CN104677489A - Method for extracting vibration signal spectrum distribution characteristic parameters of transformer - Google Patents

Abstract

The invention discloses a method for extracting vibration signal spectrum distribution characteristic parameters of a transformer. The method comprises the following steps: arranging an acceleration sensor on the outer surface of a shell of the transformer, and acquiring and recording a vibration signal of the shell of the transformer by utilizing an acquisition card; performing power spectrum analysis on the vibration signal to obtain the power spectrum of the vibration signal; calculating the spectrum energy distribution percentage of the vibration signal according to the power spectrum of the vibration signal; calculating the odd-even harmonic energy ratio of the vibration signal according to the power spectrum of the vibration signal; calculating the waveform distortion ratio of the vibration signal according to the power spectrum of the vibration signal. The method has the technical effects that the spectrum distribution characteristics of the vibration signal of the transformer are quantitatively described by utilizing the spectrum energy distribution percentage, the odd-even harmonic energy ratio and the waveform distortion ratio of the vibration signal of the transformer; the loosening and the slight deformation of a winding in the transformer, and the loosening of an iron core and a fastening piece can be reflected accurately.

Description

The extracting method of transformer vibration signal spectrum distribution characteristic parameter

Technical field

The present invention designs technical field of electric equipment, is specifically a kind of extracting method of transformer vibration signal spectrum distribution characteristic parameter.

Background technology

It is ensure the reliable prerequisite of power system security that the normal table of power transformer runs.Research shows that the winding of power transformer and iron core are one of the maximum parts that break down, and due to deformation of transformer winding and core slackness, causes mechanical configuration parameter to change, transformer physical construction mechanics performance own will be caused to change.It is the effective ways evaluating Transformer Winding and iron core operation conditions and diagnosis operation troubles that vibration characteristics detects.The winding of transformer is when by load current, and between winding, will produce electric power between line cake and wire turn, winding is vibrated, and vibration frequency is 2 times of power frequencies, i.e. 100Hz.When passing through the magnetic line of force, iron core is because magnetostrictive effect is also by generation vibration, and frequency is also 100Hz.The vibration of winding and iron core is delivered to transformer oil tank wall by inside transformer securing member and insulating oil, oil tank of transformer surface is made to produce vibration, therefore by detecting the vibration signal on oil tank of transformer surface, can the physical construction situation of Real-Time Monitoring Transformer Winding and iron core.Found by research, owing to affecting by other factors such as DC magnetic biasing, also there is many high frequency harmonic components in the vibration on oil tank of transformer surface except the component of 100Hz.In vibration research before, lack the degree of depth to the spectrum analysis of vibration signal to excavate, do not extract the characteristic parameter of reflection transformer spectrum distribution directly perceived, because which limit the utilization of vibration detection method in Transformer Winding and iron core state-detection and fault diagnosis.

Summary of the invention

The object of this invention is to provide a kind of extracting method of transformer vibration signal spectrum distribution characteristic parameter, extract three characteristic parameters from the spectrum distribution of transformer vibration signal, the running status for Transformer Winding and iron core is assessed and fault diagnosis.

The technical scheme realizing the object of the invention is as follows:

An extracting method for transformer vibration signal spectrum distribution characteristic parameter, comprises

Step one: degree of will speed up sensor is arranged in transformer shell external surface, utilizes vibration signal v (t) of capture card acquisition and recording transformer shell, wherein, 0≤t≤1s, sampling rate is 25.6Ks/s;

Step 2: vibration signal v (t) is carried out power spectrumanalysis, obtains the power spectrum of vibration signal $P\left(f\right)={\∫}_{-\∞}^{+\∞}v\left(t\right)v(t+\mathrm{\τ})e^{-j2\mathrm{\πft}}\mathrm{d\τ},$ Wherein τ is offset variable, 0≤τ≤1s;

Step 3: according to power spectrum P (f) of vibration signal, asks for the spectrum energy distribution percentage of vibration signal wherein f _min=0Hz, f _max=12.8kHz, f ₁=2kHz.

Further, also comprise power spectrum P (f) according to vibration signal, ask for the odd even harmonic energy ratio of vibration signal $R_{e/o}=\frac{\underset{i=1}{\overset{\frac{f_1}{100}-1}{\mathrm{\Σ}}}{E}_i}{\underset{j=0}{\overset{\frac{f_1}{100}}{\mathrm{\Σ}}}{A}_j}$ Step, wherein, $E_i={\∫}_{i\×100-f_2}^{i\×100+f_2}P\left(f\right)\mathrm{df};A_j={\∫}_{j\×100+50-f_2}^{i\×100+50+f_2}P\left(f\right)\mathrm{df},$ f ₁＝2kHz，f ₂＝5Hz。

Further, also comprise power spectrum P (f) according to vibration signal, ask for the wave form distortion ratio of vibration signal step, wherein, A _f=P (f) | f=100, A _k=P (f) | f=100k, p _k=k, k=2,3,4....

In technique scheme, the model of described acceleration transducer is PCB356A16, and the model of described capture card is NI9234.

Technique effect of the present invention is, utilize the spectrum energy distribution percentage of transformer vibration signal, odd even harmonic energy ratio and wave form distortion than the spectrum distribution feature carrying out quantitative description transformer vibration signal, loosening and slight deformation of inside transformer winding can accurately be reflected, and the loosening of iron core and securing member.Three the transformer vibration signal spectrum signature parameters proposed according to the present invention can the running status of accurate evaluation Transformer Winding and iron core, and diagnosis transformer is in operation the fault occurred, for the safe and stable operation of transformer is given security.

