Photovoltaic (PV) DGs can be optimized to provide reactive power support to the grid,
although this feature is currently rarely utilized as most DG systems are designed to
operate with unity power factor and supply real power only to the grid. In this work, the
voltage stability of a power system embedded with PV DG is examined in the context of
the high reactive power requirement after a voltage sag or fault. A real-time dynamic
multi-function power controller that enables renewable source PV DGs to provide the
reactive power support necessary to maintain the voltage stability of the microgrid, and
consequently, the wider power system is proposed.
The loadability limit necessary to maintain the voltage stability of an interconnected
microgrid is determined by using bifurcation analysis to test for the singularity of the
network Jacobian and load differential equations with and without the contribution of
the DG. The maximum and minimum real and reactive power support permissible from
the DG is obtained from the loadability limit and used as the limiting factors in
controlling the real and reactive power contribution from the PV source. The designed
controller regulates the voltage output based on instantaneous power theory at the
point-of-common coupling (PCC) while the reactive power supply is controlled by means
of the power factor and reactive current droop method. The control method is
implemented in a modified IEEE 13-bus test feeder system using PSCAD® power system
analysis software and is applied to the model of a Tampa Electric® PV installation at
Lowry Park Zoo in Tampa, FL.
This dissertation accomplishes the systematic analysis of the voltage impact of a PV DGembedded
power distribution system. The method employed in this work bases the
contribution of the PV resource on the voltage stability margins of the microgrid rather
than the commonly used loss-of-load probability (LOLP) and effective load-carrying
capability (ELCC) measures. The results of the proposed method show good
improvement in the before-, during-, and post-start voltage levels at the motor
terminals. The voltage stability margin approach provides the utility a more useful
measure in sizing and locating PV resources to support the overall power system
stability in an emerging smart grid.
| Identifer | oai:union.ndltd.org:USF/oai:scholarcommons.usf.edu:etd-4834 |
| Date | 10 November 2010 |
| Creators | Omole, Adedamola |
| Publisher | Scholar Commons |
| Source Sets | University of South Flordia |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Graduate Theses and Dissertations |
| Rights | default |
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