JP2013090524A - Uninterruptible power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an uninterruptible power supply system capable of setting a capacity of an inverter to be smaller to reduce a device in size and cost.SOLUTION: An uninterruptible power supply system comprises: an inverter 7 which inverts a DC input into an AC voltage and outputs the AC voltage; a converter 8 which converts AC power from a commercial power supply 1 into DC power and outputs the DC power to the inverter 7; a detecting circuit 15 for detecting instantaneous interruptions and power interruptions of commercial power supplies 1 and 2; a storage battery 4 for supplying DC power to the inverter 7 at the time of the detection of the instantaneous interruptions; and an uninterruptible switching circuit 13 which supplies the AC power from the commercial power supply 2 to a normal load 6 at the time of normal operation, and when the instantaneous interruptions are detected, supplies the AC power from the inverter 7 to the normal load 6. When the instantaneous interruptions are detected, the inverter 7 performs power supply to an important load 5 and to the normal load 6 by using a region of an overload capacity. When the power interruptions are detected, the uninterruptible switching circuit 13 stops the power supply to the normal load 6.

Description

  The present invention relates to an uninterruptible power supply system used as a backup power supply at the time of a power failure and a voltage drop.

  An important load such as a computer requires a stable and high-quality power source at all times. A momentary power outage is not allowed for critical loads. The important load is required to continue power supply for about 5 to 10 minutes after a power failure occurs. For this reason, an uninterruptible power supply device (hereinafter also referred to as “UPS”) of a constant inverter power feeding system is used as a device for supplying power to an important load.

FIG. 5 is a block diagram showing a conventional uninterruptible power supply of a constant inverter feeding system.
Commercial power supplies 25 and 26 are connected to input terminals 24a and 24b in the UPS 24 of the constant inverter power feeding system. A storage battery 27 is connected to the external terminal 24 c of the UPS 24. An important load 28 is connected to the output terminal 24 d of the UPS 24.

  In the UPS 24, AC power from the commercial power supply 25 is normally input to the converter 30 via the AC input circuit breaker 29. Converter 30 converts AC power from commercial power supply 25 into DC power and outputs it to inverter 31. Inverter 31 reversely converts the DC power from converter 30 into AC power and outputs it to uninterruptible switching circuit 32. In the uninterruptible switching circuit 32, the semiconductor switch 33 is turned off and the contactor 34 is turned on to supply the AC power from the inverter 31 to the important load 28.

  Reference numeral 35 denotes a bypass circuit connected to the input terminal 24b and the semiconductor switch 33 of the uninterruptible switching circuit 32, and reference numeral 36 denotes a bypass input circuit breaker provided in the bypass circuit 35. When the converter 30 or the inverter 31 breaks down, the uninterruptible switching circuit 32 switches the semiconductor switch 33 to ON and the contactor 34 to OFF to supply AC power from the commercial power supply 26 to the important load 28.

  When a power failure occurs in the commercial power sources 25 and 26, the converter 30 is stopped and the DC power from the storage battery 27 is supplied to the inverter 31 via the DC circuit breaker 37. Electric power is supplied to the important load 28 from the inverter 31 side even during normal times. For this reason, the uninterruptible switching circuit 32 does not perform any switching operation even if a power failure occurs. Even if a power failure occurs in the commercial power supplies 25 and 26, the important load 28 is continuously supplied with power from the inverter 31 side.

  On the other hand, a normal load such as an air conditioner that is ancillary equipment of a computer is not particularly required for the quality of the power source. Generally, commercial power is supplied to the normal load. For normal loads, there is no requirement for continuous power supply during a power failure, but when an instantaneous voltage drop (hereinafter also referred to as “instantaneous voltage drop”) occurs, power is supplied. There is a request to continue. For this reason, as a device for supplying power to a normal load, a commercial power supply type instantaneous drop compensation device (hereinafter also referred to as “SPS”) is used.

FIG. 6 is a block diagram showing a conventional sag compensator of a conventional commercial power supply system.
The commercial power supply 25 and 26 are connected to the input terminals 38a and 38b in the SPS 38 of the constant commercial power supply system. A storage battery 27 is connected to the external terminal 38 c of the SPS 38. A normal load 39 is connected to the output terminal 38d of the SPS 38.

