JP2011223731A - Uninterruptible power supply system and control method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an uninterruptible power supply system having high system efficiency and redundancy.SOLUTION: An uninterruptible power supply system 1 converts the DC power stored in a storage device into AC power and supplies the converted AC power to a load 6 in case that abnormality occurs in a system 4. In the uninterruptible power supply system, a standby type uninterruptible power supply unit 3 and an on-line type uninterruptible power supply unit 3 are connected to each other in series between the system 4 and the load 6.

Description

  The present invention relates to an uninterruptible power supply, and more particularly to an uninterruptible power supply system that combines a continuous inverter power supply type uninterruptible power supply and a continuous commercial power supply type uninterruptible power supply.

  An uninterruptible power supply (UPS) is widely used as a power supply that continues to supply power to a load even if an instantaneous power failure or a power failure occurs in an input power supply. As an uninterruptible power supply device, a constant inverter power supply method and a constant commercial power supply method are generally known. Hereinafter, an outline of the uninterruptible power supply apparatus of the constant inverter power supply method and the constant commercial power supply method will be described.

(1) Constant inverter power supply method FIG. 7 shows an example of a circuit configuration diagram of the uninterruptible power supply 2 of the constant inverter power supply method ((a) always, (b) when a power failure occurs).

  Normally, as shown in FIG. 7A, AC power input from the system (for example, commercial power source) 4 to the uninterruptible power supply 2 is once converted into DC power by a converter CNV, and this DC power is converted into an inverter. (For example, a constant voltage constant frequency inverter) It is converted into AC power synchronized with the system 4 by INV 1 and supplied to the load 6.

  When an instantaneous drop or a power failure occurs in the grid 4, the DC power supply source is immediately switched from the converter CNV to the capacitor 5A as shown in FIG. 7B, and the load power is continuous without being affected by the grid 4. Supplied.

  Note that BC indicates a bypass circuit for supplying electric power that is input directly during maintenance and inspection of the uninterruptible power supply or in the event of a failure. The direct input is a commercial AC power source or an AC power source different from the system 4 such as a private power generation facility.

(2) Continuous commercial power supply system FIG. 8 shows an example of a circuit configuration diagram of the uninterruptible power supply 3 of the continuous commercial power supply system ((a) always, (b) when a power failure occurs).

  Normally, AC power input from the system (for example, commercial power source) 4 to the uninterruptible power supply 3 is supplied to the load 6 via the high-speed switch 7 without being passed through the bidirectional power converter INV2. The At the same time, the AC power output from the high-speed switch 7 is converted into DC power via the bidirectional power converter INV2, and charged to the power storage device 5B. When the storage device 5B is a lead storage battery or the like, floating charging is performed by the bidirectional power converter INV2, and when the storage device 5B is a lithium ion battery or a sodium sulfur battery, the bidirectional power converter INV2 is gate-blocked after completion of charging.

  When an instantaneous drop or power failure occurs in the system 4, as shown in FIG. 8 (b), a DC voltage is discharged from the power storage device 5B, the DC voltage is converted into an AC voltage by the bidirectional power converter INV2, and the load 6 Is supplied with power.

  Note that BS indicates a bypass switch. The AC power output from the system 4 is supplied to the load 6 as it is when the high-speed switch 7 is inspected or in the event of a failure.

JP 2003-70184 A

  However, the uninterruptible power supply units 2 and 3 of the constant inverter power supply method and the constant commercial power supply method have the following problems.

  In the uninterruptible power supply device 2 of the constant inverter feeding system, the converter CNV performs AC-DC conversion, and further, the inverter INV1 performs DC-AC conversion, and the load 6 is fed. Therefore, there are many losses in the power converter (converter CNV, inverter INV1), and the system efficiency is low.

  Further, the continuous power supply type uninterruptible power supply 2 can perform parallel redundant operation, but the constant commercial power supply type uninterruptible power supply 3 cannot perform parallel redundant operation.

