JP2021035251A - AC system monitoring system - Google Patents

Abstract

To provide an AC system monitoring system that can surely detect voltage oscillation occurring in an AC system.SOLUTION: An AC system monitoring system is provided that includes a monitoring unit (21) monitoring voltage oscillation in an AC system (1), the monitoring unit comprises: a determination signal generation unit (22) that extracts an oscillation component of an AC voltage on the basis of an instantaneous value of the AC voltage measured in the AC system, and generates an abnormality determination signal (SJ) corresponding to the oscillation component of the extracted AC voltage; and an abnormality presence/absence determination unit (23) that determines the presence/absence of an abnormality in the oscillation of the AC voltage on the basis of the generated abnormality determination signal (SJ).SELECTED DRAWING: Figure 1

Description

The present invention relates to an AC system monitoring system.

In an AC system in which parallel devices are connected, transmission / distribution lines, transformers, shunt reactors, etc. are mainly composed of inductor (L) components, and power capacitors, harmonic filters, etc. are mainly composed of capacitor (C) components. Consists of. Since various devices such as distributed power sources and loads are connected to this type of AC system, an LC resonance circuit may be formed in the AC system. The LC resonant circuit formed in the AC system may cause vibration in the AC voltage and deteriorate the quality of the AC voltage.

As one of the techniques for preventing the deterioration of quality due to the vibration of the AC voltage in the AC system, it is known that the control parameter is lowered to suppress the vibration when it is determined that the vibration of the AC current or the reactive power continues (for example). , Patent Document 1).

Japanese Patent No. 36055516

However, it may be difficult to detect and suppress the vibration of the AC voltage generated in the AC system by the method of determining the vibration continuation of the AC current or the reactive power. For example, when voltage vibration occurs between the harmonic filter of the device and the other device due to the other device, the voltage vibration cannot be suppressed even if the control parameter of the device is changed. Therefore, in the method of suppressing the vibration based on the continuation of the vibration of the AC current or the reactive power, the vibration of the AC voltage may continue and expand.

In one aspect, it is an object of the present invention to provide an AC system monitoring system capable of reliably detecting voltage vibrations generated in an AC system.

The AC system monitoring system according to one aspect is an AC system monitoring system including a monitoring unit that monitors voltage vibration in the AC system, and the monitoring unit uses an instantaneous value of the AC voltage measured in the AC system. Based on this, the vibration component of the AC voltage is extracted, and the determination signal generation unit that generates the abnormality determination signal corresponding to the extracted vibration component of the AC voltage, and the AC voltage based on the generated abnormality determination signal. This is an AC system control system equipped with an abnormality presence / absence determination unit for determining the presence / absence of abnormality in the vibration of the AC system.

According to the above aspect, it is possible to provide an AC system monitoring system capable of reliably detecting voltage vibration generated in the AC system.

It is a figure explaining the configuration example of the AC system monitoring system which concerns on 1st Embodiment. It is a figure (the 1) explaining the structural example of the determination signal generation part. It is a figure (the 2) explaining the structural example of the determination signal generation part. It is a figure explaining the structural example of the abnormality presence / absence determination part. It is a figure explaining the operation of the monitoring unit which concerns on 1st Embodiment. It is a figure explaining the method of extracting the vibration component in the 5th configuration example of the determination signal generation part. It is a figure explaining the 1st application example of the monitoring part which concerns on 1st Embodiment. It is a figure explaining the example of the vibration component extracted by the determination signal generation unit and the determination threshold value in the abnormality presence / absence determination unit in the first application example. It is a figure explaining the 2nd application example of the monitoring part which concerns on 1st Embodiment. It is a figure explaining the configuration example of the monitoring part in the monitoring system of the AC system which concerns on 2nd Embodiment. It is a figure explaining the structural example of the determination signal generation unit and the abnormality presence / absence determination unit which concerns on 2nd Embodiment. It is a figure explaining an example of an evaluation period.

Hereinafter, embodiments of the AC system monitoring system will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram illustrating a configuration example of an AC system monitoring system according to the first embodiment. The AC system 1 illustrated in FIG. 1 includes a power generation facility 2 and a generator 3 for transmitting AC power to a transmission line 4. The transmission line 4 contains an inductor (L) component such as a reactor 5 and a resistor 6. Further, a load 7, a power factor improving capacitor 8, and the like are connected to the transmission line 4.

The power generation facility 2 includes a first distributed power source 11A and a second distributed power source 11B, which are parallel devices connected to the AC system 1. FIG. 1 shows a photovoltaic power generation system as an example of the first distributed power source 11A and the second distributed power source 11B. The first distributed power source 11A and the second distributed power source 11B include a solar panel 12, an inverter device 13, a harmonic filter 14 (reactor 15 and a capacitor 16), a transformer 17, and a switch 18, respectively. .. The first distributed power source 11A and the second distributed power source 11B each convert the DC power output from the solar panel 12 by the photoelectric effect into AC power by the inverter device 13. The converted AC power is output via the harmonic filter 14, the transformer 17, and the switch 18. The AC power output from the first distributed power source 11A and the second distributed power source 11B is transmitted to the outside of the power generation facility 2 (transmission line 4 of the AC system 1) via the transformer 19. The inverter device 13, the harmonic filter 14, the transformer 17, and the switch 18 in the first distributed power source 11A are incorporated in, for example, a single electric device (power conditioner). Similarly, the inverter device 13, the harmonic filter 14, the transformer 17, and the switch 13 in the second distributed power source 11B are incorporated in, for example, a single electric device.

Further, the AC system 1 according to the present embodiment includes a monitoring unit 21 as a monitoring system for monitoring the vibration of the AC voltage and a protection unit 25. In the AC system 1 illustrated in FIG. 1, a monitoring unit 21 and a protection unit 25 are provided in the power generation facility 2.

The monitoring unit 21 monitors the presence or absence of abnormal vibration of the AC voltage in the AC system. The monitoring unit 21 measures the instantaneous value of the AC voltage in the AC system, and monitors the presence or absence of an abnormality in the vibration of the AC voltage based on the instantaneous value of the AC voltage. The monitoring unit 21 illustrated in FIG. 1 is an AC voltage measured by a voltage measuring instrument 24 at a connection between a power generation facility 2 including a first distributed power source 11A and a second distributed power source 11B and a transmission line 4 of the AC system 1. The instantaneous value v of is acquired. When there is an abnormality in the vibration of the AC voltage, the monitoring unit 21 outputs a signal instructing the protection unit 25 to protect the AC system 1. When there is an abnormality in the vibration of the AC voltage, the protection unit 25 disconnects one or more of the distributed power sources in the power generation facility including the first distributed power source 11A and the second distributed power source 11B. The protection unit 25 illustrated in FIG. 1 turns off the switch 18 of any of the distributed power sources in the power generation facility 2 including the first distributed power source 11A and the second distributed power source 11B through the control bus 26 to turn off the distributed power source. Dissolve. The protection unit 25 may stop the parallel type equipment instead of disassembling the parallel type equipment such as the distributed power source.

