CN103412228A - Method for measuring frequency response of distributed transformer - Google Patents

Abstract

The invention relates to a method for measuring deformation frequency response of a power transformer winding, in particular to a method for measuring frequency response of a distributed transformer. The method is characterized in that input signals are digitized at a signal injection end of a transformer winding, output signals are digitized at a signal response end of the transformer winding, and the digitized input signals and the digitized output signals are collected through a wireless network to carry out calculation to obtain the frequency response of the transformer. The problem of signal to noise ratio can be solved thoroughly by adopting a distributed digitized signal processing method. Meanwhile, due to the fact that intelligent terminals are adopted at the signal injection end and the signal output end respectively to achieve digitization and signals are transmitted wirelessly, the influences on test data by grounding distribution parameters and cable distribution parameters can be overcome.

Description

A kind of Frequency Response Test Method of distribution transformer

Technical field

The present invention relates to a kind of winding deformation of power transformer frequency response method of testing.

Background technology

Since from power industry standard DL/T911-2004 " winding deformation of power transformer frequency response analysis ", promulgating, spent the time of 10 years nearly, through application, summary for many years, suitable lifting has been arranged in the processing of method of testing and test data.Due to the very wide 1kHz-2MHz that is generally of frequency response method of testing test frequency, particularly due to the impact of ground connection and distribution parameter, be easy to cause the error of test result.At this, a kind of distributed deformation of transformer winding method of testing is proposed.

One, test philosophy:

Under the voltage effect of upper frequency, each winding of transformer all can be considered a passive linear two-port network consisted of distribution parameters such as linear resistance, inductance (mutual inductance), electric capacity, its bulk properties can be passed through transfer function H (j ω) description, as shown in Figure 1.If winding deforms, the parameters such as the distributed inductance of winding inside, electric capacity must change, and cause the zeros and poles of its equivalent network transfer function H (j ω) to change, and the frequency response characteristic of network is changed.

With frequency response analysis, detect deformation of transformer winding, be by detecting the amplitude-frequency response characteristic of each winding of transformer, and testing result is carried out to vertical or horizontal comparison, according to the difference of amplitude-frequency response characteristic, the contingent winding deformation of judgement transformer.

The amplitude-frequency response characteristic of Transformer Winding adopts frequency sweeping mode shown in Figure 1 to obtain.Continuously change the outer frequency f (angular frequency=2 π f) of executing sine-wave excitation source Vs, the ratio of the signal amplitude of the responder voltage V2 of measurement under different frequency and excitation terminal voltage V1, obtain the amplitude-frequency response of specifying winding in excitation end and responder situation.In Fig. 1: L, K and C represent that respectively the distributed inductance of winding unit length, distributed capacitance reach distributed capacitance over the ground, V1, V2 are respectively excitation terminal voltage and the responder voltage of equivalent network, Vs is sine wave exciting signal source voltage, and Rs is signal source output impedance, and R is build-out resistor.

In sum, traditional winding deformation of power transformer frequency response method of testing is normally moved the signal of transformer on ground to and is tested, and there are two technical matterss usually in such test:

One: because frequency response signal is little, frequency is high, originally test cable is grown (20 meters left and right), and signal is easy to be disturbed;

As shown in Figure 2, its two: system has more distribution parameter, and distribution parameter exists unstable and changes larger characteristics, and the result of frequency sound test is had a certain impact.

Summary of the invention

The object of the invention is to overcome existing above-mentioned deficiency in prior art, a kind of Frequency Response Test Method of distribution transformer is provided, to thorough solution one, signal to noise ratio (S/N ratio) problem; Two, solve the impact on test data of ground connection distribution parameter and cable distribution parameter.In order to realize the foregoing invention purpose, the invention provides following technical scheme:

A kind of Frequency Response Test Method of distribution transformer, at the signal injection end of Transformer Winding by the input signal digitizing; At the signal response end of Transformer Winding by the output signal digitizing; By wireless network, digitized input signal and output signal are collected and calculate the Frequency Response of transformer.

