Control of Variable Speed Wind Turbines in Islanded Mode of Operation
ABSTRACT Nowadays, technology evolution and deregulation of the electric utility industry enable distributed generation (DG) to play an increasing role in locally satisfying the expanding power demand. In this paper, the islanded operation of an electrical grid supplied by wind turbines, which belong to the most rapidly expanding DG technologies, is studied. Control strategies for power electronics interface of variable speed wind turbines, ensuring fast control of frequency and voltage, are proposed.
Conference Proceeding: An optimal control of marine propulsion system considering ship dynamics[show abstract] [hide abstract]
ABSTRACT: This study investigates the optimal control of a marine propulsion system consisting of an engine, a propeller and ship's parts. First, each part of the system is analytically examined and the system is mathematically modeled. Next, the performance criterion to characterize the system performance is defined and the procedure of optimal trajectory formation is developed. Then, a new control scheme is proposed in which the optimal trajectories are applied for actual control systems. Finally, advantages of the proposed control scheme are discussed according to the simulation results.Control Applications, 2002. Proceedings of the 2002 International Conference on; 02/2002
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ABSTRACT: This paper analyses the repercussions from the connection of wind parks (WP) on the operation of weak electric distribution systems, based on simulation results. The effects on the voltage profile caused by variable-speed (VS) wind turbines (WT) are compared to the effects caused by fixed speed (FS) WTs. Both types of WT are assumed to be equipped with asynchronous machines. In the VS mode of operation, a voltage source converter cascade is used employing field-oriented control for the generator-side converter and three independent hysteresis controllers for the grid-side converter. The distribution system studied is an actual feeder located in a rural area at the southeastern part of mainland Greece. For the simulation of the WP and the grid, a library of WTs and electrical grid components was developed. Using the developed simulation tool, two cases concerning high and low wind speed are studied. General conclusions are drawn concerning the voltage fluctuations, harmonic content, and the penetration of harmonics through the network The advantages of the studied VS operation scheme are confirmed, and the possible increase in the installed capacity of the WP over the FS mode, maintaining the same power quality standards, is estimated.IEEE Power Engineering Review 10/2002; 22(9):55-55.
Conference Proceeding: Control strategies for microgrids emergency operation[show abstract] [hide abstract]
ABSTRACT: Under normal operating conditions, a microgrid (MG) is interconnected with the medium voltage (MV) network. However, planned or unplanned events like maintenance or faults in the MV network, respectively, may lead to MG islanding. In order to deal with islanded operation and even black start following a general blackout, an emergency operation mode must be envisaged. Two possible control strategies were investigated and are described in this paper in order to operate a MG under emergency mode. A sequence of actions for a well succeeded black start procedure, involving microgeneration units, has also been identified contributing for an increase in distribution network reliabilityFuture Power Systems, 2005 International Conference on; 12/2005