In the NEM, “DISPATCH” Periods are 5-minute periods within which (as the name suggests) the NEM is dispatched – i.e. AEMO estimates at the beginning of each 5-minute period what the demand will be at the end of the period, and dispatches generation in bid-stack order to meet this anticipated demand.
Thus, there are 288 dispatch intervals in every day (24 x 12). The DISPATCH price for (say) 14:05 applies over the period 14:00:01 to 14:05:00 (but is not used in a practical sense). This price is set at around 14:01.
“TRADING” periods are half-hour periods (48 per day) that are used (as the name suggests) to encapsulate the commercial functions of the NEM.
Hence, in practice, the TRADING price for 14:30 is paid to generators for all the energy they produce into the NEM over the half-hour period 14:00:01 to 14:30:00. Likewise, it’s also the price paid by wholesale customers (which are mostly the retailers) for the energy consumed over the half-hour.
This trading price is the time-weighted average of the 6 x 5-minute prices in the dispatch intervals making up the trading period. Hence, the trading price is only known about 26 minutes into the trading interval.
NEM-Watch provides updates of both DISPATCH and TRADING data, so it pays to be aware of which data set you are looking at!
Some data sets (like price, regional demand, regional available generation, and transmission flows, are published in real-time by AEMO (and hence updated in NEM-Watch).
Other data sets (e.g. generation output and generation availability) are deemed confidential and so are only released on the following day. For this reason, these data sets are not updated in NEM-Watch – but some are accessible through the companion product NEM-Review, which is explained on its own portal:
Feel free to trial this one as well!
Further information about this data is available on these pages: