JP7432111B2 - uninterruptible power system - Google Patents

Description

The present invention relates to an uninterruptible power supply system in which a plurality of uninterruptible power supply devices supply power to a common load.

An uninterruptible power supply device is known that includes a converter power supply section, a bypass power supply section, and a switching section that switches between the two power supply sections. Here, the converter power supply unit is a circuit in which a rectifier converts AC power from an input power source into DC power, an inverter converts the DC power into AC power, and supplies the AC power to a load. The bypass power supply unit is a circuit that passes AC power from an input power source and supplies it to a load. In the technology disclosed in Patent Document 1, the power factor of the power supplied to the load is adjusted or the power factor of the power supplied to the load is adjusted by adding the AC power generated by the inverter of the converter power supply section to the output of the bypass power supply section. It operates as an active filter that removes noise from the power generated.

JP2019-9878A

An uninterruptible power supply system is known that includes a plurality of the above-mentioned uninterruptible power supplies and these uninterruptible power supplies supply power to a common load. Control modes in this type of uninterruptible power supply system include master-slave control and multi-master control. In master-slave control, one of the plurality of uninterruptible power supplies serves as a master and the others serve as slaves, and the slaves supply power to the load together with the master under the control of the master. In multi-master control, each of a plurality of uninterruptible power supplies supplies power to a load while being synchronized with each other.

In master-slave control, the master generates and supplies many parameters to the slave, including, for example, control information for the inverter of the converter power supply. Therefore, if a failure occurs in the master, it is necessary to select a new master from among the slaves and have that slave take over the role of master in order to continue power supply. However, it takes time to take over the role of the master. Therefore, in master-slave control, if the master fails, there is a risk that power supply control will be in a suspended state until the master's role is taken over.

With multi-master control, each uninterruptible power supply generates its own parameters for power supply control, so there is no such risk. However, an uninterruptible power supply system that performs multi-master control has a problem in that it is difficult to perform bypass power supply. More specifically, in bypass power supply, the inverter of the converter power supply section generates reactive power and adds it to the output voltage of the bypass power supply section, thereby adjusting the power factor of the power supplied to the load. However, in an uninterruptible power supply system, the characteristics of the bypass power supply parts of each uninterruptible power supply device vary, so when multi-master control is performed, the outputs of the bypass power supply parts become uneven. In addition, in multi-master control, the generation control of reactive power by the inverters of each uninterruptible power supply is uneven, so the output obtained from each uninterruptible power supply becomes unstable. For this reason, an uninterruptible power supply system that has a function of bypass power supply and is capable of multi-master control has not been provided.

The present invention has been made in view of the problems described above, and an object of the present invention is to provide an uninterruptible power supply system that is equipped with a bypass power supply function and is capable of multi-master control.

An uninterruptible power supply system according to the present invention is an uninterruptible power supply system in which a plurality of uninterruptible power supplies supply power to a common load, and each of the plurality of uninterruptible power supplies supplies power based on DC power. a converter power supply unit that generates AC power to be supplied to the load; and a bypass power supply unit that generates AC power to be supplied to the load based on AC power from an input power source, and the bypass power supply unit generates AC power to be supplied to the load from the converter power supply unit. It is possible to switch between a converter power supply mode in which AC power is supplied to the load and a bypass power supply mode in which AC power is supplied from the bypass power supply unit to the load, and in the converter power supply mode, the plurality of uninterruptible power supplies The device performs multi-master control in which power is supplied to the load under the control of each device, and in the bypass power supply mode, the plurality of uninterruptible power supplies are under the control of the master uninterruptible power supply. , the slave uninterruptible power supply performs master-slave control to supply power to the load.

According to this invention, the plurality of uninterruptible power supplies perform power supply in the converter power supply mode under multi-master control, and perform power supply in the bypass power supply mode under master-slave control. Therefore, an uninterruptible power supply system that has a function of bypass power supply and is capable of multi-master control is realized.

