JP6536056B2 - Distributed power supply - Google Patents

Description

  The present invention relates to a distributed power supply.

  A distributed power supply including a power generation system is grid-connected to a commercial power supply, and supplies power to, for example, a household power load together with the commercial power supply. Such grid interconnection can use the power of the distributed power supply instead of the power of the commercial power supply, and as a result, the power consumption of the commercial power supply can be reduced.

  When the power generation device of the distributed power supply device generates direct current, the distributed power supply device includes a grid-connected device (power conditioner) having a boost converter and an inverter. In this case, the direct current generated by the power generation apparatus is boosted by the boost converter, and the direct current boosted by the boost converter is converted by the inverter into alternating current synchronized with the alternating current of the commercial power supply. Then, the power generated on the output side of the inverter is supplied (connected) to the commercial power source.

  Also, in recent years, in order to make it possible to use a distributed power supply as a backup power supply at the time of a power failure of a commercial power supply, a distributed power supply apparatus having a stand-alone power supply device capable of supplying power independently of the commercial power supply is also proposed. It is done. For example, Patent Document 1 discloses a cogeneration system as a distributed power supply device including a stand-alone power supply device. The self-supporting power supply device provided in the cogeneration system has a self-supporting connection path and a self-supporting dedicated outlet. One end of the connection path for self-supporting connection is connected in the middle of the connection path for connection which connects the output side of the inverter provided in the grid connection device and the commercial power supply. The stand-alone socket is connected to the other end of the stand-alone connection. At the time of non-power failure, the output side of the inverter is connected to the commercial power supply through the interconnection connection. On the other hand, at the time of a power failure, the output side of the inverter is connected to the independent power supply device. Therefore, power can be supplied to the power load from the stand-alone power outlet of the stand-alone power supply device at the time of a power failure.

JP, 2013-243872, A

  When the power supply system of the distributed power supply apparatus is a single-phase three-wire system, an alternating current of 200 V AC is usually supplied. Therefore, the voltage on the output side of the inverter of the grid interconnection device is also adjusted to AC 200V. In addition, when the distributed power supply has a stand-alone power supply, it is highly likely that an important power load in the home, such as a refrigerator, will be connected to the stand-alone power supply when the commercial power fails. The driving voltage of an important power load in a home is often 100 V AC. Therefore, as for the voltage of the alternating current output from a stand-alone power supply apparatus, it is desirable that it is AC100V.

  That is, it is preferable that the distributed power supply apparatus having the independent power supply apparatus be configured such that AC 200 V AC is output at the time of a power failure and AC 100 V AC is output at the time of a power failure. However, in order to configure as described above, the distributed power supply apparatus is configured such that the AC voltage output from the stand-alone power supply device is smaller than the AC voltage output from the side connected to the commercial power supply. I have to design.

  In order to make the output voltage of the stand-alone power supply device smaller than the output voltage of the side connected to the commercial power supply, the output voltage of the inverter provided in the grid interconnection device is in each of the power failure and non-power failure cases. , And may be adjusted separately. However, in this case, at the time of a power failure, there arises a problem that the output itself is lowered along with the drop of the output voltage of the inverter. For example, when the upper limit (interconnected output) of the alternating current output obtained on the side connected to the commercial power supply at the time of non-power failure is 700 W (AC 200 V, 3.5 A), the alternating current obtained by the independent power supply device at the time of power failure The upper limit (stand-alone output) of the output of is set to 350 W (AC 100 V, 3.5 A) by voltage adjustment by the inverter. That is, at the time of a power failure, only half the power at the time of non-power failure can be obtained.

  In order to solve this, a transformer (transformer) may be provided in the stand-alone power supply device, and means may be employed to step down the output voltage of the inverter with the transformer. According to this, theoretically, even at the time of a power failure, it is possible to obtain an alternating current of AC 100 V with the stand-alone power supply device while maintaining the power (output). However, when the transformer is provided, the conversion efficiency of the transformer is not 100%, which causes a problem that the output is reduced. Therefore, even when the transformer is provided, the output (independent output) obtained at the time of the power failure is smaller than the output (interconnected output) obtained at the time of the non-power failure. If the output obtained at the time of a power failure can not be obtained at the time of a power failure, it may happen that the power load used at the time of a power failure can not be used at the time of a power failure. The occurrence of such a failure leads to the deterioration of the marketability of the distributed power supply.

  An object of the present invention is to provide a distributed power supply having a self-supporting output as high as that of a grid-connected output, and hence a high commercial value.

