JPH0465347B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electronic power measuring device that measures active energy and reactive energy.

[Technical background of the invention]

Conventionally, this type of energy is measured using separate active energy meters and reactive energy meters. As shown in Figure 1, the active energy meter uses pulse width modulation to create a pulse width duty cycle signal by pulse width modulating a signal e _v that is proportional to the load voltage of the feeder line taken out by a voltage transformer 1. A current-voltage conversion element 4 that converts a signal e _i that is proportional to the current consumption of the power supply line taken out by the current transformer 3 into a voltage signal.
and a time division multiplier circuit 5 which performs time division multiplication by taking in a voltage signal e _i proportional to the consumed current while selectively turning on and off the analog switch according to the pulse width duty cycle signal, and the output of this circuit 5. A V-P conversion circuit 7 integrates the voltage in an integrating circuit 6 and converts it into a voltage, and then converts it into a pulse frequency.
and a display section 9 that divides this pulse frequency by a frequency dividing circuit 8 and displays it as an effective amount of power.

On the other hand, in the reactive energy meter, as shown in FIG. The configuration is such that the amount of reactive power can be measured by shifting the phase difference between the signals e _v and e _i , which are proportional to the voltage and current consumption, respectively, by π/2. In the figure, 12 is a display unit that displays the amount of reactive power.

[Problems with background technology]

However, with the above-mentioned power measurement means, active energy is measured with an active energy meter, and reactive energy is measured with a reactive energy meter that is completely different from the active energy meter, so both It is extremely inconvenient to handle when measuring electric energy, and when installed on a power monitoring panel, the scale of the installation becomes large. Furthermore, it is necessary to make electrical adjustments for each electric energy meter, which requires a lot of adjustment work. There is a problem of increasing

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and uses a high-speed multiple phase shift time division method to enable measurement of active and reactive power amounts with one time division multiplier circuit, thereby reducing the number of parts and adjustment man-hours. The present invention also aims to provide an electronic power measuring device that is highly accurate and reliable.

[Summary of the invention]

The present invention provides a time-division pulse divider and controls the first switch circuit with high-speed time-division pulses outputted from the divider to generate a signal proportional to the load voltage of the power supply line and the phase of this signal by π/2. A pulse width duty modulator is used to obtain active power and reactive power by alternately introducing shifted signals into a pulse width modulation circuit.
A cycle signal is created, and a signal proportional to the current consumption of the power supply line is captured using this pulse width duty cycle signal to perform a multiplication operation, and the multiplication result is transmitted to two sets of second
This configuration controls the switch circuit to display active power and reactive power separately.

[Embodiments of the invention]

FIG. 3 is a diagram showing an embodiment of the power measuring device according to the present invention. In the figure, 21 is an instrument transformer that takes out a signal e _v proportional to the load voltage of the power supply line, and this transformer 21 and the pulse width modulation circuit 2
A first switch circuit S1 having an electrical switching section S which performs mutually exclusive operation is interposed between the switching section and the transformer 21, and a shifter having a phase shift of π/2 between the switching section and the transformer 21 is interposed between the switching section and the transformer 21. A phase circuit 23 is provided. Therefore, with the above configuration, a first switch circuit S1 with a signal e _V proportional to the load voltage of the feeder line and a signal e _v ' which is obtained by shifting the phase of this signal by π/2 is created.
The signals are alternately taken in and introduced into the pulse width modulation circuit 22, where the pulse width is modulated by a signal introduced via the switch circuit S1 to create a pulse width duty cycle signal. Reference numeral 24 denotes a time-division pulse distributor, which generates high-speed time-division pulses based on, for example, the clock signal output from the crystal oscillator 25, and distributes the pulses to the first switch circuit S1 and the second switch circuit S, which will be described later.
It has the function of providing 2. 26 is an instrument current transformer that takes out a signal proportional to the current consumption of the power supply line, and the signal obtained here is sent to the current-voltage conversion element 2.
7, it is converted into a voltage signal e _i and introduced into the subsequent time division multiplication circuit 28. It is composed of the time division multiplication circuit 28, analog switches, etc., and selectively turns on and off the analog switches using the pulse width duty cycle signal output from the pulse width modulation circuit 23.
It performs off control, takes in the voltage signal e _i , and performs multiplication operations of e _v ·e _i and e _v ′·e _i . Furthermore, a second switch circuit S2 is connected to the output side of the time division multiplier circuit 28;
2 is an electrical switching unit S that performs a mutually mutually exclusive operation;
S, S, S ^S , one end side of one electrical switching section S, ^S are commonly connected to each other to form a time division multiplier circuit 2.
8 and one end side of the other electrical switching section S is also commonly connected to one output end of the time division multiplier circuit 2.
8, respectively. and an electrical switching section S of the second switch circuit S2,
An integrating circuit 29 for converting the multiplication result of the active power outputted from the time division multiplication circuit 28 into a voltage signal is connected to the other output terminal of the S, and an electrical switching section,
An integrating circuit 30 is connected between the other output terminals of S. Similarly, an integrating circuit 30 that converts the multiplication result of the reactive power outputted from the time division multiplication circuit 28 into a voltage signal is connected. In the figure, 31 and 32 are V-P conversion circuits that convert a voltage signal into a pulse frequency, 33 and 34 are frequency dividing circuits, and 3
5 is an active power amount display unit that displays active power amount, 3
6 is a reactive power amount display section that displays the amount of reactive power.

