PHILIP HOPKINS
By PHILIP HOPKINS
AGL has begun a $92 million refurbishment of the Unit 1 generator at its 2200-megawatt Loy Yang A power station as part of a maintenance program that aims to produce reliable power until the station’s closure in 2035.
The 560MW Unit 1 generator – one of four generator units at Loy Yang A – will be out of service for more than two months undergoing maintenance works and upgrades.
It will include critical asset integrity assessments, major repairs and replacements.
A key element of the outage is the refurbishment of the generator stator in Unit 1.
The stator is the stationary part of a rotary system in the generator.
Energy flows through a stator to or from the rotating component of the system. The 255-tonne stator was listed from its foundation earlier this month and replaced with a spare stator.
AGL’s chief operating officer, Markus Brokhof (who came to AGL three years ago from a Swiss power company) said the stator was transported by road to the Port of Melbourne – “a logistical challenge”, as the 255-tonne unit required special permits to travel through the city to the Port of Melbourne.
It was shipped to Rotterdam and barged down the Rhine river to Erlangen, where it will be repaired in a Siemens factory.
The refurbished stator will return to Loy Yang in late 2024 and will then become the spare.
The spare stator that has been installed was refurbished in 2018-19 and brought to the site from Germany.
Mr Brokhof – who has more than 25 years’ experience in the oil, power and gas sectors in Europe, Africa and the Middle East – said constantly swapping the generators was part of the normal ageing process of power stations.
“One of our lessons from the Unit 2 outage forced last year, was that we always wanted a fully refurbished generator to ensure that if something happens, we can immediately replace the generator,” he told the Express.
“Every six years we will refurbish the major components of the units.”
Was the damage the result of the intermittency of renewable wind and solar energy, as traditional coal-fired power stations are designed to operate continually over 24 hours?
Mr Brokhof said that was initially the thinking of power station operators.
This prompted an exchange of information with other generators in the world and specialist engineering companies on how to handle these pressures carefully.
“At end of the day, going down to minimum generation, if you do it in a proper fashion, it will not damage the unit, although it may increase wear and tear,” he said.
Mr Brokhof said Loy Yang had tested down to 300MW per unit from each’s full 560MW.
This flexibility of 260MW for each of the four units created a flexibility of more than 1000MW for the whole power station.
“This is very practical for us,” he said.
When solar energy is at its peak during the day, “we can run down to 300MW and in the evening and morning when demand is high, we go back up and extract maximum commercial value”.
AGL did the same at its Bayswater black coal power station in NSW, where flexibility of 500MW for its four units gave the station 2000MW of flexibility.
“That is the new the commercial validity; produce when power is valuable, be available when it is financially worth it,” he said.
This was particularly so in Australia, where solar penetration from rooftop solar and solar farms was the highest in the world.
Mr Brokhof said this approach would enable Loy Yang A to operate at the highest standard during the transition over the next 12 years.
“We want the highest availability. At the end of the day, the highest values we generate, they finance the transition. We need the maximum cash to finance the ambitious plan to close in 2035 and invest in our renewable capacity,” he said.
“Despite the early closure, we will run a safe and reliable operation until the end of the period.”
Mr Brokhof emphasised that to complete the refurbishment works, Loy Yang was mobilising 750 contractors and sub-contractors on the site.
“This has a substantial economic impact in the region,” he said.
“They live, eat and party in the region – a big contribution to the entire community.”
Most of the expatriates came from Melbourne, some from interstate, and expatriates from Germany and Japan.
“Loy Yang apprentices in electrical, boiler making and fitting, mostly local from Gippsland, get exposure to specialist workers and contractors,” he said.
“These are specialist maintenance tasks they would not ordinarily experience during their training.”
Key elements of the maintenance work during the outage include generator stator and rotor changeover; turbine LP rotors changeover; steam strainer works – asset integrity, inspections, replacements; turbine valve overhauls; boiler pressure parts inspection and repairs; and boiler gas outlet duct expansion joint replacement.
