JP2016032378A - Control method for power control system, power control system, and power controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a system capable of managing efficient operation control among a plurality of distributed power supplies without compromising the versatility of the distributed power supply side.SOLUTION: There is provided a control method for a power control system comprising a power generator for generating power during a period in which a first current sensor detects a forward power flow, a power controller for controlling distributed power supplies including the power generator, and a second current sensor for detecting current flowing in a load. The power controller is connected to a pseudo output unit capable of supplying pseudo current to the first current sensor. The control method for the power control system includes the steps of: detecting a value of a first forward power flow current flowing from a system and the power controller to the load in a state in which the pseudo current stops; if the current detected by the second current sensor has increased, detecting a value of a second forward power flow current when a value of current flowing from the system and the power controller to the load increases and then becomes a steady state value; and storing the value of the second forward power flow current as a threshold.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a control method for a power control system, a power control system, and a power control apparatus.

  As a power generation conditioner for a power generation system equipped with power generation equipment such as a solar panel, the grid connection operation that outputs AC power in connection with a commercial power system (hereinafter abbreviated as system as appropriate) and the system There are known ones that enable independent operation that outputs alternating current power (see, for example, Patent Document 1).

  Further, as a power storage power conditioner of a power storage system including a power storage facility such as a storage battery that is charged by system power, as in the case of the power generation power conditioner described above, In addition, a device that enables independent operation to output AC power regardless of the system is known (see, for example, Patent Document 2).

JP 2007-049770 A JP 2008-253033 A

  By the way, in a power control system, it is required to centrally manage and operate a plurality of distributed power sources such as a solar battery, a storage battery, a fuel cell, and a gas generator. In particular, it is required to construct a system capable of managing efficient operation control among a plurality of distributed power sources without destroying the versatility on the distributed power source side.

  Accordingly, an object of the present invention made in view of the above problems is to provide a power control system capable of managing efficient operation control among a plurality of distributed power sources without destroying the versatility on the distributed power source side. A control method, a power control system, and a power control apparatus are provided.

  In order to solve the above-mentioned problems, the control method of the power control system according to the present invention is based on the value detected by the first current sensor while the first current sensor detects the forward current exceeding the threshold. A control method for a power control system, comprising: a power generation device that performs power generation; a power control device that controls a distributed power source including the power generation device; and a second current sensor that detects a current flowing through a load. One current sensor is disposed between the power control device and the power generation device, the second current sensor is disposed between the power control device and the load, and the power control device is disposed on the first current sensor. Connected to a pseudo output unit capable of supplying a pseudo current which is a current in the same direction as a forward power flow, and the load from at least one of a system and the power control device in a state where the pseudo current is stopped. Flow When the current detected by the second current sensor increases after the first step of detecting the current value as the first forward flow current value and after the first step, at least one of the system and the power control device A second step of detecting the current value when the current value flowing through the load increases from one side and then becomes a steady value as the second forward flow current value, and the second forward flow current value is stored as the threshold value. And a third step.

  Further, it is preferable that the second forward flow current value in the second step is measured a plurality of times, and the generated power of the power generator is set based on an average value thereof.

  The second forward flow current value is preferably a current value detected when the power generator follows the load.

  In order to solve the above-described problems, the power control system according to the present invention generates power in accordance with the value detected by the first current sensor while the first current sensor detects a forward flow greater than or equal to the threshold value. A power control system comprising: a power generation device to perform; a power control device for controlling a distributed power source including the power generation device; and a second current sensor for detecting a current flowing through a load, wherein the first current sensor is the power The second current sensor is disposed between the power control device and the load, and the power control device has a forward flow with respect to the first current sensor. Connected to a pseudo output unit capable of supplying a pseudo current that is a current in the same direction, the power control device includes a control unit and a storage unit, and the control unit is in a state where the pseudo current is stopped, Small number of grids and power control devices When a current value flowing from at least one of the loads to the load is detected as a first forward flow current value and the current detected by the second current sensor increases after the detection of the first forward flow current value, A current value flowing through the load from at least one of the grid and the power control device and then becoming a steady value is further detected as a second forward current value, and the second forward current A value is stored in the storage unit as the threshold value.

  In order to solve the above-described problems, the power control device according to the present invention generates power according to the value detected by the first current sensor while the first current sensor detects a forward current greater than or equal to the threshold value. And a power control device that controls a distributed power source including the power generation device, wherein the first current sensor is disposed between the power control device and the power generation device and detects a current flowing through a load. A second current sensor that is arranged between the power control device and a load, and the power control device can supply a pseudo current that is a current in the same direction as a forward current to the first current sensor. The power control device includes a control unit and a storage unit, and the control unit is configured to output the load from at least one of a system and the power control device in a state where the pseudo current is stopped. 1st normal tide A current flowing through the load from at least one of the system and the power control device when the current detected by the second current sensor increases after detection of the first forward flow current value. A current value when the value increases and then becomes a steady value is further detected as a second forward flow current value, and the second forward flow current value is stored in the storage unit as the threshold value.

