JP2001124806A - Three-phase power meter, three-phase watt-hour meter, and connection state judging method of them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wrong measurement due to wrong connection and perform repair in its early stages, by judging the connection state of a power supply wire connecting between a three-phase power meter, a current transformer and a voltage transformer. SOLUTION: The line voltages of distribution lines 1-3 are converted into voltage digital values by 1- and 3-side voltage converting circuits 13, 14. Respective 1- and 3-side load currents of the distribution lines 1 and 3 are converted into current digital values by 1- and 3-side current converting circuits 11 and 12. With the voltage and current digital values and power values computed by a multiplication circuit 15 multiplying the line voltages by the load currents, positive- and negative-phase-sequence connection or wrong connection is determined by a CPU 16 and the judged result is displayed by a display circuit 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase watt-hour meter for measuring the amount of power of a three-phase power circuit and a three-phase power meter for measuring three-phase power, and more particularly to a power supply line connected to these meters. And the determination of the connection state.

[0002]

2. Description of the Related Art FIG.
FIG. 61 is a block diagram showing a configuration of a conventional three-phase power measuring device capable of detecting an erroneous connection in the three-phase power measuring device disclosed in Japanese Unexamined Patent Publication No. 61-61. 1, 2, and 3 are distribution lines of a three-phase three-wire circuit;
a, 20b, 20c are distribution line 1, distribution line 3, and distribution line 2
, 21a, 21b are current transformers connected to the three-phase three-wire circuits 1-3.

[0003] Reference numeral 22 denotes voltage connection lines 20a, 20b and 20c.
Power supply lines connected to the current transformers 21a and 21b, 23
Are the voltage connection lines 20a, 20b, 20c
And a voltage input unit 24 to which the voltage of each phase is input. The current transformers 21a and 21b are connected via a power supply line 22, and the secondary current of the current transformers 21a and 21b is input to the voltage input unit 24. Current input section.

[0005] Reference numeral 25 denotes analog / digital conversion means for digitizing an inter-phase voltage input input to the voltage input unit 23 and a current input input to the current input unit 24, and 26 denotes digital data obtained by the analog / digital conversion means 25. An actual input voltage register 27 for storing a voltage input is an actual input current register for storing a current input digitized by the analog / digital conversion means 25.

Reference numeral 28 denotes a voltage phase sequence discriminating means for reading the phase sequence of the voltage input section 23 based on the data of the actual input voltage register 26 and discriminating between the normal sequence and the reverse sequence. The current phase sequence determining means 30 reads the phase sequence of the current input section 24 based on the current order, and determines whether the current sequence is the normal sequence or the reverse sequence. The voltage phase sequence determining device 28 and the current phase sequence determining device 29 determine the phase of the voltage. This is a voltage / current phase order comparing means for comparing whether the order and the current phase order match or not.

Numeral 31 indicates that the polarity of one of the two sets of current read data is reversed when the comparison result of the voltage / current phase sequence comparing means 30 does not match. Reference numeral denotes a corrected current register that stores two sets of current read data as they are, and reference numeral 32 denotes a power calculation unit that calculates three-phase power from the current data of the corrected current register 31 and the voltage data of the actual input voltage register 26.

Reference numeral 33 denotes an absolute value calculating means for calculating the absolute value of the power calculation result in the power calculating means 32; 34, a display means for displaying the calculation result of the calculating means; 35, a voltage input section 23; 24, analog / digital conversion means 2
5, real input voltage register 26, real input current register 27 to be stored, voltage phase order determining means 28, current phase order determining means 2
9, a three-phase power measuring device comprising a voltage / current phase sequence comparing means 30, a corrected current register 31, a power calculating means 32, an absolute value calculating means 33, and a display means 34.

[0008] The operation of the three-phase power meter 35 will be described below. Voltage and current input unit 2 input to voltage input unit 23
The current input to 4 is converted from analog to digital by the A / D converter 25 and input to the real input voltage register 26 and the real input current register 27, respectively. The current phase sequence determining means 29 examines the phase sequence of the current i1 of the connection terminal 24a and the current i2 of the connection terminal 24b of the current input unit 24 based on the current data of the actual input current register 27, and finds "i2 is i1
Is the normal phase order in which is the lag phase, or the reverse phase order in which i1 is the advanced phase with respect to i2.

