JP2002098722A - Commercial frequency discrimination method and operation processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a commercial frequency discrimination method and an operation processing device capable of discriminating the frequency of a commercial power source without installing separately a mechanism or a circuit for discriminating the frequency of a commercial alternating voltage or a commercial alternating current in the commercial power source. SOLUTION: In this method for discrimination the frequency of the commercial power source by using data acquired by a sampling mechanism provided in this operation processing device 1, first of all, the inputted commercial power source frequency is assumed as 50 Hz, and a sampling control signal having a sampling period of 1/50 n second is given to a control terminal of a sample hold circuit 2 and sampling is executed. Sampling data are converted by an A/D converter 3, and voltage values or current values in sampling data selected optionally and in sampling data after 1/50 second, namely, after phase shift of 360 deg. from the data are confirmed by an operation processor 4, and the frequency of the commercial power source is discriminated by whether both values roughly agree with each other or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for identifying the frequency of a commercial AC voltage or a commercial AC current applied to an arithmetic processing unit such as a protective relay having a digital filter.

[0002]

2. Description of the Related Art Conventionally, protective relays have been used to protect various devices connected to distribution lines. As shown in FIG. 5, a protection relay 1 having a digital filter
01, the input voltage or current is sampled by the sample and hold circuit 102, and this data is A / D
A / D conversion is performed by the converter 103, and a predetermined calculation process is performed by the calculation processing circuit 104. Since the protective relay 101 is connected to the distribution line to which the commercial power is connected, it is necessary to use the protection relay 101 by switching to the frequency of the commercial power at the place where it is connected.

That is, as is well known, since the commercial power frequency is different between eastern Japan and western Japan, in order to be able to use the same protective relay throughout Japan, conventionally, the frequency is changed according to the input commercial power frequency. Is provided, and the mechanism is artificially switched to identify the input frequency to the protection relay. In some cases, a dedicated circuit is provided for identifying the input frequency.

[0004] In addition to the above protective relay, there are a plurality of appliances using a commercial power supply, such as home electric appliances, that need to switch the commercial power supply frequency.

In the case of the protection relay 101, as shown in FIG. 5, a dedicated circuit is provided for identifying an input frequency, and the dedicated circuit is used for comparing an AC input waveform to form a rectangular wave. It comprises a comparator 105, an oscillator 106 for forming a pulse wave, and an AND circuit 107 for calculating a rectangular wave and a pulse wave.

When the input frequency is identified by using a circuit as shown in FIG. 5, the following method is performed. That is, as shown in FIG.
A pulse is generated from 6. Then, the counting circuit 108 counts the number of pulses from the point of crossing the zero point to the next point of zero crossing in the input commercial power supply. Since the number of pulses from the oscillator 106 in one cycle of the commercial power supply frequency differs between the case of 50 Hz and the case of 60 Hz, the commercial power supply frequency is identified based on the counted number of pulses. In FIG. 6, 5
The number of pulses at 0 Hz is B, and the number of pulses at 60 Hz is A.

[0007]

However, in the protection relay having such a configuration, when the mechanism for setting the frequency is artificially switched, there is a possibility that the setting of the input mechanism may be erroneously performed at the time of installation. In addition, when the input frequency is identified using the circuit shown in FIG. 5, there is a problem that the circuit becomes completely unnecessary after the frequency identification is completed.

Accordingly, the present invention has been made to solve the above-mentioned problem, and an object of the present invention is to separately provide a mechanism and a circuit for identifying the frequency of a commercial AC voltage or a commercial AC current in a commercial power supply. An object of the present invention is to provide a commercial frequency identification method and an arithmetic processing device capable of identifying the frequency of a commercial power supply without providing the same.