The monitoring unit 21 includes a determination signal generation unit 22 and an abnormality presence / absence determination unit 23. The determination signal generation unit 22 generates an abnormality determination signal used for determining the presence or absence of an abnormality in vibration generated in the AC voltage based on the instantaneous value v of the AC voltage. The determination signal generation unit 22 according to the present embodiment is 0 or more, and generates an abnormality determination signal having a value corresponding to the magnitude of the vibration component of the AC voltage extracted based on the instantaneous value v of the AC voltage. To do. The abnormality determination unit 23 determines whether or not there is an abnormality in the vibration of the AC voltage based on the abnormality determination signal generated by the determination signal generation unit and a predetermined threshold value. Although not shown in FIG. 1, the determination signal generation unit 22 includes an information holding unit that holds various information used for generating an abnormality determination signal, and the abnormality presence / absence determination unit 23 is used for determining the presence / absence of an abnormality. Includes an information holding unit that holds various types of information.

FIG. 2 is a diagram (No. 1) for explaining a configuration example of the determination signal generation unit. FIG. 3 is a diagram (No. 2) for explaining a configuration example of the determination signal generation unit.

FIG. 2A shows an example of the determination signal generation unit 22 that extracts the vibration component of the AC voltage by the high-pass filter as the first configuration example of the determination signal generation unit 22. The determination signal generation unit 22 of the first configuration example includes a low-pass filter 31, a subtractor 32, a square calculation unit 33, a moving average calculation unit 34, and a square root calculation unit 35.

The low-pass filter 31 and the subtractor 32 function as a high-pass filter. The low-pass filter 31 removes a component having a frequency higher than the cutoff frequency included in the instantaneous value v of the AC voltage which is the input signal of the determination signal generation unit 22. Here, the cutoff frequency of the low-pass filter 31 is set to be equal to or higher than the rated frequency (for example, 50 Hz or 60 Hz) of the AC voltage in the AC system 1. The subtractor 32 subtracts the signal from which the high frequency component of the input signal has been removed by the low-pass filter 31 from the input signal. That is, the determination signal generation unit 22 of the first configuration example extracts a component having a frequency higher than the cutoff frequency of the low-pass filter 31 included in the instantaneous value v of the AC voltage as a vibration component of the AC voltage.

The square calculation unit 33, the moving average calculation unit 34, and the square root calculation unit 35 function as a signal generation unit that generates an abnormality determination signal based on the vibration component extracted from the AC voltage. The square calculation unit 33 calculates the squared value of each measurement time value in the vibration component of the AC voltage extracted by the low-pass filter 31 and the subtractor 32. The moving average calculation unit 34 calculates the moving average of the values at each measurement time calculated by the square calculation unit 33 with respect to the square value. The square root calculation unit 35 calculates the square root of the value at each measurement time in the moving average calculated by the moving average calculation unit 34. The determination signal generation unit 22 of the first configuration example outputs the value of the square root calculated by the square root calculation unit 35 to the abnormality presence / absence determination unit 23 as the abnormality determination signal SJ.

FIG. 2B shows an example of the determination signal generation unit 22 that extracts the vibration component of the AC voltage by the bandpass filter as the second configuration example of the determination signal generation unit 22. The determination signal generation unit 22 of the second configuration example includes a bandpass filter 36, a subtractor 32, a square calculation unit 33, a moving average calculation unit 34, and a square root calculation unit 35.

The bandpass filter 36 and the subtractor 32 function as a bandpass filter that extracts vibration components in a frequency band different from the rated frequency of the AC system from the instantaneous value v of the AC voltage. The bandpass filter 36 in the determination signal generation unit 22 of the second configuration example has the rated frequency of the AC voltage, which is the input signal of the determination signal generation unit 22, as the center frequency, and has a predetermined frequency band including the center frequency. Extract (pass) only the components. The subtractor 32 subtracts the signal component extracted by the bandpass filter 36 from the input signal. That is, the determination signal generation unit 22 of the second configuration example extracts a signal included in the instantaneous value v of the AC voltage from which the component of the predetermined frequency band including the rated frequency is removed as the vibration component of the AC voltage. ..

The square calculation unit 33, the moving average calculation unit 34, and the square root calculation unit 35 function as a signal generation unit that generates an abnormality determination signal SJ based on the vibration component extracted from the AC voltage, as in the first configuration example. ..

FIG. 2C shows another example of the determination signal generation unit 22 that extracts the vibration component of the AC voltage by the bandpass filter as a third configuration example of the determination signal generation unit 22. The determination signal generation unit 22 of the third configuration example includes a bandpass filter 37, a square calculation unit 33, a moving average calculation unit 34, and a square root calculation unit 35.

The bandpass filter 37 functions as a bandpass filter that extracts vibration components in a frequency band different from the rated frequency of the AC system from the instantaneous value v of the AC voltage. The bandpass filter 37 in the determination signal generation unit 22 of the third configuration example has a predetermined frequency higher than the rated frequency of the AC voltage, which is the input signal of the determination signal generation unit 22, as the center frequency. Only the components of a predetermined frequency band including the frequency are extracted (passed). That is, the determination signal generation unit 22 of the third configuration example extracts a component of a predetermined frequency band, which is higher than the rated frequency, included in the instantaneous value v of the AC voltage as a vibration component of the AC voltage.

The square calculation unit 33, the moving average calculation unit 34, and the square root calculation unit 35 function as a signal generation unit that generates an abnormality determination signal SJ based on the vibration component extracted from the AC voltage, as in the first configuration example. ..

FIG. 3D shows yet another example of the determination signal generation unit 22 that extracts the vibration component of the AC voltage by the bandpass filter as the fourth configuration example of the determination signal generation unit 22. .. The determination signal generation unit 22 of the fourth configuration example includes a bandpass filter 36, square calculation units 33A and 33B, moving average calculation units 34A and 34B, square root calculation units 35A and 35B, and a subtractor 32. Including. The center frequency of the bandpass filter 36 in the fourth configuration example is the rated frequency of the AC voltage of the AC system 1.

The determination signal generation unit 22 of the fourth configuration example moves the square calculation units 33A and 33B for each of the input signal (instantaneous value v of the AC voltage) and the components of the input signal that have passed through the bandpass filter 36. After performing arithmetic processing by the average calculation units 34A and 34B and the square root calculation units 35A and 35B, the subtractor 32 generates an abnormality determination signal SJ and outputs the abnormality determination signal SJ to the abnormality presence / absence determination unit 23.

In FIG. 3 (e), as a fifth configuration example of the determination signal generation unit 22, determination to extract the vibration component of the AC voltage based on the difference between the instantaneous values v of the two AC voltages having different measured times. An example of the signal generation unit 22 is shown. The determination signal generation unit 22 of the fifth configuration example includes a past value output unit 38, a subtractor 32, a square calculation unit 33, a moving average calculation unit 34, and a square root calculation unit 35.

The past value output unit 38 includes, for example, a ring buffer that holds instantaneous values for n samples in the measurement calculation cycle, and is in the ring buffer at time t when the latest instantaneous value v is input to the determination signal generation unit 22. n After outputting the instantaneous value (past value) Z ⁻ⁿ before the sample, the past value Z ⁻ⁿ is overwritten with the instantaneous value v (t) at time t. ^{The subtractor 32 subtracts the past value Z −n} from the instantaneous value v (t) at time t.

