TW201337531A - Voltage monitoring device and method - Google Patents

Abstract

This invention is to provide a voltage monitoring device and a voltage monitoring method capable of not only detecting a transient voltage drop, but also obtaining the information related to voltage change before and after the transient voltage drop. A power sensor (1) has a voltage monitoring function. The power sensor (1) comprising: a measuring unit (10) for measuring AC voltages of the site to be measured and for detecting transient voltage drop generated at the site to be measured; and a memory unit (19). The measuring unit (10) generates a first record data related to all AC voltage elapses occurred at a first time interval during the first time period up until the time point when the transient voltage drop is detected, and a second record data related to all AC voltage elapses occurred at a second time interval after the time point of detecting the transient voltage drop, and the first record data and the second record data are stored in the memory unit (19). The second time interval is shorter than the first time interval, thereby obtaining voltage-related details of the transient voltage drop.

Description

Voltage monitoring device and voltage monitoring method

The present invention relates to a voltage monitoring device and a voltage monitoring method for monitoring instantaneous voltage drop and instantaneous power failure.

An instantaneous voltage drop or an instantaneous power failure can greatly affect the operation of equipment, devices, and the like that are sensitive to variations in the power supply voltage. For example, in the manufacture of a semiconductor device, fine processing is required, and thus it is necessary to precisely control the manufacturing apparatus. An instantaneous voltage drop or an instantaneous power outage has the potential to have a significant impact on the operation of the manufacturing device. Therefore, up to now, techniques for monitoring instantaneous voltage drop or instantaneous power failure have been proposed.

For example, Japanese Patent Publication No. Hei 11-51985 (Patent Document 1) discloses a calculation processing device for detecting power failure and re-powering (recovering power supply) of an AC power supply to a driving power supply of a microcomputer. The device includes an A/D (analog/digital) converter that converts an instantaneous voltage of an alternating current power source into a digital value, a comparator that determines whether the digital value is equal to or lower than a set value, and a length that falls within a period equal to or less than a set value according to the digital value. A detection processing unit for detecting a power failure. When a power failure is detected, the operating clock frequency of the CPU (Central Processing Unit) is lowered to a lower frequency than usual. When the re-power is detected, the operating clock frequency of the CPU is returned to the normal frequency.

[Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 11-51985

The calculation processing device disclosed in Patent Document 1 is intended to detect a phenomenon of power failure and re-power. As mentioned above, in the factory, an instantaneous power outage or occurrence does not result in In the case of a voltage drop at the moment of power failure, the production process is greatly affected. In order to analyze and formulate the phenomenon of instantaneous power failure and instantaneous voltage drop, it is preferable to obtain as much detailed information as possible about the change in voltage before and after the occurrence of the phenomenon. However, Patent Document 1 does not describe a specific method for obtaining such information.

An object of the present invention is to provide a voltage monitoring device and a voltage monitoring method capable of acquiring not only information about a transient voltage drop but also information relating to a voltage change before and after a transient voltage drop occurs.

According to an aspect of the present invention, a voltage monitoring device includes: a measuring unit that measures an AC voltage of a measurement portion, detects an instantaneous voltage drop occurring at a measurement portion, and a memory portion. The measurement unit generates the first history data and the second history data, and stores the first history data and the second history data in the memory unit. The first history data refers to the time until the detection time of the instantaneous voltage drop. The data related to the transition of the AC voltage appearing at the first time interval in one period, and the second history data indicating the transition of the AC voltage appearing at the second time interval after the detection time point of the instantaneous voltage drop . The second time interval is shorter than the first time interval.

According to this configuration, the measurement unit detects the instantaneous voltage drop of the measurement site. The measurement unit generates first history data related to the transition of the AC voltage in the first period up to the detection time point at which the voltage is dropped. The measurement unit further generates the second history data after the detection time point of the instantaneous voltage drop. Since the transition of the AC voltage at a small time interval is indicated in the second history data, detailed information relating to the voltage fluctuation after the detection of the instantaneous voltage drop can be obtained. The first history data and the second history data are memorized in the memory unit. Therefore, it is possible to obtain information relating to voltage fluctuations in a period before and after the detection time point of the instantaneous voltage drop.

"Instantaneous voltage drop" includes two meanings of an instantaneous power failure and an instantaneous voltage drop that does not cause a power outage.

The timing system in which the first history data is stored in the memory unit may be detected before the instantaneous voltage drop is detected or after the instantaneous voltage drop is detected. In many cases, the point in time at which an instantaneous voltage drop occurs cannot be predicted. Therefore, for example, the first history data may be memorized in the memory unit, and the material may be updated at a certain time interval. Alternatively, the measurement unit may store the first history data in advance, and write the data to the memory unit when the instantaneous voltage drop is detected.

Preferably, the measurement unit further generates waveform data of the AC voltage after detecting the instantaneous voltage drop, and stores the waveform data of the generated AC voltage in the memory unit.

According to this configuration, it is possible to obtain more detailed information relating to the transition of the voltage after the detection of the instantaneous voltage drop. For example, the voltage waveform after the instantaneous voltage drop can be detected based on the waveform data stored in the memory unit.

Preferably, the first history data includes: a first data acquired for each first period of the alternating voltage during the first period; and a second period until a detection time point of the instantaneous voltage drop The second data obtained for each second cycle of the alternating voltage. The second history data includes: a third data acquired for each third period of the alternating voltage during a third period shorter than the first period. The first time interval corresponds to the first period. The second time interval corresponds to the third period. The second period is shorter than the first period.

According to this configuration, it is possible to obtain the detailed information of the voltage in the period from the time when the instantaneous voltage drop is detected immediately to the time when the instantaneous voltage drop is detected, based on the second data and the third data. News. It is also possible to obtain, based on the first data, information relating to a general trend of the voltage before the detection of the instantaneous voltage drop.

