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Network load management Network load management

Information as at 23 July 2017   6:42 a.m.

Current loading and load management measurements

Orion normally controls load to keep it just below our network limit (currently 575 MW ).  We also control load for other reasons, including to avoid localised peaks, to limit our contribution to the region load on the national transmission grid, or in response to faults or emergencies.

Network load Shedding Uncontrolled load Shedable Restorable Temperature
345 MW 0 % 346 MW 47 MW 0 MW 5 °C

Pricing periods

A significant proportion of our costs are driven by the need to meet peak loading demands.  To ensure that consumers make appropriate decisions about when and where to use electricity, we signal this cost driver in our delivery charging via the use of peak periods (for general connections) and control periods (for major customer connections).  Our regular load management tends to flatten out any peaks, so we calculate “uncontrolled load” (our estimate of the loading levels that would have occurred if we had not controlled load) and use this to trigger our pricing periods.  We adjust the on and off trigger points throughout the year to focus on the periods of highest loading without exceeding our target annual duration.  The current trigger points and status of pricing periods are:

  Current
uncontrolled
On
(MW)
Off
(MW)
Group Status Current period
duration (min)
Major customer control period 346 MW 595 575 1 Off 0
      2 Off 0
General connections peak period 346 MW 590 570   Off 0
Generation period         Off 0

Note that pricing periods have minimum durations and our system has load checks to ensure stable operation of the signals – this results in delays for a pricing period to turn on or off once the trigger is reached.

Load Graphs

The following graphs show our current load and load management activities, or you can use the date selector to view graphs from previous days.
Note that the network limit (the black line) is set as a target to keep costs and prices down. The network can cope with higher loading levels, but we will then need to invest in more capacity to maintain an appropriate buffer for growth and security.
Also note that the uncontrolled load (the red line) is not the actual loading level – it’s an estimate of the loading level that would have occurred if we hadn’t tried to keep it down.

Select date to graph:
v
The Orion's network load and load management chart showing PercentShed series, Uncontrolled series, NetworkLoad series, Limit series, ControlPeriod series, PeakPeriod series, GenerationPeriod series.
                
The Network load, upper South Island region load and temperature chart showing NetworkLoad series, USILoad series, Temperature series.

Water heating (residential)

Our load management primarily focuses on storage water heating, where supply can be interrupted for a period of time without affecting the availability of hot water.  Our control simply delays the heating of water cylinders until the peak load or network constraint has passed.  To ensure that customers are not adversely affected by our load management activities, we agree a set of long term service level targets with electricity retailers.  We then aim to limit load (and therefore delivery costs and charges) to the maximum extent possible without breaching these agreed service level targets - this is a challenging cost/quality trade-off to achieve, and we actively report on our results.

The following tables show the extent of shedding for residential and business customers with water heating linked to an ‘economy’ or ‘composite’ electricity option. Customers with night option or night with an afternoon boost are not affected by this load control. Numbers in the table are in hours and minutes.

Residential load management channels
Service level target: No more than 4 hours off in any 8 hour period
Performance: Average duration
(hours off)
Longest duration
(hours off)
In the last 8 hours (see graph) 0:00 0:00
In any 8 hour period today 0:00 0:00
In any 8 hour period yesterday 0:00 0:00

The following spreadsheet shows a history of residential water heating service performance:

Residential water heating service performance history (xslx)

The Residential shedding chart showing PercentShed series, PercentShedPrev series, Average series, Longest series, ServiceLimit series.