  In the SPS 38, AC power from the commercial power supply 26 is normally input to the uninterruptible switching circuit 41 via the bypass circuit 40. Reference numeral 42 denotes a bypass input circuit breaker provided in the bypass circuit 40. In the uninterruptible switching circuit 41, the semiconductor switch 43 is turned on and the semiconductor switch 44 is turned off, so that AC power from the commercial power supply 26 is supplied to the normal load 39.

  In the SPS 38, AC power from the commercial power supply 25 is normally input to the converter 46 via the AC input circuit breaker 45. The converter 46 converts AC power from the commercial power supply 25 into DC power and supplies it to the storage battery 27. Thereby, the storage battery 27 is charged.

  When an instantaneous drop occurs in the commercial power supplies 25 and 26, DC power from the storage battery 27 is supplied to the inverter 48 via the DC circuit breaker 47. In the non-instantaneous switching circuit 41, the semiconductor switch 43 is turned off and the semiconductor switch 44 is turned on to supply AC power from the inverter 48 to the normal load 39.

  As shown in the example of the computer and the air conditioner, the UPS and the SPS are generally used in the same system. For example, in a load facility such as a production line, a UPS is used as a power source for controlling the production line in terms of performance. SPS is used as a power source for power equipment and air-conditioning equipment in consideration of operation and economy.

  Patent Document 1 below proposes a power supply device that performs power failure compensation for loads such as computers and peripheral devices (see, for example, FIG. 8 of Patent Document 1).

JP-A-11-215738

  Conventional power supply devices including those described in Patent Document 1 have a problem that the configuration becomes complicated and large in size and expensive when the functions of both UPS and SPS are used in the same system. For example, in the device described in Patent Document 1, the capacity of the inverter must be set in consideration of both the capacity required for important loads such as computer equipment and the capacity for normal loads such as air conditioning equipment. For this reason, there existed a problem that an inverter enlarged and a system became expensive.

  The present invention has been made to solve the above-described problems. The purpose of the present invention is to reduce the capacity of an inverter even when both UPS and SPS functions are used in the same system. An object of the present invention is to provide an uninterruptible power supply system that can reduce the size and cost of the apparatus.

  The uninterruptible power supply system according to the present invention includes an inverter that converts a direct current input into alternating current and outputs, a converter that converts alternating current power from a commercial power source into direct current power, and outputs the direct current to the inverter. A first uninterruptible switching circuit that supplies AC power from a commercial power source to the critical load when a predetermined abnormality occurs in the inverter or converter when power is supplied to the critical load, and detects an instantaneous drop and a power failure of the commercial power source When an instantaneous drop in the commercial power supply is detected by the detection circuit and the detection circuit, the energy storage unit that supplies DC power to the inverter and the AC power from the commercial power supply are normally supplied to the normal load, and the commercial power is supplied by the detection circuit. And a second uninterruptible switching circuit that supplies AC power from the inverter to a normal load when an instantaneous power supply drop is detected. When an instantaneous power supply drop is detected, power is supplied to the critical load and normal load using the overload capacity range, and the second uninterruptible switching circuit detects a power failure of the commercial power supply by the detection circuit. Then, the power supply to the normal load is stopped.

  With the uninterruptible power supply system according to the present invention, even if both UPS and SPS functions are used in the same system, the capacity of the inverter can be set small, and the apparatus can be reduced in size and cost. .

It is a block diagram which shows the uninterruptible power supply system in Embodiment 1 of this invention. It is a figure for demonstrating operation | movement of the uninterruptible power supply system shown in FIG. It is a figure for demonstrating operation | movement of the uninterruptible power supply system shown in FIG. It is a figure for demonstrating operation | movement of the uninterruptible power supply system shown in FIG. It is a block diagram which shows the conventional uninterruptible power supply of a conventional inverter electric power feeding system. It is a block diagram which shows the conventional sag compensator of the usual commercial electric power feeding system.

  The present invention will be described in detail with reference to the accompanying drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals. The overlapping description is simplified or omitted as appropriate.

