Method and apparatus for monitoring the condition of electromechanical systems

Patent metadata

Field	Value
Publication number	US-9459088-B2
Application number	US-201214115912-A
Country	US
Kind code	B2
Filing date	Mar 21, 2012
Priority date	May 12, 2011
Publication date	Oct 4, 2016
Grant date	Oct 4, 2016

Abstract

A method, apparatus and computer program for monitoring the condition of electromechanical systems in which electrical rotating machinery is used. The method includes measuring current and/or voltage signals, measuring an angular position of a rotating shaft of interest of the electromechanical systems or estimating the value of discrete angular position of a rotating shaft, synchronizing the current and/or voltage signals to the scaled angular displacement of the rotating shaft, dividing the synchronous electrical signals into intervals corresponding to each completed rotation of the rotating shaft, averaging a number of intervals of synchronous electrical signals to obtain an average synchronous electrical signal, extracting characteristic data of the magnitude from the values of the average synchronous electrical signal, and comparing the extracted characteristic data with a threshold limit to alarm the user when the limit is exceeded.

First claim

What is claimed is:

1. A method for monitoring the condition of an electromechanical system comprising the steps of:
measuring current and/or voltage signals of an electromechanical system,
measuring an angular position of a rotating shaft of interest of the electromechanical systems or estimating the value of discrete angular position of a rotating shaft of interest of the electromechanical system,
synchronizing the current and/or voltage signals to the scaled angular displacement of the rotating shaft,
dividing the synchronous electrical signals into intervals corresponding to each completed rotation of the rotating shaft,
averaging a number of intervals of synchronous electrical signals to obtain an average synchronous electrical signal, wherein the averaging of M intervals of synchronous electrical signals corresponding to M complete rotations of the rotation shaft is obtained from the average of the synchronous electrical signals ( Y ), consisting of M averaged values of the electrical signals y n which is calculated from the formula

y
_

n

=

1
M

⁢

∑

m
=
1

M

⁢

⁢

y

m
,
n

,

for
⁢

⁢
n

=
1

,
2
,
…
⁢

,
N
,

where y m,n is the synchronous electrical signal values at sampling point n in interval m, where N is a number of sampling points for every complete rotation of the rotating shaft of the electromechanical system, and where M is a number of averages to be performed,
extracting characteristic data of the magnitude from the values of the average synchronous electrical signal,
comparing the extracted characteristic data of the magnitude with a threshold which is given as a limit, and
indicating an alarm to the user when the limit is exceeded.

2. A method according to claim 1 , wherein a kurtosis S of the average synchronous electrical signals represents the characteristic data of the magnitude from the values of the average synchronous electrical signal and is calculated according to the formula:

S
=

1
N

⁢

∑

n
=
1

N

⁢

⁢

(

y
_

n

-

∑

n
=
1

N

⁢

⁢

y
_

n

)

2

.

3. An apparatus for monitoring the condition of electromechanical systems comprising:
means for measuring current and/or voltage signals of an electromechanical system,
means for measuring an angular position of a rotating shaft of interest of the electromechanical systems or means for estimating the value of discrete angular position of a rotating shaft of interest of the electromechanical system,
means for synchronizing current and/or voltage signals to a scaled angular displacement of the rotating shaft,
means for dividing the synchronous electrical signals into intervals corresponding to each completed rotation of the rotating shaft,
means for averaging a number of intervals of synchronous electrical signals, wherein the averaging of M intervals of synchronous electrical signals corresponding to M complete rotations of the rotation shaft is obtained from the average of the synchronous electrical signals ( Y ), consisting of M averaged values of the electrical signals y n which is calculated from the formula

y
_

n

=

1
M

⁢

∑

m
=
1

M

⁢

⁢

y

m
,
n

,

for
⁢

⁢
n

=
1

,
2
,
…
⁢

,
N
,

where y m,n is the synchronous electrical signal values at sampling point n in interval m, where N is a number of sampling

Assignees

• Ottewill James
• Orkisz Michal
• Abb Technology Ag

Inventors

• Ottewill James
• Orkisz Michal

Classifications

• H02P2203/05

  Determination of the rotor position by using two different methods and/or motor models · CPC title

• G01R31/2829

  Testing of circuits in sensor or actuator systems (testing of apparatus for measuring electric or magnetic variables G01R35/00; testing of indicating or recording apparatus G01D; in airbag systems B60R21/0173; checking gas analysers G01N33/007; monitoring or fail-safe circuits for electromagnets H01F7/1844) · CPC title

• H02P2203/09

  Motor speed determination based on the current and/or voltage without using a tachogenerator or a physical encoder · CPC title

• H02P2207/01

  Asynchronous machines · CPC title

• G05B19/4065

  Monitoring tool breakage, life or condition · CPC title