JP4340668B2 - Disaster response distributed power supply system and operation method of power conditioner - Google Patents

Description

  The present invention relates to a distributed power supply system for disasters that can connect a distributed power source such as a solar cell or a fuel cell to a system power source, and can operate the distributed power source independently to supply power to a three-phase power load in the event of a power failure of the system power source. And an operation method of a power conditioner in such a distributed power supply system for disasters.

  In recent years, solar cells, fuel cells, wind power generators, etc. have been deployed as distributed power supply devices at the location of power consumers (customers), and the power from these distributed power sources and the grid power supply (commercial power supply) of electric power companies A distributed power supply system that is combined with other power sources to cover the power consumption of power consumers is attracting attention.

  In order to superimpose the power from the distributed power source on the AC power from the system power source and distribute it to the load in the home of the power consumer, it is necessary to link the distributed power source to the system power source. The power from the distributed power source is often direct current power, and even if it is alternating current power, the frequency and voltage are not compatible with the system power source, so it is converted into predetermined alternating current power from the distributed power source, A power conditioner (PCS) that adapts the frequency and voltage to the power from the system power supply is used. The output line of AC power from the inverter is generally connected to the distribution line from the system power supply side in the distribution board provided in the home of the power consumer, and this allows the load to be placed in the home of the power consumer. On the other hand, AC power from the distributed power source and AC power from the system power source are supplied together. Since the power conditioner outputs AC power linked to the system power supply, an inverter is provided at the output portion. In this case, the frequency, phase and voltage of the AC power supplied to the load are given from the system power supply side, and in order to supply the power from the distributed power supply to the load to the maximum, the inverter is a current control system. Is used.

  By the way, from the viewpoint of power transmission efficiency, the power grid of electric power companies generally requires single-phase AC power by transmitting three-phase AC power from a three-phase generator to a consumption area via a transmission line or substation. In such a case, the three-phase power is converted into single-phase power at a position immediately before the place where the single-phase AC power is consumed. Therefore, the unit price of electric power is higher for single-phase power than for three-phase power, and when using a distributed power supply linked to the system power supply, use it on the single-phase power side rather than on the three-phase power side. The cost merit becomes larger. Therefore, at present, as a power conditioner for connecting a distributed power supply to a system power supply, one that outputs single-phase AC power is generally used.

  By the way, since distributed power sources such as solar cells and fuel cells can supply power independently, emergency power sources in the event that a disaster such as an earthquake occurs and power outages in the system power source are expected to continue As promising. However, at present, a system that connects a distributed power source to a system power supply generally outputs a single-phase AC power, so it can be used for the purpose of supplying three-phase AC power to a load in the event of a system power failure. Can not. On the other hand, there is a demand for driving a load driven by three-phase AC power, that is, a three-phase load, when the system power supply fails. For example, in a fuel supply station (gas station) that supplies fuel such as gasoline and light oil to road transport vehicles such as trucks, buses, and passenger cars, it is driven by a three-phase motor to transfer the fuel from the fuel tank to the vehicle. The pump is used. Since it is necessary to refuel various types of emergency vehicles even during disasters such as earthquakes, the fuel supply station normally uses the power from the distributed power source as a load driven by single-phase AC power, that is, a single-phase load. Even if the power is supplied, it is desirable that the three-phase AC power can be generated by the power from the distributed power source and supplied to the three-phase load at the time of power failure of the system power source.

  In addition, in patent 3289418 specification (patent document 1), when the emergency private power generation equipment of three-phase alternating current power is equipped etc., three-phase alternating current power is changed into single-phase alternating current power at the time of a power failure of a system power supply. A configuration for converting and supplying to a load is disclosed. However, in this configuration, three-phase AC power can be obtained even in an emergency, and then single-phase AC power is generated. Three-phase AC power is typically generated from a distributed power source that outputs DC power, such as a solar cell or a fuel cell. Cannot be used when generating phase AC power.

Japanese Patent No. 3553180 (Patent Document 2) discloses a configuration in which three-phase AC power is generated from a DC power source. However, since this configuration does not generate single-phase AC power, it is normally used to generate single-phase AC power linked to the system power supply and to generate three-phase AC power when the system power supply fails. I can't.
Japanese Patent No. 3289418 Japanese Patent No. 3553180

  As described above, distributed power sources such as solar cells and fuel cells are deployed at the location of power consumers, and these distributed power sources are connected to the system power source to provide single-phase AC for the loads in the homes of the power consumers. Although a power supply system for supplying power has been put into practical use, it is not possible to obtain a three-phase AC power from the power supply system by operating a distributed power supply in the event of a grid connection power outage.

