Technical criteria for wind farm power stations connected to the transmission system - Wind Power Integration: Connection and System Operational Aspects - page 282

CC.S2.6 Co-Ordination with Existing Protection

CC.S2.6.1

A Generator must meet, in relation to a WFPS , the target
clearance times for fault current interchange with the Transmis-
sion System in order to reduce to a minimum the impact on the
Transmission System of faults on circuits owned by Generators .
The target clearance times are measured from fault current
inception to arc extinction and will be specified by the TSO to
meet the requirements of the relevant part of the WFPS pursuant
to CC .S2.1. Unless otherwise agreed, the fault clearance times
specified in the Connection Agreement or other agreement shall
not be greater than:-

(i) 80 ms at 400 kV;

(ii) 100 ms at 275 kV;

(iii) 100 ms at 132 kV; and

(iv) 100 ms at 33 kV

The TSO shall ensure that (subject to any necessary dis-
crimination) the same target fault clearance times can be achieved
by its own Plant and Apparatus at each Connection Point . For
the avoidance of doubt, the Protection here specified is to
achieve fault clearance for faults within (or in the immediate
vicinity of the Wind Farm Station which have not been cleared
by other protection due to a failure of that protection) and such
Protection shall remain insensitive to faults external to the Wind
Farm Power Station in circumstances where the fault contribu-
tion of the Wind Farm Power Station is within the time based
rating of the Wind Farm Power Station Equipment . No form of
action taken by control or Protection Equipment within the
Wind Farm Power Station shall act so as to prevent the Wind
Farm Power Station achieving the Fault Ride Through require-
ment stipulated in CC .S2.3.6

CC.S2.6.2

Unless otherwise agreed in the Connection Agreement or other
agreement, nothing in this CC .S2.6.2 shall prevent a WFPS or the
utility Plant and Apparatus at the Connection Point from hav-
ing faster clearance times than those specified in the Connection
Agreement or other agreement (subject to necessary discrimina-
tion being maintained). The times specified in the Connection
Agreement or other agreement will reflect the TSO's view of the
requirements of both the Transmission System and the User's
System for the expected life time of the Protection (e.g.
15 years). The probability that the fault clearance times stated