JP4498290B2 - Uninterruptible power supply system - Google Patents

Description

  The present invention relates to an uninterruptible power supply system composed of a plurality of uninterruptible power supplies, and more specifically, a plurality of uninterruptible power supplies equipped with a switching circuit for switching to a commercial power supply without interruption. An uninterruptible power supply system that is operated in parallel on a stand is provided with a synchronous control circuit that synchronizes the output of each uninterruptible power supply.

  An uninterruptible power supply device having a switching circuit for switching to a commercial power supply without instantaneous interruption includes a commercial synchronous control circuit for generating an AC output synchronized with the commercial power supply. Further, in order to construct a highly reliable uninterruptible power supply system, a plurality of uninterruptible power supply apparatuses are also operated in parallel. In such a parallel system, for the purpose of improving the reliability of the commercial synchronization control circuit, there is a method of switching the reference voltage to be synchronized to the reference voltage of another machine when the reference voltage of the own machine becomes abnormal. It is disclosed (for example, see Patent Document 1).

  An uninterruptible power supply always operates in synchronization with a commercial power supply, but generally a synchronous tracking range is provided for the commercial frequency, and this tracking range is within a few percent of the rated frequency. Is set. When deviating from this follow-up range, a self-running operation is performed at a fixed frequency (the rated frequency of the commercial power supply) generated by the internal oscillation circuit as in the case of a commercial power supply power failure. This is shown in FIG. FIG. 6 is a timing chart for explaining the frequency tracking operation of the uninterruptible power supply. As shown in FIG. 6, if the commercial power supply frequency is within the frequency tracking range, the output frequency / phase of the uninterruptible power supply is operated in synchronism with the commercial, but if the commercial power supply frequency deviates from the frequency tracking range, Carry out self-propelled operation so that the rated frequency becomes. This operation is the same in the parallel system. In particular, in the parallel system, it is necessary to match the output voltage phases of the respective uninterruptible power supply devices.

JP 2004-336856 A

However, in the commercial synchronization control circuit according to the prior art disclosed in Patent Document 1, since the phase synchronization is always performed by each commercial reference voltage, when the frequency is disturbed, the commercial synchronization control circuit self-runs with the commercial synchronization device. There is a possibility that excessive cross current will occur due to the mixing of devices. The case where the frequency is disturbed, liable when the power supply from the generator to the uninterruptible power supply, also, in the uninterruptible power system where high reliability is required, in case the commercial power source is prolonged power failure, no In many cases, a system that switches the AC input to the power failure power supply from a commercial power source to a private generator is used (see FIG. 1 according to the present invention described later), so the timing of commercial synchronization and self-running is shifted between the devices. In such a case, there is a risk that a cross current will occur and parallel operation will not be possible. In addition to frequency disturbances, there are cases where commercial synchronous operation and self-running operation are switched during a power failure or power recovery of the commercial power supply. There is a risk that cross current will occur and parallel operation will not be possible.

  The present invention has been made to solve the above-described problems, and switches between commercial synchronous operation and self-running operation due to a transient state such as a power failure of a commercial power source, a power recovery, or a commercial power source frequency disturbance. In this case, it is possible to prevent the cross current from flowing between the uninterruptible power supplies, and to continue the commercial synchronous operation even when the commercial synchronous reference voltage of the specific uninterruptible power supply becomes abnormal. The object is to obtain an uninterruptible power supply system with improved system reliability.