The voltage phase sequence determining means 28 determines the voltage v1 between the connection terminals 23a-23c of the voltage input unit 23 and the connection terminals 23b-23c based on the voltage data of the actual input voltage register 26.
By examining the phase order of the voltage v2 between them, it is determined whether the phase order is “normal phase where v1 is a lagging phase with respect to v2” or reverse phase order where “v1 is a leading phase with respect to v2”.

The voltage / current phase sequence comparing means 30 determines that the phase sequence is "match" when the voltage phase sequence and the current phase sequence are both the positive phase sequence or the opposite phase sequence, and determines the voltage phase sequence and the current phase sequence. When one of the order is the normal phase order and the other is the reverse phase order, it is determined that the phase order is “mismatch”. When the result of the voltage / current phase sequence comparing means 30 is “mismatch”, the corrected current register 31
By reversing the polarity of one of the two current inputs (for example, i1), a "corrected current" is created and stored, and in the case of "match", the two current data are stored as they are.

The power calculation means 32 includes a correction current register 31
And the data of the actual voltage register 26 are input to calculate the power, and the absolute value conversion means 33 obtains the absolute value of the calculation result of the power calculation means 32, thereby obtaining the voltage connection lines 20a, 20
b, 20c may be connected in any order, and the current transformers 21a, 2c
Even if the coupling direction of 1b is arbitrary, correct power can always be obtained.

[0012]

Since the conventional three-phase power measuring device is configured as described above, the voltage connecting lines 20a, 20b, and 20 to the distribution line 1, the distribution line 2, and the distribution line 3 are provided.
In the case where the connection order of the current transformers 20c is arbitrary and the method of coupling the current transformers 21a and 21b is arbitrary, correct power can be measured, but, for example, the current transformers 21a and 21b are switched, Further, when the connection of the input terminal 24a of the current input unit 24 is reversed, i1 has a delayed phase with respect to i2, so that there is a problem that power cannot be measured correctly.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and there is a problem with connection between a three-phase power meter and a three-phase watt-hour meter and a power supply line connected to a current transformer and a transformer. It is an object of the present invention to provide a three-phase power measuring device and a three-phase watt-hour meter that can prevent erroneous measurement due to making a connection and detect the connection state so that restoration can be performed at an early stage.

[0014]

SUMMARY OF THE INVENTION A three-phase power measuring device and a three-phase watt-hour meter according to the present invention include: an introduction means for introducing a line voltage and a load current of a distribution line via a connection line; -Phase power measuring device having a multiplication means for multiplying the multiplication result by the load current to obtain an integration result, and the introduction means, the multiplication means, and the integration means for integrating the multiplication result of the multiplication means to obtain an integrated power And a connection state determining means for determining whether the connection state of the connection line is correct or not based on the introduced line voltage, load current, and multiplication result.

Also, the three-phase power measuring device and the three-phase watt-hour meter according to the present invention provide a method for determining the connection state of a three-phase watt-hour meter. A connection state determination method for a three-phase power measurement device that determines a connection state of a three-phase power measurement device having a multiplication unit that obtains a multiplication result by multiplying a voltage and a load current; and the introduction unit and the multiplication unit. The three-phase watt-hour meter connection state determination method for determining the connection state of the three-phase watt-hour meter having integration means for integrating the multiplication result of the multiplication means to obtain integrated power; This is to determine whether the connection state of the connection line is correct or not based on the current and the result of the multiplication.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a connection diagram in a case where a power supply line is correctly connected to the three-phase watt-hour meter according to Embodiment 1 of the present invention (positive-phase order). In the figure, 1, 2, and 3 are distribution lines of a three-phase three-wire circuit, 4 is a three-phase watt-hour meter, and 5 is a line between the distribution lines 1 and 2 (hereinafter, 1).
A first-side transformer 6 measures the line voltage on the (side) side, and a three-side transformer 6 measures the line voltage between the distribution line 3 and the distribution line 2 (hereinafter, three sides).

Reference numeral 7 denotes a one-side current transformer for measuring a load current of the distribution line 1 (hereinafter, one-side load current), and reference numeral 8 denotes a load current of the distribution line 3 (hereinafter, three-side load current). Side current transformer, 9
Is the ground point. Reference numeral 22 denotes a power supply line that supplies outputs from the first transformer 5, the third transformer 6, the first current transformer 7, and the third current transformer 8 to the three-phase watt-hour meter 4.

