JP7310250B2 - Measuring device and its measuring method - Google Patents

Description

The present invention relates to a measuring device and its measuring method.

For example, a method using frequency response analysis is known as a method of diagnosing abnormalities in the windings and cores of a power transformer, which is one type of electrical equipment.

In the above method, the output signal (e.g. current ), the transfer function (e.g., impedance) corresponding to each measurement frequency is calculated, and then compared with a previously prepared transfer function that indicates that the power transformer is healthy. is a method of diagnosing whether or not is healthy (see Patent Document 1, for example).

JP 2011-253885 A

In an electric power system, since auxiliary equipment (electrical equipment) with capacitance components such as instrument transformers and surge absorbers are connected to power transformers via wiring, Since the frequency response analysis including the auxiliary equipment is performed at once, it is impossible to accurately diagnose whether the power transformer is sound by itself. Therefore, when performing a frequency response analysis of a power transformer, disconnect the wiring between the power transformer and its auxiliary equipment so that it can be diagnosed whether or not the power transformer is sound on its own. ing. However, since the wiring between the power transformer and the attached equipment has to be removed, there is a possibility that the power outage work time for the frequency response analysis will be long.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a measuring apparatus and a measuring method thereof capable of shortening the power failure work time for frequency response analysis.

The main aspect of the present invention for solving the above-described problems is that when the frequency of a sine wave signal input to a first electrical device is changed from a first measurement frequency to a second measurement frequency higher than the first measurement frequency, the A frequency response waveform generation device corresponds to each measurement frequency from the first measurement frequency to the second measurement frequency based on the output signal output from the first electrical device according to the frequency change of the sine wave signal. and inputting the sine wave signal to the first electrical device and outputting the sine wave signal from the first electrical device so as to generate a frequency response waveform of the first electrical device from the transfer function. A measurement device used to input an output signal to the frequency response waveform generator, wherein the capacitance is configured to form a resonant circuit with a capacitance component of a second electrical device connected to the first electrical device. a variable inductor connected in parallel to the component; an ammeter for measuring the current flowing through the resonant circuit; and a controller for controlling the value of the variable inductor so that the value of the current measured by the ammeter becomes zero.

Other features of the present invention will become apparent from the accompanying drawings and the description herein.

According to the present invention, it is possible to shorten the power failure work time for frequency response analysis.

It is a circuit block diagram showing an example of a measuring device concerning this embodiment. It is a block diagram showing an example of a frequency response waveform generating device in which the measuring device according to the present embodiment is used. It is a flow chart which shows an example of operation of a measuring device concerning this embodiment. It is a circuit block diagram showing another example of the measuring device according to the present embodiment.

At least the following matters will become apparent from the description of the present specification and the accompanying drawings.

===Measuring device===
FIG. 1 is a circuit block diagram showing an example of a measuring device according to this embodiment. In the present embodiment, the measuring device is connected to a permanent or mobile power transformer (first electrical device) for supplying power whose voltage has been stepped down in the distribution system to the customer. It is assumed that attached equipment (second electrical equipment) having a capacitance component such as a voltage transformer and a surge absorber is connected to the transformer via wiring.

The measuring device 100 converts the sine wave signal into power while changing the frequency of the sine wave signal over a wide range so that the frequency response waveform generating device 200 can generate a frequency response waveform for the power transformer 300 alone. It is a device that inputs to the power transformer 300 and inputs to the frequency response waveform generator 200 an output signal that is output from the power transformer 300 according to the frequency change of the sine wave signal.

The measurement device 100 includes an input voltage generator 110, a resistor 120, AC circuit voltmeters 130 and 140, a switch 150, a variable inductor 160, a control device 170, an AC circuit It is configured including an ammeter 190 .

The input voltage generator 110 is a generator that generates an input voltage Vin(jω) (sine wave signal), and changes the frequency of the input voltage Vin(jω) from a first measurement frequency (for example, several tens of Hz) to a second measurement frequency. It has a sweep function that changes up to a frequency (for example, several MHz). A resistor 120 is connected in series with the input voltage generator 110 and its resistance value is set to 50Ω, for example. A series connection of input voltage generator 110 and resistor 120 is connected in parallel to secondary winding 320 of power transformer 300 . The voltmeter 130 is connected in parallel to the input voltage generator 110 and measures the input voltage Vin(jω) whose frequency continuously changes from the first measurement frequency to the second measurement frequency. The voltmeter 140 is connected in parallel with the resistor 120 and measures the output voltage Vout(jω) (output signal) across the resistor 120 when the input voltage Vin(jω) is supplied to the secondary winding 320. to measure Note that j represents an imaginary unit, and ω represents an angular frequency.

