JP7184717B2 - Uninterruptible power system - Google Patents

Description

The present disclosure relates to an uninterruptible power supply that switches a power supply circuit to a load when a commercial power supply fails.

Conventionally, there has been known an uninterruptible power supply that supplies electric power from a power storage device to a load when a commercial power supply fails (Patent Document 1).

JP-A-7-170677

In this regard, a configuration is shown in which the storage current to the storage device can be adjusted in accordance with load fluctuations. Control may become complicated when constantly monitoring and adjusting load fluctuations.

On the other hand, load fluctuations are predictable to some extent and can be adjusted based on the prediction.

The present disclosure has been made to solve the above problems, and provides an uninterruptible power supply capable of adjusting a storage current to a power storage device in a simple manner.

An uninterruptible power supply according to one aspect includes an AC/DC converter that converts an AC voltage to a DC voltage, a DC/AC converter that converts the DC voltage to an AC voltage and supplies the AC voltage to an AC load, and a DC/AC converter in parallel. A power storage device connected to store a DC voltage and supply power to an AC load, and a controller that controls the stored current to the power storage device in accordance with the AC load. The controller includes a storage unit that stores a plurality of power operation patterns for predicting an AC load that fluctuates according to time periods, and a current control unit that controls the storage current to the power storage device according to the power operation patterns stored in the storage unit. include.

Preferably, the current control unit adjusts the AC/DC converter to control the storage current to the power storage device.

Preferably, a chopper circuit is connected between the DC/AC converter and the power storage device to adjust the voltage level of the DC voltage. The current control unit adjusts the chopper circuit to control the storage current.

Preferably, the plurality of power operation patterns are set such that the maximum AC load differs according to the time of day, and one of the plurality of power operation patterns is assigned according to the day of the week.

Preferably, the current control unit sets the maximum value of the power storage current to the power storage device according to the power operation pattern.

According to one embodiment, the uninterruptible power supply can safely restore the power storage device.

It is a figure explaining composition of uninterruptible power supply 10 based on an embodiment. 4 is a diagram for explaining power operation patterns stored in a storage unit 42 based on the embodiment; FIG. 4 is a flow diagram illustrating control of a current control unit 40 based on the embodiment; FIG. It is a figure explaining the charging system of the conventional uninterruptible power supply. It is a figure explaining the charging method of the uninterruptible power supply 10 according to this embodiment.

This embodiment will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are given the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a diagram illustrating the configuration of an uninterruptible power supply 10 based on an embodiment.
As shown in FIG. 1 , uninterruptible power supply 10 is connected to AC input power supply 3 and load 20 .

The AC input power supply 3 is an AC power supply that supplies AC power to the uninterruptible power supply 10 . The input power supply is composed of, for example, a commercial AC power supply or a private power generator.

A three-phase three-wire (3φ3W) system is shown as an example of an input AC power supply. However, the type of input AC power supply is not limited to the three-phase three-wire system, and may be, for example, a three-phase four-wire power supply or a single-phase three-wire power supply.

The uninterruptible power supply 10 includes a converter 5 , a power storage device 30 , an inverter 7 , a chopper circuit 6 , and a controller 4 that controls the entire uninterruptible power supply 10 .

Converter 5 and inverter 7 are connected in series between AC input power supply 3 and load 20 .

Power storage device 30 is connected in parallel with inverter 7 to converter 5 via chopper circuit 6 .

Converter 5 converts an AC voltage supplied from AC input power supply 3 into a DC voltage. Inverter 7 converts the DC voltage converted by converter 5 into an AC voltage.

Chopper circuit 6 converts the voltage level of the DC voltage and supplies it to power storage device 30 .
Converter 5 , chopper circuit 6 and inverter 7 are each controlled by controller 4 .

Power storage device 30 includes a switch 32 and a secondary battery 34 .
Power storage device 30 is a device for supplying DC voltage to inverter 7 when AC input power supply 3 cannot supply AC voltage (for example, during a power failure). Note that the switch 32 is conducting, and the secondary battery 34 is being charged from the converter 5 .

When AC power is normally supplied from the AC input power supply 3 , the DC voltage generated by the converter 5 is stored in the power storage device 30 , converted to AC voltage by the inverter 7 , and supplied to the load 20 . On the other hand, during a power outage in which the supply of AC voltage from AC input power supply 3 is stopped, operation of converter 5 is stopped, and the DC voltage stored in power storage device 30 is converted into AC voltage by inverter 7 and supplied to load 20 . be. Therefore, according to the uninterruptible power supply, the operation of the load 20 can be continued using the electric power stored in the power storage device 30 even during a power failure.

