AGLM's contravening conduct
51 During the BW Relevant Period, each of BW01 and BW04:
(1) produced electricity through steam turbines driven by boilers fuelled with black coal;
(2) had a mechanical governor, which is an inherent mechanical component of the turbine system that regulates electrical output and could not be turned off. This feature of the units meant that even when the frequency influence setting was "off", the units automatically provided some response to changes in local frequency (as described in paragraph 52 below), which assisted to arrest frequency deviations and stabilise network frequency; and
(3) was fitted with a frequency influence setting within the electronic DCS for the governor, which setting could be switched on and off manually by AGLM's operations personnel.
52 When switched "on", the frequency influence setting facilitated the response of the units to frequency disturbances by automatically adjusting the generating unit's MW setpoint for electricity generation such that the unit, including the steam valves and boiler controls, could operate to respond to deviations in local frequency. When switched "off", although the units' response to changes in local frequency was often able to continue for up to several minutes, the extent of the units' response would tend to diminish over time as, over time, the unit's control system would return the unit back to its unadjusted setpoint (which typically changes over time as circumstances progress).
53 As a consequence, notwithstanding that the units were capable of delivering, and did deliver some response to frequency disturbances when the frequency influence setting was "off", it was necessary for the frequency influence setting on each unit to be "on" in order to ensure that the units would provide the delayed raise service in accordance with the MASS in response to any significant frequency deviation. When the frequency influence setting was "off", the control systems for the Bayswater units could not operate to produce in all cases the appropriate quantity of delayed raise response required by the MASS, being a response proportionate to the relevant scale and duration of the significant frequency deviation.
54 Accordingly, the contraventions committed by AGLM relate only to provision of the delayed raise service, rather than all contingency FCAS services.
55 In 2018, BW01 underwent an outage to fit its new electronic DCS, which replaced its previous analogue control system, and returned to service on 3 September 2018. This was a large power station control system upgrade, with approximately 15,000 individual input/output points impacted. BW04 underwent a similar outage in 2019, and returned to service on 4 December 2019. These were both undertaken as part of a broad works program at the Bayswater power station to improve the life cycle, reliability and performance of the units and included upgrades to multiple aspects of those units beyond the electronic DCS.
56 The switch to turn the frequency influence setting on or off in the new DCS was a new function that had not previously been present on BW01 and BW04 (or on the other units at the Bayswater power station). Under the previous control system, the frequency influence function was always "on", and could not be manually switched off by an operator.
57 As part of extensive management of change work programs undertaken in order to return BW01 and BW04 to service, the frequency influence function was switched on and successfully tested on both units. However, upon their return to service, the frequency influence setting on both units was in the "off" position.
58 Upon the units' return to service, AGL's trading team was not informed that the frequency influence setting was "off" and did not check with the operations personnel. At times during the BW Relevant Period, the trading team submitted market ancillary service offers for BW01 and BW04 to provide the delayed raise service while the frequency influence remained "off". When the frequency influence was "off" the control systems for the units could not operate to produce in all cases the appropriate quantity of delayed raise response in accordance with the MASS as described in paragraph 51.
59 As a result of a fleet wide investigation that it initiated after having been notified by AEMO on 1 and 4 June 2020 of the inadequate contingency FCAS responses from the Loy Yang A units, AGLM identified on 31 July 2020 that the frequency influence setting had not been switched "on" in units BW01 and BW04. AGLM then switched the frequency influence setting back on. Both BW01 and BW04 featured a mechanical governor which automatically provided some response to changes in local frequency. This, together with the nature of contingency FCAS in which a response is only required when a relevant significant frequency deviation occurs, contributed to the issue not being detected by the AGL Group until July 2020.
60 AGLM inadvertently left the frequency influence setting switch in the "off" position on 19 August 2020 and 21 August 2020 following the conclusion of testing undertaken as part of the introduction of mandatory primary frequency response. This was identified by AGLM and the setting was switched on for both units on 25 August 2020.
61 AGLM notified AEMO and the AER of the units' non-compliance on 8 and 11 September 2020, respectively, including through the provision of detailed reports.
62 During those periods:
(1) BW01 was offered to provide the delayed raise service by market ancillary service offers for 31,661 trading intervals across 680 discrete trading days;
(2) BW01 received 130,418 dispatch instructions by which it was enabled to provide the delayed raise service;
(3) BW04 was offered to provide the delayed raise service by market ancillary service offers for 2,391 trading intervals across 53 discrete trading days; and
(4) BW04 received 12,104 dispatch instructions by which it was enabled to provide the delayed raise service,
in respect of the trading intervals and dispatch intervals when their respective frequency influence settings were "off".
63 Although the AGL Group had operational and compliance processes and practices, systems, monitoring and training programs in place, AGLE's trading personnel were unaware that the frequency influence switch was "off" for trading intervals referred to in paragraphs 62(1) and 62(3) above and did not check before offering the delayed raise service to AEMO on behalf of AGLM for those periods. This arose from a combination of the insufficiency of those practices and inadvertence in the circumstances identified in paragraphs 55 and 57 above.
64 While BW01 and/or BW04 operated with their frequency influence setting switched "off", and were enabled to provide the delayed raise service, a total of 261 significant frequency deviations occurred. Although BW01 and BW04 did provide some response to each of those frequency disturbances as explained in paragraphs 51(2) and 52 above, AGLM did not operate its equipment to ensure that those units could provide delayed raise responses to those frequency deviations in accordance with the MASS, because the frequency influence setting was "off".
65 In respect of the BW Relevant Period, the AGL Group initially received revenues of $1,922,571.83 (excluding GST) from AEMO for the delayed raise service that units BW01 and BW04 were enabled, to provide at times when the frequency influence switch was "off". After identifying and notifying AEMO of the issue, the AGL Group repaid that amount to AEMO through AEMO's standard settlement revision policy (and, where that was not possible, through a separate method it arranged with AEMO) as follows:
(1) AEMO initially recovered $39,440.00 of that amount through settlement revisions within 30 weeks after the payments were made to AGLM on 24 September 2020.
(2) The AGL Group later voluntarily repaid the remaining $1,883,131.83 (being amounts for periods earlier than the 30-week window for settlement revisions) to AEMO on 11 August 2022.
66 As a consequence of the conduct summarised in paragraphs 55 to 62 above, AGLM contravened:
(1) cl 4.9.8(a) of the NER in relation to each of the 142,522 dispatch instructions given by AEMO (130,418 dispatch instructions for BW01 and 12,104 dispatch instructions for BW04), as AGLM did not comply with those dispatch instructions, because it did not operate its equipment to ensure that those units could provide the delayed raise service that they were enabled to provide in accordance with the MASS (in circumstances where AGLM did not hold the reasonable opinion that to comply would be a hazard to public safety or materially risk damaging equipment); and
(2) cl 4.9.8(d) of the NER in relation to each of the 34,052 trading intervals (31,661 trading intervals for BW01 and 2,391 trading intervals for BW04) in which AGLM did not ensure that its generating units were at all times able to comply with the latest market ancillary service offer that it had made for each trading interval.