Technical criteria for wind farm power stations connected to the transmission system - Wind Power Integration: Connection and System Operational Aspects - page 284

CC.S2.8 Neutral Earthing

CC.S2.8.1

The winding configuration and method of Earthing of WFPSs
and associated Generator Transformers shall be agreed with the
TSO or, if agreement cannot be reached, determined by the TSO .
The principles applying are as set out in CC 6.8.

CC.S2.9 Automatic Shedding Devices

CC.S2.9.1

Load Shedding external to the WFPS
There is an expectation that WFPSs will continue to operate
outside statutory Frequency limits. The WFPS could be Con-
nected within an Automatic Load Shedding zone as detailed in
OC 4. Consequently, Users shall ensure that Protection on
WFPSs shall have settings to co-ordinate with the settings on the
Automatic Load Shedding equipment as detailed by the TSO on
request by the User .

CC.S2.9.2 Frequency Tolerance and Frequency Shedding of the WFPS

(a) Each WFPS shall be capable of satisfactory operation at any

Frequency within the range of 47.0-51.5 Hz for the mini-
mum time periods specified below unless the TSO has
agreed to the use of any Frequency level relays which will
trip the WFPS within this Frequency range.
Minimum time periods:

Below Nominal
Frequency (Hz)

Above Nominal
Frequency (Hz)

Operation
Requirement

49.5-50.0 50.0-50.5 Continuous

48.4-49.5 50.5-51.5 For a period of 60 minutes

47.5-48.4 - For a period of 30 seconds

(b) Where WFPSs are equipped with rate-of-change-of-frequency

relays or other devices which measure and operate in rela-
tion to a rate-of-change-of-frequency (e.g. a governor) the
procedure in CC .S2.9.2(c) below will be followed to ensure
satisfactory operation of the WFPSs .

(c) The procedure:

(i) At a reasonable time prior to a WFPS being

Connected to the Transmission System , and prior
to any relevant modification to a WFPS or any
relevant Power Station Equipment ,the Generator
shall contact the TSO with details of the proposed