The square calculation unit 33, the moving average calculation unit 34, and the square root calculation unit 35 function as a signal generation unit that generates an abnormality determination signal SJ based on the vibration component extracted from the AC voltage, as in the first configuration example. ..

The configuration of the determination signal generation unit 22 according to the present embodiment is not limited to the above-mentioned five types of configurations, and can be appropriately changed as long as it does not deviate from the gist of the present invention. For example, the configuration for generating the abnormality determination signal SJ based on the vibration component extracted from the instantaneous value of the AC voltage is limited to the combination of the square calculation unit 33, the moving average calculation unit 34, and the square root calculation unit 35 described above. However, it can be changed as appropriate. The determination signal generation unit 22 may be configured to calculate the absolute value of the extracted vibration component and generate the abnormality determination signal SJ based on the moving average of the absolute value, for example. Further, the determination signal generation unit 22 may have a configuration in which, for example, the moving average calculation unit 34 is replaced with a low-pass filter. Further, not limited to the configuration example described above, the configuration for generating the abnormality determination signal SJ based on the extracted vibration component in the determination signal generation unit 22 converts the positive / negative vibrating vibration component into a positive value. Any configuration may be included as long as it includes a process for performing the process and a process for smoothing the signal used for generating the abnormality determination signal SJ. By performing a signal smoothing process, an abnormality determination signal SJ capable of appropriately determining the presence or absence of an abnormality even when the time variation of the signal used for generating the abnormality determination signal SJ is large is obtained. Can be generated.

FIG. 4 is a diagram illustrating a configuration example of the abnormality presence / absence determination unit. In FIGS. 4A to 4C, there is an abnormality determination unit 23 in the case where the abnormality determination signal SJ (≧ 0) becomes larger as the vibration component extracted from the instantaneous value v of the AC voltage becomes larger. The configuration example of is shown.

FIG. 4A shows a first configuration example of the abnormality presence / absence determination unit 23. The abnormality presence / absence determination unit 23 of the first configuration example determines whether the vibration of the AC voltage is within the normal range or is abnormal depending on the magnitude relationship between the abnormality determination signal SJ (≧ 0) and the determination threshold value TH1. The determination unit 41 is included. The determination unit 41 determines that the vibration of the AC voltage is abnormal when SJ ≧ TH1. The determination unit 41 outputs to the protection unit 25 a determination result of whether the vibration of the AC voltage is within the normal range or abnormal. When the determination result indicates that it is abnormal, the protection unit 25 disconnects or stops a predetermined parallel type device (for example, the first parallel type device 11A or the second parallel type device 11B in FIG. 1). Etc. are carried out.

As described above, the abnormality determination unit 23 of the first configuration example receives AC when the abnormality determination signal SJ according to the magnitude of the vibration component extracted based on the instantaneous value v of the AC voltage becomes the determination threshold TH1 or more. Judge that there is an abnormality in the voltage vibration. Therefore, the abnormality presence / absence determination unit 23 of the first configuration example can detect the abnormality of the vibration generated in the AC voltage of the AC system at an early stage.

In FIG. 4B, as a second configuration example of the abnormality presence / absence determination unit 23, the abnormality presence / absence determination unit that determines whether the vibration of the AC voltage is within the normal range or is abnormal using the integrated output. An example of 23 is shown. The abnormality presence / absence determination unit 23 of the second configuration example includes a first determination unit 42, an integrator circuit 43, and a second determination unit 44. The first determination unit 44 determines whether or not the abnormality determination signal SJ (≧ 0) is equal to or higher than the determination threshold value TH1, outputs 1 when SJ ≧ TH1, and outputs 1 when SJ <TH1. Outputs -1 to. The integrator circuit 43 time-integrates the value output by the first determination unit 42 and outputs the value. The integrator circuit 43 in the second configuration example outputs a value indicating a period in which the 1 is continuous when the first determination unit 42 continuously outputs the 1 as an integral output SK. The second determination unit 44 determines whether the vibration of the AC voltage is within the normal range or abnormal depending on the magnitude relationship between the output of the integration circuit (integration output SK) and the determination time TH2. The second determination unit 44 determines that the vibration of the AC voltage is abnormal when SK ≧ TH2. The second determination unit 44 outputs the determination result of whether the vibration of the AC voltage is within the normal range or abnormal to the protection unit 25. When the determination result indicates that it is abnormal, the protection unit 25 performs a protection operation such as disconnecting or stopping a predetermined parallel type device.

As described above, the abnormality presence / absence determination unit 23 of the second configuration example has an abnormality in the vibration of the AC voltage when the period (integrated output SK) in which the abnormality determination signal SJ is the threshold value TH1 or more becomes the determination time TH2 or more. Is determined. Therefore, the abnormality presence / absence determination unit 23 of the second configuration example is erroneously regarded as an abnormality when SJ ≧ TH1 due to momentary voltage fluctuations that occur in normal operation such as load loading, tap switching, and system switching. It is possible to prevent the determination, and it is possible to more accurately determine the presence or absence of an abnormality.

In FIG. 4C, as a third configuration example of the abnormality presence / absence determination unit 23, an abnormality presence / absence determination unit that determines whether the vibration of the AC voltage is within the normal range or is abnormal using the integrated output. 23 another example is shown. The abnormality presence / absence determination unit 23 of the third configuration example includes the subtractor 45, the integrator circuit 43, and the determination unit 46. The subtractor 45 outputs a value obtained by subtracting the determination threshold value TH1 from the abnormality determination signal SJ (≧ 0). The integrator circuit 43 time-integrates the value output by the subtractor 45 and outputs it. The integrator circuit 43 in the third configuration example outputs a value indicating the time integration of the value when the subtractor 45 continuously outputs a value of 0 or more as an integral output SL. The determination unit 46 determines whether the vibration of the AC voltage is within the normal range or abnormal depending on the magnitude relationship between the output of the integration circuit 43 (integration output SL) and the determination reference TH3. The determination unit 46 determines that the vibration of the AC voltage is abnormal when SL ≧ TH3. The determination unit 46 outputs to the protection unit 25 a determination result of whether the vibration of the AC voltage is within the normal range or abnormal. When the determination result indicates that it is abnormal, the protection unit 25 performs a protection operation such as disconnecting or stopping a predetermined parallel type device.

As described above, the abnormality presence / absence determination unit 23 of the third configuration example determines that the integrated value (integral output SL) of the difference between the two during the period when the abnormality determination signal SJ is the determination threshold value TH1 or more becomes the determination reference TH3 or more. Judge that there is an abnormality in the vibration of the AC voltage. Therefore, the abnormality presence / absence determination unit 23 of the third configuration example can prevent erroneous determination of an abnormality with respect to a momentary fluctuation that occurs in normal operation such as load loading, tap switching, and system switching. , The presence or absence of abnormality can be determined more accurately. Further, the abnormality presence / absence determination unit 23 of the third configuration example determines that the vibration is abnormal in a short period of time as the value obtained by subtracting the determination threshold value TH1 from the abnormality determination signal SJ is larger. Therefore, by applying the abnormality presence / absence determination unit 23 of the third configuration example, it is possible to detect an abnormality at an early stage when the vibration of the AC voltage is large.

