Dreaming of an Integrated Systems Plan

The Australian Energy Market Operator (AEMO) integrated systems plan’s most ambitious green energy scenario is already being surpassed. To sum up, what we have at the moment is a bunch of diverse aspirational ‘plans’ and opportunistic investment in battery, and wind and solar farms. Standing by the sidelines are the umpires, the Australian Energy Market Commission (AEMC), the Australian Energy Regulator (AER) and the Energy Security Board (ESB). AEMO is on the field and left in charge of what increasingly is taking on the appearance of a tenuous network, by intervening in demand control, curtailment and frequency control schemes because synchronous energy is disappearing.

Milliseconds—the new time scale

Rather than dreaming, let’s examine what might stand in the way of an integrated systems plan capable of ultimate delivering something near 100% power penetration by renewables. An alternate title might well have been ‘rms and all that jazz’ because, it’s the jazz –the one millisecond ‘jazz’ that is replacing ‘root mean square’ concepts dating from ‘steady-state’ days. With all those inverters connecting to distribution and transmission grids, steady-state conditions are disappearing. Conveniently, we still assign inverter-based resources (IBR) nice clean, sinewave voltages and currents, and make other simplifying assumptions so that we can squeeze it all into ‘rms’ thinking. The IBR, replacing synchronous generation, operate on millisecond and smaller time intervals. Controlling all that jazz and the effects on circuits requires new thinking—a real integrated systems plan. Such a plan must cover distribution as well as transmission and generation.