The controller 4 is a control device for controlling the converter 5, the chopper circuit 6, the power storage device 30, and the inverter 7 in order to generate an AC voltage to be supplied to the load 20 during normal operation and power failure. It is mainly composed of a microcomputer including a CPU (Central Processing Unit) and a storage unit such as ROM (Read Only Memory) and RAM (Random Access Memory). Controller 4 controls converter 5 , chopper circuit 6 , power storage device 30 , inverter 7 and the like by causing CPU to read a program stored in ROM or the like in advance into RAM and execute the program.

Note that at least a part of the controller 4 may be configured to execute predetermined numerical/logical operation processing by hardware such as an electronic circuit.

Controller 4 includes a storage unit 42 and a current control unit 40 for controlling storage current for charging secondary battery 34 of storage device 30 .

FIG. 2 is a diagram illustrating power operation patterns stored in the storage unit 42 based on the embodiment.

As shown in FIG. 2, the storage unit 42 stores a plurality of power operation patterns.
In this example, power operation patterns A to C are provided.

Each power operation pattern is set with a predicted amount of AC load that fluctuates according to the time period.
As an example, the power operation pattern A is a normal power operation pattern, and as an example, the time slot of "0:00 to 9:00" is set to "30%". The time period of "9:00 to 19:00" is set to "70%". The time period of "19:00 to 24:00" is set to "30%".

The predicted amount here indicates a ratio to the maximum amount of electric power that can be supplied to the load 20 by the uninterruptible power supply 10 receiving an AC voltage input.

For example, if the uninterruptible power supply 10 can supply 200 kW, 70% will be 140 kW. In this example, a case where a ratio is set will be described, but the ratio is not particularly limited, and electric energy may be used, and other values may be used.

Power operation pattern B is a power operation pattern for late-night operation, and as an example, the time slot of "0:00 to 1:00" is set to "30%." The time period of "1:00 to 2:00" is set to "100%". The power operation pattern A is set to "30%" during the time period of "2:00 to 24:00".

Power operation pattern C is a power operation pattern for operation on holidays, and the time zone of "0:00 to 24:00" is set to "30%".

Also, the storage unit 42 shows a case where the power operation pattern is assigned to each day of the week.

Specifically, power operation patterns are assigned to Sunday through Saturday. For example, Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, and Saturday are assigned to power operation patterns "C", "A", "B", "A", "A", "B", and "B", respectively. is indicated.

FIG. 3 is a flowchart illustrating control of the current control section 40 based on the embodiment.
As shown in FIG. 3, the current control unit 40 acquires a power operation pattern (step S2). Specifically, the power operation pattern corresponding to the day of the week is acquired from among the plurality of power operation patterns stored in the storage unit 42 .

In this example, for example, the power operation pattern "A" is acquired.
Next, the current control unit 40 acquires the planned maximum load amount (step S4).

Specifically, the planned maximum load amount corresponding to the time period of the power operation pattern is obtained.

In this example, "70%" of the time period of "9:00 to 19:00" is acquired. For example, if the uninterruptible power supply 10 can supply 200 kW, 70% will be 140 kW.

Next, the current control unit 40 calculates the maximum limit charging amount (step S6). Specifically, the current control unit 40 calculates the maximum limit charge amount based on the planned maximum load amount and the power amount that can be supplied. For example, 200 kW−140 kW=60 kW is the amount of electric power that can be used to store power in the power storage device 30 .

The current control unit 40 calculates the maximum limit charging amount based on the electric energy.
Next, the current control unit 40 acquires load information (step S8).

Specifically, the current control unit 40 acquires load information by measuring the amount of current actually supplied from the uninterruptible power supply 10 to the load 20 .

Next, the current control unit 40 calculates the amount of chargeable current (step S10).
Specifically, the current control unit 40 calculates the chargeable current amount based on the actual load information that is measured. For example, when the actual load amount of the load 20 exceeds the planned maximum load amount, the chargeable current amount becomes small. On the other hand, when the actual load amount of the load 20 does not exceed the planned maximum load amount, the chargeable current amount increases.

Next, the current control unit 40 determines whether or not the chargeable current amount is within the maximum limit charging amount (step S12).

