Loy Yang B is about to start a 45-day planned maintenance outage as part of a $170 million generator upgrade on Unit 1.
More than 500 workers will be onsite to upgrade the turbine and replace the generator and turbine control system.
Major contractors BMC, Downer and GE had been appointed to undertake boiler, generator and main turbine upgrades.
Loy Yang B general manager Tony Hicks said there were already about 200 workers onsite carrying out pre-outage work.
He stressed the majority of the additional workforce was from Gippsland, with some outside speciality labour brought in.
Mr Hicks said the upgrade would increase the unit's capacity and reliability through the plant's operating life as well as in readiness for summer peak demand.
He said the project was the second part of a major upgrade that was undertaken on the plant's Unit 2 a year ago.
"This is a 45-day outage, it's an aspirational target but we are really confident we will achieve it," Mr Hicks said.
"It will be hard work, but we are confident, we are ahead of where we were previously with the last outage, as a lot of pre-outage work is on track."
Mr Hicks said this outage also had the added challenge of incorporating COVID-19 safety measures and hygiene controls.
Some measures included providing additional lifts, kitchen and bathroom facilities, a temperature-testing station, staggered work times and compulsory face masks.
Staff members will also be required to wear a contact tracing device imported from Germany.
"We have so many things across the site that we haven't had to deal with before, it's a big enough upgrade without having to deal with COVID-19 risks," Mr Hicks said.
"The safety of our employees is our priority, I think we've left no stone unturned with looking for effective and worthwhile measures."