In FIG. 4D, as a fourth configuration example of the abnormality presence / absence determination unit 23, the AC voltage is based on the relationship between the magnitude of the abnormality determination signal SJ and the duration of the abnormality determination signal SJ of the magnitude. An example of an abnormality presence / absence determination unit 23 for determining whether the vibration of the above is within a normal range or an abnormality is shown. The abnormality presence / absence determination unit 23 of the fourth configuration example includes a duration calculation unit 47, a determination time limit determination unit 48, and a determination unit 49.

The duration calculation unit 47 calculates and outputs the duration SH of the abnormality determination signal SJ within the range of the same magnitude or the same magnitude based on the magnitude of the input abnormality determination signal SJ. The determination time limit determination unit 48 includes determination information 50 indicating the relationship between the size of the predetermined abnormality determination signal SJ and the determination time TH4 which is the determination threshold value for whether or not the abnormality is present, and the input abnormality determination signal SJ. The determination time TH4 for the duration SH is determined based on the magnitude of. The relationship between the magnitude of the abnormality determination signal SJ in the determination information 50 and the determination time TH4 is, for example, as shown in FIG. 4 (d), that the determination time becomes shorter as the abnormality determination signal SJ increases. Correlate with. The determination unit 49 determines whether or not there is an abnormality in the vibration based on the duration SH output by the duration calculation unit 47 and the determination time TH4 output by the determination time determination unit 48. The determination unit 49 determines that the vibration of the AC voltage is abnormal when SH ≧ TH4. The determination unit 46 outputs to the protection unit 25 a determination result of whether the vibration of the AC voltage is within the normal range or abnormal. When the determination result indicates that it is abnormal, the protection unit 25 performs a protection operation such as disconnecting or stopping a predetermined parallel type device.

As described above, in the abnormality presence / absence determination unit 23 of the fourth configuration example, the duration SH of the magnitude when the abnormality determination signal SJ of a certain magnitude is input is set to the magnitude of the abnormality determination signal SJ. When the determination time limit TH4 or more determined based on the above is reached, it is determined that there is an abnormality in the vibration of the AC voltage. Therefore, like the abnormality presence / absence determination unit 23 of the second configuration example, the abnormality presence / absence determination unit 23 of the fourth configuration example can prevent erroneous determination of an abnormality with respect to the momentary fluctuation that occurs in normal operation. It is possible to more accurately determine the presence or absence of an abnormality. Further, in the abnormality presence / absence determination unit 23 of the fourth configuration example, the larger the abnormality determination signal SJ, the shorter the determination time TH4 until it is determined that there is an abnormality in the vibration. Therefore, the abnormality presence / absence determination unit 23 of the fourth configuration example can detect the abnormality at an early stage when the vibration of the AC voltage is large, as in the abnormality presence / absence determination unit 23 of the third configuration example. Further, the abnormality presence / absence determination unit 23 of the fourth configuration example determines the presence / absence of abnormality in the vibration of the AC voltage based on the magnitude of the abnormality determination signal SJ and the duration SH of the magnitude. Therefore, the processing load of the abnormality presence / absence determination unit 23 of the fourth configuration example is reduced as compared with the second configuration example and the third configuration example including the processing such as time integration by the integration circuit.

The configuration of the abnormality presence / absence determination unit 23 according to the present embodiment is not limited to the above-mentioned four types of configurations, and can be appropriately changed as long as it does not deviate from the gist of the present invention.

Further, there is no particular limitation on the combination of the configuration of the determination signal generation unit 22 and the configuration of the abnormality presence / absence determination unit 23 in the monitoring unit 21 according to the present embodiment. For example, the determination signal generation unit 22 having the above-mentioned five types of configurations can be combined with any of the above-mentioned four types of abnormality presence / absence determination units 23, respectively.

FIG. 5 is a diagram illustrating the operation of the operation of the monitoring unit according to the first embodiment.
As described above, the monitoring unit 21 according to the present embodiment acquires (measures) the instantaneous value v of the AC voltage in the AC system 1 and monitors the presence or absence of an abnormality in the vibration of the AC voltage. FIG. 5A shows an example of the instantaneous value v of the AC voltage acquired by the monitoring unit 21. The instantaneous value v of the AC voltage acquired by the monitoring unit 21 includes components of other frequency bands in the ideal AC voltage Vfr at the rated frequency represented by the sine wave, and depends on the components of the other frequency bands. Vibration occurs. If vibrations due to components in other frequency bands, particularly components higher than the rated frequency, continue and expand, the quality of the AC voltage of the AC system 1 deteriorates. However, in the method of determining the vibration continuation of the effective value such as AC current or reactive power as disclosed in Patent Document 1 described above, the instantaneous AC voltage is instantaneous as shown in the effective value Ve of FIG. 5 (a). The vibration continuation is determined in the state where the vibration of the value v is smoothed. Therefore, in the method of determining the vibration continuation based on the effective value, it is difficult to detect the vibration abnormality when the voltage vibration occurs between the harmonic filter of a certain parallel type device and another device. In some cases. Therefore, as shown in FIGS. 5 (b) and 5 (c), the monitoring unit 21 of the present embodiment extracts the vibration component Vosc based on the instantaneous value v of the AC voltage, and extracts the vibration component Vosc. The abnormality determination signal SJ is generated based on the above. The vibration component Vosc illustrated in FIG. 5B is an example of a vibration component extracted based on the instantaneous value v of the AC voltage. Further, the abnormality determination signal SJ illustrated in FIG. 5C is an example of a signal generated based on the vibration component extracted from the instantaneous value v of the AC voltage.

The abnormality determination signal SJ illustrated in FIG. 5 (c) is smaller than the determination threshold value TH1 until time t0, and becomes the determination threshold value TH1 or more after time t0. Here, assuming that the abnormality determination signal SJ is a signal generated by using the square calculation unit 33, the moving average calculation unit 34, and the square root calculation unit 35 as described above, the abnormality determination signal SJ is , 0 or more, and the larger the vibration component contained in the AC voltage, the larger the value. Therefore, the abnormality presence / absence determination unit 23 can determine that there is an abnormality in the vibration based on the movement determination signal SJ becoming the determination threshold value TH1 or more, as in the first configuration example described above.

Further, the abnormality presence / absence determination unit 23 has an abnormality in vibration when the period SK in which the abnormality determination signal SJ is the determination threshold value TH1 or more becomes the determination time limit TH2 or more, as in the second configuration example described above. May be determined. In the second configuration example of the abnormality presence / absence determination unit 23, for example, the period SK (the period from time t0 to time t1) that is equal to or higher than the determination threshold TH1 in the abnormality determination signal SJ illustrated in FIG. 5C is determined. When the time limit TH2 or more, it is determined that there is an abnormality in the vibration.

Further, the abnormality presence / absence determination unit 23 causes vibration when the integrated value SL of the value obtained by subtracting the determination threshold value TH1 from the abnormality determination signal SJ becomes the determination reference TH3 or more, as in the third configuration example described above. It may be determined that there is an abnormality. In the third configuration example of the abnormality presence / absence determination unit 23, for example, the integrated value SL of the SJ-TH1 in the period after the time t0 of the abnormality determination signal SJ illustrated in FIG. If so, it is determined that there is an abnormality in the vibration.