  According to the control method, power control system, and power control apparatus of the power control system according to the present invention, efficient operation control among a plurality of distributed power supplies is managed without destroying the versatility on the distributed power supply side. It becomes possible.

1 is a block diagram of a power control system according to an embodiment of the present invention. It is a figure which shows the wiring regarding the pseudo output part in the electric power control system which concerns on one Embodiment of this invention. It is a figure which shows the example of control at the time of the grid operation of the electric power control system which concerns on one Embodiment of this invention. It is a figure which shows the control flow in pseudo-current determination mode. It is a figure which shows the change of the supply current from a power conditioner and an electric power generating apparatus when the electric current which flows into load increases. It is a figure which shows the example of control at the time of the self-sustained operation (at the time of discharge) of the electric power control system which concerns on one Embodiment of this invention. It is a figure showing an example of control at the time of self-sustained operation (at the time of charge) of a power control system concerning one embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment)
First, a power control system according to an embodiment of the present invention will be described. The power control system 100 according to the present embodiment includes a distributed power source that supplies power that can be sold and / or a distributed power source that supplies power that cannot be sold, in addition to power supplied from a system (commercial power system). Connect and use. A distributed power source that supplies power that can be sold is a system that supplies power by, for example, solar power generation. On the other hand, distributed power sources that supply power that cannot be sold include, for example, storage battery systems that can charge and discharge power, fuel cell systems that include fuel cells such as SOFC (Solid Oxide Fuel Cell), and gas that is generated by gas fuel Such as a generator system. In the present embodiment, a solar battery is provided as a distributed power source that supplies power that can be sold, and a storage battery and a power generator that is a fuel cell or a gas generator are provided as a distributed power source that supplies power that cannot be sold. An example is shown.

  FIG. 1 is a block diagram showing a schematic configuration of a power control system 100 according to an embodiment of the present invention. The power control system 100 according to the present embodiment includes a power conditioner 20 (power control device), a first current sensor 40, a pseudo output unit 50, and a power generation device 33. Moreover, the solar cell 11, the storage battery 12, the distribution board 31, the load 32, the 2nd current sensor 70, and the 3rd current sensor 71 which are used by connecting with the electric power control system 100 are shown according to FIG. Here, the power generation device 33 is configured by a fuel cell or a gas generator. The power control system 100 normally performs an interconnection operation with the grid, and supplies power supplied from the grid and power from each distributed power source (solar battery 11, storage battery 12, and power generation device 33) to the load 32. . The power control system 100 performs a self-sustained operation when there is no power supply from the system, such as during a power failure, and supplies power from each distributed power source (solar cell 11, storage battery 12, power generation device 33) to each load (load 32, The pseudo-current load 51) is supplied. In addition, when the power control system 100 performs a self-sustained operation, each distributed power source (solar cell 11, storage battery 12, power generation device 33) is in a state of being disconnected from the system, and the power control system 100 performs an interconnected operation. In this case, each distributed power source (solar cell 11, storage battery 12, power generation device 33) is in parallel with the system.

  In FIG. 1, a solid line connecting each functional block represents a wiring through which power flows, and a broken line connecting each functional block represents a control signal or a flow of information to be communicated. The communication indicated by the broken line may be wired communication or wireless communication. Various methods can be adopted for communication of control signals and information including each layer. For example, communication by a short-range communication method such as ZigBee (registered trademark) can be employed. In addition, various transmission media such as infrared communication and power line communication (PLC) can be used. In addition, various protocols such as ZigBee SEP 2.0 (Smart Energy Profile 2.0), ECHONET Lite (registered trademark), etc. are defined on lower layers including the physical layer suitable for each communication. A communication protocol may be operated.

  The solar cell 11 converts sunlight energy into DC power. The solar battery 11 is configured such that, for example, power generation units having photoelectric conversion cells are connected in a matrix, and a predetermined short-circuit current (for example, 10 A) is output. The type of solar cell 11 is not limited as long as it is capable of photoelectric conversion, such as a silicon-based polycrystalline solar cell, a silicon-based single crystal solar cell, or a thin-film solar cell such as CIGS.

  The storage battery 12 includes a storage battery such as a lithium ion battery or a nickel metal hydride battery. The storage battery 12 can supply electric power by discharging the charged electric power. In addition to the power supplied from the grid and the solar battery 11, the storage battery 12 can be charged with the power supplied from the power generation device 33 as described later.

  The power conditioner 20 (power control device) converts the DC power supplied from the solar battery 11 and the storage battery 12 and the AC power supplied from the grid and the power generation device 33, and performs grid-connected operation and independence. Operation switching control is performed. The power conditioner 20 includes DC / DC converters 13 and 14, an inverter 21, interconnection operation switches 22 and 23, an autonomous operation switch 24, a control unit 25 that controls the entire power conditioner 20, and a storage unit 26. With. The power conditioner 20 constitutes a so-called multi-DC link system that performs power control by connecting the power from the solar battery 11 and the storage battery 12 as DC. In addition, you may comprise so that the interconnection operation switch 23 may be taken out of the power conditioner 20. FIG.

