JPH10339747A - Indicator gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an indicator gauge with which an error caused by the dispersion of component performance can be easily adjusted and inexpensively corrected. SOLUTION: Concerning the indicator gauge which is attached to a power reception panel or a power distribution panel for measuring various kinds of electric energy, this device is provided with a signal converting part 8 for converting inputted 1st and 2nd currents and 1st and 2nd voltages to proportional voltage signals, measuring part 10 for measuring 1st and 2nd power values from these converted signals, phase error measuring part 16 for measuring a phase error from a reference value by comparing the ratio of 1st and 2nd power values measured by the measuring part 10 with the ratio of inputted 1st and 2nd power values (reference values), and phase error correcting part 16 for shifting the measurement starting time of either current or voltage at the measuring part 10 at least based oh the time difference provided by the time conversion of this phase error.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indicating instrument for measuring an electric quantity such as current, voltage, power, reactive power, power factor, and frequency.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram of a measuring circuit portion of a conventional indicating instrument equipped with an electric circuit. In the figure,
1, 2, and 3 represent the R phase and S of the electric circuit to be measured, respectively.
Phase, T phase. Reference numeral 4 denotes an instrument transformer (hereinafter, referred to as VT) that reduces the voltage between the R and S phases, and reference numeral 5 denotes a VT that reduces the voltage between the S and T phases. Reference numerals 6 and 7 denote instrument current transformers (hereinafter, referred to as CTs) that transform R-phase and T-phase currents, respectively. Reference numeral 8 denotes a signal converter for converting the signals corresponding to the VTs 4 and 5 and the CTs 6 and 7 into voltage signals proportional to the signals. Reference numeral 9 denotes a multiplexer, which selects an output signal of the signal conversion unit 8 according to a control signal of the measurement control unit 12. 10
Is a measurement unit including an A / D conversion unit 11 and a calculation unit. The measurement unit converts the output signal of the signal conversion unit 8 selected by the multiplexer 9 into a digital signal, and measures the quantity of electricity by calculation. These measurement values are stored in the storage unit 13 for each measurement value for each measurement item. 14 is a display for displaying each measured value, and 15 is a display switching unit for switching the measured value to be displayed.

[0003]

The conventional indicating instrument is constructed as described above. The signals corresponding to VT4 and VT are the voltage values, the signals corresponding to CT6 and CT are the current values and VT.
From the signals corresponding to 4 and 5, and the signals corresponding to CTs 6 and 7, the calculation unit of the measurement unit 10 measures an electric quantity such as a power value, a reactive power value, and a power factor value. Of these, power values,
The amount of electricity of the reactive power value and the power factor value is determined by the phase error between the signals corresponding to VT4 and VT4 and the signals corresponding to CT6 and CT7.
The accuracy of the measurement is affected. The conventional indicating instrument does not have a phase error correcting function, but has a function such as zero level adjustment for installation adjustment of the indicating instrument.
Further, in order to increase the accuracy of the measured electric quantity, it is necessary to select a component that hardly causes a phase error.

In other words, the conventional countermeasure against the phase error of the indicating instrument is implemented by selecting parts, and does not adjust (correct) the phase error caused by the variation of the parts. Therefore, in the conventional indicating instrument, if there is a variation in the selected components, the electric quantity is measured reflecting the phase error caused by the variation of the parts, and there is a problem that the precision of the electric quantity measurement is poor. This phase error is V
T4, 5, CT6, 7, signal converter 8, A / D converter 1
1, for example, in the signal conversion unit 8,
The phase error caused by the transformer VT, the current transformer CT, and the capacitor, which converts the level into a minute signal level that can be input to the electronic circuit, is particularly affected.

The present invention has been made to solve the above problems, and has as its object to provide an indicating instrument capable of correcting a phase error generated due to a variation in parts and accurately measuring an electric quantity.

