VARIABLE-SPEED ALTERNATING-CURRENT MOTORS WITHOUT COMMUTATORS*

2009 ◽  
Vol 35 (2) ◽  
pp. 438-446
Keyword(s):  
Alternating Current ◽  
Variable Speed

scholarly journals Variable-Speed Engines on Wind Farm Support Vessels

2020 ◽  
Vol 8 (3) ◽  
pp. 229 ◽  
Author(s):  
Kristian Eikeland Holmefjord ◽  
Lars Husdal ◽  
Martijn de Jongh ◽  
Sverre Torben
Keyword(s):  
Direct Current ◽  
Diesel Engines ◽  
Wind Farm ◽  
East Coast ◽  
Frequency Converter ◽  
Real Life ◽  
Alternating Current ◽  
Variable Speed ◽  
Fixed Frequency ◽  
Fuel Savings

We examine the fuel savings of Edda Passat, a newly constructed wind farm support vessel that utilizes a common direct current (DC) grid. This enables its diesel engines to operate at variable speeds by using frequency converter technology. A detailed investigation of these benefits has been performed based on real-life measurements from three months of operations in the Race Bank wind farm off the east coast of England. The calculated fuel savings of Edda Passat achieved via its variable-speed engines are 21% lower compared to using a conventional alternating current (AC) grid with a fixed frequency. This paper will explain the technology, measurements, and results in detail.

Adjustment of Hydro-Governor Characteristics Using Separate Drive for the Speed-Sensing Element

1965 ◽  
Vol 87 (1) ◽  
pp. 13-17 ◽  
Author(s):  
L. M. Hovey
Keyword(s):  
Direct Current ◽  
Low Frequency ◽  
Alternating Current ◽  
Variable Speed ◽  
Sensing Element ◽  
Variable Speed Drive ◽  
Precise Control ◽  
Speed Change ◽  
Method Of Adjustment

This paper describes the application of a variable-speed drive for the speed-sensing element of a conventional hydro-governor which makes it possible to measure accurately the deflection of the speeder rod for a given speed change from normal. When this characteristic is determined in the field, changes can be made to the control springs if necessary, to make all machines consistent. The device may also be applied to measure directly both the permanent and temporary speed droops of the governor and allow these quantities to be readjusted to the desired values. The advantage of this method of adjustment is that it permits all the work to be carried out with the main machine shutdown. The variable-speed drive consists of a small motor-generator set which supplies direct-current power to a rotary converter, which in turn delivers low-frequency alternating-current power to the speed-sensing motor on the governor. The rotary converter and the motor-generator set are controlled by a system which gives precise control over the speed which is measured by an accurate tachometer.

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