Date of Award

2019

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Electrical Engineering (PhD)

Administrative Home Department

Department of Electrical and Computer Engineering

Advisor 1

Bo Chen

Committee Member 1

Sumit Paudyal

Committee Member 2

Seyed A. (Reza) Zekavat

Committee Member 3

Ye Sun

Abstract

The goal of this research is to study the control approaches of the electric vehicle – grid integration systems in a power distribution grid to benefit the electric vehicle charging customers and the grid operation. To find the balance of both aspects, a series of modeling and simulation have been conducted to validate the effectiveness of the developed control approaches. The impact of the plug-in electric vehicle (PEV) charging activity on the distribution power grid is analyzed. The PEV charging behavior model is established through the statistical analysis of the National Highway Travel Survey. This charging behavior model is used to generate the PEV charging load profiles for the investigation of the PEV charging impacts on the local distribution transformer aging and the network voltage deviation. The simulation results indicate that the high penetration rate of PEV charging potentially leads to serious distribution transformer aging and voltage problems to the end users in the remote side of a distribution line. To mitigate the PEV charging impacts, scheduling methods are investigated based on the existing utility programs, such as the Time of Use and Direct Load Control, and optimization techniques. The charging scheduling shifts the PEV charging load to the grid off-peak period to flatten the load profile. Therefore, it mitigates the PEV charging resulted overloading, transformer aging, and voltage deviation problems. To improve the customer acceptance of PEV charging control, the PEV charging in a distribution grid form a competition game, which allows individual PEV charging xiii customers to pursue charging cost minimization while various grid and customer constraints are met. Due to that the individual objectives and constraints are related to the PEVs charging strategy selection, the charging game is considered as a generalized Nash Equilibrium problem (GNEP). The Nikaido-Isoda reformulation function is used to solve the GNEP. The obtained PEV charging strategies lead to the lowest PEV charging cost and guarantee the grid operation safety and customer requirement. The obtained solution strategies of this problem are regarded as the Nash Equilibriums of the game. To explore the possibility of providing grid services by using the PEV smart charging method, a study of distribution grid level vehicle - grid integration control with voltage regulation is conducted. In this study, the PEV charging control is designed at both Microgrid-level and distribution-level. The Microgrid controllers aim to optimally allocate the limited power to the charging PEVs. When a distribution grid voltage violation occurs, a distributed multi-Microgrids negotiation is triggered to find the best power curtailment values for individual Microgrids, which satisfy the voltage recovery requirement and have a minimal impact on the grid operation. The last part of the dissertation presents the effort of developing a real-time VGI simulation platform at distribution grid level in a real-time power system simulator, OPAL-RT. The efforts include the algorithm implementation to eliminate time overrun and the cloud communication for information exchange between a real-world VGI Microgrid and the real-time simulation model in OPAL-RT.

Available for download on Wednesday, August 12, 2020

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