JP2006006045A - Power supply method and uninterruptible power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply method which is reduced in the difference of a charging time to each power compensating device, regardless of the presence of a variation in the charging capacity of the power compensating devices corresponding to a plurality of UPSes connected in parallel, and can prevent an early trouble and the parallel-off of the UPSes connected to the power compensating device reduced in capacity even in the case of a power loss on a host side, and to provide an uninterruptible power supply system. <P>SOLUTION: Charging states of the power compensating devices 6 are provided to every two uninterruptible power supply systems (1 to n) connected in parallel are detected. Then, power supply sharing to a load 7 is lowered to the uninterruptible power supply system connected to the power compensating device 6 low in charging capacity, whereas the sharing of the other uninterruptible power supply device 2 is increased to compensate the reduction in the sharing to secure power required by the load. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply method and an uninterruptible power supply system in which a plurality of uninterruptible power supply apparatuses are connected in parallel to supply power to a load.

  In recent years, uninterruptible power supplies (hereinafter referred to as UPS) that stably supply high-quality AC power with little voltage fluctuation to an important load such as a computer have been widely used in various industrial fields. This UPS has a rectifier having a charging function, converts a commercial power source into a direct current to charge a power compensation device such as a storage battery, and reversely converts the direct current into an alternating current of a predetermined frequency by an inverter and supplies it to a load. Is. Then, an uninterruptible power supply system in which a plurality of UPSs are connected in parallel to improve reliability has come to be used.

  In such an uninterruptible power supply system, the charging control of the power compensator provided corresponding to each UPS is performed independently in each UPS, and the charging control between the UPSs connected in parallel is performed. Not done.

  In addition, although it is not an uninterruptible power supply system, the invention which aims at speeding up of charge time in charge compensation system and optimization of charge amount has been proposed conventionally (for example, refer to patent documents 1).

  However, charging control between UPSs in an uninterruptible power supply system in which a plurality of UPSs are connected in parallel has not been performed so far.

  By the way, in each UPS constituting the uninterruptible power supply system, the output of the rectifier is the sum of the supply to the load (directly the supply to the inverter) and the charge to the power compensator. The charging current to the compensation device is a difference between the rated capacity of the rectifier and the rated capacity of the UPS provided with the rectifier.

  On the other hand, in such an uninterruptible power supply system, when power loss occurs on the upper side of each UPS due to a power failure of the commercial power supply, etc., based on the DC power that has been charged in the power compensator so far, it is supplied to the load via the inverter. Powered. At this time, even if a plurality of UPSs connected in parallel have a reduced capacity of the power compensation device, the power supply to the load is controlled so that the load is evenly shared by each UPS. . For this reason, a UPS connected to a power compensator having a reduced capacity is fault-disconnected earlier than other UPSs connected in parallel.

  In addition, in the charge control for the UPS power compensation devices connected in parallel, charging is normally performed in preparation for the next power loss on the higher-order side, but the charge capacity of each power compensation device varies. In this case, the current control method causes a difference in the completion of charging.

  FIG. 4 shows a first UPS (hereinafter referred to as UPS (1)) and other UPS (hereinafter referred to as UPS (2-n)) in an uninterruptible power supply system in which n UPSs are connected in parallel. The case where there is variation in the charging capacity is described.

  In FIG. 4A, UPS (2 to n) is almost completely charged to the power compensator and the DC current is a low value, whereas UPS (1) is charged to the corresponding power compensator. Therefore, when the charging is completed after the time T3 has elapsed, the direct current value decreases to the same value as UPS (2 to n).

  FIG. 4B shows the output currents of n UPSs, and since the loads are equally shared by n units in parallel, the output currents of USP (1) and other USPs (2 to n) are It becomes the same value.

  FIG. 4 (c) shows the rectifier current of UPS (1). The power compensation device charging current shown in FIG. 4 (a) and the load current equivalent to the output current shown in FIG. When the time T3 has elapsed and the charging of the power compensator is completed, the rectifier current also decreases.

