Post on 06-Jan-2018
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Towards Slack Analysis
Prabal Dutta and Jay Taneja
LoCal Winter RetreatJanuary 15, 2010
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Motivation: the changing energy landscape
Dispatchable Sources
Oblivious Sinks
Non-Dispatchable Sources
Aware Sinks
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Growing fraction of energy sources are renewable
• Renewables Portfolio Standard (RPS)– 36 of 50 states have set goals– Range from 10% to 25%
• California RPS– 2008: 10% (actual) – 2010: 20%– 2020: 33%
• California Mix (2008)– Biomass: 2.1%– Geothermal: 4.5%– Small Hydro: 1.4%– Solar: 0.2%– Wind: 2.4%
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Implications of “Do Nothing Well”
TX packet at 1% duty cycle (20 ms / 2 s)
4,000 ms
640,000 ms
86,400,000 ms
[Farkas00]
30 ms
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“Doing Nothing Well” on the desktop
Before installingAutoShutdownManager
After installingAutoShutdownManager
~100
x
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Over the next decade
• Sources– Increasingly non-dispatchable– Geographically distributed– Non-dispatchable loads are economically derated
• Sinks– Increasing power-proportional– Increasingly networked and intelligent– Increasing numbers of plug-in hybrid electric
vehicles
• The question: how to match supply and demand?
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The matching problem
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Outline
• Problem
• Solution Sketch
• Source Example
• Sink Example
• Other Opportunities
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What not to do: forced load shedding
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Load sculpting by squeezing, shifting, and splitting
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Towards a methodology for sculpting
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Outline
• Problem
• Solution Sketch
• Source Example
• Sink Example
• Matching Problem
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Average hourly wind speed over one year
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Average hourly wind speed over one year
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Change in average hourly wind speed
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Change in average hourly wind speed
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Probabilistic “slack” in energy production
p > 30%
p > 20%p > 20%
p < 10%p < 10%
With 90% probability, Average wind speed will change less than
±2 mph in the next hour
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Outline
• Problem
• Solution Sketch
• Source Example
• Sink Example
• Other Opportunities
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A “LoCalized” refridgerator
Switch/Meter
Energy Storage
Temp,Hum,Light
Sensors
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The life of the kitchen fridge
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Refrigerator operating cycle
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Temporal slack
Average Slack = 25 min (per 41 min cycle)Average Energy per cycle = 0.05 kWh
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Aggregating temporal slack
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Towards a measure of energy slack
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Outline
• Problem
• Solution Sketch
• Source Example
• Sink Example
• Other Opportunities
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Generalizing to the home
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Many, many open questions
• Slack metric– A single value?– A portfolio of values?– A CDF?– Formalization– Positive slack vs negative slack?
• Sculptability of other loads?
• Sculptability of other sources?
• Algorithms for dynamic demand response– Match, in real-time, sources and sinks