Embodiment 1 FIG.
1 is a block diagram showing an uninterruptible power supply system according to Embodiment 1 of the present invention.
In FIG. 1, 1 is a commercial power source for AC input, and 2 is a commercial power source for bypass input. The commercial power supply 1 is connected to the input terminal 3 a of the power supply device 3. The commercial power supply 2 is connected to the input terminal 3 b of the power supply device 3. Reference numeral 4 denotes a storage battery including an energy storage unit. The storage battery 4 is connected to the external terminal 3 c of the power supply device 3.

5 is an important load, and 6 is a normal load. The important load 5 requires a stable and high-quality power source at all times. The important load 5 requires continuation of power supply even when a power failure occurs. The important load 5 is connected to the output terminal 3 d of the power supply device 3.
The normal load 6 does not particularly require the quality of the power supply, but requests the continuation of the power supply when an instantaneous drop occurs. The normal load 6 is connected to the output terminal 3 e of the power supply device 3.

  The important load 5 and the normal load 6 are provided in the same system. For example, in a computer facility, the computer equipment is the important load 5, and the air conditioning equipment for air conditioning the computer room is the normal load 6. In the production line, the control device of the production apparatus is the important load 5, and the power device, the air conditioning equipment, and the like are the normal load 6.

  The power supply device 3 includes an inverter 7, a converter 8, an AC input circuit breaker 9, a DC circuit breaker 10, an uninterruptible switching circuit 11, a bypass input circuit breaker 12, an uninterruptible switching circuit 13, a bypass input circuit breaker 14, and a detection circuit. 15 is provided.

The inverter 7 converts the direct current input into alternating current and outputs it.
Converter 8 converts AC power supplied from commercial power supply 1 via input terminal 3 a into DC power and outputs the DC power to inverter 7. When the DC power is supplied from the converter 8, the inverter 7 converts the DC power into AC power and outputs it to the uninterruptible switching circuits 11 and 13.

  The AC input circuit breaker 9 is connected between the input terminal 3 a and the converter 8. If the AC input circuit breaker 9 is closed, AC power from the commercial power source 1 is input to the converter 8. When the AC input circuit breaker 9 is opened, AC power is not supplied from the commercial power source 1 to the converter 8.

  The DC circuit breaker 10 is connected between the external terminal 3 c and the inverter 7. If the DC circuit breaker 10 is closed, DC power from the storage battery 4 is input to the inverter 7 via the external terminal 3c. When the DC power is supplied from the storage battery 4, the inverter 7 converts the DC power into AC power and outputs it to the uninterruptible switching circuits 11 and 13. When the DC breaker 10 is opened, DC power is not supplied from the storage battery 4 to the inverter 7.

  The uninterruptible switching circuit 11 selectively outputs the AC power from the inverter 7 and the AC power from the commercial power source 2 to the important load 5. The uninterruptible switching circuit 11 includes a switching contactor 16 and a semiconductor switch 17. The contactor 16 is connected between the inverter 7 and the output terminal 3d. The AC power output from the inverter 7 is supplied to the important load 5 through the contactor 16.

  The semiconductor switch 17 is connected between the bypass circuit 18 and the output terminal 3d. The bypass input circuit breaker 12 is provided in the bypass circuit 18. That is, the bypass input circuit breaker 12 is connected between the input terminal 3 b and the semiconductor switch 17. If the bypass input circuit breaker 12 is closed, AC power from the commercial power source 2 is input to the semiconductor switch 17 via the bypass circuit 18. When the bypass input circuit breaker 12 is opened, AC power is not supplied from the commercial power source 2 to the semiconductor switch 17.

  The uninterruptible switching circuit 13 selectively outputs AC power from the inverter 7 and AC power from the commercial power source 2 to the normal load 6. The uninterruptible switching circuit 13 includes switching semiconductor switches 19 and 20. The semiconductor switch 19 is connected between the inverter 7 and the output terminal 3e. The AC power output from the inverter 7 is supplied to the normal load 6 through the semiconductor switch 19.

