JP3561187B2 - Inductive watt-hour meter with average power measurement function - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inductive power amount that detects the power consumption of a circuit under measurement by a mechanical rotor, converts the detected power consumption into an electric pulse, and electronically calculates the power consumption of the circuit under test. About the total.
[0002]
[Prior art]
Conventionally, in this type of hybrid inductive watt-hour meter, the voltage of the circuit under test is detected by a voltage coil and the current of the circuit under test is detected by a current coil, and the voltage is induced by the electromagnetic field generated by the voltage coil and the current coil. And the mechanical rotor rotates. The rotation of the rotor is converted into electric pulses by an optical sensor, and the number of pulses is counted by an electronic circuit using a microcomputer. The number of electric pulses to be converted is the number of pulses according to the power consumption since the rotation speed of the rotor is in accordance with the power consumption of the circuit to be measured. Accordingly, the power consumption of the circuit under measurement is calculated as an integrated value from the integrated count value of the pulse number, and the calculated power amount is displayed on the liquid crystal display.
[0003]
[Problems to be solved by the invention]
However, the above-mentioned conventional inductive watt-hour meter is used to measure only the integrated power amount, and cannot measure the short-time average power used in a short time in the circuit to be measured. Therefore, in order to measure the short-time average power, conventionally, a voltage measurement sensor such as a VT (voltage transformer), a current measurement sensor such as a CT (current transformer), and power detected by each sensor are used. A dedicated measuring instrument for visual display is separately prepared, and these devices are often installed in an inductive watt-hour meter to measure the average power in a short time.
[0004]
For this reason, when measuring the average power in a short time with a conventional inductive watt-hour meter, the space for installing the voltage and current measurement sensors and the dedicated measuring device is provided for the watt hour meter. Needed separately from space. Since the inductive watt-hour meter is generally installed on the wall of a customer's house, it is difficult to secure a large equipment installation space on the wall of the customer's house. Also, if such equipment is installed on a wall of a customer house occupying a large space, the aesthetic appearance of the house will be impaired. Also, in order to maintain the aesthetics of the house, it is necessary to install equipment that takes into account the aesthetics on the wall.
[0005]
Also, if you just want to measure the short-term average power used in the circuit under test simply as a guide, you will need to install a measuring instrument similar to that used to accurately measure the short-term average power, Get high.
[0006]
[Means for Solving the Problems]
The present invention has been made to solve such a problem, and the magnetic flux generated by combining the current coils of each phase and the inter-phase magnetic flux according to the amount of electric power used by the circuit to be measured distributed by the polyphase distribution system. A rotor that is electromagnetically induced to rotate by a magnetic flux generated by the combination of the voltage coils, a pulse generator that generates a predetermined number of electric pulses per unit power consumption according to the rotation of the rotor, and a pulse generator. Means for calculating an integrated power amount of the circuit to be measured by integrating the number of pulses generated by the means. Pulse counting means for counting the number of pulses generated by the generating means, and calculating short-time average power used by the circuit under test for a predetermined time based on the number of pulses counted by the pulse counting means Characterized by comprising a built-in and the average power calculation unit that.
[0007]
In such a configuration, when power is consumed in the circuit under test distributed in the multi-phase distribution system, the magnetic flux generated by the combination of the current coils of each phase and the voltage coil between the phases are generated according to the amount of power. The rotor is rotated by electromagnetic induction by the magnetic flux generated by the combination, and the number of electric pulses corresponding to the power consumption is generated by the pulse generating means. The number of pulses is integrated by the power amount measuring means, and the integrated power consumption of the circuit to be measured is calculated from the integrated value. The number of pulses generated during a predetermined period of time is counted by the pulse counting unit, and based on the counted value, the average power calculating unit is used by averaging the circuit under test during the predetermined period of time. Calculate the short-term average power. Therefore, the short-time average power of the circuit to be measured is measured by the inductive watt-hour meter alone.