(Means to solve the problem)
The present invention outputs from a commercial power source (C) a power generation device (2) for generating direct current, a boost converter (6) for boosting a direct current voltage generated by the power generation device, and a direct current boosted by the boost converter. And an interconnection (11) for connecting the output side of the inverter to a commercial power supply, and an interconnection for interconnection that intervenes in the interconnection for interconnection. The grid connection device (3) having the connection switching device (8) for interrupting or connecting, and the primary side is connected to a portion of the connection connection path between the inverter and the connection switching device The output voltage of the inverter is stepped down, and on the secondary side thereof, a transformer (12) for outputting the stepped-down alternating current, a stand-alone connection path (15) connected to the transformer secondary side, and a stand-alone connection A stand-alone power supply unit (14) connected to the A stand-alone power supply device (4) having a stand-alone switching device (13) for blocking or connecting the for-use connection path, and a connection path for interconnection when the commercial power is not working And a switching control unit (16) for controlling the switching device for grid connection and the switching device for self-supporting so that the grid connection path is cut off and the self-supporting connection path is connected when the commercial power source fails. The boost converter is controlled such that the upper limit of the output current of the power generation apparatus is limited to the first upper limit current during power failure, and the upper limit of the output current of the power generation apparatus is higher than the first upper current limit during power failure Boost converter control unit (17) that controls the boost converter to be limited to the current value, and controls the inverter so that the upper limit of the output of the inverter is limited to the first upper limit output value during power failure , The output of the inverter Includes inverter control unit for controlling the inverter so the upper limit is limited high second upper output value than the first upper limit output value (18), a voltage sensor for detecting a voltage value of the transformer secondary, the , the inverter control unit, in the event of a power failure, based on the voltage value detected by the voltage sensor, that Yusuke correcting unit for correcting the output of the inverter to (18a), to provide a distributed power supply. In this case, the correction unit may correct the output of the inverter so that the voltage value on the secondary side of the transformer matches a predetermined voltage value (for example, AC 100 V) at the time of a power failure.

According to the present invention, the upper limit (second upper limit output value) of the output of the inverter at the time of power failure is set to a value higher than the upper limit (first upper limit output value) of the output of the inverter at the time of non-power failure. That is, the inverter is controlled such that the upper limit of the output of the inverter at the time of power failure is higher than the upper limit of the output of the inverter at the time of non-power failure. Therefore, even when the output voltage of the inverter is stepped down by the transformer at the time of a power failure, the decrease in the free standing output due to the conversion efficiency of the transformer is compensated for by the increase in the upper limit of the output of the inverter. For this reason, a self-supporting output can be made into the same grade as a grid connection output, and, thereby, the distributed power supply device with high merchandiseability can be provided. In addition, by correcting the output of the inverter by the correction unit, the voltage on the secondary side of the transformer, that is, the output voltage of the stand-alone power supply device at the time of a power failure, is accurately made the target voltage, for example, AC 100V. Can.

  Further, according to the present invention, the upper limit (the second upper limit current value) of the output current of the power generation device at the time of the power failure is higher than the upper limit (the first upper limit current value) of the output current of the power generation device at the time of the blackout It is set. That is, the boost converter is controlled such that the upper limit of the output current of the power generation device at the time of power failure is higher than the upper limit of the output current of the power generation device at the time of non-power failure. Therefore, more current can be supplied to the step-up converter at the time of power failure, whereby the output of the inverter at the time of power failure can be made larger than the output of the inverter at the time of non-power failure. As a result, it is possible to make the independent output the same level as the interconnection output.

  Further, the second upper limit output value may be determined based on the conversion efficiency of the transformer. According to this, by determining the second upper limit output value based on the conversion efficiency of the transformer, it is possible to compensate for the decrease in the free standing output caused by the fact that the conversion efficiency of the transformer is not 100%. In this case, the second upper limit output value may be determined based on the conversion efficiency of the transformer and the first upper limit output value such that the upper limit of the secondary side output of the transformer becomes the first upper limit output value.

  In addition, the second upper limit current value may be determined based on the second upper limit output value. Specifically, the second upper limit current value may be determined such that the upper limit of the output of the inverter reaches the second upper limit output value at the time of a power failure. According to this, it is possible to obtain an output corresponding to the second upper limit output value on the output side of the inverter at the time of a power failure.

  In addition, the power generation device may be a fuel cell power generation device. When the power generation device is a fuel cell power generation device, the upper limit value of the output current is generally set in order to prevent the deterioration thereof. In the present invention, the fuel cell power generation is performed by setting the upper limit value of the output current of the power generation device to the first upper limit current value during a power failure and setting the upper limit value of the output current of the power generation device to a second upper limit current value during a power failure. Deterioration of the device is prevented.

  In addition, it is preferable that the output voltage of the inverter is 200 V AC and the secondary voltage of the transformer is 100 V AC. According to this, it is possible to take out the power of AC 100 V from the stand-alone power supply device at the time of the power failure.

