JP2003061262A - Uninterruptible power supply and voltage failure detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the service life of a built-in battery well even if the quality of an input power supply is not high. SOLUTION: A determining means 21 determines if voltage failure exists in the input power supply based on whether or not a characteristic value showing the voltage waveform of the input power supply is within a prescribed range. A switching means 22 switches a power source from the input power supply to a battery 13 if it is determined that the determining member 21 determines that voltage failure exists in the input power supply, and a threshold changing means 23 changes a threshold for determining the prescribed range of the characteristic value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an uninterruptible power supply that switches an electric power source from an input power supply to a battery when an abnormal voltage of an input power supply is detected, and an abnormal voltage of the input power supply in the uninterruptible power supply. The present invention relates to a voltage abnormality detection method for doing so.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing an example of usage of an uninterruptible power supply. In the usage pattern shown in FIG. 6A, the uninterruptible power supply 101 is arranged between the commercial power supply 102, which is the input power supply in this case, and the load 103, and the power obtained from the commercial power supply 102 is stored in the built-in battery. When the voltage abnormality of the commercial power source 102 is detected, the power source is switched from the commercial power source 102 to the built-in battery,
The power supply to the load 103 is continued.

The usage pattern shown in FIG. 6B is an example in which an uninterruptible power supply 101 is installed in a building 201 such as an intelligent building or a hospital. In the case of this usage pattern, the building 201 is connected to the commercial power supply 102 and is also equipped with an emergency engine generator 104. A switching device 105 for switching the power supply source to the commercial power source 102 or the engine generator 104 is provided, and the lightning protection transformer 106 is provided on the load side of the switching device 105.
Are connected. And the uninterruptible power supply 101
It is arranged between the lightning protection transformer 106 and the load 103. In this case, the upstream side including the lightning protection transformer 106 serves as an input power source for the uninterruptible power supply device 101.

In this case, the uninterruptible power supply 101 switches the power source from the commercial power source 102 to the built-in battery during the period when the abnormal voltage of the commercial power source 102 is detected and the engine generator 104 is performing the starting process. When the power supply to the load 103 is continued and then the start of the engine generator 104 is completed, the switching device 105 connects the engine generator 104 to the load side, and the uninterruptible power supply device 101 supplies the power by the engine generator 104. Loaded power 103
Supply to.

As described above, the uninterruptible power supply 101 is directly connected to the commercial power supply 102 and the lightning protection transformer 106.
It may also be connected to the commercial power supply 102 via.

The uninterruptible power supply 101 is a lightning resistant transformer 10.
When connected to the commercial power supply 102 via 6, the distortion of the voltage waveform of the input power supply to the uninterruptible power supply 101 may depend on the impedance of the lightning protection transformer 106 and the load such as a rectifier connected to the lightning protection transformer 106. It can be high.

FIG. 7 is a diagram showing an example of the waveform of the voltage supplied to the uninterruptible power supply 101. FIG. 7A shows the waveform when the distortion rate is low, and FIG. ) Indicates a waveform when the distortion rate is high.

In the conventional uninterruptible power supply, when the characteristic value indicating the voltage waveform of the input power supply is out of a predetermined range, it is determined that the input power supply has a voltage abnormality. When the waveform distortion rate is high, voltage abnormalities are frequently detected, and the power source is frequently switched between the input power source and the built-in battery.

[0009]

As described above, when the conventional uninterruptible power supply is used, the distortion of the voltage waveform is high and the power source is frequently switched depending on the quality of the input power supply. However, there is a problem that the life of the built-in battery is shortened.

The present invention has been made in view of the above problems, and has an uninterruptible power supply and a voltage which can maintain a good life of the built-in battery even when the quality of the input power supply is not good. The purpose is to obtain an abnormality detection method.

[0011]

In order to solve the above problems, the uninterruptible power supply of the present invention is based on whether or not the characteristic value indicating the voltage waveform of the input power supply is within a predetermined range.
A determination unit that determines whether or not a voltage abnormality has occurred in the input power source, and a switching unit that switches the power source from the input power source to the battery when the determination unit determines that a voltage abnormality has occurred in the input power source. And threshold changing means for changing the threshold for determining the predetermined range of the characteristic value.

By using this uninterruptible power supply, even if the quality of the input power source is not good, the power source can be appropriately switched to the built-in battery and the life of the built-in battery can be kept good.