An uninterruptible power supply system according to the present invention is an uninterruptible power supply system in which a plurality of uninterruptible power supply devices each having a switching circuit for switching to a commercial power supply without interruption are operated in parallel. The power supply unit becomes the master and performs reference output voltage phase control, and the remaining uninterruptible power supply unit performs slave operation that operates to perform phase synchronization by current control by cross current flowing between the uninterruptible power supply units. and means for setting an identifiable number for each uninterruptible power supply, a priority selection unit that will be previously the master prioritization in the uninterruptible power supply by this number, according to the inverter in each uninterruptible power supply and information transmission means for transmitting the selection conditions or load powered state and commercial synchronous mode or free-running mode to another uninterruptible power supply, UPS became master Location is When it becomes impossible commercial synchronous mode commercial synchronous operation commercial reference voltage deviates from the or or commercial synchronization tracking range becomes abnormal, in the transmitted by the information transmitting means commercial synchronization can be run in this slave Among the existing uninterruptible power supplies, the one with the higher priority given by the priority selection means becomes the master, performs the output voltage phase control, and the master which cannot perform the commercial synchronous operation is operated as the slave. a selecting means for switching to, the transmitted by the information transmitting means, a master for all the uninterruptible power supply in parallel operation is self operated in free-running mode at a fixed frequency when it becomes impossible to commercial synchronous operation the selecting means for determining to what higher prioritized priority priority selection unit, those having a.

The uninterruptible power supply system according to the present invention is an uninterruptible power supply system in which a plurality of uninterruptible power supply devices equipped with a switching circuit for switching to a commercial power supply without interruption are operated in parallel. The uninterruptible power supply becomes the master and performs reference output voltage phase control, and the remaining uninterruptible power supply performs slave operation that operates to perform phase synchronization with current control by cross current flowing between the uninterruptible power supplies. The uninterruptible power supply which becomes the master according to the priority order among the uninterruptible power supply units set in advance by obtaining the load power supply state by the inverter in each uninterruptible power supply unit and the selection status of commercial synchronous mode or self-running mode A synchronous control selection device that instructs transmission to each uninterruptible power supply so as to select the device and operate the rest as a slave, and according to an instruction from the synchronous control selection device. A synchronization control circuit provided in each uninterruptible power supply that switches between master operation and slave operation is provided, and the above-mentioned synchronous control selection device has a commercial reference voltage that is abnormal when the uninterruptible power supply instructed to the master is in commercial synchronization mode. Alternatively, when commercial synchronous operation becomes impossible due to deviation from the commercial synchronous follow-up range, priority is given according to the priority order of the synchronous control selection device among the uninterruptible power supply devices that were slaves capable of commercial synchronous operation. The higher one becomes the master, performs output voltage phase control, instructs the master that cannot perform commercial synchronous operation to operate as a slave, and all uninterruptible power supply units in parallel operation cannot perform commercial synchronous operation is obtained so as to instruct to those higher priority master that self operated according to the priority order of the synchronous control selection unit in free-running mode at a fixed frequency if

  According to the uninterruptible power supply system of the present invention, a cross current flows between the uninterruptible power supply units in switching between commercial synchronous operation and self-running operation due to a transient state such as a power failure or power recovery of the commercial power source or disturbance of commercial power frequency. And the commercial synchronous operation can be continued even when the commercial synchronous reference voltage of a specific uninterruptible power supply device becomes abnormal, and the reliability of the parallel operation system is improved.

Embodiment 1 FIG.
1 is a circuit configuration diagram showing an uninterruptible power supply system according to Embodiment 1 of the present invention, and shows a case where three uninterruptible power supply apparatuses are operated in parallel. Reference numeral 1 denotes a commercial power source, which is configured to be switched between the generator 2 and the circuit breakers 3 and 4 and is input to the primary of the transformer 5. Here, the circuit breakers 3 and 4 are interlocked so that they are not simultaneously turned on. When the circuit breaker 3 is always turned on and the commercial power source 1 has an abnormality such as a long-term power failure, the circuit breaker 3 is turned off, the circuit breaker 4 is turned on and power is supplied by the generator 2. The system is configured to return to the commercial power source 1 after power recovery. The secondary side of the transformer 5 is input to the uninterruptible power supply devices 7a, 7b and 7c via the circuit breakers 6a, 6b and 6c, and the output of the uninterruptible power supply device is connected to the uninterruptible power supply devices 8a, 8b and 8c. They are connected in parallel and supply power to the load device 9.

