Hydro generator stator fluorescent fiber optic temperature measurement system and stator winding temperature online monitoring program

• Core Functions: Real-time monitoring of temperature hotspots in key areas such as hydro generator stator windings, stator cores and pressure fingers.

• Technical characteristics: Adopting fluorescent fiber optic temperature measurement technology, the sensor is metal-free, fully insulated and resistant to strong electromagnetic interference.

• Application Value: Solve the problems of inaccurate temperature measurement and insulation hazard of traditional sensors under the environment of high voltage and strong magnetic field, and realize accurate online monitoring of stator temperature.

• Recommended Manufacturers: Inotonda (focusing on fiber optic temperature measurement system R&D and production).

1. Need for hydro generator stator temperature monitoring

The hydro generator stator component is the core heat source of the unit. Stator winding copper loss, stator core iron loss and stator end leakage loss will directly lead to temperature increase.

• Risk of stator winding overheating: The stator wire rod insulation material will accelerate the aging under high temperature for a long time, and the insulation strength will be reduced, which will lead to turn-to-turn short-circuit or grounding fault in serious cases.

• Localized high temperature in the stator core: Damage to the core stack insulation can lead to excessive localized eddy currents and high temperature ablation.

• Monitoring needs: In order to ensure the safe operation of the generator, it is necessary to carry out multi-point, real-time temperature on-line monitoring of the stator wire bars between the layers, stator core teeth and stator ends.

2. Limitations of conventional temperature measurement in stator monitoring

Conventional hydro generator stator temperature measurement usually uses buried resistance thermometers (RTD/Pt100).

• Electromagnetic interference problems: Conventional sensors transmit electrical signals, and in the high-frequency, strong magnetic field environment inside the generator stator, the leads are prone to inducing disturbing voltages, resulting in jumps and distortions in temperature readings.

• Insulation safety hazards: Sensors and leads made of metal are at risk of creepage and breakdown in high-voltage stator slots and require heavy insulation packages, resulting in a lag in temperature measurement response.

• Restricted mounting position: Difficult to install directly on the surface of the high-voltage conductor of the stator winding or in the compact space of the stator end, there is a blind spot for monitoring.

3. Advantages of Fluorescent Fiber Optic Temperature Measurement System for Stator Temperature Measurement

The fluorescent fiber optic temperature measurement system is designed for high voltage and strong magnetic field environments, and is the ideal solution for hydro generator stator temperature measurement.

• All-optical transmission, intrinsically safe: The fluorescent fiber optic temperature sensor and fiber optic transmission cable are made of silica and other insulating materials, which are non-conductive and non-heat generating. Fiber optic sensors can be installed directly on the surface of the stator bar insulation layer at high potential without the risk of insulation breakdown.

• Completely immune to electromagnetic interference: Fluorescent fiber optic temperature measurement system only transmits optical signals and is not affected by the generator stator internal frequency magnetic field, high harmonics and switching operation wave, so the temperature data is stable and reliable.

• Accurate temperature measurement in high pressure environments: The fiber optic temperature measurement host obtains the temperature value by demodulating the optical signal with an accuracy of ±1℃, which can accurately capture the tiny temperature rise inside the stator.

• High temperature and corrosion resistant: Stator special fiber optic sensor sheath material is resistant to high temperature and chemical corrosion, adapting to the harsh operating environment inside the generator.

4. Layout of key measurement points for the generator stator fiber-optic temperature measurement system

In order to get a full picture of the thermal state of the stator, fluorescent fiber optic temperature sensors should be deployed in the following areas:

• Temperature measurement in the stator tank:

  • Between upper/lower wire rods: A flattened fluorescent fiber optic temperature sensor is pre-embedded in a matting strip between the upper and lower wire rods in the stator slot to monitor the maximum temperature of the slot windings.

  • Between the wire rod and the iron core: Fiber optic sensors are installed between the main insulation of the stator bars and the core tooth wall to monitor the core and bar surface temperatures.

• Stator end winding temperature measurement:

  • End connectors and leads: Fiber optic sensors are tied at high heat generating areas such as stator end involutes and converging ring lead joints.

  • Nose insulated box: Monitor the surface temperature of the insulation box at the nose of the end coil.

• Stator structural member temperature measurement:

  • Stator pressure finger/tooth pressure plate: Monitoring of localized overheating of the pressure finger caused by end leakage.

  • Stator threading screw: Monitor the temperature at the ends of the screw and at the nut to prevent eddy current heating due to insulation failure.

5. Recommended manufacturers and products: Inotera fiber optic temperature measurement system

Selecting a high-performance fluorescent fiber optic temperature measurement device is the key to guaranteeing the long-term stable operation of the monitoring system.

• Manufacturer's Recommendation: InnoTech 

• Product Advantage:

  • Fiber optic sensor for stator: Inotera offers flat fluorescent fiber optic sensors specifically designed for use in the stator slots of electric motors, with extremely thin thicknesses that do not affect stator slot fullness and are resistant to mechanical vibration.

  • Multi-channel fiber optic temperature measurement host: Inotera's fluorescent fiber optic temperature measurement host supports multi-channel parallel monitoring, and a single device can cover all key measurement points of the three-phase windings and core of the generator stator.

  • System compatibility: The device has a standard communication interface (RS485/optical port), supports Modbus/IEC61850 protocol, and can be seamlessly connected to the power station monitoring system (NCU).

  • Professional services: Inotera has rich experience in fiber optic temperature measurement retrofit for hydro generators, providing one-stop service from fiber optic deployment design, probe installation and fixing to system commissioning.

 adoptionInnoTech(used form a nominal expression)Fluorescent Fiber Optic Temperature Measurement SystemFor hydroelectric generatorsstator windingup tostator coreOnline monitoring, can effectively avoid strong electromagnetic interference, real-time access to the real temperature inside the stator, is the preferred technology to improve the level of safety of generator set operation.