[0009]

According to the present invention, a commercial AC voltage or a commercial AC current is sampled in at least one of a sampling period of 1/50 ns and 1/60 ns,
Sampling cycle 1 for commercial AC voltage or commercial AC current
In the case of sampling at / 50 nsec, the voltage value or the current value is compared between the first data arbitrarily sampled and the second data 1/50 sec after the first data. When the commercial AC voltage or the commercial AC current is sampled at a sampling cycle of 1/60 nsec, third data arbitrarily sampled,
A voltage value or a current value is compared with the fourth data 1/60 second after the third data.
Is characterized.

In this configuration, as a commercial frequency identification method, a commercial AC voltage or a commercial AC current is sampled in at least one of a sampling period of 1/50 ns and 1/60 ns, and is sampled at a sampling period of 1/50 ns. Compares the voltage value or the current value of the arbitrarily sampled first data with the second data 1/50 second after the first data and finds that 50H
z. In addition, when sampling is performed at a sampling period of 1/60 nsec, the arbitrarily sampled third
Data, fourth data 1/60 second after the third data,
Comparing the voltage value or the current value of
Hz. This makes it possible to easily identify the commercial frequency at any point, and it is not necessary to always use the same point as in the conventional pulse counting using a zero-cross point.

Further, according to the present invention, a commercial AC voltage or a commercial AC current is supplied at a sampling period of 1/50 ns and 1/6 ns.
0 n seconds, and when the commercial AC voltage or the commercial AC current is sampled at a sampling period of 1/50 n seconds, the first data
The ratio of the rate of change of the voltage or current from the fifth data to the fifth data after one sampling cycle of data and the rate of change of the voltage or current from the fifth data to the sixth data after one sampling cycle of the fifth data. And the second data from the second data
The ratio of the rate of change of the voltage or current from the seventh data to the seventh data after one sampling cycle of the data or from the seventh data to the eighth data after one sampling cycle of the seventh data. Are compared with each other.
0 Hz, and when the commercial AC voltage or commercial AC current is sampled at a sampling cycle of 1/60 nsec,
The rate of change of the voltage or current from the third data to the ninth data after one sampling cycle of the third data, and the voltage or current from the ninth data to the tenth data after one sampling cycle of the ninth data. A ratio of a current variation rate, a voltage or current variation rate from the fourth data to the eleventh data after one sampling cycle of the fourth data, and one sampling of the eleventh data from the eleventh data. The ratio of the fluctuation rate of the voltage or current up to the twelfth data after the cycle is compared with the ratio, and if they substantially match, the frequency is identified as 60 Hz.

In this configuration, as a commercial frequency identification method, a commercial AC voltage or a commercial AC current is sampled in at least one of a sampling period of 1/50 ns and 1/60 ns, and is sampled at a sampling period of 1/50 ns. And the rate of change of the voltage or current from the arbitrarily sampled first data to the fifth data after one sampling cycle of the first data, and from the fifth data to the fifth
The ratio between the voltage or current fluctuation rate up to the sixth data after one data sampling period, and 1/50 of the first data
The rate of change of the voltage or current from the second data after second to the seventh data after one sampling cycle of the second data;
The ratio of the fluctuation rate of the voltage or current from the data to the eighth data after one sampling cycle of the seventh data is compared, and if they are almost equal, 50 Hz is identified. When the sampling is performed at a sampling period of 1/60 nsec, the voltage or current fluctuation rate from the arbitrarily sampled third data to the ninth data after one sampling period of the third data, and the ninth data to the ninth data The rate of change of the voltage or current up to the tenth data after one sampling cycle of
, The rate of change in voltage or current from the fourth data 1/60 seconds after the third data to the eleventh data after one sampling cycle of the fourth data, and one sampling of the eleventh data from the eleventh data The rate of change of the voltage or current up to the twelfth data after the cycle is compared with the ratio, and if they substantially match, the frequency is identified as 60 Hz. As a result, even when the commercial power frequency to be identified fluctuates due to the influence of noise or the like, the commercial frequency can be reliably identified.

