CHAPTER IISYSTEM DEFENCE PLAN
SECTION 2 Measures of the System Defence Plan
Article 18Frequency deviation management procedure
1.
The procedure for the management of frequency deviations of the system defence plan shall contain a set of measures to manage a frequency deviation outside the frequency limits defined for the alert state in Article 18(2) of Regulation (EU) 2017/1485. The frequency deviation management procedure shall be in line with the procedures set out for remedial actions which need to be managed in a coordinated way F1... and shall fulfil at least the following requirements:
(a)
a decrease of generation shall be smaller than the decrease of load during under-frequency events; and
(b)
a decrease of generation shall be greater than the decrease of load during over-frequency events.
2.
Each TSO shall adapt the operating mode of its LFC in order to prevent interference with manual activation or deactivation of active power as laid down in paragraphs 3 and 5.
3.
Each TSO shall be entitled to establish an active power set-point that each SGU identified pursuant to point (c) of Article 11(4) shall maintain, provided that the set-point fulfils the technical constraints of the SGU. Each TSO shall be entitled to establish an active power set-point that each defence service provider shall maintain provided this measure applies to them pursuant to the terms and conditions referred to in Article 4(4) and the set-point respects the technical constraints of the defence service provider. The SGUs and defence service providers shall execute without undue delay the instructions given by the TSO directly or indirectly through DSOs and shall remain in that state until further instructions are issued. Where the instructions are given directly, the TSO shall inform the relevant DSOs without undue delay.
4.
Each TSO shall be entitled to disconnect SGUs and defence service providers, directly or indirectly through DSOs. SGUs and defence service providers shall remain disconnected until further instructions are issued. Where SGUs are directly disconnected, the TSO shall inform the relevant DSOs without undue delay. Within 30 days of the incident, the TSO shall prepare a report containing a detailed explanation of the rationale, implementation and impact of this action and submit it to the F2regulatory authority as well as make it available to the significantly affected system users.
5.
Prior to the activation of the automatic low frequency demand disconnection scheme set out in Article 15 and provided that the rate of change of frequency allows it, each TSO shall, directly or indirectly through DSOs, activate demand response from the relevant defence service providers and:
(a)
switch energy storage units acting as load to generation mode at an active power set-point established by the TSO in the system defence plan; or
(b)
when the energy storage unit is not capable of switching fast enough to stabilise frequency, manually disconnect the energy storage unit.