CHAPTER IIIU.K. RESTORATION PLAN

SECTION 3 U.K. Frequency management

Article 28U.K.Frequency management procedure

1.The frequency management procedure of the restoration plan shall contain a set of measures aiming at restoring system frequency back to the nominal frequency.

2.Each TSO shall activate its frequency management procedure:

(a)in preparation of the resynchronisation procedure, when a synchronous area is split in several synchronised regions;

(b)in case of frequency deviation in the synchronous area; or

(c)in case of re-energisation.

3.The frequency management procedure shall include at least:

(a)a list of actions regarding the setting of the load-frequency controller before the appointment of frequency leaders;

(b)the appointment of frequency leaders;

(c)the establishment of target frequency in case of bottom-up re-energisation strategy;

(d)frequency management after frequency deviation; and

(e)frequency management after synchronous area split.

(f)the determination of the amount of load and generation to be reconnected, taking into account the available active power reserves within the synchronised region in order to avoid major frequency deviations.

Article 29U.K.Appointment of a frequency leader

1.During system restoration, when a synchronous area is split in several synchronised regions, the TSOs of each synchronised region shall appoint a frequency leader, in accordance with paragraph 3.

2.During system restoration, when a synchronous area is not split but the system frequency exceeds the frequency limits for the alert state as defined in Article 18(2) of Regulation (EU) 2017/1485, all TSOs of the synchronous area shall appoint a frequency leader, in accordance with paragraph 3.

3.The TSO with the highest real-time estimated K-factor shall be appointed as the frequency leader, unless the TSOs of the synchronised region, or of the synchronous area, agree to appoint another TSO as the frequency leader. In that case, the TSOs of the synchronised region, or of the synchronous area, shall consider the following criteria:

(a)the amount of available active power reserves and especially frequency restoration reserves;

(b)the capacities available on interconnectors;

(c)the availability of frequency measurements of TSOs of the synchronised region or of the synchronous area; and

(d)the availability of measurements on critical elements within the synchronised region or the synchronous area.

4.Notwithstanding paragraph 3, where the size of the synchronous area concerned and the real time situation allow it, the TSOs of the synchronous area may appoint a predetermined frequency leader.

5.The TSO appointed as frequency leader pursuant to paragraphs 1 and 2 shall inform the other TSOs of the synchronous area of its appointment without delay.

6.The appointed frequency leader shall act as such until:

(a)another frequency leader is appointed for its synchronised region;

(b)a new frequency leader is appointed as the result of resynchronisation of its synchronised region with another synchronised region; or

(c)the synchronous area has been completely resynchronised, the system frequency is within the standard frequency range and the LFC operated by each TSO of the synchronous area is back to its normal operating mode in accordance with Article 18(1) of Regulation (EU) 2017/1485.

Article 30U.K.Frequency management after frequency deviation

1.During system restoration, when a frequency leader has been appointed pursuant to Article 29(3), the TSOs of the synchronous area, other than the frequency leader, shall as a first measure suspend the manual activation of frequency restoration reserves and replacement reserves.

2.The frequency leader shall establish, after consultation with the other TSOs of the synchronous area, the operating mode to be applied on the LFC operated by each TSO of the synchronous area.

3.The frequency leader shall manage the manual activation of frequency restoration reserves and replacement reserves within the synchronous area, aiming at regulating the frequency of the synchronous area towards the nominal frequency and taking into account the operational security limits defined pursuant to Article 25 of Regulation (EU) 2017/1485. Upon request, each TSO of the synchronous area shall support the frequency leader.

Article 31U.K.Frequency management after synchronous area split

1.During system restoration, when a frequency leader has been appointed pursuant to Article 29(3), the TSOs of each synchronised region, with the exception of the frequency leader, shall as a first measure suspend the manual activation of frequency restoration reserves and replacement reserves.

2.The frequency leader shall establish, after consultation with the other TSOs of the synchronised region, the operating mode to be applied on the LFC operated by each TSO of the synchronised region.

3.The frequency leader shall manage the manual activation of frequency restoration reserves and replacement reserves within the synchronised region, aiming at regulating the frequency of the synchronised region towards the target frequency established by the resynchronisation leader, if any, pursuant to point (a) of Article 34(1) and taking into account the operational security limits set out pursuant to Article 25 of Regulation (EU) 2017/1485. When no resynchronisation leader is appointed for the synchronised region, the frequency leader shall aim at regulating the frequency towards the nominal frequency. Upon request, each TSO of the synchronised region shall support the frequency leader.