Further, the present invention provides a sampling and holding means for sampling an input voltage or current at a predetermined cycle, an A / D conversion means for converting analog data output by the sampling and holding means into digital data, An arithmetic processing unit for performing an arithmetic processing based on the digital data output from the A / D conversion means, wherein the arithmetic processing means has a sampling period of 1/50 nsec and 1/50 60n
Second sampling control signal, and the sample-and-hold means controls the sampling period 1
When sampling is performed every / 50n seconds, the voltage value or the current value of the arbitrarily sampled first data and the second data 1/50 second after the first data are compared, and if they substantially match, the frequency is set to 50 Hz. When the sample-and-hold means performs sampling at a sampling period of 1/60 nsec, the voltage value or the current value of the arbitrarily sampled third data and the fourth data 1/60 sec after the third data are compared. When the frequency is almost the same, the frequency of the commercial AC voltage or the commercial AC current is identified as 60 Hz.

In this configuration, the arithmetic processing unit includes a sample-and-hold means for sampling the input voltage or current at a predetermined cycle, and an analog-to-digital converter for converting analog data output from the sample-and-hold means into digital data.
/ D conversion means, and arithmetic processing means for performing arithmetic processing based on the digital data output from the A / D conversion means. Providing at least one sampling control signal of 1/60 ns;
When the sample-and-hold means performs sampling at a sampling period of 1/50 n seconds, the voltage value or the current value of the arbitrarily sampled first data and the second data 1/50 second after the first data are compared. 50 when almost matched
Hz. Also, when the sample and hold means samples at a sampling period of 1/60 nsec,
Arbitrarily sampled third data and third data 1
The voltage value or the current value of the fourth data after / 60 seconds is compared, and if they substantially match, it is identified as 60 Hz. This allows
The commercial frequency can be identified using the means included in the arithmetic processing device, and it is not necessary to separately provide a frequency identification circuit or mechanism.

In addition, in the present invention, when the sample-and-hold means performs sampling at a sampling period of 1/50 nsec, the arithmetic processing means may execute the first data after one sampling cycle of the first data from the first data. The ratio of the rate of change of the voltage or current up to 5 data, the rate of change of the voltage or current from the fifth data to the sixth data after one sampling cycle of the fifth data, and A rate of change of voltage or current from the seventh data to seventh data after one sampling cycle of the second data, a rate of change of voltage or current from the seventh data to eighth data after one sampling cycle of the seventh data, When the value obtained by comparing the ratios of the two is almost the same, the frequency is set to 50 Hz. When the sample-and-hold means performs sampling at a sampling period of 1/60 nsec, The rate of change of the voltage or current from the third data to the ninth data after one sampling cycle of the third data, and the voltage or current from the ninth data to the tenth data after one sampling cycle of the ninth data. The ratio of the variation rate, and the ratio of the fourth data to 1 of the fourth data
The rate of change of the voltage or current up to the eleventh data after the sampling period, and 1 of the eleventh data from the eleventh data
The frequency of the commercial AC voltage or the commercial AC current is identified as 60 Hz when the value obtained by comparing the ratio of the voltage or current fluctuation rate up to the twelfth data after the sampling period substantially coincides with each other.