[0006]

SUMMARY OF THE INVENTION An indicating instrument according to the present invention, which is attached to a power receiving panel, a power distribution panel, or the like to measure various amounts of electricity, converts an input current and voltage into a voltage signal proportional to the current and voltage. A signal conversion unit, a measurement unit for measuring a power value from the converted signal, and a phase error from the reference value by comparing the power value measured by the measurement unit with an input power value (reference value). And a phase error correction unit that shifts the measurement start time of at least one of the current and the voltage in the measurement unit based on the time difference obtained by performing time conversion on the phase error. It is provided.

[0007] Further, in a device for measuring various amounts of electricity attached to a power receiving panel, a power distribution panel, or the like, the first and second input signals are used.
A signal converter for converting the current and the first and second voltages into voltage signals proportional thereto, a measuring unit for measuring first and second power values from the converted signals, and an upper front measuring unit A phase error measuring unit that compares the ratio of the first and second power values measured in the above with the ratio of the input first and second power values (reference values) and measures the phase error from the reference value. And a phase error correction unit that shifts at least one of the measurement start time of the current and the voltage in the measurement unit based on a time difference obtained by performing time conversion on the phase error.

[0008] The phase error measuring section calculates the R-phase power value (V
₁₂ · I ₁ ) and the T-phase power value (V ₃₂ · I ₃ ) are within a predetermined range (equal V ₁₂ · I ₁ = V ₃₂ · I ₃ ), the first power value and the second power value And a phase error from a reference value is measured.

The measuring unit, the phase error measuring unit, and the phase error correcting unit are configured by a microcomputer program, and determine the phase error with reference to a table having a relationship between phase and time provided in advance. Time conversion is used.

[0010] Further, in a device which is attached to a power receiving panel, a power distribution panel, or the like to measure various electric quantities, a signal converting section for converting an input current and voltage into a voltage signal proportional thereto, A measuring unit for measuring the value, and at least one of the current and the voltage in the measuring unit until the electric power value measured by the measuring unit and the input electric power value (reference value) fall within a predetermined range (match). A phase error correction unit that corrects a phase error by changing one of the measurement start times by a minute time.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a circuit block diagram showing Embodiment 1 of the present invention. In the figure, 1, 2, and 3 denote R, S, and T phases of an electric circuit to be measured, respectively, and 4 denotes an instrument transformer (hereinafter referred to as a VT) that steps down a voltage between the R and S phases. Are VTs that reduce the voltage between the S and T phases,
Is a current transformer for an instrument (hereinafter referred to as CT) that transforms R-phase and T-phase currents. 8 is the above VT4, 5 and C
A signal converter 9 for converting the signals corresponding to T6 and T7 into a voltage signal proportional thereto is a multiplexer, and selects an output signal of the signal converter 8 according to a control signal of the measurement controller 12. Reference numeral 10 denotes a measurement unit including an A / D conversion unit 11 and a calculation unit. The measurement unit 10 converts the output signal of the signal conversion unit 8 selected by the multiplexer 9 into a digital signal, and measures the quantity of electricity by the calculation unit of the measurement unit 10. I do. These measurement values are stored in the storage unit 13 for each measurement value for each measurement item. 14 is a display for displaying each measured value, and 15 is a display switching unit for switching the displayed measured value. 1
Reference numeral 6 denotes a phase error measurement / correction unit for the signals corresponding to the VTs 4 and 5 and the signals corresponding to the CTs 6 and 7 and includes an arithmetic processing unit 16a, a memory unit 16b, and a data table 16c.

FIG. 2 is a flowchart for phase error correction according to the first embodiment. First, in step 101 of the flowchart, a first electric quantity having a power of 60 Hz, a power factor of 1, 110 V, and 500 W is input to electric circuits 1, 2, and 3 from a power supply (not shown). Steps 102 and 103
In, signals corresponding to VTs 4 and 5 and signals corresponding to CTs 6 and 7 are A / D-converted at a fixed sampling interval, and the respective A / D-converted data is stored in the storage unit 13. A / D measured in steps 102 and 103 in step 104
A first power value A is obtained from the converted data.

