1. Technische Universität München
Lehrprobe - Einführung in Smart Grids
Dr. Martin Sachenbacher
Technische Universität München
Institut für Informatik
http://www.in.tum.de/energieinformatik
14. Mai 2012
M. Sachenbacher
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2. Technische Universität München
Electricity Grid Basics
Producers
Consumers
Conventional
Industry
Power Plants
Households
Pumped-
Renewable storage Plants
Energy
Storage
14. Mai 2012
M. Sachenbacher
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3. Technische Universität München
Electricity Grid Assumptions
 Guiding Principle: Production follows consumption
 Basic Assumptions:
 Production is deterministic and fully controllable
 Consumption is well-understood stochastic process
 Mass effects ensure smooth consumer behavior
 Grid state is observable (frequency, voltage)
 Thus, good prediction and a bit of fine-tuning do the job
 Control energy that be subtracted or added to the grid; mostly,
pump storage
 This was the case for several decades, but now situation
changes rapidly
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4. Technische Universität München
UK Electricity Grid Frequency
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5. Technische Universität München
Electricity Grid in Germany: Fundamental Changes
 Absolute priority given to (microgenerated) renewable power
 Financial incentives for renewable power above market price
 Decision to phase out nuclear power after Fukushima incident
14. Mai 2012
M. Sachenbacher
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6. Technische Universität München
Challenges from Integrating Renewable Power
 Wind and solar power have much higher volatility, and this
volatility is largely uncontrollable
 Production is now turning into a stochastic process as well
 Volatility may exceed the available control energy
 Need mechanisms for grid stabilization
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7. Technische Universität München
Renewable Power affects Grid Stability
 Incident on September 6, 2010
 Drastically more solar power in the grid than predicted before
 Germany at 12 p.m.: Surplus of 7 GW
 Entire negative control energy exhausted (- 4.3 GW)
 Imported emergency reserve from neighboring countries (- 2.8 GW)
to avoid black-out
 Number of manual interventions
 EWE in 2009: < 1 per week
 EWE in 2011: > 1 per day
 Bundesnetzagentur during winter 2010/11: 39
 Bundesnetzagentur during winter 2011/12: 197
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8. Technische Universität München
What can be done?
Producers
Consumers
Conventional
Industry
Power Plants
Households
Pumped-
Renewable storage Plants
Energy
Storage
14. Mai 2012
M. Sachenbacher
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9. Technische Universität München
What can be done? Storage
Source: bmvbs.de
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10. Technische Universität München
What can be done? Consumers
Source: [Wiechmann, VDE
Congress 2011]
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11. Technische Universität München
Basic Elements of Demand-Response Systems
 Short-range and medium-range prediction
techniques for
 Electric power demand
 Solar and wind generated electric power
 Grid capacity and potential grid bottlenecks
 Voltage stability, especially for last mile
 Measurement and logging infrastructure for
state of grid components
 Techniques to group elastic customers into
clusters, and orchestrate their behavior
 Decision support systems for effectuating
demand-response mechansims
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11
M. Sachenbacher

12. Technische Universität München
Decentralized Grid Management
 Frequency-based distributed control strategy (EN 50438) enforced
for microgenerators in Germany in 2007
 Must shut off the output if observed frequency overshoots 50.2 Hz
 However, observation delays can lead to critical oscillations
Source: [Berrang et al. AVACS 2012]
no delay
10s delay
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13. Technische Universität München
Decentralized Grid Management
 Improved control strategy proposed by VDE (VDE-AR-N 4105)
 Linear increase/decrease of output per minute by 10%/40%,
if frequency is observed below/above 50.2Hz
 Avoids oscillations, but may overshoot target frequency
Source: [Berrang et al. AVACS 2012]
no delay
10s delay
14. Mai 2012
M. Sachenbacher
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14. Technische Universität München
Decentralized Grid Management
 Control strategy analogous to internet transmission protocol (TCP)
proposed by [Berrang et al. 2012]
 Additive increase/multiplicative decrease of output per minute by
10%/0.67, if frequency is observed below/above 50.2Hz
 Highly dampened version of on/off-controller behavior
Source: [Berrang et al. AVACS 2012]
no delay
10s delay
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