In this configuration, the arithmetic processing unit includes a sample-and-hold means for sampling the input voltage or current at a predetermined cycle, and an analog-to-digital converter for converting the analog data output from the sample-and-hold means into digital data.
/ D conversion means, and arithmetic processing means for performing arithmetic processing based on the digital data output from the A / D conversion means, wherein the arithmetic processing means comprises a sampling and holding means in which a sampling period is 1/50 nsec. And the rate of change of the voltage or current from the arbitrarily sampled first data to the fifth data after one sampling period of the first data, and the variation rate of the voltage or current after one sampling period of the fifth data to the fifth data. The ratio of the voltage or current fluctuation rate up to 6 data, and the voltage or current fluctuation rate from the second data 1/50 second after the first data to the seventh data after one sampling cycle of the second data. When the value obtained by comparing the ratio of the voltage and the rate of change of the voltage or current from the seventh data to the eighth data after one sampling cycle of the seventh data substantially coincides with each other, the frequency becomes 50 Hz. Identifying Te. Further, when the sample-and-hold means performs sampling at a sampling period of 1/60 n seconds, a voltage or current fluctuation rate from arbitrarily sampled third data to ninth data after one sampling period of the third data, The ratio of the voltage or current fluctuation rate from the ninth data to the tenth data after one sampling cycle of the ninth data, and one sampling of the fourth data from 1/60 second after the third data The rate of change of the voltage or current up to the eleventh data after the cycle,
The first data after one sampling period of the eleventh data from the data
If the values obtained by comparing the ratio of the fluctuation rate of the voltage or current up to the two data and the ratio almost match, the frequency is identified as 60 Hz. As a result, the commercial frequency can be identified using the means provided in the arithmetic processing device, and even if the voltage or current of the commercial power supply fluctuates due to noise or the like, the commercial frequency can be identified reliably. It becomes possible.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of an arithmetic processing unit according to an embodiment of the present invention will be described. FIG. 1 is a block diagram showing a schematic configuration of an arithmetic processing device according to an embodiment of the present invention. The present invention identifies the frequency of a commercial power supply using data obtained by a sampling mechanism provided in the arithmetic processing device 1.

The arithmetic processing device 1 includes a sample hold circuit 2, an A / D converter 3, an arithmetic processor 4, a sampling cycle control circuit 5, and an inverter 6. The input terminal of the sample hold circuit 2 is the input terminal 7 of the arithmetic processing unit 1.
And the output terminal of the sample hold circuit 2 is A /
Connected to the input terminal of D converter 3. An output terminal of the A / D converter 3 is connected to an input terminal of the arithmetic processing unit 4, and an output terminal of the arithmetic processing unit 4 is connected to an input terminal of the sampling cycle control circuit 5. An output terminal of the sampling cycle control circuit 5 is connected to an input terminal of the inverter 6, and an output terminal of the inverter 6 is connected to a control terminal of the sample and hold circuit 2. The arithmetic processing unit 4 includes a frequency identification arithmetic unit 11
For identifying the input frequency.

In the present invention, when the commercial power frequency is 50
It is assumed that the input commercial power frequency is either 50 Hz or 60 Hz regardless of Hz or 60 Hz. Then, based on this assumption, the arithmetic processing unit 4 generates an AC frequency of n times the commercial frequency, that is, 50 nHz or 60 nHz, and outputs a sampling control signal having a sampling period of 1/50 nsec or 1/60 nsec to the sample hold circuit 2. Sampling and holding circuit 2
Perform sampling with. Then, the sampled data is converted into digital data by the A / D converter 3, and the arithmetic processing unit 4 checks the commercial AC voltage value or the commercial AC current value in the arbitrarily selected sampling data. Next, 1/5 from the arbitrarily selected sampling data
After 0 seconds or 1/60 seconds, that is, after the 360 ° phase shift, the sampling data commercial AC voltage value or commercial AC current value is confirmed. Then, by comparing the two, the frequency of the commercial power supply is identified based on whether the voltage value or the current value substantially matches.

As described above, by assuming the frequency of the commercial power supply, and comparing the AC voltage or the AC current of the commercial power supply at an arbitrary point and a point after a phase shift of 360 °, the assumed commercial power If the power supply frequencies are correct and do not match, it can be easily determined that the assumed commercial power supply frequency was incorrect. If the assumption is wrong, it is assumed that the frequency is the other frequency, and the determination is performed again, so that it is possible to determine whether the other frequency or a frequency different from the frequency of the commercial power supply is input.

FIG. 2 is a commercial power supply frequency waveform diagram when sampling is performed at a sampling period of 1/600 second. FIG. 2A shows that the supplied commercial power frequency is 50H.
z, and the sampling is performed at a sampling period of 1/600 second as an example of a sampling period of 1/50 n second. Therefore, after arbitrary sampling data (first data) and 360 ° phase displacement of the first data (1/50
The voltage value or current value of the second data after (seconds) substantially matches. Therefore, A = A ′, B = B ′, C =
C '. . . Holds, and the commercial power supply frequency can be identified using arbitrary sampling data.

