Managing load

Managing the load on the power network for reliable supply

Like roads, electricity networks have ‘rush hours’ where power usage peaks and network capacity is fully utilised. This often occurs on cold winter mornings or evenings when home appliance use overlaps with the start and end of the work day, or during dry summer months when farmers need to run irrigation systems.
 
To meet this need we could expand the capacity of the network – much like adding another lane to the highway to handle peak traffic loads. But this is very expensive, especially given that the additional capacity is not needed 98% of the time and would mean price increases for all consumers.

Instead we manage and reduce the load on the network during periods of peak demand by:

  • monitoring load closely and proactively managing when levels start to peak.
  • encouraging customers to heat hot water cylinders at off-peak times.
  • hot water ripple control.
  • encouraging off-peak electricity use through lower pricing.
  • offering rebates to customers who have signed up to a scheme so we can interrupt their irrigation power supply to reduce load.

The load management dashboard

The load management dashboard provides an overview of current load levels on the Orion electricity network and is useful to check:

  • Dynamic hot water control.
  • Current on and off trigger points for control periods.
  • Current status of control periods.

View the load management dashboard(external link)

Control periods

Control periods are triggered when load levels are forecast to peak. Control periods are restricted to only occur between 1 May and 31 August each year.

Control current status

The current status for control periods is shown in the second table of the dashboard and shows as on or off.  As a minimum, each peak period will run until it has covered a complete half-hour (ensuring that chargeable control and peak periods occur).

Managing hot water

We use a ripple signalling system that allows us to send signals through the electricity network to ripple receivers switching appliances like hot water cylinders on and off.

We certainly don’t want people to run out of hot water, we just want to delay the reheating by a few hours until peak electricity usage passes.

It's important to remember

  • It’s optional for customers to participate (you can opt in and out through your retailer).
  • There are alternative pricing plans that provide more water heating, or uninterrupted water heating, but prices are a little higher.
  • We have a set of service levels that we work to for management ripple control.

More about hot water control

  • The target service level is to turn off water heating for no more than 4 hours in an 8 hour period.
  • Load is only managed on about 50 days each year.
  • Management periods are usually brief, but on the coldest days we will use the four hour service level.
  • Night rate water heating is used year round to turn on water heating overnight – this doesn’t change during the winter season.

Read this document for more information about Orion ripple control options [PDF, 48 KB]

Major customers

We have a number of major customer connections on the network. Major customers can save on electricity delivery costs by managing electrical load during our peak loading times.

During periods of high electricity demand, we use ripple control signals to communicate to major customers that they are in a high price period.

This signal gives major customers the opportunity to reduce their electrical use through such means as turning off boilers, turning off freezers and running generators.

Irrigation interruption

We offer a rebate through the Irrigation Interruption Scheme, where we will interrupt the power supply to designated irrigators during capacity emergencies.

This might happen because of severe weather, network faults, or capacity shortages. Notified testing is conducted during notified irrigation seasons.
Eligibility for the scheme, which is optional for most connections with 20kW irrigation pump capacity or more, must be approved by your electricity retailer and you will need to meet specific equipment requirements.

Contact our customer support team on 0800 363 9898 for more information.

Upper South Island load management

This project is operated by Orion and allows distributors in the upper South Island region to work together to effectively manage the peak loads on Transpower’s grid.

By managing loading on the grid at peak times, the Upper South Island Load Management (USILM) Project has led to a reduction in transmission charges and the deferment of investment in additional transmission capacity.

During periods of high electricity demand, the system sheds household hot water cylinder load throughout the region using ripple control. In a grid emergency, the system can reduce water heating load on the grid rapidly to help avoid area-wide power outages.

You can see the current upper South Island network load under 'Load graphs' on our load management dashboard(external link).