It is a block diagram of a distributed power supply device concerning this embodiment. It is a flowchart which shows the flow of the switching control processing routine which a switching control part performs. It is a flowchart which shows the flow of the converter control processing routine which a boost converter control part performs. It is a flowchart which shows the flow of the inverter control processing routine which an inverter control part performs. It is a flow chart which shows the flow of the independent output amendment processing routine which an independent output amendment part performs.

  Hereinafter, embodiments of the present invention will be described. FIG. 1 is a block diagram of a distributed power supply device according to the present embodiment. As shown in FIG. 1, the distributed power supply device 1 includes a fuel cell power generation device 2, a grid connection device 3, a stand-alone power supply device 4, and a control device 5.

  Although not shown, the fuel cell power generation device 2 is connected to a commercial power source C, and is driven by the power supplied from the commercial power source C. When the commercial power source C loses power during operation of the fuel cell power generation device 2, the fuel cell power generation device 2 generates electric power generated by itself or electric power from an internal battery provided in the distributed power supply device 1. It is driven.

  In the present embodiment, a solid oxide fuel cell (SOFC) is used as the fuel cell power generation device 2. SOFC is a fuel cell that uses solid oxide as an electrolyte as is well known, and generates direct current by generating electricity by reaction of fuel gas and air. The operating temperature of the SOFC is very high, about 500 ° C to 700 ° C. Since the system is operated at a very high temperature, a heat supply device utilizing the heat can be attached to the distributed power supply device 1 to construct a cogeneration device that supplies heat together with electricity.

  The grid connection device 3 is used to link the distributed power supply device 1 to the commercial power source C. The grid interconnection device 3 includes the boost converter 6, the inverter 7, the interconnection switching device 8, and connection paths connecting these components (a first connection path 9, a second connection path 10, and a third connection). And 11).

  The boost converter 6 is connected to the fuel cell power generation device 2 via the first connection 9. The direct current generated by the fuel cell power generation device 2 is input to the boost converter 6 via the first connection 9. The boost converter 6 boosts the DC voltage generated by the fuel cell power generation device 2. For example, the direct current of 70 V generated by the fuel cell power generation device 2 is boosted to 400 V.

  The inverter 7 is connected to the boost converter 6 via the second connection 10. The direct current boosted by the boost converter 6 is input to the inverter 7 via the second connection path 10. The inverter 7 converts the input direct current (the direct current boosted by the boost converter 6) into an alternating current synchronized with the alternating current output from the commercial power supply C, that is, an alternating current having the same frequency as the alternating current output from the commercial power supply C. Convert. Further, in the present embodiment, the inverter 7 outputs an alternating current of 200 V AC. A smoothing capacitor 25 is provided in the second connection path 10.

  Moreover, the output side of the inverter 7 is connected to the commercial power supply C by the third connection path 11 (connection path for interconnection). The alternating current converted by the inverter 7 flows through the third connection path 11. An interconnection switching device 8 is interposed in the middle of the third connection path 11. The connection switching device 8 blocks or connects the third connection path 11.

  The stand-alone power supply device 4 is configured to be able to supply power to the power load when the commercial power source C fails. The stand-alone power supply device 4 includes an auto transformer 12, a stand-alone switching device 13, a stand-alone power supply unit 14, and a stand-alone connection path 15 connecting the auto transformer 12 and the stand-alone power supply unit 14.

  As is well known, the autotransformer 12 (one-turn transformer) is a transformer in which a part of the winding is shared by the primary side and the secondary side. The primary side of the autotransformer 12 is connected to a portion of the third connection path 11 between the inverter 7 and the interconnection switching device 8 via the branch path 24. Further, the secondary side of the autotransformer 12 is connected to the stand-alone power supply unit 14 via the stand-alone connection path 15. The stand-alone power supply unit 14 is formed of, for example, a socket plug attached to the housing of the distributed power supply 1. The autotransformer 12 steps down the voltage of the alternating current applied to its primary side, and outputs the stepped-down alternating current to the secondary side. In the present embodiment, a voltage of half the voltage applied to the primary side is applied to the secondary side of the autotransformer 12. Therefore, from the secondary side of the autotransformer 12, an alternating current having a voltage (AC 100 V) which is half the output voltage (AC 200 V) of the inverter 7 is output.

  The switching device 13 for self-supporting is interposed in the connection path 15 for self-supporting. The switching device for self-supporting 13 cuts off or connects the connection path 15 for self-supporting.

  The control device 5 is configured by a microcomputer including a CPU, a ROM, and a RAM. The control device 5 is connected to the commercial power source C, and is driven based on the power supplied from the commercial power source C. When the commercial power source C loses power during operation of the control device 5, the control device 5 uses the power generated by the fuel cell power generation device 2 or the power from the internal battery provided in the distributed power supply device 1. , Driven.

