Nonintrusive load monitoring

Nonintrusive load monitoring

Nonintrusive Load Monitoring (NILM), or Nonintrusive Appliance Load Monitoring, is a process for analyzing changes in the voltage and current going into a house and deducing what appliances are used in the house as well as their individual energy consumption. Electric meters with NILM technology are used by utility companies to survey the specific uses of electric power in different homes. NILM is considered a low cost alternative to attaching individual monitors on each appliance. It does, however, present privacy concerns.

Contents

Background and theory

Nonintrusive Load Monitoring was invented by George W. Hart, Ed Kern and Fred Schweppe of MIT in the early 1980s with funding from the Electric Power Research Institute.

Figure 1 from US patent 4858141 showing basic process for NILM

The basic process is described in U.S. Patent 4,858,141. As shown in figure 1 from the patent, a digital AC monitor is attached to the single-phase power going into a residence. Changes in the voltage and current are measured (i.e. admittance measurement unit), normalized (Scaler) and recorded (Net Change Detector Unit). A cluster analysis is then performed to identify when different appliances are turned on and off. If a 60-watt bulb is turned on, for example, followed by a 100 watt bulb being turned on, followed by the 60 watt bulb being turned off followed by the 100 watt bulb being turned off, the NALM unit will match the on and off signals from the 60 watt bulb and the on and off signals from the 100 watt bulb to determine how much power was used by each bulb and when. The system is sufficiently sensitive that individual 60 watt bulbs can be discriminated due to the normal variations in actual power draw of bulbs with the same nominal rating. (e.g. one bulb might draw 61 watts, another 62 watts).

Figure 8 from US patent 4858141 showing how differences in reactive power can help distinguish one appliance from another

The system can measure both reactive power and real power. Hence two appliances with the same total power draw can be distinguished by differences in their complex impedance. As shown in figure 8 from the patent, for example, a refrigerator electric motor and a pure resistive heater can be distinguished in part because the electric motor has significant changes in reactive power when it turns on and off, whereas the heater has almost none.

NILM systems can also identify appliances with a series of individual changes in power draw. These appliances are modeled as finite state machines. A dishwasher, for example, has heaters and motors that turn on and off during a typical dish washing cycle. These will be identified as clusters, and power draw for the entire cluster will be recorded. Hence “dishwasher” power draw can be identified as opposed to “Resistor heating unit” and “Electric motor”.

Applications

  • NILM systems are used to perform surveys of both residential and commercial energy consumption. [1]
  • NILM algorithms have also been proposed for use in detecting drunk driving.[2]

Privacy Concerns

NILM can detect what types of appliances people have and their behavioral patterns. Patterns of energy use may indicate behavior patterns, such as routine times that nobody is at home, or embarrassing or illegal behavior of residents. It could, for example, reveal when the occupants of a house are using the shower, or when individual lights are turned on and off.[3]

If the NILM is running remotely at a utility or by a third party, the homeowner may not know that their behavior is being monitored and recorded.

A stand-alone in home system, under the control of the user, can provide feedback about energy use, without revealing information to others. Drawing links between their behavior and energy consumption may help reduce energy consumption, improve efficiency, flatten peak loads, save money, or balance appliance use with green energy availability. This form of disaggregation could be good enough to create a bill or footprint for each of your appliances automatically over a period of time. However the use of a stand-alone system does not protect one from remote monitoring.

The accuracy and capability of this technology is still developing and is not 100% reliable in near-real-time, such that complete information is accumulated and analyzed over periods ranging from minutes to hours.

See also

References

  1. ^ Christopher Laughman et al. “Advanced Nonintrusive Monitoring of Electric Loads”, IEEE Power and Energy Magazine, March/April 2003, 56 – 63.
  2. ^ Nowotarski, “SoberTeen Driving Insurance”, US patent application 20090063201 posted on Peer to Patent
  3. ^ Hart, G.W., "Residential energy monitoring and computerized surveillance via utility power flows", Technology and Society Magazine, IEEE, Jun 1989, Volume: 8, Issue: 2,pp 12–16

External links


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Energy monitoring and targeting — (M T) is an energy efficiency technique based on the standard management axiom stating that “you cannot manage what you cannot measure”. M T techniques provide Energy Managers with feedback on operating practices, results of energy management… …   Wikipedia

  • Electricity meter — Typical North American domestic analog electricity meter …   Wikipedia

  • Smart grid — Public infrastructure …   Wikipedia

  • Electrical grid — Power Grid redirects here. For the board game, see Power Grid (board game). For other uses, see Grid (disambiguation). General layout of electricity networks. Voltages and depictions of electrical lines are typical for Germany and other European… …   Wikipedia

  • Super grid — Supergrid redirects here. For other uses, see Super grid (disambiguation). One conceptual plan of a super grid linking renewable sources across North Africa, the Middle East and Europe. (DESERTEC) A super grid is a wide area transmission network… …   Wikipedia

  • Outline of energy — See also: Index of energy articles In physics, energy (from the Greek ἐνέργεια – energeia, activity, operation , from ἐνεργός – energos, active, working [1]) is a scalar physical quantity that describes the amount of work that can be performed by …   Wikipedia

  • National Interest Electric Transmission Corridor — National corridor redirects here. For National Heritage Corridors, see U.S. National Heritage Area. NIETC corridor designated for the Mid Atlantic Area by the United States Department of Energy in 2007) …   Wikipedia

  • Smart meter — [ http://www.elstermetering.com/en/1914.shtml Elster REX] ) with 900MHz [ [http://www.elster eis.com/en/LAN.html EnergyAxis LAN 900MHz Frequency hopping spread spectrum (FHSS) radio] ] mesh network topology for automatic meter reading and… …   Wikipedia

  • Rural electrification — is the process of bringing electrical power to rural and remote areas. Electricity is used not only for lighting and household purposes, but it also allows for mechanization of many farming operations, such as threshing, milking, and hoisting… …   Wikipedia

  • Automatic meter reading — [ smart meter ( [http://www.elstermetering.com/en/1914.shtml Elster REX type R15] ) with 900MHz mesh network topology for AMR] Automatic meter reading, or AMR, is the technology of automatically collecting data from water meter or energy metering …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”