In step 105, a 60 Hz power factor LEAD is applied to the electric circuits 1, 2, and 3 by a power supply (not shown).
(Advance) A second electric quantity of 0.5, 110 V, and 500 W is input. In steps 106 to 108, the same processing as in steps 102 to 104 is performed, and the second power value B
Ask for. In step 109, step 104,
The correction coefficient K = B / (2 ×
Find A).

Here, FIG. 4 shows a vector diagram when power is obtained by the two-power method. In the three-phase balanced circuit, in the two-power method, the power value can be obtained by the sum of the product of the R-phase-S-phase voltage and the R-phase current and the product of the S-phase-T-phase voltage and the T-phase current. The power value A when the power factor is 1 is as follows. _{A = V 12 · I 1 ·} cos (30 ° _{+ θ 1) + V 32 ·} I 3 · cos (-30 ° + θ ₁₎ ··· (501) where, V ₁₂ is R Ai S interphase voltage, I ₁ Is the R-phase current, V
₃₂ indicates a voltage between the T phase and the S phase, I ₃ indicates a T phase current, and θ ₁ indicates a phase error (angle).

The power value B when the power factor LEAD is 0.5 is as follows. _{B = V 12 · 2I 1 ·} cos (30 ° + theta ₁ +60 _{°) + V 32 · 2I 3 ·} cos (-30 ° + theta ₁ +60 °) (502) where the power value A and the reference value of the formula 501 difference although the error power due to phase error, may contain errors to a value such as _{V 12, I 1, V 32} , I 3 in the formula 501, i.e., other than the error due theta ₁ and the 500W of May contain things. Therefore, the correction coefficient K is obtained from Expressions 501 and 502.
(= B / (2 × A)), V ₁₂ , I ₁ , V ₃₂ , I ₃
Is a formula that depends only on θ ₁ and can be adjusted more precisely. Therefore, the phase error can be detected by obtaining the correction coefficient K by the following equation 503. K = B / 2A = [cos (90 ° + θ ₁ ) + cos (30 ° + θ ₁ )] / [cos (30 ° + θ ₁ ) + cos (−30 ° + θ ₁ )] = cos (60 ° + θ ₁ ) / cos θ ≒ cos (60 ° + θ ₁ ) (503) (from cos θ ≒ 1)

The following equation 504 is an equation for converting the phase error angle θ ₁ into time. If one cycle time of the AC waveform is T, the delay time T _D (μsec) can be expressed as in equation 504. the formula 503 and formula 504, can determine the delay time T _D represented by the formula 505 from the correction coefficient K. _{T D = (θ 1/360} °) × (1 / T) × 10 -3 ··· (504) (T = 1/60 when 60Hz) _{Accordingly, T D = (16666 / 2π} ) × (cos - in ^{1 K + π / 3) ···} (505) step 110 obtains a delay time T _D corresponding to the correction coefficient K from the memory table 16c in the memory section 16b of the phase error measurement and correction unit 16 (see FIG. 3), step 11
1 to determine the delay time T _D , the phase error measurement / correction unit 1
The memory section 16b of the 6 stores the delay time T _D.

The delay time T _D is a time for delaying (advancing) the start of sampling. If there is no cause of the phase error in the circuit, the signals corresponding to VT4,5, CT6,
7 may be A / D sampled at the same timing, but if a phase error occurs in the circuit,
It is necessary to delay sampling of the signal corresponding to either the signal corresponding to T4,5 or the signal corresponding to CT6,7.

The operation of the phase correction is completed as described above. Next, a flowchart in the operating state is shown below. Step 1
13a sets the timer A / D delay time T _D when sampling the signal corresponding to VT4,5, set the delay time T _D when step 113b is for sampling a signal corresponding to CT6,7 timer It intended to, and sets the T _D stored in step 112 113a, to one of the timer 113b, the remaining timer is set to zero. Here, the case where the sampling of the signals corresponding to CT6 and CT7 is delayed is described.
The timer set value is set to 0 for A / D of 4 and 5.

