Differences between INITIALMW and Totalcleared

[Dora]

Hi Nick,

I am working with the DISPATCHLOAD data, and I am confused by the differences between the 'INITIALMW' and 'TOTALCLEARED'. 

I read the descriptions and I understand that one is the initial MW at the start of a period, and the other is the target MW for the end of a period. 

When I look at the data, for a battery for instance, the INITIALMW value and TOTALCLEARED value aren't the same for a time period. The INITIALMW can be a number and the TOTALCLEARED can be zero. 

Could you help me to understand their differences, please? 

Regards, 

Dora

[Josh Hurley]

Hi Dora,

You can find the definitions here: AEMO | Nemweb data

INITIALMW: Initial MW at start of period. Negative values when Bi-directional Unit start from importing power, otherwise positive

TARGETMW: Target MW for end of period. Negative values when Bi-directional Unit is importing power, otherwise positive.

What this means in practice is: INITIALMW is the power output/input at the start of the 5-min trading interval; TARGETMW is what the generator expects to ramp up/down to at the end of the 5-min trading interval (though doesn't always do this in practice e.g. if solar or wind farm - see the next 5-minute interval INITIALMW for what actually occurred at the end of the last inteval).

Cheers,

Josh

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[Shan He]

Hi Josh, 

Thank you so much for your quick response! Could you check if my understanding is correct, please?

Attached is the screenshot of the DISPATCHLOAD data for a battery unit (in the generation direction) on 1/1/2024. 
At 0:05, the initial MW is 5.943 and the total cleared is 2. That means the battery was discharging 5.943 MW at 0:05, and expected to ramp down to 2 MW at 0:10. 
At 0:10, the initial MW is 2.811, which means the battery wasn't not able to ramp down to exactly 2 MW as expected or required, but was able to ramp down to 2.811 MW -- close to 2 MW.

Is my interpretation of this data correct, please? 

[Josh Hurley]

Hi Dora,

That is correct. One additional thing to note is that INITIALMW is an instantaneous measure and doesn't give insight into what occurred during the 5-minute period e.g. the ramping may not have been linear. You can get more detailed data at a 4 second interval (used to calculate frequency / ancillary service costs) - I can't recall which dataset that is.

Cheers,

Josh

[Shan He]

Hi Josh, 

Thank you so much for bring this up — I was wondering how stable the MW is in the 5-minute interval for a given unit. I was looking for the 4s scada data, but I found it difficult to find reliable or consistent data. 

I can find 4s scads values for FCAS units in the Causer pays data tables (https://nemweb.com.au/Reports/CURRENT/Causer_Pays/). However, these data is only available from 13 May this year, or before 2017 (which isn’t very useful). 

I found another dataset which might be relevant: FPP_UNIT_MW. But the measurement is roughly for every 20 seconds. 

Could you advise if I was looking at the right places, or if there is something I am not aware of yet? 

Thank you so much for taking your time to answer my questions! 

Regards, 
Dora

On 11 Jul 2025 at 11:46 AM +1000, Josh Hurley <joshhu...@gmail.com>, wrote:

Hi Dora,

That is correct. One additional thing to note is that INITIALMW is an instantaneous measure and doesn't give insight into what occurred during the 5-minute period e.g. the ramping may not have been linear. You can get more detailed data at a 4 second interval (used to calculate frequency / ancillary service costs) - I can't recall which dataset that is.

Cheers,

Josh

On Thu, 10 Jul 2025 at 14:09, Shan He <dora.s...@gmail.com> wrote:

Hi Josh, 

Thank you so much for your quick response! Could you check if my understanding is correct, please?

Attached is the screenshot of the DISPATCHLOAD data for a battery unit (in the generation direction) on 1/1/2024. 
At 0:05, the initial MW is 5.943 and the total cleared is 2. That means the battery was discharging 5.943 MW at 0:05, and expected to ramp down to 2 MW at 0:10. 
At 0:10, the initial MW is 2.811, which means the battery wasn't not able to ramp down to exactly 2 MW as expected or required, but was able to ramp down to 2.811 MW -- close to 2 MW.

Is my interpretation of this data correct, please? 

<Screenshot 2025-07-10 at 3.59.35 pm.png>

[Josh Hurley]

Hi Dora,

The Causer Pays system transitioned to the new FPP system - please see nemweb.com.au - /Reports/Current/FPPRATES/

Cheers,

Josh

[Dora]

Hi Josh, 

Thank you so much for your quick response! Could you check if my understanding is correct, please?

Attached is the screenshot of the DISPATCHLOAD data for a battery unit (in the generation direction) on 1/1/2024. 

At 0:05, the initial MW is 5.943 and the total cleared is 2. That means the battery was discharging 5.943 MW at 0:05, and expected to ramp down to 2 MW at 0:10. 

At 0:10, the initial MW is 2.811, which means the battery wasn't not able to ramp down to exactly 2 MW as expected or required, but was able to ramp down to 2.811 MW -- close to 2 MW.

Is my interpretation of this data correct, please? 

 

[Josh Hurley]

Hi Dora,

That's correct.

Josh

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