aspects of relevance in offshore wind farm reliability assessment nicola barberis negra...
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Aspects of Relevance in Offshore Wind Farm Reliability
Assessment
Nicola Barberis Negra
2nd PhD Seminar on Wind Energy in Europe
Risø National Laboratory, 4-5 October 2006
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Outline
• Introduction to Reliability
• Why Wind Generation into Reliability
• Example of Evaluation
• Conclusions
• Questions
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Outline
• Introduction to Reliability
• Why Wind Generation into Reliability
• Example of Evaluation
• Conclusions
• Questions
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Introduction - Definition
What is Reliability?
“Overall ability of the system to perform its function adequately, for the period of time considered, under the operation conditions intended”
Reliability in Power System
• Operation
• Planning
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Introduction – Structure of Reliability
Generating Units and Load
HLI + Transmission System
HLII + Distribution System
Generation facilities
Transmission facilities
Distribution facilities
Hierarchical Level I
(HLI)
Hierarchical Level II
(HLII)
Hierarchical Level III
(HLIII)
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Introduction – Structure of Reliability
Two new aspects
• Distributed Generation
• Private Suppliers
Generating Units and Load
HLI + Transmission System
HLII + Distribution System
Generation facilities
Transmission facilities
Distribution facilities
Hierarchical Level I
(HLI)
Hierarchical Level II
(HLII)
Hierarchical Level III
(HLIII)
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Introduction – Evaluation Methods
• Deterministic solutions
– First used approaches
– No uncertainty can be included
• Probabilistic methods
– Analytical models or simulations
– Uncertainty may be included
– Broad range of studies
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Outline
• Introduction to Reliability
• Why Wind Generation into Reliability
• Example of Evaluation
• Conclusions
• Questions
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Why Wind Energy
• New structure of power systems
– Increase of installed capacity (e.g. Germany)
– Increase of wind energy penetration (e.g. Denmark)
• Evolution of Installations
– Onshore installations (smaller and distributed)
– Offshore installations (larger and concentrated)
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Why Wind Energy - Aspects of Relevance
1. Simulation of wind speed (WS)
2. Wake effects
3. Wind turbine technology
4. Offshore environment
5. Different wind speed in the installation site
6. Power collection grid in the wind park
7. Correlation of output power for different wind farms
8. Grid connection configuration
9. Hub height variations
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Outline
• Introduction to Reliability
• Why Wind Generation into Reliability
• Example of Evaluation
• Conclusions
• Questions
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Example – Monte Carlo Simulation
“Estimation of a-posteriori reliability indices by simulating the actual random behaviour of the system for the period intended”
Main steps:
1. Simulation and system definition
2. Components availability in each sample
3. Synthetic Wind speed time series in each sample
4. Wind farm output power in each sample
5. Wind farm index evaluation
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Example – Simulation Definition
Sequential Monte Carlo simulation
• Period of 1 year with hourly step (8760 hours)
• Relevant aspects included
– Random wind speed time series
– Wind turbine technology
– Power collection grid in the wind park
– Grid connection configuration
– Offshore environment
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Example – System Definition
Component data
Nr. Failure rate MTTR
Wind turbine (Vestas V90) 25 1,5 1/y 490 h/y
Cable (~700 m) 25 0,015 1/y/km 1440 h/y
Connector (~10 km) 3 0,015 1/y/km 1440 h/y
Wind farm layout
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Example – Simulation Procedure
2. Component availability
3. Wind speed time series
4. Wind Farm output power
5. Wind Farm Indices
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Example – Results
1. IWP =Installed Wind Power
2. IWE = Installed Wind Energy
3. EAWE = Expected Available Wind Energy
4. EGWEWTF = EAWE With WT Failure
5. EGWE = Expected Generated Wind Energy
6. CF = Capacity Factor
7. GR = Generation Ratio
Index Value Unit
1. IWP 75 MW
2. IWE 657000,00 MWh
3. EAWE 281657,91 MWh
4. EGWEWTF 260479,91 MWh
5. EGWE 258344,21 MWh
6. CF 0,3932 -
7. GR 0,9237 -
Simulation time 10722 s
Result accuracy 0,2 %
Nr of Samples 485 -
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Example – Comments
• Different aspects of wind farm production
• Relevance of including component failures (indices 3 to 5)
• CF reasonable for offshore installations
• Huge computational time
• Possibility of plotting index distribution functions
Index Value Unit
1. IWP 75 MW
2. IWE 657000,00 MWh
3. EAWE 281657,91 MWh
4. EGWEWTF 260479,91 MWh
5. EGWE 258344,21 MWh
6. CF 0,3932 -
7. GR 0,9237 -
Simulation time 10722 s
Result accuracy 0,2 %
Nr of Samples 485 -
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Outline
• Introduction to Reliability
• Why Wind Generation into Reliability
• Example of Evaluation
• Conclusions
• Questions
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Conclusions
• Relevance of including wind generation into power system reliability assessment
• Importance of 9 aspects for the problem
• Monte Carlo simulation is a powerful tool, but it needs some optimizations
• Future developments
– Inclusion of all missed aspects
– Improvement of the simulation
– HLI and HLII analysis
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Outline
• Introduction to Reliability
• Why Wind Generation into Reliability
• Example of Evaluation
• Conclusions
• Questions