Further, although not shown, the abnormality presence / absence determination unit 23 determines the magnitude of the abnormality determination signal SJ and the duration of the abnormality determination signal SJ of the magnitude, as in the fourth configuration example described above. The presence or absence of an abnormality in vibration may be determined based on the information 50.

FIG. 6 is a diagram illustrating a method of extracting a vibration component in the fifth configuration example of the determination signal generation unit.

As described above with reference to FIG. 3 (e), the fifth configuration example of the determination signal generation unit 22 is the instantaneous value v (t) of the AC voltage at time t and the instantaneous value Z ^{− before n samples.} The vibration component of the AC voltage is extracted based on the difference from ^n. For example, when the instantaneous value v (t0) of the AC voltage at the time t0 in the graph of FIG. 6 is input to the determination signal generation unit 22, the past value output unit 38 is n sample periods before the time t0. ^{The past value Z −n} input at the time tp is output. Therefore, the subtractor 32 outputs a value (slope shown by a dotted line) obtained by subtracting ^{the past value Z −n} at time tp from the instantaneous value v (t0) at time t0. As shown in FIG. 6, when the instantaneous value v of the AC voltage contains a vibration component and the difference from the ideal AC voltage Vfr is large, the value output by the subtractor 32 and the ideal AC voltage. The difference from the value of the corresponding period in Vfr may be large. Further, in the case of the AC voltage, since the voltage of the AC system 1 is generally maintained at the rated voltage, the increase / decrease in the peak value is small. Therefore, the vibration component can be extracted without limiting the frequency band, or a plurality of frequency components can be extracted by using the difference from the ^{past value Zn} such as the determination signal generation unit 22 of the fifth configuration example. The vibration component can be extracted even when is mixed.

As described above, the monitoring unit 21 of the present embodiment extracts the vibration component of the AC voltage based on the instantaneous value v of the AC voltage, and generates the abnormality determination signal SJ based on the extracted vibration component. Therefore, it is possible to extract a vibration component that is difficult to detect with an effective value such as an alternating current or an ineffective power, and generate an abnormality determination signal SJ having a size corresponding to the vibration component.

Further, the protection unit 25 of the present embodiment performs a protection operation of disconnecting or stopping the parallel type equipment when it is determined that there is an abnormality in the vibration of the AC voltage. At this time, for example, did the protection unit 25 disconnect or stop one parallel type device considered to be one of the causes of the abnormal vibration, and the vibration abnormality was eliminated based on the output from the monitoring unit 21 thereafter? Judge whether or not. If the vibration abnormality is not resolved, the protection unit 25 changes the parallel type device to be disconnected or stopped until the vibration abnormality is resolved, and then the vibration abnormality is based on the output from the monitoring unit 21. Continues the process of determining whether or not is resolved. As described above, in the monitoring system of the AC system 1 according to the present embodiment, when abnormal vibration of the AC voltage is detected, the parallel type equipment considered to be one of the causes of the vibration is disconnected instead of suppressing the vibration. Or stop.

For example, if vibration occurs between the harmonic filter of one parallel device connected to the AC system and another device due to another device, even if the control parameters of the parallel device are changed. , Vibration may not be suppressed. In addition, it is very difficult to identify the device that caused the vibration in the AC system to which various devices are connected. Furthermore, although it may not have actively expanded the vibration, it is possible that a resonance point was formed due to the interconnection of the harmonic filters of the parallel type device, which contributed to the vibration. Therefore, as in the monitoring system of the present embodiment, the peripheral devices are simultaneously detected by detecting the abnormality of vibration based on the instantaneous value v of the AC voltage and performing the protection operation of disconnecting or stopping the parallel devices. By eliminating the possibility of disconnection and damage to peripheral equipment, the power quality of the AC system can be ensured.

The determination signal generation unit 22 in the monitoring unit 21 according to the present embodiment is, for example, each of the plurality of vibration components extracted from the instantaneous value v of the same AC voltage by a plurality of extraction methods having different extraction conditions for the vibration components. A plurality of abnormality determination signals may be generated based on the above. The abnormality presence / absence determination unit 23 in the monitoring unit 21 individually determines the presence / absence of a vibration abnormality based on each of the plurality of abnormality determination signals, and then finally determines the vibration abnormality based on the plurality of determination results. Judge the presence or absence of.

FIG. 7 is a diagram illustrating a first application example of the monitoring unit according to the first embodiment. FIG. 8 is a diagram illustrating an example of a vibration component extracted by the determination signal generation unit and a determination threshold value in the abnormality presence / absence determination unit in the first application example. FIG. 7 shows an application example relating to the configuration of the monitoring unit 21 in which the third configuration example of the determination signal generation unit 22 and the second configuration example of the abnormality presence / absence determination unit 23 are combined.

The determination signal generation unit 22 illustrated in FIG. 7 includes three sets of signal generation circuits corresponding to the determination signal generation unit described above as a third configuration example. The three sets of signal generation circuits extract the vibration component of the AC voltage based on the instantaneous value v of the same AC voltage, and generate an abnormality determination signal. Here, the three sets of signal generation circuits have different center frequencies of the bandpass filters 37 used for extracting the vibration components.

The first signal generation circuit generates an abnormality determination signal SJ1 based on the vibration component of a predetermined frequency band including the center frequency f1 extracted by the bandpass filter 37A having the center frequency f1. In the first signal generation circuit, the square calculation unit 33A, the moving average calculation unit 34A, and the square root calculation unit 35A generate the abnormality determination signal SJ1. The second signal generation circuit generates an abnormality determination signal SJ2 based on the vibration component of a predetermined frequency band including the center frequency f2 extracted by the bandpass filter 37B having the center frequency f2 (> f1). In the second signal generation circuit, the square calculation unit 33B, the moving average calculation unit 34B, and the square root calculation unit 35B generate the abnormality determination signal SJ2. The third signal generation circuit generates an abnormality determination signal SJ3 based on the vibration component of a predetermined frequency band including the center frequency f3 extracted by the bandpass filter 37C having the center frequency f3 (> f2). In the third signal generation circuit, the square calculation unit 33C, the moving average calculation unit 34C, and the square root calculation unit 35C generate the abnormality determination signal SJ3.

Here, in the three bandpass filters 37A, 37B, and 37C, as shown in FIG. 8, the magnitude relation of the center frequencies f1, f2, and f3 is f3> f2> f1 (> f0), and each band. The combination is such that the frequency bands passing through the pass filters 37A, 37B, and 37C do not overlap. The frequency f0 in FIG. 8 is the rated frequency of the AC system 1.