On the other hand, FIG. 2B shows a case where the frequency of the supplied commercial power supply is 60 Hz, and the sampling period 1 /
Since the sampling is performed in 600 seconds, the voltage value or the current value of the arbitrary sampled data does not match the data 1/50 second after the data. Therefore, in this case, for example, sampling is performed at a sampling period of 1/720 second, and the frequency is identified again in the same manner as described above, whereby the commercial power supply frequency can be identified as 60 Hz.

FIG. 3 is a commercial power supply frequency waveform diagram when sampling is performed at a sampling period of 1/720 second. FIG. 3A shows that the supplied commercial power frequency is 60H.
In the case of z, sampling is performed at a sampling period of 1/720 second as an example of a sampling period of 1/60 n second. Therefore, after arbitrary sampling data (third data) and 360 ° phase shift of the third data. (1/60
The voltage value or the current value of the fourth data (after the second) substantially matches. Therefore, a = a ', b = b', c = c '. . .
Holds, and the commercial power supply frequency can be identified using arbitrary sampling data.

On the other hand, FIG. 3B shows a case where the frequency of the supplied commercial power supply is 50 Hz, and the sampling period 1 /
Since sampling is performed at 720 seconds, the voltage value or the current value of the arbitrary sampled data does not match the data 1/60 seconds after the data. Therefore, in this case, for example, sampling is performed at a sampling period of 1/600 second, and the frequency is identified again in the same manner as described above, whereby the commercial power supply frequency can be identified as 50 Hz.

The method of identifying the frequency is not limited to the case where the AC voltage or the AC current of the commercial power supply fluctuates in a fixed cycle, and the case where the AC voltage or the AC current periodically increases due to the influence of noise or the like. Identify the frequency of the commercial power supply. That is, the frequency of the commercial power supply is identified based on whether or not the ratio of the fluctuation rate of the AC voltage or the AC current at the selected point and the adjacent point is the same.

Specifically, the frequency of the commercial power supply is set to, for example, 5
Assuming 0 Hz, the sampling period is determined based on this assumption, and sampling is performed. At this time, FIG.
As shown in the figure, the rate of change of the voltage or current from the point A which is the first data to the point B which is the fifth data, and the voltage or the current from the point B which is the fifth data to the point C which is the sixth data, The ratio between the rate of change of the current and the current is determined (BC / AB).

The rate of change of the voltage or current from the point A 'which is the second data to the point B' which is the seventh data, and the rate of change of the voltage or current from the point B 'which is the seventh data to the point C' which is the eighth data Of the voltage or current fluctuation rate (B′C ′)
/ A'B ').

Then, the ratio of both (BC / AB and B'C ')
/ A'B '), and if they substantially match, the assumed frequency is correct, and if they do not match, it is assumed that the assumed frequency is wrong and the other frequency is assumed, and identification is performed again.

Similarly, the frequency of the commercial power supply is set to, for example, 60H
Sampling may be performed by assuming z and determining the sampling period based on this assumption. At this time, FIG.
As shown in (A), from the point a, which is the third data, to the ninth data
The ratio between the rate of change of the voltage or current up to point b, which is the data, and the rate of change of voltage or current from point b, which is the ninth data, to point c, which is the tenth data, is obtained (bc / a
b).

Further, from the point a ', which is the fourth data, to the eleventh
The rate of change of the voltage or current up to point b ', which is the data,
From point b 'which is eleventh data to c' which is twelfth data
The ratio between the voltage or current fluctuation rate up to the point is determined (b'c '/ a'b').

Then, the ratio of both (bc / ab and b'c ')
/ A'b ') are compared, and if they substantially match, the assumed frequency is correct, and if they do not match, the assumed frequency is wrong, and the identification is performed again assuming that the other frequency is used.