1 is a block diagram showing the configuration of an uninterruptible power supply system that is an embodiment of the present invention. FIG. 2 is a circuit diagram showing a configuration example of an inverter and a bypass power supply section of a converter power supply section in the same embodiment. It is a flowchart which shows the flow of the 1st switching process in the same embodiment. It is a flowchart which shows the flow of the 2nd switching process in the same embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of an uninterruptible power supply system according to an embodiment of the present invention. This uninterruptible power supply system includes two uninterruptible power supplies 100_1 and 100_2 that supply power to a common load 202. AC power is supplied to the uninterruptible power supplies 100_1 and 100_2 from an input power source 201 such as a commercial power source. Further, batteries 203_1 and 203_2 are externally attached to the uninterruptible power supplies 100_1 and 100_2, respectively.

In the example shown in FIG. 1, two uninterruptible power supplies 100_1 and 100_2 are provided in the uninterruptible power supply system, but the number of uninterruptible power supplies may be three or more. Uninterruptible power supplies 100_1 and 100_2 have the same configuration. Therefore, hereinafter, both will be collectively referred to as the uninterruptible power supply 100 unless it is necessary to distinguish between them. Furthermore, for convenience of explanation, batteries 203_1 and 203_2 are also collectively referred to as battery 203.

The uninterruptible power supply 100 includes a converter power supply section 110, a bypass power supply section 120, a switching section including switches SW1 to SW4, and a control section 130. Converter power supply unit 110 includes a rectifier 111 , a DC/DC converter 112 such as a chopper, and an inverter 113 . The rectifier 111 is a device that converts AC power supplied from the input power source 201 via the switch SW3 into DC power. The DC/DC converter 112 charges the battery 203 via the switch SW4 with the DC power obtained from the rectifier 121, and also extracts the DC power from the battery 203 and supplies it to the inverter 113. The inverter 113 is a device that generates alternating current power based on the direct current power supplied from the DC/DC converter 112. Bypass power supply unit 120 is a device that generates AC power to be supplied to load 202 based on AC power supplied from input power supply 201 . The control unit 130 is a device that switches ON/OFF of the switches SW1 to SW4 and controls the converter power supply unit 110 and the bypass power supply unit 120.

FIG. 2 is a circuit diagram showing a specific configuration example of the inverter 113 and the bypass power supply section 120 in the converter power supply section 110. FIG. 2 shows a configuration example in which the input power source 201 is a three-phase AC power source and the load 202 also receives three-phase AC power supply. Further, FIG. 2 shows a state in which the switches SW1 and SW2 of FIG. 1 are ON.

The inverter 113 includes an inverter control section 310 and an inverter main circuit 320. DC power extracted by the DC/DC converter 112 in FIG. 1 is applied to the positive power supply terminal P and the negative power supply terminal N of the inverter main circuit 320. The inverter main circuit 320 includes U-phase arms 321 and 324 connected in series between a positive power supply terminal P and a negative power supply terminal N, V-phase arms 322 and 325 connected in series between the same power supply terminals, and the same power supply terminal N. It has W-phase arms 323 and 326 connected in series between terminals. These arms 321 to 326 include semiconductor switching elements such as FETs (Field Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors), and free-wheeling diodes connected in antiparallel to the semiconductor switching elements. including each. The common connection point of arms 321 and 324 is connected to the U-phase AC output terminal TU, the common connection point of arms 322 and 325 is connected to the V-phase AC output terminal TV, and the common connection point of arms 323 and 326 is connected to the W-phase AC output terminal TV. Each is connected to an AC output terminal TW. These AC output terminals TU, TV, and TW are terminals that output three-phase AC power to the load 202. Inverter control section 310 generates pulse width modulated gate signals G1 to G6, respectively, based on control information provided from control section 130. In the inverter main circuit 320, the semiconductor switching elements of the arms 321 to 326 are switched ON/OFF by the gate signals G1 to G6. As a result, AC power is output to the AC output terminals TU, TV, and TW via the arms 321 to 326.

Bypass power supply section 120 has bypass circuits 121, 122, and 123 corresponding to U phase, V phase, and W phase, respectively. Bypass circuit 121 includes thyristors 121F and 121R connected in antiparallel. Similarly, the bypass circuit 122 is made up of thyristors 122F and 122R connected in antiparallel, and the bypass circuit 123 is made up of thyristors 123F and 123R connected in antiparallel. The thyristors 121F, 122F, and 123F are ignited to cause current to flow from the input power supply 201 side to the three-phase AC output terminals TU, TV, and TW. In addition, the thyristors 121R, 122R, and 123R are each fired to cause current to flow from the three-phase AC output terminals TU, TV, and TW to the input power source 201.