FIG. 2 is a block diagram showing a configuration of the watt hour meter according to the first embodiment of the present invention. In the figure,
11 is a 1-side current conversion circuit for A / D converting the load current on the 1 side to a digital value proportional to the load current, and 12 is a 3-side current conversion circuit for converting the load current on the 3 side to a digital value proportional to the load current. It is.

Reference numeral 13 denotes a one-side voltage conversion circuit for converting the line voltage on the one side into a digital value proportional to the line voltage, and reference numeral 14 denotes a three-side voltage conversion circuit for converting the line voltage on the three side into a digital value proportional to the line voltage. , 15 multiply the output of the first-side current conversion circuit 11 by the output of the first-side voltage conversion circuit 13, multiply the output of the third-side current conversion circuit 12 by the output of the third-side voltage conversion circuit 14, A multiplication circuit that calculates the sum of the results and outputs the calculation result.

Reference numeral 16 denotes a power amount based on the output of the first current conversion circuit 11, the output of the third current conversion circuit 12, the output of the first voltage conversion circuit 13, the output of the third voltage conversion circuit 14, and the output of the multiplication circuit 15. Erroneous connection discriminating means for deciding whether the total connection is in normal phase order, reverse phase order or erroneous connection, and a multiplication circuit 1
5 is a CPU having an integrating means for calculating the amount of electric power by integrating the output of 5; 17 is a display circuit for displaying the incorrect connection determination result and the calculation result of the amount of electric power by the CPU 16;
A first timer provided inside or outside 16; 1
Reference numeral 9 denotes a second timer provided inside or outside the CPU 16.

Next, the normal-phase forward connection and the reverse-phase forward connection will be described. FIG. 3 is a vector diagram of a line voltage and a load current in the case of a power factor of 1 in a positive-sequence forward connection in a distribution line of a three-phase three-wire circuit. The load current on the first side is I1, and the load current on the third side is I1.
3. The line voltage on the 1 side is represented as V12, and the line voltage on the 3 side is represented as V32. φ is the power factor angle of the electric power which is the product of the line voltage and the load current. When the power factor is 1 in the positive-sequence sequential connection, φ = 0. φ1
Is the phase angle of the power on the one side, which is the product of the line voltage on the one side and the load current on the one side, and φ1 lags behind φ by 30 ° in the positive-sequence connection. Φ3 is 3 line voltage and 3
This is the power factor angle of the three-side power, which is the product of the side load currents. In the positive-sequence connection, φ3 leads 30 ° with respect to φ.

Therefore, the power W1 on the first side and the power W3 on the third side are represented by the following equations (1) and (2). W1 = V12 I1 cos (φ + 30 °) = V12 I1 cos (φ1) --- (1) W3 = V32 I3 cos (φ-30 °) = V32 I1 cos (φ3) --- (2) Line voltage V = V12 = V32 and load current I = I1 = I3, the power W measured by the watt hour meter is expressed by the following equation (3). ^{W = W1 + W2 = 3 1/2} · V1 cos φ ------------- (3)

FIG. 4 is a vector diagram of line voltage and load current in the case of a power factor of 1 in reverse-sequence forward connection in a distribution line of a three-phase three-wire circuit. The voltage input terminals P1 and P3 are connected in reverse to the positive-sequence connection shown in FIG.
Are connections that have been switched and replaced.

Next, with reference to FIG. 2, the incorrect connection discriminating means of the CPU 16 will be described. As a precondition for erroneous connection determination, it is assumed that the power factor is in the range of 0.5 to 1, that is, −60 ° <φ <60 ° in the normal-phase forward connection, and that the load is a balanced load. Therefore, as shown in FIGS. 5 and 6, in the normal-sequence forward connection, the range of φ1 is −30 ° <φ3 <90 ° (4) The range of φ3 is −90 ° <φ1 <30 ° −−−−− (5)

The erroneous connection determination means has first to sixth determination means. Each of the determination means will be described below. (First Discriminating Means) In the normal-phase forward connection, the polarity of the output of the multiplication circuit 15 is positive when −90 ° <φ <90 °, and when −60 ° <φ <60 °. , Multiplication circuit 15
Is negative, it is determined that the connection is incorrect.