At steps 114a and 114b, sampling is started after each timer time elapses. At steps 115a and 115b, A / D is performed at a constant sampling interval.
The conversion data is stored in the storage unit 13. Step 116
The values of various electric quantities are obtained from the A / D conversion data measured at 115a and 115b. As described above, the steps 113 to 116 are continuously and repeatedly performed in the operating state, and the measurement data is displayed on the display 14 as necessary.

As described above, the correction coefficient K is obtained from the power values under two different conditions, the delay time T _D is obtained based on the correction coefficient K, and the sampling time is delayed by the delay time T _D. The error due to the variation of the parts can be corrected by the automatic calculation based on the calculation of the microcomputer, so that the quantity of electricity can be measured accurately without complicating the operation. Further, since the delay time T _D can be obtained from the table on the memory corresponding to the correction coefficient K, the delay time T _D can be obtained in a short time.

Embodiment 2 FIG. FIG. 5 is a flowchart for phase error correction of the indicating instrument according to the second embodiment. The circuit configuration is the same as in the first embodiment. In the flowchart of FIG. 5, steps 201 to 209, 211
Steps 216 to 216 correspond to steps 101 to 109, 1 in the first embodiment.
Same as 11 to 116.

In the second embodiment, in step 210, as a method of obtaining the delay time T _D ,
The delay time T _D is obtained by Expression 505 using the power values A and B obtained in Steps 4 and 208. With this configuration, in addition to the effects of the first embodiment, a data table is not required, and the memory capacity can be reduced.

Embodiment 3 FIG. FIG. 6 is a flowchart for phase error correction of the indicating instrument according to the third embodiment. The circuit configuration is the same as in the first embodiment. In the flowchart of FIG. 6, steps 301 to 303, 306
311 are steps 101 to 103 of the first embodiment,
Same as 11 to 116. In the third embodiment,
The case where the amount of electricity is a reactive power value will be described.
It goes without saying that the same applies to the case where the power value is obtained instead of the reactive power value as in the first embodiment.

In the third embodiment, steps 302 and 30
From the A / D conversion data measured in step 3,
In step 4, the reactive power value A is obtained. The reactive power value A is given by Equation 5
01, it can be obtained by the following equation 601. _{A = V 12 · I 1 ·} sin (30 ° _{+ θ 1) + V 32 ·} I 3 · sin (-30 ° + θ ₁₎ ··· (601) wherein, R-phase power value (V ₁₂ · I ₁₎ T-phase power value (V ₃₂
I ₃ ) is within a predetermined range (equal V ₁₂ · I ₁ =
V ₃₂ · I ₃ ). Then, when it is within the predetermined range, V ₁₂ · I ₁ = V ₃₂ · I ₃ can be satisfied. Therefore, rearranging the expression 601 as V ₁₂ · I ₁ = V ₃₂ · I ₃ = V · I gives the following expression 602 become that way. A = VI · [sin (30 ° + θ ₁ ) + sin (−30 ° + θ ₁ )] = C · sin θ ₁ (602)

Here, when the power factor is 1, the reactive power becomes 0, but it becomes an error due to the phase error (angle) θ ₁ . Therefore,
The delay time T _D can be obtained by using the Sin θ ₁ part of the expression 601 as the correction coefficient K ₁ . T _D = (θ _1/360 °) × (1 / T) × 10 -3 (T = 1/60 when 60Hz) _{Accordingly, T D = (16666 / 2π} ) × sin -1 K 1 phase error theta ₁ and since the relationship between the correction coefficient K ₁ is the same as that of the first embodiment as shown in FIG. 7, it is possible to obtain T _D by the correction coefficient K _1. In step 305, the delay time T corresponding to the reactive power value A in step 304
_D is obtained and phase error correction is performed.

