| 1. |
- Ulvgård, Liselotte, 1988-, et al.
(författare)
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Line Force and Damping at Full and Partial Stator Overlap in a Linear Generator for Wave Power
- 2016
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Ingår i: Journal of Marine Science and Engineering. - : MDPI AG. - 2077-1312. ; 4:4
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Tidskriftsartikel (refereegranskat)abstract
- A full scale linear generator for wave power has been experimentally evaluated bymeasuring the line force and translator position throughout the full translator stroke. The measuredline force, in relation to translator speed, generator damping and stator overlap, has been studied bycomparing the line force and the damping coefficient, γ, for multiple load cases along the translatorstroke length. The study also compares the generator ’s behavior during upward and downwardmotion, studies oscillations and determines the no load losses at two different speeds. The generatordamping factor, γ, was determined for five different load cases during both upward and downwardmotion. The γ value was found to be constant for full stator overlap and to decrease linearly witha decreasing overlap, as the translator moved towards the endstops. The decline varied with theexternal load case, as previously suggested but not shown. In addition, during partial stator overlap,a higher γ value was noted as the translator was leaving the stator, compared to when it was enteringthe stator. Finally, new insights were gained regarding how translator weight and generator dampingwill affect the translator downward motion during offshore operation. This is important for powerproduction and for avoiding damaging forces acting on the wave energy converter during operation.
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| 2. |
- Ulvgård, Liselotte, et al.
(författare)
-
Offshore Measurement System for WavePower : Using Current Loop Feedback
- 2016
-
Ingår i: Electronics. - : MDPI AG. - 2079-9292. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the design and testing of a measurement system for wave powergenerators. The work is part of a project to build a robust and cheap measurement system for offshoremonitoring of wave power farms. Due to the harsh offshore environment, low accessibility andhigh cost for installation and maintenance, it is of key importance to minimize power consumption,complexity and cost of each measurement unit. For the first prototype, the objective was to measurevoltage, current and translator position inside the linear wave power generator. For this, twoprinted circuit boards (PCBs) were developed, using a two wire current loop transmitter setup.They were tested separately and in a three phase setup inside a wave power generator duringonshore tests. To ensure stability, speed and accuracy in the signal transfer, the PCBs were tested forlinearity, frequency response and step response. In addition, power consumption was measured,for operational time evaluation. Results show good agreement between expected and measuredperformance, with an input range of ±1560 V and ±420 A for alternating current measurements anda bandwidth of 10 kHz and 7 kHz, for voltage and current measurements, respectively. The powerconsumption was measured to 0.5 W for each measurement unit, at 24 V feed.
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