(Second discriminating means) FIGS. 7A and 7B are waveform diagrams for explaining the second discriminating means. FIG. 7B shows a case where the phase angle is 30 ° lag, and FIG. This is an example in the case of a phase angle, and will be described with reference to FIGS. The CPU 16 inputs the one-side load current converted to the digital value in the one-side current conversion circuit 11 and the one-side line voltage converted to the digital value in the one-side voltage conversion circuit 13, and inputs the one-side line voltage. When the polarity changes, that is, when the polarity of the output of the one-side voltage conversion circuit 13 changes from positive to negative or changes from negative to positive, the first timer 18 and the second timer 19 start counting. When the polarity of the output of the first-side voltage conversion circuit 13 changes in the direction opposite to the time when the count is started, the count of the first timer 18 is stopped.

The CPU 16 determines whether the polarity of the load current on the one side changes in the same direction as the polarity change of the line voltage on the one side when the second timer 19 is started, that is, the one-side current conversion circuit 11 When the polarity of the output changes, the count of the second timer 19 is stopped.

The count time of the first timer 18 is T1,
Assuming that the count time of the second timer 19 is T2, the phase difference P1 between the line voltage on the one side and the load current on the one side is expressed by the following equation. P1 = T2 / T1 × 180 ° (6) When P1 is 180 ° or less, the phase is delayed by P1. When P1 is 180 ° or more, (360 ° −P1 ) Only the phase is advanced.

The phase difference P1 on one side is equal to the line voltage on one side and 1
Since the power factor angle φ1 of the power on the one side, which is the product of the load currents on the side, the power factor angle φ1 of the power on the one side can be obtained by calculating the equation (6) by the CPU 16. , P
When 1 is equal to or less than 180 °, φ1 = P1 and P1 is 1
In the case of 80 ° or more, φ1 = (360 ° −P1).

When −60 ° <φ <60 °, the power factor angle φ1 of the power on one side in the normal-phase forward connection is −30 ° <φ1 <9
0 °. (See FIG. 5) Therefore, the power factor angle φ1 of the power on one side is −30 ° <φ1
If the angle is not <90 °, it is determined that the connection is incorrect.
(See Fig. 7 (d))

(Third Discriminating Means) FIG. 8 is a waveform diagram for explaining the third discriminating means. FIG. 8 (b) shows a case where the phase angle is 90 °, and FIG. This is an example in the case of a phase angle, and will be described with reference to FIGS. The CPU 16 inputs the three-side load current converted to a digital value in the three-side current conversion circuit 12 and the three-side line voltage converted to a digital value in the three-side voltage conversion circuit 14, and inputs the three-side line voltage. When the polarity changes, that is, when the polarity of the output of the three-side voltage conversion circuit 14 changes from positive to negative or changes from negative to positive, the counts of the first timer 18 and the second timer 19 are started. When the polarity of the output of the third-side voltage conversion circuit 14 changes in the direction opposite to the time when the count starts, the count of the first timer 18 is stopped.

Also, the CPU 16 determines when the polarity of the load current on the third side changes in the same direction as the change in the polarity of the line voltage on the third side when the second timer 19 is started, that is, the third current conversion circuit 12 When the polarity of the output changes, the count of the second timer 19 is stopped. First timer 18
Is T1 and the count time of the second timer 19 is T2, the phase difference P3 between the line voltage on the third side and the load current on the third side is expressed by the following equation. P3 = T2 / T1.times.180.degree .---- (-)

When P3 is less than 180 °, the phase is delayed by P3, and when P3 is more than 180 °, 360 ° −
The phase is advanced by P3. Since the phase difference P3 on the third side is the power factor angle φ3 of the power on the third side, which is the product of the line voltage on the third side and the load current on the third side, the CPU 16 calculates the above equation (7). The power factor angle φ3 of the power on the third side can be obtained. When P3 is 180 ° or less, φ3 = P3, and when P3 is 180 ° or more, φ3 = 360 ° -P
3

When −60 ° <φ <60 °, the power factor angle φ3 of the power on the third side in the positive-sequence connection is −90 ° <φ3 <3.
0 °. Therefore, the power factor angle φ3 of the power on the third side is −90 ° <φ3
If the angle is not <30 °, it is determined that the connection is incorrect connection.
(See FIG. 8 (d))