  Accordingly, an object of the present invention is to provide a disaster in which single-phase AC power can be output by connecting a distributed power supply to a system power supply during normal times, and three-phase AC power can be supplied by power from the distributed power supply during a power failure of the system power supply. It is an object to provide a time-dependent distributed power supply system and a method of operating a power conditioner in such a disaster-ready distributed power supply system.

  The disaster-response distributed power supply system of the present invention is a disaster-response distributed power supply system that is connected to a system power supply. A plurality of power supplies that can connect a distributed power supply and a distributed power supply to a system power supply and output single-phase AC power. When connecting to the grid power supply, connect multiple power conditioners in parallel to each other and connect to the grid power supply. When the grid power supply fails, multiple power conditioners are connected to the grid power supply. Three-phase AC power can be obtained by disconnecting the conditioners and operating the plurality of power conditioners so that a predetermined phase difference (specifically 120 °) occurs between the AC outputs of the plurality of power conditioners. It is characterized by doing so.

  The disaster-response distributed power supply system of the present invention typically has three power conditioners, and when three-phase AC power is obtained, the outputs of the three power conditioners are connected by Y connection or Δ connection. Is. Alternatively, two power conditioners are provided, and when three-phase AC power is obtained, the outputs of the two power conditioners are connected by V connection.

  In the disaster response distributed power supply system of the present invention, the rated output of each power conditioner is 0.1 kW or more and 100 kW or less, preferably 0.3 kW or more and 50 kW or less, more preferably 1 kW or more and 10 kW or less. . When the output of the power conditioner is too small, it becomes difficult to make the output voltage of the power conditioner sufficiently high, which may hinder the connection to the system power supply. On the other hand, when the rated output of the power conditioner is too large, a special element is required as a power semiconductor element that constitutes the inverter circuit of the power conditioner, and versatility is impaired.

  In the disaster response distributed power supply system of the present invention, in order to output three-phase AC power, one of the plurality of power conditioners serves as a master and serves as a reference for each phase of the three-phase AC power. Preferably, the signal is generated and transmitted to another inverter.

  The disaster-response distributed power supply system of the present invention is provided, for example, in a fuel supply station (gasoline station or the like) that supplies fuel. In this case, the three-phase AC power is supplied to a three-phase motor that drives a fuel pump that transfers fuel.

  The operation method of the power conditioner of the present invention is the operation method of a plurality of power conditioners that link the distributed power source to the system power source. When the power source is linked to the system power source, the outputs of the plurality of power conditioners are connected in parallel. Connect to the grid power supply, operate multiple power conditioners in the current control mode, and disconnect them from the grid power supply when not connecting to the grid power supply. A plurality of power conditioners are operated in the voltage control mode so that a predetermined phase difference (specifically 120 °) occurs between the AC outputs of the conditioners and the AC output corresponds to each phase of the three-phase AC. It is characterized by that.

  As power conditioners for distributed power supplies, single-phase output power conditioners for homes and small stores are widely used. The diversion of these for industrial use is effective from the viewpoint of widespread use, and the output single-phase AC power can be used for lighting and air conditioning. However, conventionally, as long as a single-phase power conditioner is used, there is a problem in that highly important three-phase AC power for power cannot be obtained during a power failure. The present invention obtains three-phase AC power by combining a plurality of single-phase power conditioners, changing the connection in the event of an emergency such as a power failure, and operating these power conditioners with a phase shift of 120 °. Has the special effect of being able to.

  In particular, the gas station is required to have no problem with the refueling function even in the event of a power failure such as a disaster, but since the refueling pump operates with three-phase AC power, the distributed power supply system for disasters according to the present invention Installation is effective.

  Next, a preferred embodiment of the present invention will be described with reference to the drawings. The distributed power system for disasters according to the present invention uses two or more power conditioners that each output single-phase AC power (in the embodiment described below, three power conditioners are used), and the system power supply is When it is functioning normally, the output of these two or more inverters is connected in parallel to the system power supply, connected to the system power supply to supply single-phase AC power to the load, and the system power supply fails. In such a case, disconnect these power conditioners from the system power supply, change the connection between the outputs of the power conditioners, and then change the connection between the phases of the single-phase AC power output by each of these power conditioners. A three-phase AC power can be supplied to a three-phase load such as a motor so that a phase difference (specifically 120 °) is generated.

  FIG. 1 shows the configuration of a disaster-response distributed power supply system according to an embodiment of the present invention. In FIG. 1, (A) shows the connection when the system power supply is operating normally, and (B) shows the connection when the system power supply is out of power. Actually, the connection of (A) is normally performed, and when the system power supply is interrupted, the connection is manually switched to (B) as described later.