  As shown in FIG. 1, the control device 5 includes a switching control unit 16, a boost converter control unit 17, and an inverter control unit 18. The switching control unit 16 controls the switching operation of the interconnection switching device 8 (that is, the disconnection and connection of the third connection path 11) and the switching operation of the switching device for self-supporting 13 (that is, the disconnection and connection of the connection path 15 for self-supporting). Do. The boost converter control unit 17 controls the operation of the boost converter 6. The inverter control unit 18 controls the operation of the inverter 7.

  Also, the distributed power supply device 1 includes a first current sensor 19, a second current sensor 20, a first voltage sensor 21, and a second voltage sensor 22. The first current sensor 19 is interposed in the first connection path 9 and detects the output current value i1 of the fuel cell power generation device 2, that is, the DC current value input to the step-up converter 6, and the detected current A signal corresponding to the value i1 is output to the control device 5. The second current sensor 20 is interposed in the third connection path 11 and detects an output current value i2 of the inverter 7 and outputs a signal corresponding to the detected current value i2 to the control device 5. The first voltage sensor 21 is also interposed in the third connection path 11 and detects an output voltage value V2 of the inverter 7 and outputs a signal corresponding to the detected voltage value V2 to the control device 5. The second voltage sensor 22 is interposed in the stand-alone connection path 15 and detects the secondary voltage value V3 of the autotransformer 12 and outputs a signal corresponding to the detected voltage value V3 to the control device 5 .

  Although not shown, a start button and a stop button are attached to a housing provided in the distributed power supply device 1. When the user presses the activation button, the operation of the distributed power supply 1 is started. Also, when the user presses the stop button, the operation of the distributed power supply 1 is stopped. The start button and the stop button may be attached to a remote controller (not shown), and the remote controller may be attached to the housing.

  In the distributed power supply device 1 having the above configuration, when the user presses the start button, the control device 5 is driven by supplying power from the commercial power supply C to the control device 5. Then, the control device 5 outputs an operation start command to the fuel cell power generation device 2. As a result, electric power is supplied from the commercial power source C to the fuel cell power generation device 2 to operate the fuel cell power generation device 2 and power generation is started.

  When the start button is pressed, the switching control unit 16 of the control device 5 executes the switching control process. FIG. 2 is a flowchart showing the flow of the switching control processing routine executed by the switching control unit 16. When this routine starts, the switching control unit 16 first determines whether the commercial power source C is uninterrupted at step 101 (hereinafter, step number is abbreviated as S), that is, power is supplied from the commercial power source C. It is judged whether it is done or not. If the commercial power source C is uninterrupted (S101: Yes), the switching control unit 16 outputs a connection signal to the interconnection switching device 8 (S102). As a result, the interconnection switching device 8 connects the third connection path 11. Next, the switching control unit 16 outputs the shutoff signal to the switching device for self-supporting 13 (S103). Thereby, the switching device 13 for self-supports interrupts the connection path 15 for self-supporting.

  When it is determined in S101 that the commercial power source C has a power failure (S101: No), the switching control unit 16 outputs a shutoff signal to the interconnection switching device 8 (S104). As a result, the interconnection switching device 8 shuts off the third connection path 11. Next, the switching control unit 16 outputs a connection signal to the switching device for self-supporting 13 (S105). Thereby, the switching device 13 for self-supporting connects the connection path 15 for self-supporting.

  After executing the process of S103 or the process of S105, the switching control unit 16 proceeds the process to S106. In S106, the switching control unit 16 determines whether the stop button has been pressed. When the stop button is not pressed (S106: No), the switching control unit 16 returns the process to S101 and repeats the above-described process. On the other hand, when the stop button is pressed (S106: Yes), the switching control unit 16 ends this routine.

  When the switching control unit 16 executes the above-described switching control processing routine, the connection of the third connection path 11 is established and the connection path for self-sustaining 15 is shut off when the commercial power source C does not have a power failure. Therefore, the direct current generated by the fuel cell power generation device 2 is supplied to the commercial power source C as AC 200 V AC synchronized with the AC of the commercial power source C via the boost converter 6 and the inverter 7. On the other hand, at the time of a power failure of the commercial power source C, the third connection path 11 is cut off and the connection of the self-supporting connection path 15 is established. Therefore, the direct current generated by the fuel cell power generation system 2 is input to the primary side of the autotransformer 12 via the boost converter 6, the inverter 7 and the branch path 24. Then, after being stepped down to AC 100 V by the autotransformer 12, power is supplied to the power supply unit 14 for stand-alone use. Therefore, by connecting the power load to the stand-alone power supply unit 14 at the time of the power failure, the power load can be driven even at the time of the power failure.

