As part of the process of compiling our Generator Report Card 2018, we’re taking a look at the instances where individual DUIDs were significantly Off-Target. In our longitudinal summary article today, we can’t see a clear trend emerging to suggest the overall aggregate absolute level of Off-Target is getting substantially worse, or better.
One of the reasons why a generator might be Off-Target is that (for a Semi-Scheduled plant) the AEMO’s forecast (via AWEFS or ASEFS) might have been not as we’d like it to be.
Using “Time-Travel” in our ez2view market analysis software, we’ve wound back a particular dashboard in ez2view back to the 18:35 dispatch interval on 11th August 2018, in order to show what happened in the 18:30 dispatch interval:
As noted in on the image, there was a 101MW discrepancy between the forecast (which had expected an increase in output) and the actual output (which had decreased from the prior position instead). That’s a big percentage on the output, and a sizeable deviation in absolute terms.
With the up-and-down nature of the the pattern in output across the day, one wonders whether this was wholly due to some unpredictable wind patterns, or whether there were plant-related issues (not seen in AWEFS) that led to the challenging day. There is insufficient information in the MMS currently (to our knowledge) to shed light on this.
In our Generator Report Card 2018 we are keen to understand the pattern, and trend, of these sorts of difficulties:
(a) Are some Wind or Solar Farms more difficult to is to forecast than others?
(b) Are there seasonal or locational variations?
(c) Is the situation improving over time, as the teams involved get better at the process?