  The semiconductor switch 20 is connected between the bypass circuit 21 and the output terminal 3e. The bypass input circuit breaker 14 is provided in the bypass circuit 21. That is, the bypass input circuit breaker 14 is connected between the input terminal 3 b and the semiconductor switch 20. If the bypass input circuit breaker 14 is closed, AC power from the commercial power source 2 is input to the semiconductor switch 20 via the bypass circuit 21. When the bypass input circuit breaker 14 is opened, AC power is not supplied from the commercial power supply 2 to the semiconductor switch 20.

  The detection circuit 15 (detection means) has a function of detecting an instantaneous drop of the commercial power supplies 1 and 2. For example, when the AC voltage (AC input 1a) input to the input terminal 3a does not reach a predetermined value, the detection circuit 15 detects an instantaneous drop of the commercial power supply 1. In addition, the detection circuit 15 causes the commercial power supply 1 to fail when a state where the AC voltage supplied from the commercial power supply 1 does not reach a predetermined value (for example, a state where an instantaneous drop of the commercial power supply 1 is detected) continues for a predetermined time. To detect.

  Similarly, the detection circuit 15 detects an instantaneous drop of the commercial power supply 2 when the AC voltage (AC input 2a) input to the input terminal 3b does not reach a predetermined value. The detection circuit 15 detects a power failure of the commercial power source 2 when a state where the AC voltage supplied from the commercial power source 2 is less than a predetermined value (for example, a state where an instantaneous drop of the commercial power source 2 is detected) continues for a predetermined time. .

  In the power supply device 3 having the above-described configuration, the inverter 7 is provided with a capacity necessary for stably supplying power to the important load 5. However, when setting the capacity of the inverter 7, the capacity for supplying stable power to the normal load 6 is not taken into consideration. For example, the capacity of the inverter 7 is set based only on the capacity required for the important load 5. For this reason, the capacity of the inverter 7 is smaller than the combined capacity of the capacity required for the continuous operation of the important load 5 and the capacity required for the continuous operation of the normal load 6.

  2 to 4 are diagrams for explaining the operation of the uninterruptible power supply system shown in FIG. The operation of the uninterruptible power supply system having the above configuration will be specifically described below with reference to FIGS.

FIG. 2 shows a power supply path when the commercial power supply 1 and the power supply device 3 are operating normally.
When the commercial power source 1 and the power supply device 3 are operating normally, the AC input 1 a from the commercial power source 1 is input to the converter 8 via the AC input circuit breaker 9. Converter 8 converts AC power from commercial power supply 1 into DC power and outputs the DC power to inverter 7.

  The inverter 7 converts the DC power from the converter 8 back to AC power and outputs it to the uninterruptible switching circuit 11. The uninterruptible switching circuit 11 supplies the AC power from the inverter 7 to the important load 5 via the contactor 16. Under normal conditions, the uninterruptible switching circuit 11 turns the contactor 16 on and the semiconductor switch 17 off. For this reason, a high-quality power source (AC output 22) can be supplied to the important load 5 via the converter 8 and the inverter 7.

  The AC input 2 a from the commercial power source 2 is input to the uninterruptible switching circuit 13 via the bypass circuit 21. The uninterruptible switching circuit 13 supplies AC power from the commercial power supply 2 to the normal load 6 via the semiconductor switch 20. During normal times, the uninterruptible switching circuit 13 turns on the semiconductor switch 20 and turns off the semiconductor switch 19. For this reason, a high-efficiency power source (AC output 23) that does not pass through the converter 8 and the inverter 7 can be supplied to the normal load 6.

  When a failure (predetermined abnormality) occurs in the converter 8 or the inverter 7 at the normal time when the above control is performed, the bypass input circuit breaker 12 is turned on to configure the bypass circuit 18. The uninterruptible switching circuit 11 switches the output source of the AC output 22 from the contactor 16 to the semiconductor switch 17 without an instantaneous disconnection, and supplies the AC load from the commercial power source 2 to the important load 5. That is, when a failure occurs in the converter 8 or the like, the uninterruptible switching circuit 11 turns off the contactor 16 and turns on the semiconductor switch 17. The uninterruptible switching circuit 11 performs this switching without instantaneous disconnection. For this reason, the uninterruptible switching circuit 11 employs a semiconductor switch 17 as switching means on the bypass circuit 18 side.

