JPH078778U - Digital energy meter - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a digital type electric energy meter that outputs integrated value data according to the amount of electric power used. [Structure] An electric power of the line 1 is measured and integrated through an instrument transformer 2a, 2b and a current transformer 3a, 3b connected to the line 1, and an integrated value is stored as an absolute value of the electric energy. The digital power meter 4 determines the multiplication factor when outputting the absolute value of the power amount to the monitor control device 5 connected by the optical fiber cable 6 or the like. Digital type electricity meter 4
The effective digit range of the absolute value of the electric energy is specified by this determined multiplying factor, and the multiplying factor is output together with the numerical value of the effective digit range.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is used in a power amount monitoring system that collects and monitors the power amount of multiple lines in the center, measures the line power, and accumulates the absolute value of the power amount in the central monitoring control device. To the improvement of the digital type electric energy meter that outputs to the.

[0002]

[Prior art]

 The electric energy monitoring system has a method of transmitting the measured electric energy to the host as an absolute value (numerical value). In such a system, multiple digital energy meters are used to measure the power of each line through the instrument transformer and current transformer connected to multiple lines, and the total power is calculated by integrating the power. The absolute value of this electric energy is output at fixed time intervals or when there is a request from the monitoring control device. The monitoring and control device monitors the electric energy by capturing the absolute value of the electric energy output by the multiple digital electric energy meters in this way and processing it collectively.

[0003]

[Problems to be solved by the device]

 However, a digital watt-hour meter used in a general watt-hour monitoring system converts, for example, a 5-digit numerical value into 3-byte data and outputs it as the absolute value of the wattage of the power measurement target line. In addition, a general digital type watt hour meter displays the absolute value of the watt hour in five digits on the main body with an LED or the like, and outputs this displayed value to the monitoring control device as the absolute value of the watt hour.

Therefore, in a power amount monitoring system in which the digital power meter outputs the absolute value of the power amount to the monitoring control device at regular time intervals, the amount of change in the absolute value of the power amount at constant time intervals is extremely large. If it is very small, the error that occurs when the monitoring and control device calculates the actual amount of power used (the amount of change in the absolute value of the amount of power) becomes large, and there is the drawback that detailed power monitoring cannot be performed.

For example, in an electric energy monitoring system in which a digital electric energy meter outputs an absolute value of electric energy every hour, the absolute value of the electric energy accumulated at the previous output was 12345.6. To do. In this case, 12345 is displayed and 6 is not displayed on the digital type electric energy meter, and 12345 is transmitted to the monitoring controller as the absolute value of the electric energy. Then, when the absolute value of the electric energy stored in the digital electric energy meter at the time of this output is 12345.9, the data output to the monitoring and control device becomes 12345 also this time. Since the monitoring and control device takes in the output of the digital type electric energy meter and calculates the difference from the data transmitted last time as the electric power consumption for one hour, the electric power consumption during this period is judged to be 0.

Further, even if the absolute value of the electric energy integrated at this output is 12346.0, the digital energy meter outputs 12346 as the absolute value of the electric energy to the monitoring control device. The supervisory controller determines that the amount of electric power used for this one hour is 1, and the ratio of the error from the actual amount of electric power used, 0.4, increases.

As described above, when the change in the power consumption is very small, the error becomes large, and there is a drawback that the power amount cannot be monitored precisely.

An object of the present invention is to provide a digital type electric energy meter that outputs absolute value data of electric energy according to the amount of electric power used.

[0009]

[Means for Solving the Problems]

 The digital energy meter of the present invention measures the power of the line through an instrument transformer and a current transformer connected to the line and stores the integrated value as an absolute value of the power amount in n digits. Absolute value storage means, output data reading means for reading m consecutive digits (n> m) of the absolute value of the electric energy as output data, and a leading digit when the output data is read by the output data reading means. The output data read out by the output data reading means and the output means for outputting the output data read by the output data reading means together with the output data read by the output data reading means. And

Further, the multiplying factor determining unit is a unit that determines the multiplying factor based on a time when the output unit outputs the output data.