Next, the uninterruptible power supply 7a will be described. The converter 10a converts power from alternating current to direct current, and the inverter 12a converts power from direct current to alternating current to output a sine wave voltage. Here, the storage battery 11a is connected to the DC circuit, and the inverter operates so as to supply power from the storage battery 11a to the load when the input power supply is interrupted. Next, in case an abnormality occurs in the inverter 12a, a switch 13a for switching the inverter output and a switching circuit 14a for switching to the commercial power source without interruption are provided so that power supply to the load 9 can be continued. Is done.

  Here, in order to switch to the commercial power supply side without instantaneous interruption, the inverter output must always output a voltage having a phase synchronized with the commercial power supply. Therefore, the commercial power supply voltage is detected by the voltage sensor 60a, and the synchronous reference voltage is detected. This is taken into the synchronous control circuit 61a as Vsa. Further, in order to detect the cross current between the uninterruptible power supply units in parallel operation, the output current of the uninterruptible power supply unit is detected by the current sensor 50a and is taken into the cross current detection circuit 51a, and this is detected as the cross current of other uninterruptible power supply units. In addition to being transmitted to the circuits 51b and 51c, the cross current detection circuits 51b and 51c of the other uninterruptible power supply devices receive other uninterruptible power supply output currents to calculate the cross current Δia and incorporate it into the synchronous control circuit. Yes. The uninterruptible power supply devices 7b and 7c have the same internal configuration and will not be described.

  Next, the operation of the first embodiment will be described. FIG. 2 is a configuration diagram illustrating the synchronization control circuit according to the first embodiment. The commercial frequency is detected by the frequency detection circuit 100 from the commercial reference voltage Vsa detected by the voltage sensor 60a. Next, the selection switch 1 101 selects the commercial synchronization mode that synchronizes with the commercial frequency or the self-running mode that runs at a fixed frequency. Here, the selection switch 1 selects the fixed frequency side (free-running mode) when the commercial reference voltage becomes abnormal due to a power failure or the frequency deviates from the synchronous tracking range as shown in the flowchart of FIG. To work. FIG. 3 is a flowchart for explaining the operation of the selection switch 1 of the synchronous control circuit according to the first embodiment.

  Next, as shown in FIG. 2, the frequency side (commercial synchronous mode side or free-running mode side) selected by the selection switch 1 is used as a master, and the cross current component Δia detected by the cross current detection circuit 51a is converted between The frequency component obtained by the frequency converter 102 that converts the frequency from the cross current generated by the phase deviation is set as a slave, and any one is selected by the selection switch 2 103. Next, the frequency selected by the selection switch 2 is input to the PLL circuit 104, and the output voltage phase of the inverter is obtained. That is, when the master side is selected, frequency synchronization is performed, and when the slave side is selected, operation is performed so as to perform phase synchronization by current control using cross current.

  Here, a method of selecting a master or a slave by the selection switch 2 will be described. FIG. 4 is a flowchart for explaining the operation of the selection switch 2 of the synchronous control circuit according to the first embodiment. The selection switch 2 selects the master operation or the slave operation in the flowchart shown in FIG. Here, each uninterruptible power supply device has a load power supply state by an inverter of another uninterruptible power supply device from another uninterruptible power supply device and a selection state of the commercial synchronous mode or the self-running mode obtained by the selection switch 1. Are interfaced between the synchronous control circuits and communicated with each other. Also, each uninterruptible power supply is assigned a unique device number, the priority order of the devices that perform the master operation is preset, and, for example, as shown in the flowchart of FIG. Each uninterruptible power supply judges independently so that it may operate with priority.

  In other words, if all uninterruptible power supplies are in commercial synchronous mode during parallel operation of 3 units (inverter power supply), select # 1 uninterruptible power supply as the master and select other uninterruptible power supplies to perform slave operation. If # 1 uninterruptible power supply is out of reference voltage and commercial synchronization mode is canceled, select # 2 uninterruptible power supply to perform master operation and other uninterruptible power supply to perform slave operation, When commercial synchronization mode is canceled for both of the # 1 and 2 uninterruptible power supply units, the # 3 uninterruptible power supply unit performs master operation, and the other uninterruptible power supply units are selected to perform slave operation. If the commercial synchronous mode is canceled for all the uninterruptible power supply units, the # 1 uninterruptible power supply unit becomes the master and selects to operate in the self-running mode.