  That is, in the uninterruptible power supply 2 of the constant inverter power supply method, as shown in FIG. 9A, when the parallel redundant operation is performed, it is possible to always supply power to the load 6 in cooperation with the inverters INV1 and INV1 ′. is there. Therefore, even if an instantaneous drop or power failure occurs on the system 4 side, power can be supplied to the load 6 without causing a cross current or the like.

  However, as shown in FIG. 9 (b), in the uninterruptible power supply 3 of the always commercial power supply system, when a parallel redundant operation is performed, if a voltage drop or a power failure occurs on the system 4 side, the high-speed switches 7 and 7 ' If they are not cut off at the same time, a double current or a cross current may flow through one high-speed switch 7 (or 7 '). Therefore, the uninterruptible power supply device 3 of the always commercial power supply method cannot perform the parallel redundant operation.

  As described above, it is a problem to provide an uninterruptible power supply system with high system efficiency and redundancy.

  The present invention has been devised in view of the above-described conventional problems, and one aspect thereof is an uninterruptible power supply system that converts DC power stored in an electricity storage device into AC power and supplies it to a load when the system is abnormal. In this case, an uninterruptible power supply device of a constant commercial power supply system and an uninterruptible power supply device of a constant inverter power supply system are connected in series between the system and the load.

  In another aspect of the present invention, the uninterruptible power supply of the always commercial power supply system includes a switching unit that switches supply / cutoff of power from a system, a bypass switch connected in parallel to the switching unit, A first power storage device connected to the output side of the switching means, and a bidirectional power converter interposed between the switching means and the first power storage device are provided.

  According to another aspect of the present invention, the uninterruptible power supply of the continuous inverter power supply system includes a converter that converts alternating current power input from the uninterruptible power supply apparatus of the continuous commercial power supply system into direct current power, and system power from the direct current power. An inverter that obtains AC power synchronized with the inverter, a second power storage device that supplies a DC voltage to the inverter, a bypass circuit that bypasses a power conversion unit that includes the converter and the inverter, and power supply to the load from the bypass circuit Alternatively, a bypass switching circuit that switches power supply from the inverter to the load without interruption is provided.

  According to another aspect of the present invention, during normal operation, the selection switch is connected to the bypass circuit side, and AC power output from an uninterruptible power supply of a commercial power supply system is always supplied to the load via the bypass circuit. It is characterized by.

  According to another aspect of the present invention, the selection switch is connected to the bypass circuit side at the time of inspection or failure of the continuous inverter power supply type uninterruptible power supply, and power is supplied to the load by the continuous commercial power supply type uninterruptible power supply. It is characterized by compensating.

  Another aspect of the present invention is characterized in that a bypass switch is turned on at the time of inspection or failure of an uninterruptible power supply system of a constant commercial power supply system, and the power supply to the load is compensated by the uninterruptible power supply apparatus of a constant inverter power supply system. And

  According to the present invention, it is possible to provide an uninterruptible power supply system with high system efficiency and redundancy.

The circuit block diagram which shows an example of the uninterruptible power supply system in embodiment. The circuit block diagram which shows operation | movement of the uninterruptible power supply system at the time of normal operation. The circuit block diagram which shows operation | movement of the uninterruptible power supply system at the time of a sag or a power failure. The circuit block diagram which shows operation | movement of the uninterruptible power supply system at the time of a sag or a power failure. The circuit block diagram which shows operation | movement of the uninterruptible power supply system at the time of a momentary drop or a power failure recovery. The circuit block diagram which shows operation | movement of the uninterruptible power supply system at the time of a momentary drop or a power failure recovery. The circuit block diagram which shows an example of the uninterruptible power supply in the conventional continuous inverter electric power feeding system. The circuit block diagram which shows an example of the uninterruptible power supply in the conventional regular commercial power supply system. The circuit block diagram which shows an example of the uninterruptible power supply in the conventional parallel redundant system.