The Frequency Response Test Method of described a kind of distribution transformer is specifically:

The first step: system software is sent out the output drive signal by the controlled in wireless end of main control unit to the first test cell, the first test cell response, and the output drive signal, and be loaded on described Transformer Winding;

Second step: software sends the startup test signal by the controlled in wireless end of main control unit to the first test cell and the second test cell;

The 3rd step: the first test cell and the second test cell are made response to test signal, synchronous acquisition, the analog to digital conversion of settling signal save data; The 4th step: software is collected the test signal of the first test cell and the second test cell in PC software by the controlled in wireless end of main control unit, calculates, processes, and obtains the frequency response of transformer.

Described main control unit is that notebook computer is controlled by USB, and as shown in Figure 4, the program circuit of main control unit is as follows:

The first step: power up startup;

Second step: initiating hardware;

The 3rd step: wait for the PC instruction;

The 4th step: if instruction is arranged, analysis instruction, response instruction, if do not have, wait for the PC instruction;

The 5th step: if two test cell responses are normal, send the signal output order to the first test cell; If undesired return to the 3rd step;

The 6th step: send out test starting command to two test cells, until last measurement point is completed to measurement.

The first test cell, the second test cell all receive only the wireless control signal from main control unit, and responsing control command, and as shown in Figure 5, the program circuit of the first test cell, the second test cell is as follows:

The first step: power up startup;

Second step: initiating hardware;

The 3rd step: wait for the main control unit instruction;

The 4th step: if instruction is arranged, response instruction, if do not have, return to the 3rd step.

Described software is collected the test signal of two unit in PC software by the controlled in wireless end of main control unit, calculates, processes.

Described " software " belongs to as well known to those skilled in the art, does not do and repeats at this.

The image data length of supposing the first test cell and the second test cell is N, and corresponding data queue is X (k), Y (k), k=0,1 ..., N-1, and X (k), Y (k) are real number, as follows for the computing formula of the coefficient R of winding deformation judgement.

A.1 calculate the standard variance of two sequences

$\mathrm{Dx}=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[X\left(k\right)-\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}X\left(k\right){]}^2$ $\mathrm{Dy}=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[Y\left(k\right)-\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}Y\left(k\right){]}^2$

A.2 calculate the covariance of two sequences

$C_{\mathrm{xy}}=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[X\left(k\right)-\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}X\left(k\right)]\×[Y\left(k\right)-\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}Y\left(k\right)]$

A.3 calculate the normalized covariance coefficient of two sequences

${\mathrm{LR}}_{\mathrm{xy}}=\mathrm{Cxy}/\sqrt{\mathrm{DxDy}}$

A.4 according to following formula, calculate the coefficient R that meets requirement of engineering _Xy

The Hz-KHz of the Frequency Response Test Method of described a kind of distribution transformer is that 10Hz is to 10MHz.

The Hz-KHz of the Frequency Response Test Method of described a kind of distribution transformer is that 1KHz is to 2MHz.

Compared with prior art, beneficial effect of the present invention:

One and adopt the distributed digital signal processing method, can thoroughly solve the signal to noise ratio (S/N ratio) problem.

Two, adopt the disposal route of distributed digital, namely at signal injection end and output terminal, adopt respectively intelligent terminal, complete digitizing and, by wireless transmission, can solve the impact on test data of ground connection distribution parameter and cable distribution parameter.

The accompanying drawing explanation:

Fig. 1 is deformation of transformer winding test schematic diagram;

Fig. 2 is system distribution parameter schematic diagram;

Fig. 3 is distributed signal disposal system structural drawing;

Fig. 4 is the program flow diagram of main control unit;

Fig. 5 is the program flow diagram of the first test cell and the second test cell.

Embodiment

The present invention is described in further detail below in conjunction with test example and embodiment.But this should be interpreted as to the scope of the above-mentioned theme of the present invention only limits to following embodiment, all technology realized based on content of the present invention all belong to scope of the present invention.

A kind of Frequency Response Test Method of distribution transformer, at the signal injection end of Transformer Winding by the input signal digitizing; At the signal response end of Transformer Winding by the output signal digitizing; By wireless network, digitized input signal and output signal are collected and calculate the Frequency Response of Transformer Winding.

