As expected, the DFIG contribution is higher, but still within the technical limits, as compared to SCIG due to the inverter interface at the rotor side. With connection of more DFIGs, the THD will also increase unless a higher capacity SC is connected to the network.

Flicker (for the SCIG based system) and Harmonic assessment (for the DFIG based system) can both be used in determining the hosting capacity of the hybrid system.

3.2. Cranking up of other WECS

A study is undertaken to determine the effect of starting other WECSs in the same string as the already operational WECSs. Modelling of the DFIG starting procedure has been discussed in previous research by the same author [34]. SCIG based WECS applies the same torque control scheme. Figs. 13 and 14 shows the results obtained.