Graduation Date
Summer 2024
Document Type
Thesis
Program
Master of Science degree with a major in Environmental Systems, option Energy, Technology, and Policy
Committee Chair Name
Dr. Peter Alstone
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Dr. Arne Jacobson
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Dr. William V Fisher
Third Committee Member Affiliation
HSU Faculty or Staff
Sixth Committee Member Affiliation
HSU Faculty or Staff
Keywords
Microgrids, AC coupled, DC coupled, Solar PV, Energy storage, Electrical performance, Economic analysis, Renewable energy, Clean energy
Subject Categories
Environmental Systems
Abstract
This study compares the electrical performance and economics of DC-coupled and AC-coupled community microgrid configurations through simulation and financial modeling of the Redwood Coast Airport Microgrid (RCAM), which integrates 2.2 MW of solar PV and 2.2 MW of battery storage. Unified load flow, short circuit, transient stability (including load impact), and efficiency studies using ETAP & SAM software tools demonstrate that the DC-coupled configuration is preferred based on efficiency, while both configurations exhibit equivalent performance with respect to selected power quality metrics. The DC setup exhibits 11% higher overall efficiency than AC coupling in converting solar energy to grid exports. Both configurations have similar short circuit current levels and transient stability characteristics, with the AC system remaining stable under higher load impacts of up to 600% compared to 400% for DC coupling.
Economically, the AC- and DC-coupled systems have nearly identical upfront capital costs (~$10.8 million), but the DC configuration involves greater risks due to the immaturity of DC-DC converter technology. The DC option's marginally higher levelized cost of energy (LCOE) at $0.25/kWh, compared to $0.24/kWh for the AC configuration, is due to the higher O&M cost associated with the DC configuration. A sensitivity analysis reveals that the DC configuration would achieve a positive net present value at a slightly lower solar PPA price compared to the AC system.
Considering the current technological maturity and cost risks, this study recommends AC-coupled architectures for short-term deployment of community-scale PV plus storage microgrids. However, the DC configuration's higher efficiency highlights the need for continued research and development. In the long run, with advancements in DC technology, DC-coupled architectures could become a reliable and cost-effective option for microgrid design.
Citation Style
APA
Recommended Citation
Kumar, Sanjeev, "Comparative analysis of ac coupled and dc coupled microgrids: analyzing electrical performances and economics" (2024). Cal Poly Humboldt theses and projects. 788.
https://digitalcommons.humboldt.edu/etd/788