[0026] Here, when obtaining the T _D, delimiting the correction coefficient K ₁ at regular intervals the width, to the data data table of such as shown in FIG. 7 an arithmetic expression and the T _D value within that interval to a fixed value Can be. T separated by a constant interval of the correction factor K _{1
Even if the D} value is fixed, the influence on the error is small if the fixed interval width is reduced. By a data table, it is possible to determine immediately the T _D value from the correction factor K _1, it is not necessary to the circuit constituting the function of arithmetic processing can be achieved cost, faster.

The third embodiment, since the configuration as described above, in addition to the effect of the first embodiment, will be requires only one input conditions for determining the delay time T _D, a simple configuration , And can quickly respond to the phase error. In a circuit in which the state of the three-phase balanced circuit is stable and V ₁₂ · I ₁ = V ₃₂ · I ₃ is satisfied in a steady state, the R-phase power value (V ₁₂ · I ₁ ) and the T-phase power value (V ₃₂ · I ₃ ) is within a predetermined range (equal V ₁₂ · I ₃ )
I ₁ = V ₃₂ · I ₃ )
It is useful to determine the delay time T _D according to H.02.
In this case, since only one input condition is required for determining the delay time T _D , the configuration can be simplified and the phase error can be quickly dealt with.

Embodiment 4 FIG. 8 is a flowchart for phase error correction of the indicating instrument according to the fourth embodiment. The circuit configuration is the same as in the first embodiment. In the flowchart of FIG. 8, steps 401 to 403, 406
To 411 are steps 101 to 103 of the first embodiment,
Same as 11 to 116.

In the fourth embodiment, steps 402 and 40
Based on the A / D conversion data measured in step 3,
At 04, a reactive power value A is obtained. In step 405, the delay time T _D is obtained by the arithmetic expression 602 using the reactive power value of step 404 as input data, and the phase error is corrected. With this configuration, in addition to the effects of the first embodiment, a data table is not required, and the memory capacity can be reduced.

Embodiment 5 FIG. 9 is a flowchart for phase error correction of the indicating instrument according to the fifth embodiment. The circuit configuration is the same as in the first embodiment. In the flowchart of FIG. 9, steps 501, 511-514
Are the same as 101, 113 to 116 in the first embodiment.

In steps 502a and 502b, first, a timer is set with the delay time T _D = 0. In steps 503a, 503b, 504a, and 504b, V
The signals corresponding to T4 and T5 and the signals corresponding to CT6 and CT7 are sampled, and the reactive power A is obtained in step 505. At step 506, it is determined whether reactive power A = 0 at step 505, and if it is not 0 (predetermined range), re-measurement is performed at step 507, and at step 508, reactive power A is LEAD (lead) or LAG (lag).
Is determined.

If LEAD, the C value is incremented by 1, and steps 502 to 506 are performed again. In the case of LAG,
The B value is incremented by 1, and steps 502 to 506 are performed again. Step 50 until the reactive power A = 0 in step 505
Repeatedly performed 2-507, at step 510, the T _D when it becomes 0 is determined as A / D delay time, and stores this T _D in the memory of the phase error detecting and correcting unit 16.
And performs phase error correction by an A / D delay time T _D of the step 510.

In the fifth embodiment, the sampling timing is slightly changed until the phase error falls within a predetermined range because of the configuration described above, and only one input condition is required for determining the delay time T _D. Well, it can be corrected more easily.

In the above-described embodiment, the case where the delay time T _D is calculated by the microcomputer has been described. However, this is based on the premise that the indicating instrument is constructed simply and inexpensively. It is also possible to configure by an analog circuit.

[0035]

As described above, according to the present invention, an error due to a variation in parts can be corrected by an automatic calculation by a microcomputer, so that the operation can be accurately performed without complicating the operation. It is possible to make measurements.

