A frequency-dependent virtual impedance approach to improving stability with grid-forming inverters

Simple item page
dc.contributor.authorUnruh, Lukas
dc.contributor.examiningcommitteeGole, Aniruddha (Electrical and Computer Engineering)
dc.contributor.examiningcommitteeFilizadeh, Shaahin (Electrical and Computer Engineering)
dc.contributor.supervisorAnnakkage, Udaya
dc.date.accessioned2025-03-11T17:44:33Z
dc.date.available2025-03-11T17:44:33Z
dc.date.issued2025-03-11
dc.date.submitted2025-03-09T19:59:42Zen_US
dc.date.submitted2025-03-11T16:25:44Zen_US
dc.degree.disciplineElectrical and Computer Engineering
dc.degree.levelMaster of Science (M.Sc.)
dc.description.abstractGrid-forming inverters have gained significant attention for their ability to improve stability in weak and islanded power systems; however, the full extent of their potential benefits for the future bulk power system remains uncertain. One potential benefit is increasing stability margins in regions affected by inverter-driven instabilities, such as series-compensated areas within the ERCOT system. This thesis explores their potential in mitigating Wind Sub-Synchronous Control Oscillations (W-SSCI) in series-compensated systems with Type-3 wind plants when a grid-forming configured battery plant is co-located with the wind plant. A novel frequency-dependent virtual impedance (FDVI) controller is proposed to improve the performance of grid-forming battery energy storage systems (BESS). Comparative analyses of grid-forming and grid-following inverters are performed to evaluate their damping capabilities. This thesis includes the development and verification of models in EMTDC/PSCAD, incorporates impedance scanning, eigenvalue analysis, and time-domain simulations, with the objective of quantifying the minimum capacity of grid-forming BESS needed to provide stability. The results indicate that grid-forming BESS can provide substantial damping to mitigate W-SSCI, even under severe series compensation scenarios. The FDVI controller further reduces the required BESS capacity by up to 45\%, demonstrating improved stability through targeted conductance tuning. Conversely, grid-following BESS inverters are found to be unsuitable for W-SSCI mitigation because of their low admittance at sub-synchronous frequencies and susceptibility to instability under high gains or large BESS ratings. The findings strongly support the adoption of grid-forming inverters as a cost-effective solution for stability-constrained regions, offering superior damping performance compared to conventional technologies.
dc.description.noteMay 2025
dc.identifier.urihttp://hdl.handle.net/1993/38922
dc.language.isoeng
dc.subjectgrid-forming inverters
dc.subjectsub-synchronous control interactions
dc.subjectinverter-based resources
dc.subjectvirtual impedance
dc.subjectpower system stability
dc.titleA frequency-dependent virtual impedance approach to improving stability with grid-forming inverters
local.subject.manitobano
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Unruh_Lukas.pdf
Size:
1.92 MB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
770 B
Format:
Item-specific license agreed to upon submission
Description:
Download
Collections
FGS - Electronic Theses and Practica