  On the other hand, at the time of power loss on the upper side, each USP is fed based on DC power from the corresponding power compensation device. At that time, if power compensators with reduced capacities are mixed, the USP to which the power compensators with reduced capacities are connected breaks down earlier than other USPs. The system capacity of the entire uninterruptible power supply system will be reduced.

  FIG. 5 illustrates a case where the capacity of the first UPS (1) is lower than the other UPS (2 to n) in an uninterruptible power supply system in which n UPSs are connected in parallel.

5A shows changes in the DC voltage of each UPS, FIG. 5B shows the state of the output current of each UPS, and FIG. 5C shows the state of the DC current of each UPS. From these figures, UPS (2 to n) having a sufficient capacity of the power compensator has a gradual change in the DC voltage and DC current, but in UPS 1 in which the capacity of the power compensator has decreased, other UPS Compared with (2 to n), the change in the DC voltage and the DC current is large, and the failure is resolved when the time T5 has elapsed. After the failure of UPS (1) is resolved, the share of UPS (1) from which other UPS (2-n) is disconnected will be shared, so as shown in FIG. Their output current increases.
JP 2002-271993 A

  In such an uninterruptible power supply system in which a plurality of UPSs are connected in parallel to supply power to the load, the charge control of each power compensation device is performed individually. If there is a difference, and power is supplied from the power compensator when power is lost on the upper side, the uninterruptible power supply connected to the power compensator whose capacity has been reduced will quickly fail and the capacity of the entire system will be reduced. Occurred.

  The object of the present invention is to reduce the difference in charging time for each power compensator even if there is a variation in charging capacity among the power guarantee devices corresponding to a plurality of UPSs connected in parallel, and the upper power loss. It is an object of the present invention to provide an electric power supply method and an uninterruptible power supply system that can prevent early failure of a UPS connected to a power compensator whose capacity has been reduced.

  The power supply method according to the present invention includes a rectifier that converts alternating current into direct current, and an inverter that reversely converts direct current rectified by the rectifier into alternating current, and a power compensation device is connected to the direct current portion from the rectifier to the inverter. Power supply method for connecting a plurality of uninterruptible power supply devices connected in parallel to supply power to a load, wherein each uninterruptible power supply device is charging a corresponding power compensation device with DC power from a rectifier , Detecting the charge state of each of the power compensators provided for each of the plurality of uninterruptible power supply units during normal operation in which AC power is output from the corresponding inverter and the power required by the load is supplied to each other. For an uninterruptible power supply connected to a power compensation device with a low charging capacity, the power supply to the load is reduced to increase the charging current to the power compensation device. Load decrease by increasing the share of other uninterruptible power supply, characterized in that to secure the electric power demand.

  Further, in the method of the present invention, due to the loss of the upper power of the uninterruptible power supply, each uninterruptible power supply can mutually reduce the power required by the load based on the DC power supplied from the corresponding power compensator to the inverter. At the time of backup operation that is shared and supplied, the charging state of each power compensation device provided for each of the plurality of uninterruptible power supply devices is detected, and the uninterruptible power supply device to which a power compensation device with a low charging capacity is connected is detected. On the other hand, the power supply to the load is reduced to reduce the supply current from the power compensation device, and the power required by the load is secured by increasing the share of the uninterruptible power supply with this reduced share. .

  An uninterruptible power supply system according to the present invention includes a charge state detection unit that monitors a charge state of a power compensation device provided for each of a plurality of uninterruptible power supply units, and a result of detection by the charge state detection unit. For an uninterruptible power supply to which a low power compensator is connected, load sharing control means for lowering the share of power supply to the load and increasing the share of the other uninterruptible power supply to reduce this share is provided. It is characterized by that.

  In the system of the present invention, the charging power detection means may be one that detects the DC current and DC voltage of the power compensation device and determines the charging state based on those values.

