Energy storage systems for wave energy converters and microgrids

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dc.check.embargoformatNot applicableen
dc.check.infoNo embargo requireden
dc.check.opt-outNot applicableen
dc.check.reasonNo embargo requireden
dc.check.typeNo Embargo Required
dc.contributor.advisorEgan, Michael G.en
dc.contributor.advisorHayes, John G.en
dc.contributor.authorMurray, Dónal B.
dc.contributor.funderIrish Research Council for Science, Engineering and Technologyen
dc.date.accessioned2013-05-27T10:53:22Z
dc.date.available2013-05-27T10:53:22Z
dc.date.issued2013
dc.date.submitted2013
dc.description.abstractThe thesis initially gives an overview of the wave industry and the current state of some of the leading technologies as well as the energy storage systems that are inherently part of the power take-off mechanism. The benefits of electrical energy storage systems for wave energy converters are then outlined as well as the key parameters required from them. The options for storage systems are investigated and the reasons for examining supercapacitors and lithium-ion batteries in more detail are shown. The thesis then focusses on a particular type of offshore wave energy converter in its analysis, the backward bent duct buoy employing a Wells turbine. Variable speed strategies from the research literature which make use of the energy stored in the turbine inertia are examined for this system, and based on this analysis an appropriate scheme is selected. A supercapacitor power smoothing approach is presented in conjunction with the variable speed strategy. As long component lifetime is a requirement for offshore wave energy converters, a computer-controlled test rig has been built to validate supercapacitor lifetimes to manufacturer’s specifications. The test rig is also utilised to determine the effect of temperature on supercapacitors, and determine application lifetime. Cycle testing is carried out on individual supercapacitors at room temperature, and also at rated temperature utilising a thermal chamber and equipment programmed through the general purpose interface bus by Matlab. Application testing is carried out using time-compressed scaled-power profiles from the model to allow a comparison of lifetime degradation. Further applications of supercapacitors in offshore wave energy converters are then explored. These include start-up of the non-self-starting Wells turbine, and low-voltage ride-through examined to the limits specified in the Irish grid code for wind turbines. These applications are investigated with a more complete model of the system that includes a detailed back-to-back converter coupling a permanent magnet synchronous generator to the grid. Supercapacitors have been utilised in combination with battery systems for many applications to aid with peak power requirements and have been shown to improve the performance of these energy storage systems. The design, implementation, and construction of coupling a 5 kW h lithium-ion battery to a microgrid are described. The high voltage battery employed a continuous power rating of 10 kW and was designed for the future EV market with a controller area network interface. This build gives a general insight to some of the engineering, planning, safety, and cost requirements of implementing a high power energy storage system near or on an offshore device for interface to a microgrid or grid.en
dc.description.abstractIrish Research Council for Science Engineering and Technology (Embark)en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Version
dc.format.mimetypeapplication/pdfen
dc.identifier.citationMurray, D.B. 2013. Energy storage systems for wave energy converters and microgrids. PhD Thesis, University College Cork.en
dc.identifier.endpage233
dc.identifier.urihttps://hdl.handle.net/10468/1137
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2013. Dónal Brendan Murrayen
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/3.0/en
dc.subjectSupercapacitor testingen
dc.subjectWave energy converter, speed controlen
dc.subjectMicrogriden
dc.subjectEnergy storageen
dc.subjectLithium ion batteryen
dc.subject.lcshCapacitorsen
dc.subject.lcshLithium cellsen
dc.subject.lcshRenewable energy sourcesen
dc.thesis.opt-outfalse*
dc.titleEnergy storage systems for wave energy converters and microgridsen
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePHD (Engineering)en
ucc.workflow.supervisorjohn.hayes@ucc.ie*
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