Paper for Business Requirements Working Group The National Smart Metering Program and the AS4755 Appliance Interface: Establishing a Direct Connection Background The Terms of Reference of the Businesses Requirements Working Group include: Item (n) recommend to the MCE how direct load control capability can be integrated into priority appliances - this analysis should be undertaken in conjunction with the existing appliance energy standards work currently being conducted by both the Equipment Energy Efficiency (E3) Committee of the National Framework for Energy Efficiency, and Standards Australia (NSSC BRWG Terms of Reference, 11 Dec 2008). This paper presents a proposal which addresses the MCE s request. In 2004 the E3 Committee began to investigate the potential for air conditioners and other major appliances to receive and respond to demand response (DR) signals from electricity utilities, as a low-cost way of managing critical peak loads. The motivation was the surge in household air conditioner ownership, which is projected to exceed 70% of households by 2020 (Figure 1). If appliance manufacturers incorporate interfaces in their products, utilities can connect to them by a range of physical pathways (eg wireless, powerline carrier, cable or internet) in the confidence that the final link can be made at low cost and the appliance will respond in a predictable way. It is then up to the utilities to negotiate the required degree of control over the appliance by offering customers pricing or other incentives. The aim of AS4755 is to set standards for physical connections to the appliance and a minimum level of DR functionality. It deliberately avoids defining standards for Home Area Networks (HANs), which represent only one of many possible pathways for Remote Agents to communicate with appliances. Australian Standard AS4755.3.1 for the air conditioner interface was published in 2008. Several local manufacturers have begun to incorporate the interface in their products, and the E3 Program is planning to make the interface mandatory in all air conditioners sold from 2012 (subject to a Regulation Impact Statement). At present work is proceeding on similar interfaces for swimming pool pumps, which also contribute to summer peak loads, and electric, solar-electric and heat pump water heaters, which have historically been connected to off-peak tariffs but which could migrate to the new control platform. In fact, it is COAG policy to phase out large electric resistance storage water heaters from 2012, so the legacy off-peak water heating load will gradually disappear. 1 1 See http://www.coag.gov.au/coag_meeting_outcomes/2009-07- 02/docs/Energy_efficiency_measures_table.pdf Measure 2.2.4, p19. V3.doc 1
These three appliance types were selected because they contribute significantly to peak demand, are readily curtailable at times of peak demand, and/or (in the case of pumps and water heaters) can offer time-shifting or energy storage services when renewable energy availability is high or demand is low (Table 1). Also, air conditioners, pool pumps and water heaters are permanently installed in the dwelling, so any inbuilt DR capability will be retained at the site even if customers move. This is not the case with portable appliances such as whitegoods, where the scope for curtailment or time-shifting is much lower, and even if a DR capability is established it may well be lost when the customer moves house. The next customer may not have the appliances or the HAN components required to re-establish the capability. Proposal for a Direct Pathway Between the Meter and the Appliance Interfaces It is already possible for electricity utilities or other Remote Agents to access the AS4755 appliance interface by means of a Demand Response Enabling Device (DRED), which receives DR signals and manages functions such as cycling routines (ie on/off sequences) and randomisation to avoid demand surges from restarting products. Trials using a range of communications strategies including ripple control and FM wireless have been completed and more are under way. This DR strategy, which does not require the presence of a smart meter, is indicated as Pathway 1 in Figure 3. Smart meters, if present, could access the DR potential of the AS4755 interface via a HAN (Pathway 2 in Figure 3). This presupposes that: 1. The Smart Meter will provide an interface to the HAN via an open standard; 2. Householders will install HANs (most likely at their own expense); and 3. The HAN will be able to interact with the target appliances, via HAN-to- AS4755 interfaces (if available on the market, and if installed). The focus of the NSSC work on the HAN interface has been on the first of the above factors. Once the technical issues are resolved, the actual implementation of DR via this pathway will still depend on factors 2 and 3. 2 As there may well be competing products and protocols, it will require some effort to ensure that the HAN components are compatible with each other and with the appliances, so there is a risk that these factors will not be present. There are also equity issues relating to the need for customers to purchase additional HAN equipment. This could prevent low-income households from taking advantage of the incentives which utilities may offer for participation in DR programs. These risks can be minimised by establishing a direct pathway between the smart meter and the AS4755 interfaces (Pathway 4 in Figure 3). This is possible because: 2 One set of issues relates to the potential for conflicting instructions from different HAN users: eg the Remote Agent using the smart meter and other parties with access to the HAN, including the customers themselves (see Pathway 3 in Figure 3). V3.doc 2
