The SA experiment shows us that beyond 15% renewable inputs develops an instability in maintaining synchronous 50hz power. Fact, just before the failure 960Mw of power was generated by the various wind turbine sites. Whatever caused the shutdown there was still over 500Mw on the interconnector lines...they were still operational...they did not collapse or lose a tower. The footage on TV only shows dinki 72 or 134Kv distribution lines not the big 300Kv monsters. When the review comes out, my bet is on a distribution Lin going down BUT the damage caused when over 900Mw of wind power dropped off line causing the brown out cascade shutdown of the entire system. There was not enough synchronous generating capacity close enough to even attempt to take up enough load to allow safe load shedding to keep the system alive...This was a BLACK shutdown! Ask any engineer how bloody hard it is to bring the entire network back online without sizeable generation assets. Wind will not even connect with being able to sense a load. Same with solar.
Note, SA is now functioning. This negates the idea of a main 300Kv transmission line coming down. 21 towers repaired in 5 days? And bring the network up to synchronous power across the state? Wait for the report and watch who does the government bidding. Wind power is not base load power.
Want to make the system work? Hook all that wind power up to pumped storage hydro. Regardless of pumping losses from "free" power, this will be the only way demand power could be made available from windfall generation