[0008]
Further, according to the present invention, the pulse counting means counts the number of pulses generated by the pulse generating means at regular time intervals, and the average power calculating means is used by averaging the measured circuit at regular time intervals. It is characterized by calculating short-time average power.
[0009]
In such a configuration, the short-time average power used by the circuit under measurement is averaged and calculated repeatedly at regular intervals. Therefore, the short-term average power of the circuit under measurement is grasped in real time at regular intervals.
[0010]
Further, according to the present invention, the average power calculating means distributes the number of pulses counted by the pulse counting means to the predetermined number of pulses generated per unit power consumption by the pulse generating means, a predetermined time, and the circuit to be measured. And calculating the short-time average power used in the circuit to be measured by dividing the product by a product of a coefficient corresponding to the phase of the power distribution system .
[0011]
For the circuit under test distributed by the polyphase distribution method, only the number of electric pulses corresponding to the combined power consumption of each phase can be obtained, but if the average power calculation means is used to calculate the short-time average power in this way, Although accurate average power measurement cannot be performed, average power measurement can be performed as a guide.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of an inductive watt-hour meter with an average power measuring function according to the present invention will be described.
[0013]
FIG. 1 is a block diagram schematically showing a configuration of a hybrid inductive watt-hour meter according to the present embodiment.
[0014]
A hybrid inductive watt-hour meter detects a voltage and a current of a circuit under test of a customer, and generates an electric pulse corresponding to the amount of electric power used, and an electric pulse generated by the power detecting unit. And an arithmetic unit for calculating the integrated power consumption and the short-time average power of the circuit under measurement based on the number.
[0015]
The power detection unit includes a rotator 1, a signal disk 2, and an optical coupling element 3 as main elements. The rotator 1 is guided by an electromagnetic field generated by a voltage coil and a current coil for detecting the voltage and current of the circuit under measurement, and rotates according to the amount of power used. The signal disk 2 is provided on a rotation shaft of the rotor 1 and rotates with the rotation of the rotor 1. The signal disk 2 has a wing portion 2a and a notch portion 2b. The optical coupling element 3 is configured by an optical sensor such as a photo interrupter, and is arranged so that the signal disk 2 rotating in the “U” -shaped valley passes therethrough.
[0016]
The optical coupling element 3 emits a light beam between the U-shaped valleys, and while the light ray is blocked by the wings 2a of the signal disk 2, the optical coupling element 3 outputs a low-level signal. I do. However, while the signal disk 2 rotates and the light beam crosses the notch 2b, the optical coupling element 3 outputs a high-level signal. Therefore, the optical coupling element 3 generates an electric pulse p according to the rotation of the signal disk 2. Since the rotation of the signal disk 2 is synchronized with the rotation of the rotor 1, the number of electric pulses p generated by the optical coupling element 3 is a number corresponding to the power consumption of the circuit under test. The number of electric pulses p generated by the optical coupling element 3 per unit power consumption becomes a predetermined number of pulses according to an instrument constant [pulse / kWh] preset for the inductive watt-hour meter.
[0017]
The arithmetic unit has a CPU (Central Processing Unit) 4 that performs a control operation according to a preset program. The CPU 4 operates by receiving power supply from the power supply circuit 5. The CPU 4 includes a pulse I / F (interface) circuit 6, a power amount measurement counter 7, an average power measurement counter 8, a liquid crystal display 9, a communication function I / F circuit 10, a power failure detection circuit 11, and a nonvolatile memory. 12 are connected. The power input terminal is connected to a protection circuit 13 for protecting an incoming abnormal voltage or the like due to lightning or the like.