  Thereafter, when the converter 8 and the like are normalized, the uninterruptible switching circuit 11 switches the output source of the AC output 22 from the semiconductor switch 17 to the contactor 16. When the power supply for the important load 5 is returned from the bypass circuit 18 side to the inverter 7 side, switching is performed so that the inverter 7 wraps in synchronization with the power supply on the bypass circuit 18 side. For this reason, it is not necessary to provide the semiconductor switch which can be turned on and off at high speed on the inverter 7 side of the uninterruptible switching circuit 11. In the uninterruptible switching circuit 11, a contactor 16 is employed as switching means on the inverter 7 side.

FIG. 3 shows a power feeding path when an instantaneous drop occurs in the commercial power sources 1 and 2.
When the AC voltage supplied from the commercial power sources 1 and 2 is reduced to a predetermined value, the detection circuit 15 detects an instantaneous drop in the commercial power sources 1 and 2. When the instantaneous drop of the commercial power supplies 1 and 2 is detected by the detection circuit 15, the converter 8 is stopped and the DC power from the storage battery 4 is supplied to the inverter 7. The important load 5 is supplied with power from the inverter 7 side even during normal times. For this reason, the non-instantaneous switching circuit 11 does not perform any switching operation even if the detection circuit 15 detects the instantaneous drop of the commercial power supplies 1 and 2. The important load 5 is continuously supplied with power from the inverter 7 side even after the commercial power supplies 1 and 2 are instantaneously reduced.

  On the other hand, the uninterruptible switching circuit 13 switches the output source of the AC output 23 from the semiconductor switch 20 to the semiconductor switch 19 when the instantaneous drop of the commercial power supplies 1 and 2 is detected by the detection circuit 15. AC power is supplied to the normal load 6. That is, the uninterruptible switching circuit 13 turns off the semiconductor switch 20 and turns on the semiconductor switch 19 when the AC voltage supplied from the commercial power supplies 1 and 2 becomes a predetermined value or less. For this reason, when an instantaneous drop occurs in the commercial power supplies 1 and 2, AC power obtained by converting DC power from the storage battery 4 in the inverter 7 is supplied to the normal load 6 via the semiconductor switch 19.

  Thereafter, when the AC voltage supplied from the commercial power supplies 1 and 2 exceeds a predetermined value and returns to a normal state (the state of instantaneous voltage drop (voltage drop) is eliminated), the power supply source to the inverter 7 becomes a storage battery. 4 returns to the commercial power source 1. That is, the uninterruptible switching circuit 13 turns on the semiconductor switch 20 and turns off the semiconductor switch 19 to switch the output source of the AC output 23 from the semiconductor switch 19 to the semiconductor switch 20.

  The uninterruptible switching circuit 13 must switch the output source of the AC output 23 in a short time when the instantaneous drop occurs and when power is restored after the instantaneous drop occurs. Therefore, the uninterruptible switching circuit 13 employs semiconductor switches 19 and 20 as switching means on the inverter 7 side and bypass circuit 21 side.

  When detecting the instantaneous drop of the commercial power supplies 1 and 2, the detection circuit 15 measures the duration of the state (a state where the AC voltage from the commercial power supplies 1 and 2 is less than a predetermined value). The detection circuit 15 detects a power failure of the commercial power supplies 1 and 2 when the voltage drop state continues for a predetermined time (for example, 1 second) or longer.

FIG. 4 shows a power supply path when a power failure occurs in the commercial power supplies 1 and 2.
When the voltage drop of the commercial power supplies 1 and 2 continues for a predetermined time or more and a power failure is detected by the detection circuit 15, the uninterruptible switching circuit 13 stops the power supply to the normal load 6. That is, the uninterruptible switching circuit 13 switches the semiconductor switch 19 from ON to OFF.

  In this way, for the normal load 6, power supply compensation is performed only when a voltage sag occurs, and power supply is stopped during a power failure. As described above, when an instantaneous drop occurs in the commercial power supplies 1 and 2, AC power is supplied to both the important load 5 and the normal load 6 via the inverter 7. However, the inverter 7 is not provided with a capacity for stably operating both the important load 5 and the normal load 6 continuously. For this reason, when the voltage drop is detected by the detection circuit 15, the inverter 7 uses the overload withstand area until the power failure is detected by the detection circuit 15. Supply power.