(Fourth Discriminating Means) FIG. 9 is a waveform diagram for explaining the fourth discriminating means. FIG. 9 (b) shows a case of a 120 ° lagging phase angle, and FIG. This is an example in the case of a phase angle, and will be described with reference to FIGS. The CPU 16
When the polarity of the load current on the first side changes, that is, when the polarity of the output of the first current conversion circuit 11 changes from positive to negative or from negative to positive, the first timer 18 and the second timer When the count of 19 is started and the polarity of the output of the one-side current conversion circuit 11 changes in the direction opposite to the time when the count was started, the count of the first timer 18 is stopped.

The CPU 16 determines when the polarity of the load current on the third side changes in the same direction as the change in the polarity of the load current on the first side when the second timer 19 is started, ie, when the third current conversion circuit 12 When the polarity of the output changes, the count of the second timer 19 is stopped. First timer 18
Is T1 and the count time of the second timer 19 is T2, the phase angle PI between the load current on the first side and the load current on the third side is expressed by the following equation. PI = T2 / T1.times.180.degree .-- 8 (8)

When PI is 180 ° or less, the load current on the third side is delayed in phase by PI from the load current on the first side, and when PI is 180 ° or more, the load current on the third side is The phase is advanced by 360 ° -PI with respect to the load current. Therefore, the phase angle PI of the load current on the third side with respect to the load current on the first side can be obtained by performing the calculation of the equation (8) by the CPU 16.

In the case of a balanced load, 1
The phase angle of the load current on the third side with respect to the load current on the side is 120
°, the phase angle of the load current on the third side with respect to the load current on the first side is delayed by 120 ° when connected in reverse phase.
Therefore, when PI ≠ 120 ° and PI ≠ 240 °, it is determined that the connection is erroneous, and when PI = 120 °, it is determined that the connection is in reverse phase or connection is incorrect. (See FIG. 9 (d))

(Fifth Discriminating Means) FIG. 10 is a waveform diagram for explaining the fourth discriminating means. FIG. 10 (b) shows a case where the phase angle is 60 °, and FIG. This is an example in the case of a phase angle, and will be described with reference to FIGS. CPU16
When the polarity of the line voltage on the one side changes, that is, when the polarity of the output of the one-side voltage conversion circuit 13 changes from positive to negative or from negative to positive, the first timer 18 and the second timer The count of the first timer 18 is stopped when the polarity of the output of the one-side voltage conversion circuit 13 changes in a direction opposite to the time when the count is started.

The CPU 16 determines when the polarity of the line voltage on the third side changes in the same direction as the change in the polarity of the line voltage on the first side when the second timer 19 is started, When the polarity of the output changes, the count of the second timer 19 is stopped. First timer 18
Is T1 and the count time of the second timer 19 is T2, the phase angle PV between the line voltage on the first side and the line voltage on the third side is expressed by the following equation. PV = T2 / T1.times.180.degree .-- 9 (9)

When PV is equal to or less than 180 °, the line voltage on the third side is delayed in phase by PV from the line voltage on the first side, and when PV is 180 ° or more, the line voltage on the third side is The phase is advanced by (360 ° −PV) with respect to the line voltage. Therefore, the phase angle PV of the line voltage on the third side with respect to the line voltage on the first side can be obtained by calculating the above equation (9) by the CPU 16.

At the time of normal-phase forward connection, the phase of the line voltage at the third side with respect to the line voltage at the first side is advanced by 60 °. The phase is delayed by 60 °. Therefore, PV ≠ 60 ° and PV
When it is ≠ 300 °, it is determined that the connection is erroneous, and when PV = 60 °, it is determined that the connection is reversed-sequence connection or erroneous connection. (FIG. 10
(See (d))

(Sixth Discriminating Means) In the normal-phase forward connection, an output proportional to the instantaneous power is output from the multiplier circuit 15 to the CPU 16. Therefore, when the output of the multiplication circuit 15 is 0, it can be determined that the connection is incorrectly connected.

FIG. 11 is a flowchart showing the operation of the incorrect connection determination means of the three-phase watt-hour meter. The operation of the three-phase watt-hour meter having the above-described determination means will be described with reference to FIG. The line voltages of the distribution lines 1, 2, and 3 are input from the power supply line 22 to the first-side voltage conversion circuit 13, the third-side voltage conversion circuit 14, and the load current of the distribution lines 1 and 2 is converted to the first-side current conversion circuit 1.
When the current is input to the first and third current conversion circuits 12, the false connection detection is started.