Further, the abnormality presence / absence determination unit 23 illustrated in FIG. 7 includes three sets of determination circuits corresponding to the above-mentioned abnormality presence / absence determination unit as a second configuration example, and further includes a final determination unit 51. Each of the three sets of determination circuits is one of the three abnormality determination signals SJ1, SJ2 and SJ3 generated by the determination signal generation unit 22, which are assigned so as not to overlap each other. Alternatively, it is determined whether or not there is an abnormality in the vibration of the AC voltage based on SJ3. The first determination circuit is based on the magnitude relationship between the integrated output SK1 for the first abnormality determination signal SJ1 output by the first determination unit 42A and the integration circuit 43A and the determination time TH2, and is based on the magnitude relationship of the vibration abnormality. The presence or absence is determined, and the determination result is output to the final determination unit 51. The second determination circuit is based on the magnitude relationship between the integrated output SK2 for the second abnormality determination signal SJ2 output by the first determination unit 42B and the integration circuit 43B and the determination time TH2, and is based on the magnitude relationship of the vibration abnormality. The presence or absence is determined, and the determination result is output to the final determination unit 51. The third determination circuit is based on the magnitude relationship between the integrated output SK3 for the third abnormality determination signal SJ3 output by the first determination unit 42C and the integration circuit 43C and the determination time TH2, and is based on the magnitude relationship of the vibration abnormality. The presence or absence is determined, and the determination result is output to the final determination unit 51. Here, the three first determination units 42A, 42B, and 42C have different determination thresholds TH11 and TH12 depending on the frequency bands of the corresponding vibration components of the input abnormality determination signals SJ1, SJ2, and SJ3, respectively. , TH13 is used.

The final determination unit 51 makes a final determination regarding the presence or absence of an abnormality in the vibration of the AC voltage based on the determination results of each of the three sets of determination circuits. The final determination unit 51 is, for example, an OR circuit that inputs the determination results of each of the three sets of determination circuits, and vibrations when one or more of the three determination results is a determination result that the vibration is abnormal. Outputs the judgment result that there is an abnormality in.

In this way, a plurality of abnormality determination signals are generated based on each of the plurality of vibration components having different frequency bands, and the final presence / absence of abnormality is determined based on the determination result of the presence / absence of abnormality for each of the abnormality determination signals. By making a determination, vibration can be reliably detected and a protective operation can be performed even if various vibration aspects occur.

The plurality of sets of signal generation circuits having different vibration component extraction conditions are not limited to the third configuration example of the determination signal generation unit 22 described above, but the first configuration example, the second configuration example, and the fourth configuration example. Any of the configuration example and the fifth configuration example, or other similar configurations may be used. For example, the plurality of sets of signal generation circuits may be a plurality of sets of signal generation circuits in which the values n of ^{the past values Z −n output by the past value output unit are different in the fifth configuration example.} Further, the plurality of sets of signal generation circuits having different extraction conditions of vibration components are a combination of a plurality of sets of signal generation circuits having different extraction methods of vibration components, for example, a signal generation circuit corresponding to the first configuration example and a fifth set of signal generation circuits. It may be a combination of a configuration example and a corresponding signal generation circuit. In addition, the plurality of sets of determination circuits for individually determining the presence or absence of an abnormality based on each of the plurality of abnormality determination signals are not limited to the second configuration example, but the first configuration example, the third configuration example, and the like. And any of the fourth configuration examples, or other similar configurations.

Further, when the AC system 1 to which the monitoring system according to the present embodiment is applied is a multi-phase AC such as a three-phase AC, the presence or absence of an abnormality in vibration is determined for each single-phase AC voltage, and the determination result is used. Based on this, the presence or absence of a final abnormality may be determined.

FIG. 9 is a diagram illustrating a second application example of the monitoring unit according to the first embodiment. FIG. 9 shows an application example relating to the configuration of the monitoring unit 21 in which the fifth configuration example of the determination signal generation unit 22 and the second configuration example of the abnormality presence / absence determination unit 23 are combined.

The determination signal generation unit 22 illustrated in FIG. 9 includes three sets of signal generation circuits corresponding to the determination signal generation unit described above as a fifth configuration example. ^{In the three sets of signal generation circuits, the values n of the past values Z −n} output by the past value output units 38A, 38B, and 38C are the same, and the instantaneous values of the input AC voltages are different. The instantaneous value v1 of the first line voltage Vab in the three-phase AC is input to the first signal generation circuit as the instantaneous value of the AC voltage. That is, the first signal generation circuit uses the subtractor 32A to perform the instantaneous value (past value) of the first line voltage Vab n samples before the instantaneous value v1 (t) of the first line voltage Vab at time t. ) The abnormality determination signal SJ1 is generated based on the vibration component extracted by subtracting ^{Z1 −n.} In the first signal generation circuit, the square calculation unit 33A, the moving average calculation unit 34A, and the square root calculation unit 35A generate the abnormality determination signal SJ1. The instantaneous value v2 of the second line voltage Vbc in the three-phase AC is input to the second signal generation circuit as the instantaneous value of the AC voltage. ^{That is, in the second signal generation circuit, the subtractor 32B causes the past value Z2 −n} of the second line voltage Vbc n samples before the instantaneous value v2 (t) of the second line voltage Vbc at time t. The abnormality determination signal SJ2 is generated based on the vibration component extracted by subtracting. In the second signal generation circuit, the square calculation unit 33B, the moving average calculation unit 34B, and the square root calculation unit 35B generate the abnormality determination signal SJ2. The instantaneous value v3 of the third line voltage Vca in the three-phase AC is input to the third signal generation circuit as the instantaneous value of the AC voltage. That is, the third signal generation circuit extracts the instantaneous value v3 (t) of the third line voltage Vca at time t by subtracting ^{the past value Z3 −n of the third line voltage Vca n samples before.} An abnormality determination signal SJ3 is generated based on the generated vibration component. In the third signal generation circuit, the square calculation unit 33C, the moving average calculation unit 34C, and the square root calculation unit 35C generate the abnormality determination signal SJ3.

Further, the abnormality presence / absence determination unit 23 illustrated in FIG. 9 includes three sets of determination circuits corresponding to the above-mentioned abnormality presence / absence determination unit as a second configuration example, and further includes a final determination unit 51. Each of the three sets of determination circuits has an AC voltage based on one of the three abnormality determination signals SJ1, SJ2 and SJ3 generated by the determination signal generation unit 22 and the abnormality determination signal SJ1, SJ2 or SJ3. Judge the presence or absence of abnormal vibration. The first determination circuit is based on the magnitude relationship between the integrated output SK1 for the first abnormality determination signal SJ1 output by the first determination unit 42A and the integration circuit 43A and the determination time TH2, and is based on the magnitude relationship of the vibration abnormality. The presence or absence is determined, and the determination result is output to the final determination unit 51. The second determination circuit is based on the magnitude relationship between the integrated output SK2 for the second abnormality determination signal SJ2 output by the first determination unit 42B and the integration circuit 43B and the determination time TH2, and is based on the magnitude relationship of the vibration abnormality. The presence or absence is determined, and the determination result is output to the final determination unit 51. The third determination circuit is based on the magnitude relationship between the integrated output SK3 for the third abnormality determination signal SJ3 output by the first determination unit 42C and the integration circuit 43C and the determination time TH2, and is based on the magnitude relationship of the vibration abnormality. The presence or absence is determined, and the determination result is output to the final determination unit 51. Here, the three first determination units 42A, 42B, and 42C use the same determination threshold value TH1 according to the input abnormality determination signals SJ1, SJ2, and SJ3, respectively.

The final determination unit 51 makes a final determination regarding the presence or absence of an abnormality in the vibration of the AC voltage based on the determination results of each of the three sets of determination circuits. The final determination unit 51 is, for example, an OR circuit that inputs the determination results of each of the three sets of determination circuits, and when one or more of the three determination results is a determination result that the vibration is abnormal, the vibration is generated. Outputs the judgment result that there is an abnormality.