  For example, the inverter 7 has an overload capacity of 125% for 10 minutes or 150% for 1 minute. The capacity of the inverter 7 is basically set based only on the capacity necessary for continuously operating the important load 5. For this reason, with respect to the normal load 6, the capacity is set such that the operation can be performed using the region of the overload capacity of the inverter 7 when an instantaneous drop occurs.

  Since the power supply to the normal load 6 after the occurrence of the sag is performed using the region of the overload capacity of the inverter 7, it cannot be continuously performed. For this reason, when the voltage drop of the commercial power supplies 1 and 2 continues, the power supply to the normal load 6 is stopped and only the power supply to the important load 5 is continued.

  The uninterruptible switching circuit 11 does not perform any switching operation even when the detection circuit 15 detects a power failure of the commercial power supplies 1 and 2. The uninterruptible switching circuit 11 is connected to the inverter 7 through the contactor 16 until the voltage of the storage battery 4 drops below the allowable voltage of the inverter 7 even after the detection circuit 15 detects the power failure of the commercial power supplies 1 and 2. Is supplied to the important load 5.

  In the case of the uninterruptible power supply system having the above-described configuration, both the functions of the conventional UPS alone and the functions of the SPS alone are provided in one power supply device 3 without increasing the capacity of the converter (converter 8 and inverter 7). Can be realized. Moreover, in the power supply device 3, the elements of the conventional UPS and SPS can be shared. For this reason, the apparatus can be reduced in size and the apparatus can be configured at low cost.

1, 2, 25, 26 Commercial power supply 1a, 2a AC input 3 Power supply device 3a, 3b Input terminal 3c External terminal 3d, 3e Output terminal 4, 27 Storage battery 5, 28 Critical load 6, 39 Normal load 7, 31, 48 Inverter 8, 30, 46 Converter 9, 29, 45 AC input circuit breaker 10, 37, 47 DC circuit breaker 11, 13, 32, 41 Uninterruptible switching circuit 12, 14, 36, 42 Bypass input circuit breaker 15 Detection circuit 16 , 34 Contactor 17, 19, 20, 33, 43, 44 Semiconductor switch 18, 21, 35, 40 Bypass circuit 22, 23 AC output 24 UPS
24a, 24b Input terminal 24c External terminal 24d Output terminal 38 SPS
38a, 38b Input terminal 38c External terminal 38d Output terminal

Claims (4)

An inverter that converts direct current input to alternating current and outputs;
A converter that converts AC power from a commercial power source into DC power and outputs the DC power to the inverter;
A first uninterruptible switching circuit for supplying AC power from the inverter to an important load at a normal time and supplying AC power from a commercial power source to the important load when a predetermined abnormality occurs in the inverter or the converter; ,
A detection circuit for detecting an instantaneous drop and a power failure of the commercial power supply;
When an instantaneous drop in commercial power is detected by the detection circuit, an energy storage unit that supplies DC power to the inverter;
A second uninterruptible switching for supplying AC power from a commercial power source to a normal load during normal time and supplying AC power from the inverter to the normal load when the detection circuit detects an instantaneous drop in the commercial power source Circuit,
With
The inverter is configured to supply power to the important load and the normal load using an overload withstand area when an instantaneous drop in commercial power is detected by the detection circuit,
The second uninterruptible switching circuit is an uninterruptible power supply system that stops power supply to the normal load when a power failure of a commercial power source is detected by the detection circuit.   2. The uninterruptible power supply system according to claim 1, wherein the inverter has a capacity that is smaller than a combined capacity of a capacity required for the continuous operation of the important load and a capacity required for the continuous operation of the normal load.   The uninterruptible power supply system according to claim 1, wherein the detection circuit detects a power failure of the commercial power supply when a state for detecting an instantaneous drop of the commercial power supply continues for a predetermined time.   The uninterruptible power supply system according to claim 1 or 2, wherein the detection circuit detects a power failure of the commercial power supply when a state where the AC voltage supplied from the commercial power supply does not reach a predetermined value continues for a predetermined time.

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