JP2017127192A - Uninterruptible power-supply system, and controller and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an uninterruptible power-supply system having a power peak-cut function.SOLUTION: An uninterruptible power-supply system includes a rectification section, a chargeable and dischargeable power storage section, and an inverter section. The rectification section converts AC power connected to an AC system into DC power. The power storage section is connected to a DC side of the rectification section. The inverter section converts DC power connected to the DC side of the rectification section into AC power. The uninterruptible power-supply system further includes an assist control section, a calculation section, and a stop section. The assist control section reduces the amount of power received from the AC system by controlling discharge of the power storage section. The calculation section calculates remaining dischargeable time of the power storage section. The stop section terminates assist control when the remaining dischargeable time reaches a predetermined lower limit.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a technique for controlling an uninterruptible power supply using a storage battery.

  An uninterruptible power supply (UPS) is used to protect important equipment such as a server computer from a power failure. In addition to offices and data centers, they are also being used in small office home offices (SOHO) and general homes.

JP 2004-229349 A

  In recent years, interest in energy management has increased in Japan, and attention has been focused on power peak cutting technology. However, a UPS having this type of function is not known. The function required for UPS is to be able to supply power stably, and it has been difficult to create a positive motivation to provide other functions. In the first place, since the remaining capacity of the large capacity storage battery used in the UPS could not be monitored, it was required to be always fully charged.

However, due to technological innovation, storage batteries that can be charged quickly with a large capacity and that can monitor the remaining capacity are being developed. If this type of storage battery is used, there is a possibility of providing an uninterruptible power supply system that has a peak cut function and contributes to energy management.
An object is to provide an uninterruptible power supply system having a peak cut function of power, a controller thereof, and a control method thereof.

  According to the embodiment, the uninterruptible power supply system includes a rectifying unit, a chargeable / dischargeable power storage unit, and an inverter unit. The rectifying unit converts AC power connected to the AC system into DC power. The power storage unit is connected to the DC side of the rectification unit. The inverter unit converts DC power connected to the DC side of the rectification unit into AC power. The uninterruptible power supply system further includes an assist control unit, a calculation unit, and a stop unit. The assist control unit controls the discharge of the power storage unit to reduce the amount of power received from the AC system. The calculation unit sequentially calculates the remaining dischargeable time of the power storage unit. The stop portion ends the assist control when the remaining dischargeable time reaches a predetermined lower limit value.

FIG. 1 is a functional block diagram illustrating an example of an uninterruptible power supply system according to the embodiment. FIG. 2 is a time chart for explaining the operation of the uninterruptible power supply system shown in FIG.

  FIG. 1 is a functional block diagram illustrating an example of an uninterruptible power supply system according to the embodiment. This system includes an uninterruptible power supply 2, a storage battery 6, and a controller 8. Among these, the storage battery 6 can utilize a lithium ion battery etc., for example.

  The uninterruptible power supply 2 is arranged between a load 7 provided in a customer facility (not shown) and the system 1.

  The uninterruptible power supply 2 includes a rectifier 3, a chopper 5, and an inverter 4. The rectifier 3 is connected to the system 1, rectifies the AC power received from the system 1, and supplies it to the inverter 4 and the chopper 5. The inverter 4 reversely converts the input DC power and supplies it to the load 7. The chopper 5 chops and supplies the DC power from the rectifier 3 to the storage battery 6 when the storage battery 6 is charged, and chops and supplies the DC power from the storage battery 6 to the inverter 4 when the storage battery 6 is discharged.

The controller 8 includes a setting unit 81, a stop unit 82, a calculation unit 83, a capacity monitor 84, a current sensor 85, and a scheduler 86.
The scheduler 86 can set start times of a plurality of operation modes, and changes the input power of the uninterruptible power supply 2 when a preset time is reached. The assist mode is a mode in which the amount of power received from the system 1 is reduced by discharging the storage battery 6 and assisting power supply to the load 7. In the assist mode, an input power Pin2 smaller than the input power Pin1 set in accordance with the load power is set. The normal operation mode is a mode in which the storage battery 6 is also charged, and the input power Pin1 set in accordance with the load power is canceled to make the input power the rated value of the rectifier 3.

The setting unit 81 presets a lower limit value of the remaining dischargeable time of the storage battery 6 in accordance with, for example, a user input operation. This lower limit value (set value) is transferred to the stop unit 82 and stored in an internal memory (not shown).
The capacity monitor 84 monitors the storage capacity of the storage battery 6. The current sensor 85 detects a current value flowing from the storage battery 6 to the load 7.
The calculation unit 83 calculates the remaining dischargeable time of the storage battery 6 based on the storage capacity of the storage battery 6 acquired by the capacity monitor 84 and the current value acquired by the current sensor 85. This calculated value is passed to the stop unit 82.

  The stop unit 82 compares the set value (from the setting unit 81) of the remaining dischargeable time with the calculated value (from the calculation unit 83). As a result of the comparison, if the set value ≧ the calculated value, the stop unit 82 ends the assist mode. That is, when the remaining dischargeable time reaches a predetermined lower limit after the assist mode is started by the scheduler 86, the stop unit 82 outputs an assist mode stop signal (c) to the uninterruptible power supply 2. Next, the operation of the above configuration will be described.

  FIG. 2 is a time chart for explaining the operation of the uninterruptible power supply system shown in FIG. In FIG. 2, it is assumed that the load 7 is operating at a constant load power (e), for example. The load power at this time is expressed as Pload. At this time, the uninterruptible power supply 2 is operated with the input power Pin1 set according to the load capacity (Pload).