In this way, three abnormality determination signals SJ1, SJ2, and SJ3 are generated based on each of the instantaneous values of the three single-phase AC voltages included in the three-phase AC, and the abnormality for each of the abnormality determination signals is generated. By finally determining the presence or absence of an abnormality based on the determination result of the presence or absence, it is possible to detect even when there is an abnormality in the vibration of the AC voltage of a certain phase. In three-phase alternating current, for example, vibration may occur in only one of the phases due to imbalance, but as in the second application example, the final judgment is performed after determining the presence or absence of vibration abnormality for each phase. This makes it possible to reliably detect an abnormality in vibration.

Even in the monitoring system applied to the AC system of three-phase AC, the plurality of sets of signal generation circuits provided in the determination signal generation unit 22 are not limited to the fifth configuration example, and the first to fourth configuration examples are described. It may be any of the configuration examples or other similar configurations. Further, the plurality of determination circuits provided in the abnormality presence / absence determination unit 23 are not limited to the second configuration example, but are any one of the first configuration example, the third configuration example, and the fourth configuration example, or other similarities. It may have the same configuration.

[Second Embodiment]
In this embodiment, another configuration example of the monitoring unit 21 in the AC system 1 illustrated in FIG. 1 will be described.

FIG. 10 is a diagram illustrating a configuration example of a monitoring unit in the AC system monitoring system according to the second embodiment. FIG. 11 is an explanatory diagram of a configuration example of a determination signal generation unit and an abnormality presence / absence determination unit according to the second embodiment.

The monitoring unit 21 illustrated in FIG. 10 includes a determination signal generation unit 22, an abnormality presence / absence determination unit 23, and an evaluation timing control unit 27.

The determination signal generation unit 22 has the same configuration as the fifth configuration example described above, and as shown in FIG. 11, the past value output unit 38, the subtractor 32, the square calculation unit 33, and the moving average calculation. A unit 34 and a square root calculation unit 35 are included. ^{In the subtractor 32, the determination signal generation unit 22 subtracts the instantaneous value (past value) Z −n} before n samples output by the past value output unit 38 from the instantaneous value v (t) of the AC voltage at time t. Then, the vibration component of the AC voltage is extracted. The determination signal generation unit 22 generates an abnormality determination signal SJ according to the extracted vibration component by the square calculation unit 33, the moving average calculation unit 34, and the square root calculation unit 35.

The abnormality presence / absence determination unit 23 has the same configuration as the second configuration example described above, and includes the first determination unit 42, the integrator circuit 43, and the second determination unit 44 as shown in FIG. .. The second determination unit 44 of the abnormality presence / absence determination unit 23 has an integral output SK output by the first determination unit 42 and the integration circuit 43 indicating a period during which the abnormality determination signal SJ is continuously equal to or higher than the threshold value TH. When the determination time limit TH2 or more is reached, it is determined that there is an abnormality in the vibration of the AC voltage.

The evaluation timing control unit 27 controls the timing at which the determination signal generation unit 22 generates the abnormality determination signal SJ and the abnormality presence / absence determination unit 23 executes the process of determining the presence / absence of an abnormality. The evaluation timing control unit 27 includes a zero cross detection unit 28 and a determination instruction unit 29. The zero cross detection unit 28 detects the time (zero cross point) at which the instantaneous value v of the AC voltage becomes 0. The determination instruction unit 29 determines whether or not there is an abnormality in the vibration of the AC voltage based on the instantaneous value of the AC voltage within a predetermined evaluation period set based on the detected zero cross point, and the determination signal generation unit 22 and the presence or absence of the abnormality. Let the determination unit 23 do this. The judgment instruction unit 29 operates the subtraction unit 32, the square calculation unit 33, the moving average calculation unit 34, and the square root calculation unit 35 of the judgment signal generation unit 22 only within a predetermined evaluation period, and the judgment signal generation unit 29. 22 is made to generate an abnormality determination signal SJ. Further, the determination instruction unit 29 receives the abnormality determination signal SJ generated by the determination signal generation unit 22 as an input, and the determination instruction unit 29 receives the second determination output SK output by the first determination unit 42 and the integration circuit 43. The determination unit 44 makes a determination.

^{In the fifth configuration example of the determination signal generation unit 22 described above, the past value Z −n} n samples before the instantaneous value v (t) of the AC voltage at time t is applied to the entire section of the instantaneous value v of the AC voltage. The value obtained by subtracting is used as a vibration component, and a process of generating an abnormality determination signal SJ is performed based on the vibration component. However, as described in the present embodiment, the determination signal generation unit 22 of the fifth configuration example determines the abnormality determination signal only during the period in which the approximation by the straight line passing through the zero cross point is established at the ideal AC voltage Vfr. SJ may be generated and the presence or absence of abnormality may be determined.

FIG. 12 is a diagram illustrating an example of an evaluation period.
The ideal AC voltage Vfr represented by a sine wave in the graph shown in FIG. 12 has a voltage of 0 at the time Tx, and the time Tx is the zero crossing point. The slope (differential coefficient) of the tangent line at the zero cross point of the ideal AC voltage Vfr is the slope shown by the thick dotted line, and the value of the AC voltage Vfr within the range of ± ΔT centered on the zero cross point Tx is the thick dotted line. It can be approximated to a straight line given by the slope of. Vibration different from the slope that is linearly approximated by extracting the vibration component by subtracting the ^{past value Z −n} from the instantaneous value v (t) only within the period during which linear approximation is possible at such an AC voltage Vfr. The components can be easily and reliably extracted.

If the predetermined evaluation period is set within the period in which the linear approximation is established with respect to the time change of the instantaneous value of the AC voltage, including the time when the instantaneous value v in the AC voltage without vibration becomes 0 (zero cross point). Good. That is, when a linear approximation is established for the instantaneous value of the ideal AC voltage Vfr within the period of ± ΔT centered on the zero cross point Tx, the maximum evaluation period is the period of ± ΔT centered on the zero cross point Tx. Become. The evaluation period may be a period within which the above linear approximation is established, and may be, for example, a period from the zero cross point Tx to + ΔT.

Although the embodiment of the AC system monitoring system according to the present invention has been described above, the AC system monitoring system according to the present invention is not limited to the above embodiment and can be appropriately changed without departing from the gist of the present invention. Is. For example, the monitoring unit 21 extracts the vibration component based on the instantaneous value v of the AC voltage measured at another position, not limited to the connection unit with the transmission line 4 in the power generation facility 2 as illustrated in FIG. The abnormality determination signal SJ may be generated. Further, for example, the parallel type equipment connected to the AC system 1 is not limited to the photovoltaic power generation system illustrated in FIG. 1, but is a power generation system using renewable energy such as wind power generation, or an SVC (Static Var Compensator). It may be a phase adjustment equipment such as STATCOM (STATic synchronous COMpensator), a power storage system including a power conditioner for power storage, a synchronous generator, or the like.

Further, the mounting form of the monitoring unit 21 and the protection unit 25, and the protection target (device that is disconnected or stopped when it is determined to be abnormal) are not limited to those illustrated in FIG. For example, the monitoring unit 21 and the protection unit 25 may be mounted inside the parallel type device (for example, the distributed power source 11A or the controller of the inverter device 13) and limited to the parallel type device in which the protection target is mounted.