Next, the operation of the device configured as above will be explained. The signal e _v proportional to the load voltage of the feeder line taken out by the instrument transformer 21 is branched into two branches, one of which is directly introduced to the switching section S side of the first switch circuit S1, and the other is phase-shifted. The circuit 23 delays the phase by π/2 and introduces the signal into the other opening/closing section. Here, each opening/closing section S of the first switch circuit S1 is alternately turned on and off by the high-speed time division pulse from the time division pulse distributor 24, so that The signal e _v and the signal e _v ' with a phase shift delay of π/2 are alternately supplied to the pulse width modulation circuit 22. As a result, the pulse width modulation circuit 22 first performs pulse width modulation using the signal e _v to create a pulse width duty cycle signal, introduces this into the time division multiplication circuit 28, and subsequently uses the signal e _v ' to generate a pulse width duty cycle signal. Similarly, a pulse width duty cycle signal is generated by pulse width modulation and introduced into the time division multiplication circuit 28. Here, the time division multiplication circuit 28 takes in a signal e i which is a pulse width duty cycle signal corresponding to the signal e _{v and} is proportional to the current consumption of the power supply line, and performs time division multiplication of e _v ·e _i . At this time, since the opening/closing parts S and S of the second switch circuit S2 are closed, the multiplication result of the time division multiplication circuit 28 is converted into a voltage signal by the integrating circuit 29 through the opening and closing parts S and S. , is converted into a pulse frequency by the V-P conversion circuit 31, and the active power amount is displayed on the display section 35. Next, when the pulse width duty cycle signal corresponding to the signal e _v ' is introduced into the time division multiplier circuit 28, a signal e _i proportional to the current consumption of the feeder line is similarly introduced.
Performs the multiplication e _v ′・e _i and outputs the multiplication result.
At this time, the opening/closing section is closed by the high-speed divided pulses of the time division pulse distributor 24, so the multiplication output of the time division multiplication circuit 28 is sent to the integrating circuit 30 through the opening/closing section S. is converted into a voltage signal here. And this voltage signal is V
The -P conversion circuit 32 converts the signal into a pulse frequency, and the signal is further frequency-divided to display the amount of reactive power on the display section 36. To explain the above operating state with reference to FIG. 4, first, the switch circuit S
1 closes and the signal e _v is introduced into the pulse width modulation circuit 22, and a pulse width duty cycle signal is obtained, for example, e _v · e _i between points a and c in the figure.
Performs the multiplication of

Next, the opening/closing part S of the switch circuit S1 is closed, and the signal e _v ' enters the pulse width modulation circuit 22, and a pulse width duty cycle signal is also obtained, and e _v '. Perform multiplication of e _i . This operation is repeated at high speed using high-speed time division pulses. Here, e _v . Since e _i is a signal proportional to the active power, if this signal is converted into a pulse frequency and then divided appropriately, the active power amount can be displayed on the display section 35. The reactive power amount can also be displayed on the display section 36 by performing signal processing.

