Global wind farm capacity has exceeded 600 GW. That’s more than the average electricity consumption of the whole of North America. However, not all turbines are operating as well as they could. We estimate that production could be increased by 3% with the quick resolution of performance issues, component faults and incorrect operation. That’s almost 2 billion dollars worth of green energy every year.
To track the performance issues and incorrect operation of a wind turbine requires monitoring and one solution is to use a digital twin. But how can a digital twin be used to monitor operations and what importance does wind turbine structural monitoring play in improving wind turbine performance and increasing life? Digital twins are essentially computerized companions of their physical counterparts. In the case of wind turbines, a digital programme mirrors what its physical twin is doing whilst it operates and generates energy. It captures all data from operational turbines, analyses it and provides real-time data driven insights into underlying issues which may not have been previously identified. The type of issues detected can include turbine performance, health and identifying the remaining life of an asset. As they say, the devil is in the detail.
So, how does a digital twin help to monitor the structural condition of a wind turbine? Of course, the structure consists of all sorts of components, so let’s take the blades as an example. As the blades rotate, they cause the nacelle to oscillate in sympathy with them. This oscillation runs through the drivetrain and can be seen in some SCADA signals, such as rotor speed and power output. It’s usually lost in the standard ten-minute version of this data. But with the right analysis, it can be monitored from high frequency, one second SCADA data. A spectral analysis can identify the blade-passing frequency and measure its amplitude.
A digital twin can predict what the amplitude should be in a healthy turbine. If it’s much greater in the turbine that’s being monitored, then it’s a sign that something is wrong. Most commonly, it shows that the blades have become imbalanced, causing the oscillation to increase. The root cause might be a pitch misalignment, blade damage or something else – a physical inspection is usually required to find out what’s wrong.
A blade imbalance like this usually has only a small effect on the power production of a turbine – that’s why it’s hard to detect. But it’s value shouldn’t be underestimated. A typical 2% drop in energy production from a 2 MW turbine is worth $5,000 a year. If this fault is left undetected for many years, it will really impact the long-term profit margins of a wind farm.
For example, when WindGEMINI, DNV’s online digital twin for 24/7 access to advanced wind turbine condition and performance analytics, was deployed on one customer’s wind farm, three turbines were found to be suffering from blade imbalances. The small performance loss on a fraction of the turbines reduced the total energy production of the whole farm by only 0.1%, but that was still worth between $10,000-20,000 a year. That’s a significant loss in revenue!
Learn how DNV can help wind farm owners and operators obtain data driven insights to reduce costs, extend life and maximize production.
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