JP7471127B2 - MEASUREMENT ASSISTANT DEVICE AND MEASUREMENT SYSTEM INCLUDING THE MEASUREMENT ASSISTANT DEVICE - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies. The manuscript was sent by email to the Secretariat of the 2019 National Convention of the Institute of Electrical Equipment Engineers of Japan on June 4, 2019.

Application of Article 30, Paragraph 2 of the Patent Act Lecture given at the 2019 National Convention of the Institute of Electrical Installation Engineers of Japan held at Fukuoka Institute of Technology on August 29, 2019

Article 30, paragraph 2 of the Patent Act applied. Manuscript sent to the Tokyo Electric Power Association on March 13, 2020.

The present invention relates to a measurement auxiliary device that assists in the safe measurement of a high-voltage portion of a measurement target, and a measurement system equipped with the measurement auxiliary device.

The deterioration of power quality in power distribution systems due to harmonic currents caused by the widespread use of inverter equipment has long been a problem.

In addition, electrical equipment is generally equipped with a leading-phase capacitor to improve the power factor. In such cases, a reactor is usually provided to prevent an increase in harmonic current caused by the installation of the leading-phase capacitor equipment and to control the current when the leading-phase capacitor is turned on.

Due to the deterioration of power supply quality described above, harmonic currents flow steadily into leading-phase capacitor equipment, and in the past there have been many cases where reactors attached to leading-phase capacitor equipment have burned out. Hereinafter, this type of reactor burnout will be referred to as "burnout due to steady-state harmonic currents."

Cases of "burning due to steady-state harmonic currents" have been on the decline due to measures to increase reactors' tolerance to harmonics.

For example, Patent Document 1 discloses a configuration in which a voltage rise suppression means is connected to a reactor to suppress the rise in voltage caused by the passage of current containing harmonics, in order to prevent harmonic interference in the reactor at low cost without increasing the size of the reactor connected in series to a phase-leading capacitor.

Japanese Patent Application Laid-Open No. 10-69322

However, in recent years, due to further deterioration in the power quality of the power distribution system, a resonance phenomenon occurs between the power distribution system and the leading-phase capacitor equipment when the leading-phase capacitor equipment is turned on, causing a current several times larger than the steady-state harmonic current to flow into the leading-phase capacitor equipment, resulting in an increasing number of cases in which the reactor burns out in a relatively short period of time. Hereinafter, this type of reactor burning out will be referred to as "burning out due to the resonance phenomenon."

Since the countermeasures for "burning due to steady-state harmonic currents" and "burning due to resonance phenomena" are different, if a burn accident occurs, it is necessary to observe (measure) the current flowing into the leading-phase capacitor equipment, identify the cause, and then take appropriate measures.

Generally, when measuring the voltage and current at high-voltage points in electrical equipment, a transformer or current transformer is used to convert the voltage and current into low-voltage, small-current signals, which are then displayed and measured using a voltmeter, ammeter, etc.

However, in a leading-phase capacitor installation in which multiple capacitors are connected in parallel, the current value per bank of capacitors is a fixed value proportional to the capacitor capacity, so only the ON/OFF state is managed and ammeters and current transformers are often not installed.

In addition, most measuring instruments are not designed to directly measure high-voltage circuits, and normal measuring instruments cannot directly measure the current flowing through leading-phase capacitor equipment, which is a high-voltage circuit.

On the other hand, in circuits other than those using leading-phase capacitor equipment, it is common to install an ammeter and a current transformer because the load fluctuates.

Therefore, as shown in FIG. 6, as a second best measurement method, a current transformer 41 is provided on the low voltage side of a current transformer 52 that sends a current signal to an ammeter 51 provided in the electric circuit of the power receiving main trunk. In addition, a current transformer 41 is provided on the low voltage side of each of the current transformers 53 to 55 that sends a current signal to an ammeter 51 provided in the electric circuit of each circuit. Then, the current value on the low voltage side of the current transformer 41 of the power receiving main trunk and the current value on the low voltage side of the current transformer 41 of each circuit are measured. After the measurement, each measurement data is added and subtracted using analysis software or spreadsheet software to calculate the current value flowing into the leading-phase capacitor equipment 48. In detail, the current values on the low voltage side of the current transformer 41 related to each circuit are added together. Then, the total value is subtracted from the current value on the low voltage side of the current transformer 41 related to the power receiving main trunk to calculate the current value flowing into the leading-phase capacitor equipment 48.

