JP3053888B2 - Harmonic measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring harmonics, and more particularly to a method for sampling harmonics contained in an alternating current flowing through an electric wire.

[0002]

2. Description of the Related Art In recent years, the number of loads used by consumers that perform switching operations such as inverter circuits has been increasing rapidly. , The frequency at which harmonics are included is increased. Since these harmonics cause various adverse effects such as heat generation of a motor used by a customer, it has been conventionally practiced to measure the location and time of occurrence of the harmonics in order to ascertain the cause of the occurrence. Have been.

FIG. 12 shows an example of the above-mentioned observation apparatus. In this observation device, the sensors 1 are attached to the respective phases of the distribution line L, and the detection values of the respective sensors 1 are input to the CPU 6 via the amplification filter 2 and the A / D conversion circuit 3.
Are sequentially stored in the data memory 11. As a sampling method of the CPU 6 at this time, as shown in FIG. 13, a method of sampling data every predetermined time, for example, every 10 minutes, and inputting the data to the data memory 11 is widely used.

[0004]

However, when data sampling is performed discretely as described above, it is not known what harmonics are generated between samplings. However, there is a problem that measurement cannot be performed even if there is a period in which the harmonic content is large.

An object of the present invention is to provide a harmonic measuring method capable of always accurately measuring harmonics.

[0006]

According to a first aspect of the present invention, an AC voltage value or a current value flowing through an electric wire is continuously sampled, and a predetermined value is specified from among the sampled data.
Raw data when the content ratio of the harmonic of the predetermined order is the maximum, and based on the raw data at that time, the raw data of each order is selected.
The gist of the present invention is a harmonic measurement method for calculating the harmonic content . According to a second aspect of the present invention, a voltage value or a current value of a three-phase alternating current flowing through an electric wire is continuously sampled for each phase , and harmonics of a predetermined order designated in advance for a predetermined phase from the sampled data. with wave content is to elect a raw data when the maximum, the predetermined order harmonic content of the 1-phase elect other two phases of raw data when the maximum value, when the Raw of each phase of
Calculate harmonic content of each order based on data
The gist of the method is a harmonic measurement method.

According to a third aspect of the present invention, a voltage value or a current value of a three-phase alternating current flowing through an electric wire is continuously sampled for each phase, and a preliminary value is obtained for each phase from the sampled data.
If because the specified predetermined order harmonic content of is the maximum
Kinosei data while selecting each phase of the
The raw data of the other two phases when the harmonic content of the predetermined order shows the maximum value is selected, and the harmonic data of the maximum value of each phase is compared, and the raw data of the largest content and the raw data at that time are compared. The raw data of the other two phases are selected, and the raw data of each phase at that time is selected.
The gist is a harmonic measurement method for calculating the harmonic content of each order based on the harmonic content .

[0008]

[Action] The AC voltage and current values flowing through the electric wire are continuously sampled, and the sampling is performed during sampling.
The height of the specified degree specified in advance from the ring data
The raw data with the highest harmonic content is selected,
The raw data at that time shows the harmonic content of each order.
It is used for calculation . Since the sampling is performed continuously in this manner, even if a state where the harmonic content is large occurs for a very short time, it is always detected.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the first invention will be described below with reference to FIGS. First, an observation device for implementing the harmonic measurement method of the present embodiment will be described. As shown in FIG. 2, three sensors 1 of the harmonic observation device are U, V, W of a distribution line L as an electric wire. Each sensor 1 is connected to a digital signal processing circuit 4 via an amplification filter 2 and an A / D conversion circuit 3. A data memory 5 is connected to each digital signal processing circuit 4, and each digital signal processing circuit 4 is connected to a common CPU 6. Further, a data analysis display unit 7 is connected to the CPU 6.

Next, a description will be given, with reference to the flow chart of FIG. 1, of a measurement state of harmonics by the harmonic observation apparatus thus configured. In this flowchart, steps 1 to 7 (S1 to S7) are processing performed by the U-phase digital signal processing circuit 4, step 8 (S8) is processing performed by the V-phase digital signal processing circuit 4, and step 9 ( S9) is a process performed by the W-phase digital signal processing circuit 4, step 1
Steps 0 and 11 (S10 and S11) are performed by the CPU 6.