Further, in addition to the uninterruptible power supply device of the above invention, the uninterruptible power supply device of the present invention comprises an operation unit operated by a user or a worker, and the threshold value changing means responds to an operation on the operation unit. The threshold for determining the predetermined range of the characteristic value is changed.

When this uninterruptible power supply is used, even if the quality of the input power source differs depending on the region, the threshold value is appropriately adjusted, and the power source is switched to the built-in battery appropriately to improve the life of the built-in battery. Can be kept.

Further, in addition to the uninterruptible power supply device of the above invention, the uninterruptible power supply device of the present invention is characterized in that the threshold value changing means determines the characteristic value based on the frequency at which the judging means judges that the voltage abnormality has occurred. The threshold for determining the predetermined range of is changed.

When this uninterruptible power supply is used, the threshold value is appropriately set even when the quality of the input power source differs depending on the region, the power source is appropriately switched to the built-in battery, and the life of the built-in battery is kept good. be able to.

Further, in addition to the uninterruptible power supply device of the present invention, the uninterruptible power supply device of the present invention is characterized in that when the characteristic value becomes larger than the upper limit threshold value of the predetermined range, The threshold value is changed, and when the characteristic value becomes smaller than the lower limit threshold value of the predetermined range, the lower limit threshold value is changed.

When this uninterruptible power supply is used, the threshold value is set more appropriately, so that the life of the built-in battery can be kept better.

Further, in addition to the uninterruptible power supply device of the present invention, the uninterruptible power supply device of the present invention comprises an operation unit operated by a user or a worker, and the threshold value changing means is designated by an operation on the operation unit. The threshold for determining the predetermined range of the characteristic value is changed based on the history of the characteristic value in the period.

When this uninterruptible power supply is used, the threshold value is properly set even when the quality of the input power source differs depending on the region, the power source is switched to the built-in battery properly, and the life of the built-in battery is improved. Can be kept.

Further, in addition to the uninterruptible power supply device of the present invention, the uninterruptible power supply device of the present invention has a zero cross cycle, a slope of the voltage waveform, a peak value, an effective value, and a peak value as characteristic values indicating the voltage waveform of the input power supply. At least one of the rate and the waveform rate is used.

By using this uninterruptible power supply, the voltage waveform of the input power supply can be appropriately measured, and the power source can be appropriately switched to the built-in battery.

The voltage abnormality detecting method of the present invention is based on the step of changing a threshold value for determining a predetermined range of the characteristic value indicating the voltage waveform of the power supply, and whether or not the characteristic value is within the predetermined range. And a step of determining whether or not a voltage abnormality has occurred in the power supply.

By using this voltage abnormality detection method, even when the quality of the input power supply is not good, the switching of the power source to the built-in battery is made appropriate, and the life of the built-in battery of the uninterruptible power supply is improved. Can be kept.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 is a block diagram showing a configuration of an uninterruptible power supply according to Embodiment 1 of the present invention. In FIG. 1, the power device unit 1 has a rectifier 11, an inverter 12, and a battery 13, and is a part related to the supply of electric power to the load 103 shown in FIG. 6. Note that the power device unit 1 may have a different configuration.

The control circuit 2 is a circuit that monitors the power source voltage of the input power source, controls the power unit 1 as necessary, and switches the power source between the input power source and the battery 13.

FIG. 2 is a block diagram showing the configuration of the control circuit 2 in FIG. In FIG. 2, the determination means 21
Is a part that determines whether or not a voltage abnormality has occurred in the input power supply based on whether or not the characteristic value indicating the voltage waveform of the input power supply is within a predetermined range. Also, the switching means 22
Is a part that performs control to switch the power source from the input power source to the battery 13 when the determination means 21 determines that a voltage abnormality has occurred in the input power source. Further, the threshold changing unit 23 is a unit that changes the threshold that determines a predetermined range of the characteristic value indicating the voltage waveform of the input power supply.

Returning to FIG. 1, the storage unit 3 is a storage circuit such as a non-volatile ROM or RAM that stores a threshold value that determines a predetermined range of the characteristic value indicating the voltage waveform of the input power supply.

The operation unit 4 is a device such as a switch, a key, an adjustment dial operated by a user or a worker.

