Doctoral Dissertations

Keywords and Phrases

Dc-ac Inverter; Energy Storage Integration; Ultracapacitors


"Grid integration of distributed energy resources (DERs) is increasing rapidly. Integration of various types of energy storage technologies like batteries, ultracapacitors (UCAPs), superconducting magnets and flywheels to support intermittent DERs, such as solar and wind, in order to improve their reliability is becoming necessary. Of all the energy storage technologies UCAPs have low energy density, high power density and fast charge/discharge characteristics. They also have more charge/discharge cycles and higher terminal voltage per module when compared to batteries. All these characteristics make UCAPs ideal choice for providing support to events on the distribution grid which require high power for short spans of time. UCAPs have traditionally been limited to regenerative braking and wind power smoothing applications.

The major contribution of this dissertation is in integrating UCAPs for a broader range of applications like active/reactive power support, renewable intermittency smoothing, voltage sag/swell compensation and power quality conditioning to the distribution grid. Renewable intermittency smoothing is an application which requires bi-directional transfer of power from the grid to the UCAPs and vice-versa by charging and discharging the UCAPs. This application requires high active power support in the 10s-3min time scale which can be achieved by integrating UCAPs through a shunt active power filter (APF) which can also be used to provide active/reactive power support. Temporary voltage sag/swell compensation is another application which requires high active power support in the 3s-1min time scale which can be provided integrating UCAPs into the grid through series dynamic voltage restorer (DVR). All the above functionalities can also be provided by integrating the UCAPs into a power conditioner topology."--Abstract, page iv.


Crow, Mariesa

Committee Member(s)

Chowdhury, Badrul H.
McMillin, Bruce M.
Ferdowsi, Mehdi
Kimball, Jonathan W.


Electrical and Computer Engineering

Degree Name

Ph. D. in Electrical Engineering


Missouri University of Science and Technology

Publication Date

Spring 2014

Journal article titles appearing in thesis/dissertation

  • An integrated active power filter-ultracapacitor design to provide intemittency smoothing and reactive power support to the distribution grid
  • An integrated dynamic voltage restorer-ultracapacitor design for improving the power quality of the distribution grid
  • An ultracapacitorintegrated power conditioner for reducing intermittencies and improving power quality of distribution grid


xiv, 114 pages

Note about bibliography

Includes bibliographical references.


© 2014 Deepak Somayajula, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Subject Headings

Photovoltaic power systems
DC-to-DC converters
Distributed generation of electric power
Energy storage

Thesis Number

T 10482

Electronic OCLC #