Aspects of Relevance in Offshore Wind Farm Reliability Assessment Nicola Barberis Negra 2 nd PhD Seminar on Wind Energy in Europe Risø National Laboratory, 4-5 October 2006

5 th October 2006Nicola Barberis Negra - 2 Outline Introduction to Reliability Why Wind Generation into Reliability Example of Evaluation Conclusions Questions

5 th October 2006Nicola Barberis Negra - 3 Outline Introduction to Reliability Why Wind Generation into Reliability Example of Evaluation Conclusions Questions

5 th October 2006Nicola Barberis Negra - 4 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

5 th October 2006Nicola Barberis Negra - 5 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)

5 th October 2006Nicola Barberis Negra - 6 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)

5 th October 2006Nicola Barberis Negra - 7 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

5 th October 2006Nicola Barberis Negra - 8 Outline Introduction to Reliability Why Wind Generation into Reliability Example of Evaluation Conclusions Questions

5 th October 2006Nicola Barberis Negra - 9 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)

5 th October 2006Nicola Barberis Negra - 10 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

5 th October 2006Nicola Barberis Negra - 11 Outline Introduction to Reliability Why Wind Generation into Reliability Example of Evaluation Conclusions Questions

5 th October 2006Nicola Barberis Negra - 12 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

5 th October 2006Nicola Barberis Negra - 13 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

5 th October 2006Nicola Barberis Negra - 14 Example – System Definition Component data Nr.Failure rateMTTR Wind turbine (Vestas V90)251,5 1/y490 h/y Cable (~700 m)250,015 1/y/km1440 h/y Connector (~10 km)30,015 1/y/km1440 h/y Wind farm layout

5 th October 2006Nicola Barberis Negra - 15 Example – Simulation Procedure 2. Component availability 3. Wind speed time series 4. Wind Farm output power 5. Wind Farm Indices

5 th October 2006Nicola Barberis Negra - 16 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 IndexValueUnit 1. IWP75MW 2. IWE657000,00MWh 3. EAWE281657,91MWh 4. EGWEWTF260479,91MWh 5. EGWE258344,21MWh 6. CF0, GR0,9237- Simulation time10722s Result accuracy0,2% Nr of Samples485-

5 th October 2006Nicola Barberis Negra - 17 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 IndexValueUnit 1. IWP75MW 2. IWE657000,00MWh 3. EAWE281657,91MWh 4. EGWEWTF260479,91MWh 5. EGWE258344,21MWh 6. CF0, GR0,9237- Simulation time10722s Result accuracy0,2% Nr of Samples485-

5 th October 2006Nicola Barberis Negra - 18 Outline Introduction to Reliability Why Wind Generation into Reliability Example of Evaluation Conclusions Questions

5 th October 2006Nicola Barberis Negra - 19 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

5 th October 2006Nicola Barberis Negra - 20 Outline Introduction to Reliability Why Wind Generation into Reliability Example of Evaluation Conclusions Questions