JD, the initial battery stabization at Hornsdale Power Reserve was put into operation in November of 2017.  It has been upgraded since then:

"The first 100MW/129MWh was completed in November 2017. In its first two years of operation the Hornsdale Power Reserve confirmed the benefits associated with grid-scale batteries in the National Electricity Market and saved South Australian consumers over $150 million."

https://hornsdalepowerreserve.com.au/

Okiedo