Sensor Fault Diagnosis in Wind Turbines - Wind Turbine Control and Monitoring - page 259

p h ð r ð i ÞÞ Probability density function of r(i) that depends on the vector

parameter h

q Quantization error

r(i) ith sample of the residual vector

s(r(i)) Log-likelihood ratio for r(i)

t a Alarm time instant

u s,abc , u r,abc Stator and rotor three-phase voltages

v,w Process and measurement noise vectors respectively

x State vector

y Output vector

^

Stands for estimate
m As an upper index indicates measurement
abc As a lower index indicates three-phase signals
s As a lower index indicates a stator signal (voltage or current)
r As a lower index indicates a rotor signal (voltage or current)
* As an upper index indicates a reference signal within a closed loop
L ð r ð i ÞÞ Probability law of r(i)
N p Number of encoder pulses per revolution
N ð l 0 ; R Þ Normal distribution with mean l 0 and variance R
Q s Reactive power reference
R v ,R w Variance of v and w respectively
R 1 Set of k independent residual samples
S ð R 1 Þ Log-likelihood ratio for the data set R 1 , assuming a change in the
mean at time k 0
T sc Time window used for speed estimation
T s Sampling period
T g Generator torque reference
U a ; ðÞ Probability law of a uniform statistical distribution in the interval
[a,b]

K k 0 ð R 1 Þ Likelihood ratio for the data set R 1 , assuming a change in the mean

at time k 0

x Frequency

X g Generator speed

g Portion of the damaged bars of a code wheel

Angle that fulfills x s ¼ d h s

h s

d t

h Vector that parameterizes a probability density function