Browsing by Author "Gray, Matt"

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Analysis and evaluation of transactive energy control in active distribution systems
(2016-10-01) Gray, Matt; Ibrahim, Walid Morsi
The electric power distribution system is experiencing significant operational changes due to the integration of plug-in electric vehicles and intermittent distributed energy resources such as rooftop solar photovoltaics. As plug-in electric vehicle charging represents a significant increase in system loading, both distribution transformers and substation transformers are subject to overload conditions which rapidly degrade transformers lifetime. Furthermore, the increased penetration of rooftop solar photovoltaic in the residential sector may lead to bi-directional power flow and may additionally cause overload to the distribution transformers. In order to accommodate the growing market penetration of plug-in electric vehicles and rooftop solar photovoltaics, the electric utility must employ energy management to prolong the transformers lifetime. Given that transformers represent one of the most expensive assets in the distribution system, failure to resolve transformer lifetime degradation issues require the electric utility to incur the costs of transformer replacement or upgrading. The work in this dissertation proposes a transactive energy control methodology to perform residential energy storage system control as a means of reducing transformer lifetime degradation. The results have shown that the proposed framework may extend median annual distribution transformer lifetime by nearly double the expected lifetime of distribution transformers without transactive energy control. Finally, the proposed transactive control scheme has also been found to reduce active power losses within the system.
Probabilistic assessment of the impact of plug-in electric vehicles on power quality in electric vehicles on power quality in electric distribution systems.
(2013-11-01) Gray, Matt; Ibrahim, Walid Morsi
The electrification of the transportation sector may have socio-economic benefits such as reducing greenhouse gases, lowering the soaring gas prices, and ending the reliance on imported oil. The integration of plug-in electric vehicles into the electric distribution system may pose potential power quality problems due to the uncertainties in the number of these vehicles, their charging time and locations. Several power quality phenomena such as voltage deviations, voltage imbalance, transformer overload and unbalance are investigated in this thesis. Since the problem is of a stochastic nature, a probabilistic approach using Monte Carlo simulation is adopted in this work to assess potential impact on power quality in the distribution system and hence addressing the uncertainties associated with integrating those electric vehicles. The analysis presented in this work also considers different vehicle types (i.e., plug-in hybrid and battery electric vehicles) for automobiles and pick-up trucks, vehicle penetration and vehicle charging levels. The results of Monte Carlo simulation reveal that Plug-in Battery Electric Vehicles and level 2 charging contribute most impact on undervoltage and transformer overloading, whereas level 1 charging contributes most impact to load unbalance on transformers. Recommendations are made to mitigate such impacts for future work.