The uninterruptible power supply 100 has an operation mode called a constant converter power supply mode, which is a type of converter power supply mode. In this constant converter power supply mode, the control unit 130 turns off the switch SW2 and turns on the switches SW1, SW3, and SW4. In the constant converter power supply mode, the rectifier 121 converts AC power supplied from the input power source 201 into DC power, the DC/DC converter 112 charges the battery 203, and the DC/DC converter 112 operates to charge the battery 203. In parallel, an operation is performed in which DC power is taken out from the inverter 113, converted into AC power by the inverter 113, and supplied to the load 202.

Further, the uninterruptible power supply 100 has an operation mode during a power outage, which is another type of converter power supply mode. During a power outage, switches SW2 and SW3 are turned off, and switches SW1 and SW4 are turned on. In the operation mode during a power outage, the DC/DC converter 112 extracts DC power from the battery 203, the inverter 113 converts it into AC power, and supplies the AC power to the load 202.

Further, the uninterruptible power supply 100 has a bypass power supply mode. In this bypass power supply mode, the control unit 130 turns on the switches SW1 to SW4. In bypass power supply mode, bypass power supply unit 120 passes AC power supplied from input power supply 201 . At this time, the control unit 130 controls the conduction periods of the thyristors 121F to 123F and 121R to 123R of the bypass power supply unit 120 in accordance with fluctuations in the load 202. Furthermore, in the bypass power supply mode, the inverter 113 of the converter power supply unit 110 generates reactive power for adjusting the power factor of the AC power supplied to the load 202 under the control of the control unit 130, and 120 to the AC output terminals TU, TV, and TW. Furthermore, under the control of the control unit 130, the inverter 123 operates as an active filter that reduces noise when noise occurs in the AC power output by the bypass power supply unit 120.

In the uninterruptible power supply system according to this embodiment, power is supplied to a common load 203 by the uninterruptible power supplies 100_1 and 100_2 working together. As described above, there are multi-master control and master-slave control as control modes for coordinating a plurality of uninterruptible power supplies 100. Until now, it has been difficult to perform bypass power supply in uninterruptible power supply systems that perform multi-master control. In the bypass power supply mode, for example, in FIG. 2, the inverter 113 generates reactive power and adds it to the output voltage of the bypass power supply unit 120, thereby adjusting the power factor of the power supplied to the load 202. Here, since there are variations in the characteristics of the bypass power supply units 120 of the uninterruptible power supplies 100_1 and 100_2, each control unit 130 of the uninterruptible power supplies 100_1 and 100_2 independently controls the conduction period of the thyristor of the bypass power supply unit 120. If this is done, the outputs of each bypass power supply section will become uneven. In addition, in multi-master control, the generation control of reactive power by the inverters 113 of the uninterruptible power supplies 100_1 and 100_2 is also uneven, so the output obtained from each uninterruptible power supply 100_1 and 100_2 becomes unstable. .

Therefore, in this embodiment, the plurality of uninterruptible power supplies 100_1 and 100_2 perform master-slave control in the bypass power supply mode. That is, in the bypass power supply mode, one of the uninterruptible power supplies 100_1 and 100_2 becomes a master and the other becomes a slave, and the slave uninterruptible power supply generates AC power under the control of the master uninterruptible power supply. do.

For example, when the uninterruptible power supply 100_1 is the master and the uninterruptible power supply 100_2 is the slave, the control unit 130 of the uninterruptible power supply 100_1, which is the master, controls the AC power from the input power supply 201 and the AC power supplied to the load 202. monitor. Then, the control unit 130 of the master uninterruptible power supply 100_1 determines an appropriate conduction period of the bypass power supply unit 120 based on the state of the load 202, and determines an appropriate conduction period of the bypass power supply unit 120 for only this conduction period. Generate control information. Then, the control unit 130 controls the conduction period of the bypass power supply unit 120 according to this control information, and sends this control information to the control unit 130 of the uninterruptible power supply 100_2, which is the slave. In this way, in the uninterruptible power supplies 100_1 and 100_2, the conduction period of the bypass power supply unit 120 is controlled based on the same control information.