  As distributed power supplies, there are provided DC power supplies 11 to 13 such as solar cells, and power conditioners (PCS) 21 to 23 that are supplied with DC power from the DC power supplies 11 to 13 and output single-phase AC power, respectively. In addition, single-phase AC power and three-phase AC power are supplied from the system power supply. Three-phase AC power is supplied to a three-phase load 51 such as a motor via a three-phase distribution board 41. At normal times, as shown in FIG. 1A, a three-phase distribution board 41 and a three-phase load 51 are directly connected. The single-phase AC power is supplied to a single-phase load 52 such as lighting through a single-phase distribution board 42. In this example, the connection between the single-phase distribution board 42 and the single-phase load 52 is fixed. In addition to these distribution boards 41 and 42, there is provided a three-phase distribution board 44 dedicated for power failure that is used when the system power supply is interrupted. When the system power supply is operating normally, the power supply and the load are not connected to the three-phase distribution board 44 dedicated for power failure.

  Normally, as shown in FIG. 1A, the outputs of the power conditioners 21 to 23 are connected in parallel to each other and supplied to the single-phase distribution board 42 via the circuit breaker 43. Yes. The circuit breaker 43 is provided in order to disconnect the power conditioners 21 to 23 from the system power supply when the system power supply fails. Therefore, at this time, the DC power from the DC power supplies 11 to 13 is converted into single-phase AC power by the power conditioners 21 to 23, and the single power from the system power supply is supplied to the load 52 via the distribution board 42. Single-phase AC power from the phase AC power and the power conditioners 21 to 23 is supplied. As described above, the inverter circuits in the power conditioners 21 to 23 are driven in the current control mode in which the output current value is controlled to be the target value.

  When the system power supply is interrupted while the power conditioners 21 to 23 are connected to the system power supply, the AC power output from the power conditioners 21 to 23 flows out to the distribution network on the system power supply side, and the power failure occurs. Therefore, the distribution line and distribution network on the system power supply side that should not have been originally charged will be charged by the distributed power supply, causing electric shock accidents during work such as power failure recovery, and the phase on the system power supply side when the system is restored May cause a failure due to a phase mismatch between the distribution line and the distribution line, and makes it difficult to search for a failure occurrence position. Therefore, when the power conditioner detects that the power supply from the system power supply has been cut off, the power conditioner immediately stops the operation of the power conditioner, and if necessary, removes the power conditioner itself from the distribution line. It is configured to be disconnected by a switch or circuit breaker. Here, out of the power conditioners 21 to 23 connected in parallel, the power conditioner 21 is used as a master power conditioner, and the power conditioner 21 detects a power failure of the system power supply. The power conditioners 22 and 23 are notified of the detection of a power failure, the operation of each of the power conditioners 21 to 23 is stopped, and the circuit breaker 43 is set in a disconnected state. Alternatively, the power conditioners 21 to 23 may communicate with each other to detect a power failure of the system power supply.

  Next, a configuration for supplying three-phase AC power to the three-phase load 51 when the system power supply is interrupted will be described with reference to FIG.

  When the system power supply is out of power, the power conditioners 21 to 23 are manually disconnected from the circuit breaker 43, and the three-phase load 51 is removed from the three-phase distribution board 41. Then, the three distribution lines to the three-phase load 51 and the single-phase AC outputs of the three power conditioners 21 to 23 are connected to each other via the three-phase distribution board 44 dedicated for power failure. Then, the three power conditioners 21 to 23 are operated so that the phases of the AC output are shifted from each other by 120 °. As a result, three-phase AC power is supplied to the three-phase load 51, and the three-phase load 51 can be used. When the three-phase load 51 is a three-phase motor that drives the fuel pump in the fuel supply station, the emergency vehicle or the like can be refueled even during a power failure of the system power supply.

  Next, the configuration of the power conditioner for connecting the three power conditioners 21 to 23 in this way so that three-phase AC power can be generated will be described. Since the power conditioner outputs single-phase AC power as a single unit, in order to obtain three-phase AC power by combining these three units, the phases of the AC power output by the power conditioner are mutually It is necessary to shift by 120 °. Therefore, in the present embodiment, the master power conditioner 21 generates a synchronization signal (period trigger) indicating a reference frequency and phase difference, and transmits these synchronization signals to the slave power conditioners 22 and 23. In the slave power conditioner 22.23, three-phase AC power is normally generated by generating and outputting AC power in synchronization with the synchronization signal. Further, a standby signal and an operation stop signal are exchanged between the master and slave power conditioners, as will be described later.

