1. Rotor Pole Temperature Sensor Network
Danu, Justin, Jay

2. Project Description Noxon, Mt
Noxon Dam, Mt is used to compensate for the power generated by wind. This along with imbalances in the air-gap of the generators leads to heating of the pole faces on the rotor.
Noxon, Mt

3. Specifications Interface to PLC: 4-20mA Accuracy of +/-5 C
Sample Rate: ~2 per minute
Self-powered
Insulation Class F: 155C max
There are many sensors to monitor the generators for preventative maintenance and reliability but there is no rotor pole temperature sensor system to measure pole temp.
The purpose of the project is to create a sensor system to measure the rotor pole temperature.
The data will be used in worst case analysis and protection of the rotor insulation.
5 Units, 4 sisters (1-4): 72 poles, unit 5: 68 poles

4. Rotor Pole Hot Spots No Damper Windings Air-gap Imbalance
Location of hot spots is likely on the pole face due to slot harmonics and air-gap imbalance.
The actual hot spot location is unknown.
Our focus is a proof of concept such that the sensor location can be determined at a later time.

5. Temperature Sensing Remote: from Stator Direct: on Rotor
Track Rotor Position
Not accurate
Direct: on Rotor
Very accurate
Sensor Options
Communication Channel
Power?
Can’t use current and voltage measurements of the field since the windings are in series. This would result in a calculation for the average temperature of the coils.

6. Block Diagram

7. Temp Sensor RTD Thermocouple
RTD: platinum temperature dependent resistor ~$55
Thermocouple: voltage output proportional to thermal gradient of different metals
IR:
Analog outputs

8. RTD
~$33
Flat Package
Fast Response
Tight Tolerances

9. Thermocouple
Easy to Customize
-50 to 200 C
2.2C Accuracy

10. Communication Wireless Magnetic Optical Zigbee Wired
Power Line Carrier
Channel requirements:
30bps per pole
2.16kpbs per rotor
One of the challenges faces by the team is getting the temperature readings of the rotor to the programmable logic controller. Originally, the team opted to use infrared technology and place a sensor on the stator. The pole temperature would be taken remotely as each pole passed by the sensor. Unfortunately, this technology already exists and Avista has a beta version installed on one unit at Noxon. The Beta version does not work well so Avista opted for a solution with the sensor mounted on the rotor. Therefore, the design must implement a communication channel. Four different technologies are under consideration.

11. Zigbee ~$20 per 250kbps 915Mhz or 2.4Ghz Digital interface
65,000 nodes

12. Optical ~$15 per channel 115kbps IR channel Digital interface
Short Range (<1m)
Rotor tracking required

13. Magnetic Custom Design
Drive, receiver, protocol, error detection/correction
Unsure of Bandwidth
Very sensitive
Short range
Rotor tracking required

14. Power Line Carrier ~$50 and up per channel 1.44kbps half duplex
Slip Ring Channel
Filter networks

15. Power Rotor Field winding Wind Magnetic field Vibration Solar Receiver
120Vac

16. Field Winding
Full load: 1200A
Series connected
~7V per pole

17. Magnetic Field
DC Field w.r.t. Rotor
Slot Harmonics
External magnets

18. Vibration Piezoelectric Resonance Low power
IEEE documents as well as datasheets show power output on the order of uW to few mW for vibrations on the order of 1m/s^2
Online documents for vibrations on rotors show accelerations on the order of 0.1m/s^2, thereforee this option does not seem like a good route

19. Wind speed ~ distance from shaft
Rotor
~100rpm rotor
30’ radius
Wind speed ~ distance from shaft
Wind
Rotor
~100rpm rotor
30’ radius
Wind speed ~ distance
from shaft

20. Solar Independent of Generator Operation Stable Output Cons Retrofit
Wiring Length

21. Power supply Design

22. Proposed Solutions Block Option 1 Option 2 Option 3 Power
Magnetic Field (slot harmonics)
Magnetic Field (permanent magnets)
Solar
Comm.
Ziqbee
Optical or Zigbee
Zigbee
Sensor
RTD

23. Option 1 Pros Communication reliability Cons Winding in air-gap Cost
Independent modules
Cons
Winding in air-gap
Cost
~$20 x2 Zigbee
~$100 RTD (3-pack)
~$25 power supply
~$25 external hardware

24. Option 2 Pros Power supply = Tracking Cons More complex comm. Cost
~same as option 1

25. Option 3 Pros Comm. Reliability Constant Power Cons Wiring Cost
~$120 more than option 1

26. Test Plan Stationary Accuracy Synchronous Generator Functionality
Need a temp probe as reference
Difficulty in testing slot harmonic magnetic field (especially on smaller machines)

27. Timeline