Commission Regulation (EU) 2017/2196Show full title

SECTION 2 U.K. Measures of the System Defence Plan

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)

Article 16 U.K. Automatic over-frequency control scheme

1. The scheme for automatic over-frequency control of the system defence plan shall lead to an automatic decrease of the total active power injected in each LFC area.

2. In consultation with the other TSOs of its synchronous area, each TSO shall set out the following parameters of its scheme for automatic over-frequency control:

(a) the frequency thresholds for its activation; and

(b) the reduction ratio of injection of active power.

3. Each TSO shall design its automatic over-frequency control scheme taking into account the capabilities of the power generating modules concerning the limited frequency sensitive mode — overfrequency and of the energy storage units, in its LFC area. If the limited frequency sensitive mode — overfrequency does not exist or is not sufficient to fulfil the requirements set out in points (a) and (b) of paragraph 2, each TSO shall set up in addition a step-wise linear disconnection of generation in its LFC area. The TSO shall establish the maximum size of the steps for disconnection of power generating modules and/or of HVDC systems in consultation with the other TSOs of its synchronous area.

Article 17 U.K. Automatic scheme against voltage collapse

1. The automatic scheme against voltage collapse of the system defence plan may include one or more of the following schemes, depending on the results of a TSO's assessment of system security:

(a) a scheme for low voltage demand disconnection according to Article 19(2) of Regulation (EU) 2016/1388;

(b) a blocking scheme for on load tap changer according to Article 19(3) of Regulation (EU) 2016/1388; and

(c) system protection schemes for voltage management.

2. Unless the assessment pursuant to paragraph 1 demonstrates that implementing a blocking scheme for on load tap changer is not necessary to prevent a voltage collapse in the TSO control area, the TSO shall establish the conditions under which the on load tap changer shall block according to Article 19(3) of Regulation (EU) 2016/1388, including at least:

(a) the blocking method (local or remote from control room);

(b) the voltage level threshold at the connection point;

(c) the flow direction of reactive power; and

(d) the maximum lapse of time between the detection of the threshold and the blocking.

Article 18 U.K. Frequency 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 F2 ... 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 [F3 regulatory 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.

Textual Amendments

F2 Words in Art. 18(1) 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. 15(2) (as amended by S.I. 2020/1016, regs. 1(2), 6(2)); 2020 c. 1, Sch. 5 para. 1(1)

F3 Words in Art. 18(4) substituted (E.W.S.) (31.12.2020) by 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. 15(3) (as amended by S.I. 2020/1016, regs. 1(2), 6(2)); 2020 c. 1, Sch. 5 para. 1(1)

Article 19 U.K. Voltage deviation management procedure

1. The procedure for the management of voltage deviations of the system defence plan shall contain a set of measures to manage voltage deviations outside the operational security limits set out in Article 25 of Regulation (EU) 2017/1485.

2. Each TSO shall be entitled to establish a reactive power range or voltage range and instruct the DSOs and SGUs identified for this measure pursuant to Article 11(4) to maintain it, in accordance with Articles 28 and 29 of Regulation (EU) 2017/1485.

3. Upon request of neighbouring TSO in emergency state, each TSO shall make available all reactive power capabilities that do not lead its transmission system into emergency state or blackout state.

Article 20 U.K. Power flow management procedure

1. The procedure for power flow management of the system defence plan shall include a set of measures to manage power flow outside the operational security limits set out in Article 25 of Regulation (EU) 2017/1485.

2. Each TSO shall be entitled to establish an active power set-point that each SGU identified pursuant to point (c) Article 11(4) shall maintain provided that the set-point respects 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 providers. 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.

3. 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 SGU 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 [F4 regulatory authority].

Textual Amendments

F4 Words in Art. 20(3) substituted (E.W.S.) (31.12.2020) by 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. 16 (as amended by S.I. 2020/1016, regs. 1(2), 6(2)); 2020 c. 1, Sch. 5 para. 1(1)

Article 21 U.K. Assistance for active power procedure

1. In case of absence of control area adequacy in the day-ahead or intraday timeframe, identified pursuant to paragraphs 1 and 2 of Article 107 of Regulation (EU) 2017/1485, and prior to any potential suspension of market activities pursuant to Article 35, a TSO shall be entitled to request assistance for active power from:

(a) any balancing service provider, which, upon the TSO request, shall change its availability status to make available all its active power, provided it was not already activated through the balancing market, and conforming to its technical constraints;

(b) any SGU connected in its LFC area, which does not already provide a balancing service to the TSO, and which, upon the TSO request, shall make available all its active power, conforming to its technical constraints; and

(c) other TSOs that are in the normal or alert state.

2. A TSO may activate the assistance for active power from a balancing service provider or a SGU, under points (a) and (b) of paragraph 1, only if it has activated all balancing energy bids available, taking into account the available cross zonal capacity at the moment of absence of adequacy of the control area.

3. Each TSO who has been subject to a request for assistance for active power pursuant to paragraph 1(c) shall:

(a) make available its unshared bids;

(b) be entitled to activate the available balancing energy, in order to provide the corresponding power to the requesting TSO; and

(c) be entitled to request the assistance for active power from its balancing service providers and from any SGU connected in its LFC area which does not already provide a balancing service to the TSO, in order to provide the corresponding assistance for active power to the requesting TSO.

4. When activating the active power requested pursuant to paragraph 1(c), the requesting and the requested TSOs shall be entitled to use:

(a) available cross-zonal capacity in case the activation is made before the intraday cross-zonal gate closure time and if the provision of concerned cross-zonal capacities has not been suspended pursuant to Article 35;

(b) additional capacity that may be available due to real-time status of the system in which case the requesting and the requested TSOs shall coordinate with other significantly affected TSOs in accordance with Article 6(5).

5. Once the requested and requesting TSOs have agreed on the conditions for the provision of assistance for active power, the agreed amount of active power and timeslot for the provision shall be firm, unless the transmission system of the TSO providing the assistance enters into the emergency or blackout state.

Article 22 U.K. Manual demand disconnection procedure

1. In addition to the measures set out in Articles 18 to 21, each TSO may establish an amount of netted demand to be manually disconnected, directly by the TSO or indirectly through DSOs, when necessary to prevent the propagation or worsening of an emergency state. Where demand is to be directly disconnected, the TSO shall inform the relevant DSOs without delay.

2. The TSO shall activate the manual disconnection of the netted demand referred to in paragraph 1 to:

(a) resolve overloads or under voltage situations; or

(b) resolve situations in which assistance for active power pursuant to Article 21 has been requested but is not sufficient to maintain adequacy in day-ahead and intraday timeframes in its control area, pursuant to Article 107 of Regulation (EU) 2017/1485, leading to a risk of frequency deterioration in the synchronous area.

3. The TSO shall notify DSOs of the amount of netted demand established pursuant to paragraph 1 to be disconnected on their distribution systems. Each DSO shall disconnect the notified amount of netted demand, without undue delay.

4. 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 [F5 regulatory authority].

Textual Amendments

F5 Words in Art. 22(4) substituted (E.W.S.) (31.12.2020) by 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. 17 (as amended by S.I. 2020/1016, regs. 1(2), 6(2)); 2020 c. 1, Sch. 5 para. 1(1)