Modeling and Analysis of Voltage Feasibility Problems for Cost-Effective Microgrids

Abstract

Global efforts to mitigate climate change have led to a significant increase in the integration of renewable energy resources into the electricity grid. This transition not only necessitates the adoption of renewable energy technologies but also requires rethinking and redesigning existing power grid infrastructures to accommodate the unique characteristics of these resources. This research focuses on modeling techniques which can assist in analyzing the feasibility of microgrid topologies. Microgrids have emerged as a flexible and efficient approach to implementing novel grid topologies that support higher levels of renewable energy penetration. They also support the integration of distributed energy resources (DERs), such as photovoltaic (PV) systems, thereby promoting a more sustainable and efficient energy grid design. This thesis utilized sanitized load and system topology data from a real world microgrid located in Illinois to test the feasibility of increasing the number of PV units the system can utilize for reactive power support.

In these systems, ensuring feasibility is a crucial concern due to power mismatches caused by the inherent variability of renewable resources. This work focuses of maintaining voltage within the constraints while increasing PV penetration on the system. We simulate the implementation of microgrids with PV generation using Alternating Current Optimal Power Flow (AC-OPF). The results of this thesis show the limits of feasible reactive power support from distributed PV units on a utility disconnected microgrid based on our voltage constraints. The study shows that there exists a limit to reactive power support provided by distributed PV units. Beyond this limit we see voltage collapse shown as infeasibility of power flow solutions. In order to avoid this problem we optimize the reactive power support from PV so that a solution exists within the constraints. The lesson learned for practical use of this result is that operators should use AC-OPF to compensate for reactive power using PV. Future research will explore the challenges and opportunities associated with the widespread adoption of microgrids, such as dynamic voltage instabilities that can occur with high levels of PV integration and complexities in inverter control strategies.