In this measurement method, the measurements used are steady-state average values, so it is possible to calculate the steady-state harmonic current trends to a certain extent. However, it is not possible to calculate transient current waveforms (time-dependent changes), such as sudden changes that occur when resonance occurs.

To use this measurement method to calculate the waveform (time progression) of the transient current flowing into the leading-phase capacitor equipment, it is necessary to precisely measure the AC sine wave in units of several milliseconds, rather than the effective value of the current, and use each of these measurement data to calculate the value of the current flowing into the leading-phase capacitor equipment 48. However, in this case, the amount of measurement data would be enormous, making practical application unrealistic.

In order to address the above-mentioned problems, the present invention aims to provide a measurement auxiliary device and a measurement system equipped with the measurement auxiliary device that can calculate the waveform (time progression) of the transient current flowing into a leading-phase capacitor equipment without generating an enormous amount of measurement data.

In order to achieve the above object, the present invention relates to a method for manufacturing a semiconductor device comprising the steps of:
A measurement auxiliary device that assists in measuring a current flowing into a leading-phase capacitor device connected to an electric circuit of a power receiving main trunk ,
It is electrically connected to a current transformer provided in the electric circuit of the power receiving main trunk, and is also electrically connected to a current transformer provided in each circuit connected to the electric circuit of the power receiving main trunk ,
The electrical signal output from the current transformer provided in the electric circuit of the power receiving main trunk is combined with the electrical signal output from the current transformer provided in each circuit,
outputting the synthesized electrical signal as an electrical signal representing the current flowing into the leading-phase capacitor device ;
The measurement auxiliary device includes a signal conversion unit provided in correspondence with each of the current transformers and configured to receive an input of an electrical signal related to the corresponding current transformer;
a signal processing unit that receives a connection operation between the signal conversion units from a user and adds or subtracts the electrical signal in accordance with the connection between the signal conversion units performed by the user;
the signal conversion unit is provided with a plurality of electric paths having different resistance values, accepts a selection of an electric path to be conducted from a user, converts the inputted electric signal into an electric signal related to a voltage drop corresponding to the resistance value of the electric path selected by the user, and outputs the electric signal;
The signal processing unit is a measurement assistant device that adds or subtracts the converted electrical signals in accordance with the connections between the signal conversion units made by a user, thereby synthesizing the electrical signals .

The invention according to claim 2 is as follows:
A measurement system comprising the measurement auxiliary device according to claim 1 and a measuring instrument that displays or records a measurement result,
The measuring device is a measuring system that displays or records the combined electrical signal received from the measuring assistant device for a predetermined time after the combined electrical signal exceeds a predetermined threshold.

The present invention makes it possible to measure the waveform (time transition) of the transient current flowing into a leading-phase capacitor device. Therefore, it is possible to precisely record the amount of current flowing in when a harmonic induction phenomenon occurs and the duration of the phenomenon, etc.

As a result, even if a burn accident occurs, it is possible to identify the cause and take appropriate measures based on the waveform (time progression) of the transient current flowing into the leading-phase capacitor equipment.

1 is a diagram showing an overall configuration of a measurement system according to a first embodiment of the present invention; 1A and 1B are enlarged views of a portion of the measurement system for the embodiment 1, in which (a) is an enlarged view of the location where the ammeter 51 is provided in the electrical path of the power receiving main trunk, and (b) is an enlarged view of the location where the ammeter 51 is provided in the electrical path of the circuit. 1 is a diagram showing a configuration of a measurement auxiliary device in a measurement system according to a first embodiment of the present invention; 3 is a diagram showing a configuration of a signal conversion unit of the measurement auxiliary device according to the first embodiment; FIG. 1 is a diagram showing the time progression of an electrical signal flowing into a phase-leading capacitor device and output to a measuring device in a measurement system according to the first embodiment of the present invention. FIG. FIG. 1 is a diagram showing an overall configuration of a conventional measurement system.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the attached drawings. However, the components described in this embodiment are merely examples, and are not intended to limit the scope of the present invention to only those components.