Next, a method of identifying 50 Hz / 60 Hz in the case of 30 ° fixed sampling will be described with reference to FIG.
This will be described with reference to FIG. FIG. 4 is a flowchart for explaining a method of identifying a commercial power supply frequency.

First, the arithmetic processing unit 4 assumes that the input is 60 Hz, and performs a 30 ° fixed sampling. Based on this assumption, the arithmetic processing unit 4 calculates a sampling frequency of 12 times the commercial frequency of 60 Hz, that is, 720 Hz. (Step 51), and the sampling period is 1/720
A second sampling control signal is supplied to the control terminal of the sample and hold circuit 2, and sampling is performed by the sample and hold circuit 2 (step 52). The arithmetic processing unit 4 compares the voltage value or the current value between the arbitrary data in the collected sampling data and the data after 1/60 second which is the data after 360 ° phase shift from the data (step 53). ). If the comparison results are substantially the same, the arithmetic processing unit 4 determines that the input frequency is 60 Hz, and sets the sampling period to 1/720 second thereafter (step 54). Then, the process ends.

On the other hand, if the comparison results do not match, then the input frequency is assumed to be 50 Hz and the commercial frequency 50 Hz
The sampling frequency of 600 Hz is generated by the arithmetic processing unit 4 (step 61), and a sampling control signal having a sampling period of 1/600 second is supplied to the control terminal of the sample and hold circuit 2 so that the sample and hold circuit 2
Sampling is performed (step 62). Arithmetic processor 4
Compares the voltage value or the current value between the arbitrary data in the collected sampling data and the data after 1/50 second which is the data after the phase shift of 360 ° from the collected data (step 63). And the arithmetic processor 4
If the comparison result is almost the same, the input frequency is
It is identified as 50 Hz, and thereafter the sampling period is 1 /
It is set to 600 seconds (step 64). Then, the process ends.

If the data do not match in step 63, the frequency is 50 Hz, 60 H
If it is not z, an error message is notified by a not-shown notifying unit (step 65), and the process ends.

[0036]

According to the present invention, the following effects can be obtained.

As a commercial frequency identification method, a commercial AC voltage or a commercial AC current is sampled in at least one of a sampling period of 1/50 nsec and 1/60 nsec. The voltage value or the current value of the first data thus obtained and the second data 1/50 second after the first data are compared, and if they substantially match, 50 Hz is identified. When the sampling is performed at a sampling period of 1/60 nsec, the voltage value or the current value of the arbitrarily sampled third data and the fourth data 1/60 sec after the third data are compared, If they match, it is identified as 60 Hz.
Therefore, the commercial frequency can be easily identified at any point.

As a commercial frequency identification method, a commercial AC voltage or a commercial AC current is sampled at a sampling period of 1/50.
When sampling at least one of n seconds and 1/60 n seconds and sampling at a sampling period of 1/50 n seconds, a voltage or current from arbitrarily sampled first data to fifth data after one sampling period of the first data And the ratio of the fluctuation rate of the voltage or current from the fifth data to the sixth data after one sampling period of the fifth data, and the second data after 1/50 second of the first data. The rate of change of the voltage or current up to the seventh data after one sampling period of the two data, and the seventh data to the seventh data
The ratio between the rate of change of the voltage or current up to the eighth data after one data sampling period is compared with each other. Also, the sampling period 1 /
When the sampling is performed at 60 nsec, the voltage or current fluctuation rate from the arbitrarily sampled third data to the ninth data after one sampling cycle of the third data, and the variability of the voltage or current after one sampling cycle of the ninth data to the ninth data The ratio of the voltage or current fluctuation rate up to the tenth data, and the voltage or current fluctuation from the fourth data 1/60 seconds after the third data to the eleventh data after one sampling cycle of the fourth data The rate is compared with the rate of change of the voltage or current from the eleventh data to the twelfth data after one sampling cycle of the eleventh data. Therefore, even when the commercial power frequency to be identified fluctuates due to the influence of noise or the like, the commercial frequency can be reliably identified.