Switch 150 is connected in parallel with primary winding 310 of power transformer 300 . When diagnosing an abnormality in the windings of the power transformer 300, the input voltage Vin(jω) and the output voltage Vout(jω) are measured with the switch 150 closed and the primary winding 310 short-circuited. On the other hand, when diagnosing an abnormality in the iron core of the power transformer 300, the input voltage Vin(jω) and the output voltage Vout(jω) are measured with the switch 150 opened and the primary winding 310 opened.

Capacitance component 500 included in the accessory is equivalent to being connected in parallel to secondary winding 320 . Therefore, variable inductor 160 is connected in parallel with capacitance component 500 so as to form resonant circuit 400 with capacitance component 500 .

The control device 170 adjusts the frequency of the input voltage Vin(jω) so that the resonance circuit 400 is always in parallel resonance while the frequency of the input voltage Vin(jω) changes from the first measurement frequency to the second measurement frequency. It is a device that adjusts the value of the variable inductor 160 according to changes.

The control device 170 includes a control section 170A and an actuator 170B as means for realizing the above functions. The functions of the control section 170A are implemented by software processing of a microcomputer.

Here, the current I _L flowing through the variable inductor 160 is represented by the following equation (1), where L is the inductance value of the variable inductor 160 and E is the voltage appearing in the secondary winding 320 .

又、キャパシタンス成分５００を流れる電流Ｉ_Ｃは、キャパシタンス成分５００のキャパシタンス値をＣとすると、以下の式（２）で表される。

Also, the current I _C flowing through the capacitance component 500 is expressed by the following equation (2), where C is the capacitance value of the capacitance component 500 .

ここで、“ωＬ＝１／ωＣ”を満足するインダクタンス値Ｌを選択すると、“Ｉ_Ｌ＝－Ｉ_Ｃ”となるため、計測装置１００から共振回路４００へ電流が流れなくなって、共振回路４００は並列共振する。このとき、計測装置１００と共振回路４００との間には無限大のインピーダンスが存在することとなるため、キャパシタンス成分５００が２次巻線３２０に接続された状態であっても、電力用変圧器３００単体としての出力電圧Ｖｏｕｔ（ｊω）を得ることが可能となる。

Here, when an inductance value L that satisfies "ωL=1/ωC" is selected, "I _L =−I _C " is obtained. parallel resonance. At this time, since an infinite impedance exists between the measuring device 100 and the resonant circuit 400, even if the capacitance component 500 is connected to the secondary winding 320, the power transformer It becomes possible to obtain the output voltage Vout(jω) of the 300 unit.

The variable inductor 160 includes a cylindrical coil winding 160A and an iron core 160B inserted through the coil winding 160A. Actuator 170B is mechanically connected to iron core 160B.

Then, control unit 170A monitors the value of ammeter 190 connected to wiring 180 between voltmeter 130 and variable inductor 160 so that the current value measured by ammeter 190 becomes zero. Similarly, the value of variable inductor 160 is adjusted by moving iron core 160B in and out along the axial direction of coil winding 160A to change the magnetic flux density (so that resonant circuit 400 is in parallel resonance).

As a result, the measuring device 100 can obtain the output voltage Vout(jω) of the power transformer 300 alone while the auxiliary equipment including the capacitance component 500 is connected to the power transformer 300. .

===Frequency Response Waveform Generator===
FIG. 2 is a block diagram showing an example of a frequency response waveform generating device using the measuring device according to this embodiment.

When diagnosing whether the power transformer 300 is operating in a sound state, the frequency response waveform generation device 200 measures the input voltage Vin(jω ) and the output voltage Vout(jω), and generates a frequency response waveform from the transfer function.

The frequency response waveform generation device 200 includes an input section 210, a transfer function calculation section 220, a frequency response waveform generation section 230, a storage section 240, and an output section 250 as means for realizing the above functions. .

The input unit 210 is supplied with information indicating the input voltage Vin(jω) and the output voltage Vout(jω) from the measuring device 100, and is an interface that connects a signal path between the measuring device 100 and the frequency response waveform generating device 200. is.

The transfer function calculator 220 is supplied with information indicating the input voltage Vin(jω) and the output voltage Vout(jω) from the input unit 210, and is defined by, for example, Equation (4) below for each measurement frequency. A transfer function H(jω) is calculated. Although the transfer function H(jω) is defined as a function indicating the voltage ratio, it may be defined as a function indicating the winding impedance or admittance. Transfer function H(jω) is stored in storage area 240A of storage unit 240 .

