AEMO and independent checks by Manitoba Hydro International find the “black system” was “triggered due to lack of inertia on (the) South Australian side once the Heywood interconnector tripped” and that “the cause of the black system was sustained power reduction of a number of wind farms” in SA.
Once the interconnector was tripped, the state didn’t have sufficient “system inertia” to run the grid. Keeping synchronous power generation has long been seen as a central challenge in adding renewable energy. MHI suggests SA may need to identify “must run” thermal generators to do this. In other words, if its coal-fired or gas-fired generators had still been running, the grid would have had the required inertia. These, of course, had been forced into mothballs by subsidised renewable generation.