Further, it is possible to determine in response to the correction coefficient a delay time T _D from the table in the memory, it is possible to obtain a short time delay time T _D.

In addition, the correction can be easily performed by using only one input condition for determining the delay time.

Further, a delay time T _D is obtained by an arithmetic expression,
When the configuration is such that phase error correction is performed, a data table is not required, and the memory capacity can be reduced.

Further, the sampling timing, by the phase error so as to minimal change until within a predetermined range, well one input condition is when determining the delay time T _D, the more easily an error correction can do.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an indicating instrument according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart illustrating the operation of the first embodiment.

FIG. 3 is a diagram illustrating a data table according to the first embodiment;

FIG. 4 is a vector diagram illustrating an arithmetic expression according to the first embodiment.

FIG. 5 is a flowchart illustrating an operation of the indicating instrument according to Embodiment 2 of the present invention.

FIG. 6 is a flowchart illustrating an operation of the indicating instrument according to Embodiment 3 of the present invention.

FIG. 7 is a diagram showing a data table according to the third embodiment.

FIG. 8 is a flowchart illustrating an operation of the indicating instrument according to Embodiment 4 of the present invention.

FIG. 9 is a flowchart illustrating the operation of the indicating instrument according to Embodiment 5 of the present invention.

FIG. 10 is a circuit block diagram showing a conventional indicating instrument.

[Explanation of symbols]

1 R phase of an electric circuit, 2 phase of an electric circuit, 3 phase of an electric circuit, 4 and 5 instrument transformers, 6 and 7 instrument current transformers, 8 signal conversion units, 9 multiplexers, 10 measurement units, 11 A / D conversion unit, 12 Measurement control unit, 13 Measurement value storage unit, 14 Display unit, 15 Display switching unit, 16
Phase error measurement / correction unit, 16a arithmetic processing unit, 16b
Memory unit, 16c data table.

Claims (5)

[Claims] 1. An indicating instrument attached to a power receiving panel, a switchboard, or the like, for measuring various electric quantities, a signal converting section for converting an input current and voltage into a voltage signal proportional thereto, and A measuring unit for measuring a power value; a phase error measuring unit for comparing a power value measured by the measuring unit with an input power value (reference value) to measure a phase error from the reference value; An indicating instrument comprising: a phase error correction unit that shifts at least one of the current and voltage measurement start times in the measurement unit based on a time difference obtained by converting the error into time. 2. An indicating instrument attached to a power receiving panel, a power distribution panel, or the like, for measuring various amounts of electricity.
A signal conversion unit that converts the current and the first and second voltages into voltage signals proportional to the current, a measurement unit that measures first and second power values from the converted signal, A phase error measuring unit that compares a ratio of the measured first and second power values to a ratio of the input first and second power values (reference values) and measures a phase error from the reference value; A phase error correction unit for shifting a measurement start time of at least one of a current and a voltage in the measurement unit based on a time difference obtained by performing time conversion on the phase error. Instrument. 3. The phase error measuring section calculates an R-phase power value (V ₁₂ ···
2. The apparatus according to claim 1, wherein when the magnitude of I ₁ ) and the T-phase power value (V ₃₂ · I ₃ ) are within a predetermined range, a phase error from a reference value is measured. Indicating instrument. 4. The measuring unit, the phase error measuring unit, and the phase error correcting unit are configured by a microcomputer program, and determine a phase error with reference to a table having a relationship between phase and time provided in advance. The indicating instrument according to any one of claims 1 to 3, wherein time conversion is performed. 5. An indicating instrument attached to a power receiving panel, a power distribution panel, or the like for measuring various electric quantities, a signal converting section for converting an input current and voltage into a voltage signal proportional thereto, and A measuring unit for measuring the power value, and at least one of the current and the voltage at the measuring unit until the power value measured by the measuring unit and the input power value (reference value) fall within a predetermined range. An indicating instrument comprising: a phase error correction unit that corrects a phase error by changing a measurement start time by a minute time.