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1、smart grid is a form of electricity network utilising digital technology. A smart grid delivers electricity from suppliers to consumers using two-way digital communications to control appliances at consumers homes; this saves energy, reduces costs and increases reliability and transparency. It overl
2、ays the ordinary electrical grid with an information and net metering system, that includes smart meters. Smart grids are being promoted by many governments as a way of addressing energy independence, global warming and emergency resilience issues.A smart grid is made possible by applying sensing, m
3、easurement and control devices with two-way communications to electricity production, transmission, distribution and consumption parts of the power grid that communicate information about grid condition to system users, operators and automated devices, making it possible to dynamically respond to ch
4、anges in grid condition.A smart grid includes an intelligent monitoring system that keeps track of all electricity flowing in the system. It also has the capability of integrating renewable electricity such as solar and wind. When power is least expensive the user can allow the smart grid to turn on
5、 selected home appliances such as washing machines or factory processes that can run at arbitrary hours. At peak times it could turn off selected appliances to reduce demand.Other names for a smart grid (or for similar proposals) include smart electric or power grid, intelligent grid (or intelligrid
6、), futuregrid, and the more modern intergrid and intragrid.edit GoalsIn principle, the smart grid is a simple upgrade of 20th century power grids which generally broadcast power from a few central power generators to a large number of users, to instead be capable of routing power in more optimal way
7、s to respond to a very wide range of conditions, and to charge a premium to those that use energy during peak hours.edit Respond to many conditions in supply and demandBroadly stated, a smart grid could respond to events which occur anywhere in the power generation, distribution and demand chain. Ev
8、ents may occur generally in the environment, e.g., clouds blocking the sun and reducing the amount of solar power or a very hot day requiring increased use of air conditioning. They could occur commercially in the power supply market, e.g., customers change their use of energy as prices are set to r
9、educe energy use during high peak demand. Events might also occur locally on the distribution grid, e.g., an MV transformer fails, requiring a temporary shutdown of one distribution line. Finally these events might occur in the home, e.g., everyone leaves for work, putting various devices into hiber
10、nation, and data ceases to flow to an IPTV. Each event motivates a change to power flow.Latency of the data flow is a major concern, with some early smart meter architectures allowing actually as long as 24 hours delay in receiving the data, preventing any possible reaction by either supplying or de
11、manding devices.1edit Smart energy demandSmart energy demand describes the energy user component of the smart grid. It goes beyond and means much more than even energy efficiency and demand response combined. Smart energy demand is what delivers the majority of smart meter and smart grid benefits.Sm
12、art energy demand is a broad concept. It includes any energy-user actions to:Enhancement of reliability reduce peak demand, shift usage to off-peak hours, lower total energy consumption, actively manage electric vehicle charging, actively manage other usage to respond to solar, wind, and other renew
13、able resources, and buy more efficient appliances and equipment over time based on a better understanding of how energy is used by each appliance or item of equipment.All of these actions minimize adverse impacts on electricity grids and maximize consumer savings.Smart Energy Demand mechanisms and t
14、actics include: smart meters, dynamic pricing, smart thermostats and smart appliances, automated control of equipment, real-time and next day energy information feedback to electricity users, usage by appliance data, and scheduling and control of loads such as electric vehicle chargers, home area ne
15、tworks (HANs), and others.edit Provision megabits, control power with kilobits, sell the restThe amount of data required to perform monitoring and switching your appliances off automatically is very small compared with that already reaching even remote homes to support voice, security, Internet and
16、TV services. Many smart grid bandwidth upgrades are paid for by over-provisioning to also support consumer services, and subsidizing the communications with energy-related services or subsidizing the energy-related services, such as higher rates during peak hours, with communications. This is partic
17、ularly true where governments run both sets of services as a public monopoly, e.g. in India. Because power and communications companies are generally separate commercial enterprises in North America and Europe, it has required considerable government and large-vendor effort to encourage various ente
18、rprises to cooperate. Some, like Cisco, see opportunity in providing devices to consumers very similar to those they have long been providing to industry.2 Others, such as Silver Spring Networks3 or Google 45, are data integrators rather than vendors of equipment. While the AC power control standard
19、s suggest powerline networking would be the primary means of communication among smart grid and home devices, the bits may not reach the home via Broadband over Power Lines (BPL) initially but by fixed wireless. This may be only an interim solution, however, as separate power and data connections de
20、feats full control.edit Scale and scopeEuropes SuperSmart Grid, as well as earlier proposals (such as Al Gores continental Unified Smart Grid) make semantic distinctions between local and national grids that sometimes conflict. Papers 6 by Battaglini et al. associate the term smart grid with local c
21、lusters (page 6), whereas the intelligent interconnecting backbone provides an additional layer of coordination above the local smart grids. Media use in both Europe and the US however tends to conflate national and local.Regardless of terminology used, smart grid projects always intend to allow the
22、 continental and national interconnection backbones to fail without causing local smart grids to fail. They would have to be able to function independently and ration whatever power is available to critical needs.edit Municipal gridBefore recent standards efforts, municipal governments, for example
23、in Miami, Florida7, have historically taken the lead in enforcing integration standards for smart grids/meters. As municipalities or municipal electricity monopolies also often own some fiber optic backbones and control transit exchanges at which communication service providers meet, they are often
24、well positioned to force good integration.Municipalities also have primary responsibility for emergency response and resilience, and would in most cases have the legal mandate to ration or provision power, say to ensure that hospitals and fire response and shelters have priority and receive whatever
25、 power is still available in a general outage.edit Home Area NetworkA Home Area Network, or home grid, extends some of these capabilities into the home using powerline networking and/or RF using standards such as ZigBee, INSTEON, Zwave, WiFi or others. In the smart grid, NIST is promoting interopera
