Optimal topology and critical evaluation of slip synchronous permanent magnet wind generator

• Main Author: Potgieter, Johannes Hendrik Jacob
• Other Authors: Kamper, M. J.
• Format: Others
• Language: en_ZA
• Published: Stellenbosch : Stellenbosch University 2014
• Subjects: Electrical Wind Generator; Direct Grid Connection; Wind power; Wind turbines; Dissertations > Electrical and electronic engineering; Permanent magnets; UCTD; Theses > Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10019.1/86430

Thesis (PhD)--Stellenbosch University, 2014. === ENGLISH ABSTRACT: In this study the recently proposed slip-synchronous permanent magnet generator (SS-PMG), is considered as an alternative to other wind generator topologies. The SS-PMG is connected directly to the grid without the need for a power electronic converter and it can also be connected directly to the turbine without a gearbox. Due to the SS-PMG requiring no gearbox or power electronic converter it is evident that this type of generator have a significant advantage regarding reduced maintenance and operation costs. The SS-PMG consist of two integrated permanent magnet generating units, a directly turbine connected slip permanent magnet generator (slip-PMG) and a directly grid connected permanent magnet synchronous generator (PMSG). In this, study many of the implementation aspects of the SS-PMG are addressed. It is found that the short-circuit torque and current profiles of both the slip-PMG and PMSG are significantly influenced by the end-winding inductance and PM end-effects. A new analytical method is proposed for the calculation of the end-winding inductance in this study and a new approach is devised to take the PM end-effects into account. A very important aspect considered in this thesis, is the stability of the SS-PMG connected directly to the grid regarding turbine, generator and grid voltage disturbances, which influences the design of the PMSG and slip-PMG units. Furthermore, it is important that the final SS-PMG design comply to the relevant grid code specifications. For both the PMSG and slip-PMG an extensive design optimisation is done, with several novel wind generator concepts introduced. In this study the dynamic behaviour, grid connection aspects and operational principles of the SSPMG are verified by means of practical tests in the laboratory and for the SS-PMG interfaced with an existing 15 kW wind turbine system in the field. === AFRIKAANSE OPSOMMING: In hierdie studie word die onlangs voorgestelde, glip-sinchroon permanent magneet generator (GSPMG), oorweeg as ’n alternatief vir ander wind generator topologieë. Die GS-PMG word direk aan die netwerk gekonnekteer sonder die nodigheid van ’n drywingselektroniese omsetter en dit kan ook direk aan die turbine gekoppel word sonder ’n ratkas. Omdat die GS-PMG geen ratkas of drywingselektroniese omsetter benodig nie, is dit duidelik dat hierdie tipe generator ’n geweldige voordeel het rakende verminderde onderhoud en operasionele kostes. Die GS-PMG bestaan uit twee geïntegreerde permanent magneet generator eenhede, ’n direkte turbine gekoppelde glip permanent magneet generator (glip-PMG) en ’n direkte netwerk gekonnekteerde permanent magneet sinchroon generator (PMSG). In hierdie studie word baie van die implementerings aspekte van die SS-PMG aangeraak. Daar word gevind dat die kortsluit draaimoment en stroom profiele van beide die glip- PMG en PMSG geweldig deur die end-wikkeling induktansie en PM randeffekte beïnvloed word. Dus, word ’n nuwe analitiese metode voorgestel vir die uitwerk van die end-wikkeling induktansie in hierdie studie en ’n nuwe benadering word voorgestel om die PM randeffekte in ag te neem. ’n Baie belangrike aspek om te oorweeg in hierdie tesis, is die stabiliteit van die GS-PMG direk aan die netwerk gekoppel rakende turbine, generator en netwerkspanning steurnisse, wat die ontwerp van die PMSG en glip-PMG eenhede beïnvloed. Dit is ook belangrik dat die finale SS-PMG ontwerp voldoen aan die relevante netwerkkode spesifikasies. Vir beide die PMSG en glip-PMG word ’n deeglike ontwerpsoptimering gedoen, met talle nuwe wind generator konsepte voorgestel. In hierdie studie word die dinamiese gedrag, netwerk konneksie aspekte en operasionele kenmerke van die GSPMG geverifieer met behulp van praktiese toetse in die laboratorium en vir die SS-PMG geïntegreer met ’n bestaande 15 kW wind turbine stelsel in die veld.