The effect of shaft modelling on the assessment of fault CCT and the power quality of a wind farm

The global trend of electricity market deregulation has led to an increasing number of wind farms integrated into utilities´s network at distribution level. It has been reported that the incorporation of wind farms into distribution networks gives rise to severe voltage recovery problem with regard to wind power based embedded generator (WBPEG) following a fault condition on the associated network This paper presents the result of an investigation aiming at determining the effect of including the windmill shaft on voltage recovery following a fault on the network. It is conducted on a simulated system using EMTP program. This work has shown that the critical clearing time (CCT) that defines the stability limit of WBPEG can be much lower when the windmill shaft is included. It has also shown that embedded generator (EG) subjected to a network fault can have an aggravated effect on distribution network power quality, which has not previously been identified when a windmill lump model is used In order to improve voltage recovery at the terminals of a windmill and consequently its stability margin, reactive power injection technique using static shunt capacitor (SSC) has been proposed