  The uninterruptible power supply system of the present invention is a series of an always-inverter-powered uninterruptible power supply and a continuous-commercial-powered uninterruptible power supply in order to provide a system with high system efficiency and redundancy. Connected.

[Embodiment]
The uninterruptible power supply system 1 of this embodiment is demonstrated based on FIG. An uninterruptible power supply system 1 according to the present embodiment includes an uninterruptible power supply device (hereinafter referred to as a commercial power supply unit) 3 of a constant commercial power supply system and a continuous inverter between a system (for example, a commercial power supply) 4 and a load 6. A power supply type uninterruptible power supply (hereinafter referred to as an inverter power supply unit) 2 is connected in series.

  The commercial power supply unit 3 is composed of a main circuit equivalent to the conventional continuous commercial power supply type uninterruptible power supply 3, and includes a high-speed switch 7 as a switching means for switching supply / cutoff of power from the system 4, and the high-speed switch A bypass switch BS connected in parallel to the switch 7, a power storage device 5B connected to the output side of the high-speed switch 7, and a bidirectional power conversion interposed between the high-speed switch 7 and the power storage device 5 Instrument INV2.

  1, the anti-parallel connection circuit of the thyristor is shown in FIG. 1, but the high-speed switch 7 can also be configured by another semiconductor switch such as IGBT, transistor, FET, or a combination of a semiconductor switch and a mechanical switch. . The bypass switch BS is turned on at the time of maintenance and inspection of the high-speed switch 7 or in the event of a failure, and the AC power output from the system 4 is supplied to the inverter power supply unit 2 as it is. Examples of the electricity storage device 5 include a lead storage battery, a lithium ion battery, and a sodium sulfur battery. The bidirectional power converter INV2 has an AC-DC conversion function (that is, a converter function) and a DC-AC conversion function (that is, an inverter function).

  The constant inverter power supply unit 2 is composed of a main circuit equivalent to the conventional uninterruptible power supply device 2 of a conventional constant inverter power supply method, and a converter CNV that converts AC power input from the commercial power supply unit 3 into DC power; The inverter INV1 that obtains AC power synchronized with the system 4 power from the DC power, the power storage device 5A interposed between the converter CNV and the inverter INV1, and the power conversion unit including the converter CNV and the inverter INV1 are bypassed. And a bypass switching circuit 8 that switches power supply to the load 6 from the bypass circuit BC or power supply to the load 6 from the inverter INV1 without interruption.

  The bypass switching circuit 8 includes a thyristor switch TS as a semiconductor switch, and a selection switch SW connected in parallel to the thyristor switch TS.

  Hereinafter, the operation procedure of the uninterruptible power supply system 1 at the time of (1) normal operation, (2) at the time of a voltage drop or power failure, and (3) at the time of a voltage drop or power failure recovery will be described with reference to FIGS. Here, it is assumed that the occurrence of an instantaneous voltage drop or a power failure occurs on the system 4 side.

(1) During normal operation As shown in FIG. 2, the high-speed switch 7 of the commercial power supply unit 3 is turned on, and the selection switch SW of the inverter power supply unit 2 is connected to the bypass circuit BC side. At this time, the bypass switch BS of the commercial power supply unit 3 is opened, and the thyristor switch TS of the inverter power supply unit 2 is set to OFF control.

  As a result, AC power input from the system 4 to the commercial power supply unit 3 is output to the inverter power supply unit 3 via the high-speed switch 7. At this time, the AC power output from the high-speed switch 7 is also output to the bidirectional power converter INV2, and is converted into DC power by the bidirectional power converter INV2 to be charged in the power storage device 5B. Here, when the power storage device 5B is a lead storage battery or the like, floating charging is performed by the bidirectional power converter INV2, and when the storage device 5B is a lithium ion battery or a sodium sulfur battery, the bidirectional power converter INV2 is Gate blocked.