  In addition, after the start button is pressed, the boost converter control unit 17 of the control device 5 executes the converter control process. FIG. 3 is a flowchart showing the flow of a converter control processing routine executed by the boost converter control unit 17. When this routine starts, boost converter control unit 17 first determines in S111 of FIG. 3 whether commercial power supply C is uninterrupted.

If commercial power supply C is uninterrupted (S111: Yes), boost converter control unit 17 sets upper limit current value i _L to 10 A (S112). On the other hand, when the commercial power supply C has a power failure (S111: No), the boost converter control unit 17 sets the upper limit current value i _L to 10.55A. The upper limit current value i _L (= 10 A) set in S112 is the first upper limit current value (i _{L_1} ) in the present invention, and the upper limit current value i _L (= 10.55 A) set in S113 is And the second upper limit current value (i _{L_2} ) in the present invention.

After setting the upper limit current value i _L in S112 or S113, the boost converter control unit 17 sets the current input to the boost converter 6, that is, the upper limit of the output current of the fuel cell power generation device 2 to the upper limit current value i _L. The direct current supplied from the fuel cell power generator 2 is boosted (S114). The output current of the fuel cell power generation device 2 can be obtained from the current value i1 detected by the first current sensor 19.

The DC generated by the fuel cell power generation device 2 is limited so that the upper limit of the output current of the fuel cell power generation device 2 is limited to 10 A (first upper limit current value i _{L_1} ) during non-power failure by execution of the process of S114. Power generation by the fuel cell power generation device 2 is performed so that the upper limit of the output current value of the fuel cell power generation device 2 is limited to 10.55 A (the second upper limit current value i _{L_2} ). The direct current thus generated is boosted by the boost converter 6. In this way, by limiting the output current value of the fuel cell power generation device 2, acceleration of the deterioration of the fuel cell power generation device 2 due to the output current of the fuel cell power generation device 2 being excessive is prevented.

  After executing the process of S114, boost converter control unit 17 determines whether the stop button has been pressed (S115). When the stop button is not pressed (S115: No), boost converter control unit 17 returns the process to S111, and repeats the above process. On the other hand, if the stop button is pressed (S115: Yes), boost converter control unit 17 outputs a control stop command to boost converter 6 (S116). Thereby, boosting by the boost converter 6 is stopped. Thereafter, boost converter control unit 17 ends this routine.

Further, after the start button is pressed, the inverter control unit 18 of the control device 5 executes the inverter control processing. FIG. 4 is a flowchart showing the flow of the inverter control processing routine executed by the inverter control unit 18. When this routine starts, the inverter control unit 18 first determines at S121 in FIG. 4 whether or not the commercial power source C is uninterrupted. When the commercial power supply C is determined to be non-power failure (S121: Yes), the inverter control unit 18 sets an upper limit output value _{W L} to 700 W (S122). When it is determined that the commercial power supply C is a power failure (S121: No), the inverter control unit 18 sets an upper limit output value _{W L} to 738W. The upper limit output value W _L (= 700 W) set in S122 is the first upper limit output value (W _{L_1} ) in the present invention, and the upper limit output value W _L (= 738 W) set in S123 is the main limit. It is a second upper limit output value (W _{L_2} ) in the invention.

At S122 or S123 after setting the upper output value _{W L,} the inverter control unit 18 controls the inverter 7 so that the upper limit of the output of the inverter 7 is limited to the upper limit output value _{W L} (S124). Thereby, the direct current boosted by the boost converter 6 is converted to an alternating current of 200 V AC. In this case, the maximum output of the inverter 7 at the time of non-power failure is 700 W (first upper limit output value W _{L_1} ), and the maximum output of the inverter 7 at the time of power failure is 738 W (second upper limit output value W _{L_2} ). Further, the output of the inverter 7 is the product (V2 × i2) of the output current value i2 of the inverter 7 detected by the second current sensor 20 and the output voltage value V2 of the inverter 7 detected by the first voltage sensor 21 Determined by

  Thereafter, the inverter control unit 18 determines in S125 whether or not the stop button is pressed. When the stop button is not pressed (S125: No), the inverter control unit 18 returns the process to S121 and repeats the above-described process. On the other hand, when the stop button is pressed (S125: Yes), the inverter control unit 18 outputs a control stop command to the inverter 7 (S126). Thereby, the operation of the inverter 7 is stopped. Thereafter, the inverter control unit 18 ends this routine.

  When switching control unit 16, boost converter control unit 17, and inverter control unit 18 execute the above-described control, at the time of a power failure, up to 700 W of alternating current (AC 200 V, 3.5 A) is output from inverter 7 Ru. The alternating current output from the inverter 7 is supplied to the commercial power source C (system interconnection) via the third connection path 11 and the interconnection switching device 8. Thus, in the present embodiment, the interconnection output is 700 W.