First, the processing of the U-phase digital signal processing circuit 4 will be described. The voltage value of the U-phase distribution line L is detected by the sensor 1 and is amplified by the amplification filter 2 from the first to the 49th order (from the fundamental wave to the 49th order). Only frequency components up to 49 times the fundamental wave) are extracted, A / D converted by the A / D conversion circuit 3, and then input to the digital signal processing circuit 4. Digital signal processing circuit 4 is continuously samples the input through the amplification filter 2 data at a period of 49.152KH _Z by the A / D conversion circuit 3 in step 1, the data memory and the sampling data at Step 2 5 (hereinafter, this data is referred to as raw data).

The data sampled as described above is sequentially written into the data memory 5, and if it is determined in step 3 that data for 10 cycles has been written (the time s corresponds to 10 cycles in FIGS. 3 and 4), step 4 At the third harmonic designated in advance (in this embodiment, from the first harmonic to the fourth harmonic).
FFT operation (Fourier transform) is executed for the ninth order to calculate the third harmonic content.
Note that the third harmonic content may be calculated by a product-sum operation instead of the FFT operation.

Next, in step 5, the content data of the calculation result is compared with the content data (hereinafter referred to as content data) written in an area different from the above-mentioned raw data in the data memory 5. It is determined whether it is large or not (whether it is the past maximum). Then, the content rate of the operation result is stored in the data memory 5.
If the content data is larger than the content data, the process proceeds to step 6 by rewriting (updating) the raw data and content data to the current values in step 6, and directly proceeds to step 7 if not larger. Thus, the digital signal processing circuit 4
Calculates the third harmonic content based on the sampled raw data, and when the content is the highest in the past, updates the raw data and the content data in the data memory 5 respectively. (S in FIGS. 3 and 4) The process from steps 1 to 7 is repeated until the time elapses, and then the process proceeds to step 10.

In FIG. 4, a horizontally extending hatched portion is tertiary content data, which indicates the maximum value at a, and a vertically extending hatched portion indicates the entire raw data when the maximum value a occurs. . The processing by the digital signal processing circuit 4 for the V and W phases (steps 8 and 9) is exactly the same as the processing for the U phase described above. The maximum content data and the raw data at that time are written in the respective data memories 5 (b and c in FIG. 3).

On the other hand, the processing of the CPU 6 will be described.
U6 is the raw data of the maximum content among the raw data written to each phase of the data memory 5 in step 10 out read <br/>, FFT operation using the raw data (Fourier transform) Then, the harmonic content is calculated for each of the first to 49th orders, and the calculation result is displayed on the data analysis display unit 7 in the form of a graph, a table, or the like. Thereafter, in step 11, each data memory 5 is cleared.

Accordingly, the data analysis display section 7 displays the harmonic content from the first to the 49th order when the third harmonic content shows the maximum value for each phase, and the display is 10 minutes. It will be updated with new contents every time. Then, based on the harmonic content displayed on the data analysis display unit 7, the place and time of occurrence are determined, and the cause of the occurrence can be ascertained. The calculated harmonic content can be stored not only on the display but also on a magneto-optical disk or the like.

[0017] According to the harmonic measurement method of this embodiment, U, V, the voltage value of each distribution line L of W phase to continuously sampled with a period of 49.152KH _z by the sensor 1 Therefore, even if a state where the harmonic content of each phase is large occurs for a very short time, it is always detected and used to determine the location and time of occurrence of the harmonic, and the cause of the harmonic generation can be reliably determined. it can.

Next, a second embodiment of the second invention will be described with reference to FIGS. The configuration of the observation device for implementing the harmonic measurement method of this embodiment is exactly the same as that of the first embodiment described above, except for the processing of the digital signal processing circuit 4 and the CPU 6. Therefore, the measurement state of the harmonic by the harmonic observation device will be described with reference to the flowchart of FIG.

In this flowchart, steps 101 to 111 (S101 to S111) are processes performed by the U-phase digital signal processing circuit 4, and steps 112 to 111 are performed.
119 (S112 to S119) are processes performed by the V-phase digital signal processing circuit 4, and step 120 (S120) is W
Processing performed by the digital signal processing circuit 4 of the phase, step 12
1, 122 (S121, S122) are processing performed by the CPU 6.

