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power to a ff o rn tu ly te mo plier could re hout your knowledge or p u s y it ic tr c if your ele itioner, wit Just imagine e such as your air cond re, because o m o n ic v e e in d g a heavy-use proval. . . Im p a r u o y n e v perhaps e 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