Accompanying drawing explanation

The vibration signal that Fig. 1 transformer case was surveyed in 1 second;

The power spectrum of Fig. 2 transformer vibration signal;

The spectrum energy distribution percentage curve of Fig. 3 transformer vibration signal.

Embodiment

The extracting method of the transformer vibration signal spectrum distribution characteristic parameter that the present invention proposes, comprises the following steps:

(1) PCB356A16 type acceleration transducer is arranged in transformer shell external surface, NI9234 capture card is utilized to build vibrating data collection system, sampling rate 25.6Ks/s, vibration signal v (t) in acquisition and recording transformer shell 1 second, signal is as shown in Figure 1;

(2) vibration signal v (t) in transformer 1 second is carried out power spectrumanalysis, obtain power spectrum P (f) of vibration signal, it is as follows that it asks for step:

$P\left(f\right)={\∫}_{-\∞}^{+\∞}v\left(t\right)v(t+\mathrm{\τ})e^{-j2\mathrm{\πft}}\mathrm{d\τ}$

Wherein τ is offset variable, 0≤τ≤1s.

Transformer vibration signal 0Hz ~ 1000Hz power spectrum as shown in Figure 2.

(3) power spectrum P (f) of the vibration signal obtained according to step (2), try to achieve spectrum energy distribution percentage α (f) of vibration signal, it is as follows that it asks for step:

$\mathrm{\α}\left(f\right)=\frac{{\∫}_f^{f_1}P\left(f\right)\mathrm{df}}{{\∫}_{f_{\min }}^{f_{\max }}P\left(f\right)\mathrm{df}}$

Wherein f _min=0Hz, f _max=12.8kHz, f ₁=2kHz.

Transformer vibration signal 0Hz ~ 1000Hz spectrum energy distribution percentage curve as shown in Figure 3.

(4) power spectrum P (f) of the vibration signal obtained according to step (2), the odd even harmonic energy of trying to achieve vibration signal compares R _e/o, it is as follows that it asks for step:

$R_{e/o}=\frac{\underset{i=1}{\overset{\frac{f_1}{100}-1}{\mathrm{\Σ}}}{E}_i}{\underset{j=0}{\overset{\frac{f_1}{100}}{\mathrm{\Σ}}}{A}_j}$

$E_i={\∫}_{i\×100-f_2}^{i\×100+f_2}P\left(f\right)\mathrm{df};A_j={\∫}_{j\×100+50-f_2}^{i\×100+50+f_2}P\left(f\right)\mathrm{df}$

Wherein f ₁=2kHz, f ₂=5Hz.

(5) power spectrum P (f) of the vibration signal obtained according to step (2), THD is compared in the wave form distortion of trying to achieve vibration signal _weight, it is as follows that it asks for step:

${\mathrm{THD}}_{\mathrm{weight}}=\frac{1}{A_f}\sqrt{\underset{k=2}{\overset{\frac{f_1}{100}-1}{\mathrm{\Σ}}}{\left(p_k{A}_k\right)}^2}$

A _f＝P(f)|f＝100，A _k＝P(f)|f＝100k

Wherein p _k=k, k=2,3,4...

(6) with the transformer vibration signal spectrum distribution characteristic parameter that step (3), (4) and (5) obtain, state estimation and fault diagnosis are carried out to Transformer Winding and iron core.

Claims (4)

1. an extracting method for transformer vibration signal spectrum distribution characteristic parameter, is characterized in that, comprises

Step one: degree of will speed up sensor is arranged in transformer shell external surface, utilizes vibration signal v (t) of capture card acquisition and recording transformer shell, wherein, 0≤t≤1s, sampling rate is 25.6Ks/s;

Step 2: vibration signal v (t) is carried out power spectrumanalysis, obtains the power spectrum of vibration signal $P\left(f\right)={\∫}_{-\∞}^{+\∞}v\left(t\right)v(t+\mathrm{\τ})e^{-j2\mathrm{\πft}}\mathrm{d\τ},$ Wherein τ is offset variable, 0≤τ≤1s;

Step 3: according to power spectrum P (f) of vibration signal, asks for the spectrum energy distribution percentage of vibration signal wherein f _min=0Hz, f _max=12.8kHz, f ₁=2kHz.

2. the extracting method of transformer vibration signal spectrum distribution characteristic parameter as claimed in claim 1, is characterized in that, also comprise power spectrum P (f) according to vibration signal, ask for the odd even harmonic energy ratio of vibration signal step, wherein, $E_i={\∫}_{i\×100-f_2}^{i\×100+f_2}P\left(f\right)\mathrm{df};A_j={\∫}_{j\×100+50-f_2}^{i\×100+50+f_2}P\left(f\right)\mathrm{df},$ f ₁＝2kHz，f ₂＝5Hz。

3. the extracting method of transformer vibration signal spectrum distribution characteristic parameter as claimed in claim 2, is characterized in that, also comprise power spectrum P (f) according to vibration signal, ask for the wave form distortion ratio of vibration signal step, wherein, A _f=P (f) | f=100, A _k=P (f) | f=100k, p _k=k, k=2,3,4....

4. the extracting method of the transformer vibration signal spectrum distribution characteristic parameter as described in claim 1 or 2 or 3, is characterized in that, the model of described acceleration transducer is PCB356A16, and the model of described capture card is NI9234.