First, the processing of the U-phase digital signal processing circuit 4 will be described. In step 101, data detected by the sensor 1 is continuously sampled.
Is written to the data memory 5 as raw data. When data for 10 cycles is written in step 103, the third harmonic content is calculated by FFT calculation in step 104,
In step 105, it is determined whether or not the content rate of the calculation result is larger than the content rate data in the data memory 5. When the content rate of the calculation result is large, the raw data and the content rate data are updated in step 106, and an update flag is set in step 107.

Next, at step 108, a processing end flag is set, and at step 109, the process waits until another two-phase processing end flag is set. When all the processing end flags are set in step 109, the update flag and its own processing end flag are reset in step 110, and in step 111, 10 minutes elapse (time S in FIG. 6). After the processing is repeated, the process proceeds to step 121. Therefore, this U-phase digital signal processing circuit 4 has a U-phase like the respective phases of the first embodiment.
The tertiary maximum content that occurred during 10 minutes in the phase and the raw data at that time are written in the data memory 5. A ₁ in FIG. 6 shows the data.

On the other hand, the processing by the V-phase digital signal processing circuit 4 will be described.
Are continuously sampled by the sensor 1 and the data is written to the data memory 5 in step 113. Further, it is determined in step 114 whether or not the update flag is set. If the flag is set, the sampling data (whether or not the content rate is the highest in the past) written in the data memory 5 in step 115 Step 1)
Move to 16. If the update flag has not been set in step 114, the process directly proceeds to step 116.

Next, at step 116, a processing end flag is set. At step 117, when the other two-phase processing end flags are set, the own processing end flag is reset at step 118, and at step 119, 10 minutes elapse. After repeating the processing of steps 112 to 119, the process proceeds to step 121. Therefore, the V-phase digital signal processing circuit 4 writes the V-phase raw data into the data memory 5 when the update flag is set in the U-phase (when the maximum content rate occurs) (b _{1 in} FIG. 6). ).

Step 120 of the W-phase digital signal processing circuit 4 is exactly the same routine as that of the V-phase, and the raw data of the W-phase when the update flag is set in the U-phase is written in the data memory 5. (C _{1 in} FIG. 6). Note that, as in step 109 of the above-described U phase, this step 1
In steps 17 and 120, the next processing is not performed unless the other two-phase processing end flags are set. Accordingly, the processing stages of the respective digital signal processing circuits 4 coincide with each other, and the sampling timing of each phase is synchronized so that sampling is always performed simultaneously.

On the other hand, the processing of the CPU 6 will be described.
U6 reads the raw data (raw data at the maximum content rate of the U phase and raw data of the V phase and the W phase at that time) written in the data memory 5 of each phase in step 121, and reads the raw data. The harmonic content of each order is calculated by FFT calculation, and the calculation result is displayed on the data analysis display unit 7. Thereafter, at step 122, each data memory 5
Clear Therefore, the data analysis display section 7 displays the first harmonic content for the U phase when the third harmonic content shows the maximum value.
The harmonic content from the next to the 49th order is displayed. For the V phase and the W phase, the harmonic content from the 1st to the 49th order when the maximum content occurs in the U phase is displayed. These displays are updated to new contents every 10 minutes.

The period of such harmonic measurement method of the present embodiment is similar to the measuring method of the first embodiment, U, V, 49.152KH the voltage values of the respective distribution line L of W-phase by the sensor 1 _z Since the sampling is performed continuously at each phase, even if a state with a high harmonic content in each phase occurs for a very short time, it is always detected and used to determine the location and time of generation of the harmonic, and The cause of occurrence can be ascertained reliably.

In the present embodiment, the content of the other two phases was calculated when the U phase showed the maximum content. For example, when the V phase or the W phase showed the maximum content, the other content was calculated. The content ratio of two phases may be calculated. Next, a third embodiment of the present invention will be described with reference to FIGS. The configuration of the observation device for performing the harmonic measurement method of this embodiment is exactly the same as that of the first and second embodiments described above, except for the processing of the digital signal processing circuit 4 and the CPU 6. Therefore, the measurement state of the harmonic by this harmonic observation device will be described with reference to the flowcharts of FIGS.