Further, the control unit 130 of the uninterruptible power supply 100_1, which is the master, detects the power factor of the AC power supplied to the load 202, and determines the phase and amplitude of reactive power to be generated in order to adjust this power factor. do. Then, the control unit 130 of the uninterruptible power supply 100_1, which is the master, generates control information for generating the reactive power and supplies it to the inverter 113 and the control unit 130 of the uninterruptible power supply 100_2, which is the slave. As a result, in the uninterruptible power supplies 100_1 and 100_2, the inverter 113 generates reactive power to be added to the output of the bypass power supply unit 120 based on the same control information.

Further, the control unit 130 of the uninterruptible power supply 100_1, which is the master, detects noise generated in the AC power supplied to the load 202, and determines the waveform of the AC power to be generated in order to remove this noise. Then, the control unit 130 of the uninterruptible power supply 100_1, which is the master, generates control information for generating the AC power and supplies it to the inverter 113 and the control unit 130 of the uninterruptible power supply 100_2, which is the slave. As a result, the uninterruptible power supplies 100_1 and 100_2 operate as active filters in which the inverter 113 generates AC power for noise removal based on the same control information.

Further, the plurality of uninterruptible power supplies 100_1 and 100_2 perform multi-master control in which AC power is generated under each control in the converter power supply mode.

Specifically, in the converter power supply mode, each control unit 130 of the uninterruptible power supplies 100_1 and 100_2 detects the phase of AC power from the input power source 201, and outputs the AC power that is phase-synchronized with this AC power without interruption. Each inverter 113 of power supply devices 100_1 and 100_2 is caused to generate the power. At this time, each control unit 130 of the uninterruptible power supplies 100_1 and 100_2 independently detects fluctuations in the load 202, and controls the inverter 113 according to the load fluctuations.

FIG. 3 is a flowchart showing the flow of the first switching process executed in this embodiment. This first switching process is a process of switching from converter power supply mode to bypass power supply mode. This first switching process is executed by each control unit 130 of the uninterruptible power supplies 100_1 and 100_2, for example, when an execution instruction is given by operating an operation unit (not shown).

In the converter power supply mode, multi-master control is performed in the uninterruptible power supplies 100_1 and 100_2. When execution of the first switching process is instructed by operation of an operation unit (not shown), each control unit 130 of the uninterruptible power supply 100_1 and 100_2 starts bypass power supply by full ignition to each bypass power supply unit 120. (Step Sa1). That is, the full firing causes each of the thyristors 121F to 123F and 121R and 123R of the bypass power supply unit 120 to function as a diode.

Next, the control units 130 of the uninterruptible power supplies 100_1 and 100_2 determine which one of them is to be the master by communicating with each other (step Sa2). In this case, for example, the unit with the lowest unit number among the plurality of uninterruptible power supplies in operation may be set as the master.

Next, the master uninterruptible power supply sends a command to start control to the slave uninterruptible power supply, and the slave uninterruptible power supply returns approval of the command to the master uninterruptible power supply. do. As a result, a link between the master and slave is established (step Sa3).

Next, each control unit 130 of the uninterruptible power supplies 100_1 and 100_2 starts bypass power supply by master-slave control (step Sa4). The above is the flow of the first switching process.

FIG. 4 is a flowchart showing the flow of the second switching process executed in this embodiment. This second switching process is a switching process from the bypass power supply mode to the converter power supply mode. Like the first switching process, this second switching process is also executed by each control unit 130 of the uninterruptible power supplies 100_1 and 100_2, for example, when an execution instruction is given by operating an operation unit (not shown).

In the bypass power supply mode, master-slave control is performed in the uninterruptible power supplies 100_1 and 100_2. When execution of the second switching process is instructed by operation of an operation unit (not shown), each control unit 130 of the uninterruptible power supply 100_1 and 100_2 starts bypass power supply by full ignition to each bypass power supply unit 120. (Step Sb1). That is, the full firing causes each of the thyristors 121F to 123F and 121R and 123R of the bypass power supply unit 120 to function as a diode.

Next, each control unit 130 of the uninterruptible power supplies 100_1 and 100_2 stops power supply control by each inverter 113 (step Sb2). Here, power supply control by the inverter 113 means generation of reactive power for adjusting the power factor of the AC power supplied to the load 202 and operation as an active filter for removing noise.

Next, each control unit 130 of the uninterruptible power supplies 100_1 and 100_2 terminates the master-slave relationship (step Sb3). Specifically, a command to end master-slave control is sent from the control unit 130 of the master uninterruptible power supply to the control unit 130 of the slave uninterruptible power supply.