  On the other hand, at the time of a power failure, a maximum of 738 W of alternating current (AC 200 V) is output from the inverter 7. The alternating current output from the inverter 7 is supplied to the primary side of the autotransformer 12 via the third connection path 11 and the branch path 24. In the autotransformer 12, the voltage applied to its primary side is stepped down, and an alternating current of AC 100 V is applied to its secondary side. Here, in the present embodiment, the conversion efficiency of the autotransformer 12 is about 95%. That is, the output of 5% in the autotransformer 12 is lost. Accordingly, the maximum power of 738 W input to the primary side of the autotransformer 12 is stepped down by the autotransformer 12, whereby the secondary side output of the autotransformer 12 is reduced to 95% of 738W, that is, about 700W.

  A maximum of 700 W AC (AC 100 V, 7 A) generated on the secondary side of the autotransformer 12 is supplied to the power supply unit 14 for stand-alone via the connection path 15 for stand-alone and the switching device 13 for stand-alone. Therefore, at the time of a power failure, 700 W of electric power can be supplied to the electric power load, for example, an important electric power load such as a refrigerator at the stand-alone power supply unit 14. Thus, in the present embodiment, the free standing output is 700 W, which is the same as the linked output.

  According to the present embodiment, as described above, the upper limit (738 W) of the output of the inverter 7 at the time of power failure is higher than the upper limit (700 W) of the output of the inverter 7 at the time of non-power failure. Therefore, even when the output voltage of the inverter 7 is stepped down by the autotransformer 12 at the time of a power failure, the independence due to the conversion efficiency (95%) of the autotransformer 12 is increased by the increased upper limit of the output of the inverter 7 The reduction in output is compensated. For this reason, a stand-alone output can be made into the same grade (700 W) as a grid connection output, and, thereby, the distributed power supply 1 with high merchandiseability can be provided.

Further, in the present embodiment, the upper or second upper output value _W L_2 the output of the inverter 7 during the power failure (738W), the upper limit or first upper output value _W L_1 the output of the inverter 7 during the non-power failure (700 W) And the conversion efficiency (95%) of the autotransformer 12. Specifically, the second upper output value _W L_2 (738W) is the secondary side of the autotransformer 12, such that the first upper output value _W L_1 the same power as (700 W) can be generated is determined . More specifically, the second upper output value _W L_2 (738W), the first upper limit output value _W L_1 (700 W), is set to a value conversion efficiency of greater than or equal to the value obtained by dividing (95%) of the autotransformer 12 Ru. By setting the upper limit (second upper limit output value) of the output of the inverter 7 at the time of a power failure in this manner, it is possible to compensate for the decrease in the independent output caused by the conversion efficiency of the autotransformer 12.

  In addition, at the time of a power failure, the direct current input by boost converter 6 is boosted so that the upper limit of the output current of fuel cell power generation device 2 is limited to 10 A, and at the time of a power failure, the upper limit of the output current of fuel cell power generation device 2 is 10 The boost converter 6 boosts the direct current input so as to be limited to 55A. According to this, by restricting the upper limit of the output current of the fuel cell power generation device 2 to 10 A or less or 10.55 A or less, it is possible to prevent the promotion of the deterioration of the fuel cell power generation device 2. Therefore, the long life of the fuel cell power generation device 2 can be achieved while securing the power of 700 W.

  In addition, the upper limit of the output current of the fuel cell power generation device 2 is 10 A at the time of non-power failure, while the upper limit of the output current of the fuel cell power generation device 2 is 10.55 A higher than 10 A at the time of power failure. That is, at the time of a power failure, the upper limit of the output current of the fuel cell power generation system 2 is increased, whereby the upper limit of the current value is relaxed. In the present embodiment, the reason why the upper limit of the output current of the fuel cell power generation device 2 at the time of the blackout is thus made higher than the upper limit of the fuel cell power generation device 2 at the time of the blackout is explained as follows.

  It is assumed that the output of the combustion cell generator 2 is 770 W and the output voltage of the fuel cell generator 2 is 70 V when the commercial power source C fails. In this case, the output current of the fuel cell power generation device 2 is theoretically 11A. However, when the upper limit of the output current of the fuel cell power generation device 2 is limited to 10 A, the output current of the fuel cell power generation device 2 is 10 A, so the output is 700 W.

  When the output of the fuel cell power generation system 2 is 700 W, the DC power input to the inverter 7 is also 700 W. For this reason, the output of the inverter 7 does not reach 738 W, and as a result, the free standing output is a power obtained by multiplying the output (700 W) of the inverter 7 by the conversion efficiency (95%) of the auto transformer 12, ie, 665 W (AC 100 V). Be done. That is, when the upper limit of the output current of the fuel cell power generation device 2 is limited to 10 A at the time of a power failure, the electric power of 665 W is output from the independent power supply device 4. In other words, when the upper limit value of the output current of the fuel cell power generation device 2 is limited to 10 A at the time of a power failure, 700 W of power can not be obtained from the stand-alone power supply device 4.