(1) If the polarity of the output of the multiplying circuit 15 is negative, the first discriminating means discriminates an incorrect connection,
The display circuit 17 displays the incorrect connection connection, and the multiplication circuit 15
If the output polarity is positive, the process proceeds to step 2. (Step 1)

(2) In the second determining means, the power factor angle φ1 of the one-side power obtained by the CPU 16 from the output of the one-side current conversion circuit 11 and the output of the one-side voltage conversion circuit 13 is −30.
If not <90 °, it is determined that there is an incorrect connection, and the display circuit 17 displays the incorrect connection, and the power factor angle φ1 of the power on one side is −30 ° <φ1 <90 °. If so, go to step 3. (Step 2)

(3) In the third determining means, the power factor angle φ3 of the power on the third side obtained by the CPU 16 from the output of the current converter 12 and the output of the voltage converter 14 is -90.
If ° <φ3 <30 ° does not hold, it is determined that the connection is incorrect, and the display circuit 17 displays the incorrect connection. The power factor angle φ3 of the three-side power is −90 ° <φ3 <30 °. If so, go to step 4. (Step 3)

(4) If the phase angle PI of the load current obtained by the CPU 16 from the output of the first-side current conversion circuit 11 and the output of the third-side current conversion circuit 12 is 240 ° in the fourth determination means, the process proceeds to step 5. The load current phase angle PI = 12
If the angle is 0 °, the process proceeds to step 7 and the phase angle PI of the load current
If ≠ 240 ° and PI ≠ 120 °, it is determined that the connection is incorrect, and the display circuit 17 displays the connection. (Step 4)

(5) If the phase angle PV = 300 ° of the line voltage obtained by the CPU 16 from the output of the first-side voltage conversion circuit 13 and the output of the third-side voltage conversion circuit 14 in the fifth determination means, the process proceeds to step 6. Advance, line voltage phase angle PV ≠ 30
If the angle is 0 °, the connection is determined to be incorrect connection, and the display circuit 17 displays the incorrect connection. (Step 5)

(6) In the sixth judging means, when the output of the multiplying circuit 15 is 0, it is judged that the connection is erroneously connected, the display circuit 17 displays the connection of the erroneous connection, and the output of the multiplication circuit 15 is not 0. In this case, it is determined that the connection is in the normal sequence, and the display circuit 17 displays the normal connection. (Step 6)

(7) In the fifth determining means, when the phase angle PV of the line voltage obtained by the CPU 16 from the output of the first voltage conversion circuit 13 and the output of the third voltage conversion circuit is PV = 60 °, the phase is reversed. The connection is determined, and the display circuit 17 displays the reverse-phase forward connection. If the line voltage phase angle PV ≠ 60 °, the connection is determined to be erroneously connected, and the display circuit 17 displays the erroneous connection. (Step 7)

Next, a description will be given of the operation of determination in the case of incorrect connection. FIG. 12 is a connection diagram when the power supply lines of the three-phase watt-hour meter of the present invention are incorrectly connected, and FIG.
FIG. 13 is a vector diagram of a line voltage and a load current when the power factor is 1 in FIG. Compared with the connection diagram of FIG. 1 in the case of positive-sequence connection, the one-side current transformer 7 and the three-side current transformer 8 are switched and connected (I1 and I3 are switched). The power supply side terminal (k) and the load side terminal (l) of the three-side current transformer 8 are connected to the 1S and 1L terminals (the phase of I1 is further delayed by 180 °).

In the case of this erroneous connection, it is determined as follows. As shown in FIG. 13, the load current I3 on the third side leads the load current I1 on the first side by 60 °. Therefore,
When the erroneous connection determination is performed in accordance with the flowchart of FIG. 11, the fourth determination means, "the phase angle PI of the load current on the third side with respect to the load current I1 on the first side is PI {120} and PI # 240 In the case of ゜, it is determined that the connection is incorrect. "

In the above description, the operation of discriminating an incorrectly connected connection in which the first-side current transformer 7 and the third-side current transformer 8 are interchanged has been described. In the connection with the watt-hour meter 4, all the anti-sequence and erroneous connection connections formed by the combination can be similarly discriminated. By displaying the discrimination result on the display circuit 17, erroneous measurement can be performed. Can be prevented and the connection state can be sensed, so that restoration can be performed early.