  According to the present invention, even if there is variation in the charging capacity of each power compensation device corresponding to a plurality of uninterruptible power supply devices connected in parallel, each power charging capacity can be made uniform in a short period of time, and Even in the event of power loss on the upper side of the uninterruptible power supply, system reliability can be maintained without reducing the system capacity of the uninterruptible power supply system by effectively utilizing the remaining capacity of the entire power compensator .

  Hereinafter, an embodiment of a power supply method and an uninterruptible power supply system according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of an uninterruptible power supply system according to this embodiment. In FIG. 1A, reference numeral 2 denotes a UPS (uninterruptible power supply), which has a rectifier 4 and an inverter 5 having a charging function, and is connected to a corresponding power compensator 6. The input side of the rectifier 4 is connected to an AC power source 1 such as a commercial power source via a circuit breaker 31, and its output side (DC unit) is connected to the input side of the inverter 5. The power compensation device 6 including a storage battery is connected to the DC unit via the circuit breaker 32, is charged by the output current of the rectifier 4, and supplies DC power to the inverter 5 when the upper power source is lost.

  The output side of the inverter 5 is led out of the UPS 2 through the circuit breaker 33, further connected in parallel with other UPS 2 through the circuit breaker 34, and an uninterruptible power supply formed by connecting a plurality (n units) of UPS 2 in parallel. The system is configured. The output end of the uninterruptible power supply system is connected to the load 7 via the circuit breaker 35 and supplies AC power to the load 7.

  In such an uninterruptible power supply system in which a plurality of UPSs 2 are connected in parallel, in order to detect the state of charge of the power compensator 6, the DC voltages V1,... I1,..., In are detected. Further, in order to detect the load sharing amount of each UPS 2, output currents IO1,..., IOn of each UPS 2 are detected.

  These DC voltages V1,..., Vn and DC currents I1,..., In are supplied to the load sharing control means 23 via the DC voltage detection means 21 and the DC current detection means 22 shown in FIG. To be the charging state information of each power compensation device 6. Therefore, the voltage detection means 21 and the current detection means function as a charge state detection means for detecting the charge state of each power compensation device 6. Also, the output currents IO1,..., IOn are also input to the load sharing control means 23 via the output current detection means 24, and become load sharing information for each UPS2.

  As a result of the detection by the charge state detection units 21 and 22, the load sharing control unit 23 lowers the power supply sharing to the load 7 for the UPS 2 to which the power compensation device 6 having a low charge capacity is connected. The decrease is controlled to increase the share of other UPS2. That is, the control signal of the load sharing control unit 23 is output to the rectifier control unit 25 and the inverter control unit 26 of each UPS 2 and controls the load sharing of each UPS 2 as described above.

  In the above configuration, each UPS 2 charges the corresponding power compensator 6 with DC power from the rectifier 4, outputs AC from the corresponding inverter 5, and supplies the power required by the load 7 in a shared manner with each other. In some cases, the state of charge of each power compensator 6 is detected by a DC current value. That is, when the direct currents I1,..., In are low, it means that the power compensation device 6 charged with this low direct current has a high charge capacity. On the other hand, when the direct currents I1,..., In are high, it means that the power compensation device 6 charged with the high direct current has a low charge capacity.

  Since the rectifier 4 is designed with respect to the device rating, the capacity obtained by subtracting the load capacity from the capacity of the rectifier 4 is the capacity for charging the power compensator 6. Therefore, for the UPS 2 having the power compensation device 6 with a low charge capacity, the charge supply to the power compensation device 6 is increased by reducing the power supply share to the load 7. This reduced share secures the power required by the load 7 by increasing the share of the other UPS 2.

  That is, when the detected direct currents I1,..., In are high, it is determined that the charging capacity of the power compensation device 6 is low, and the load sharing control means 23 controls the inverter 5 of the corresponding UPS 2. The load sharing is lowered and the DC current on the primary side of the inverter 5 is reduced. As a result, the current of the rectifier 4 increases the direct current for charging the power compensator 6, thereby shortening the charging time. Further, by controlling the inverter 5 of the other UPS 2 and increasing the load sharing, the necessary power supply to the load 7 is maintained, and the function of the uninterruptible power supply system is maintained.