  On the other hand, when the upper limit of the output current of the fuel cell power generation device 2 is limited to 10.55 A, the output current of the fuel cell power generation device 2 is 10.55 A, and the output is 738 W. The direct current from the fuel cell power generation device 2 is converted to an alternating current of 738 W by the inverter 7 and then stepped down by the autotransformer 12. At this time, the secondary side output of the autotransformer 12 is 95% of 738 W, that is, about 700 W (AC 100 V). That is, when the upper limit value of the output current of the fuel cell power generation device 2 is limited to 10.55 A at the time of a power failure, 700 W of electric power can be obtained from the autonomous power supply device 4.

  As can be understood from the above, by making the upper limit of the output current of the fuel cell power generation device 2 at the time of a power failure higher than the upper limit of the output current of the fuel cell power generation device 2 at the time of a non-power failure, Can be supplied. Therefore, it is possible to avoid the occurrence of a situation where the output of the inverter 7 does not reach the target output (the second upper limit output value) due to the current limitation of the output current of the fuel cell power generation device 2. Therefore, it is possible to maintain the stand-alone output at 700 W at the time of the power failure.

  Note that there is a possibility that deterioration of the fuel cell power generation device 2 may be promoted by increasing the upper limit of the output current of the fuel cell power generation device 2 at the time of power failure, but in the case of a power failure in a short time Since the upper limit of the output current of the fuel cell power generation device 2 is increased only at the time of the power failure, the deterioration of the fuel cell power generation device 2 does not progress so much only at the time of the power failure. That is, according to the present embodiment, the self-supporting output can be maintained to the same degree as the interconnection output without advancing the deterioration of the fuel cell power generation device 2 so much.

In the present embodiment, the second upper limit current value i _{L_2} is the upper limit of the output current of the fuel cell power plant 2 during a power failure _(10.55A), the second upper limit inverter control unit 18 is set at the time of power failure It is determined based on the output value _W L_2 (738W). Specifically, the second upper limit current value i _{L_2} is determined such that the upper limit of the output of the inverter 7 reaches the second upper limit output value W _{L_2} at the time of a power failure. By setting the upper limit of the output current of the fuel cell power generator 2 at the time of a power failure in this manner, it is possible to compensate for the decrease in the self-sustaining output caused by the conversion efficiency of the autotransformer 12.

Further, in the present embodiment, the second upper limit current value _i L_2 for the first upper limit current value _i L_1 (10A) ratio _{(10.55A) (i L_2 / i} L_1), and the first upper output value _{W L_1} ( the ratio of the second upper output value _W L_2 (738W) for _{700W) (W L_2 / W L_1} ) is about 1.055. The ratio of _(i L_2 _/ i _{L_1)} and the ratio _(W L_2 _/ W _{L_1),} by setting the range of 1.04 or more and 1.06 or less, while suppressing the progress of deterioration of the fuel cell power plant 2, the power failure The self-sustaining output at time can be made the same degree as the interconnection output at the time of non-power failure.

  Further, in the present embodiment, as shown in FIG. 1, the inverter control unit 18 of the control device 5 may include a self-supporting output correction unit 18 a. The stand-alone output correction unit 18 a executes the stand-alone output correction process, whereby the power obtained by the stand-alone power supply device 4 at the time of a power failure is accurately converted to AC 100 V AC. FIG. 5 is a flowchart showing the flow of the independent output correction processing routine executed by the independent output correction unit 18a. When this routine is started, the stand-alone output correction unit 18a first determines in S131 of FIG. 5 whether the commercial power source C has a power failure. When the commercial power source C does not have a power failure (S131: No), the stand-alone output correction unit 18a ends this routine. On the other hand, when the commercial power source C has a power failure (S131: Yes), the stand-alone output correction unit advances the process to S132.

  In S132, the stand-alone output correction unit 18a determines whether the secondary voltage value V3 of the autotransformer 12 detected by the second voltage sensor 22 exceeds 100V. When the secondary voltage value V3 exceeds 100 V (S132: Yes), the stand-alone output correction unit 18a slightly reduces the on-duty ratio of the switching element of the inverter 7. As a result, the output voltage of the inverter 7 slightly decreases, and the secondary voltage value V3 of the autotransformer 12 also decreases slightly.

  On the other hand, if it is determined in S132 that the secondary voltage value V3 does not exceed 100 V (S132: No), the independent output correction unit 18a proceeds to S134 and the secondary voltage value V3 is 100 V. Determine if it is less than. When it is determined in S134 that the secondary voltage value V3 is not less than 100 V (S134: No), the secondary voltage value V3 is 100 V. In this case, since the output does not need to be corrected, the independent output correction unit 18a ends this routine.

