Title: Condition monitoring artefacts for detecting winding faults in wind turbine DFIGs
1Condition monitoring artefacts for detecting
winding faults in wind turbine DFIGs
By
(1) School of Electrical and Electronic
Engineering, The University of Manchester
(2) School of Engineering, Durham University
2Introduction
- Doubly fed induction generator (DFIG) is the most
commonly used type of generator in contemporary
large variable speed wind turbines - One of the most common induction machine faults
are winding faults due to short-circuit or
open-circuit or abnormal connection of phase
windings - A common fault diagnostic method is the
investigation of frequency spectrum content of
machine steady state electrical quantities such
as current and instantaneous power - non invasive
as stator windings are used as search coils.
3DFIG modelling for condition monitoring purposes
- Based on coupled-circuit approach
- A circuit is defined as any series connection of
coils - Coupling inductances are calculated between
circuits - This approach makes it possible to analyze an
arbitrarily connected n-phase machine while
taking into account higher order field space
harmonics
4DFIG test rig diagram
5 Test Rig Description
Laboratory test bed (viewed from above)
6 Test Rig Description
DFIG Terminal box
Rotor back-to-back converter
7Healthy and faulty DFIG winding configurations
used in this presentation
a) Healthy
b) Open-circuit DFIG stator
winding configuration
8Frequency content of predicted DFIG stator line
current for healthy and faulty DFIG operation
a) Predicted current spectrum for DFIG operating
with healthy windings
b) Predicted current spectrum for DFIG operating
with faulty stator windings
9Frequency content of predicted DFIG total stator
instantaneous power for healthy and faulty DFIG
operation
a) Predicted power spectrum for DFIG operating
with healthy windings
b) Predicted power spectrum for DFIG operating
with faulty stator windings
10Predicted and measured DFIG stator line current
spectra for DFIG operation with stator
open-circuit fault
a) Experimental current spectrum
b) Predicted current spectrum
11Predicted and measured DFIG stator instantaneous
power spectra for DFIG operation with stator
open-circuit fault
a) Experimental power spectrum
b) Predicted power spectrum
12Conclusions
- A DFIG analytical model was developed and a DFIG
test rig built for the purpose of this study - Research demonstrates that there are harmonic
components in DFIG steady state stator current
and total power spectra that are directly related
to existence of winding fault. These frequencies
are slip dependant. - Simulation data indicate that the power signal
spectrum carries more fault specific information
when compared to the current signal. Measurement
of the power spectrum is however shown to be
influenced by high noise levels.
13Thank You