Embodiment 2 Although the three-phase watt-hour meter has been described in the first embodiment, the present invention can be applied to a three-phase power meter that measures three-phase power. Further, the present invention can be applied to a three-phase watt-hour meter or a three-phase power meter as a connection state determination method.

[0056]

As described above, according to the present invention, the correctness or incorrectness of the connection state is determined by the connection state determination means or the connection state determination method, so that erroneous measurement can be prevented and the restoration can be performed early. it can.

[Brief description of the drawings]

FIG. 1 is a connection diagram showing a case in which a power supply line is correctly connected to a three-phase watt-hour meter (first order) in the first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a three-phase watt-hour meter according to Embodiment 1 of the present invention.

FIG. 3 is a vector diagram of a line voltage and a load current in the case of a power factor of 1 in a positive-sequence forward connection in a distribution line of a three-phase three-wire circuit.

FIG. 4 is a vector diagram of a line voltage and a load current in the case of a power factor of 1 in reverse-phase forward connection in a distribution line of a three-phase three-wire circuit.

FIG. 5 is a vector diagram showing a range of φ1 of a positive-phase forward connection in a distribution line of a three-phase three-wire circuit.

FIG. 6 is a vector diagram showing a range of φ3 of positive-phase forward connection in a distribution line of a three-phase three-wire circuit.

FIG. 7 is a waveform diagram illustrating a first determination unit according to the first embodiment of the present invention.

FIG. 8 is a waveform diagram illustrating a second determination unit according to the first embodiment of the present invention.

FIG. 9 is a waveform diagram illustrating a third determination unit according to the first embodiment of the present invention.

FIG. 10 is a waveform diagram illustrating a fourth determining unit according to the first embodiment of the present invention.

FIG. 11 is a flowchart showing the operation of the three-phase watt-hour meter for determining an incorrect connection in the first embodiment of the present invention.

FIG. 12 is a connection diagram of the three-phase watt-hour meter according to Embodiment 1 of the present invention in a case where incorrect connection is made;

FIG. 13 is a vector diagram of a line voltage and a load current when the power factor is 1 in FIG.

FIG. 14 is a block diagram showing a configuration of a conventional three-phase power measuring device.

[Explanation of symbols]

1, 2, 3 distribution line, 4 three-phase watt-hour meter, 5
1 side transformer, 6 3 side transformer, 7 1 side current transformer, 8 3 side current transformer, 9 ground point, 1
11 1 side current conversion circuit (current conversion means), 12 3 side current conversion circuit (current conversion means), 13 1 side voltage conversion circuit (voltage conversion means), 14 3 side voltage conversion circuit (voltage conversion means), 15 multiplication Circuit (multiplication means), 16
CPU, 17 display circuit (display means), 18
A first timer, 19 a second timer,
22 Power supply line (connection line).

Claims (2)

[Claims] 1. A three-phase power measurement system comprising: introduction means for introducing a line voltage and a load current of a distribution line via a connection line; and multiplication means for multiplying the introduced line voltage and the load current to obtain an integration result. A three-phase watt-hour meter comprising: an introduction unit; the multiplication unit; and an integration unit for integrating the multiplication result of the multiplication unit to obtain an integrated power. A three-phase power meter and a three-phase watt-hour meter each provided with a connection state determining means for determining whether or not the connection state of the connection line is correct based on the result. 2. A three-phase power measurement system comprising: introduction means for introducing a line voltage and a load current of a distribution line via a connection line; and multiplication means for multiplying the introduced line voltage and the load current to obtain a multiplication result. A three-phase power measuring device connection state determination method for determining the connection state of the device, and a three-phase power-measuring device including the introduction means, the multiplication means, and integration means for integrating the multiplication results of the multiplication means to obtain integrated power. In the connection state determination method for a three-phase watt-hour meter for determining a connection state of a watt-hour meter, the three-phase power for determining whether the connection state of the connection line is correct or not based on the introduced line voltage, load current, and the multiplication result. A method for determining the connection state of a measuring instrument and a three-phase watt-hour meter.