When the current control unit 40 determines that the chargeable current amount is within the maximum limit charge amount (YES in step S12), the current control unit 40 sets the current amount of the stored current to the chargeable current amount (step S14). Specifically, the current control unit 40 instructs the chopper circuit 6 to adjust the current amount of the stored current. For example, by adjusting the voltage level converted by the chopper circuit 6, it is possible to adjust the current amount of the stored current.

Then, the processing is terminated (END).
On the other hand, when determining that the chargeable current amount is not within the maximum limit charge amount (NO in step S12), the current control unit 40 sets the current amount of the storage current to the maximum limit charge amount (step S14). Specifically, the current control unit 40 instructs the chopper circuit 6 to adjust the current amount of the stored current. For example, by adjusting the voltage level converted by the chopper circuit 6, it is possible to adjust the current amount of the stored current.

Then, the processing is terminated (END).
When it is determined that the chargeable current amount is within the maximum limit charging amount, the current amount of the storage current is set to the chargeable current amount to supply power from the uninterruptible power supply 10 to the load 20 above the rating. It is possible to suppress

When it is determined that the chargeable current amount is not within the maximum limit charge amount, that is, the chargeable current amount is larger than the maximum limit charge amount, the current amount of the stored electric current is set to the maximum limit charge amount. By limiting the amount of charge to the maximum limit, it is possible to prevent the uninterruptible power supply 10 from supplying power to the load 20 in excess of the rated power even when the load fluctuates. It is also possible to suppress overcharging due to an increase in the storage current. With this method, it is possible to adjust the storage current to the power storage device 30 in a simple method according to the power operation pattern stored in the storage unit 42 .

FIG. 4 is a diagram illustrating a charging method of a conventional uninterruptible power supply.
As shown in FIG. 4 , when the amount of storage current for charging power storage device 30 is constant, it takes time to complete charging of power storage device 30 .

FIG. 5 is a diagram illustrating the charging method of the uninterruptible power supply 10 according to this embodiment.
As shown in FIG. 5, it is possible to significantly shorten the time until the charging of the power storage device 30 is completed by changing the amount of the storage current according to the load.

As a result, even if a power failure occurs during charging, it is possible to secure a long dischargeable time.

In this example, the chopper circuit 6 is instructed to adjust the amount of stored current, but the chopper circuit 6 is not adjusted. It is also possible to adjust the amount of stored electric current by adjusting the amount of electric power to be stored. Moreover, it is also possible to adopt a configuration in which the chopper circuit 6 is not provided in the configuration.

It should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

3 AC input power supply, 4 controller, 5 converter, 6 chopper circuit, 7 inverter, 10 uninterruptible power supply, 20 load, 40 current control section, 42 storage section.

Claims (5)

an AC-DC converter that converts AC voltage to DC voltage;
a DC/AC converter that converts the DC voltage into an AC voltage and supplies it to an AC load;
a power storage device connected in parallel with the DC/AC converter for storing the DC voltage and supplying power to the AC load;
a controller that controls a storage current to the power storage device according to the AC load;
The controller is
a storage unit storing a plurality of power operation patterns for predicting the AC load that fluctuates according to time zones;
a current control unit that controls the storage current to the power storage device according to the power operation pattern stored in the storage unit ;
The plurality of power operation patterns are set so that the maximum AC load differs according to the time period,
An uninterruptible power supply that is assigned one of the plurality of power operation patterns depending on the day of the week . 2. The uninterruptible power failure according to claim 1, wherein said current control unit calculates a maximum limit charge amount based on an assigned power operation pattern, adjusts said AC/DC converter, and controls the storage current to said power storage device. Power supply. The current control unit calculates a chargeable current amount based on the actual AC load, and adjusts the AC/DC converter based on a comparison between the calculated maximum limit charging amount and the calculated chargeable current amount. 3. The uninterruptible power supply according to claim 2, wherein the stored electric current to said electric storage device is controlled by controlling the storage current . A chopper circuit connected between the DC/AC converter and the power storage device for adjusting the voltage level of the DC voltage,
2. The uninterruptible power supply according to claim 1, wherein said current control unit calculates a maximum limit charging amount based on an assigned power operation pattern, adjusts said chopper circuit, and controls storage current. The current control unit calculates a chargeable current amount based on the actual AC load, and adjusts the chopper circuit based on a comparison between the calculated maximum limit charging amount and the calculated chargeable current amount. 5. The uninterruptible power supply according to claim 4, which controls the storage current .

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