Directional ground fault (67Ns) setting in ungrounded system

[thuongvn]

I have a question regarding setting calculation for 64, 67Ns in 6kV ungrounded system.
To protect ground fault of motor 340kW I use function 64, 67Ns of Relay 7SK803 (Siemens) but I don't know how to calculate setting:
1. 64
- L-Gnd voltage of faulted phase Vph min
- L-Gnd voltage of unfaulted phase Vph max
- Ground displacement voltage
2. 67Ns
- Release directional element
- Correction angle for dir. determination
- Measurement method for direction (Cos phi or Sin phi)

I referred experience of Slavag on thread238-252067 but angle setting range of relay is -45<=...<=45 so can't apply his value.

Please show me calculation method.

Thanks.