  The DC / DC converters 13 and 14 step up or step down DC power from the solar battery 11 and the storage battery 12 to a predetermined voltage, respectively. The boost ratio in the DC / DC converters 13 and 14 may be a preset fixed value, or may be appropriately controlled by the control unit 25. The DC / DC converter 13 performs MPPT (Maximum Power Point Tracking) control on the generated power from the solar cell 11 and performs step-up or step-down to a predetermined voltage, which is suitable for solar cell power generation. It is a DC / DC converter. In the present embodiment, since the DC power from the solar battery 11 and the storage battery 12 is DC-linked, it is necessary to step up or step down to the same voltage. The DC / DC converter 14 is a bidirectional DC converter, and can convert the power from the system, the power generation device 33 and the solar battery 11 to charge the storage battery 12.

  The inverter 21 is a bidirectional inverter, which converts DC power supplied from the solar battery 11 and the storage battery 12 into AC power, and converts AC power supplied from the system and the power generator 33 into DC power. Convert to Note that the power conditioner 20 has a function of detecting the current output from the inverter 21.

  The interconnecting operation switches 22 and 23 and the self-supporting operation switch 24 are each configured by a relay, a transistor, and the like, and are on / off controlled. As illustrated, the self-sustaining operation switch 24 is disposed between the power generation device 33 and the storage battery 12. The interconnection operation switches 22 and 23 and the self-sustained operation switch 24 are switched via a state in which both are turned off so that they are not turned on at the same time. More specifically, when switching from independent operation to interconnection operation, the interconnection operation switches 22 and 23 are controlled to be turned on after the autonomous operation switch 24 is turned off. Further, when switching from the interconnection operation to the independent operation, the independent operation switch 24 is controlled to be turned on after the interconnection operation switches 22 and 23 are turned off. The above-described control of the interconnection operation switches 22 and 23 and the independent operation switch 24 can be realized by software by the control unit 25, for example. However, as an exception to the above control, when the power supply from each distributed power supply is off, only the interconnection operation switch 23 is turned on, and both the interconnection operation switch 22 and the independent operation switch 24 are turned off. Only power supply from the system to the distribution board 31 is performed.

  The control part 25 is comprised, for example with a microcomputer, and controls operation | movement of each part, such as the inverter 21, the interconnection operation switches 22 and 23, and the self-supporting operation switch 24, based on states, such as a raise of a system voltage or a power failure. The control unit 25 switches the interconnection operation switches 22 and 23 on and the independent operation switch 24 off during the interconnection operation. In addition, the control unit 25 switches the interconnection operation switches 22 and 23 off and the autonomous operation switch 24 on during the independent operation.

  In addition to various programs executed by the control unit 25, the storage unit 26 plays a role of storing current detection results and the like in each process as will be described later.

  The distribution board 31 distributes the power supplied from the grid during the grid operation to a plurality of branches and distributes it to the load 32. In addition, the distribution board 31 distributes the power supplied from a plurality of distributed power sources (solar cell 11, storage battery 12, power generation device 33) to a plurality of branches and distributes the load 32. Here, the load 32 is a power load that consumes power. For example, various electric appliances such as air conditioners, microwave ovens, and televisions used in homes, air conditioners and lighting equipment used in commercial and industrial facilities, and the like. Machine, lighting equipment, etc.

  The power generation device 33 is configured by a fuel cell or a gas generator. A fuel cell includes a cell that generates direct-current power through a chemical reaction with oxygen in the air using hydrogen, an inverter that converts the generated direct-current power into 100V or 200V AC power, and other accessories. Prepare. Here, the fuel cell as the power generation device 33 is a system that enables supply of AC power to the load 32 without using the power conditioner 20, and is always designed to be connected to the power conditioner 20. The system may be a versatile system. The gas generator generates power with a gas engine using a predetermined gas or the like as fuel.

  The power generation device 33 performs power generation while the corresponding first current sensor 40 detects a forward current (current in the power purchase direction), and performs load following operation that follows the power consumption of the load 32 during power generation or a predetermined rating. Performs rated operation according to the power value. The tracking range during load following operation is, for example, 200 to 700 W, and the rated power value during rated operation is, for example, 700 W. The power generation device 33 may perform a load following operation that follows the power consumption of the load 32 during the interconnected operation, and perform a load following operation or a rated operation based on the rated power value during the independent operation.