  The AC power input to the inverter power supply unit 2 is supplied to the load 6 via the bypass circuit BC and the selection switch SW.

(2) In case of instantaneous drop or power failure (2) -1
As shown in FIG. 3, the high speed switch 7 of the commercial power supply unit 3 is controlled to be OFF. At this time, the bypass switch BS is opened and the selection switch SW is left connected to the bypass circuit BC.

  As a result, the DC voltage discharged from the power storage device 5 of the commercial power supply unit 2 is converted into an AC voltage by the bidirectional power converter INV2 and output to the inverter power supply unit 2. The AC power input to the inverter power supply unit 2 is supplied to the load 6 via the bypass circuit BC and the selection switch SW. In other words, when the instantaneous drop or power failure occurs in the system 4, power is supplied to the load 6 by a constant commercial power supply method.

(2) -2
Then, the inverter INV1 of the inverter power supply unit 2 is activated while the commercial power supply unit 2 compensates the power supply to the load 6. Here, since the selection switch SW remains connected to the bypass circuit BC, power supply from the inverter INV1 to the load 6 is cut off.

(2) -3
Next, as shown in FIG. 4, the inverter INV1 output voltage of the inverter power supply unit 2 and the output voltage of the commercial power supply unit 3 are synchronized, the thyristor switch TS is turned on, and the selection switch SW is turned to the inverter INV1 side. Switch.

  Thereby, the AC power input from the commercial power supply unit 3 to the inverter power supply unit 2 is output to the load 6 via the bypass circuit BC and the thyristor switch TS. Further, the DC voltage discharged from the electricity storage device 5A is converted into an AC voltage by the inverter INV1, and supplied to the load 6 through the selection switch SW. At this time, the AC voltage from the bypass circuit BC (commercial power feeding unit 3) and the AC voltage from the inverter INV1 are synchronized as described above.

(2) -4
Thereafter, the thyristor switch TS is controlled to be OFF, and the AC output from the bypass circuit BC is cut off.

  As described above, the AC voltage of the commercial power supply unit 3 and the inverter power supply unit 2 is synchronized by the operation procedure of (2) -2 to 4, and the power supply to the load 6 is switched from the commercial power supply unit 3 to the inverter power supply unit 2. It is done.

(3) When instantaneous drop or power failure is restored (3) -1
As shown in FIG. 5, when the instantaneous drop or power failure in the grid 4 is restored, the AC voltage output from the power storage device 5B via the bidirectional power converter INV2 is synchronized with the grid 4 voltage, and the high speed switch 7 is turned ON.

  As a result, the AC voltage output from the system 4 is output to the inverter power supply unit 2 via the high-speed switch 7. As a result, the output to the inverter power supply unit 2 is switched from the power storage device 5B and bidirectional power converter INV2 side to the system 4 and high-speed switch 7 side.

  Here, when the electricity storage device 5B is a lead storage battery or the like, floating charging is performed by the bidirectional power converter INV2. When the power storage device 5B is a lithium ion battery, a sodium sulfur battery, or the like, the bidirectional power converter INV2 is gate-blocked after the power storage device 5B is completely charged.

  In the inverter power supply unit 2, the selection switch SW is connected to the inverter INV1 side, and the thyristor switch TS remains in the OFF control. Therefore, in the inverter power supply unit 2, the AC voltage input from the commercial power supply unit 2 is converted into a DC voltage through the converter CNV, converted into an AC voltage by the inverter INV1, and the load 6 is input through the selection switch SW. To be supplied.

(3) -2
As shown in FIG. 6, the output of the inverter power supply unit 2 (output of the inverter INV1) and the output voltage of the system 4 are synchronized, and the thyristor switch TS is controlled to be ON. Thereafter, the selection switch SW is switched to the bypass circuit BC side.

