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Analysis and Improvement of Dynamic Performance and Fault Ride-Through Capability of Wind Turbines Based on Doubly-Fed Induction Generators
, Ph.D. Dissertation Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
Variable speed wind turbines (VSWTs) provide the capability of wide speed operation and independent control of active and reactive power. In contrast to the fixed speed WTs, they have higher efficiency, power quality and controllability. VSWTs are mainly divided in two categories: WTs based on doubly fed induction generator (DFIG) and WTs based on full converter with permanent magnet synchronous generator.
At now, among the different alternatives to obtain VSWTs, DFIGs are the most commonly used. This is because the voltage source converter (VSC) in DFIG has to handle a fraction of the total power under steady state conditions, and thus the size and cost of the converter is reduced....
At now, among the different alternatives to obtain VSWTs, DFIGs are the most commonly used. This is because the voltage source converter (VSC) in DFIG has to handle a fraction of the total power under steady state conditions, and thus the size and cost of the converter is reduced....
Analysis and Solution Proposal for Improving the Resiliency of High Voltage Cathode Power Supply
, M.Sc. Thesis Sharif University of Technology ; Kaboli, Shahriyar (Supervisor) ; Safdarian, Amir (Co-Supervisor)
Abstract
High voltage power supplies (HVPS) are widely used to supply the vacuum tubes. The function of this power supply is disturbed by some internal and external faults. One of the external faults is the arc fault in the tube. The amount of delivered energy from the HVPS to the tube is an important issue during the arc fault in the tube. The conventional protection mechanism consists of a shunt crowbar device which divert the fault current from the tube arc. The crowbar circuit is usually built with thyristor in most cases. This type of crowbar cannot be turned off simply by protection command. It is a drawback since if the fault is transient such as arc in the load or false fault detection is...
Analysis and Enhancement of Low Voltage Ride Through Of Wind Turbines with Brushless Doubly Fed Induction Generator
, Ph.D. Dissertation Sharif University of Technology ; Oraee Mirzamani, Hashem (Supervisor) ; Tohidi, Sajjad (Co-Advisor)
Abstract
Wind energy technologies guarantee low pollution and operational costs. Using a DFIG and a fractionally rated power electronics converter gives variable speed operation with a low cost drive train. As energy policy organizations have allocated a considerable quota of wind energy generation to offshore wind farms, the absence of slip rings and brushes in the brushless DFIG (BDFIG) is an advantage for offshore wind turbines where maintenance is vital and expensive. With increasing wind power penetration in power systems, grid code requirements are an important consideration for the ride-through capability of wind farms through voltage dips, particularly for multi- MW wind turbine generators....