The profitability of a wind farm is inextricably linked to the energy output and availability of the turbines at the site. Therefore, as every wind site manager knows all too well, turbine downtime must be prevented or significantly reduced to optimize power production throughout the year.
While it’s an indisputable fact that a mechanical or environmental condition will impact the functionality of wind turbine blades at some point, there are tools and technologies to help managers plan and be more proactive about addressing potential problems before they become catastrophic.
An effective blade condition monitoring system requires robust hardware, advanced analytics and an accessible data visualization system. Such a system is essential for minimizing downtime and the associated costs in time and materials for repairs. Additionally, it provides critical data and analytics, enabling wind farm owners and managers to develop a master plan for profitability through optimized maintenance and service.
Common conditions that impact blade performance and blade life
A few conditions can negatively impact wind turbine blade performance, but they can often be identified and resolved in a timely manner by means of a comprehensive blade condition monitoring system.
Ice accumulation
Ice accumulation increases the loads on mechanical components such as rotor blades, thus negatively influencing the remaining useful lifetime of the wind turbine itself. Additionally, ice accumulation makes the blade less aerodynamic which decreases energy output of the turbine. Finally, iced blades pose a safety risk as large ice masses could break free and be thrown from the blade at high speeds, causing damage to adjacent blades, neighboring turbines, nearby structures, or even wildlife. A DNV-certified blade condition monitoring system with ice detection can mitigate those risks. The system sends a signal to the turbine controller when ice accumulation reaches a thickness threshold that is considered no longer safe to operate. Upon receiving the signal, the turbine controller can reliably stop the turbine and activate heaters to remediate the ice buildup. However, the real key to power production optimization in wintertime or in cold climates is the automatic restart of the turbine as soon as the ice has thawed to an acceptable level. With high quality blade condition monitoring, the automatic restart can be initiated as soon as the sensors detect when it’s safe to do so.
Lightning strikes
As wind turbines get larger and more powerful, the blades are getting longer. When water condensation accumulates on the blade tips, a blade is more vulnerable to damage from lightning strikes. A lightning strike can cause catastrophic damage and lead to other major component failures if the rotor is allowed to continue spinning. Some blade condition monitoring systems have a feature that detects when damage has occurred from a lightning strike and can initiate shutdown of the turbine within 5 to 10 seconds so additional damage is prevented.
Pitch angle misalignment
If the blade pitch is misaligned, this typically leads to disproportional loading and power production loss. This misalignment causes aerodynamic imbalances resulting in excessive vibration on the blades and other turbine components in the drivetrain. Avoiding premature wear through misalignment is imperative to help preserve the life of the blade.
Blade fatigue
Leading or trailing edge cracks and longitudinal cracks are related to blade fatigue. These cracks can accelerate in growth and cause major issues if not detected. In addition, wrinkles in the laminate can also influence blade fatigue. Many of these structural issues can be detected with sensors that allow the blade operator to see blade damage at an early stage without the need for physical inspection.
Blade condition monitoring facilitates effective maintenance and service
A comprehensive blade condition monitoring system might have been considered an accessory tool 10 years ago, but it is now an absolute necessity. Without real-time data, wind site managers are implementing time-based maintenance practices or simply reacting to blade issues as they occur.
Detecting cracks early on is crucial because they can quickly grow, resulting in higher repair costs or even blade replacement. Depending on the size, the cost of a new wind turbine blade can exceed $300,000, not including the cost of the crane, labor and any penalties associated with lost production. Therefore, moving to a condition-based maintenance strategy with blade monitoring is essential to manage O&M costs.
Blade maintenance is always challenging. Armed with structural health data, site managers can prioritize blade maintenance activities based on the severity of the damage. Having a monitoring system means that operating data is continuously collected and maintenance is performed based on the actual condition of the blade, which is more cost-effective as it reduces unexpected downtime.
Since planning and minimizing unplanned downtime are essential components for a wind park’s profitability, a blade condition monitoring system enables wind site owners and managers to prioritize the assets that need to be serviced and to defer noncritical repairs. It’s all about proper management of resources through a condition-based maintenance approach.
Integrated data visualization and analytics: A game-changer
A web-based graphical interface, or dashboard, shows exactly what the sensors are picking up as they monitor the vibration response of the blade. The dashboard is an insightful tool to help identify issues, create a safe and efficient maintenance strategy and facilitate better decision making to improve and streamline operations.
Stakeholders such as owners, operators or independent service providers can securely log in to see the operational state of a single turbine or the entire site. The readily available data can be viewed and analyzed from multiple perspectives and correlated with relevant turbine metadata such as rotor speed, pitch angle, output power and temperature to highlight and isolate various types of damage.
Aerial drones have been used for many years to capture external images of turbines and blades. It’s important to note that the majority of blade damage not caused by lightning strikes originates inside the blade, and internal cracks can grow quickly. These rapidly developing damages exponentially impact the cost of repairs if not detected early. Having a monitoring system that’s active 24/7 and strategically coupled to drone inspection is a cost-mindful approach to a more effective and efficient blade management program.
The bottom line: Blade condition monitoring optimizes profitability
Implementing smart technology such as blade condition monitoring with data analytics captures the onset of structural issues and aerodynamic imbalances. This insight gives wind farm managers the data they need to be more proactive and make more informed and intelligent decisions so the blades can be repaired with minimal cost and downtime. For wind site stakeholders, this solution offers a lower cost of ownership plus a better energy yield and ultimately higher profitability.
Future-forward blade condition monitoring systems are asset-agnostic and can be fit or retrofit on any brand of turbine regardless of the turbine’s age. Many wind farm managers are overseeing sites across the United States and enjoy working with a solution where one monitoring tool works on all turbines.
For all parties involved in the wind park industry, blade condition monitoring is a business case that makes sense – no matter which way the wind is blowing!
- Vibration sensors, called accelerometers, are installed inside the blade to monitor the natural frequencies and vibrations in the blade.
- An access point nacelle enables data transfer with a simple mounting via magnets.
- A hub measurement unit enables pre-treatment of data including the access point.
- Vibration sensors in each blade are installed one-third of the blade length (measuring from the root).
- An evaluation and communication unit ensures data transfer with a simple mounting via magnets to the nacelle or tower bottom.
Pete Tecos completed both his BSEE and MBA at Wayne State University. Throughout his 30+ year career, he has held a variety of executive-level roles with leading companies in the industrial automation space. He has worked in multiple industries including Automotive, Aerospace & Defense, and Energy. Currently, he is the Director of New Energy Solutions for Weidmuller USA, where his passion for Renewables is a core driver for the development of a solution portfolio.
Scott Sattler completed a BA at Bowling Green State University and a MS in Management & Organization at University of Colorado. He has been providing solutions in the wind industry since 2009 when he started selling wind tower internals, and transitioned to providing electrical components located in the nacelle. Currently, he is in Business Development for Weidmuller USA, and continues to engage with engineers and supply chain personnel to offer smart connectivity products and monitoring systems.
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