  As a result, the AC output from the inverter INV1 is cut off, and the power supply to the load 6 is switched to the bypass circuit BC side.

(3) -3
Finally, the thyristor switch TS is turned off.

  As a result, power is supplied from the bypass circuit BC to the load 6 via the selection switch SW.

  As a result, the AC power output from the system 4 is output to the inverter power supply unit 2 through the high-speed switch 7, and the inverter power supply unit 2 supplies power to the load 6 through the bypass circuit BC and the selection switch SW. That is, the operation returns to the normal operation.

  According to the present embodiment, the power converter (converter CNV, inverter INV1) of the inverter power supply unit 2 can be brought into a state close to a stop except during the instantaneous voltage drop and the power failure compensation. Reduction can be achieved.

  Moreover, it becomes possible to provide a redundant uninterruptible power supply system by connecting the inverter power supply part 2 and the commercial power supply part 3 in series like this embodiment. In other words, when the commercial power supply unit 3 is inspected or failed, the power supply to the load 6 can always be compensated by turning on the bypass switch BS and starting the inverter power supply unit 2. Further, when the inverter power supply unit 2 is inspected or malfunctioned, the power supply to the load 6 can always be compensated by starting the commercial power supply unit 3 and connecting the selection switch SW to the bypass circuit BC side. As a result, the reliability of the uninterruptible power supply system is improved.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

1 ... Uninterruptible power supply system 2 ... Uninterruptible power supply system with inverter power supply (inverter power supply unit)
3… Uninterruptible power supply system with commercial power supply (commercial power supply unit)
4 ... System 5A, 5B ... Power storage device 6 ... Load 7 ... High speed switch (switching means)
8 ... Bypass switching circuit CNV ... Converter INV1 ... Inverter INV2 ... Bidirectional power converter SW ... Selection switch TS ... Thyristor switch BC ... Bypass circuit BS ... Bypass switch

Claims (6)

An uninterruptible power supply system that converts DC power stored in an electricity storage device into AC power and supplies it to a load when a system abnormality occurs,
An uninterruptible power supply system characterized in that a continuous commercial power supply type uninterruptible power supply unit and a continuous inverter power supply type uninterruptible power supply unit are connected in series between a system and a load. The continuous commercial power supply uninterruptible power supply is
Switching means for switching supply / cutoff of power from the grid,
A bypass switch connected in parallel to the switching means;
A first power storage device connected to the output side of the switching means;
A bidirectional power converter interposed between the switching means and the first power storage device;
The uninterruptible power supply system according to claim 1. The uninterruptible power supply of the constant inverter feeding method is
A converter that converts AC power input from an uninterruptible power supply of a commercial power supply system into DC power;
An inverter for obtaining AC power synchronized with system power from the DC power;
A second power storage device for supplying a DC voltage to the inverter;
A bypass circuit for bypassing the power conversion unit comprising the converter and the inverter;
A bypass switching circuit that switches power supply to the load from the bypass circuit or power supply to the load from the inverter without interruption;
The uninterruptible power supply system according to claim 1 or 2, further comprising: The uninterruptible power supply system according to claim 3,
During normal operation, the selection switch is connected to the bypass circuit side, and the AC power output from the uninterruptible power supply of the commercial power supply system is supplied to the load via the bypass circuit. Control method. The uninterruptible power supply system according to claim 2 or 3,
At the time of inspection or failure of a continuous inverter power supply type uninterruptible power supply device, the selection switch is connected to the bypass circuit side, and the power supply to the load is compensated by the continuous commercial power supply type uninterruptible power supply device. Control method of uninterruptible power supply system. The uninterruptible power supply system according to claim 3,
Control of an uninterruptible power supply system that features a bypass switch to be turned on at the time of inspection or failure of an uninterruptible power supply system that uses a commercial power supply system, and compensates for power supply to the load by an uninterruptible power supply system that uses an inverter power supply system. Method.

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