<First embodiment>
Fig. 1 is a diagram showing an overall configuration of a measurement system according to the present embodiment 1. In detail, Fig. 1 shows a state in which the measurement system according to the present embodiment 1 is installed in a power distribution system of an electric power consumer. The measurement system according to the present embodiment 1 includes a current transformer 31, a measurement assistant device 10, and a measurement instrument 20.

As shown in FIG. 2(a), an ammeter 51 is provided via a current transformer 52 on the electric circuit of the power receiving main trunk of the power receiving and distribution system of the power consumer. A current transformer 31 according to the measurement system of the first embodiment is provided on the low-voltage side of the current transformer 52. In FIG. 1, there are three circuits (power feeders) connected to the load 37. As shown in FIG. 2(b), an ammeter 51 is provided on each circuit connected to the load 37 via one of the current transformers 53 to 55. The current transformers 52 to 55 use an iron core and a coil, and are so-called CTs (Current Transformers) that generate a current on the secondary side (low-voltage side) at a ratio (current transformation ratio, CT ratio) according to the number of turns of the coil to facilitate measurement. The current transformers 52 to 55 usually convert 0 (A) to a large current to 0 (A) to 5 (A) or 0 (A) to 1 (A), etc. A current transformer 31 according to the measurement system of the first embodiment is provided on the low voltage side of the current transformers 52 to 55. The current transformer 31 is a clamp for a measuring device. In the first embodiment, the current transformers 52 to 55 are used to convert the input current and output the converted current, but the present invention is not limited to this configuration. Any configuration may be used as long as the input electrical signal, such as a current signal or voltage signal, is converted and the converted electrical signal is output. Therefore, for example, the input electrical signal may be converted into a current, and a voltage may be output as the converted electrical signal.

<Configuration of measurement assistant device 10>
The measurement auxiliary device 10 is connected to each current transformer 31, and receives the converted electric signal (secondary electric signal) output from each current transformer. More specifically, the electric signal received from the current transformer 31 related to the power receiving main trunk is called a power receiving point electric signal, and the electric signal received from the current transformer 31 of each circuit is called a feeder (power supply) electric signal. In the first embodiment, the measurement auxiliary device 10 receives a current signal from each current transformer 31 as an electric signal.

Furthermore, the measurement assistance device 10 is connected to the measuring instrument 20.

In other words, the measurement auxiliary device 10 combines the electrical signal (receiving point electrical signal) output from the current transformer 31 installed in the electrical circuit of the power receiving main trunk with the electrical signal (feeder electrical signal) output from the current transformer 31 installed in each circuit, and outputs the electrical signal flowing into the leading-phase capacitor equipment 38 to the measurement instrument 20.

The configuration of the measurement assistant device 10 will be described in detail below with reference to FIG. 3. The measurement assistant device 10 has a signal conversion unit 11 and a signal processing unit 12. The signal conversion unit 11 is provided corresponding to a current transformer and receives the input of an electrical signal related to the corresponding current transformer.

For example, in FIG. 3, the leftmost signal converter 11 accepts an input of an electrical signal related to current transformer 53, the second signal converter 11 from the left accepts an input of an electrical signal related to current transformer 54, and the third signal converter 11 from the left accepts an input of an electrical signal related to current transformer 55. The fourth signal converter 11 from the left accepts an input of an electrical signal related to current transformer 52.

Here, the configuration of the signal conversion unit 11 will be described in detail with reference to FIG. 4. The signal conversion unit 11 is provided with a plurality of electric paths with different resistance values. As shown in FIG. 4, 16 electric paths, electric paths 1 to 16, are provided. For example, the resistance value of electric path 1 is 6K (Ω) because a resistor of 6K (Ω) is provided. The resistance value of electric path 5 is 15K (Ω) because resistors of 6K (Ω), 1.5K (Ω), 2.5K (Ω), 2K (Ω), and 3K (Ω) are provided. In this way, the user can select 16 electric paths with different resistance values, so that it is possible to accommodate almost all commonly used current transformation ratios (CT ratios). In FIG. 4, the user operates the selector 111, and as a result, electric path 3 is in a conductive state.