  When one unit is disconnected, two units are operated in parallel (inverter power supply). In this case as well, the uninterruptible power supply unit with the smaller setting number is the same in the uninterruptible power supply unit that can be operated in the commercial synchronous mode. Become a master, perform commercial synchronous operation, and select other uninterruptible power supply units to perform slave operation. Further, if only one unit is operated, the uninterruptible power supply is selected so as to perform the master operation.

As described above, it is possible to suppress cross current from flowing between uninterruptible power supply units when switching between commercial synchronous operation and self-running operation due to a transient state such as a power failure or power recovery of the commercial power source or a disturbance of the commercial power source frequency. In addition, the commercial synchronous operation can be continued even when the commercial synchronous reference voltage of a specific device becomes abnormal, and the reliability of the parallel operation system is improved.
Embodiment 2. FIG.

  FIG. 5 is a circuit configuration diagram showing the uninterruptible power supply system according to the second embodiment, and shows a case of three units in parallel operation. 4 is provided in addition to the uninterruptible power supply device, and the synchronous control of the uninterruptible power supply devices 7a, 7b, and 7c from the synchronous control selection device 70 is provided. By operating the synchronous control circuit of each uninterruptible power supply according to the master / slave selection instruction to the circuits 61a, 61b, 61c, the same effect as in the first embodiment can be obtained. The synchronous control selection device 70 includes the uninterruptible power supply devices 7a, 7b, 7c to the load power supply state by the inverters of the uninterruptible power supply devices 7a, 7b, 7c, and the commercial synchronous mode or the free-running mode obtained by the selection switch 1. The selected state is transmitted.

  Based on the information, if all the uninterruptible power supply units are in commercial synchronous mode, for example, # 1 uninterruptible power supply unit becomes the master, and other uninterruptible power supply units select and instruct to perform slave operation, and # 1 When the uninterruptible power supply is out of reference voltage and commercial synchronization mode is canceled, for example, # 2 uninterruptible power supply performs master operation, and other uninterruptible power supplies select and instruct to perform slave operation. When the commercial synchronization mode is canceled for both the 1 and 2 uninterruptible power supply units, the # 3 uninterruptible power supply unit performs master operation, and the other uninterruptible power supply units select and instruct to perform slave operation. Further, when the commercial synchronization mode is canceled for all the uninterruptible power supply devices, for example, the # 1 uninterruptible power supply device becomes the master and selects and instructs to operate in the self-running mode.

  The synchronous control circuits 61a, 61b, 61c of the uninterruptible power supply devices 7a, 7b, 7c instructed to select from the synchronous control selection device 70 perform master operation or slave operation of the uninterruptible power supply devices 7a, 7b, 7c according to the instructions. The uninterruptible power supply 7a, 7b, 7c is controlled as described above. The priority order between the uninterruptible power supply devices 7a, 7b, and 7c may be set in the synchronous control selection device 70.

  In addition, in embodiment, although 3 units | sets parallel operation was shown, an equivalent effect can be acquired also in 4 units | sets or more. Moreover, although priority selection was made into the one with a small setting number, if each uninterruptible power supply can be distinguished, a priority will be designed suitably. The interface between the synchronization control circuits of each uninterruptible power supply shown in the first embodiment and the interface between the synchronization control selection device 70 and the synchronization control circuit 61 shown in the second embodiment are information transmission means such as a communication circuit. Is appropriately designed.