The Frequency Response Test Method of described a kind of distribution transformer is specifically:

The first step: system software is sent out the output drive signal by the controlled in wireless end of main control unit to the first test cell, the first test cell response, and the output drive signal, and be loaded on described Transformer Winding;

Second step: software sends the startup test signal by the controlled in wireless end of main control unit to the first test cell and the second test cell;

The 3rd step: the first test cell and the second test cell are made response to test signal, synchronous acquisition, the analog to digital conversion of settling signal save data; The 4th step: software is collected the test signal of the first test cell and the second test cell in PC software by the controlled in wireless end of main control unit, calculates, processes, and obtains the Frequency Response of Transformer Winding.

Fig. 3 is distributed signal disposal system structural drawing.

Described main control unit is that notebook computer is controlled by USB, and as shown in Figure 4, the program circuit of main control unit is as follows:

The first step: power up startup;

Second step: initiating hardware;

The 3rd step: wait for the PC instruction;

The 4th step: if instruction is arranged, analysis instruction, response instruction, if do not have, wait for the PC instruction;

The 5th step: if two test cell responses are normal, send the signal output order to the first test cell; If undesired return to the 3rd step;

The 6th step: send out test starting command to two test cells, until last measurement point is completed to measurement.

The first test cell, the second test cell all receive only the wireless control signal from main control unit, and responsing control command, and as shown in Figure 5, the program circuit of the first test cell, the second test cell is as follows:

The first step: power up startup;

Second step: initiating hardware;

The 3rd step: wait for the main control unit instruction;

The 4th step: if instruction is arranged, response instruction, if do not have, return to the 3rd step.

Described software is collected the test signal of two unit in PC software by the controlled in wireless end of main control unit, calculates, processes.

Described " software " belongs to as well known to those skilled in the art, does not do and repeats at this.

The image data length of supposing the first test cell and the second test cell is N, and corresponding data queue is X (k), Y (k), k=0,1 ..., N-1, and X (k), Y (k) are real number, as follows for the computing formula of the coefficient R of winding deformation judgement.

A.1 calculate the standard variance of two sequences

$\mathrm{Dx}=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[X\left(k\right)-\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}X\left(k\right){]}^2$ $\mathrm{Dy}=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[Y\left(k\right)-\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}Y\left(k\right){]}^2$

A.2 calculate the covariance of two sequences

$C_{\mathrm{xy}}=\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}[X\left(k\right)-\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}X\left(k\right)]\×[Y\left(k\right)-\frac{1}{N}\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}Y\left(k\right)]$

A.3 calculate the normalized covariance coefficient of two sequences

${\mathrm{LR}}_{\mathrm{xy}}=\mathrm{Cxy}/\sqrt{\mathrm{DxDy}}$

A.4 according to following formula, calculate the coefficient R that meets requirement of engineering _Xy

The Hz-KHz of the Frequency Response Test Method of described a kind of distribution transformer is that 10Hz is to 10MHz.

The Hz-KHz of the Frequency Response Test Method of described a kind of distribution transformer is that 1KHz is to 2MHz.

Claims (4)

1. the Frequency Response Test Method of a distribution transformer, is characterized in that, at the signal injection end of Transformer Winding by the input signal digitizing; At the signal response end of Transformer Winding by the output signal digitizing; By wireless network, digitized input signal and output signal are collected and calculate the Frequency Response of Transformer Winding.

2. the Frequency Response Test Method of a kind of distribution transformer winding as claimed in claim 1, Frequency Response Test Method be specifically:

The first step: system software is sent out the output drive signal by the controlled in wireless end of main control unit to the first test cell, the first test cell response, and the output drive signal, and be loaded on described Transformer Winding;

Second step: software sends the startup test signal by the controlled in wireless end of main control unit to the first test cell and the second test cell;

The 3rd step: the first test cell and the second test cell are made response to test signal, synchronous acquisition, the analog to digital conversion of settling signal save data;

The 4th step: software is collected the test signal of the first test cell and the second test cell in PC software by the controlled in wireless end of main control unit, calculates, processes, and obtains the frequency response of transformer.

3. the Frequency Response Test Method of a kind of distribution transformer winding as claimed in claim 1 or 2, is characterized in that, the Hz-KHz of the Frequency Response Test Method of described a kind of distribution transformer is that 10Hz is to 10MHz.

4. the Frequency Response Test Method of a kind of distribution transformer as claimed in claim 1 or 2, is characterized in that, the Hz-KHz of the Frequency Response Test Method of described a kind of distribution transformer is that 1KHz is to 2MHz.

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