Preferably, the period in which the measurement unit acquires the waveform data is shorter than the third period.

According to this configuration, the size of the waveform data can be controlled. Thereby, for example, the memory capacity of the memory unit can be saved. Further, the writing time of writing data to the memory unit can be shortened. The power supply voltage of the voltage monitoring device is likely to be affected by an instantaneous voltage drop. By shortening the writing time, it is possible to increase the probability that the waveform data can be retained in the memory.

Preferably, the first period corresponds to a complex period of the alternating voltage. The second period and the third period correspond to one cycle of the alternating voltage. The first data is the sum of the squares of the instantaneous values of the voltage during the period of the complex period. The second data and the third data represent the sum of the squares of the instantaneous values of the voltages during one cycle of the alternating voltage.

According to this configuration, it is possible to shorten the time required for the measurement unit to generate data related to the voltage effective value. Usually, in order to obtain an effective value, an average value of the sum of squares of voltage instantaneous values within a prescribed period (for example, one period) is calculated, and the square root of the average value is calculated. However, the calculation of the square root may take time. According to the above configuration, the calculation of the square root is omitted, and therefore, the generation time of the data can be shortened.

Preferably, the measurement unit generates the monitoring data by generating a square sum of the instantaneous values of the voltages during a half cycle of the alternating voltage, and compares the transition of the monitoring data with the set mode to detect the instantaneous voltage drop. .

According to this configuration, the time required to generate the monitoring material can be shortened. Thereby, the instantaneous voltage drop can be detected quickly.

Preferably, the set mode is selected from the plural mode. Voltage monitoring device is further The alarm output unit includes an alarm corresponding to the set mode from the plurality of alarms corresponding to the complex mode when the instantaneous voltage drop is detected.

According to this configuration, the alarm can be made different depending on the mode of the instantaneous voltage drop. Preferably, the memory unit non-volatilely memorizes the first history data and the second history data.

According to this configuration, it is possible to prevent the generated first history data and the second history data from disappearing.

According to another aspect of the present invention, a voltage monitoring method includes: a detecting step of measuring an alternating voltage of a measuring portion to detect an instantaneous voltage drop generated in the measuring portion; and generating a first step of generating the first history data The history data, the first history data refers to data related to the transition of the AC voltage occurring at the first time interval in the first period until the detection time point of the instantaneous voltage drop; the generation of the voltage drop at the moment The step of detecting the data after the time point; the step of remembering to memorize the generated data in the memory. The data generated after the detection time point includes a second history data indicating the transition of the AC voltage appearing at the second time interval. The second time interval is shorter than the first time interval. In the step of remembering, the memory department memorizes the first resume data and the second resume data.

According to this configuration, it is possible to obtain information on the fluctuation of the voltage in the period before and after the detection time point of the instantaneous voltage drop. In addition, the memory unit can also memorize the first history data and the second history data after the detection time point of the instantaneous voltage drop. Alternatively, the memory unit may memorize the first history data before the detection time point of the instantaneous voltage drop, and memorize the second history data after the detection time point of the instantaneous voltage drop.

Preferably, the data generated after the detection time point includes waveform data of the AC voltage after detecting the instantaneous voltage drop. In the memory step, the memory department further memorizes the waveform data.

According to this configuration, it is possible to obtain more detailed information related to the transition of the voltage after the detection of the instantaneous voltage drop.

Preferably, the first history data includes: first data, which is data acquired for each first period of the alternating voltage during the first period; and second data, which is until the instantaneous voltage drop is detected. The data acquired for each second cycle of the AC voltage during the second period up to the time point. The second history data includes third material, which is data acquired for each third period of the alternating voltage during a third period that is shorter than the first period. The first time interval corresponds to the first period, the second time interval corresponds to the third period, and the second period is shorter than the first period.

According to this configuration, it is possible to acquire, based on the second data and the third data, detailed information of the voltage in a period from the time when the instantaneous voltage drop is detected to the time when the instantaneous voltage drop is detected. Further, based on the first data, information relating to the general trend of detecting the voltage before the instantaneous voltage drop can be obtained.

Preferably, the period during which the waveform data is generated is shorter than the third period.

According to this configuration, the size of the waveform data can be controlled.

Preferably, the first period corresponds to a complex period of the alternating voltage. The second period and the third period correspond to one cycle of the alternating voltage. The first data is the sum of the squares of the instantaneous values of the voltage during the period of the complex period. The second data and the third data represent the sum of the squares of the instantaneous values of the voltages during one cycle of the alternating voltage.

According to this configuration, it is possible to shorten the time required for the measurement unit to generate data related to the voltage effective value.

Preferably, in the detecting step, the monitoring data is generated by generating a sum of squares of voltage instantaneous values during a half cycle of the alternating voltage, and the monitoring data is shifted and the set mode is set. Compare the equations to detect transient voltage drops.

According to this configuration, the time required to generate the monitoring material can be shortened. Thereby, the instantaneous voltage drop can be detected quickly.

Preferably, the set mode is selected from the plural mode. The voltage monitoring method further includes a step of outputting an alarm, and in the step of outputting the alarm, when detecting an instantaneous voltage drop, an alarm corresponding to the set mode is output from the plurality of alarms respectively corresponding to the complex mode.

According to this configuration, the alarm can be made different depending on the mode of the instantaneous voltage drop. Preferably, the memory unit non-volatilely memorizes the first history data and the second history data.

According to this configuration, it is possible to prevent the generated first and second history data from disappearing.

According to the present invention, not only the instantaneous voltage drop but also the information relating to the voltage change before and after the transient voltage drop occurs can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same or corresponding portions in the drawings are denoted by the same reference numerals and will not be repeatedly described.