  The first current sensor 40 detects a current flowing between the system and the power generation device 33. In Japan, since the power generated by the power generation device 33 is defined as being unsellable, when the first current sensor 40 detects a reverse power flow (current in the power sales direction) to the grid side, the power generation device 33 is Stop power generation. While the first current sensor 40 detects a forward power flow equal to or greater than a predetermined threshold, the power generation device 33 performs power generation in a load following operation or a rated operation, assuming that power can be supplied to the load 32 from itself. Note that the first current sensor 40 can detect the current flowing between the system and the power generation device 33 and the current flowing between the power generation device 33 and the storage battery 12 in FIG. It is arranged between the distribution board 31.

  The first current sensor 40 according to the present embodiment has a ring shape, the power line from the system and the distributed power source penetrates the center, and the pseudo output line from the pseudo output unit 50 is wound by a predetermined number of turns. The The more the pseudo output line is wound around the first current sensor 40, the greater the pseudo current in the forward power flow direction can be detected with a minute current.

  The second current sensor 70 is a sensor provided to detect a current flowing from the power conditioner 20 or the power generation device 33 to the load 32. In the present embodiment, the second current sensor 70 is provided between the distribution board 31 and the load 32. Be placed.

  The third current sensor 71 is a sensor provided to detect a current flowing from the system to the load 32. In the present embodiment, the third current sensor 71 is disposed between the system and the power conditioner 20.

  Here, in the power control system 100 according to the present embodiment, in the state where the power generation device 33 and the storage battery 12 are disconnected from the system, a current in the same direction as the pseudo forward current flows to the first current sensor 40 through the pseudo output unit 50. Control is performed so that (pseudo-current) flows. As a result, the power generation device 33 can be rated and the power generated by the power generation device 33 can be stored in the storage battery 12. Hereinafter, power storage by the pseudo current through the pseudo output unit 50 will be described in detail.

  The pseudo output unit 50 can supply a pseudo current that is a current in the same direction as the forward power flow to the first current sensor 40. The pseudo output unit 50 is a system that receives power supply from the power conditioner 20 or the power generation device 33, and includes a pseudo current load 51, a synchronous switch 52, a pseudo current control switch 53, and a transformer 60. FIG. 2 is a diagram illustrating wiring related to the pseudo output unit 50. In FIG. 2, the system is a single-phase three-wire of 200V. In this case, one of the voltage lines and the neutral line are connected to the pseudo output unit 50 via the transformer 60. As illustrated, the connection line of the pseudo output unit 50 is wired so as to pass through the first current sensor 40 installed in each of the two voltage lines. The pseudo output unit 50 may be configured integrally with the power conditioner 20 or may be configured independent of the power conditioner 20. In the case of FIG. 2, one voltage line and a neutral line are connected to the transformer 60, but both voltage lines may be connected.

  The pseudo current load 51 is a load provided for current adjustment in the pseudo output unit 50. In the present embodiment, for the pseudo current load 51, for example, a variable resistance device whose resistance value can be controlled by the control unit 25 can be used. As the pseudo current load 51, a load outside the pseudo output unit 50 may be used. The synchronous switch 52 is for supplying a part of the electric power supplied from the power conditioner 20 or the power generator 33 to the pseudo output unit 50 to the first current sensor 40 as a pseudo current in the same direction as the forward flow. The pseudo current control switch 53 is for preventing unnecessary power generation due to the pseudo current. The synchronous switch 52 and the pseudo current control switch 53 are configured by independent relays, transistors, and the like, and are independently turned on / off by the control unit 25 of the power conditioner 20.

  As shown in FIGS. 1 and 2, the pseudo current load 51 and the pseudo current control switch 53 are connected in series. When both the synchronous switch 52 and the pseudo current control switch 53 are turned on, the pseudo current load 51 is simulated. Current flows.

  The transformer 60 serves to step down the power from the power conditioner 20 or the power generation device 33. In this embodiment, the turns ratio of the transformer 60 is 20, and the AC 100V power from the power conditioner 20 or the power generation device 33 is stepped down to 5V AC and then supplied to the pseudo current load 51. Since power is supplied to the pseudo-current load 51 after being stepped down by the transformer 60 in this manner, the pseudo-current load 51 can be reduced in size. Moreover, since the voltage applied to the switches 52 and 53 can be kept low, a cheaper product can be used for the switches 52 and 53. Further, when the power consumption in the pseudo current load 51 is the same, more pseudo current can be flowed.

  The synchronous switch 52 is ON / OFF controlled in synchronization with the self-sustaining operation switch 24 of the power conditioner 20. That is, the synchronous switch 52 is turned off during the interconnected operation and is turned on during the autonomous operation, like the autonomous operation switch 24. More specifically, the synchronous switch 52 is a switch that synchronizes the disconnection / parallel switching with the system and the switching timing, and is controlled so that a pseudo current flows when disconnecting and a pseudo current does not flow when parallel. The synchronous control of the independent operation switch 24 and the synchronous switch 52 is realized by hardware by branching the wiring of the control signal to the independent operation switch 24 to the synchronous switch 52. The synchronous control of the independent operation switch 24 and the synchronous switch 52 can also be realized by software by the control unit 25.

