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DRED
IS HERE!
DRED stands for Demand Response Enable Device. It’s a system
whereby energy suppliers can switch off or reduce the amount
of power drawn by domestic air conditioners. Virtually every air
conditioner sold today is a DRED and is said to be DRM-compatible.
W
ith the ever increasing use of air conditioners, a elsewhere but it used to be done for different reasons than
growing population and a reduction in National insufficient power generation.
Electric hot water heaters and certain storage heaters (heat
Electricity Market generation capacity over the
last five years, Australia’s electrical grid simply cannot cope banks) used to be powered by “off peak” electricity which
with the peak demands in summer. When that happens, it was much cheaper but only available at times (mostly at
means rolling blackouts (they call it “load shedding”) for night) when power demand was low.
As well, electricity suppliers needed a way to sell their
many thousands of consumers in the affected cities.
An alternative way to shed load is to only turn off power power so they could keep their coal-fired generators runto selected high power consumption appliances such as air ning at maximum power and efficiency continuously, since
conditioners, water heaters and pool pumps while leaving it is not feasible to shut them down.
In Australia, the off-peak
lower power consumption
switches were originally
devices such as lights, telconnected to a time clock
evisions and computers
but in 1953 a (typically)
unaffected.
Zellweger brand switching
This concept is known
device was introduced to
as energy demand manageprovide that function.
ment (or demand manageThese work by respondment, demand-side maning to a “ripple signal” imagement or demand-side
posed on the transmission
response) and is implelines by the electricity remented through a device
tailer.
known known in Australia
Obviously there would
as the Demand Response
be a huge problem if an
Enable Device with the
entire city’s electric heatvery appropriate sounding
ers came on at once so the
acronym of DRED.
When you buy an air conditioner in Australia or NZ you can
various electricity retailEnergy demand manage- see which demand response modes are supported from the
ment requires that appli- energy rating label at lower-right – in this case, all three modes. ers switch them at random
times during during off
ances to be disconnected So if connected, the supply authorities can throttle your air
peak periods.
during a load shedding conditioner down, by 25%, 50% or to near-useless (fan only
Where smart meters
event have a special con- running, no compressor).
are installed, these have
troller that can receive a
signal from a utility company to turn them off or to reduce a separate output, called “Controlled Off-Peak” which
performs the same function to switch
their power consumption.
on the heating elements in hot-water
The concept of energy demand
By Dr DAVID MADDISON storage tanks.
management is not new in Australia or
14 Silicon Chip
siliconchip.com.au
SIGNAL FROM UTILITY TO DRED
BY ANY METHOD AS DETERMINED
BY MARKET PLACE:
RIPPLE SIGNAL, INTERNET, ZIGBEE, ETC
UTILITY
Some manufacturers are making a feature out of DRED
– but we wonder how many consumers will think it a
positive feature when they’re sweltering with a nonworking, or only partly working, air conditioner?
Origins of DRED
The origins of DRED come from Commonwealth energy
efficiency initiatives dating from 1992, which have since
been managed by a number of different departments. These
same initiatives are also responsible for mandatory energy
efficiency ratings on various appliances.
In 2004, there were electricity supply problems which
were blamed on excessive loads caused by air conditioning, so the Equipment Energy Efficiency (E3) Committee
For many decades, supply authorities have been able to
switch “off peak” hot water systems on and off with tonecontrol systems such as this Zellweger-Uster ripple control
receiver. They superimpose a 1050Hz tone on the mains
supply which is detected by this receiver to allow the hot
water system to use cheaper, off-peak power.
siliconchip.com.au
DRED
LEFT TO MARKET PLACE
PHYSICAL AND
FUNCTIONAL
INTERFACE AS
PER AS4755
AIR
CONDITIONER
(STANDARDISED
INTERFACE)
Scheme for DRED showing how only the interface to the air
conditioner or other device is standardised. The
communications protocol and design of the DRED signal
receiver is left to the marketplace.
of Commonwealth, State, Territory and New Zealand officials was asked to examine the issue.
They concluded that energy efficiency gains alone would
not solve the problem and only “direct management of air
conditioner operation during the peaks would be effective”. Apparently, the option of allowing the marketplace
to provide a sufficient amount of power generation to meet
demand was not considered.
In 2005, Standards Australia set up a committee to look
at the issue and published a standard. In its current version this standard is known as AS/NZS 4755.3.5:2016 “Demand response capabilities and supporting technologies
for electrical products – Interaction of demand response
enabling devices and electrical products – Operational instructions and connections for grid-connected electrical
energy storage (EES) systems” and has also been expanded
to include electrical storage systems such as batteries in
homes and businesses.
This standard is a world first for this type of technology
and is under the auspices of the Australian Department of
Climate Change and Energy Efficiency.
