- Grid friendly
Electrical devices are considered grid friendly if they operate in a manner that supports electrical power grid reliability. Basic grid-friendly devices may incorporate features that work to offset short-term undesirable changes in line
frequencyor voltage; more sophisticated devices may alter their operating profile based on the current market price for electricity, reducing load when prices are at a peak. Grid-friendly devices can include major appliances found in homes, commercial building systems such as HVAC, and many industrial systems.
Most electric systems use
alternating currentwith a nominal frequency of 50 or 60 Hz ( hertz) to deliver energyproduced by electrical generators to the electricity consumers. When the amount of electric powerproduced by the generators exceeds the power used by the customers, the frequency of the electricity rises. Conversely, when the amount of electric power produced is less than what is consumed, the frequency drops. Therefore frequency is an accurate indicator of the system-wide (called "global") balance between supply and demand. Without grid-friendly frequency response, the rate at which the frequency changes is dependent principally on the system's total inertia(which is not very controllable) and the aggregate response of the generators' control systems (which can only be controlled relatively slowly). In contrast, grid-friendly devices can act very quickly.
A grid-friendly device can respond to changes in frequency by reducing or interrupting the demand for electric power (called "load") when the frequency drops below a certain threshold, and/or increasing load when the frequency rises. Although a single grid-friendly device may be a very small load, the fraction of the total load that can be controlled by frequency at any time is usually sufficient to provide under-frequency protection to the system before more drastic measures like black-outs are required.
The advantage of grid-friendly frequency response is that frequency is ubiquitous on an electric system. When a generator shuts down in one part of the system, all the loads everywhere in the system can simultaneously detect the change and respond instantly and appropriately without the need for a control system to detect the problem, a control center to make a decision, or a
telecommunications networkto deliver commands to millions of devices. This type of behavior changes frequency from a simple electrodynamicand control systems input to an emergent property. While there is still some controversy on the subject, it is believed that complex systemsutilizing self-regulation through emergence are generally more resilient and flexible than are simpler top-down command and control systems.
In contrast to frequency, voltage varies widely throughout electric systems, because it is the voltage difference between two devices that largely determines the direction and magnitude of the current (hence the power) that flows between them. Therefore voltage is a more local phenomenon, and grid-friendly devices that respond to voltage will support more local aspects of the electric delivery system.
While frequency and voltage respond to physical phenomena on the electric system, grid-friendly price response is designed to address economic phenomena. With the increasing application of electricity markets to manage the efficient distribution of electric power, more consumers are exposed to electricity prices that change over time, rather than fixed for months or years. In general, higher prices occur at times when the electric system is running short of supply. The purpose of grid-friendly price response is to promote
demand responseamong electricity consumers. Demand response is one means of reducing the market powerof electricity suppliers when production runs short. Grid-friendly response to price also allows consumers to reduce their energy costs by using less electricity when prices are high, and more electricity when prices are low.
A demonstration of grid-friendly technology was conducted for the US Department of Energy in 2006 and 2007 in the Northwest region of the United States. Participants included local utilities, residential and commercial customers, industrial loads belonging to municipalities, and a number of vendors and researchers. The grid-friendly technology demonstration showed that common residential appliances did automatically detect grid problems expressed as frequency deviations and reduced energy consumption at critical moments. The Olympic Peninsula demonstration showed that residential, commercial, and industrial loads did adjust their consumption patterns based on price signals emanating from a distribution-level market operated as a double action. Both of these projects showed how grid-friendly technologies can and do reduce pressure on the electric grid during time of peak demand.
Energy demand management
Sources and additional resources
* US Department of Energy, Office of Electricity Delivery and Energy Reliability [http://www.electricdistribution.ctc.com/index.htm]
* Grigsby, L. L., et al. The Electric Power Engineering Handbook. USA: CRC Press. (2001). ISBN 0-8493-8578-4
* S. Stoft. Power System Economics. Wiley Interscience. IEEE Press. 2002). ISBN 0-471-15040-1
* D. J. Morrow, et al. (1991). Low-cost under-frequency relay for distributed load-shedding. In proc. of 3rd Int. Conf. on Power System Monitoring and Control. 273-275.
* Z. Zhang, et al. (1999). An adaptive microcomputer-based load shedding relay. In conf. rec. of 34th IAS Annual Mtg. Industrial Applications. 3: 2065–2071.
* D. P. Chassin, et al. (2005). Estimation of WECC system inertia using observed frequency transients. IEEE Transactions on Power Systems. 20:2 1190–1192.
* Pacific Northwest National Laboratory (2007). GridWise Demonstration Project Fast Facts. [http://gridwise.pnl.gov/docs/pnnl_gridwiseoverview.pdf] .
* D. Hammerstrom et al. (2007). Pacific Northwest GridWise Testbed Demonstration Projects Part II. Grid Friendly Appliance Project. PNNL no. 17079, Pacific Northwest National Laboratory, Richland, Washington [http://gridwise.pnl.gov/docs/gfa_project_final_report_pnnl17079.pdf] .
* D. Hammerstrom et al. (2007). Pacific Northwest GridWise Testbed Demonstration Projects Part I. Olympic Peninsula Project. PNNL no. 17167, Pacific Northwest National Laboratory, Richland, Washington [http://gridwise.pnl.gov/docs/op_project_final_report_pnnl17167.pdf] .
Wikimedia Foundation. 2010.
Look at other dictionaries:
Grid friendly appliance — Appareil grid friendly Pour les articles homonymes, voir GFA. Un appareil grid friendly (Grid friendly appliance ou GFA en anglais) est un appareil électroménager capable de s enquérir de l état du réseau électrique en temps réel et de réduire sa … Wikipédia en Français
Appareil Grid Friendly — Pour les articles homonymes, voir GFA. Un appareil grid friendly (Grid friendly appliance ou GFA en anglais) est un appareil électroménager capable de s enquérir de l état du réseau électrique en temps réel et de réduire sa consommation ou de s… … Wikipédia en Français
Appareil grid friendly — Pour les articles homonymes, voir GFA. Un appareil grid friendly (Grid friendly appliance ou GFA en anglais) est un appareil électroménager capable de s enquérir de l état du réseau électrique en temps réel et de réduire sa consommation ou de s… … Wikipédia en Français
Grid-tied electrical system — A grid tied electrical system, also called Tied to grid or Grid tie system, is a semi autonomous electrical generation or grid energy storage system which links to the mains to feed excess capacity back to the local mains electrical grid. When… … Wikipedia
Smart grid — Public infrastructure … Wikipedia
State Grid Corporation of China — 国家电网公司 Type State owned enterprise Industry Power generation Founded 2002 Headquarters Xicheng District, Beijing, China … Wikipedia
Managerial grid model — A graphical representation of the Managerial Grid The managerial grid model (1964) is a behavioral leadership model developed by Robert R. Blake and Jane Mouton. This model originally identified five different leadership styles based on the… … Wikipedia
190th Fighter Squadron, Blues and Royals friendly fire incident — March 28, 2003 Two A 10 Thunderbolt jets … Wikipedia
Interactive European Grid — The Interactive European Grid project (project identifier FP6 IST 031857) started on 1 May, 2006 and will last for 24 months. The work takes place with the financial support of the European Union and identifies the Specific Research Program.The… … Wikipedia
Bicycle-friendly — describes policies and practices which may help some people feel more comfortable about traveling by bicycle with other traffic. The level of bicycle friendliness of an environment can be influenced my many factors resulting from town planning… … Wikipedia