26、bility between the different standards. OSHAN8 is one initiative that enables interoperability in the home.Because of the communication standards both smart power grids and some Home Area Networks support more bandwidth than is required for power control and therefore may cost more than required. Th
27、e existing 802.11 home networks generally have megabits of additional bandwidth for other services (burglary, fire, medical and environmental sensors and alarms, ULC and CCTV monitoring, access control and keying systems, intercoms and secure phone line services), and furthermore cant be separated f
28、rom LAN and VoIP networking, nor from TV once the IPTV standards have emerged.A number of companies have entered the Home Area Network space, such as Plug Smart, a brand of Juice Technologies, LLC, Tendril, Control4, and EnergyHub.Consumer electronics devices now consume over half the power in a typ
29、ical US home. Accordingly, the ability to shut down or hibernate devices when they are not receiving data could be a major factor in cutting energy use, but this would mean the electric company has information on whether a consumer is using their computer or not.Other key devices that could aide in
30、the utilities efforts to shed load during times of peak demand include air conditioning units, electric water heaters, pool pumps and other high wattage devices. In 2009, smart grid companies may represent one of the biggest and fastest growing sectors in the cleantech market 9. It consistently rece
31、ives more than half the venture capital investment.In 2009 President Barack Obama asked the United States Congress to act without delay to pass legislation that included doubling alternative energy production in the next three years and building a new electricity smart grid.10 On April 13, 2009, Geo
32、rge W. Arnold was named the first National Coordinator for Smart Grid Interoperability.edit What a smart grid isThe function of an Electrical grid is not a single entity but an aggregate of multiple networks and multiple power generation companies with multiple operators employing varying levels of
33、communication and coordination, most of which is manually controlled. Smart grids increase the connectivity, automation and coordination between these suppliers, consumers and networks that perform either long distance transmission or local distribution tasks.Transmission networks move electricity i
34、n bulk over medium to long distances, are actively managed, and generally operate from 345kV to 800kV over AC and DC lines.Local networks traditionally moved power in one direction, distributing the bulk power to consumers and businesses via lines operating at 132kV and lower.This paradigm is changi
35、ng as businesses and homes begin generating more wind and solar electricity, enabling them to sell surplus energy back to their utilities. Modernization is necessary for energy consumption efficiency, real time management of power flows and to provide the bi-directional metering needed to compensate
36、 local producers of power. Although transmission networks are already controlled in real time, many in the US and European countries are antiquated11 by world standards, and unable to handle modern challenges such as those posed by the intermittent nature of alternative electricity generation, or co
37、ntinental scale bulk energy transmission.edit Modernizes both transmission and distributionA smart grid is an umbrella term that covers modernization of both the transmission and distribution grids. The modernization is directed at a disparate set of goals including facilitating greater competition
38、between providers, enabling greater use of variable energy sources, establishing the automation and monitoring capabilities needed for bulk transmission at cross continent distances, and enabling the use of market forces to drive energy conservation.Many smart grid features readily apparent to consu
39、mers such as smart meters serve the energy efficiency goal. The approach is to make it possible for energy suppliers to charge variable electric rates so that charges would reflect the large differences in cost of generating electricity during peak or off peak periods. Such capabilities allow load c
40、ontrol switches to control large energy consuming devices such as hot water heaters so that they consume electricity when it is cheaper to produce.edit Peak curtailment/leveling and time of use pricingTo reduce demand during the high cost peak usage periods, communications and metering technologies
41、inform smart devices in the home and business when energy demand is high and track how much electricity is used and when it is used. To motivate them to cut back use and perform what is called peak curtailment or peak leveling, prices of electricity are increased during high demand periods, and decr
42、eased during low demand periods. It is thought that consumers and businesses will tend to consume less during high demand periods if it is possible for consumers and consumer devices to be aware of the high price premium for using electricity at peak periods. This could mean making trade-offs such a
43、s cooking dinner at 9pm instead of 5pm. When businesses and consumers see a direct economic benefit of using energy at off-peak times become more energy efficient, the theory is that they will include energy cost of operation into their consumer device and building construction decisions. See Time o
44、f day metering and demand response.According to proponents of smart grid plans,who? this will reduce the amount of spinning reserve that electric utilities have to keep on stand-by, as the load curve will level itself through a combination of invisible hand free-market capitalism and central control
45、 of a large number of devices by power management services that pay consumers a portion of the peak power saved by turning their devices off.edit Platform for advanced servicesAs with other industries, use of robust two-way communications, advanced sensors, and distributed computing technology will
46、improve the efficiency, reliability and safety of power delivery and use. It also opens up the potential for entirely new services or improvements on existing ones, such as fire monitoring and alarms that can shut off power, make phone calls to emergency services, etc.edit US and UK savings estimate
47、s and assumptions behind themOne United States Department of Energy study calculated that internal modernization of US grids with smart grid capabilities would save between 46 and 117 billion dollars over the next 20 years12. As well as these industrial modernization benefits, smart grid features co
48、uld expand energy efficiency beyond the grid into the home by coordinating low priority home devices such as water heaters so that their use of power takes advantage of the most desirable energy sources. Smart grids can also coordinate the production of power from large numbers of small power produc
49、ers such as owners of rooftop solar panels an arrangement that would otherwise prove problematic for power systems operators at local utilities.The above vision makes two assumptions. First, that they will act in response to market signals and there needs to be some sort of telecommunications network. In the UK, where consumers have for nearly 10 years had a choice