Further, the arithmetic processing unit comprises: a sample and hold means for sampling the input voltage or current at a predetermined cycle; an A / D conversion means for converting analog data output from the sample and hold means into digital data; Arithmetic processing means for performing arithmetic processing based on the digital data output from the A / D conversion means, wherein the arithmetic processing means has at least one of a sampling period of 1/50 nsec and 1/60 nsec When one of the sampling control signals is supplied, when the sample-and-hold means samples at a sampling period of 1/50 nsec, the voltage of the first data arbitrarily sampled and the voltage of the second data 1/50 sec after the first data The values or the current values are compared, and if they substantially match, it is identified as 50 Hz. When the sample-and-hold means samples at a sampling period of 1/60 nsec, the voltage value or the current value of the arbitrarily sampled third data and the fourth data 1/60 sec after the third data are compared. If they almost match, the frequency is identified as 60 Hz. Therefore, the commercial frequency can be identified using the means included in the arithmetic processing device.

In addition, the arithmetic processing unit includes a sample and hold means for sampling the input voltage or current at a predetermined cycle, and an A / D conversion means for converting analog data output from the sample and hold means into digital data. Arithmetic processing means for performing arithmetic processing based on the digital data output by the A / D conversion means, wherein the arithmetic processing means is configured to execute the processing when the sample-and-hold means performs sampling every 1/50 nsec. The voltage or current fluctuation rate from the arbitrarily sampled first data to the fifth data after one sampling cycle of the first data, and the voltage from the fifth data to the sixth data after one sampling cycle of the fifth data Or the ratio of the current fluctuation rate to the second data from the second data 1/50 second after the first data
The rate of change of the voltage or current up to the seventh data after one sampling cycle of the data, and 1 of the seventh data to the seventh data.
If the values obtained by comparing the ratio between the voltage or current fluctuation rate up to the eighth data after the sampling period and the ratio substantially match, 5
Identify as 0 Hz. Further, when the sample-and-hold means performs sampling at a sampling period of 1/60 n seconds, a voltage or current fluctuation rate from arbitrarily sampled third data to ninth data after one sampling period of the third data, The ratio of the voltage or current fluctuation rate from the ninth data to the tenth data after one sampling cycle of the ninth data, and one sampling of the fourth data from 1/60 second after the third data A value obtained by comparing the ratio of the voltage or current fluctuation rate up to the eleventh data after the cycle with the voltage or current fluctuation rate from the eleventh data to the twelfth data after one sampling cycle of the eleventh data. Are almost coincident with each other and are identified as 60 Hz. Therefore, the commercial frequency can be identified using the means included in the arithmetic processing device, and the commercial frequency can be reliably identified even if the voltage or current of the commercial power supply fluctuates due to the influence of noise or the like. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an arithmetic processing device according to an embodiment of the present invention.

FIG. 2 is a commercial power supply frequency waveform diagram when sampling is performed at a sampling period of 1/600 second.

FIG. 3 is a commercial power supply frequency waveform diagram when sampling is performed at a sampling period of 1/720 second.

FIG. 4 is a flowchart for explaining a method for identifying a commercial power supply frequency.

FIG. 5 is a block diagram showing a schematic configuration of a conventional protection relay (operation processing device).

FIG. 6 is a waveform chart for explaining a conventional method for identifying a commercial power supply frequency.