Fig. 1 is a view showing an embodiment of a voltage monitoring device according to the present invention. Referring to Fig. 1, in the present embodiment, a voltage monitoring device according to the present invention is realized as a power sensor 1. The power sensor 1 measures the voltage and current of the measurement portion of the AC circuit 5.

The electric equipment 2 in the area outputs the electric power received via the power line 2a to the alternating current circuits 5, 9. The electrical equipment 2 in the area includes power substation, distribution board, switchboard and regional trunk.

The AC circuit 5 supplies AC power to the load device 6. The load device 6 is, for example, a device or device in a factory. An auxiliary power source 8 is connected to the AC circuit 5. The auxiliary power supply 8 is the load device 6 The backup power supply, for example, UPS (Uninterruptible Power Supply).

The AC circuit 5 includes power lines 5a, 5b, 5c. FIG. 1 shows a three-phase three-wire type as an example of a power distribution method of the AC circuit 5. The power distribution mode of the AC circuit 5 is not limited to a three-phase three-wire type, and may be, for example, a single-phase two-wire type, a single-phase three-wire type, or a three-phase four-wire type.

The power sensor 1 receives the power supply voltage via the AC circuit 9. The AC circuit 9 is connected to the auxiliary power source 3. The auxiliary power source 3 is a backup power source of the power sensor 1, such as a UPS. However, the auxiliary power source 3 is not a necessary device.

The measurement portion of the power sensor 1 is associated with a portion that transmits AC power between the AC circuit 5 and the load device 6. Specifically, the power sensor 1 is connected to the power lines 5a, 5b, and 5c, and the voltage of the AC circuit 5 is measured. Further, the current transformers 1a and 1b are connected to the power sensor 1 . The current transformers 1a, 1b detect the currents flowing on the power lines 5a, 5b, respectively. The power sensor 1 measures the current of the measurement portion based on the signals output from the current transformers 1a and 1b.

The electricity sensor 1 calculates the amount of electricity in the measurement site based on the measured voltage and the measured current. The amount of electric power obtained by calculation is not limited to the power consumption of the load device 6. For example, the load device 6 may have a motor, and when the motor performs a regeneration operation, the amount of electric power generated by the motor is obtained.

When an electric power device of an electric power supplier (electric power company or the like) has an accident due to, for example, a lightning strike, the accident equipment is cut off from the electric power system. In this case, the voltage of the electric equipment 2 and the alternating current circuits 5, 9 in the area may be lowered in a short period of time. This voltage drop is called "instantaneous voltage drop." In addition, in the above case, an instantaneous power failure may occur. This power outage is called "instantaneous power outage." In the present embodiment, the term "instantaneous voltage drop" includes both the instantaneous power failure and the instantaneous voltage drop that does not cause a power failure.

The power sensor 1 monitors the AC voltage of the measurement site and detects an instantaneous voltage drop occurring at the measurement site. The power sensor 1 detects an instantaneous voltage drop by comparing a mode of the measured voltage transition with a previously set mode. In this case, the power sensor 1 outputs a signal (alarm output) for generating an alarm to the alarm device 4. The alarm device 4 issues an alarm based on the alarm output from the power sensor 1. The alarm device 4 is, for example, a lamp, a buzzer, or the like, but is not limited thereto.

The power sensor 1 also generates history (record) data relating to the transition of the AC voltage of the AC circuit 5, and stores the history data. When the power sensor 1 detects an instantaneous voltage drop, the history data is stored in the power sensor 1 . The history data stored in the power sensor 1 is sent to the data processing device 7 at an appropriate timing. The power sensor 1 transfers data to the material processing device 7 via, for example, a communication device and a communication line omitted in the drawing. The data processing device 7 is realized by, for example, a personal computer that executes a predetermined program.

The power sensor 1 not only memorizes data related to the voltage transition, but also memorizes other data such as power-related data. In addition, the power sensor 1 can also record data in a recording medium such as a memory card. The recording medium is taken out from the power sensor 1 and inserted into the material processing device 7. The data processing device 7 reads the power amount data stored in the recording medium. Data can also be transferred from the power sensor 1 to the data processing device 7 by this method.

Fig. 2 is a block diagram showing the configuration of a main part of a power sensor according to an embodiment of the present invention. Referring to Fig. 2, power sensor 1 includes measurement unit 10, communication control unit 13, connection unit 14, signal path 15 including isolator 15a, power supply circuit 16, memory unit 19, capacitor 20, and semiconductor relay 21.

The measurement unit 10 includes a voltage measurement unit 11 , a current measurement unit 12 , and a calculation circuit 18 . Voltmeter The measuring unit 11 includes a voltage dividing circuit 11a and an A/D converting circuit 11b. The current measuring unit 12 includes current transformers 1a and 1b, a current/voltage converting circuit 12a, and an A/D converting circuit 12b. It is also possible to integrate the A/D conversion circuits 11b, 12b into one circuit. Alternatively, the A/D conversion circuits 11b, 12b and the calculation circuit 18 may be integrated into one processing device (for example, a CPU). Further, the communication control unit 13 can also be realized by, for example, a CPU.

The voltage measuring unit 11 measures the voltages Va, Vb, and Vc of the power lines 5a, 5b, and 5c. The voltage dividing circuit 11a divides the input voltages (voltages Va, Vb, and Vc) to generate a voltage suitable for the measured strength. The A/D conversion circuit 11b performs sampling and A/D conversion on the voltage output from the voltage dividing circuit 11a. Thereby, digital data indicating the respective values of the voltages Va, Vb, and Vc is generated.