[0011]

[Action]

 In the digital energy meter of the present invention, the power of the line is measured through the voltage transformer and the current transformer connected to the line, and the integrated value is used as the absolute value of the power amount in n digits. Remember. The digital energy meter determines the multiplication factor when outputting the absolute value of the amount of electricity, and reads the m-digit data as output data with the digit position specified by this multiplication factor as the leading digit. The digital energy meter outputs the multiplication factor determined together with this output data.

With the above configuration, the digital power meter specifies the effective digit range of the absolute value of the power amount by determining the multiplication factor. For example, when the absolute value of the electric energy is 12345.6, 12345 is the output data when the determined multiplication factor is 1, and 23456 is the output data when the multiplication factor is 0.1. This makes it possible to perform fine power monitoring by making the lowest digit data valid data.

Further, the multiplication factor is determined based on the time for outputting the output data.

With such a configuration, the multiplying factor is determined to be 1 in a time zone such as daytime where the power consumption is large, and the multiplying factor is determined to be 0.1 in a time zone such as midnight when the power consumption is small. . As a result, it is possible to monitor the amount of electric power according to the amount of electric power used in each time period.

[0015]

【Example】

 FIG. 1 is a diagram showing a configuration of a power amount monitoring system. The electric energy monitoring system includes a transformer for transformers (PT) 2a, 2b and current transformers (CT) 3a, 3b connected to the line 1, and a transformer for transformers 2a, 2b and current transformers 3a, 3b. It is provided with a digital type electric energy meter 4 connected to the secondary side, and a supervisory control device 5 which takes in the output of the digital type electric energy meter 4 and monitors the electric energy. The digital power meter 4 and the monitor control device 5 are connected by an optical fiber cable 6.

FIG. 2 is a diagram showing a configuration of a digital type electric energy meter which is an embodiment of the present invention. The digital type electric energy meter 4 includes analog filters 11, 12, 13, 14 to which the outputs of the instrument transformers 2a, 2b and the current transformers 3a, 3b connected to the lines are input, and the analog filter 11 described above. Sample-hold circuits 15, 16, 17, and 18 for sampling and holding the outputs of ˜14 at a predetermined cycle, and the outputs of the sample-hold circuits 15 to 18 are taken and one of them is selected and output. A multiplexer 19, an A / D converter 20 that takes in the output of the multiplexer 19 and converts it into digital data, a ROM 21 in which an operation program and the like are written in advance, and a CPU 22 that executes the program written in the ROM 21. And a RAM 23 for temporarily storing data etc. generated during operation, and measurement of absolute value of electric power etc. An output unit 24 for outputting data, and a.

In the digital electric power meter 4 having the above-described configuration, the CPU 22 operates according to a program written in the ROM 21 in advance. The digital energy meter 4 takes in the outputs of the instrument transformers 2a and 2b and the current transformers 3a and 3b connected to the line 1 into the analog filters 11 to 14. The analog filters 11 to 14 remove unnecessary frequency band components in advance in order to prevent the influence of aliasing noise generated by digital signal processing. The outputs of the analog filters 11 to 14 are taken into the sample and hold circuits 15 to 18 and inputted to the multiplexer 19.

The multiplexer 19 selects the outputs of the sample hold circuits 15 to 18 and inputs them to the A / D converter 20. The A / D converter 20 converts the input signal into digital data and outputs it. The CPU 22 calculates the instantaneous power based on the output of the A / D converter. The CPU 22 integrates the calculated instantaneous electric power with the absolute value of the electric energy stored in the RAM 23. The digital energy meter 4 repeats the above operation to update the absolute value of the energy.

For example, in an electric energy monitoring system that outputs the absolute value of the electric energy accumulated every hour, the digital electric energy meter 4 outputs the absolute value of the electric energy to the monitoring control device 5 at the time. Then, the absolute value of the electric energy stored in the RAM 23 is read out. In addition, the digital watt hour meter 4 determines 1 as a multiplication factor when the power consumption is high during the day, and 0.1 when the power consumption is low at midnight. It is set in advance.