  FIG. 2 is a block diagram showing the configuration of such a power conditioner. Although there are differences between the master and the slave, the configurations of the power conditioners 21 to 23 are the same. That is, the power conditioners 21 to 23 receive DC power from the DC power supplies 11 to 13 and boost the DC power to an appropriate voltage, and an inverter circuit that converts the boosted DC power into single-phase AC power. 32, a gate drive signal generator 33 for generating a gate drive signal for driving the gate of the power semiconductor element in the inverter circuit 32, a sensor 34 for measuring the output current / output voltage of the inverter circuit 32, and a sensor 34 A target value calculation unit 35 for calculating a target value for controlling the gate of the power semiconductor element in the inverter circuit 32 based on the waveform observation value at, and a target voltage for generating a target waveform in the output voltage waveform of the inverter circuit 32 A waveform generator 36.

  Since the inverter circuit 32 is supposed to operate in the current control mode when connected to the system power supply, the target value calculator 35 determines the target value based on the current waveform observed by the sensor 34. The target value is sent to the gate drive signal generator 33, and as a result, the inverter circuit 32 is driven and controlled based on the current waveform.

  On the other hand, when the system power supply is at a power failure and is connected as shown in FIG. 1B, the inverter circuit 32 is operated in the voltage control mode. At this time, since the reference frequency and phase are not supplied from the outside, the target voltage waveform generation unit 36 of the master power conditioner 21 outputs a sine wave of a predetermined voltage at a predetermined frequency (50 Hz or 60 Hz). In this way, the target waveform of the output voltage waveform is determined and supplied to the target value calculation unit 25 of the master power conditioner 21, and the slave power conditioners 22 and 23 are used as a reference of frequency and phase. A periodic trigger (synchronization signal) is transmitted. In the period trigger, a predetermined phase difference is provided for each of the slave power conditioners 22 and 23. In the slave power conditioners 22, 23, the target voltage waveform generator 36 receives this periodic trigger, determines the target waveform of the output voltage waveform in the own power conditioner based on the periodic trigger, and outputs it to the target value calculator 35. To do. In both the master and slave power conditioners 21 to 23, the target value calculation unit 35 determines a target value based on the supplied target waveform and the voltage waveform observed by the sensor 34, and gates the target value. As a result, the drive of the inverter circuit 32 is controlled based on the voltage waveform. As a result, AC power whose phase is shifted by 120 ° is output from each of the power conditioners 21 to 23.

  Next, a method for connecting the outputs of the power conditioners 21 to 23 for obtaining three-phase AC power will be described with reference to FIG. FIG. 3A shows an example of Y connection. One of the single-phase AC outputs of each of the power conditioners 21 to 23 is a line of each phase in the Y connection, and the other of the single-phase AC outputs is commonly connected to a ground point (neutral point). FIG. 3B shows an example of Δ connection. Each pair of outputs of each of the power conditioners 21 to 23 is connected in a ring shape so as to be connected to the output of the other power conditioner. Yes. Furthermore, in the present invention, by using the V connection as shown in FIG. 3C, the three-phase AC power can be supplied to the three-phase load 51 using only the two power conditioners 21 and 22. it can. In this case, one output of the power conditioner 21 is connected to the first phase of the three-phase AC, the other output of the power conditioner 21 is connected to one output of the power conditioner 22, and the second phase of the three-phase AC. The other output of the power conditioner 22 is the third phase of the three-phase alternating current.

  Next, a procedure for enabling electric power to be supplied to the three-phase AC load when the system power supply fails will be described with reference to FIG.

  When the system power supply is stopped (step 101), if the circuit breaker 43 is not in the shut-off state, the circuit breaker is set in the shut-off state, and then the connection as shown in FIG. The connection is switched to the connection shown in 1 (B) (step 102). Next, the operation mode is changed from the normal single-phase operation mode in which current control is performed to the three-phase operation mode in which voltage control is performed, and each of the power conditioners 21 to 23 is activated (step 103). At the start of the operation, a periodic trigger serving as a reference for the three-phase operation is transmitted from the master power conditioner 21 to the slave power conditioners 22 and 23 (step 104) to prepare for operation. When the slave power conditioners 22 and 23 are ready for operation, the slave power conditioners 22 and 23 shift to the operation standby state and transmit a standby signal indicating that the operation preparation is completed to the master power conditioner 21. When the standby signal is received from both the slave power conditioners 22 and 23, the master power conditioner 21 starts operation (step 105), and the slave power conditioners 22 and 23 follow the master power conditioner 21. Then, the operation is started (step 107). As a result, three-phase AC power can be supplied to the three-phase load 51.

