UK Grid – Visual

Where Maximum Export Limits are provided (MEL) alongside Physical Notification (FPN) & Bid Offer Acceptance Levels (BOAL) then these are shown as follows:

BOAL figures overrule both MEL & FPN. This figure is always used if it is available.

FPN > MEL = The MEL Figure is used

MEL > FPN = The FPN Figure is used

What does this mean?

MEL – Maximum Export Limit: It is the maximum power export level of a particular Unit at a particular time. A Units Maximum Export may be lower than its official rated output due to such things as maintenance, grid connection limitations, plant run up rates, low wind etc… It is therefore important to base output on the MEL figure should it be lower than the FPN figure for better output accuracy.

FPN – (Final) Physical Notification: A Physical Notification is the best estimate of the level of generation or demand that a plant operator expects a Unit to export or import in the ½ hour period. 

BOAL/BOALF – Bid-Offer Acceptance Level: is a formalised representation of the purchase and/or sale of Offers and/or Bids by the System Operator in its operation of the Balancing Mechanism. It essentially shows as a deviation (increase or decrease) of a plants output from an FPN figure to balance demand against generation. The Grid being so fluid it may at times be necessary to ramp a plant’s output up or down to “balance” the grid several times in a ½ hour period.

2 Points should be noted with this:

1: BOALs are nowhere near as common occurrence as FPNs so most of the time the FPN is likely used. 

2: BOALs are however common during times of grid stress and as such the output figure can change repeatedly in the same ½ hour period. This website picks the first BOAL figure it finds (if applicable) for each plant. This may show as some considerable drift of output against other Grid Monitoring sites by the end of the ½ hour period. It is however the most accurate plant output figure I have available at a given time which is why it overrides both MEL & FPN.

Scotland to England is measured at the crossover of the SCOTEX or B6 Boundary as below

England North to South is measured at the crossover of the B9 Boundary as below:

If you are wondering what TP (Number) stands for in the center of the graph it shows which time period the data is from (as below.) The data refreshes every half hour and increments by 1. If the number does not increment over several hours something is wrong with the data stream and/or my database (sorry!)

1: API data lag from BMRS: “API latest physical data (Near Real Time) is for current 1/2-hour settlement period + 2” -basically everything you see here is an hour out of date. If you are comparing this to other “Grid Monitor” sites
and it doesn’t add up this is normally why. (I’m working on a way around this to get nearer to realtime)

2: FPN vs MEL vs BOAL Figures: Currently all output figures above are “Physical Notifications” (FPN) from the plant. These are usually accurate HOWEVER there are occasions (such as when gradually raising load on a nuclear plant
or uncertainty on wind from an offshore windfarm) that a Plant Specific “Maximum Export Limit (MEL)” may be set
lower than the FPN. As such, the true output in this case is more likely to be nearer the lower MEL figure.  

Ultimately, I need to figure a way of choosing the lower of the two values from the data (if FPN > MEL then Plant Output = MEL…) but this is again work in progress.  Done 16/09/21

4: Solar – As far as I can find, no solar farms appear in BMRS data. If you know of any please let me know.

5: Interconnectors are a different data stream. I have it, just not implemented yet. Done 11/8/2021

6: All of this is Beta so don’t take it a 100% accurate or use it for anything critical. I’ve not spent any time tracking this data over time to make sure it’s all perfect yet. (And I’ve a lot of plant turbine/genset info to trawl
through.)