Author ORCID Identifier
0000-0003-1324-0022
Document Type
Dissertation
Date of Award
5-31-2024
Degree Name
Doctor of Philosophy in Electrical Engineering - (Ph.D.)
Department
Electrical and Computer Engineering
First Advisor
Seyyedmohsen Azizi
Second Advisor
Moshe Kam
Third Advisor
Nirwan Ansari
Fourth Advisor
MengChu Zhou
Fifth Advisor
Zhiming Ji
Sixth Advisor
Cong Wang
Abstract
As the global community struggles with the escalating challenges of climate change and environmental degradation, the transition to renewable energy sources has emerged as a paramount solution. Harnessing energy from renewable sources such as solar, wind, and hydro power not only alleviates the adverse effects of conventional fossil fuel energy sources, but also establishes a foundation for a sustainable and resilient future. Microgrids have been utilized as a feasible platform to integrate renewable energy sources into the electrical power generation networks. They include one or more generation units connected to nearby users, and are able to operate in both grid-connected and stand-alone modes.
In recent years, small-scale microgrids have become popular for their capability to provide off-grid electrical power generation platforms. However, due to the short distances among generation systems in small-scale microgrids, the coupling dynamics among them strengthens considerably, which endangers the system stability. In addition, low-inertial power electronic modules used in renewable energy systems worsen the aforementioned instability problem. In this dissertation, decentralized retrofit model predictive controllers are proposed to address the above-mentioned instability issue for the microgrids that have distances in the range of 200 (m) ?800 (m) among their inverters. Moreover, sequentially-designed decentralized robust controllers are proposed to stabilize the microgrids with distances less than 200 (m) among their inverters.
Hybrid AC/DC microgrids have also become popular in recent years due to their combined advantages from both AC and DC microgrids. One of the salient challenges in such systems is to mitigate the issue of instability due to high AC load demands. In this dissertation, a novel model predictive control scheme is proposed to compensate for the poor performance of the existing conventional power sharing droop controllers. The proposed controller minimizes the active power difference between the DC and AC microgrids by transferring more power from the DC to AC microgrid.
Stand-alone wind-diesel generator systems are hybrid systems that utilize two energy resources. These systems are most suitable for remote and isolated areas such as rural places in Alaska, where the power grid is not always available. In such stand-alone systems, the irregular nature of wind power, sudden changes of load demands, and system parameter uncertainties are critical issues specifically in the absence of the power grid. These disturbances and uncertainties make the frequency and active power deviate from their nominal values. Therefore, advanced robust controllers based on ?-synthesis technique are proposed in this dissertation to ensure smooth frequency and active power transients in the presence of disturbances in the load and wind powers, and system parameter variations.
Recommended Citation
Shojaee, Milad, "Decentralized control of renewable generation systems" (2024). Dissertations. 1760.
https://digitalcommons.njit.edu/dissertations/1760