  The pseudo current control switch 53 is turned off when charging of the storage battery 12 is completed, and is turned on when charging is not completed. Here, the case where the charging of the storage battery 12 is completed indicates a case where the storage battery 12 is charged with electric power of a predetermined value or more. Note that the control unit 25 may be configured to determine whether or not charging is completed through communication with the storage battery 12. When charging of the storage battery 12 is completed and the pseudo-current control switch 53 is turned off during the self-sustaining operation, the pseudo-current does not flow through the first current sensor 40, so that unnecessary power generation by the power generator 33 can be stopped. Further, the pseudo current control switch 53 is also controlled to be turned off when shifting to a pseudo current determination mode described later.

  Here, the setting of the pseudo current value in the present embodiment will be described. The power generator 33 in the power control system 100 of the present embodiment can have a rated power value of 700 W, for example. However, in FIGS. 1 and 2, when the power generation device 33 outputs 700 W of power, the first current sensor 40 detects a current in the reverse flow direction corresponding to the output power of 700 W, and the power generation device 33 itself Will stop power generation.

  Therefore, in the present embodiment, power is supplied from the power conditioner 20 or the power generation device 33 to the pseudo output unit 50 so that a pseudo current for canceling the current in the reverse flow direction detected by the first current sensor 40 flows. Configure. For example, when the power generation device 33 outputs 700 W of reverse power flow, in order for the current detection in the first current sensor 40 to be 50 W of forward power detection, a pseudo current corresponding to the output power of 750 W flows. Thus, the pseudo output unit 50 needs to be configured.

Here, consider a case where the first current sensor 40 generates a pseudo current equivalent to 750 W of output power. When the output voltage of the distributed power source is AC 200V and the number of turns of the pseudo output line wound around the first current sensor 40 is 5, the pseudo current value I ₁ to be generated by the pseudo output unit 50 is calculated as follows. Is required.

I ₁ = 750/200/5 = 0.75 [A] Formula (1)

Next, a method for determining the resistance value R ₁ of the pseudo current load 51 for generating I ₁ will be described. As shown in FIG. 2, one of the voltage lines and a neutral line are connected to the pseudo output unit 50. Then, power is provided to the pseudo output unit 50 after the voltage of AC 100 V is stepped down to AC 5 V in the transformer 60. Accordingly, the resistance value R ₁ for generating I ₁ is obtained by the following calculation.

R ₁ = 5 / 0.75 = 6.7 [Ω] Formula (2)

The pseudo current value I ₁ and the resistance value R ₁ obtained by the above calculation are only one embodiment, the number of turns of the pseudo output line, the pseudo current value to be supplied to the first current sensor 40 (corresponding output power value). Depending on the above, various parameters can be selected.

  Hereinafter, a control example in the power control system 100 according to the present embodiment will be described in detail with reference to the drawings.

(Control during interconnected operation)
FIG. 3 is a diagram illustrating a control example of the power control system 100 during the interconnected operation. In this case, each switch of the power conditioner 20 is controlled such that the interconnection operation switches 22 and 23 are turned on and the independent operation switch 24 is turned off. In addition, each switch of the pseudo output unit 50 is controlled so that the synchronous switch 52 is off and the pseudo current control switch 53 is on or off according to the charge amount of the storage battery 12.

  At the time of the interconnection operation, as indicated by a thick arrow, AC 100V (or 200V) is supplied from the system, and power is supplied to the load 32. When the charging of the storage battery 12 has not been completed, the power conditioner 20 charges the storage battery 12 by converting AC power from the system into DC power. In addition, the power conditioner 20 can convert the generated power of the solar cell 11 into AC power and reversely flow into the system, or sell surplus power. In addition, the power conditioner 20 has a configuration capable of outputting power from the system and power from the distributed power source (solar battery 11 and storage battery 12) to the pseudo output unit 50, but the synchronous switch 52 is off during the interconnection operation. Therefore, the pseudo current is not supplied to the first current sensor 40. Since the forward current (current in the power purchase direction) flows from the system to the first current sensor 40, the power generation device 33 can perform load following operation and supply power to the load 32 through the distribution board 31.

  Next, the operation in the pseudo current determination mode during the interconnection operation will be described. Previously, the pseudo current value for causing the first current sensor 40 to flow a current in the forward current direction corresponding to 50 W has been described. However, how many watts of forward power flow the first current sensor 40 detects depends on the design, specifications, and the like of the power generation device 33. Therefore, in the present embodiment, a method is adopted in which a pseudo current value at which the power generation device 33 actually starts power generation is obtained by measurement.

  FIG. 4 shows a control flow in the pseudo-current determination mode at the time of interconnection operation.