The control circuit 2 may be a CPU, a control program describing the operation of the control circuit 2 may be stored in the storage unit 3, and the control circuit 2 may perform processing according to the control program.

Next, the operation of the above device will be described.

In the uninterruptible power supply according to the first embodiment, when a predetermined operation is performed on the operation section 4 before or during operation, the threshold changing means 23 of the control circuit 2 responds to the operation. Then, the threshold value for determining the predetermined range of the characteristic value indicating the voltage waveform of the input power supply is changed.

However, the range in which the threshold can be changed is limited to the range in which the uninterruptible power supply operates normally. That is, for example, the threshold value is limited in advance so that the threshold value cannot be changed to a value that obviously affects the load 103 or increases the delay in switching the power source to the battery 13.

At this time, for example, the threshold value changing means 23 selects any one of a plurality of threshold values stored in the storage unit 3 in advance according to the operation. Alternatively, the threshold value changing means 23 may change the threshold value by an amount or a ratio according to the operation.

In this way, the threshold value for the characteristic value indicating the voltage waveform of the input power supply is changed / set as necessary. As an initial value, this threshold is set to a typical value such that the uninterruptible power supply operates normally.

In the normal state, the control circuit 2
Controls the power unit 1 to store the power obtained from the input power source in the battery 13 or to directly load the load 103.
To supply to.

In this state, the control circuit 2 monitors the voltage waveform of the input voltage. At this time, the determination unit 21 in the control circuit 2 reads the upper limit threshold value and the lower limit threshold value that determine the predetermined range of the characteristic value indicating the voltage waveform of the input power supply from the storage unit 3 and measures from the input power supply. Based on whether or not the characteristic value is within the predetermined range, it is determined whether or not a voltage abnormality has occurred in the input power supply. Further, the switching unit 22 in the control circuit 2 switches the power source from the input power source to the battery 13 when the determining unit 21 determines that the voltage abnormality occurs in the input power source,
The power supply to the load 103 by the power unit 1 is continued.

When the voltage abnormality is eliminated, the control circuit 2 switches the power source from the battery 13 to the input power source.

Next, the details of the operation when a voltage abnormality is detected will be described.

As an example, in the first embodiment, the cycle of the zero crossing point, the slope of the waveform, and the peak value are used as the characteristic values indicating the voltage waveform of the input power supply.
FIG. 3 is a diagram showing the zero-cross points of the voltage waveform of the input voltage, and FIG. 4 is a diagram showing the slope and peak value of the voltage waveform of the input voltage.

The control circuit 2 monitors the voltage value of the input power source, detects a time point when the voltage value crosses zero as a zero cross point Tz as shown in FIG. 3, and measures a cycle at which the zero cross point appears. .

Further, the control circuit 2 monitors the voltage value of the input power source and, for example, as shown in FIG. 4, the phase of the voltage waveform is 0.
In the range of ˜π / 3 and 2π / 3 to π, the slope of the waveform is measured. The slope of the waveform is calculated as a ratio between the phase difference between a certain phase θ2 and the phase θ1 and the difference between the voltage value V2 at the phase θ2 and the voltage value V1 at the phase θ1.
The inclination is measured once or plural times in each range of 0 to π / 3 and 2π / 3 to π.

Further, when the phase of the voltage waveform is in the range of π / 3 to 2π / 3, for example, as shown in FIG. 4, the control circuit 2 sets the maximum value of the voltage value in that range to the peak value Vp.
To detect as.

Although only the half cycle of the voltage waveform has been described here, the inclination and the peak value of the voltage waveform may be similarly measured in the remaining half cycle.

The control circuit 2 determines whether the characteristic value thus measured is within a predetermined range, for example.
The predetermined range is defined as a section between the upper limit threshold and the lower limit threshold, and the upper limit threshold and the lower limit threshold are stored in the storage unit 3 in advance. In some cases, the predetermined range may be defined only by the upper limit threshold value or the lower limit threshold value.

Regarding the slope of the voltage waveform, 0 to π
The same threshold value may be used in the range of / 3, or different threshold values may be used for each phase of the voltage waveform.

Then, the control circuit 2 determines that a predetermined number of characteristic values among the characteristic values being measured are out of the predetermined range, or that a certain characteristic value is out of the predetermined range continuously for a predetermined number of times. If it becomes, it is determined that a voltage abnormality has occurred.

