In January 2017 I wrote a paper that contained the reasons why the frequency control on the eastern seaboard was insufficient and poor. A summary article was published here on WattClarity on 23rd March 2017, it included the following statement:
“Reassessment of the approach to frequency control should be undertaken with a view to:
· reintroducing narrow mandated deadbands across the NEM
· removing regulatory disincentives to tight governor action.”
The paper also included an explanation of why the current method relying on “regulation FCAS” was insufficient.
After 32 months of numerous reviews, technical working groups, international expert engagement, another serious event (the double-islanding of 25th Aug 2018) and three rule changes in process the frequency control of the eastern seaboard remains extremely poor. Furthermore, the system is likely to remain poorly controlled for another summer period as rule the rule change process takes months.
The 1 November 2015 event in SA illustrated similar lack of control (the AEMO report is here) while the FCAS markets raked up $65 Mil in local costs.
In September 2018 at an Engineers Australia event on Ancillary Services and frequency control, one member in the audience asked the following question; “You spoke about this a year ago, why hasn’t it been fixed?” The question was answered by the AEMC, who politely explained that their FCAS Framework Review did not consider it an urgent problem. It was clear the engineers expected the problem to be fixed after 12 months, particularly when there are known practical solutions.
The public utilities in each state once employed a small department (about 5-6 engineers) that specialised in system dynamics and control. The system control engineers would test, measure and analyse the control responses of each unit to ensure that they responded to step changes correctly. System control engineering was concerned with co-ordinating the response of all units to ensure that unit controls were working and the collective response of the system was adequate and coherent.
The inefficiency, cost and risk to the power system of the market reviews over the last 32 months far outweigh the cost of the small dedicated teams of system control engineers that once tuned the units.
The international expert report has recommended reintroducing appropriate dead bands on all units, removing control actions that defeat frequency sensitivity, and co-ordinating droop settings across the NEM. This is logical and necessary and does not contradict the recommendations I made 32 months ago.
Even within the expert’s report I find two items that appear to be in incorrect when compared with actual local data. Electronically connected generation has been proven to not be sensitive to frequency as is claimed and operates across a wider frequency range than say a gas turbine. Furthermore, the power system is not “well controlled” when the frequency reaches the boundary of the normal operating band. The lack of control is illustrated every time a region separates, the inability to recover the frequency within a separated region is indicative of the lack of control. 25th August in Queensland illustrated this – Figure 16 from the AEMO’s report (copied below) illustrates that the control systems no longer provide an appropriate response for partial load rejection, there is insufficient reduction in active power so the frequency remains high:
The current market mechanisms force all error in active power into the frequency, with few understanding the consequences to efficiency or control.
It is clear from the evidence that the market has enabled the detuning of the generators through the cumulative effect of a number of rule changes. This has taken the system from co-ordinated control to competition in control, a highly undesirable outcome on the power system.
Over the years of reform, the rules have altered the power system control philosophy without appreciating the consequences. We see more rule changes and regulatory complexities being piled onto generators without addressing the fundamentals or understanding in full what the problem is that rules are trying to solve. The inability within the market to efficiently correct an identified technical control problem illustrates a fundamental design flaw and a significant loss in power system knowledge.
Are we suffering a system tragedy? Every issue triggers a call for a new policy, new regulation, new “technical requirement” when the fundamentals have not been addressed. Each rule change seems to bring unintended outcomes, often increasing costs and reducing efficient operation. Or do we have blind faith in the “magic of the market place”, thinking that a market knows how to control the power system?
We face another summer with the eastern seaboard at risk again with inadequate control of active power.