The aim of the standard is to provide an interface on selected appliances such as air conditioners that will allow
remote demand management by the electricity suppliers
during peak loads. This could be used on a hot day when
the grid is running at maximum capacity due to the number of air conditioners in use. Users who are part of the
program will have their devices shut down or reduced in
their power settings in order that the grid is not overloaded.
Customers are typically provided with an incentive to
install DRM-compatible air conditioners. Examples are Energex offering $100 to $400 for “PeakSmart” air conditioners, Ergon offering $150 to $500 and Ausgrid $150 to $400
for their “CoolSaver” program. A video on PeakSmart air
conditioners can be seen at “PeakSmart air-conditioning”
via siliconchip.com.au/l/aace
In accordance with the Australian Standard, conforming
appliances must be able to enter certain “demand response
modes” or DRMs. DRM1 is compulsory for air conditioners
while DRM2 and DRM3 are optional. Most air conditioners
now being sold in Australia are compatible with all three
modes, which are as follows:
DRM1: The appliance is either shut down or running at
a minimal load. In an air conditioner, the compressor
would be turned off but the fan would continue to operate. Appliances that are only either off or on such as
non-variable speed pool pumps would be turned off.
April 2017 15
One way by which a DRED controller is connected to a
compatible Samsung air conditioner. There are individual
signal wires to switch specific DRM modes connected to a
terminal block. Other DRED controllers are connected to
the air conditioner by an RJ45 connector (the type used on
computer network cables).
DRM2: The appliance is operated at 50% load if it is a variable output device such as an air conditioner. Physically,
this typically means the compressor speed is reduced until it is running at 50% of its nominal full power rating.
DRM3: As for DRM2 but the appliance runs at 75% load.
This mode was requested by power companies as an
incentive to encourage customer uptake of DRED appliances as it was thought no one would want an air conditioner running at only 50% capacity.
There is a futher mode, DRM4, which switches an appliance on even if it over-rides timers or other settings. The
purpose of this setting is to force appliances to come on
when “green” energy is available so they can be run with
lower CO2 emissions. It is not used on air conditioners.
There are also other DRM modes that relate to control
of solar panels connected to grid-tied inverters to control
their power production These are specified in AS/NZS
4777.2:2015 “Grid connection of energy systems via inverters – Inverter requirements”.
The AS4755 standard is actually quite vague and only
specifies details of connections to an appliance and control of the appliance. Communication from the power utility company to the customer’s signal receiver connected
to an appliance is open to whatever method the service
provider wishes to use.
Communication may be by a ripple signal imposed on
the power lines, which seems to have been implemented
(at least in some installations) by Energex in Queensland.
Ausgrid in trials have used a mobile network 3G device
as the signal receiver.
Control may also be via a customer’s Internet connected wireless network, broadcast wireless signals, Zigbee,
Z-Wave (a home automation protocol) or mesh wireless.
Some air conditioners have some sort of indicator to show
they are in DRED mode although not necessarily the particular DRM state they are in. For example, one Panasonic
model has the power light flash for three seconds on and
0.5 seconds off, on a certain Mitsubishi model the “run”
and “timer” light blink alternately, on Hitachi models all
indicator lights on the head units flash.
One of a number of available lists of DRED compatible
air conditioners is available via siliconchip.com.au/l/aacf
Some units already have the controller built in, others are
ready for it and can have a controller and signal receiver
installed.
Presumably, if the DRED service was installed but no
longer wanted, because, for example, a sick or frail person
needed to be kept in appropriate comfort, then one would
have to get permission from the power company to remove
it and possibly refund the incentive. A licensed contractor
would need to remove the DRM connections to the appliance which should disable it since the control wires are
“add on” and DRED control is not currently embedded in
the hardware and firmware of the air conditioner.
DRED is a voluntary now but as our electrical grids become more compromised by intermittent renewable energy
sources, will it become compulsory in the future?
References
These “shortlinks” will expand to take you to the full
website:
siliconchip.com.au/l/aacg
siliconchip.com.au/l/aach
siliconchip.com.au/l/aaci
Installation of DRED devices and signal receivers is only
permitted by qualified personnel but if you are interested in
some of the details of what is done you may refer to some
of these installation guides and videos.
siliconchip.com.au/l/aacj
siliconchip.com.au/l/aack
siliconchip.com.au/l/aacl
SC
Intelligy Demand Response Enabling Device (DRED). It
communicates with a smart meter using ZigBee and can
be used to control air conditioners, pool pumps and water
heaters. Note that this is the signal receiving device. It has
to be connected to an appliance via an appropriate AS/
NZS 4755.3.5:2016 compliant interface or it can alternately
be connected to an auxiliary relay or contactor. A
temperature sensor can also be connected to this device.
16 Silicon Chip
siliconchip.com.au
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