UNCERTAINTY IN WIND ENERGY YIELD PREDICTIONS
(M Sc. Group Project with Sgurr Energy)
 

Home Project Team Methodology Key Findings
 

We started our project with four sources of uncertainty.

 

 

 

 

 
After looking briefly into each of these, we limited the scope of our project, working on long term predictions using MCP method, renamed as traditional MCP method and another method called it as modified MCP method. Differences in both the methods are detailed below.



In nutshell, we can say that the modified MCP method is super set of traditional MCP method. We received the wind data for four meteorological sites and we classified them on the basis of their terrain categories.
 



Here we select any two met stations to take one as the meteorological site and other as the pseudo wind farm site. We make four such pairs of sites on the basis of their terrain which are classified as either 'flat' or 'complex'.The purpose is to study the variation in correlation parameters for Measure-Correlate-Predict (MCP) method between the wind speed data of pseudo wind farm site and reference site. We have 20 years (1978~1997) wind data available for these met sites. We selected first 10 years to calculate the correlation parameters and next 10 years to calculate the energy available in proposed pseudo wind farm.





We selected the meteorological site and pesudo wind farm site and carry out linear regression analysis for those years for which Pearson-Correlation parameter is equal or greater than 0.7.We compare the energy output between conventional MCP method and modified MCP method by using the obtained linear regression parameters. In modified MCP method, the number of years are considered 5 to calculate the average correlation parameters (slope and intercept). Calculation of energy is carried by integrating the power, which is function of cube of free stream velocity, over a year.

 
Above bar graph shows that modified method predicts well in comparision to traditional MCP method. Below graph depicts variation in energy estimates for a particular pair of sites in question with respect to increasing number of years in modified MCP method.



Now wish to address one more questions. Is five year period is reasonable enough to capture the uncertainty in estimation of energy output from particular pair of site. Here is our observation. There is significant impact in the assessment of energy yield if the number of years is increased from one to three or more for collection of wind data.

We supported our work with a case study using the data from a real wind farm. It shows how the power produced from the same site can vary dramatically from year to year.