  Next, the procedure when the system power supply is restored and reconnected to the system when the three-phase AC power is supplied as described above will be described with reference to FIG.

  In order to reconnect to the system, it is necessary to switch the power conditioners 21 to 23 from the three-phase operation to the single-phase operation. Therefore, when it is confirmed that the system power supply has been restored, the three-phase operation mode of the power conditioners 21 to 23 is turned off (step 111). As a result, an operation stop signal is transmitted from the master power conditioner 21 to the slave power conditioners 22 and 23 (step 112), and in response to this, the slave power conditioners 22 and 23 stop operating ( Step 113) Next, the master inverter 21 stops operation (Step 114). Thereafter, the operation mode of the inverters 21 to 23 is switched to the single-phase mode (step 115), and then manually switched from the connection in FIG. 1B to the connection in FIG. 1A (step 116). ). Thereafter, when the circuit breaker 43 is turned on, each of the power conditioners 21 to 23 starts an operation linked to the system power supply (step 117).

  As described above, the distributed power supply system for disaster according to this embodiment can connect the DC power supplies 11 to 13 to the system power supply (single-phase AC power) when the system power supply is operating, When a power failure occurs, three-phase AC power having a high degree of importance can be generated for power by following the procedure described above.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the structure of the disaster-response distributed power supply system of one Embodiment of this invention, Comprising: (A) shows the connection at the time of normal operation, (B) shows the connection at the time of a power failure of a system power supply Yes. It is a block diagram which shows the structure of the power conditioner in the disaster-response distributed power supply system shown in FIG. It is a figure which shows the connection between power conditioners in a three-phase operation mode, (A) shows Y connection, (B) shows Δ connection, and (C) shows V connection. It is a flowchart which shows operation | movement of the disaster-response distributed power supply system shown in FIG. 1, Comprising: (A) shows the process at the time of starting a three-phase operation mode by the power failure of a system power supply, (B) is system power supply The processing when restarting the interconnection operation due to the return of is shown.

Explanation of symbols

11 to 13 DC power supply 21 to 23 Power conditioner 31 DC booster 32 Inverter circuit 33 Gate drive signal generator 34 Sensor 35 Target value calculator 36 Target voltage waveform generator 41 Three-phase distribution board 42 Single-phase distribution board 43 Circuit breaker 44 Three-phase distribution board dedicated for power failure 51 Three-phase load 52 Single-phase load

Claims (7)

In a distributed power system for disasters linked to the grid power supply,
Distributed power supply,
A plurality of power conditioners that can link the distributed power source to a system power source and output single-phase AC power;
With
When interconnecting to the system power supply, the plurality of power conditioners are connected in parallel to each other and connected to the system power supply, and in the event of a power failure of the system power supply, the plurality of power conditioners are disconnected from the system power supply. A three-phase AC power can be obtained by operating the plurality of power conditioners so that a predetermined phase difference is generated between the AC outputs of the plurality of power conditioners. Distributed power system for time.   The distributed power supply system for disasters according to claim 1, comprising three power conditioners and connecting outputs of the three power conditioners by Y connection or Δ connection when obtaining three-phase AC power.   The distributed power supply system for disasters according to claim 1, comprising two power conditioners and connecting the outputs of the two power conditioners by V connection when obtaining three-phase AC power.   The distributed power system corresponding to a disaster according to any one of claims 1 to 3, wherein a rated output of each power conditioner is 0.1 kW or more and 100 kW or less.   Any one of the plurality of power conditioners serves as a master, generates a signal serving as a reference for each phase of the three-phase AC power, and transmits the signal to another power conditioner. 2. A distributed power supply system for disasters according to claim 1.   The disaster according to any one of claims 1 to 5, wherein the disaster is provided in a fuel supply station that supplies fuel, and the three-phase AC power is supplied to a three-phase motor that drives a fuel pump that transfers the fuel. Distributed power system for time. In the operation method of multiple inverters that connect the distributed power supply to the system power supply,
When connecting to the system power supply, the outputs of the plurality of power conditioners are connected in parallel and connected to the system power supply, and the plurality of power conditioners are operated in a current control mode,
When not connecting to the system power supply, the outputs of the plurality of power conditioners are disconnected from the system power supply, and a predetermined phase difference occurs between the AC outputs of the plurality of power conditioners, so that the AC output is A method of operating a power conditioner, wherein the plurality of power conditioners are operated in a voltage control mode so as to correspond to each phase of a three-phase alternating current.

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