Next, FIG. 5 is a diagram in which the device of the present invention is applied to a three-phase, three-wire power device. That is, this device includes two sets of potential transformers 21a, 21b, phase shift circuits 23a, 23b, and switch circuits S1a, 21b, respectively.
S1b, the pulse width modulation circuit 22 generates a pulse width duty cycle signal by introducing signals proportional to the load voltages of a plurality of power supply lines in the order of e _va , e _va ′, e _vb , and e _vb ′. , this signal is sequentially supplied to the time division multiplication circuit 28. At this time, switch S3,
S4 is also controlled on and off in a predetermined order. As a result, in the time division multiplication circuit 28, based on the output of the pulse width modulation circuit 22, e _va ·e _ia , e _va ′·e _ia ,
The multiplications e _vb ·e _ib and e _vb ′·e _ib are performed to obtain the active power on the 1 side, the reactive power on the → side, the active power on the → side, and the reactive power on the → side.

Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications.

〔Effect of the invention〕

As described in detail above, according to the present invention, a signal proportional to the load voltage and a signal obtained by delaying the phase of this signal by π/2 are captured using a high-speed time division method to create a pulse width duty cycle signal. Since the active power and reactive power are obtained by multiplying the signal by a signal proportional to the current consumption, almost one functional component of the watt-hour meter, excluding the display system, can be used to calculate the active power and reactive power. can be measured. This means that
By significantly reducing the number of parts, not only can costs be reduced, but the scale of installation can be reduced when installing on a power monitoring panel, etc. Moreover, adjustment work is essentially sufficient for one power meter, and the same Since a signal proportional to the load voltage and current consumption is extracted from the transformer and current transformer, it is possible to provide an electronic power measuring device that has the same error range and is highly reliable. .

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional active watt-hour meter, FIG. 2 is a configuration diagram of a conventional reactive watt-hour meter, and FIG. 3 is a configuration diagram showing an embodiment of an electronic power measurement device according to the present invention. FIG. 4 is a diagram showing the multiplication timing of this device,
FIG. 5 is a diagram showing the configuration of another invention. 22...Pulse width modulation circuit, 23, 23a, 2
3b... Phase shift circuit, 24... Time division pulse distributor, 28... Time division multiplication circuit, S1 to S4... Switch circuit, 29, 30... Integration circuit, 35, 3
6...Display section.

Claims (1)

[Claims] 1. A time division pulse distributor that outputs a high-speed time division pulse signal, a first signal proportional to the load voltage of a power supply line, and a phase shift of this first signal by (π/2). means for alternately capturing the second signal obtained by the high-speed time-division pulse signal; A pulse width modulation circuit generates a pulse width duty cycle signal, and a pulse width duty cycle signal output from the pulse width modulation circuit receives a signal proportional to the consumption current flowing through the power supply line. a time-division multiplication circuit that selectively takes in proportional signals and performs time-division multiplication, and after alternately taking in the first and second multiplication outputs output from this time-division multiplication circuit using the high-speed time-division pulse signal; What is claimed is: 1. An electronic power measuring device comprising a plurality of power amount display means for distinguishing and displaying active power amount and reactive power amount by converting them into pulse frequencies. 2. A time division pulse distributor that outputs a high-speed time division pulse signal, a plurality of first signals proportional to the load voltage of a plurality of power supply lines, and a phase shift of these first signals by (π/2). means for sequentially capturing a plurality of second signals in a predetermined order by the high-speed time-division pulse signal, and a pulse width by the respective plurality of first and second signals captured by these means a pulse width modulation circuit that modulates to create first and second pulse width duty cycle signals; and a pulse width modulation circuit that receives a plurality of signals proportional to the current consumption flowing through each of the feed lines and outputs pulses from the pulse width modulation circuit. a time division multiplication circuit that takes in a plurality of signals proportional to the current consumption in a predetermined order according to a width date cycle signal and performs time division multiplication; and a first and second signal outputted from the time division multiplication circuit. The electronic device is characterized by comprising a plurality of power amount display means that alternately captures the multiplication output using the high-speed time-division pulse signal, converts it into a pulse frequency, and displays the active power amount and the reactive power amount separately. type power measurement device.