1 AC system 2 Power generation equipment 3 Generator 4 Transmission line 5, 15 Reactor 6 Resistance 7 Load 8 Power factor improvement capacitor 11A, 11B Distributed power supply 12 Solar panel 13 Inverter device 14 Harmonic filter 16 Condenser 17, 19 Transformer 18 Switch 21 Monitoring unit 22 Judgment signal generation unit 23 Abnormality presence / absence judgment unit 24 Voltage measuring instrument 25 Protection unit 26 Control bus 27 Evaluation timing control unit 28 Zero cross detection unit 29 Judgment instruction unit 31 Low-pass filter 32, 32A, 32B, 32C subtractor 33, 33A, 33B, 33C Square calculation unit 34, 34A, 34B, 34C Mobile average calculation unit 35, 35A, 35B, 35C Square root calculation unit 36, 37, 37A, 37B, 37C Bandpass filter 38, 38A, 38B, 38C Past value Output units 41, 46, 49 Judgment units 42, 42A, 42B, 42C Judgment units 43, 43A, 43B, 43C Inverter circuits 44, 44A, 44B, 44C Judgment unit 45 Subtractor 47 Duration calculation unit 48 Judgment time determination unit 50 Judgment information 51 Final judgment unit

Claims (16)

An AC system monitoring system that includes a monitoring unit that monitors voltage vibrations in the AC system.
The monitoring unit
A determination signal generator that extracts the vibration component of the AC voltage based on the instantaneous value of the AC voltage measured in the AC system and generates an abnormality determination signal corresponding to the extracted vibration component of the AC voltage.
An AC system monitoring system including an abnormality presence / absence determination unit that determines the presence / absence of an abnormality in vibration of the AC voltage based on the generated abnormality determination signal. The AC system monitoring system according to claim 1, wherein the determination signal generation unit extracts a vibration component of the AC voltage based on a difference between two instantaneous values having different measured times. The monitoring unit further includes a detection unit that detects a zero crossing point at which the instantaneous value of the AC voltage becomes zero.
The determination signal generation unit measures the AC voltage within a period set based on the time when the zero cross point is detected and the section approximated by a straight line passing through the zero cross point in the AC voltage represented by the sine wave. The monitoring of the AC system according to claim 2, wherein the vibration component of the AC voltage is extracted based on the instantaneous value, and the abnormality determination signal is generated based on the extracted vibration component of the AC voltage. system. The AC system monitoring system according to claim 1, wherein the determination signal generation unit extracts the vibration component of the AC voltage by either a high-pass filter or a band-pass filter. The determination signal generation unit includes a processing unit that performs a process of converting the extracted vibration component of the AC voltage into a positive value and a process of smoothing the signal used for generating the abnormality determination signal. The AC system monitoring system according to claim 1, which is characterized. The processing unit of the determination signal generation unit calculates the first calculation unit that calculates the square of the vibration component extracted based on the instantaneous value of the AC voltage, and the calculated moving average of the square of the vibration component. The monitoring system for an AC system according to claim 5, further comprising a second calculation unit and a square root calculation unit for calculating the square root of the calculated moving average. The determination signal generation unit
A first processing unit that converts the instantaneous value of the AC voltage into a positive value and smoothes the converted positive value.
A second processing unit that extracts a predetermined frequency component included in the instantaneous value of the AC voltage, converts the frequency component into a positive value, and smoothes the converted positive value.
The AC system monitoring system according to claim 1, further comprising a subtraction unit that subtracts the output of the second processing unit from the output of the first processing unit to generate the abnormality determination signal. .. The first processing unit is configured to calculate the square of the instantaneous value of the AC voltage, calculate the moving average of the square of the instantaneous value, and calculate the square root of the moving average.
The second processing unit is configured to calculate the square of the frequency component extracted from the instantaneous value of the AC voltage, calculate the moving average of the square of the frequency component, and calculate the square root of the moving average. The AC system monitoring system according to claim 7, wherein the system is characterized by the above. The determination signal generation unit generates the abnormality determination signal, which is 0 or more and has a larger value as the vibration component of the AC voltage is larger.
The monitoring system for an AC system according to claim 1, wherein the abnormality determination unit determines that there is an abnormality in the vibration of the AC voltage when the abnormality determination signal is equal to or higher than a threshold value. The determination signal generation unit generates the abnormality determination signal, which is 0 or more and has a larger value as the vibration component of the AC voltage is larger.
The abnormality determination unit calculates a period during which the abnormality determination signal is equal to or greater than the first threshold value, and when the calculated period becomes equal to or greater than the second threshold value, there is an abnormality in the vibration of the AC voltage. The AC system monitoring system according to claim 1, further comprising determining that. The determination signal generation unit generates the abnormality determination signal, which is 0 or more and has a larger value as the vibration component of the AC voltage is larger.
The abnormality presence / absence determination unit calculates the time integration of the value obtained by subtracting the first threshold value from the abnormality determination signal, and when the calculated value of the time integration becomes equal to or greater than the second threshold value, the AC voltage. The AC system monitoring system according to claim 1, wherein it is determined that there is an abnormality in the vibration of the AC system. The determination signal generation unit generates the abnormality determination signal, which is 0 or more and has a larger value as the vibration component of the AC voltage is larger.
The abnormality determination unit determines the relationship between the predetermined magnitude of the abnormality determination signal and the determination time limit for the presence or absence of an abnormality in the vibration of the AC voltage, and the abnormality determination signal generated by the determination signal generation unit. The monitoring system for an AC system according to claim 1, wherein the presence or absence of an abnormality in vibration of the AC voltage is determined based on the magnitude and the duration of the abnormality determination signal of the magnitude. The AC system control system further includes a protection unit that protects parallel devices connected to the AC system based on the determination result of the abnormality presence / absence determination unit.
The AC system monitoring system according to claim 1, wherein the protection unit arranges the parallel devices. When the protection unit receives information indicating that the vibration abnormality continues from the abnormality presence / absence determination unit after disconnecting the parallel type device, the protection unit disconnects another parallel type device. 13. The AC system monitoring system according to claim 13. The determination signal generation unit extracts a plurality of vibration components having different extraction methods or extraction conditions based on the instantaneous value of the same AC voltage, and uses each of the extracted plurality of vibration components for a plurality of abnormality determinations. Generate a signal,
The abnormality presence / absence determination unit is characterized in that it determines the presence / absence of vibration abnormality based on each of the plurality of abnormality determination signals, and determines the presence / absence of vibration abnormality based on the determination results of the plurality of determinations. The AC system monitoring system according to claim 1. The determination signal generation unit extracts a plurality of vibration components based on each of the instantaneous values of a plurality of AC voltages having different phases, and outputs a plurality of abnormality determination signals based on each of the extracted plurality of vibration components. Generate and
The abnormality presence / absence determination unit is characterized in that it determines the presence / absence of vibration abnormality based on each of the plurality of abnormality determination signals, and determines the presence / absence of vibration abnormality based on the determination results of the plurality of determinations. The AC system monitoring system according to claim 1.

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