Systems and methods for monitoring surge conditions

Patent metadata

Field	Value
Publication number	US-10317276-B2
Application number	US-201414514117-A
Country	US
Kind code	B2
Filing date	Oct 14, 2014
Priority date	Oct 14, 2014
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A method for monitoring for a surge condition includes detecting a surge condition through vibration signals measured at at least one location in a turbomachine. Detecting a surge condition includes determining a ratio-metric indicator R BR by comparing a blade frequency band Ω B to a reference frequency band Ω R . Detecting a surge condition includes calculating a surge score SS with the following equation:
SS = R BR - R μ R σ
wherein R μ is a sample mean of a set of ratio-metric indicators and R σ is a sample standard deviation of a set of ratio-metric indicators. Detecting a surge condition includes determining whether a surge condition exists based on the surge score.

First claim

What is claimed is:

1. A method for monitoring for a turbomachine for a surge condition, comprising:
detecting a surge condition through vibration signals measured at at least one location in a turbomachine, wherein detecting a surge condition includes:
determining a ratio-metric indicator, R BR , by comparing a blade frequency band, Ω B , to a reference frequency band, Ω R , wherein determining the ratio-metric indicator R BR includes:
determining a time window length for vibration data acquisition;
identifying the blade frequency band Ω B and the reference frequency band Ω R ;
collecting vibration data with a known sampling rate with at least one accelerometer operable to generate the vibration signals representative of blade vibration and other vibration sources;
segmenting the vibration data into slices based on a time window;
determining a power spectrum of a given slice of vibration data;
obtaining respective residual spectrums from the power spectrum for the blade frequency band Ω B and the reference frequency band Ω R ; and
calculating the ratio-metric indicator, R BR , for the given slice of vibration data by comparing the power spectrum of the blade frequency band Ω B and the reference frequency band Ω R with the following equation:

R
BR

=

∑

ω
⋐

Ω
B

⁢



S
⁡

(
ω
)



2

∑

ω
⋐

Ω
R

⁢



S
⁡

(
ω
)



2

wherein S(ω) is the Discrete Fourier Transform, DFT, for a frequency, ω, of the given slice of vibration data;
calculating a surge score, SS, with the following equation:

SS
=

R
BR

-

R
μ

R
σ

wherein R μ is a sample mean of a set of ratio-metric indicators and R σ is a sample standard deviation of a set of ratio-metric indicators;
determining whether a surge condition exists based on the surge score SS; and
altering operation of the turbomachine if a surge condition is determined.

2. A method as recited in claim 1 , wherein determining whether a surge condition exists includes statistically analyzing populations of surge scores accumulated in different durations to monitor long term changes and drift.

3. A method as recited in claim 1 , wherein determining if a surge condition exists includes determining that the surge condition does exist if the ratio-metric indicator, R BR , deviates from the sample ratio mean, R μ , more than three times the ratio sample ratio standard deviation, R σ .

4. A method as recited in claim 1 , wherein determining whether a surge condition exists includes estimating the sample ratio mean, R μ , and the sample ratio standard deviation, R σ , from vibration signals obtained in-service as an in-system calibration process.

5. A method as recited in claim 1 , wherein determining the sample ratio mean, R μ , and the sample ratio standard deviation, R σ , includes determining ratio-metric indicator data for different speeds within an operating range under known normal conditions, collecting the ratio-metric indicator data, and calculating the sample ratio mean, R μ , and the sample ratio standard deviation, R σ , based on the collected ratio-metric indicator data.

6. A method as recited in claim 1 , wherein determining the ratio-metric indicator includes determining a respective fan rotation speed from the power spectrum.

7. A method as recited in claim 6 , wherein the step of determining the fan rotation speed includes rejecting data from which the fan rotation speed is considered to be uncertain.

8. A method as recited in claim 6 , wherein obtaining respective residual spectrums from the power spectrum includes removing peaks associated with the respective fan rotation speed and its harmonics in the blade frequency band Ω B and the reference frequency band Ω R .

9. A method as recited in claim 8 , wherein a width of a frequency window for the peaks to be removed is tied to the type of time window being used.

10. A turbomachinery surge monitoring system, comprising:
at least one sensor coupled to a compressor system; and
a processing unit coupled to the at least one sensor including a plurality of program instructions comprising:
program instructions to detect a surge condition through vibration signals measured at at least one location in a turbomachine, wherein program instructions to detect a surge condition include:
program instructions to determine a ratio-metric indicator, R BR , by comparing a blade frequency band, Ω B , to a reference frequency band, Ω R , wherein determining the ratio-metric indicator R BR includes:
determining a time window length for vibration data acquisition;
identifying the blade frequency band Ω B and the reference frequency band Ω R ;
collecting vibration data with a known sampling rate with the at least one sensor operable to generate the vibration signals representative of blade vibration and other vibration sources;
segmenting the vibration data into slices based on a time window;
determining a power spectrum of a given slice of vibration data;
obtaining respective residual spectrums from the power spectrum for the blade frequency band Ω B , and the reference frequency band Ω R ; and
calculating the ratio-metric indicator, R BR , for the given slice of vibration data by comparing the power spectrum of the blade frequency band Ω B and the reference frequency band Ω R with the following equation:

R
BR

=

∑

ω
⋐

Ω
B

Assignees

• Simmonds Precision Products

Inventors

• Liu Lei

Classifications

• F05D2270/101

  Compressor surge or stall · CPC title

• F04D29/668

  damping or preventing mechanical vibrations · CPC title

• F05D2270/334

  Vibration measurements · CPC title

• F01D21/003

  Arrangements for testing or measuring (for measuring vibrations G01H) · CPC title

• F04D27/001

  Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring · CPC title