However, general measuring instruments, including the measuring instrument 20 according to the first embodiment, are designed to have a high input impedance and minimize the current flowing into the measuring instrument, because problems such as heat generation can occur when a large current flows. Therefore, when the measurement auxiliary device 10 is connected to the measuring instrument 20, the measuring instrument 20 acts as an infinite resistor, and the current flowing into the measuring instrument 20 is very small. Therefore, most of the current (electrical signal) input to the signal conversion unit 11 through the electrical path 0 passes from point A through all 16 resistors provided in the signal conversion unit 11 (note that the voltage drops by the amount that passes through the 16 resistors), flows through point B, and is output to the outside of the signal conversion unit 11 through the electrical path 30. On the other hand, when the user operates the selector 111 and the electrical path 3 is in a conductive state, an electrical signal related to the voltage (6K+1.5K+2.5K (Ω)) corresponding to the voltage drop from point A to point C is extracted. In other words, the current input to the signal conversion unit 11 is converted to "5/100" as an electrical signal corresponding to the voltage drop from point A to point C, and is output from the signal conversion unit 11 via the electrical circuit 20.

In this way, the selector 111 of the signal conversion unit 11 accepts the selection of the electrical path from the user and converts the input electrical signal at an appropriate ratio, so that the current transformation ratios can be matched even if the current transformation ratios of the current transformers 52 to 55 are different. As a result, the electrical signals flowing into the leading-phase capacitor equipment 38 can be appropriately combined.

For example, if the current transformation ratios of current transformers 53, 54, and 55 are 5/100, and the current transformation ratio of current transformer 52 is 5/500, and if the same current of 100 (A) flows through each circuit, a current of 5 (A) flows through the low-voltage path side of current transformers 53 to 55, and a current of 1 (A) flows through the low-voltage path side of current transformer 52. In other words, even if the same current of 100 (A) flows through each circuit, there is a five-fold difference between the current flowing through the low-voltage path side of current transformers 53 to 55 and the current flowing through the low-voltage path side of current transformer 52. Therefore, the selector 111 for each signal conversion unit 11 corresponding to current transformers 53 to 55 is operated to bring electrical circuit 3 into a conductive state, and the selector 111 for the signal conversion unit 11 corresponding to current transformer 52 is further operated to bring electrical circuit 13 into a conductive state, so that the current transformation ratio of all electrical signals is adjusted to "5/1000" based on the resistance ratio.

Then, the signal processing unit 12 receives a connection operation between the signal conversion units 11 from the user, and adds, subtracts, or passes the electrical signal depending on the connection between the signal conversion units 11 performed by the user.

For example, in FIG. 3, the user has connected the leftmost signal conversion unit 11 and the second signal conversion unit 11 from the left in series with opposite poles (positive and negative, or negative and positive). The second signal conversion unit 11 from the left and the third signal conversion unit 11 from the left are also connected in series with opposite poles.

On the other hand, the third signal conversion unit 11 from the left and the fourth signal conversion unit 11 from the left are connected in series with the same polarity (positive and positive, or negative and negative).

Furthermore, the fourth signal conversion unit 11 from the left and the rightmost signal conversion unit 11 are connected so that the electrical signal passes through without passing through the rightmost signal conversion unit 11.

By connecting each signal conversion unit 11 as described above, the signal processing unit 12 adds the electrical signals related to the current transformers 53 to 55 and subtracts the electrical signal related to the current transformer 52 from the electrical signal after this addition. As a result, the electrical signals flowing into the leading-phase capacitor equipment 38 are combined. The signal processing unit 12 then outputs the combined electrical signal to the measuring instrument 20.

The measuring instrument 20 is, for example, a digital oscilloscope, and displays and records measurement results such as the waveforms (time progression) of electrical signals such as input current signals and voltage signals.

<Waveform of Electrical Signal Flowing into Leading Phase Capacitor Equipment 38>
The auxiliary measurement device 10 instantaneously combines the electrical signals related to each measurement point and outputs the electrical signal flowing into the leading-phase capacitor equipment 38 to the measuring device 20. The auxiliary measurement device 10 performs this continuously, so that the measuring device 20 can recognize the time transition of the transient electrical signal flowing into the leading-phase capacitor equipment 38 as a waveform such as a sine wave, and display and record it, as shown in Fig. 5. Therefore, the measuring device 20 can precisely display and record the amount of inflow current when the harmonic induction phenomenon occurs and the duration of the phenomenon. For the sake of understanding, Fig. 5 shows not only the time transition of the transient current value flowing into the leading-phase capacitor equipment 38, but also the time transition of the main current value and the time transition of the load current value.