As described above, in the first embodiment, the voltage abnormality is detected based on the relationship between the threshold value appropriately changed according to the predetermined operation on the operation unit 4 and the characteristic value indicating the voltage waveform of the input power source. It has been determined whether it has occurred.

As described above, according to the first embodiment, the first effect is that the determining means 21 determines whether or not the characteristic value indicating the voltage waveform of the input power source is within a predetermined range. It is determined whether or not a voltage abnormality has occurred in the input power source, and when the switching means 22 determines that the voltage abnormality has occurred in the input power source by the determination means 21, the power source is changed from the input power source to the battery. At the same time as switching to 13, the threshold changing means 23 changes the threshold for determining the predetermined range of the characteristic value. As a result, even when the quality of the input power source is not good, it is possible to appropriately switch the power source to the built-in battery 13 and maintain the life of the built-in battery 13 good.

Further, according to the first embodiment, as a second effect, the operation unit 4 operated by the user or the worker.
The threshold value changing means 23 changes the threshold value for determining the predetermined range of the characteristic value according to the operation on the operation unit 4. As a result, even if the quality of the input power source differs depending on the region, by appropriately setting the above threshold value, the switching of the power source to the built-in battery 13 is appropriately performed and the built-in battery 1
The life of 3 can be kept good.

Embodiment 2. The uninterruptible power supply according to the second embodiment of the present invention includes the threshold changing means 23 of the control circuit 2.
However, the threshold value for determining the predetermined range of the characteristic value is automatically changed based on the frequency at which the determination unit 21 determines that the voltage abnormality has occurred.

The configuration of the uninterruptible power supply according to the second embodiment is such that the control circuit 2 in the uninterruptible power supply according to the first embodiment is modified so as to operate as follows. Are the same, and the description thereof will be omitted.

Next, the operation of the above device will be described.

In the uninterruptible power supply according to the second embodiment, when the control circuit 2 determines that the voltage abnormality has occurred,
The occurrence time and the characteristic value that is a factor of the voltage abnormality are stored in the storage unit 3, and when the voltage abnormality occurs a predetermined number of times or more in a predetermined period, the characteristic value that is the factor of the voltage abnormality Change the threshold of.

When the same characteristic value becomes a factor of a voltage abnormality more than a predetermined number of times in a predetermined period, the threshold value of the characteristic value that becomes the factor of the voltage abnormality may be changed. Good.

In this case, for example, the threshold changing means 23 of the control circuit 2 changes the upper limit threshold when the characteristic value is larger than the upper limit threshold of the predetermined range, and the characteristic value is the lower limit of the predetermined range. If it is smaller than the threshold value on the side, the threshold value on the lower limit side may be changed. Alternatively, the upper limit threshold and the lower limit threshold may be changed in conjunction with each other without changing the width of the predetermined range.

The rate or amount of change in the threshold value may be determined according to the characteristic value that is a factor of the voltage abnormality, or may be set in advance by the user or a worker.

Regarding other operations, the first embodiment
Since it is similar to the case of 1, the description thereof will be omitted.

As described above, according to the second embodiment, in addition to the first effect of the first embodiment, the threshold changing means 23
However, since the threshold value for determining the predetermined range of the characteristic value is changed based on the frequency at which the determination unit 21 determines that the voltage abnormality has occurred, the threshold value is determined even when the quality of the input power source varies depending on the region. Is set appropriately, the switching of the power source to the built-in battery 13 becomes appropriate, and the life of the built-in battery 13 can be kept good.

Further, according to the second embodiment, when the characteristic value becomes larger than the upper limit threshold value of the predetermined range, the threshold value changing means 23 changes the upper limit threshold value to change the characteristic value. When is smaller than the lower limit threshold value of the predetermined range, the lower limit threshold value is changed, so that the above threshold value is set more appropriately, and the life of the built-in battery can be kept better.

Embodiment 3. In the uninterruptible power supply according to the third embodiment of the present invention, the threshold value changing unit 23 determines the predetermined range of the characteristic value based on the history of the characteristic value in the period designated by the operation on the operation unit 4. The threshold value to be set is automatically changed.

The configuration of the uninterruptible power supply according to the third embodiment is such that the control circuit 2 in the uninterruptible power supply according to the first and second embodiments is modified so as to operate as follows. Since the same is true for the part of, the description thereof will be omitted.