During the interconnection operation as shown in FIG. 3, the control unit 25 shifts to a pseudo current determination mode for determining a pseudo current value. First, the control unit 25 monitors the output of the second current sensor 70 and determines whether or not the current i _load flowing through the load 32 has increased (step S102). The current waveform when the current i _load flowing through the load 32 increases is, for example, at time t ₁ in FIG. When determining that the current flowing through the load 32 has increased, the control unit 25 monitors the output current of the power conditioner 20 and the output of the current sensor 71 to supply the supply current _imdc from the power conditioner 20 and the supply from the system. The increase / decrease of the current i _grid is monitored (step S103). Since the power conditioner 20 cannot directly read the detection current of the first current sensor 40, the first current is detected by adding the detection current of the third current sensor 71 to the output current value of the power conditioner 20. A value corresponding to the detection current of the sensor 40 is calculated. When the detection current in the first current sensor 40 increases, the power generation device 33 increases its generated power so that the power supply from the system and the power conditioner 20 is reduced as much as possible. However, the power generation device 33 such as a fuel cell does not have sufficient followability when the current i _FC is increased following the load 32, and the current i _load flowing through the load 32 as shown in FIG. Follow with a certain delay time. On the other hand, the system and the power conditioner 20 can increase the supply current in response to an increase in the current i _load flowing through the load 32 as shown in FIG. Incidentally, with the relationship _{i load = (i mdc + i} grid) + i FC.

As shown in FIGS. 5B and 5C, when the output current i _FC of the power generator 33 starts to follow the current i _load of the load 32 at time t ₂ , the supply current from the power conditioner 20 and the system (I _mdc + i _grid ) starts to decrease and converges to a predetermined steady value at time t ₃ . The control unit 25 sets the supply current (i _mdc + i _grid ) from the power conditioner 20 and the system before and after the current i _{load of the} load 32 increases as a first forward flow current value and a second forward flow current value, respectively ( The data is stored in the storage unit 26 (shown in FIG. 5B) (step S104).

  The controller 25 performs the processes from step S102 to step S104 a predetermined number of times (step S101). The predetermined number of times can be, for example, 10 times. Then, the control unit 25 calculates an average value from the second forward flow current value for a predetermined number of times stored in the storage unit 26 (step S105). The control unit 25 determines the average value of the second forward current value calculated in step S105 as a threshold value of the forward current value (step S106), and ends the process. That is, the control unit 25 performs the pseudo current load in the pseudo output unit 50 so that the forward current equal to the average value of the second forward current values calculated in step S105 flows to the first current sensor 40 during the autonomous operation. The resistance value 51 is adjusted.

Thus, the average value of the second forward current value calculated in step S105 is a forward current threshold value required for the power generation device 33 to start power generation or a value exceeding the threshold value. The pseudo current may be adjusted so that the detected current in the one current sensor 40 becomes the average value of the second forward flow current values. In this embodiment, the average value of the second forward flow current value of the predetermined number of times is used. However, the minimum value of the second forward flow current value of the predetermined number of times may be used, and thus the current consumption Can be further suppressed. Note that the control unit 25 causes the pseudo-current to flow with the predetermined output power so that the power generation device 33 generates power with a predetermined output power after flowing the pseudo current and causing the power generation device 33 to start power generation. It may be further increased.

  Next, a calculation procedure for causing the forward current flowing in step S106 to flow through the first current sensor 40 during the independent operation will be described.

Here, a case will be described in which the power generation device 33 generates power at 700 W and 500 W of the power is consumed by the load 32. Since the output voltage of the distributed power is AC 200V, the reverse flow current I _r flowing in the first current sensor 40 by the power generation apparatus 33 generates power is obtained by the following equation (3).
I _r = (700−500) /200=1.0 [A] Formula (3)

When forward power flow current determined in step S106 it is assumed to be 0.15 [A], the pseudo current I _a to be detected to the first current sensor 40 is obtained by the following equation (3).
I _a = 1.0 + 0.15 = 1.15 [A] Formula (4)

When the number of turns of the pseudo output line wound around the first current sensor 40 is 5, the current I _a1 to be generated by the pseudo output unit 50 is obtained by the following equation (5).
I _a1 = 1.15 / 5 = 0.23 [A] Formula (5)

Since the voltage supplied by the pseudo output unit 50 as described above is lowered to 5V, the value R _a1 of the pseudo current load 51 to be configured for generating the current I _a1 is the following It is calculated | required by Numerical formula (6).
R _a1 = 5 / 0.23 = 22 [Ω] Formula (6)

Therefore, the control unit 25 may turn on the pseudo-current control switch 53 after setting the resistance value _Ra1 of the pseudo-current load 51 in the self-sustaining operation described later. As a result, the first current sensor 40 detects the forward flow current determined in step S <b> 106, so that it is possible to charge the storage battery 12 while supplying power from the power generation device 33 to the load 32. Note that the control unit 25 always monitors the current value corresponding to the current output of the first current sensor 40 even after the above control is started, and if there is a deviation from a predetermined forward current, the pseudo current load 51 is detected. It is preferable to adjust the value of.

