The design and regulation of power equipments which installed in distribution system are based on single direction power flow. When distributed generators (DG) are added into distribution system, it may cause some technical problems such as two-way current, fault capacity and power quality. In general, the utility should make sure that its power system could be operated safely and reliably before integrating DG into the system. If there are no complete measurements for DG, the capacity of DG would be restricted by fault current, short circuit capacity, feeder voltage or other problems. In this research, the focus is on the influence of DG operations in distribution system and the increase of DG integration capacity. The impacts of different combinations of DG generation profiles and control strategies are first analyzed, followed by the use of particle swarm optimization (PSO) technique to search for better feeder reconfigurations in order to increase DG integration capacity.

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains x, 62 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 46-48).

Thesis (M.S.)--Tennessee Technological University, 2009. / Title from title page screen (viewed on Mar. 3, 2010). Bibliography: leaves 84-89.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy

Distributed generation (DG) is increasingly employed in modern utility grids to address the growing complexity and size of consumer energy demands. The obstacles associated with DG integration are related to the additive effect the DG has on the short circuit current characteristics of power systems during short circuit conditions. This thesis proposes a novel mitigation technique for synchronous machine based DG integration effects on existing radial fuse-recloser protection infrastructure. The mitigation method provides a comparative analysis of the utilization of resistive (R), inductive (L) and resonant (LC) type superconducting fault current limiters (FCLs) for prevention of excessive fault current contribution from DG sources. Within the frame of reference of this thesis is an interrogation into the effects of synchronous machine based DG sources, in conjunction with mitigation capabilities of FCL integration in the context of fuse-recloser coordination, recloser sensitivity and recloser directionality behavior during radial distribution short circuit conditions. For validation purposes, the proposed methods are demonstrated on a suburban test benchmark using the PSCAD/EMTDC program.

Solar power is considered a very promising source for electric power generation. The abundance of sunlight over a large area of the earth surface gives rise to several applications of photovoltaic systems. Electricity can be generated from sunlight either directly by employing the photovoltaic effect, or by using energy from the sun to heat up a working fluid that can be used to power up electricity generators. These two technologies are widely used today to provide power to either stand-alone loads or for connection to the power system grid. Maximum power point tracking (MPPT) is a very important consideration that is taken into account when building a new photovoltaic power system. This is needed in order to extract maximum power output from a PV array under varying atmospheric conditions to maximize the return on initial investments. Several techniques have been used to tackle this problem including perturb and observe (P&O), incremental conductance (IncCond) and fuzzy logic based algorithms. Judging between these techniques is based on their speed of locating the maximum power point (MPP) of a PV array under given atmospheric conditions, besides the cost and complexity of implementing them. The P&O and IncCond algorithms have a low implementation complexity but their tracking speed is slow. Fuzzy logic techniques are faster but suffer from high implementation complexity. One of the goals of this thesis is to present an MPPT algorithm implementation that is based on the fractional open circuit voltage method. This technique is easy to implement and offers a fast tracking speed for the MPP of a PV array. It provides an approximation within 4-5% of the maximum power point, which is a tradeoff between the speed and accuracy of operation around the MPP. It offers a speed advantage in grid connected PV systems. The P&O algorithm, which is very common, is difficult to implement under these conditions due to its poor response time. There is also a need for developing control techniques for three phase grid connected PV systems including a method for DC link voltage control that can stabilize the voltage at the inverter input. This area of research is currently growing with the increase in number of PV installations backed up by government incentives in several countries. In addition to the previously mentioned points, this work is intended to be used in further research to replace the representation of PV arrays as a simple DC source when included in power system studies. That is a basic assumption and does not take into consideration the various dynamics caused by changing solar irradiation and surface temperature of the array.

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains ix, 141 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 136-141).

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

The research presented in this dissertation primarily focuses on providing analytical frequency-domain equations that use the system and controller parameters to accurately characterize the power conversion harmonics resulting from the deployment of hysteresis current-controlled inverters within the ac network. In addition, the ac and dc harmonic interactions under both ideal system conditions (constant dc excitation and pure sinusoidal ac voltages) and non-ideal system conditions (harmonic terms are added to the dc and ac sources) are derived for the fixed- and variable-band hysteresis current control. The spectral characteristics, such as frequency orders, spectral magnitude and bandwidth, are given in terms of line and control parameters, a development not only useful in analyzing the harmonic output sensitivity to line and controller parameter variations, but also in filter and system design. Various simulation studies compared results obtained from the developed models to those obtained from the Fourier analysis of MATLAB/Simulink output with very good agreement. The developed models proved their reliability and improved numerical efficiency in harmonic studies compared to those performed using time-domain simulations.