As a result, even if a burnout accident occurs, it is possible to identify the cause based on the waveform (time progression) of the transient current flowing into the leading-phase capacitor equipment 38 and then take appropriate measures.

<Modification>
In addition, in this embodiment example 1, a configuration is shown in which the measuring instrument 20 constantly displays and records the electrical signal related to the current flowing into the leading-phase capacitor equipment 38, which is output from the measurement auxiliary device 10, but this configuration is not limited to this.

For example, the measuring device 20 may be configured to display and record an electrical signal related to the current flowing into the leading-phase capacitor equipment 38 for a predetermined time (e.g., several msec) after the electrical signal exceeds a predetermined threshold value.

In this way, by configuring the measuring device 20 to display and record the electrical signal only when an abnormality occurs in which the electrical signal exceeds the threshold (i.e. an overcurrent occurs), it is possible to accurately obtain only the data necessary to identify the cause of the burn accident. This is also convenient as it prevents the amount of data recorded and stored in the measuring device 20 from becoming excessive.

In addition, in the first embodiment, the third signal converter 11 from the left and the fourth signal converter 11 from the left are connected in series with the same polarity to subtract the electrical signal related to the current transformer 52 of the power receiving main trunk, but this configuration is not limited to this. For example, the current transformer 31 related to the electric circuit of the power receiving main trunk of the power receiving and distribution system of the power consumer may be provided with the opposite polarity to the current transformers 31 related to each circuit, and the third signal converter 11 from the left and the fourth signal converter 11 from the left may be connected in series with the opposite polarity.

Furthermore, in the first embodiment, a configuration using one measurement auxiliary device 10 has been described, but the present invention is not limited to this configuration. If there are not enough signal conversion units 11 corresponding to the current transformers, it is possible to open the switch 112 (see FIG. 3) of the measurement auxiliary device 10 and connect and use multiple measurement auxiliary devices 10.

In addition, in the present embodiment 1, since it is common in electrical equipment for an ammeter 51 to be provided in the electric path of the power receiving main trunk and the electric path of each circuit via one of the current transformers 52 to 55, a configuration is shown in which a current transformer 31 is provided on the low-voltage side of each of the current transformers 52 to 55, but this configuration is not limited to this. For example, a configuration in which a current transformer 31 is provided directly in the electric path of the power receiving main trunk and the electric path of each circuit may also be used.

10: measurement auxiliary device, 11: signal conversion unit, 111: selector, 112: switch, 12: signal processing unit,
20: Measuring instrument,
31: current transformer, 37: load, 38: phase-leading capacitor equipment,
41: current transformer, 48: phase-advancing capacitor equipment,
51: ammeter, 52 to 55: current transformers

Claims (2)

A measurement auxiliary device that assists in measuring a current flowing into a leading-phase capacitor device connected to an electric circuit of a power receiving main trunk ,
It is electrically connected to a current transformer provided in the electric circuit of the power receiving main trunk, and is also electrically connected to a current transformer provided in each circuit connected to the electric circuit of the power receiving main trunk ,
The electrical signal output from the current transformer provided in the electric circuit of the power receiving main trunk is combined with the electrical signal output from the current transformer provided in each circuit,
outputting the synthesized electrical signal as an electrical signal representing the current flowing into the leading-phase capacitor device ;
The measurement auxiliary device includes a signal conversion unit provided in correspondence with each of the current transformers and configured to receive an input of an electrical signal related to the corresponding current transformer;
a signal processing unit that receives a connection operation between the signal conversion units from a user and adds or subtracts the electrical signal in accordance with the connection between the signal conversion units performed by the user;
the signal conversion unit is provided with a plurality of electric paths having different resistance values, accepts a selection of an electric path to be conducted from a user, converts the inputted electric signal into an electric signal related to a voltage drop corresponding to the resistance value of the electric path selected by the user, and outputs the electric signal;
the signal processing unit adds or subtracts the converted electrical signals in accordance with connections between the signal conversion units made by a user, thereby synthesizing the electrical signals . A measurement system comprising the measurement auxiliary device according to claim 1 and a measuring instrument that displays or records a measurement result,
The measuring device displays or records the combined electrical signal received from the measurement assistant device for a predetermined time after the combined electrical signal exceeds a predetermined threshold.