Opto-electric relays, are available at sufficiently low price to consider making them standard on all meters; Some models of meter on the Australian market already have space on the casing for two, three or possibly more opto-electric relays; Three relays could directly access the three DR modes for air conditioners in AS4755.3.1 (ie off/on cycling. 50% power limit and 75% power limit). This would give the Remote Agent fine-grained, graduated control over at least one air conditioner at the meter site; Alternatively, the relays could communicate directly with separate AS4755 interfaces, giving simple on/off cycling control over as many appliances as there are relays. The choice of which Demand Response Mode (DRM) to access on which appliance could be made at each site according to the characteristics of the appliances present (Table 1), the priorities of the Remote Agent and any local network constraints; Communication between the meter and the AS4755 interfaces could be established via cable, or via wireless or power-line carrier links using signal converters. About 75% of the new residential air conditioner load installed each year is wired to the switchboard and a further 10% is on a dedicated GPO circuit, so there would be very little additional cost in running a control cable alongside the power cable from the air conditioner position to the switchboard, to connect with a pre-existing (or future) smart meter. This arrangement would be simple, reliable and cheap. It would ensure that a degree of demand response would be immediately available as soon as a smart meter and at least one AS4755-compliant product is present. Basic DRED functions (cycling, randomisation etc) are to be incorporated in the smart meter in any case to support Function 8/14, so no additional DRED, HAN or other equipment would be required. Most of the available peak load reduction potential in the household sector could be accessed through Pathway 4 alone. However, householders could access additional DR options, connect additional AS4755 appliances or other smart appliances (eg clothes washers, lights etc) by installing a HAN or additional DREDs. Recommendation It is recommended that NSSC: 1. endorse the principle of incorporating two or more AS4755-compatible relays in the basic Smart Meter technical specification; 2. recommend to MCE that this is the preferred pathway for direct load control capability to be integrated into priority appliances (addressing TOR item (n)). ***** V3.doc 3
Table 1 Demand and Load-Shifting Characteristics of Appliances, and corresponding Demand Response Mode (DRM)(a) Electrical products covered by AS4755 (b) Potential to impact on summer peak demand Potential to Impact on winter peak demand Potential to time-shift energy use Refrigerative air conditioner Yes; DRM 1,2,3 Yes if heating; No (c) DRM 1,2,3 Pool pump Yes; DRM 1,2 Yes; DRM 1,2,3 Yes; DRM 4 Electric resistance water heater Yes; DRM 1,2,3 Yes; DRM 1,2,3 Yes; DRM 4 Heat pump water heater Yes; DRM 1,2,3 Yes; DRM 1,2,3 Yes; DRM 4 Solar-electric water heater Yes; DRM 1 Yes; DRM 1,4 (d) Yes; DRM 4 (a) DRM 1 = cycling on/off. DRM 2,3 = part load operation. DRM 4 = Forced on (b) The structure of AS4755 allows the development of interface standards for additonal appliances. There has been preliminary discussion about possible coverage of Electric Vehicle Recharging Points. (c) Pre-cooling not compatible with Australian product types, patterns of AC use, dwelling thermal properties or with greenhouse gas reduction objectives. (d) DRM 4 can also be used to avoid late afternoon winter load by pre-heating. V3.doc 4
Figure 1 Air conditioner ownership, Australia 100% 90% 80% Australia Refrigerative ACs (2009 projection) % of households owning 70% 60% 50% 40% 30% Australia Refrigerative ACs (Actual and 2006 projection) Australia Evaporative Coolers (Actual and 2006 projection) 20% 10% Australia Evaporative Coolers (2009 projection) 0% 1966 1969 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 2005 2008 2011 2014 2017 2020 Figure 2 MW of new residential air conditioning load installed by type of wiring 5000 4500 MW (cooling) sold by AREMA members 4000 3500 3000 2500 2000 1500 1000 GPO/own circuit Hard wired/own circuit GPO/gen circuit 500 0 2001 2002 2003 2004 V3.doc 5
Figure 3 Alternative Pathways to Appliance Interface Remote Agents Smart Meter 2 or 3 AS4755 relays Other HAN users Pathway 3 Meter-HAN interface Pathway 2 AS4755 DRED Pathway 1 Direct connections Pathway 4 Home area network AS4755 interfaces Air conditioner Pool pump Water Heater Non-AS4755 Smart appliances (eg whitegoods) V3.doc 6