Next, the operation of the above device will be described.

In the uninterruptible power supply according to the second embodiment, the control circuit 2 causes the storage unit 3 to store a history of characteristic values indicating voltage waveforms during a certain period when a user or a worker operates the operation unit 4. It accumulates and changes the threshold value for the characteristic value based on the history. For example, this period is preferably at least 100 cycles. In addition, it is preferable to store the history while avoiding a time period when the load of the commercial power supply rises transiently.

For example, the control circuit 2 starts the history accumulation when the user or the worker performs a predetermined operation on the operation unit 4, and then the user or the worker performs a predetermined operation on the operation unit 4. Then, the history accumulation is ended. Then, when there is no switching of the power source to the battery 13 during the history accumulation period and there is an abnormality in the load 103 or the like, the control circuit 2 considers the history of characteristic values during that period and The threshold value for the characteristic value is changed so that the predetermined range in which the characteristic value is allowed becomes narrow. That is, it is not preferable for the operation of the uninterruptible power supply that the power source is not switched even though the load 103 or the like has an abnormality. On the other hand, when the switching of the power source to the battery 13 occurs frequently during the history accumulation period and there is no abnormality in the load 103 or the like, the history of the characteristic value in that period is taken into consideration and The threshold value is changed so that the predetermined range in which the characteristic value is allowed is wide. In this case, the threshold for the characteristic value is too strict, and the power source is switched unnecessarily.Therefore, the characteristic value is allowed in order to suppress such unnecessary switching of the power source. The range is widened.

At this time, the control circuit 2 determines whether or not there is an abnormality in the load 103 or the like based on an operation by a user or a worker.

Since the other operations are the same as those in any of the first and second embodiments, the description thereof will be omitted.

As described above, according to the third embodiment, in addition to the effect of the first or second embodiment, the operation unit 4 operated by the user or the worker is provided, and the threshold changing unit 2 is provided.
3 changes the threshold value that determines the predetermined range of the characteristic value based on the history of the characteristic value in the period designated by the operation on the operation unit 4. By this, even if the quality of the input power source varies depending on the region, the above threshold is set appropriately
The switching of the power source to the built-in battery 13 becomes appropriate, and the life of the built-in battery 13 can be kept good.

Fourth Embodiment The uninterruptible power supply according to Embodiment 4 of the present invention can exchange history data of characteristic values indicating the voltage waveform of the input power source or threshold values for each characteristic value via a communication line or a recording medium. It is the one.

FIG. 5 is a block diagram showing the configuration of the uninterruptible power supply according to the first embodiment of the present invention. In FIG. 5, the communication circuit 31 transmits history data of the characteristic values measured in this uninterruptible power supply device or a threshold value for each characteristic value set based on the historical data, or is measured in another uninterruptible power supply device or the like. It is a circuit that receives the historical data of the characteristic value or a threshold value for each characteristic value set based on the historical data. The communication line that can be used by the communication circuit 31 may be, for example, a telephone line or a computer network line such as the Internet.

Further, the drive unit 32 writes history data of the characteristic values measured in the uninterruptible power supply device or a threshold value for each characteristic value set on the basis of the history data into a recording medium (not shown) or another uninterruptible power supply. This is a device for reading the historical data of the characteristic values measured in the device or the like or the threshold value for each characteristic value set based on the historical data from a recording medium (not shown). As the recording medium, a rewritable recording medium such as a flexible disk, a CD-RW, or an MO disk can be used. Also, when only reading the history data,
A non-rewritable recording medium such as a CD-ROM may be used.

The configuration of the uninterruptible power supply according to the fourth embodiment in FIG. 5 is such that the control circuit 2 in the uninterruptible power supply according to the first to third embodiments is modified to operate as follows. Since the other parts are the same, the description thereof will be omitted.

Next, the operation of the above device will be described.

In the fourth embodiment, the control circuit 2 controls the communication circuit 31 or the driving device 32, and the history data of the characteristic values measured in the uninterruptible power supply device through the communication line or the recording medium. Alternatively, the threshold value for each characteristic value set based on the read value is read from the storage unit 3 and supplied to a center (not shown) or another uninterruptible power supply device.