[0018]
The integrated value of the electric pulse p input from the optical coupling element 3 via the pulse I / F circuit 6 is counted by the electric energy measurement counter 7. The average power measurement counter 8 constitutes a pulse counting unit that counts the electric pulses p input from the optical coupling element 3 via the pulse I / F circuit 6 at predetermined time intervals. The CPU 4 constitutes an average power calculation means for calculating a short-time average power used in the circuit under measurement for a certain period of time based on the number of pulses counted by the average power measurement counter 8. The liquid crystal display 9 visually displays the integrated power consumption and the short-time average power of the circuit under measurement calculated by the CPU 4 based on the count values of the power amount measurement counter 7 and the average power measurement counter 8. The communication function interface 10 sends the calculated integrated power consumption and short-time average power to an external device.
[0019]
Further, when the power failure is detected by the power failure detection circuit 11, the CPU 4 writes the count value of the power amount measurement counter 7 at that time into the nonvolatile memory 12. Therefore, even if a power failure occurs, the integrated power amount at the time of the power failure is stored and held in the nonvolatile memory 12 until the power is restored.
[0020]
FIG. 2 is a timing chart showing a counting mechanism in the electric energy measurement counter 7 and the average electric power measurement counter 8.
[0021]
When the electric pulse p is generated as shown in FIG. 4B, the electric energy measurement counter 7 sets the count value to 1 each time an edge change of the electric pulse p is detected as shown in FIG. Count up to 2, 3, ... and increase the integrated value over time. The CPU 4 calculates an integrated power consumption W [kWh] based on the count value counted by the power measurement counter 7 and an instrument constant [pulse / kWh] preset for the inductive watt-hour meter.
[0022]
Also, the counting by the average power measurement counter 8 is performed as shown in FIG. 3C at every predetermined fixed time t shown in FIG. 3A, for example, every 30 [sec]. That is, the average power measurement counter 8 counts up the count value to 1, 2, 3,..., N−1, n each time the edge change of the electric pulse p is detected during the first fixed time t. I do. Then, every time the edge change of the electric pulse p is detected during the next fixed time t, the count value is counted up to 1, 2, 3,..., K-1, k. Thereafter, the edge change of the number of electric pulses p input within that time is counted at regular time intervals t in the same manner.
[0023]
The CPU 4 calculates the number of power amount pulses from the count value of the average power measurement counter 8 at each of the timings t1, t2,. Store it in memory separately from the number. Then, the obtained power amount pulse number P [pulses], measurement time (constant time) t [h], and instrument constant α [pulse / kWh] within the measurement time are calculated by the following arithmetic expressions (1) to (4). To calculate the short-time average power K [kW] of the circuit to be measured. The arithmetic expression (1) is used when the power distribution system of the circuit under measurement is a single-phase two-wire system, the arithmetic expression (2) is a single-phase three-wire system, the arithmetic expression (3) is a three-phase three-wire system, and an arithmetic expression (4) is used in the case of a three-phase four-wire system.
[0024]
K = P / (t × α) (1)
K = P / (2 × t × α) (2)
K = P / {(3) ^1/2 × t × α} (3)
K = P / (3 × t × α) (4)
[0025]
The integrated power consumption W and the short-time average power K thus calculated are displayed on the liquid crystal display 9. In addition, communication is performed with an external device via the communication function I / F circuit 10 as necessary, and the external device confirms the communication.
[0026]
According to the induction-type watt-hour meter according to the present embodiment, the conventional induction-type watt-hour meter is provided with the average power measurement counter 8, and is used in the circuit to be measured by counting the electric pulses p at regular time intervals t. The short-time average power K can be obtained. Therefore, the short-time average power K of the circuit under measurement is measured by the inductive watt-hour meter alone. For this reason, it is not necessary to install a dedicated average power measuring device as in the related art, and the short-time average power can be measured at a low cost. In addition, if a dedicated average power meter is not required, there is no need for a space to install it, and the installed equipment can be compactly installed on the wall of the customer's house with the watt-hour meter alone, without damaging the appearance of the house. .