It is a circuit block diagram which shows the uninterruptible power supply system in Embodiment 1 of this invention. 1 is a configuration diagram illustrating a synchronization control circuit according to a first embodiment. 4 is a flowchart for explaining the operation of the selection switch 1 of the synchronous control circuit according to the first embodiment. 4 is a flowchart for explaining the operation of a selection switch 2 of the synchronous control circuit according to the first embodiment. It is a circuit block diagram which shows the uninterruptible power supply system which is Embodiment 2. FIG. It is a timing chart explaining frequency tracking operation of an uninterruptible power supply.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Generator 3 Circuit breaker 4 Circuit breaker 5 Transformer 6a, 6b, 6c Circuit breaker 7a, 7b, 7c Uninterruptible power supply device 8a, 8b, 8c Circuit breaker 9 Load device 10a, 10b Converter 11a, 11b Storage battery 12a , 12b Inverter 13a, 13b Switch 14a, 14b Switching circuit 50a, 50b Current sensor 51a, 51b Cross current detection circuit 60a, 60b Voltage sensor 61a, 61b Synchronization control circuit 70 Synchronization control selection device 100 Frequency detection circuit 101 Selection switch 1 102 Frequency Converter 103 selection switch 2 104 PLL circuit

Claims (2)

In an uninterruptible power supply system that operates a plurality of uninterruptible power supply units equipped with a switching circuit for switching to commercial power supply without interruption in parallel,
Any one uninterruptible power supply becomes the master and performs reference output voltage phase control, and the slave that operates so that the remaining uninterruptible power supply performs phase synchronization by current control by cross current flowing between the uninterruptible power supplies To drive,
Means for setting an identifiable number for each uninterruptible power supply;
And priority selection means that will be previously the master prioritization in the uninterruptible power supply by this number,
Information transmission means for transmitting the load feeding state by the inverter in each uninterruptible power supply and the selection status of commercial synchronous mode or self-running mode to other uninterruptible power supplies,
If the master uninterruptible power supply is in commercial synchronization mode and the commercial reference voltage becomes abnormal or deviates from the commercial synchronization follow-up range and commercial synchronous operation becomes impossible , the information transmission means transmits the commercial Among the uninterruptible power supplies that were slaves capable of synchronous operation, the one with the higher priority that was prioritized by the priority selection means becomes the master and performs output voltage phase control, making commercial synchronous operation impossible. Selecting means for switching the master to slave operation,
When the uninterruptible power supply units in parallel operation that are transmitted by the information transmission means are unable to perform commercial synchronous operation, the priority selection means selects the master that self-runs in the free-running mode at a fixed frequency. uninterruptible power system comprising selection means attached to the priority order is determined to high, the. In an uninterruptible power supply system that operates a plurality of uninterruptible power supply units equipped with a switching circuit for switching to commercial power supply without interruption in parallel,
Any one uninterruptible power supply becomes the master and performs reference output voltage phase control, and the slave that operates so that the remaining uninterruptible power supply performs phase synchronization by current control by cross current flowing between the uninterruptible power supplies To drive,
Obtains the status of load feeding by the inverter in each uninterruptible power supply and the selection status of commercial synchronous mode or self-running mode, and selects the uninterruptible power supply as the master according to the preset priority order of each uninterruptible power supply And a synchronous control selection device for instructing each uninterruptible power supply to transmit the rest as a slave operation,
A synchronization control circuit provided in each uninterruptible power supply that switches between master operation and slave operation according to an instruction from the synchronization control selection device,
The above-mentioned synchronous control selection device is used for commercial synchronization when the uninterruptible power supply instructed to the master is in commercial synchronous mode and the commercial reference voltage becomes abnormal or the commercial synchronous operation becomes impossible due to deviation from the commercial synchronous tracking range. Among the uninterruptible power supply units that can be operated, the master with the highest priority according to the priority order of the synchronous control selection device becomes the master and performs the output voltage phase control, and the master that cannot perform commercial synchronous operation Instruct the slave to operate,
When all uninterruptible power supplies in parallel operation become unable to perform commercial synchronous operation, the master that self-runs in the self-running mode at a fixed frequency is set to a higher priority according to the priority order of the synchronous control selection device. An uninterruptible power supply system that is instructed.

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