Wind turbine condition monitoring
With the increasing demand for wind energy, reducing operation and maintenance (O&M) costs are becoming top priorities
It is expensive to visit wind turbines for maintenance and repair because of environmental conditions, the remote location of wind farms and the height of the nacelle. In addition, wind turbine components are designed to save weight, increasing the stress-induced failure. As the demand for wind energy is growing, reducing operation and maintenance (O&M) costs as well as increasing reliability are becoming priorities. Current O&M costs prohibit faster adoption of wind energy, and slow global acceptance of wind energy. The low-cost online condition monitoring systems predict failures, forecast maintenance activities, and lower O&M costs.
Need for condition monitoringThe current trend is using larger wind turbines in remote locations, which are increasingly offshore, for optimal wind conditions. Both the size and location factors have led to maintenance challenges which are unique compared to traditional power generation systems:
No walk-around maintenance: Unlike other power generation equipment, walk-around maintenance isn’t feasible because reaching wind turbine is difficult and expensive.
High-maintenance costs: Maintenance costs are high because of need for an expensive large crane to lift needed parts to the nacelle.
Higher propensity for failure: Gearboxes and related mechanical components are designed to save weight, leaning toward a higher probability of stress-induced failure.
High-mechanical stress: Constantly changing loads and variable operating conditions create high-mechanical stress on wind turbines, and the high degree of stress demands a high degree of maintenance.
The wind energy industry uses a reactive maintenance approach or run-to-failure maintenance which is the most costly operation and maintenance (O&M) practice.
All of these factors raise O&M cost, which affects the cost of energy (COE) metric, used for evaluating the project feasibility and return on investment.
National Instruments on condition monitoring solutionsNational Instruments provides hardware and software to design a high-performance, low-cost solution for monitoring wind turbines and wind turbine components to generator/gearbox manufacturers and wind turbine integrators. NI focuses on providing the newest, industry-proven signal processing algorithms for extracting the key features of a signal to predict the health of machine components. These algorithms include order analysis, cepstral analysis, bearing modulation detection, wavelets, AR modeling, power quality, power factor, rainfall stress cycle analysis, and statistical analysis algorithms. With NI LabVIEW software, one can use these built-in signal processing algorithms, import text codes (such as C and other math scripts), and easily design unique, evolutionary algorithms.
For example: studies show that gearbox and gearbox bearings are among the most common failure points of wind turbines. Gearbox and bearing vibration analysis using accelerometers is accepted to monitor and predict bearing and gearbox failures. However, the multitude of vibration sources in a multistage wind turbine gearbox cause a complex array of gear mesh, modulation, and running speed vibrations.
Correct analysis of gearbox vibrations requires a high-resolution spectrum analyser. This involves a wide-bandwidth vibration signal sampling instrument capable of recording a long waveform. In other words, the condition monitoring solution must have sample rates of 51.2 kHz or better and the ability to store records exceeding 2 MB of binary time waveform. The NI CompactRIO platform offers these capabilities. Advanced spectral analysis-including zoom FFT and zoom order spectrum-further clarifies high-frequency vibration characteristics without losing sideband data. Sideband analysis helps the vibration analyst determine faulty meshing gears.
These open, flexible NI LabVIEW and CompactRIO have the following benefits:
Lower cost: NI focuses on low-cost, powerful technologies for the advantage and consumption of service suppliers, wind turbine integrators, and OEMs.
Custom solutions: NI helps developers design monitoring solutions, better than the traditional condition monitoring solutions.
OEM focused: NI works with more than 900 partner developers to provide custom, ready-to-run solutions at reduced costs.
Integration of control and monitoring: NI platform can control and monitor on one platform for advanced-model based control and monitoring feedback.
Control system integration and communication protocol supportOne of the big differences with system-based NI technologies as compared to other products — besides lower-cost signal processing — is the integration capabilities of the control system. The NI platforms can communicate with onboard Ethernet, RS232 and RS485, Modbus, OPC, CAN, Fieldbus, PROFIBUS, or even proprietary communications protocols. This flexibility enables the NI system to integrate easily with other devices in the wind turbine nacelle.
NI products for condition monitoringNational Instruments offers a range of signal conditioning equipment to interface with vibration, strain, acoustics, temperature, and electricity, to name a few. Using standard communications protocols, oil particulate counts and fiber-optic sensing can add to the condition monitoring device. Its mixed-measurement capability makes National Instruments one of the leaders in condition monitoring.
