Condition Monitoring of Generators
ELEC-E8401 Condition Monitoring of Electrical Equipment
Minna Luojus
25.4.2016
1/8
Introduction
• Generator – one of the prime devices in a power plant
• Fixing of a generator takes a long time
•
The cost of lost production significant
• On-line continuous measurements
• Measurements and inspections during revisions
• On-line partial discharge (PD) monitoring system
25.4.2016
2/8
On-line Continuous Measurements 1/2
• Vibration Measurements
•
Several vibration measurement sensors installed
•
•
Axial and Radial x/y
Automatic controlling system
•
Permitted vibration level exceeded → alarm
•
Vibration too high → shut down command
• Temperature Measurements
•
Temperature measurement sensors
•
Temperature of generator windings is followed
25.4.2016
3/8
On-line Continuous Measurements 2/2
• Protection Relays
•
For generator and its electrical system
•
In total approx. 30 different relays
•
Generator over current, over voltage, reverse power, over frequency etc.
• Measurement of Shaft Movement
•
Generator and turbine equipped with shaft movement measurement system
•
Shaft movement affects on bearings function
25.4.2016
4/8
Condition Monitoring 1/3
• Measuring of Isolation Resistance
•
The isolation resistance of generator windings measured
•
At least once a year – usually during revision or long shut down
• Mechanical inspections
•
During generator revision, depending on the running hours of generator
•
Breaking and cracs of different mechanical constructions
•
Retaining rings, after 70 000 running hours (if old material used)
•
Stator windings slots and end-windings, after 50 000 running hours
• Tan Delta Monitoring System
25.4.2016
5/8
Condition Monitoring 2/3
- On-line Partial Discharge (PD) Monitoring System
• Continuous acquisition and analysis of electrical discharges
on an object interacted by voltage
• Early recognition of discharge phenomena
• Sensitively detects and analyses location and cause of PD
• Main components of the PD monitoring system:
•
Couplers
•
PD signal processor
•
Data acquisition and analyzing system
25.4.2016
6/8
Condition Monitoring 3/3
- On-line Partial Discharge (PD) Monitoring System
• Signals originating in the
insulation system decoupled by
the couplers
• Three dimensions used in the
processing result:
•
Phase angle  (deg)
•
Number of pulses n
•
Apparent charge q (nC)
25.4.2016
Figures: Siemens, Partial Discharge Measurement Flyer,
http://www.energy.siemens.com/br/pool/hq/services/indus
trial-applications/generators/EN-Generator-PartialDischarge-Measurement-Flyer.pdf
7/8
Conclusion
• Generator one of the main components in a power plant
→ Condition monitoring important!
• Normal on-line measuring system
•
On-line continuous measurements
• Condition monitoring system
•
Inspections and measurements during revision
•
On-line partial discharge (PD) monitoring system
25.4.2016
8/8