The current measuring unit 12 measures the currents I1 and I3 of the power lines 5a and 5b. The converter 1a outputs a current I1a that is proportional to the current I1. The converter 1b outputs a current I3a that is proportional to the current I3. The current/voltage conversion circuit 12a converts the currents I1a, I3a into voltages and amplifies the voltages. Thereby, the current/voltage conversion circuit 12a generates a voltage suitable for the measured strength. The A/D conversion circuit 12b performs sampling and A/D conversion on the voltage output from the current/voltage conversion circuit 12a. Digital data representing the respective values of the currents I1, I3 is thus generated.

The calculation circuit 18 generates digital data indicating the value of the current I2 flowing through the power line 5c based on the digital data from the current measurement unit 12 indicating the respective values of the currents I1 and I3. Since the currents I1, I2, and I3 are zero in total, the value of the current I2 can be calculated from the values of the currents I1 and I3. The calculation circuit 18 calculates the amount of electric power of the measurement portion by using the digital data of the voltages Va, Vb, and Vc output from the voltage measurement unit 11 and the digital data of the currents I1 to I3. The calculation circuit 18 stores the electric energy data as a calculation result in the memory unit 19.

The calculation circuit 18 further generates history data (first history data) related to the transition of the voltages Va, Vb, and Vc, and stores the history data in the memory unit 19. As will be described later in detail, the calculation circuit 18 stores the history data of the predetermined period in the memory unit 19. The calculation circuit 18 updates the first history data stored in the memory unit 19 based on the latest data related to the voltage. Further, the first history data may be stored in the calculation circuit 18 (for example, Cache: cache memory) until the instantaneous voltage drop is detected.

The calculation circuit 18 further generates monitoring data for monitoring the respective voltages Va, Vb, Vc. The calculation circuit 18 compares the transition of the monitoring data with the set mode to detect the instantaneous voltage drop. When the instantaneous voltage drop is detected, the calculation circuit 18 generates the second history data related to the detection of the transition of the voltages Va, Vb, and Vc after the instantaneous voltage drop, and stores the second history data in the memory unit 19. .

The first history data indicates the transition of the alternating voltage that occurs at the first time interval. In contrast, the second history data indicates the transition of the AC voltage appearing at the second time interval. The second time interval is shorter than the first time interval. That is, after the instantaneous voltage drop is detected, data indicating the fine transition of the AC voltage is generated. The calculation circuit stores the second history data in the memory unit 19.

If necessary, the data stored in the memory unit 19 is read by the calculation circuit 18, and the data is transmitted to the communication control unit 13. The communication control unit 13 outputs the material to the outside via the connection unit 14.

When the calculation circuit 18 detects an instantaneous voltage drop, the calculation circuit 18 outputs a detection signal. This signal is transmitted to the communication control unit 13 via the signal path 15. The communication control unit 13 causes the semiconductor relay 21 to operate in response to the detection signal. In this case, the semiconductor relay 21 outputs a signal (alarm output) for generating an alarm to the alarm device 4.

The signal path 15 is provided between the calculation circuit 18 and the communication control unit 13. In signal path 15 An isolator 15a is provided on the way. The isolator 15a insulates the calculation circuit 18 from the communication control unit 13. When the voltage value and the current value of the AC circuit 5 are high, the voltage measuring unit 11 and the current measuring unit 12 may become high voltage circuits. In order to transmit a signal while ensuring electrical insulation with respect to the high voltage portion, an isolator 15a as a signal insulating portion is provided. The isolator 15a is, for example, a capacitive digital isolator. Further, the signal insulating portion can also be realized by, for example, a photocoupler.

The connection portion 14 is for performing data communication between the power sensor 1 and other devices. Although omitted from the drawings, the connecting portion 14 is constituted by a connector for connecting, for example, a bus bar and a communication line. For example, the power sensor 1 receives data of the amount of electric power calculated by another power sensor (omitted from the drawing) via the connection unit. The power sensor 1 can output the calculated power amount data by the power sensor 1 via the connection portion 14.

The power supply circuit 16 converts a power supply voltage (AC voltage) from the outside into a DC voltage, and supplies the DC voltage to each module of the power sensor 1 . The capacitor 20 is charged by a DC voltage from the power supply circuit 16. When an instantaneous voltage drop occurs, the capacitor 20 is used as a backup power source. The capacitor 20 is, for example, an electric double layer capacitor. Instead of a capacitor, for example, a secondary battery can be used as a backup power source.

The data can be written to the memory unit 19, and the memory unit 19 can memorize the written data non-volatilely. For example, FeRAM (Ferroelectric Random Access Memory) is used as the memory unit 19. In addition to non-volatile features, FeRAM has features that do not require deletion time and write latency, and also features features such as many read and rewrite times, features of low power consumption, and the like. By using the FeRAM as the memory unit 19, a lot of data can be written into the memory unit 19 in a short time. In addition, it can also be separated from the memory unit 19 A memory unit for storing power data is set uniquely.

FIG. 3 is a flow chart showing the voltage monitoring process performed by the power sensor 1 shown in FIGS. 1 and 2. Referring to Fig. 2 and Fig. 3, in step S1, the calculation circuit 18 sets the detection mode based on, for example, an instruction from the user. The number of modes set can be plural or one.

The detection mode includes a voltage level (reference value) for detecting a voltage drop and a time period during which the voltage level is maintained. For example, the complex detection mode is memorized in the memory unit 19 in advance, and the calculation circuit 18 can read at least one of the complex detection modes.

In step S2, information relating to the presence or absence of the auxiliary power source 3 (refer to FIG. 1) is set to the calculation circuit 18, for example, according to an instruction from the user.

In step S3, the calculation circuit 18 generates data related to the instantaneous voltage using the instantaneous value of the voltage (A/D value) obtained by the sampling and A/D conversion by the A/D conversion circuit 11b, and The data is temporarily stored in the memory unit 19. This information includes first resume data and surveillance data. The first history data is stored in the memory unit 19.

