EMT-Based Analysis of Supraharmonic Emission and Propagation in IBRs and Data Centers Dominated Power Systems

The rapid proliferation of inverter-based resources (IBRs) and artificial intelligence (AI) data centers has made supraharmonics a growing concern in modern power systems. Supraharmonics originate from high-frequency switching in converters and nonlinear loads, leading to equipment malfunction, overheating, and protection misoperations. This study highlights the limitations of conventional phasor measurement units (PMUs), which are incapable of capturing high-frequency supraharmonics, and emphasizes the necessity of high-resolution waveform measurement units (WMUs) for accurate monitoring. Detailed electromagnetic transient (EMT) simulations are conducted using a modified IEEE 9-bus system integrated with an IEEE 4-node distribution network to investigate the emission, propagation, and attenuation characteristics of supraharmonics. The results show that supraharmonics appear as spectral sidebands around converter switching frequencies and are highly sensitive to system impedance and transformer coupling. Lower-frequency components propagate with minimal loss, whereas higher-frequency components experience strong attenuation across transformers. Transmission line parameters such as inductance, susceptance, and length significantly influence supraharmonic propagation, and resonance phenomena may occur at specific frequencies due to the line's travelingwave characteristics. The insights from this research provide a foundation for developing effective mitigation strategies and future regulatory frameworks to manage supraharmonics in modern power systems.