  FIG. 2 shows the charging of the power compensator 6 connected to the first USP (1) when the direct current of the first USP (1) as the first unit is large in the n uninterruptible power supply systems connected in parallel. It is a time chart showing the example of load sharing control when a capacity | capacitance is low.

  As shown in FIG. 2A, until the time T1, the charge capacity of the first UPS (1) is low, so that the direct current value is larger than the other UPS (2 to n). For this reason, as shown in FIG. 2B, the load sharing (output current) of the first UPS (1) is lowered, and the load sharing (output current) of the other UPS (2 to n) is increased. As a result, as shown in FIG. 2C, the rectifier current of the first USP (1) has a small amount of load current and a large proportion of the power compensator charging current until time T1.

  After time T1, the state of charge of the power compensator 6 connected to the first UPS (1) 2 is improved, and after time T2 when charging is completed, the load sharing state equivalent to the other UPS (2-n) Become.

  Thus, the DC current and DC voltage to each power compensation device 6 in each UPS (1 to n) 2 connected in parallel are detected, and the charge capacity is grasped based on the DC current and DC voltage. . When the power compensation device 6 is charged and its charge capacity is low, the load share of the rectifier 4 is reduced by reducing the load sharing of the USP 2 to which the power compensation device 6 is connected. Accordingly, it becomes possible to increase the charging current to the power compensator 6, and the charging time is reduced.

  On the other hand, when power loss occurs on the upper side of each USP 2 due to a power failure or the like of the commercial power supply, each USP 2 supplies DC power from the corresponding power compensator 6 to the inverter 5, and based on this, the power required by the load 7 Backup operation is performed. At this time, since the charging state of the power compensator 6 connected to each UPS 2 is detected, the power supply sharing to the load 7 is shared with respect to the UPS 2 connected to the power compensator 6 having a low charging capacity. The supply current from the corresponding power compensator 6 is decreased to decrease. This reduced share secures the power required by the load 7 by increasing the share of the other UPS 2.

  That is, when the DC voltages V1,..., Vn of the UPSs 2 connected in parallel are detected and the DC voltage is low, it is determined that the remaining capacity of the power compensator 6 is low. Then, the load sharing is reduced by controlling the inverter 5 of the UPS 2 to which the power compensation device 6 is connected, and the DC current on the primary side of the inverter 5 is reduced. Therefore, the burden capacity of the power compensator 6 is also reduced, the discharge time can be extended, and the UPS 2 with a small remaining capacity of the power compensator 6 can secure the same discharge time as the other UPS 2 so that there is no power failure. The system capacity of the entire power supply system is not reduced.

  FIG. 3 shows a time chart of an example of sharing control when the DC voltage of the first USP (1) that is the first unit is low in the n uninterruptible power supply systems connected in parallel.

  That is, since the remaining capacity of the power compensator 6 connected to the first UPS (1) is low, as shown in FIGS. 3A and 3C, the degree of change in the DC voltage and DC current until time T4. Is larger than other UPS (2-n). For this reason, in this state, only the first UPS (1) is quickly fault-disconnected, and the system capacity of the entire uninterruptible power supply system is reduced.

  Therefore, as shown in FIG. 3B, after time T4, the load sharing (output current) of the first UPS (1) is lowered and the load sharing (output current) of the other UPS (2 to n) is increased. As a result, as shown in FIGS. 3A and 3C, the degree of change in the DC voltage and DC current of the first USP (1) becomes gradual and is equivalent to the other UPS (2 to n) at time T6. It becomes a state. In other words, unlike the conventional case, only the first UPS (1) is not quickly disconnected, and the system capacity of the entire uninterruptible power supply system can be maintained over a long period of time.