(Control during autonomous operation)
Next, a control example of the power control system 100 during the independent operation will be described with reference to FIG. In this case, each switch of the power conditioner 20 is controlled such that the interconnection operation switches 22 and 23 are turned off and the independent operation switch 24 is turned on. Each switch of the pseudo output unit 50 is controlled such that the synchronous switch 52 is on and the pseudo current control switch 53 is off. In FIG. 6, it is assumed that charging of the storage battery 12 is completed.

  The thick line in FIG. 6 shows an example of power supply by the distributed power supply during the independent operation. In this example, the power conditioner 20 outputs the power of the distributed power source (solar battery 11 and storage battery 12) to the load 32 via the self-sustained operation switch 24. Moreover, since the 1st current sensor 40 detects the electric current of the forward power flow direction from a distributed power supply, the electric power generating apparatus 33 can perform load follow-up driving | operation.

  The operation in the pseudo current determination mode during the independent operation is almost the same as that during the interconnection operation. More specifically, since no power supply is received from the system during the independent operation, the supply current from the power conditioner 20 and the system is monitored in steps S103, S104, and S105 in FIG. Instead of storing the value, the supply current from only the power conditioner 20 may be monitored and the average value of the second forward current values may be stored. Note that the control unit 25 monitors the supply current and uses the second forward flow current value using the output current value of the power conditioner 20 and the detected current of the third current sensor 71 in both the grid operation and the independent operation. Therefore, there is no difference in the substantial operation of the control unit 25.

  Next, the case where the storage battery 12 is charged from the power generation device 33 will be described.

  FIG. 7 is a diagram illustrating a control example in the case where the power generation device 33 is generating electric power with a pseudo current during the autonomous operation. As shown in FIG. 7, when the power generation device 33 generates power during the independent operation, power is supplied to the pseudo output unit 50 by the power conditioner 20. The electric power supplied to the pseudo output unit 50 flows to the pseudo output line via the transformer 60 and is detected by the first current sensor 40 as a pseudo current. At this time, since the pseudo output unit 50 operates so that the first current sensor 40 detects the forward power flow (current in the power purchase direction), the power generation device 33 performs power generation. The distribution board 31 supplies the power generated by the power generation device 33 to the load 32 and supplies surplus power exceeding the power consumption of the load 32 to the power conditioner 20. The surplus power is converted into DC power by the inverter 21 through the self-sustained operation switch 24 in the power conditioner 20 and supplied to the storage battery 12.

  Note that the control unit 25 continuously monitors the current corresponding to the detected current in the first current sensor 40 even after the power generation device 33 starts power generation, so that the forward current is always detected. It is preferable to adjust the load 51. This is because when the power consumption in the load 32 or the generated power from the power generation device 33 varies, the power generation device 33 stops power generation when the first current sensor 40 detects a reverse power flow.

  In the present embodiment, the load 32 may be a pseudo load having a known load for determining the pseudo current in addition to various devices used by the user.

  In the present embodiment, as means for detecting the current flowing through the load 32, not only the second current sensor 70 alone but also a distribution board with a built-in current sensor may be used.

  In the present embodiment, the pseudo current is adjusted by adjusting the resistance value of the pseudo current load 51, but the present invention is not limited to this mode. The resistance value of the pseudo current load 51 may be fixed, and the voltage supplied to the pseudo output unit 50 may be adjustable.

  Further, in the present embodiment, the power supply to the pseudo output unit 50 is configured to be performed from the power conditioner 20, but is not limited to this mode. You may comprise so that electric power may be supplied to the pseudo output part 50 from the other power supply synchronized with the power conditioner 20. FIG.

  As described above, according to the present embodiment, the power control system 100 is configured such that the power generation device 33 and other distributed power sources (the solar battery 11 and the storage battery 12) are disconnected from the system. A pseudo output unit 50 that can supply power from the power source is provided, and a pseudo current that is a current in the same direction as the forward current can be supplied to the first current sensor 40 by the output from the pseudo output unit 50. This makes it possible to manage efficient operation control among a plurality of distributed power sources without destroying the versatility on the distributed power source side. More specifically, by generating a pseudo current through the first current sensor 40 during the self-sustained operation, the power generation device 33 can intentionally generate power. In addition, since the power generation of the power generation device 33 is controlled using the pseudo current to the first current sensor 40, there is no need to make any special changes to the power generation device 33 itself, and a general-purpose fuel cell system and gas power generation system are diverted. There is an advantage that you can.

  Further, according to the present embodiment, the synchronous switch 52 is a switch that synchronizes the switching / parallel switching with the system and the switching timing, and allows a pseudo current to flow at the time of disconnection and does not flow a pseudo current at the time of parallel. As a result, a pseudo current flows through the first current sensor 40 during the self-sustaining operation that is disconnected from the system. A pseudo current does not flow through the first current sensor 40 during the interconnected operation in parallel with the system, and a reverse power flow from the power generation device 33 does not occur by mistake.