In this flowchart, steps 201 to 215 (S201 to S215) are processes performed by the U-phase digital signal processing circuit 4.
230 (S216 to S230) are processing performed by the V-phase digital signal processing circuit 4, and steps 231 to 245 (S23
1 to S245) are the processes performed by the W-phase digital signal processing circuit 4, and steps 246 to 248 (S246 to S248).
Is a process performed by the CPU 6. As shown in FIG. 11 , the data memory 5 of each phase is divided into a sampling data area 5a and U-phase, V-phase, and W-phase data areas 5b to 5d.

First, the processing of the U-phase digital signal processing circuit 4 will be described. In step 201, data detected by the sensor 1 is continuously sampled, and in step 202
To write as raw data in the sampling data area 5a of the data memory 5. When data for 10 cycles is written in step 203, the third harmonic content is calculated by FFT calculation in step 204, and the content of the calculation result is stored in the U-phase data area 5 of the data memory 5 in step 205.
It is determined whether or not the data is larger than the data of the content rate in b. When the content of the operation result of the character is large and its at step 206
Update the content data and Kino raw data, step 207
Sets the U-phase update flag and proceeds to step 208. If it is not large, the process directly proceeds to step 208.

Further, at step 208, it is determined whether or not the U- phase update flag is set in the V-phase as described later, and if the flag is set, step 209 is executed.
Then, the raw data (regardless of whether or not the content rate is the past maximum) in the sampling data area 5a is written in the V-phase data area 5c. Similarly, in step 210, it is determined whether or not the U- phase update flag is set in the W-phase. If the flag is set, in step 211, the raw data in the sampling data area 5a is written to the W-phase data area 5d. .

Thereafter, the process end flag is set in step 212, and if the other two-phase process end flags are set in step 213, the U-phase update flag and its own process end flag are reset in step 214, and step 215 Until 10 minutes have elapsed (time S in FIG. 10), the processing of steps 201 to 215 is repeated, and then the flow proceeds to step 246. Therefore, the U-phase digital signal processing circuit 4 stores the tertiary maximum content data generated during 10 minutes in the U-phase and the raw data at that time in the data memory 5 in the same manner as each phase of the first embodiment. U-phase data area 5b
And the raw data when the update flag is set in another phase is written to the V-phase or W-phase data area 5c, 5d. In FIG. 10, a ₃ is the data when the content of the U phase is the maximum, a ₂ is the data of the U phase when the content of the V phase is the maximum, and a ₁ is the data when the content of the W phase is the maximum. 2 shows the U-phase data.

On the other hand, the processing of the V-phase digital signal processing circuit 4 will be described. This processing is almost the same as the processing of the U-phase. In steps 221 and 222, the processing for the V-phase which is its own phase is performed. performs processing for the W-phase and U-phase is the other two phases in step 223-226, further, it is differences to reset the V-phase update flag at step 229 (b ₁ in FIG. 10, ~b ₃ ).

Similarly, in the processing of the W-phase digital signal processing circuit, the processing for the W-phase which is its own phase is performed in steps 236 and 237, and the U-phase and the other two phases are processed in steps 238 to 241. performs processing for the V-phase, and further, it is differences to reset the W-phase update flag at step 244 (c ₁ ~c ₃ in FIG. 10). Therefore, for example, when the third-order harmonic content of the U-phase becomes the past maximum at step 205, the maximum content data and the raw data at that time are stored in the U-phase data area 5b of the data memory 5 at step 206. The data is written and updated, and at the same time, the raw data of the V phase at that time is stored in the data memory 5 in step 226.
And the W-phase raw data is written to the U-phase data area 5b of the data memory 5 in step 239.

On the other hand, the processing of the CPU 6 will be described.
U6 determines in step 246 that step 20
U phase content data written in step 6, step 221
V phase content data written in step 23 and step 23
The maximum value is selected from the W-phase content data written in step 6. Then, the raw data (for example, b ₂ ) corresponding to the selected content rate is stored in the data memory 5 in step 247.
And read the raw data (a _2, c ₂ ) at that time from the other two-phase data memory 5, respectively.
The raw data is FFT-calculated to calculate the harmonic content of each order, and the calculation result is displayed on the data analysis display unit 7. Thereafter, in step 248, each data memory 5 is cleared.

