Commission Regulation (EU) 2017/2196Show full title

Article 15 U.K. Automatic under-frequency control scheme

1. The scheme for the automatic control of under-frequency of the system defence plan shall include a scheme for the automatic low frequency demand disconnection and the settings of the limited frequency sensitive mode-underfrequency in the TSO load frequency control (LFC) area.

2. In the design of its system defence plan, each TSO shall provide for the activation of the limited frequency sensitive mode-underfrequency prior to the activation of the scheme for the automatic low frequency demand disconnection, where the rate of change of frequency allows it.

3. Prior to the activation of the automatic low frequency demand disconnection scheme, each TSO and DSO identified pursuant to Article 11(4) shall foresee that energy storage units acting as load connected to its system:

(a) automatically switch to generation mode within the time limit and 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 within the time limit established by the TSO in the system defence plan, automatically disconnect the energy storage unit acting as load.

4. Each TSO shall establish in its system defence plan the frequency thresholds at which the automatic switching or disconnection of energy storage units shall occur. These frequency thresholds shall be lower or equal to the system frequency limit defined for the emergency state in Article 18(3) of Regulation (EU) 2017/1485 and higher than the frequency limit for demand disconnection starting mandatory level laid down in the Annex.

5. Each TSO shall design the scheme for the automatic low frequency demand disconnection in accordance with the parameters for shedding load in real-time laid down in the Annex. The scheme shall include the disconnection of demand at different frequencies, from a ‘starting mandatory level’ to a ‘final mandatory level’, within an implementation range whilst respecting a minimum number and maximum size of steps. The implementation range shall define the maximum admissible deviation of netted demand to be disconnected from the target netted demand to be disconnected at a given frequency, calculated through a linear interpolation between starting and final mandatory levels. The implementation range shall not allow the disconnection of less netted demand than the amount of netted demand to be disconnected at the starting mandatory level. A step cannot be considered as such if no netted demand is disconnected when this step is reached.

6. Each TSO or DSO shall install the relays necessary for low frequency demand disconnection taking into account at least load behaviour and dispersed generation.

7. When implementing the scheme for the automatic low frequency demand disconnection pursuant to the notification under Article 12(2), each TSO or DSO shall:

(a) avoid setting an intentional time delay in addition to the operating time of the relays and circuit breakers;

(b) minimise the disconnection of power generating modules, especially those providing inertia; and

(c) limit the risk that the scheme leads to power flow deviations and voltage deviations outside operational security limits.

If a DSO cannot fulfil the requirements under points (b) and (c), it shall notify the TSO and propose which requirement shall apply. The TSO, in consultation with the DSO shall establish the applicable requirements based on a joint cost-benefit analysis.

8. The scheme for the automatic low frequency demand disconnection of the system defence plan may provide for netted demand disconnection based on frequency gradient provided that:

(a) it is activated only:

(i)

when the frequency deviation is higher than the maximum steady state frequency deviation and the frequency gradient is higher than the one produced by the reference incident;

(ii)

until the frequency reaches the frequency of the demand disconnection starting mandatory level;

(b) it complies with the Annex; and

(c) it is necessary and justified in order to maintain efficiently the operational security.

9. In case the scheme for the automatic low frequency demand disconnection of the system defence plan includes netted demand disconnection based on frequency gradient, as described in paragraph 8, the TSO shall submit, within 30 days of the implementation, a report containing a detailed explanation of the rationale, implementation and impact of this measure to the F1 ... regulatory authority.

10. A TSO may include in the scheme for automatic low frequency demand disconnection of its system defence plan additional steps for netted demand disconnection below the final mandatory level of demand disconnection set out in the Annex.

11. Each TSO shall be entitled to implement additional system protection schemes that are triggered by a frequency smaller or equal to the frequency of the final mandatory level of demand disconnection and which aim at a faster restoration process. The TSO shall ensure that such additional schemes do not further deteriorate frequency.

Textual Amendments

F1 Word in Art. 15(9) omitted (E.W.S.) (31.12.2020) by virtue of The Electricity Network Codes and Guidelines (System Operation and Connection) (Amendment etc.) (EU Exit) Regulations 2019 (S.I. 2019/533), reg. 1(2), Sch. 2 para. 14 (as amended by S.I. 2020/1016, regs. 1(2), 6(2)); 2020 c. 1, Sch. 5 para. 1(1)