly critical. This impedance-based method offers a promising solution, ensuring that grids can accommodate high levels of power electronics-coupled systems without compromising stability or quality.
In the words of Schräder, “This method is a significant step forward in our quest for a more stable and reliable grid. It provides a robust tool for predictive assessment, enabling us to plan and operate our grids with greater confidence.” As the energy sector continues to evolve, such innovations will be crucial in shaping the future of our power grids.