Asset Performance andHealth Management in Power Generation

Stephan Heyns

University of Pretoria

stephan.heyns@up.ac.za

Centre for Asset Integrity Management (C-AIM)

• Ensure fitness-for-service

• of mechanical assets

• over entire life cycle

• while extending its remaining life

• in most reliable, safe, and cost-effective ways

C-AIM Research Domain

Lab simulations

C-AIM Staff

Academic

Prof Stephan Heyns (vibration, asset integrity management)Prof Nico Theron (controls, finite elements)Prof Schalk Kok (numerical modelling, materials)Prof Jasper Coetzee (30% maintenance)Dr Nico Wilke (optimisation, finite elements)Dr Coenie Thiart (CBM and maint. modelling)Dr Bo Xing (eMaintenance, robotics)Helen Inglis (multi-scale modelling)Francesco Pietra (finite elements, ANSYS, design)Karl Grimsehl (design)

TUT Dr Dawood Desai

Students

40 masters and 10 doctoral students

160 undergraduate project students

Research and project staff

Dr Abrie Oberholster (vibration monitoring, optical measurement)

Jan Eksteen (response reconstruction, fatigue)

Alewyn Grové (finite elements, integrity assessment, field testing)

Rudi Kroch (condition monitoring, field testing, technical acoustics)

Support Staff

George Harley (program manager)

Herman Booysen (electronics)

George Breitenbach (rotordynamics)

Johann Clarke (structural testing)

Phuti Matsaola (structural testing, strain gauges)

Jacob Madileng (structural testing)

Marietjie Calder (administrative support)

Sasol Laboratory for Structural Mechanics Asset Integrity Management

Signal Low-Pass Filter

Spectrum

Re-Sample

Band-Stop Filter Time-Frequency

Analysis

Spectrum

Specialised signal processingFatigue testing

Gearbox vibration monitoring

Turbomachine condition monitoring

Electrical machine condition monitoring Electrical

machinefinite element modelling

Rotating machine condition monitoring algorithm development and testing

• Servo-hydraulic and

• Electro-dynamic actuators durability

• Fault simulators

• Vibration transducers & analysers

• Scanning laser vibrometry

• Photogrammetry for full field strain

• Finite element analysis

• Multi-body dynamics

• Signal processing

Industry Support

• Eskom Chair in Plant Asset Management

• Chair in Maintenance Engineering• Weir Minerals Chair (Condition Monitoring)

• Rand Water Chair in Mechanical Engineering

Physical Asset Management Programme

7

• Great need for a formal multi-disciplinary post-graduate programme

focussed on Physical Asset Management in engineering environments.

• EBIT offers a broad skills base over various departments.

• This has in the past made it difficult for industry to access this

expertise.

• A multi-disciplinary programme in Physical Asset Management

introduced from 1 January 2013.

• C-AIM and the Graduate School of Technology Management (GSTM) co-leaders of the Programme

• Supported by Civil, Industrial and Mining Engineering

Critical Assets:

• Critical

• Non-critical

• Run-to-failure

• PM Templates

Design:Transformer coil response modelling

• Measure lateral vibration response of transformer coil windings due to axial loading

• FEM validation

• Modal testing

• 200kN hydraulic actuator

– Impulse excitation

• Electromagnetic excitation

Data-acquisitioning:Non-contact sensors

Development of no contact turbine blade monitoring conditions – laser vibrometry and microwave sensors

Data-acquisitioning:Non-contact sensors

(b)(a)

Shaft encoder

DIC markers

Laser measurement

location

PSV 300

GOM cameras

Test rotor

• Scanning laser vibrometry• Stereo videography

Data-acquisitioning:Online turbomachinery blade condition monitoring

• Phase based continuous microwave sensors

– MEGGITT Sensing Systems

– 200 oC

– Operation in steam environment

• Blade tip timing

Condition monitoring:Failure modes Non-destructive testing

Numerical and experimental investigations using stochastic techniques to enhance NDT info and identify high risk parts of boiler > maintenance decisions

Condition monitoring:Discrepancy Transforms

Autoregressive filters

(linear steady state)

• Parallel adaptive AR filters

• SANC technique based on LMS adaptive filter

• Schur filter

• Non-linear principal components

• Likelihood measures based on Gaussian mixture models

Models rather than data samples

Condition Monitoring:Fluctuating load/speed conditions on gearboxes

Accelerated test 17 hLocal damage shows after 8 h Pinion fails not gearMuch earlier than frequency domain

Diagnostics:Diagnostics for generator end windings• Generator end

windings:

• Finite element superelementmodelling

• Model updating using experimental modal analysis

• Detailed measurement and analysis of vibration signals

Diagnostics:Diagnostics for generator end windings

Characterization:

• Static testing

• Dynamic testing

• System testingLoad vs Displacement

0

0.001

0.002

0.003

0.004

0.005

0 200 400 600

Load (N)

Dis

pla

cem

en

t (m

)

wedge_1

wedge_2

Prognostics:Residual life modelling steam turbines

Prognostics:Measurement and analysis of turbine torsional responses

• Torsional impulse excitation of turbine via generator due to electrical grid disturbances

• Excitation of blade modes that couple with rotor torsion

• Measurement of blade vibration responses

• Indirect measurement

• Finite element modelling

Life cycle decision support:Optimum refurbishment scheduling of steam turbines

• Turbine damage mechanisms

• Risk model development

• Testing the risk model

Standards:Pump criticality

Pump criticality and maintenance strategies in power generation

Feed pumpsAsh pumps

PAS 55 ISO 55 000

Input loading:Inverse problems

Determine input loading from response measurements only

Conclusions

• Asset Integrity Management is a diverse field which require a multi-disciplinary approach which is often inconsistent with the way in which university curricula are structured

• The Centre for Asset Integrity Management is tryingto address this issue.

• There is a huge interest from industry partners, academic staff and high quality post-graduatestudents