  When the assist time t1 comes from this state, an assist mode command signal (b) is given to the uninterruptible power supply 2. As a result, the assist mode is started, the uninterruptible power supply 2 narrows the amount of power received from the system 1 to, for example, Pin2, the storage battery 6 operates in the discharge mode, and the backup power corresponding to (Pin1-Pin2) is applied to the load 7. Supply.

  In the assist mode, the controller 8 sequentially calculates the remaining dischargeable time of the storage battery 6. When the remaining dischargeable time reaches the lower limit (Clow shown in FIG. 2), the stop unit 82 outputs an assist mode stop signal (c) at that time (time t2), and cancels the assist mode command signal (b). (Pin2 value release command). As a result, the input power to the rectifier 3, that is, the amount of power received from the system 1 (d) returns to Pin1 again. While t1 is a preset time, t2 varies depending on the capacity of the storage battery 6, Pload, and the like.

  The assist mode is continued over a period (t1 to t2), and the input power of the uninterruptible power supply system can be reduced during this period.

  Next, when the time t3 shown in FIG. 2 arrives, the controller 8 outputs a normal operation signal to the uninterruptible power supply 2 and cancels the load power matching mode command signal (a). Then, Pin 1 is released (Pin 1 value release command), and charging of the storage battery 6 is started with the capacity of the normal rectifier 3.

  When the capacity of the storage battery 6 reaches 100% (time t4 shown in FIG. 2), the controller 8 gives a load power matching mode command signal to the uninterruptible power supply 2 and returns the input power to the rectifier 3 to Pin1. Control (Pin1 value command). As a result, the amount of power received becomes Pin 1 again, and the operation according to the load power is started.

  At this time, by setting t1 according to the time zone when the power demand is peaked and setting t3 according to the time zone when the power demand is reduced, peak cutting of the power can be realized.

  As described above, in this embodiment, a fast-chargeable storage battery 6 (such as a lithium ion battery) is connected to the uninterruptible power supply 2, and the discharge timing and the charge timing of the storage battery 6 are controlled, so that The input power to the power failure power supply system 2, that is, the amount of power received from the system 1 can be reduced over a certain period. Thereby, it becomes possible to suppress the peak power of the entire customer facility by assisting with the backup power from the storage battery 6 during the time when the power of the entire customer facility is at a peak.

  Moreover, the storage battery 6 which can be charged rapidly, such as a lithium ion battery, can be combined with the uninterruptible power supply 2 to construct a system that maximizes the capacity of the storage battery 6.

  From these things, it becomes possible to provide the uninterruptible power supply system provided with the peak cut function of electric power, its controller, and a control method.

  Although an embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... System | strain, 2 ... Uninterruptible power supply (UPS), 3 ... Rectifier, 4 ... Inverter, 5 ... Chopper, 6 ... Storage battery, 7 ... Load, 8 ... Controller, 81 ... Setting part, 82 ... Stop part, 83 ... Calculation unit, 84 ... capacity monitor, 85 ... current sensor, 86 ... scheduler.

Claims (12)

A rectifying unit that converts AC power connected to the AC system into DC power;
A chargeable / dischargeable power storage unit connected to the DC side of the rectifying unit;
An inverter unit for converting DC power connected to the DC side of the rectifying unit into AC power;
An assist control unit for controlling the discharge of the power storage unit to reduce the amount of power received from the AC system;
A calculation unit for sequentially calculating a remaining dischargeable time of the power storage unit;
An uninterruptible power supply system comprising: a stop unit that terminates assist control when the remaining dischargeable time reaches a predetermined lower limit. The calculator is
A capacity monitor for monitoring a power storage capacity of the power storage unit;
A sensor for detecting a current value flowing from the power storage unit,
The uninterruptible power supply system according to claim 1, wherein the remaining dischargeable time is calculated based on the storage capacity and the current value.   Furthermore, the uninterruptible power supply system of Claim 1 which comprises the setting part which sets the said lower limit according to a user's input operation.   The uninterruptible power supply system according to claim 1, wherein the power storage unit is a lithium ion battery. A rectifying unit that converts AC power connected to an AC system into DC power, a chargeable / dischargeable power storage unit connected to the DC side of the rectifying unit, and DC power connected to the DC side of the rectifying unit An uninterruptible power supply controller having an inverter unit for converting into electric power,
An assist control unit for controlling the discharge of the power storage unit to reduce the amount of power received from the AC system;
A calculation unit for sequentially calculating a remaining dischargeable time of the power storage unit;
A controller comprising: a stop unit that terminates assist control when the remaining dischargeable time reaches a predetermined lower limit value. The calculator is
A capacity monitor for monitoring a power storage capacity of the power storage unit;
A sensor for detecting a current value flowing from the power storage unit,
The controller according to claim 5, wherein the remaining dischargeable time is calculated based on the storage capacity and the current value.   Furthermore, the controller of Claim 5 which comprises the setting part which sets the said lower limit according to a user's input operation.   The controller according to claim 5, wherein the power storage unit is a lithium ion battery. A rectifying unit that converts AC power connected to an AC system into DC power, a chargeable / dischargeable power storage unit connected to the DC side of the rectifying unit, and DC power connected to the DC side of the rectifying unit A method for a controller to control an uninterruptible power supply having an inverter unit for converting to electric power,
The controller controls the discharge of the power storage unit to reduce the amount of power received from the AC system;
The controller sequentially calculates the remaining dischargeable time of the power storage unit;
A control method comprising: ending the assist control when the remaining dischargeable time reaches a predetermined lower limit value. Said calculating is
Monitoring the storage capacity of the storage unit;
Detecting a current value flowing from the power storage unit;
The control method according to claim 9, comprising calculating the remaining dischargeable time based on the storage capacity and the current value.   The control method according to claim 9, further comprising the controller setting the lower limit value input by a user.   The control method according to claim 9, wherein the power storage unit is a lithium ion battery.