[Johnythree]

It behaves exactly as an un-powered (but spinning) generator.

In the industry these are known as a "Synchronous Condenser" or Syncom. They have been in use for a long time.

https://www.pv-magazine-australia.com/2019/04/06/long-read-b...

One problem with the switch to renewable energy is that the mechanical momentum in steam turbines is lost.

This leaves the grid vulnerable to rapid changes in loading.