Dynamic demand (electric power)
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Dynamic Demand is the name of a semi-passive technology to support
Dynamic demand is similar to demand response mechanisms to manage domestic and industrial consumption of electricity in response to supply conditions, for example, having electricity customers reduce their consumption at critical times or in response to prices.[7] The difference is that dynamic demand devices passively shut off when stress in the grid is sensed, whereas demand response mechanisms respond to transmitted requests to shut off,
The need for spinning reserve
The
The grid frequency is a system-wide indicator of overall power imbalance. For example, it will drop if there is too much demand because generators will start to slow down slightly. A
This
Local load control
In principle, any
) could be used to provide a constant and reliable grid balancing service by timing their duty cycles in response to system load.Because it is possible to measure grid frequency from any
Ancillary services
The dynamic controller could also provide other ancillary services, such as aiding blackstart recovery—the ability of a power grid to be brought back to service after a power outage – if programmed with that function. Generally blackstarts are made more difficult because of the large number of reactive loads attempting to draw power simultaneously at start up when voltages are low. This causes huge overloads that trip local breakers delaying full system recovery. The dynamic controller could have these loads "wait their turn", as it were, until full power had been restored.
Another vital balancing service is ‘fast reserve’ which is the use of standby plant to replace possible lost generation (e.g. due to a failed power generator or lost power line). By shedding load quickly while the running generators spin up, then switching back in to bring the frequency back to standard, dynamic controllers could spare the high cost of fast reserve generators. Also the fast response speed of this method would avoid possible brownouts occurring.
The technology could also help facilitate greater use of generation from variable sources, like wind power. Demand-side techniques could be an efficient and cost-effective way to help integrate this resource onto the grid. In particular it would allow these sources to work in conjunction with virtual power reserves like municipal water towers[8] to provide a reasonably predictable dispatchable capacity.
Implementation issues
Dynamic demand devices have the potential to save considerable amounts of
On 1 March 2011, RLtec launched its Dynamic Demand frequency response service in hot water and HVAC load devices distributed across one of the UK's largest supermarket chains, Sainsbury's. This megawatt scale virtual power plant service provides commercial frequency regulating response to National Grid in the UK. The company is now called Open Energi.[9]
Frequency service and reserve service
The national grid in the UK already is a massive user of this technology at an industrial scale - up to 2 GW of load can be lost instantaneously by frequency sensitive relays switching off steelworks etc., which is matched over a 20-minute cycle by up to 2 GW of quite small emergency diesel generators. For a complete description of this complex system see for example "Emergency Diesel Standby Generator’s Potential Contribution to Dealing With Renewable Energy Sources Intermittency And Variability" - a talk by David Andrews of Wessex Water who works closely with the UK National Grid to provide this service, given at the Open University Seminar "Coping with Variability - Integrating Renewables into the Electricity System" 24 January 2006.[10]
Up to 5 GW of such diesel generation is used in France for similar purposes, but these technologies seem to be relatively unknown
UK government investigation
In August 2007, the UK government published a report outlining what potential it sees for dynamic demand technology.[13] The report stops short of recommending the government encourage its introduction. It lists a number of technical and economic barriers to its introduction and recommends these be investigated before the government encourage the use of dynamic demand. Dynamic demand is one element of a wider government investigation into technologies that can cut greenhouse gas emissions.
However, in 2009 it was announced that domestic refrigerators are now being sold into the UK incorporating a dynamic load control system.
See also
- Advanced Distribution Automation
- Distribution management system
- Demand response Dynamic demand on a smart grid
- Electricity market
- Electricity retailing
- Energy demand management
- Flexible AC transmission system
- Grid friendly
- GridLAB-D
- List of energy storage projects
- Energy Reduction Assets
References
- ^ "Dynamic Demand" (PDF). webarchive.nationalarchives.gov.uk. page 3: domestic and industrial. Archived (PDF) from the original on 2023-07-06. Retrieved 2023-07-06.
- ^ US patent 4317049, "Frequency adaptive, power-energy re-scheduler", issued 1982-02-23
- ^ US patent 7010363, "Electrical appliance energy consumption control methods and electrical energy consumption systems", issued 2006-03-07
- ^ US patent 7149605, "Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices", issued 2006-12-12
- ^ US patent 7420293, "Electrical appliance energy consumption control methods and electrical energy consumption systems", issued 2008-09-02
- ^ US patent 8073573, "Electric Power Distribution Control Methods, Electrical Energy Demand Monitoring Methods, and Power Management Devices", issued 2011-12-06
- ^ "11. Electrical energy tariff rating". Archived from the original on 2008-12-08. Retrieved 2016-01-24.
- ^ "DJ Hammerstrom et al., "Pacific Northwest GridWise™ Testbed Demonstration Projects: Part I. Olympic Peninsula Project," PNNL-17167, October 2007" (PDF). Archived (PDF) from the original on 2014-03-27. Retrieved 2012-01-28.
- ^ "Sainsbury's | Open Energi". Archived from the original on 2016-01-31.
- ^ "Coping with Variability". Archived from the original on 2006-10-10. Retrieved 2007-08-25.
- ^ "Programme | Claverton Group". Archived from the original on 2008-12-26.
- ^ "Archived copy". www.claverton-energy.com. Archived from the original on 17 February 2010. Retrieved 12 January 2022.
{{cite web}}
: CS1 maint: archived copy as title (link) - ^ "Archived copy" (PDF). Archived from the original (PDF) on 2009-06-09. Retrieved 2008-08-01.
{{cite web}}
: CS1 maint: archived copy as title (link) - ^ "BBC talks about Dynamic Demand (Smart fridges) and Smart Metering. | Claverton Group". Archived from the original on 2010-02-10. Retrieved 2009-02-10.
External links
- Dynamic Demand U.K.
- Open Energi
- A Note On the Potential Value of "Dynamic Demand" Control (in the UK/EU)
- "Frequency Control by Demand Management". National Grid. Archived from the original on 2011-06-11. Retrieved 2010-11-22.