[0027]
When the circuit to be measured has multiple phases, the rotation of the rotor 1 is electromagnetically induced by the magnetic flux generated by combining the current coils of each phase and the magnetic flux generated by combining the voltage coils of each phase. . Therefore, in a power distribution system other than the single-phase two-wire system, only a power amount pulse obtained by combining a plurality of circuits can be obtained. However, if the configuration is such that the short-time average power K is calculated based on the count value of the average power measurement counter 8 according to the arithmetic expressions of the equations (1) to (4) as in the present embodiment described above, Although the average power cannot be measured, the short-time average power can be measured at a low cost as a guide.
[0028]
Further, in this embodiment, the short-time average power used by the circuit under measurement is averaged and used repeatedly at regular intervals, so that the short-time average power K of the circuit under measurement is grasped in real time at regular intervals. You. However, it is not always necessary to adopt a configuration in which the average power K is repeatedly calculated every predetermined time t as in the present configuration, and the short-time average power used by the circuit under measurement only during the predetermined time t is used. K may be calculated. In this case, the average power K of the circuit under test is not grasped in real time, but it is possible to grasp the average power K of the circuit under test over a certain period of time t.
[0029]
【The invention's effect】
As described above, according to the present invention, the number of pulses generated during a predetermined period of time is counted by the pulse counting unit, and based on this count value, the average power calculating unit receives the pulse during the predetermined period of time. The short-time average power used by the measurement circuit is calculated. Therefore, the short-time average power of the circuit to be measured is measured by the inductive watt-hour meter alone. For this reason, it is not necessary to install a dedicated average power measuring instrument, and it is possible to measure the average power in a short time at a low cost.In addition, a space for installing the dedicated average power measuring instrument is not required, and the aesthetic appearance of the customer house can be improved. There is no loss.
[0030]
Further, if the short-time average power used in the circuit under test is averaged and used repeatedly at regular time intervals, the short-time average power of the circuit under test can be grasped in real time at regular time intervals. In addition, if the average power calculation means is configured to calculate the short-time average power by a predetermined calculation formula, accurate average power measurement cannot be performed, but the average power measurement as a guide can be performed at a low cost.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing a configuration of a hybrid inductive watt-hour meter according to an embodiment of the present invention.
FIG. 2 is a timing chart illustrating a counting mechanism in an average power measurement counter and a power amount measurement counter.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotor 2 ... Signal disk 2a ... Wing part 2b of signal disk 2 ... Notch 3 of signal disk 2 ... Optical coupling element 4 ... CPU
5 power supply circuit 6 pulse I / F circuit 7 power amount measurement counter 8 average power measurement counter 9 liquid crystal display 10 communication function I / F circuit 11 power failure detection circuit 12 nonvolatile memory 13 protection circuit

Claims (3)

According to the power consumption of the circuit to be measured distributed by the multi-phase power distribution method, the magnetic flux generated by combining the current coils of each phase and the magnetic flux generated by combining the voltage coils between each phase are electromagnetically induced to rotate. A rotor, pulse generating means for generating a predetermined number of electric pulses per unit power consumption according to the rotation of the rotor, and integrating the number of pulses generated by the pulse generating means to integrate the circuit to be measured. In an induction-type watt-hour meter comprising: a power-amount measuring unit for calculating the power amount,
A pulse counting unit for counting the number of pulses generated by the pulse generating unit during a predetermined period of time; and the circuit to be measured during the predetermined period of time based on the number of pulses counted by the pulse counting unit. And an average power calculating means for calculating a short-time average power used by averaging the power in a built-in power meter. The pulse counting means counts the number of pulses generated by the pulse generating means at every fixed time, and the average power calculating means averages a short time average power used by the circuit to be measured every fixed time. The inductive watt-hour meter with average power measurement function according to claim 1, wherein The average power calculating means distributes the number of pulses counted by the pulse counting means to the predetermined number of pulses generated per unit power consumption by the pulse generating means, the predetermined time, and the circuit to be measured. The average power measuring function according to claim 1 or 2, wherein the short-time average power used in the circuit under measurement is calculated by dividing by a product of a coefficient corresponding to a phase of a power distribution method. Inductive watt-hour meter.

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