The first resume data includes the first data and the second data. The first data is the data obtained for each first cycle of the alternating voltage during the first period. The second data is the second data acquired for each second period of the alternating voltage in the second period up to the detection time point of the instantaneous voltage drop.

For example, the first data is the sum of the squares of the instantaneous values of the voltages taken for every ten cycles of the AC in ten seconds. The sum of squares is the average of the sum of the squares of the unit periods of ten cycles, wherein the sum of the squares of the unit periods is the sum of the squares of the instantaneous values of the voltages obtained for each cycle of the alternating current. Therefore, the "first period" described above is ten seconds, and the "first period" is ten cycles of the alternating current waveform. In addition, the "first cycle" corresponds to the "first time interval" of the first history data.

For example, the second data is the sum of the squares of the instantaneous values of the voltages taken for each cycle of the exchange in one second. Therefore, the "second period" described above is one second, and the "second period" is one period of the alternating current waveform.

In addition, the first period and the second period are always updated until an instantaneous voltage drop is detected. The end point of the first period and the end point of the second period are the time points for obtaining the latest first data and second data. The starting point of the first period is the time point ten seconds before the time point when the latest first data is acquired, and the starting point of the second period is one second before the time point of obtaining the latest second data. Time point.

In step S4, the calculation circuit 18 generates the sum of squares by using the A/D value in the period corresponding to 0.5 cycle of the alternating current waveform until the latest A/D value is obtained. The value of this sum of squares is used as monitoring data for detecting an instantaneous voltage drop. The calculation circuit 18 compares the monitoring data with the setting mode.

In step S5, the calculation circuit 18 determines whether or not the mode of the transition of the voltage indicated by the monitoring data matches the setting mode. When the mode of the transition of the voltage indicated by the monitoring data does not match the setting mode, the calculation circuit 18 determines that the instantaneous voltage drop has not occurred. In this case (NO in step S5), the process returns to step S3. On the other hand, when the mode of the transition of the voltage indicated by the monitoring data matches the setting mode, the calculation circuit 18 determines that the instantaneous voltage drop has occurred. In this case (YES in step S5), the process proceeds to step S6.

Further, when the complex detection mode is set in step S1, in step S4, the monitoring data system compares each of the plurality of setting modes. Then, in step S5, in the case where at least one of the mode of monitoring the transition of the data coincides with at least one of the plural setting modes, proceeding to step The processing of step S6.

In step S6, the calculation circuit 18 outputs a detection signal indicating that the instantaneous voltage drop is detected. This detection signal differs depending on the set detection mode. For example, the frequency of different detection signals can also be set according to the detection mode. In the case where the detection signal is a pulse signal, the duty ratio of the different signals may be set according to the detection mode. The communication control unit 13 receives the detection signal and controls the semiconductor relay 21 in response to the detection signal. Thereby, the semiconductor relay 21 generates an alarm output. Since the detection signal differs depending on the set detection mode, the alarm output differs depending on the set detection mode.

In step S7, the calculation circuit 18 determines whether or not the auxiliary power source 3 is present. This determination is made based on the setting of the calculation circuit 18 in step S2. When the auxiliary power supply 3 is present (YES in step S7), the process proceeds to step S8. On the other hand, when there is no auxiliary power supply 3 (NO in step S7), the process proceeds to step S10.

In step S8, the calculation circuit 18 generates second history data and waveform data indicating an alternating current waveform. In step S9, the calculation circuit 18 stores the second history data and the waveform data in the storage unit 19.

The second resume data includes third material that is data obtained for each third period of the alternating voltage during a third period that is shorter than the first period. For example, the "third period" is one second, and the "third period" is one cycle of communication. In particular, the calculation circuit 18 generates a sum of squares of voltage instantaneous values for each cycle of the AC waveform. The third data is the value of the sum of squares. The "third period" corresponds to the "second time interval" in the second history data.

The calculation circuit 18 further utilizes the voltage instantaneous value to generate waveform data after detecting the instantaneous voltage drop. Generate five cycles of waveform data for the exchange. Calculation circuit 18 will be the third capital The material and waveform data are stored in the memory unit 19.

The length of the third period described above is not particularly limited. For example, the third period may be a certain period of time from the point in time when the instantaneous voltage drop is detected. Alternatively, the third period may be a period from when the instantaneous voltage drop is detected to when the voltage is restored. Alternatively, the third period is set to a shorter one of the predetermined period and the voltage recovery period.

When there is no auxiliary power supply (NO in step S7), the process proceeds to step S10. In step S10, the calculation circuit 18 is converted into the energy saving mode. In the energy saving mode, for example, power supplied to modules other than the measurement unit 10 and the memory unit 19 is reduced as much as possible. Preferably, power supply to the modules other than the measurement unit 10 and the memory unit 19 is stopped.

Next, in step S11, the calculation circuit 18 generates second history data and waveform data indicating an alternating current waveform. In step S12, the calculation circuit 18 stores the second history data and the waveform data in the storage unit 19. Since the processing of steps S11 and S12 is the same as the processing of steps S8 and S9, respectively, the description will not be repeated. The third period in this case may be, for example, a certain period from the detection time point of the instantaneous voltage drop, or a period from the time when the instantaneous voltage drop is detected to the voltage recovery, or two periods. A shorter period of time.

4 is a diagram for explaining an example of a detection mode. Referring to Figure 4, each mode includes voltage levels and durations. Mode 1 corresponds to the case where the voltage level of the original voltage level below VL1 (%) lasts for t1 (seconds). In mode 2, the voltage level is defined as VL2 (%) of the original voltage, and the duration is defined as t2 (second). In mode 3, the voltage level is defined as VL3 (%) of the original voltage, and the duration is defined as t3 (second). VL1>VL2>VL3, t1>t2>t3. That is, the more the voltage drops, the shorter the duration for detecting the voltage drop as the instantaneous voltage drop.