周波数応答波形生成部２３０は、記憶部２４０の記憶領域２４０Ａから読み出される伝達関数Ｈ（ｊω）を繋ぎ合わせて周波数応答波形を生成する。周波数応答波形を示す情報は、記憶部２４０の記憶領域２４０Ｂに記憶される。

The frequency response waveform generating section 230 connects the transfer functions H(jω) read from the storage area 240A of the storage section 240 to generate a frequency response waveform. Information indicating the frequency response waveform is stored in storage area 240B of storage unit 240 .

The storage unit 240 has the storage areas 240A and 240B described above. Note that the storage unit 240 may be one storage unit that divides one storage area into two storage areas 240A and 240B, or may be two storage units each having two storage areas 240A and 240B. may

The output unit 250 outputs information indicating the frequency response waveform read out from the storage area 240B of the storage unit 240 to a subsequent diagnostic device (not shown).

The diagnostic device compares, for example, the current frequency response waveform of the power transformer 300 supplied from the output unit 250 with a preset frequency response waveform indicating that the power transformer 300 is healthy, Whether or not the power transformer 300 is operating in a sound state is diagnosed according to the degree of divergence between the two waveforms.

=== Operation of measuring device ===
FIG. 3 is a flow chart showing an example of the operation of the measuring device according to this embodiment. It should be noted that the main body of the operation in FIG. 3 is the control section 170A.

First, the control unit 170A sweeps the input voltage Vin(jω) so that the frequency of the input voltage Vin(jω) generated by the input voltage generator 110 continuously changes from the first measurement frequency to the second measurement frequency. is started (step S1).

Next, the controller 170A controls the actuator 170B to move the iron core 160B along the axial direction of the coil winding 160A so that the current value measured by the ammeter 190 becomes zero (resonance The value of variable inductor 160 is adjusted (step S2) so that circuit 400 is in parallel resonance.

Next, the control section 170A determines whether or not the frequency of the input voltage Vin(jω) is the second measurement frequency (step S3). If the frequency of the input voltage Vin(jω) is not the second measurement frequency (step S3: NO), the processing after step S2 is executed again. On the other hand, if the frequency of the input voltage Vin(jω) is the second measurement frequency (step S3: YES), the series of processing ends.

As a result, the impedance between the measuring device 100 and the capacitance component 500 can be made infinite by causing the resonance circuit 400 to resonate in parallel. , it is possible to obtain the output voltage Vout(jω) of the power transformer 300 alone.

===Summary===
As described above, the power Based on the output voltage Vout(jω) output from the transformer 300 according to the change in the frequency of the input voltage Vin(jω), the frequency response waveform generator 200 generates a frequency response from the first measurement frequency to the second measurement frequency. A transfer function H(jω) corresponding to each measurement frequency is calculated, and an input voltage Vin(jω) to the power transformer 300 is generated so as to generate a frequency response waveform of the power transformer 300 from the transfer function H(jω). is input and the output voltage Vout (jω) output from the power transformer 300 is input to the frequency response waveform generation device 200, and is connected to the power transformer 300 Measure the current flowing through the resonant circuit 400 and the variable inductor 160 connected in parallel to the capacitance component 500 so as to form the resonant circuit 400 with the capacitance component 500 of the auxiliary equipment (instrument transformer, surge absorber, etc.) and a variable inductor so that the value of the current measured by the ammeter 190 becomes zero when the frequency of the input voltage Vin(jω) is changed from the first measurement frequency to the second measurement frequency. and a controller 170 that controls the value of 160 . As a result, the impedance between the measuring device 100 and the capacitance component 500 can be made infinite. of output voltage Vout(jω) can be obtained. In other words, it is possible to shorten the power failure work time when performing the frequency response analysis of the power transformer 300 .

Also, the variable inductor 160 includes a cylindrical coil winding 160A and an iron core 160B inserted into the coil winding 160A. , includes an actuator 170B for moving the iron core 160B in and out of the coil winding 160. As shown in FIG.

=== Other examples of measuring devices ===
FIG. 4 is a circuit block diagram showing another example of the measuring device according to this embodiment. The same numbers are given to the same components as those of the measuring apparatus 100 shown in FIG. 1, and the description thereof is omitted.

Measuring device 700 differs from measuring device 100 in that control device 710 is provided instead of control device 170 and variable capacitor 600 is connected in series to capacitance component 500 .

A variable capacitor 600 is connected in series with the capacitance component 500 in order to change the capacitance value according to the frequency of the input voltage Vin(jω). The variable capacitor 600 may have, for example, a structure in which the facing area of the electrode plates rotating the shaft or the distance between the electrodes is changed, or a plurality of capacitors each having a fixed capacitance value may be connected in series or in parallel. , and selectively connecting a plurality of capacitors by a switch.

