Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Electrical Engineering and Computer Science


Prasanta Ghosh


Distributed Generator, Electric Vehicle, Frequency Regulation, Islanding, Non Detection Zone, Reactive Power Service

Subject Categories



Electric power systems (EPSs) are rapidly becoming more complex. Penetration of distributed generators (DGs) are increasing rapidly. Among them, DG units with intermittent renewables resources, such as solar or wind, are attracting more attention. Moreover, plug in electric vehicles (EVs) are expected to be deployed in large numbers over the next decade. These changes present opportunities as well as challenges for reliable and efficient operation of EPS.

Integrating EVs in large scale, would result in over-loading of EPS. Interconnection of DGs could impact adversely on the system operation including power quality and safety of the EPS. However, due to the growing number of EVs in the system, faster charging, shorter battery reaction time, and vehicle-to-grid services, EVs could be attractive sources for system operators (SOs) to improve system reliability while creating opportunity for EV owners to gain monetary benefits. In addition, the potential benefits of DG could be sustained in avoiding or shifting investment in transmission lines and/or transformers, minimizing ohmic losses, and protecting the environment.

In this dissertation, potential benefits and challenges of EVs and DGs are explored. For some potential benefits, the dissertation develops systematic frameworks, in order to facilitate integration of EVs and DGs into the EPS. Also for some challenges, the dissertation presents solutions to analyze and overcome related difficulties.

To study consequences of integrating EVs, a comprehensive model of EV operation is presented. The model covers different modes of operation and includes impact of battery degradation during the operation. The model is then extended to control a large group of EVs efficiently. Several possible ancillary services which could be offered by EVs, including voltage and frequency regulation services, are discussed. Several systematic frameworks are developed to engage EVs in provision of ancillary services, from economical and technical view points. Simulation results clearly indicate EVs ability to participate in ancillary services and possible revenue stream for EV owners.

In terms of DGs, the dissertation addresses a common issue in most of utility companies and that is the risk of unintentional islanding of interconnected DGs. A systematic procedure is presented in this dissertation which can detect any possible operating conditions leading to an unintentional islanding of DGs. The developed procedure can serve utility companies as an analytical tool for any interconnection study, in a timely and costly efficient manner. The procedure is not dependent on the anti-islanding schemes nor DG technologies. Simulation results of different real case studies prove the generality and practicality of the procedure.


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