The mode shown in FIG. 4 may be set based on a specific standard or may be arbitrarily set. As an example, the mode can be set based on the "SEMI F47" standard.

FIG. 5 is a diagram for explaining a method of generating monitoring data. Referring to Fig. 5, first, the calculation circuit 18 obtains A/D values V ₁ , V ₂ , V ₃ , V ₄ ... V _n1 of the AC voltage 30 during a period of one-half cycle (T/2). To calculate the sum of squares (V ₁ ² + V ₂ ² + V ₃ ² + V ₄ ² + ... + V _n1 ² ). Further, since the sampling frequency is constant, the number n1 of A/D values in the half cycle of the AC voltage can be obtained in advance.

The calculation circuit 18 determines the voltage level using the square sum and the reference value described above. This reference value can be obtained in advance by multiplying the square of the case where the voltage is normal by the voltage level shown in FIG.

The calculation circuit 18 compares the reference value with the sum of squares (V ₁ ² + V ₂ ² + V ₃ ² + V ₄ ² + ... + V _n1 ² ). Next, each time the A/D value is obtained from the A/D conversion circuit 11b, the calculation circuit 18 compares the reference value and the square sum. At this time, the calculation circuit 18 discards the earliest (old) square value (= V ₁ ² ) of the original square sum, and adds the latest square value. Therefore, the square sum obtained next is (V ₂ ² + V ₃ ² + V ₄ ² + ... + V _n1 ² + V _n2 ² ). The calculation circuit 18 compares the sum of squares ((V ₂ ² + V ₃ ² + V ₄ ² + ... + V _n1 ² + V _n2 ² ) with a reference value.

Thereafter, likewise, the calculation circuit 18 compares the sum of squares (x ₃ ² + x ₄ ² + ... + x _n1 ² + x _n2 ² + x _n3 ² ) with the reference value, followed by the sum of squares (x ₄ ² +...+x _n1 ² +x _n2 ² +x _n3 ² +x _n4 ² ) Compare with the reference value. In this manner, the calculation circuit 18 always compares the sum of squares of one-half of the period up to the latest time point with the reference value. The time interval for monitoring the instantaneous voltage drop is substantially equal to the sampling interval of the A/D value.

The effective value is the square root of the mean of the sum of the squares. However, it takes time to calculate the square root. Therefore, the calculation circuit 18 calculates an effective value, and uses the effective value to detect the instantaneous voltage drop. At this time, the time point at which the instantaneous voltage drop is detected may be delayed. In the present embodiment, the calculation of the square root is omitted by comparing the square sum with the reference value. Thereby, it is possible to prevent the time point delay in detecting the instantaneous voltage drop.

In the present embodiment, the instantaneous voltage drop is also calculated based on the sum of the squares of the instantaneous values acquired during one-half of the period (T/2) of the alternating current. The effective value is usually calculated from the instantaneous value obtained during the period of one cycle of the alternating current. In the case of an AC waveform, the waveform on the substantially positive side is the same as the waveform on the negative side. Thereby, the sum of the squares of the instantaneous values acquired in the period of one-half cycle (T/2) of the alternating current is used as the monitoring data. Thereby, since the calculation time of the monitoring data can be prevented from becoming long, it is possible to prevent the time point delay in detecting the instantaneous voltage drop.

Fig. 6 is a view for explaining a procedure of generating and storing data before detecting an instantaneous voltage drop. Referring to Fig. 6, the calculation circuit 18 generates a square sum 41 for each cycle based on the instantaneous value of the voltage obtained by sampling and A/D conversion during one period T of the alternating current voltage 30. The sum of squares of one cycle 41 is accumulated in the buffer 40 of the memory unit 19. If a sum of squares of ten cycles is generated 41, the calculation circuit 18 calculates an average of ten cycles of the sum of squares 41.

The calculation circuit 18 stores the average value in, for example, the buffer 42 of the memory unit 19. The buffer 42 has a ring buffer structure composed of x buffers B ₁ , B ₂ , ..., B _x-2 , B _x-1 , and B _x . The buffers B ₁ , B ₂ , ..., B _x-2 , B _x-1 , and B _x respectively hold the average values A ₁ , A ₂ , ..., A _x-2 , A _x-1 , and A _x . The count values C ₁ , C ₂ , ..., C _x-2 , C _x-1 , C _x are assigned to the buffers B ₁ , B ₂ , ..., B _x-2 , B _x-1 , B _{x , respectively.} . Based on these count values, a buffer in which the latest average value is stored is determined. For example, stored in the buffer B ₁ at the latest average value, the order from the earliest (old) is the average value A ₂ arranged starting averaged to update the average value of _{A x-2, A x-} 1, A The order of _x and A ₁ .

Thereafter, likewise, the calculation circuit 18 calculates the sum of squares for one cycle and stores the sum of the squares in the buffer 40. If the sum of the squares of the next ten cycles is stored in the buffer 40, the calculation circuit 18 calculates the average of the sum of the squares of the ten cycles, and stores the average value in the buffer 42. In the above example, the oldest (old) average value A _{2 is} stored in the buffer B ₂ . Therefore, the calculation circuit 18 saves the latest average value in the buffer B ₂ .

The buffer 40 is configured to hold, for example, at least the sum of squares for each period in one second (i.e., the sum of squares of the same number as the frequency of the alternating voltage 30). Thereby, all the square sums for each cycle in one second up to the latest time point are stored in the buffer 40.

