The size of our Julia codebase is about 400,000 lines of code, spread over numerous internal and open source packages. You can cite the "we're hiring" slide from my Juliacon talk for that https://raw.githack.com/oxinabox/ChainRulesJuliaCon2020/main...
At the moment there's no Julia episodes yet. If you want to come on, head over to https://runninginproduction.com/ and click the "become a guest" button near the top right to get the ball rolling.
As far as I know, all ISO's in the USA use either ABB, Siemens, or GE for their market optimization software (huge systems) or basically those same vendors plus a few more for their EMS systems. There are also plenty of other amazing products for transmission planning, short term studies, and transient stability studies. More specifically, how are you linked to the system operators? When you say you optimize the grid, that could mean any one of a thousand different things. Are you providing various inputs (forecasts, risk factors, etc) that are used by some markets? Please note that I'm not questioning that y'all work with some of these entities in some fashion, I'm just trying to get a better handle on the specifics of where y'all are plugged in.