  Thus, the DC current and DC voltage to each power compensation device 6 in each UPS (1 to n) 2 connected in parallel are detected, and the charge capacity is grasped based on the DC current and DC voltage. . When the power supply on the upper side of the uninterruptible power supply system is lost, each UPS (1 to n) 2 is supplied with power from the corresponding power compensator 6, and at that time, the power compensator 6 having a low charging capacity is connected. As for UPS (1) 2, the discharge time from the power compensator 6 can be matched with other UPS (2 to n) 2 by reducing the load sharing. Therefore, it is possible to avoid a situation in which the UPS (1) 2 breaks down due to a decrease in charge capacity and the system capacity decreases.

1 shows an embodiment of an uninterruptible power supply system according to the present invention, where (a) is a system configuration diagram and (b) is a block diagram of a load sharing control portion. It is a time chart which shows the example of load sharing control at the time of the normal driving | operation in one Embodiment same as the above. It is a time chart which shows the example of load sharing control at the time of the backup driving | operation in one Embodiment same as the above. It is a time chart which shows the example of load sharing control at the time of the conventional normal driving | operation. It is a time chart which shows the example of load sharing control at the time of the conventional backup driving | operation.

Explanation of symbols

2 Uninterruptible power supply (UPS)
4 Rectifier 5 Inverter 6 Power Compensation Device 7 Load 21 DC Voltage Detection Unit 22 Acting as Charging State Monitoring Unit DC Current Detection Unit 23 Acting as Charging State Monitoring Unit Load Sharing Control Unit

Claims (4)

An uninterruptible power supply having a rectifier that converts alternating current into direct current and an inverter that reversely converts direct current rectified by the rectifier into alternating current, and a power compensation device connected to the direct current portion from the rectifier to the inverter, A power supply method for connecting multiple units in parallel and supplying power to a load,
In normal operation, the plurality of uninterruptible power supply units charge the corresponding power compensator with DC power from the rectifier, AC output from the corresponding inverter, and share the power required by the load with each other In
Supplying power to the load for the uninterruptible power supply device that detects the charging state of each power compensation device provided for each of the plurality of uninterruptible power supply devices and connects the power compensation device with a low charge capacity Decreasing the share to increase the charging current to the power compensation device,
A power supply method characterized by securing the power required by the load by increasing the share of the uninterruptible power supply by sharing the reduced share. An uninterruptible power supply having a rectifier that converts alternating current into direct current and an inverter that reversely converts direct current rectified by the rectifier into alternating current, and having a power compensation device connected to the direct current portion from the rectifier to the inverter, A power supply method for connecting multiple units in parallel and supplying power to a load,
Backup operation in which each uninterruptible power supply unit shares the power required by the load with each other based on the DC power supplied from the corresponding power compensator to the inverter due to the loss of upper power of the uninterruptible power supply unit At times
The power compensation device provided for each of the plurality of uninterruptible power supply devices is monitored for charge, and the power supply to the load is supplied to the uninterruptible power supply device connected to the power compensation device having a low charge capacity. Decreasing the share and reducing the supply current from the power compensation device,
A power supply method characterized by securing the power required by the load by increasing the share of the uninterruptible power supply with this share reduction. An uninterruptible power supply having a rectifier that converts alternating current into direct current and an inverter that reversely converts direct current rectified by the rectifier into alternating current, and a power compensation device connected to the direct current portion from the rectifier to the inverter, An uninterruptible power supply system that supplies power to a load by connecting multiple units in parallel,
Charge state detection means for detecting the state of charge of each power compensation device provided for each of the plurality of uninterruptible power supply devices;
As a result of the detection by the charging state detection means, for the uninterruptible power supply device to which the power compensation device having a low charge capacity is connected, the share of power supply to the load is lowered, and this reduced share is reduced to other uninterruptible power supplies. Load sharing control means for increasing the sharing of the device;
An uninterruptible power supply system characterized by comprising   4. The uninterruptible power supply system according to claim 3, wherein the charging power detection means detects a direct current and a direct current voltage of the power compensator and determines the state of charge based on these values.

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