  When it is determined in S134 that the secondary voltage value V3 is less than 100 V (S134: Yes), the stand-alone output correction unit 18a slightly increases the on-duty ratio of the switching element of the inverter 7. As a result, the output voltage of the inverter 7 slightly rises, and the secondary voltage value V3 of the autotransformer 12 also slightly rises accordingly.

  After changing the on-duty ratio of the switching element of the inverter 7 in S133 or S134, the stand-alone output correction unit 18a determines whether the stop button is pressed (S136). When the stop button is not pressed (S136: No), the stand-alone output correction unit 18a returns the process to S131 and repeats the above-described process. On the other hand, when the stop button is pressed (S136: Yes), the control of the inverter 7 based on this routine is stopped. Thereafter, this routine ends.

  By executing the above-described stand-alone output correction processing by the stand-alone output correction unit 18a, the voltage of the power obtained from the stand-alone dedicated power supply unit at the time of a power failure can be accurately made AC 100 V voltage.

  As mentioned above, although embodiment of this invention was described, this invention should not be limited to the said embodiment. For example, although the example which uses a fuel cell power generation device as a power generation device was explained in the above-mentioned embodiment, as long as it is a power generation device which generates direct current, other power generation devices, such as a solar power generation device, may be used. The present invention can be modified without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... dispersion type power supply device, 2 ... fuel cell power generation device (power generation device), 3 ... grid interconnection device, 4 ... independent power supply device, 5 ... control device, 6 ... boost converter, 7 ... inverter, 8 ... interconnection Switching device, 9: first connection path, 10: second connection path, 11: third connection path (interconnection connection path), 12: auto transformer (transformer), 13: switching device for self-supporting, 14: self-supporting Power supply part 15: connection path for self-supporting, 16: switching control part, 17: boost converter control part, 18: inverter control part, 18a: self-supporting output correction part (correction part), 19: first current sensor, 20 ... second current sensor, 21 ... first voltage sensor, 22 ... second voltage sensor, 24 ... branch path, C ... commercial power supply, i _{L_1} ... first upper limit current value, i _{L_2} ... second upper limit current value, _{WL_1} ... First upper limit output value, W _{L_2} ... Second upper limit output value

Claims (5)

A generator that generates direct current,
A step-up converter for boosting the voltage of direct current generated by the power generation apparatus; an inverter for converting the direct current boosted by the step-up converter into alternating current synchronized with alternating current output from a commercial power source; A grid interconnection device having a grid connection path connected to the commercial power source, and a grid switching device interposed in the grid connection path and blocking or connecting the grid connection path.
The primary side of the interconnection connection path is connected to a portion between the inverter and the interconnection switching device, and the output voltage of the inverter is stepped down, and an alternating current that is stepped down is output to the secondary side. Switching device for blocking or connecting the stand-alone connection path, the stand-alone connection path connected to the secondary side of the transformer, the stand-alone power supply unit connected to the stand-alone connection path, and the stand-alone connection path A self-supporting power supply device having
The grid connection is connected and the stand-alone connection is shut off when the commercial power fails. The grid connection is shut and the stand-alone connection is shut off when the commercial power fails. A switching control unit that controls the interconnection switching device and the self-supporting switching device to be connected;
The boost converter is controlled such that the upper limit of the output current of the power generation device is limited to the first upper limit current value during the non-power failure, and the upper limit of the output current of the power generation device is the first upper limit current during the power failure A boost converter control unit configured to control the boost converter to be limited to a second upper limit current value higher than a value;
The inverter is controlled such that the upper limit of the output of the inverter is limited to the first upper limit output value during the non-power failure, and the upper limit of the output of the inverter is higher than the first upper limit output value during the power failure An inverter control unit that controls the inverter to be limited to two upper limit output values;
And a voltage sensor for detecting a voltage value on the secondary side of the transformer ,
The inverter control unit, during the power failure, based on the voltage detected by the voltage sensor, that having a correcting unit for correcting the output of the inverter, the distributed power supply. In the distributed power supply device according to claim 1,
The distributed power supply device, wherein the second upper limit output value is determined based on the conversion efficiency of the transformer. The distributed power supply device according to claim 1 or 2
The distributed power supply device, wherein the second upper limit current value is determined based on the second upper limit output value. The distributed power supply device according to any one of claims 1 to 3.
The distributed power supply device, wherein the power generation device is a fuel cell power generation device. The distributed power supply device according to any one of claims 1 to 4 ,
The distributed power supply apparatus, wherein the output voltage of the inverter is 200 V AC and the secondary voltage of the transformer is 100 V AC.

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