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

[摘要] ENGLISH ABSTRACT: In this study the recently proposed slip-synchronous permanent magnet generator (SS-PMG), isconsidered as an alternative to other wind generator topologies. The SS-PMG is connected directlyto the grid without the need for a power electronic converter and it can also be connected directlyto the turbine without a gearbox. Due to the SS-PMG requiring no gearbox or power electronicconverter it is evident that this type of generator have a significant advantage regarding reducedmaintenance and operation costs. The SS-PMG consist of two integrated permanent magnet generatingunits, a directly turbine connected slip permanent magnet generator (slip-PMG) and a directlygrid connected permanent magnet synchronous generator (PMSG). In this, study many of the implementationaspects of the SS-PMG are addressed. It is found that the short-circuit torque andcurrent profiles of both the slip-PMG and PMSG are significantly influenced by the end-windinginductance and PM end-effects. A new analytical method is proposed for the calculation of theend-winding inductance in this study and a new approach is devised to take the PM end-effectsinto account. A very important aspect considered in this thesis, is the stability of the SS-PMGconnected directly to the grid regarding turbine, generator and grid voltage disturbances, whichinfluences the design of the PMSG and slip-PMG units. Furthermore, it is important that the finalSS-PMG design comply to the relevant grid code specifications. For both the PMSG and slip-PMGan 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 SSPMGare verified by means of practical tests in the laboratory and for the SS-PMG interfaced withan existing 15 kW wind turbine system in the field.

[发布机构] Stellenbosch University