  Further, according to the present embodiment, the self-sustained operation switch 24 is turned off at the time of the grid operation and turned on at the time of the self-sustained operation by the distributed power supply, and the Arranged between. As a result, the power generated by the power generation device 33 can be supplied to the other distributed power source through the self-sustained operation switch 24 during the self-sustaining operation.

  Further, according to the present embodiment, the storage battery 12 can be charged with electric power from the power generation device 33 when the self-sustaining operation switch 24 is turned on. Thereby, it is possible to store in the storage battery 12 surplus power that is generated by the power generation device 33 during the self-sustained operation and exceeds the power consumption of the load 32, for example.

  Further, in the present embodiment, a pseudo current determination mode is provided so that a pseudo current value necessary for causing the power generation apparatus 33 to start power generation is determined by measurement and can be adjusted to the determined value. With this configuration, since the pseudo current can be suppressed to a level necessary for the power generation device 33 to maintain the power generation state, unnecessary power consumption in the pseudo current load 51 can be suppressed.

  In this embodiment, the required pseudo current value is measured a plurality of times, and the average value or the minimum value is adopted. With this configuration, the pseudo current can be further suppressed, and unnecessary power consumption in the pseudo current load 51 can be further suppressed.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, functions included in each member, each means, each step, etc. can be rearranged so as not to be logically contradictory, and a plurality of means, steps, etc. can be combined or divided into one. Is possible.

DESCRIPTION OF SYMBOLS 11 Solar cell 12 Storage battery 13,14 DC / DC converter 20 Power conditioner (power control apparatus)
DESCRIPTION OF SYMBOLS 21 Inverter 22, 23 Interconnection operation switch 24 Self-supporting operation switch 25 Control part 26 Memory | storage part 31 Distribution board 32 Load 33 Electric power generation apparatus 40 1st current sensor 50 Pseudo output part 51 Pseudo current load 52 Synchronous switch 53 Pseudo current control switch 60 Transformer 70 Second current sensor 71 Third current sensor 100 Power control system

Claims (5)

While the first current sensor detects a forward current greater than or equal to the threshold value, a power generator that generates power according to the value detected by the first current sensor, and a power control that controls a distributed power source including the power generator A control method of a power control system comprising a device and a second current sensor that detects a current flowing through a load,
The first current sensor is disposed between the power control device and the power generation device,
The second current sensor is disposed between the power control device and the load;
The power control device is connected to a pseudo output unit capable of supplying a pseudo current that is a current in the same direction as a forward power flow to the first current sensor,
A first step of detecting a current value flowing through the load from at least one of a grid and the power control device as a first forward flow current value in a state where the pseudo current is stopped;
After the first step, when the current detected by the second current sensor increases, the value of the current flowing to the load from at least one of the system and the power control device increases, and then becomes a steady value. A second step of detecting the current value as a second forward current value;
And a third step of storing the second forward flow current value as the threshold value.   The control method of the power control system according to claim 1, wherein the second forward flow current value in the second step is measured a plurality of times, and the generated power of the power generator is set based on an average value thereof.   The power control system control method according to claim 1, wherein the second forward flow current value is a current value detected when the power generator follows the load. While the first current sensor detects a forward current greater than or equal to the threshold value, a power generator that generates power according to the value detected by the first current sensor, and a power control that controls a distributed power source including the power generator A power control system comprising a device and a second current sensor for detecting a current flowing through a load,
The first current sensor is disposed between the power control device and the power generation device,
The second current sensor is disposed between the power control device and the load;
The power control device is connected to a pseudo output unit capable of supplying a pseudo current that is a current in the same direction as a forward power flow to the first current sensor,
The power control device includes a control unit and a storage unit,
The control unit detects a current value flowing through the load from at least one of a system and the power control device as a first forward current value while the pseudo current is stopped,
After the detection of the first forward current value, when the current detected by the second current sensor increases, the value of the current flowing to the load increases from at least one of the system and the power control device. The current value when the steady value is reached is further detected as the second forward current value,
The power control system storing the second forward flow current value as the threshold in the storage unit. While the first current sensor detects a forward current greater than or equal to the threshold value, a power generator that generates power according to the value detected by the first current sensor, and a power control that controls a distributed power source including the power generator A device,
The first current sensor is disposed between the power control device and the power generation device,
A second current sensor for detecting a current flowing through the load is disposed between the power control device and the load;
The power control device is connected to a pseudo output unit capable of supplying a pseudo current that is a current in the same direction as a forward power flow to the first current sensor,
The power control device includes a control unit and a storage unit,
The control unit detects a current value flowing through the load from at least one of a system and the power control device as a first forward current value while the pseudo current is stopped,
After the detection of the first forward current value, when the current detected by the second current sensor increases, the value of the current flowing to the load increases from at least one of the system and the power control device. The current value when the steady value is reached is further detected as the second forward current value,
The power control device, wherein the second forward flow current value is stored in the storage unit as the threshold value.

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