The CPU 22 reads the current time from a clock circuit (not shown) and determines the multiplication factor. For example, assume that the absolute value of the electric power amount stored in the RAM 23 of the digital electric power meter 4 is 12345.6. At this time, if the selected multiplication factor is 1, as shown in FIG. 3, the digital type electric energy meter 4 outputs 12345 and the multiplication factor 1. On the other hand, when the selected multiplying factor is 0.1, the digital type electric energy meter 4 outputs 23456 and the multiplying factor of 0.1 with the thousandth digit as the leading digit. At this time, the decimal point is not output. That is, when 0.1 is selected as the multiplication factor, 1 which is the maximum digit of the absolute value of the electric energy is not transmitted to the monitoring control device 5, but 6 which is the minimum digit is transmitted. However, when monitoring the amount of electricity, there is no problem because the absolute value of the amount of electricity is not important and the amount of change per hour is important.

The monitoring control device that has received the absolute value of the electric energy and the multiplication factor from the digital type electric energy meter calculates the absolute value of the electric energy by multiplying the absolute value of the electric energy and the multiplication factor. That is, if 12345 is transmitted as the absolute value of the power amount, the absolute value of the power amount is 12345 if the multiplication factor is 1, and if the multiplication factor is 0.1, the absolute value of the power amount is absolute. The value is determined to be 1234.5.

That is, by changing the multiplying factor in accordance with the amount of electric power used during the day, midnight, etc., it is possible to finely monitor the central electric power.

In the embodiment of the present invention, the absolute value of the electric energy of the digital type electric energy meter is set in the daytime or the midnight time zone, but this is not a limiting element of the present invention. For example, the multiplying factor may be determined by the maximum digit in which the absolute value of the output electric energy changes with respect to the absolute value of the electric energy output last time. For example, the multiplier may be set to 0.1 when the maximum digit in which the numerical value has changed is 10 or less, and the multiplier may be set to 1 when the numerical value in the digit of 100 or more is changed.

Further, the multiplying factor may be determined by an instruction from the monitoring control device.

Furthermore, in the embodiment of the present invention, there are two kinds of multiplication factors, 1 and 0.1. This is also the absolute value of the electric energy stored in the RAM by the digital energy meter in the embodiment of the present invention. This is because the number of effective digits is set to 6 and, for example, when the number of effective digits is 7, it is possible to monitor the amount of electric power with three multiplication factors.

[0026]

[Effect of device]

 As described above, according to the present invention, the absolute value of the electric energy is processed and output by processing the absolute value of the electric energy according to the multiplication factor determined according to the time of day when the electric power consumption is low such as midnight. Power consumption can be monitored in detail.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a power amount monitoring system.

FIG. 2 is a diagram showing a configuration of a digital type electric energy meter which is an embodiment of the present invention.

FIG. 3 is a diagram showing a structure of absolute value data of the digital type electric energy meter according to the embodiment.

[Explanation of symbols]

 1-Line 4-Digital Energy Meter 21-ROM 22-CPU 23-RAM 24-Output Unit

Claims (2)

[Scope of utility model registration request] 1. A value obtained by measuring and integrating electric power of the line through an instrument transformer and a current transformer connected to the line is n.
Absolute value storage means for storing as an absolute value of electric energy in digits,
Output data reading means for reading out consecutive m digits (n> m) of the absolute value of the electric energy as output data, and a multiplication factor for designating the position of the leading digit when the output data is read by the output data reading means. Multiplying factor determining means for determining, and output means for outputting the multiplying factor determined by the multiplying factor determining means together with the output data read by the output data reading means,
A digital type electric energy meter characterized by being equipped with. 2. The digital power meter according to claim 1, wherein the multiplying factor determining unit is a unit for determining the multiplying factor based on a time when the output data is output by the output unit.