The control device 710 includes a control section 710A and an actuator 710B. The control unit 710A controls the current value measured by the ammeter 190 to be zero.
The values of variable inductance 160 and variable capacitor 600 are adjusted by controlling actuator 710B. Actuator 710B has a structure for moving iron core 160B of variable inductor 160 along the axial direction of coil winding 160A. Furthermore, the actuator 710B has a structure for changing the facing area of the electrode plates of the variable capacitor 600 and the distance between the electrode plates, and switching switches for selectively connecting to a plurality of capacitors. Note that the switch may be electrically switched according to an instruction from the control section 710A.

As a result, the impedance between the measuring device 700 and the capacitance component 500 can be made infinite by causing the resonance circuit 800 to resonate in parallel. , it is possible to obtain the output voltage Vout(jω) of the power transformer 300 alone.

It should be noted that the above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit and interpret the present invention. The present invention may be modified and improved without departing from its spirit, and the present invention also includes equivalents thereof. For example, in FIG. 4, the value of at least one of the variable inductor 160 and the variable capacitor 600 may be adjusted in order to resonate the resonant circuit 400 .

100, 700 Measuring device 110 Input voltage generator 120 Resistors 130, 140 Voltmeter 150 Switch 160 Variable inductor 160A Coil winding 160B Iron cores 170, 710 Control devices 170A, 710A Control units 170B, 710B Actuator 180 Wiring 190 Ammeter 200 Frequency response Waveform generator 210 Input unit 220 Transfer function calculator 230 Frequency response waveform generator 240 Storage units 240A, 240B Storage area 250 Output unit 300 Power transformer 310 Primary winding 320 Secondary windings 400, 800 Resonant circuit 500 Capacitance Component 600 variable capacitor

Claims (7)

When the frequency of the sine wave signal input to the first electrical device is changed from a first measurement frequency to a second measurement frequency higher than the first measurement frequency, the frequency of the sine wave signal from the first electrical device A frequency response waveform generator calculates a transfer function corresponding to each measurement frequency from the first measurement frequency to the second measurement frequency based on the output signal output according to the change in the transfer function, Inputting the sine wave signal to the first electrical device and inputting the output signal output from the first electrical device to the frequency response waveform generating device so as to generate a frequency response waveform of the first electrical device A measuring device used to
a variable inductor connected in parallel to the capacitance component so as to form a resonance circuit with the capacitance component of a second electrical device connected to the first electrical device;
an ammeter that measures the current flowing through the resonant circuit;
The value of the variable inductor is controlled such that the current value measured by the ammeter becomes zero when the frequency of the sine wave signal is changed from the first measurement frequency to the second measurement frequency. a controller;
A measuring device comprising: The variable inductor includes a cylindrical coil winding and an iron core inserted into the coil winding,
The measuring device according to claim 1 , wherein the control device includes an actuator that moves the iron core in and out of the coil winding so that the current value measured by the ammeter becomes zero. . A variable capacitor connected in series with the capacitance component,
The controller controls the variable capacitor so that the value of the current measured by the ammeter becomes zero when the frequency of the sine wave signal is changed from the first measurement frequency to the second measurement frequency. The measuring device according to claim 1, wherein the value of is controlled. The first electrical device is a power transformer,
The measuring device according to any one of claims 1 to 3, wherein the second electrical device is a voltage transformer or a surge absorber. When the frequency of the sine wave signal input to the first electrical device is changed from a first measurement frequency to a second measurement frequency higher than the first measurement frequency, the frequency of the sine wave signal from the first electrical device A frequency response waveform generator calculates a transfer function corresponding to each measurement frequency from the first measurement frequency to the second measurement frequency based on the output signal output according to the change in the transfer function, Inputting the sine wave signal to the first electrical device and inputting the output signal output from the first electrical device to the frequency response waveform generating device so as to generate a frequency response waveform of the first electrical device A measuring method for a measuring device used for
a first step of connecting a variable inductor in parallel to said capacitance component so as to form a resonant circuit with said capacitance component of a second electrical device connected to said first electrical device;
a second step of measuring the current flowing into the resonant circuit with an ammeter;
The value of the variable inductor is controlled such that the current value measured by the ammeter becomes zero when the frequency of the sine wave signal is changed from the first measurement frequency to the second measurement frequency. a third step;
A measuring method comprising: The variable inductor includes a cylindrical coil winding and an iron core inserted into the coil winding,
6. The third step includes a fourth step of moving the iron core in and out of the coil winding by an actuator so that the value of the current measured by the ammeter becomes zero. The measurement method described in . In the third step, the current value measured by the ammeter becomes zero when the frequency of the sine wave signal is changed from the first measurement frequency to the second measurement frequency, The measuring method according to claim 5, further comprising controlling a value of a variable capacitor connected in series with the capacitance component.

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