Next, each control unit 130 of the uninterruptible power supplies 100_1 and 100_2 starts converter power supply by multi-master control (step Sb4). That is, each control unit 130 causes each inverter 113 to generate AC power that is phase-synchronized with the AC power from the input power source 201.

Next, each control unit 130 of the uninterruptible power supplies 100_1 and 100_2 turns off the switch SW2 to stop the bypass power supply by the bypass power supply unit 120 (step Sb5). The above is the flow of the second switching process.

As described above, in this embodiment, the plurality of uninterruptible power supplies 100_1 and 100_2 perform power supply in converter power supply mode under multi-master control, and perform power supply in bypass power supply mode under master-slave control. Therefore, an uninterruptible power supply system that has a function of bypass power supply and is capable of multi-master control is realized. Further, in this embodiment, in the process of switching from one of the converter power supply mode and the bypass power supply mode to the other, the bypass power supply unit is fully turned on, and each thyristor functions as a diode to perform bypass power supply. Therefore, the power supply mode can be switched without causing an instantaneous interruption of power supply to the load 202.

<Other embodiments>
Although one embodiment of this invention has been described above, other embodiments of this invention are possible. For example:

(1) In the above embodiment, the batteries 203_1 and 203_2 are attached externally to the uninterruptible power supplies 100_1 and 100_2, but they may be built-in batteries in each uninterruptible power supply.

(2) In multi-master control, the control units 130 of the plurality of uninterruptible power supplies caused each inverter 113 to generate AC power that was phase-synchronized with the AC power from the input power source 201. However, instead of doing so, one of the plurality of uninterruptible power supplies generates phase information indicating the phase of the AC power from the input power supply 201 (for example, information indicating the zero-crossing timing of the AC voltage). However, the inverter 113 of each uninterruptible power supply may generate AC power in phase synchronization with this phase information.

100_1, 100_2...Uninterruptible power supply, 201...Input power supply, 202...Load, 203_1, 203_2...Battery, SW1 to SW4...Switch, 110...Converter power supply section, 120...Bypass power supply section, 111... Rectifier, 112... DC/DC converter, 113... Inverter, 130... Control unit, 310... Inverter control unit, 320... Inverter main circuit, 321-326... Arm, P, N... Power supply terminal, TU, TV, TW... AC output terminal, 121, 122, 123... Bypass circuit, 121F to 123F, 121R to 123R... Thyristor.

Claims (5)

An uninterruptible power supply system in which multiple uninterruptible power supplies supply power to a common load,
Each of the plurality of uninterruptible power supplies is
a converter power supply unit that generates AC power to be supplied to a load based on DC power;
a bypass power supply unit that generates AC power to be supplied to the load based on AC power from an input power source,
It is possible to switch between a converter power supply mode in which AC power is supplied from the converter power supply unit to the load, and a bypass power supply mode in which AC power is supplied to the load from the bypass power supply unit,
In the converter power supply mode, the plurality of uninterruptible power supplies perform multi-master control to supply power to the load under the control of each uninterruptible power supply,
In the bypass power supply mode, the plurality of uninterruptible power supplies perform master-slave control in which the slave uninterruptible power supply supplies power to the load under the control of the master uninterruptible power supply.
Uninterruptible power system. 2. In the bypass power supply mode, the converter power supply units of the plurality of uninterruptible power supplies generate reactive power for adjusting the power factor of the AC power supplied to the load. Uninterruptible power supply system described in. In the bypass power supply mode, the converter power supply units of the plurality of uninterruptible power supplies function as an active filter that removes noise generated in the AC power supplied to the load. 2. The uninterruptible power supply system described in 2. In the converter power supply mode, the converter power supply units of the plurality of uninterruptible power supplies generate AC power that is phase-synchronized with the AC power supplied from the input power source. The uninterruptible power supply system according to any one of the above. The bypass power supply includes a pair of thyristors connected in anti-parallel between the input power source and the load,
Any one of claims 1 to 4, wherein in the process of switching from one of the converter power supply mode and the bypass power supply mode to the other, bypass power supply is performed by causing each thyristor of the bypass power supply unit to function as a diode. The uninterruptible power supply system described in item 1.

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