Balfour Beatty will manage the work on the 54-turbine wind farm, which is anticipated to be completed in two years.
Early enabling works started on site at the end of May this year and the main construction works began this month.
A community council liaison group has been established by SSE. It includes representatives from each community council.
The group will meet during construction to discuss any issues or concerns raised by the local communities.
The extension project, which was approved by the Scottish Government in July last year, will create an infill between the central and north sections of the existing Clyde wind farm.
It is expected to contribute about £121.1m to the Scottish economy during the construction phase.
Clyde Extension community liaison manager Kirstanne Land said: "With construction starting at Clyde extension wind farm, we are keen to continue an open dialogue with local people to manage any potential impact and disruption carefully.
"Throughout construction and operation, the Clyde extension project is expected to bring significant local benefits to the South Lanarkshire, Scottish Borders and Dumfries and Galloway regions through direct and in-direct employment, skills training and over £20m of long-term support for community projects from the community benefit fund."
Image: The Clyde development is claimed to be one of the largest single consented wind farms in Europe. Photo: courtesy of SSE.