[Explanation of symbols]

 1-arithmetic processor 2,102-sample-hold circuit 3,103-A / D converter 4,104-arithmetic processor 5,109-sampling period control circuit 105-comparator 106-oscillator 108-counter circuit

Claims (4)

[Claims] 1. A commercial AC voltage or a commercial AC current is sampled in at least one of a sampling period of 1/50 nsec and 1/60 nsec.
In the case of sampling at / 50 nsec, the voltage value or the current value is compared between the first data arbitrarily sampled and the second data 1/50 sec after the first data. Sampling cycle of commercial AC voltage or commercial AC current 1
When sampling is performed at / 60 nsec, the voltage value or the current value is compared between the arbitrarily sampled third data and the fourth data 1/60 second after the third data, and if they substantially match, it is identified as 60 Hz. A commercial frequency identification method, comprising: 2. A commercial AC voltage or a commercial AC current is sampled in at least one of a sampling period of 1/50 nsec and 1/60 nsec.
/ 50 nsec, the rate of change in voltage or current from the first data to the fifth data after one sampling cycle of the first data, and the rate of change of the voltage or current after one sampling cycle of the fifth data from the fifth data A ratio of the voltage or current fluctuation rate up to the sixth data, a voltage or current fluctuation rate from the second data to the seventh data after one sampling cycle of the second data, and the seventh data From the voltage or current fluctuation rate to the eighth data after one sampling cycle of the seventh data, and
Are compared with each other, the frequency is determined to be 50 Hz, and the commercial AC voltage or the commercial AC current is sampled at a sampling period of 1 Hz.
/ 60 nsec, the rate of change of the voltage or current from the third data to the ninth data after one sampling cycle of the third data, and the rate of change of the voltage or current from the ninth data after one sampling cycle of the ninth data And the rate of change of the voltage or current up to the tenth data, and the rate of change of the voltage or current from the fourth data to the eleventh data after one sampling cycle of the fourth data,
The rate of change of voltage or current from the eleventh data to the twelfth data after one sampling cycle of the eleventh data,
The commercial frequency identification method according to claim 1, wherein the frequency is compared with the frequency of the frequency, and when they substantially match, the frequency is identified as 60 Hz. 3. A sample-and-hold means for sampling an input voltage or current at a predetermined cycle, A / D conversion means for converting analog data output by the sample-hold means into digital data, and A / D conversion. An arithmetic processing means for performing arithmetic processing based on the digital data output by the means. The arithmetic processing means, wherein the sample and hold means has a sampling period of at least 1/50 nsec and 1/60 nsec. When one of the sampling control signals is supplied, and the sample-and-hold means performs sampling at a sampling period of 1/50 nsec, the first data arbitrarily sampled and the second data 1/50 sec after the first data Compare the voltage value or the current value of each other, and when they almost match, 50 Hz
And the sample-and-hold means makes the sampling period 1 /
When sampling is performed every 60 nsec, the voltage value or the current value of the arbitrarily sampled third data and the fourth data 1/60 second after the third data are compared, and if they substantially match, the frequency is set to 60 Hz. An arithmetic processing device for identifying a frequency of an AC voltage or a commercial AC current. 4. The method according to claim 1, wherein the arithmetic processing unit is configured to execute the sampling of the first data from the first data when the sample and hold unit performs sampling at a sampling period of 1/50 nsec.
A ratio between a rate of change in voltage or current up to fifth data after the sampling cycle and a rate of change in voltage or current from sixth data to sixth data after one sampling cycle of the fifth data; The voltage or current fluctuation rate from the second data to the seventh data after one sampling cycle of the second data, and the voltage or current from the seventh data to the eighth data after one sampling cycle of the seventh data And the ratio of
Is substantially equal to 50 Hz, the sampling and holding means sets the sampling period to 1/60.
When sampling is performed every n seconds, the rate of change in voltage or current from the third data to the ninth data after one sampling cycle of the third data, and one sampling of the ninth data from the ninth data The ratio of the voltage or current fluctuation rate up to the tenth data after the cycle, and the voltage or current fluctuation rate from the fourth data to the eleventh data after one sampling cycle of the fourth data,
The rate of change of voltage or current from the eleventh data to the twelfth data after one sampling cycle of the eleventh data,
The arithmetic processing device according to claim 3, wherein the frequency of the commercial AC voltage or the commercial AC current is identified as 60 Hz when a value obtained by comparing the ratio of the commercial AC voltage and the commercial AC voltage substantially coincides with each other.