In the case where the calculation circuit 18 detects an instantaneous voltage drop, the calculation circuit 18 calculates the sum of squares for each cycle (one second) stored in the buffer 40 and the square of the ten cycles stored in the buffer 42. The average value of the sum (ten seconds) is stored in the other memory area of the memory unit 19.

Further, the buffers 40 and 42 are not limited to being disposed in the memory unit 19. For example, buffers 40, 42 may also be buffers internal to computing circuit 18.

Fig. 7 is a view for explaining a procedure of generating and storing data after detecting an instantaneous voltage drop. Referring to Fig. 7, calculation circuit 18 stores the instantaneous value of the voltage obtained by sampling and A/D conversion during one period T of AC voltage 30 in the memory unit 19 as waveform data. The calculation circuit 18 further calculates the sum of the squares of these instantaneous values and stores the sum of squares in the memory unit 19.

The calculation circuit 18 stores the waveform data of five cycles from the detection of the instantaneous voltage drop in the memory unit 19. In addition, from the detection of the instantaneous voltage drop until five cycles have elapsed, The waveform data and the square sum corresponding to the waveform data are stored in the memory unit 19. After the sixth period from the detection of the instantaneous voltage drop, the calculation circuit 18 calculates the sum of squares for each period based on the A/D value, and stores the square sum in the memory unit 19. For example, during a period from the detection of the instantaneous voltage drop to the lapse of one second, the calculation circuit 18 stores the sum of the squares for each cycle in the memory unit 19.

As described above, the square sum is generated for each cycle within one second before the detection of the instantaneous voltage drop and the detection of the instantaneous voltage drop, and the sum of squares is stored in the memory unit 19. Further, after the instantaneous voltage drop is detected, the waveform data of five cycles of the AC voltage is stored in the memory unit 19. As a result, it is possible to store the data relating to the voltage immediately after the transient voltage drop and the voltage immediately after the instantaneous voltage drop, in the memory unit 19. Further, after detecting the instantaneous voltage drop, the sum of the squares for each cycle in one second is obtained, and only the waveform data of five cycles is acquired. That is, the period in which the waveform data is acquired is shorter than the period in which the square sum of each period is obtained. Thereby, the size of the data stored in the memory unit 19 can be controlled.

An instantaneous voltage drop may cause the power supply voltage of the power sensor 1 to temporarily drop. Thereby, the operation of writing data to the memory unit 19 is interrupted. Therefore, the writing time for writing data to the memory unit 19 is preferably a short time. According to the above configuration, by saving (reducing) the data size, the writing time for writing data to the memory unit 19 can be shortened. Thereby, the possibility of retaining the waveform data in the memory unit 19 can be improved.

Further, the average value (for every ten cycles) of the sum of the squares within ten seconds before the instantaneous voltage drop occurs is stored in the memory unit 19. Thereby, it is possible to grasp the outline transition of the voltage before the instantaneous voltage drop occurs.

Further, in the above-described embodiment, as one embodiment of the voltage monitoring device of the present invention, a power sensor is shown. However, as long as it is a device having the voltage monitoring function described in the above embodiment, the configuration of the device and other functions are not particularly limited.

Moreover, in the above-described embodiment, an example in which electric power is supplied to the module around the measurement unit 10 is shown as an example of the energy saving mode. For example, in the power saving mode, the operating clock frequency of the calculation circuit 18 (for example, the CPU) may be lowered in addition to or in place of the above control.

Further, in the above-described embodiment, as a method of calculating the data related to the effective value, it is necessary to calculate the sum of squares. However, it is also possible to calculate the effective value by converting the alternating voltage into a direct current voltage.

Further, in the above embodiment, in order to detect the instantaneous voltage drop, it is necessary to calculate the sum of squares in one cycle of calculating the alternating voltage. The time unit can also be, for example, one cycle or a complex cycle of the alternating voltage. However, in order to quickly detect an instantaneous voltage drop, it is preferably a short time unit.

It should be noted that the embodiments disclosed herein are illustrative in all aspects and are not restrictive. The scope of the present invention is not limited to the description of the above embodiments, but is defined by the scope of the patent claims, and includes the meaning equivalent to the scope of the patent claims and the contents of all the modifications within the scope.

1‧‧‧Power Sensor

1a, 1b‧‧‧ converter

2‧‧‧Electrical equipment in the area

2a‧‧‧Power lines

3, 8‧‧‧Auxiliary power supply

4‧‧‧Alarm device

5, 9‧‧‧ AC circuit

5a~5c‧‧‧Power line

6‧‧‧Load device

7‧‧‧Data processing device

10‧‧‧Measurement Department

11‧‧‧Voltage measurement department

11a‧‧‧voltage circuit

11b, 12b‧‧‧A/D conversion circuit

12‧‧‧Electrical Measurement Department

12a‧‧‧current/voltage conversion circuit

13‧‧‧Communication Control Department

14‧‧‧Connecting Department

15‧‧‧Signal path

15a‧‧‧Isolator (isolator)

16‧‧‧Power circuit

18‧‧‧Computation circuit

19‧‧‧ Memory Department

20‧‧‧ capacitor

21‧‧‧Semiconductor relay

30‧‧‧AC voltage

40, 42, B ₁ ~ B _x ‧ ‧ buffer

Fig. 1 is a view showing an embodiment of a voltage monitoring device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a main part of a power sensor according to an embodiment of the present invention.

3 is a view showing voltage monitoring processing executed by the electric quantity sensor 1 shown in FIGS. 1 and 2 flow chart.

4 is a diagram for explaining an example of a detection mode.

FIG. 5 is a diagram for explaining a method of generating monitoring data.

Fig. 6 is a view for explaining a procedure of generating and storing data before detecting a transient voltage drop.