Accordingly, the data analysis display section 7 displays the harmonic content from the first to the 49th order for the phase in which the third harmonic content has the maximum value.
For the phase, the harmonic content from the first to the 49th when the maximum content occurs is displayed. These displays are updated to new contents every 10 minutes.

As described above, in the harmonic measuring method of the present embodiment, the voltage value of each of the U, V, and W phase distribution lines L is measured by the sensor 1 at 49.152 KH, similarly to the measuring methods of the first and second embodiments. _Since sampling is performed continuously at the cycle of _z , even if a state where the harmonic content is large in each phase occurs for a very short time, it is always detected and used to determine the location and time of occurrence of the harmonic, The cause of generation of harmonics can be ascertained reliably.

The present invention is not limited to the above embodiments. For example, in each of the above embodiments, the harmonic content was determined based on the voltage value detected by the sensor 1.
The harmonic content may be determined based on the current value. or,
In the embodiments described above the sampling frequency and 49.152KH _z, has been displaying the new data to the display of the data analysis display unit 7 for each 10min, it may change the display period of the sampling frequency and data analysis display section 7 .

Further, in the above embodiment, the raw data is selected by calculating the content only for the third harmonic, but the content is calculated for a plurality of orders or the content is calculated for all the orders. Raw data may be selected.

[0039]

As described above in detail, according to the harmonic measuring method of the present invention, an excellent effect that harmonics can always be accurately measured is exhibited.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining processing of an observation device according to a first embodiment.

FIG. 2 is a block diagram illustrating an electrical configuration of the observation device.

FIG. 3 is a timing chart showing a sampling situation.

FIG. 4 is a diagram showing a relationship between raw data and content data.

FIG. 5 is a flowchart for explaining processing of the observation device of the second embodiment.

FIG. 6 is a timing chart showing a sampling situation.

FIG. 7 is a flowchart illustrating a process performed by the observation device according to the third embodiment.

FIG. 8 is a flowchart illustrating a process performed by the observation device according to the third embodiment.

FIG. 9 is a flowchart for explaining processing of the observation device of the third embodiment.

FIG. 10 is a timing chart showing a sampling situation.

FIG. 11 is a diagram showing a storage area of a data memory.

FIG. 12 is a block diagram showing an electrical configuration of a conventional observation device.

FIG. 13 is a timing chart showing a sampling situation.

[Explanation of Signs] L Distribution line as electric wire

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsuro Ishihara 1st character small needle in Inuyama City, Aichi Prefecture Energy Support Co., Ltd. (72) Inventor Fumiaki Kawano 1st character small needle in Inuyama City, Aichi Prefecture Energy Support Corporation ( 72) Inventor Yasuhiro Tanahashi No. 1 Kamikobari, Inuyama-shi, Aichi Energy Support Co., Ltd. (56) References JP-A-56-84565 (JP, A) JP-A-59-70970 (JP, A) 2-17822 (JP, A) JP-A-56-168564 (JP, A) JP-A-57-182656 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 23/20 H02J 13/00 301

Claims (3)

(57) [Claims] An AC voltage value or a current value flowing through an electric wire is continuously sampled, and raw data obtained when the content of harmonics of a predetermined order specified in advance is the maximum from the sampled data is obtained. Select and raw data at that time
Harmonic measurement wherein the this <br/> for calculating a relative harmonic content of each order, respectively, based on the. 2. A three-phase alternating current voltage value or a current value flowing through an electric wire is continuously sampled for each phase, and a predetermined phase is specified from among the sampled data.
When the constant, predetermined order harmonic content is the largest
Raw data is selected and the predetermined order of one phase is selected.
The raw data of the other two phases at the time when the harmonic content of the maximum value is the maximum value is selected, and each raw data is selected based on the raw data of each phase at that time.
A harmonic content calculating method for calculating the harmonic content of each number . 3. A three-phase voltage or current value of a three-phase alternating current flowing through an electric wire is continuously sampled for each phase, and a predetermined value is specified for each phase from the sampled data.
With Sadaji number of harmonic content of elect each raw data when the maximum, the predetermined order harmonic content of each phase selected raw data of another two-phase when the maximum value Then, the highest harmonic content of each phase is compared to select the raw data of the highest content and the raw data of the other two phases at that time, based on the raw data of each phase at that time. Each order
A harmonic content measuring method for calculating the harmonic content .