Advanced turbine control, yaw adjustments offer yield gains of up to 8%

A data-led performance optimization plan can boost average wind generation by between 3% and 8% and some sites can achieve further gains through forestry restructuring, Aaron Culver, Measurement & Analysis Team Leader at renewable energy consultancy SgurrEnergy, said.

Growing expertise in windfarm performance and data analytics is allowing operators to isolate and rectify specific performance issues in order to raise yield and boost project value.

Operators must access comprehensive performance data and actual wind resource information to optimize output and raise revenues, Culver told the Wind Optimization and Maintenance Canada 2016 conference on November 30, 2016.

SgurrEnergy, a Wood Group company, has assessed over 4.2 GW of wind farm capacity since 2012 on sites in the U.S., Europe and China. The performance of turbines can vary significantly, but they typically underperform expected power curves, Culver said.

"On average we see turbines underperform their power curves by about 2%," he said.

By introducing robust data collection processes and analytics and implementing regular reporting to on-site staff, firms can identify and resolve energy-clipping issues holding back production, Culver said.

Correction of static yaw misalignments can improve yields by as much as 3% with further gains possible through advanced windfarm controls and aerodynamic enhancement, and in some cases forestry restructuring, he said.

Site data

A key aspect to performance optimization is understanding actual wind conditions at the site so the performance can be analysed against available resource.

"Having numbers on availability is great, but really it's energy capture that speaks to how well your assets are performing." Culver said.

               Real average capacity factors by generation type

Source: Wind Energy Operations & Maintenance Report. Data source: EIA (2015).

Operators should attain comprehensive actual site wind data, above and below hub height, since measured levels often differ from International Electrotechnical Commission (IEC) standards at higher elevations, Culver said.

"It’s often good to have knowledge of what your wind resource is above top tip height as that is really where your resource comes from to fill in the velocity deficits," he said.

Wind shear levels can also have a significant impact on performance if outside the desired range of between -0.1 and 0.3, Culver said.

"There is underperformance of about 10% once wind shear is above 0.4," he said.

Data integrity is crucial for performance analysis, and operators should seek to analyse 10-minute SCADA data, focus on wind inflow conditions and ensure accurate event classification, Culver said.

High-frequency SCADA and load data also facilitates better decisions on uprating and lifetime extensions, he noted.

Frequent reporting

Operators must implement robust performance analytics and use SCADA trending, benchmarking, historic data and power curve analysis to inform actions, Culver said. Advanced analytics can be performed on turbine loading, control and surrounding area analysis, he said.

Key performance indicators (KPIs) should be reported to the site team on a daily or weekly basis, ideally setting out the availability, wind resource and performance relative to resource, Culver said.

"On a weekly timescale you want to tell [the site team] what's causing the most downtime and the most lost yield so they can address it in a timely manner," he said.

Reporting should present clear up to date findings on Quality Assurance and Quality Control monthly and quarterly management reviews can be held to set clear recommendations for continuous improvement, he added.

Forestry works

Some windfarm operators might consider forestry restructuring to further boost performance.

Suboptimal forestry can lead to underperformance as well as shortened component lifetimes and restructuring has proven to be beneficial for some projects in Europe, Culver noted.

In some cases, forestry restructuring could boost yields by as much as 10%, Culver said.

"Even in farmland when you have little groups of trees, that still has a substantial impact in the turbulence, wind shear and wind speed at your turbines. Forestry restructuring can boost your AEP [average energy production] but it can also decrease loads and allow for things like turbine upgrades to occur," he said.

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