Fig. 7 is a view for explaining a procedure of generating and storing data after detecting an instantaneous voltage drop.

1‧‧‧Power Sensor

1a, 1b‧‧‧ converter

4‧‧‧Alarm device

5‧‧‧AC circuit

5a~5c‧‧‧Power line

10‧‧‧Measurement Department

11‧‧‧Voltage measurement department

11a‧‧‧voltage circuit

11b, 12b‧‧‧A/D conversion circuit

12‧‧‧Electrical Measurement Department

12a‧‧‧current/voltage conversion circuit

13‧‧‧Communication Control Department

14‧‧‧Connecting Department

15‧‧‧Signal path

15a‧‧‧Isolator (isolator)

16‧‧‧Power circuit

18‧‧‧Computation circuit

19‧‧‧ Memory Department

20‧‧‧ capacitor

21‧‧‧Semiconductor relay

Claims (16)

A voltage monitoring device includes: a measuring unit that measures an AC voltage of a measurement portion, detects a transient voltage drop generated at the measurement portion, and a memory unit; and the memory unit generates the first history data and the second history data And storing the first history data and the second history data in the memory unit, wherein the first history data is at a first time interval in a first period until a detection time point of the voltage drop In the data relating to the transition of the AC voltage, the second history data refers to a transition of the AC voltage occurring at a second time interval after the detection time point of the instantaneous voltage drop; the second The time interval is shorter than the first time interval described above. The voltage monitoring device according to claim 1, wherein the measurement unit further generates waveform data of the AC voltage after detecting the instantaneous voltage drop, and stores the generated waveform data in the memory unit. The voltage monitoring device of claim 2, wherein the first history data includes: first data, which is data acquired for each first cycle of the alternating voltage during the first period, a second data, which is data acquired for each second period of the alternating current voltage in a second period until a time point when the instantaneous voltage drop is detected; The second history data includes third data, which is data acquired for each third period of the alternating voltage in a third period shorter than the first period; the first time interval is The first period corresponds to the second period, wherein the second period corresponds to the third period, and the second period is shorter than the first period. The voltage monitoring device according to claim 3, wherein the period in which the measurement unit acquires the waveform data is shorter than the third period. The voltage monitoring device of claim 3, wherein the first period corresponds to a complex period of the alternating voltage, and the second period and the third period correspond to one cycle of the alternating voltage The first data system indicates a sum of squares of voltage instantaneous values during a period of the complex period, and the second data and the third data system indicate instantaneous voltage values during a period of the one cycle of the alternating current voltage. The sum of the squares. The voltage monitoring device according to any one of claims 1 to 5, wherein the measurement unit generates a monitoring data by generating a sum of squares of voltage instantaneous values during a half cycle of the alternating current voltage And comparing the transition of the monitoring data with the set mode to detect the instantaneous voltage drop. The voltage monitoring device of claim 6, wherein the set mode is selected from a plurality of modes, wherein the voltage monitoring device further includes an alarm output unit, wherein the alarm output unit detects the instantaneous voltage drop. At the time of each of the plurality of alarms corresponding to the above-described plural mode, an alarm corresponding to the set mode is output. The voltage monitoring device of claim 1, wherein the memory unit non-volatilely memorizes the first history data and the second history data. A voltage monitoring method includes: a detecting step of measuring an alternating voltage of a measuring portion to detect a transient voltage drop generated in the measuring portion, and generating a first history data by the step of generating a first history data, the first The history data refers to the detection of the transient voltage drop occurring in the data of the transition of the AC voltage occurring at the first time interval in the first period up to the detection time point of the transient voltage drop. The step of data after the time point, the step of remembering, storing the generated data in the memory unit; the data generated after the detection time point includes the second history data, and the second history data is indicated by The second time interval is shorter than the first time interval in the transition of the alternating voltage that occurs at two time intervals. In the memory step, the memory unit stores the first history data and the second history data. The voltage monitoring method of claim 9, wherein the data generated after the detecting time point includes waveform data of the alternating voltage after detecting the instantaneous voltage drop, in the memory step The memory unit further memorizes the waveform data. The voltage monitoring method of claim 10, wherein the first history data includes: The first data is data acquired for each first period of the alternating voltage in the first period, and the second data is in a second period until a time point at which the instantaneous voltage drop is detected. And the data obtained for each second period of the alternating voltage; the second history data includes a third data, wherein the third data is for each of the alternating voltages in a third period shorter than the first period The data obtained in the third period; the first time interval corresponds to the first period, the second time interval corresponds to the third period, and the second period is shorter than the first period. The voltage monitoring method of claim 11, wherein the period in which the waveform data is generated is shorter than the third period. The voltage monitoring method of claim 11, wherein the first period corresponds to a complex period of the alternating voltage, and the second period and the third period correspond to one cycle of the alternating voltage The first data system indicates a sum of squares of voltage instantaneous values during a period of the complex period, and the second data and the third data system indicate instantaneous voltage values during a period of the one cycle of the alternating current voltage. The sum of the squares. The voltage monitoring method according to any one of claims 9 to 13, wherein in the step of detecting, generating a sum of squares of voltage instantaneous values during a half cycle of the alternating voltage The data is monitored, and the transition of the monitoring data is compared with the set mode to detect the instantaneous voltage drop. For example, the voltage monitoring method of claim 14 of the patent scope, wherein The mode set above is selected from the plurality of modes, and the voltage monitoring method further includes a step of outputting an alarm, and in the step of outputting the alarm, when detecting the instantaneous voltage drop, respectively generating the complex mode In the corresponding plural alarm, an alarm corresponding to the mode set above is output. The voltage monitoring method of claim 9, wherein the memory unit non-volatilely memorizes the first history data and the second history data.