In the fourth embodiment, the control circuit 2
Controls the communication circuit 31 or the driving device 32, and the history data of the characteristic values measured in another uninterruptible power supply device or the like via the communication line or the recording medium, or for each characteristic value set based on the history data. The threshold value is stored in the storage unit 3, and the acquired history data is used to change the threshold value for each characteristic value, or the acquired threshold value is used to update the threshold value for each characteristic value in the apparatus.

Since the other operations are the same as those in any of the first to third embodiments, the description thereof will be omitted.

As described above, according to the fourth embodiment, in addition to the effect of any of the first to third embodiments, the historical data of the characteristic value indicating the voltage waveform of the input power source or the threshold value for each characteristic value is set. Since the data can be sent and received via a communication line or a recording medium, for example, the history data of the characteristic value or the threshold value for each characteristic value can be supplied by exchanging the data in an area where the power quality is similar. It is possible to set the appropriate threshold value for each uninterruptible power supply device easily. Further, it is possible to easily obtain the history data of the above characteristic values in each uninterruptible power supply and easily manage each uninterruptible power supply.

As the characteristic value indicating the voltage waveform of the input power source, an effective value, a crest factor, a form factor, etc. may be used in addition to those used in the first to fourth embodiments. By using these characteristic values, the voltage waveform of the input power supply can be appropriately measured, and the power source for the built-in battery 13 can be switched appropriately.

[0079]

According to the present invention, it is possible to obtain an uninterruptible power supply device and a voltage abnormality detecting method which can maintain a good life of the built-in battery even when the quality of the input power source is not good.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an uninterruptible power supply according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control circuit in FIG.

FIG. 3 is a diagram showing a zero-cross point of a voltage waveform of an input voltage.

FIG. 4 is a diagram showing a slope and a peak value of a voltage waveform of an input voltage.

FIG. 5 is a block diagram showing a configuration of the uninterruptible power supply according to the first embodiment of the present invention.

FIG. 6 is a block diagram showing an example of usage of the uninterruptible power supply.

FIG. 7 is a diagram showing an example of a waveform of a voltage supplied to the uninterruptible power supply.

[Explanation of symbols]

4 operation part 21 Judgment means 22 Switching means 23 Threshold changing means 101 uninterruptible power supply

Claims (7)

[Claims] 1. An uninterruptible power supply that switches a power source from an input power supply to a battery when an abnormal voltage of the input power supply is detected, based on whether or not a characteristic value indicating a voltage waveform of the input power supply is within a predetermined range. And a determining means for determining whether or not a voltage abnormality has occurred in the input power source, and when the determining means determines that a voltage abnormality has occurred in the input power source, the power source is set to the input power source. From the battery to the battery, and a threshold changing unit that changes a threshold for determining a predetermined range of the characteristic value. 2. An operation unit operated by a user or a worker, wherein the threshold value changing unit changes a threshold value for determining a predetermined range of the characteristic value according to an operation on the operation unit. The uninterruptible power supply according to claim 1, which is characterized in that. 3. The threshold value changing means changes the threshold value for determining a predetermined range of the characteristic value based on the frequency with which the voltage abnormality is judged by the judging means. The uninterruptible power supply according to claim 1. 4. The threshold value changing means changes the upper limit threshold value when the characteristic value is larger than the upper limit threshold value of the predetermined range, and the characteristic value is the lower limit value of the predetermined range. The uninterruptible power supply device according to claim 3, wherein the threshold value on the lower limit side is changed when the threshold value is smaller than the threshold value on the lower side. 5. An operating unit operated by a user or a worker, wherein the threshold value changing unit determines a predetermined value of the characteristic value based on a history of the characteristic value in a period designated by an operation on the operating unit. The uninterruptible power supply according to claim 1, wherein a threshold value for determining the range is changed. 6. The characteristic value indicating the voltage waveform of the input power source is at least one of a zero-cross cycle, a slope of the voltage waveform, a peak value, an effective value, a peak ratio, and a waveform ratio. 6. The uninterruptible power supply device according to claim 5. 7. A voltage abnormality detecting method for detecting an abnormality in a power supply voltage, the step of changing a threshold value for determining a predetermined range for a characteristic value indicating a voltage waveform of a power supply, and the characteristic value being within a predetermined range. And a step of determining whether or not a voltage abnormality has occurred in the power source based on whether or not there is a voltage abnormality detection method.