**5.6 External fault**

When LG fault is applied on the F7 location, which is in the grid and considered an external fault to the wind farm, the ratio of negative sequence voltage to positive sequence voltage and negative sequence current to positive sequence current is less than the set value [14]. So, as per the algorithm, relays R1 to R3 issued delayed tripping at 0.21 s after the fault instant. For all the other external faults, the variation of V1, V2/V1, and I2/I1 are shown in **Table 4**.


**Table 3.**

*Internal fault on feeder 1, 2, and 3 near POC.*

*An Algorithm for Default Detection of Wind Turbine Generators DOI: http://dx.doi.org/10.5772/intechopen.104793*


**Table 4.**

*External fault of W1, W2, and W3 at grid side.*
