Load measurement in rotor blades Robust sensor design
Rotor blades are subjected to extreme environmental conditions and strain. Due to the ever-increasing length of blades, growing demands are placed on monitoring. The rotor monitoring system (RM-S) from Phoenix Contact continuously monitors the stress and loads placed on the rotor blades. When the set limit values are exceeded, alarms are sent, and operators are always kept informed of the condition of the blades.
Application
The rotor blades are subject to very large dynamic forces which can lead to structural damage to the blades over the service life. Damage can be detected early by continuously monitoring loads and vibrations. This data allows optimized load-based control of wind turbine generators, which means that the stress on the blades can be reduced to a minimum. Any damage that occurs will be detected early, and can be repaired with minimal effort.
Rotor monitoring system (RM-S) The solution for load monitoring
The rotor monitoring system (RM-S) measures the loads on the rotor blades of wind turbine generators caused by bending moments. It can be used to implement predictive maintenance applications, extend plant operating time, or proactively reduce loads with a suitable closed-loop control. To do so, high-precision yet robust sensors based on strain gauges are attached to the inner side of the rotor blades of a wind turbine generator near the base of the blade.
The solution’s core elements are the specially developed strain gauges and a controller from Phoenix Contact with PLCnext architecture. The controller is connected to the sensors in the rotor blades via directly connected, high-resolution Axioline F modules. To protect the system against overvoltages and lightning strikes, suitable protective devices are installed for the sensor cables and the power supply. Optionally, a modem can be used to upgrade the system for direct, wireless communication. The system provides you with a PROFINET, Modbus/TCP, OPC-UA, or CANOpen interface.
The measured variables are received by the controller and preprocessed in order to provide you with signals with physical units. And variables derived from the strain signal, such as bending moment or the tension in the material, are calculated. In addition, statistical parameters, minimum and maximum values, signal variance values, and mean values are acquired.
Limit values can also be specified so that automatic alerts can be sent via one of the bus interfaces if limit values are exceeded.
The data processed in that way is made available simultaneously to the higher-level controller for signal scanning. All raw data can be buffered in CSV or binary format to an SD card on an sFTP server, and an independent system can fetch it from there for further analysis.
To do so, the RM-S provides you with a commissioning interface based on web technology in the form of an HMI. You do not require any software other than a browser. Using the HMI, you can set up the system, visualize the measured values, and monitor the system status.
RM-S: Robust sensor design
Sensors:
Phoenix Contact has developed special sensors that are suitable for the special conditions inside a wind turbine generator rotor blade. These sensors are built so robustly that they can be installed reliably even under adverse conditions and at the same time are well protected against external influences.
The controller acquires the signals from the connected sensors. During this quick signal processing, the measured values are filtered and checked for plausibility. Additionally, the measured values are used to determine the minimum, medium, and maximum bending moment, as well as the speed the rotor rotates at. If the set limit values are exceeded, an alarm can be set using freely programmable digital outputs. The processed data is made available simultaneously to the higher-level controller for signal scanning. Through the network, all raw data can be saved in a Microsoft SQL database or in CSV format to an SD card or an FTP server, and can be evaluated using an independent system. The RM-S also records the present load spectrum. Load spectrum mapping is used for acquiring vibration amplitudes that cause structural damage to the rotor blades over the entire service life. These values make it possible to estimate the remaining service life.
As a retrofit or for new installations
The RM-S can be integrated directly into the electrical design of the system or retrofitted in existing systems. The retrofit version consists of a fully configured control cabinet, which is built into the hub and is integrated into the controller via the existing interfaces.
Optionally, the data can be directly transmitted to the operator via the GSM modem. In the case of new installations, the required hardware, such as the controller and I/O modules, is integrated directly into the wind turbine generator’s pitch control cabinet. In this case, the software is transferred to the controller using an SD card.
Your advantages:
- Condition-based maintenance of rotor blades with early detection of damage
- Reduced strain on the blades with load-optimized closed-loop control of the wind turbine generator
- Reliable operation with robust components suitable for the conditions encountered in wind turbine generators
- Open system for optimum integration into existing systems
Your advantages
- Condition-based maintenance of rotor blades with early detection of damage
- Reduced strain on the blades with load-optimized closed-loop control of the wind turbine generator
- Reliable operation with robust components suitable for the conditions encountered in wind turbine generators
- Open system for optimum integration into existing systems
