JP6677665B2 - Power supply system and power supply system control method - Google Patents

Description

  The present invention relates to a power supply system and a control method of the power supply system.

  2. Description of the Related Art In recent years, in order to stabilize power supply, a hybrid power generation system including a plurality of power generation devices and a plurality of power conditioners for interconnecting power generated by the plurality of power generation devices to a power system has been widely used. Some power generation devices may not allow reverse power flow to the power system due to a contract with a power company. In such a power generation system, a current sensor is provided according to the number of power generation devices and power conditioners that cannot perform reverse power flow in order to detect reverse power flow of a power generation device that cannot perform reverse power flow (see Patent Document 1). .

JP 2012-95507 A

  In a combined power generation system, it is required to reduce the number of current sensors while detecting reverse power flows of a plurality of power generation devices. However, in a combined power generation system in which the number of current sensors is reduced, there is a possibility that output power of a plurality of power generation devices that do not allow reverse power flow is quickly changed, and that reverse power flow cannot be reduced quickly.

  Therefore, an object of the present invention is to reduce reverse power flow due to output power of a plurality of power generation devices that cannot reverse power flow.

  A power supply system according to a first aspect includes: a first power supply device disposed between a power system and a power load; a second power supply device disposed between the first power supply device and the power load; A signal control unit that controls a signal detected from a current sensor installed between a power system and the first power supply device. The first power supply device is configured such that the first power supply device supplies the power load to the power load in accordance with a relationship between a power value based on a first signal detected by the first power supply device from the current sensor and a predetermined reverse power flow threshold value. A first control unit that changes the first supply power to be supplied; The second power supply device may be configured to control the power load based on a relationship between a power value based on a second signal detected by the second power supply device from the current sensor and the predetermined reverse power flow threshold. A second control unit that changes the second supply power supplied to the power supply. The signal control unit controls so as to provide a predetermined offset between the first signal and the second signal.

  The control method of the power supply system according to the first aspect includes a first power supply device disposed between a power system and a power load, and a second power supply device disposed between the first power supply device and the power load. The present invention relates to a power supply system including a power supply device, and a signal control unit that controls a signal detected from a current sensor installed between the power system and the first power supply device. In the control method, the first power supply device supplies the power load to the power load according to a relationship between a power value based on a first signal detected by the first power supply device from the current sensor and a predetermined reverse power flow threshold value. Step A of changing the first supply power, and the second power supply device according to a relationship between a power value based on a second signal detected by the second power supply device from the current sensor and the predetermined reverse power flow threshold value Includes a step B of changing a second supply power supplied to the power load, and a step C of providing a predetermined offset between the first signal and the second signal.

  ADVANTAGE OF THE INVENTION According to the power supply system and the control method of the power supply system which concern on embodiment of this invention, the reverse power flow by the output electric power of the some power generation apparatus which cannot reverse power flow can be reduced.

FIG. 1 is a diagram illustrating a configuration of a power supply system according to an embodiment. FIG. 3 is a diagram illustrating a configuration for transmitting a signal detected by the current sensor according to the embodiment. FIG. 4 is a diagram illustrating an example of first power information in the power supply system according to the embodiment. FIG. 7 is a diagram illustrating a change in power when the signal control unit according to the present embodiment is a circuit that provides a time offset and when importance is placed on the efficiency of the power supply system. FIG. 7 is a diagram illustrating a change in power when the signal control unit according to the present embodiment is a circuit that provides a time offset and when the life of the power supply system is emphasized. FIG. 7 is a diagram illustrating a change in power when the signal control unit according to the embodiment is a circuit that provides a power offset and when importance is placed on the efficiency of the power supply system. FIG. 7 is a diagram illustrating a change in power when the signal control unit according to the embodiment is a circuit that provides a power offset and when the life of the power supply system is emphasized. FIG. 4 is a diagram illustrating an example of first power information in the power supply system according to the embodiment. It is a figure showing change of electric power when the current sensor concerning this embodiment does not detect reverse power flow. FIG. 4 is a diagram illustrating a method for rapidly reducing the supply power of the power supply device according to the embodiment. FIG. 4 is a diagram illustrating a method for determining power supply of the power supply device according to the embodiment. FIG. 6 is a diagram illustrating another configuration of the power supply system according to the embodiment.

(Configuration of power supply system)
Hereinafter, a power supply system according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a power supply system 100 is connected to a power system 200 and supplies power to a power load 300. In FIG. 1, solid lines connecting the functional blocks indicate power lines, and broken lines indicate control lines and signal lines. The connection indicated by the control line and the signal line may be a wired connection or a wireless connection.

  The power supply system 100 includes a first power supply device 20, a second power supply device 30, and a signal control unit 40. In the present embodiment, the first power supply device 20 and the second power supply device 30 are assumed to be fuel cells. Further, between the power system 200 and the first power supply device 20, a value of a current (forward power flow) flowing from the power system 200 to the power load 300 and a value of a current (reverse power flow) flowing from the power load 300 to the power system 200. Is installed. Note that the current sensor 400 is configured as, for example, a CT (Current Transformer). Further, in the present embodiment, the number of power supply devices is two, that is, the first power supply device 20 and the second power supply device 30. However, the number of power supply devices is not limited to this, and any number of power supply devices is possible. You may. In the present embodiment, the first power supply device 20 and the second power supply device 30 are fuel cells as examples. However, the power supply device is not limited to these, and may be a solar power generation device, a storage battery, or the like. Good.

  In the present embodiment, one of the plurality of power supplies included in the power supply system 100 is set as a master, and the other power supplies are set as slaves. In the present embodiment, as shown in FIG. 1, it is assumed that the first power supply 20 is set as a master and the second power supply 30 is set as a slave.

  The power load 300 is an electric device or the like installed in a customer facility. Power load 300 consumes power supplied from power supply system 100 or power system 200.

  The first power supply device 20 and the second power supply device 30 are connected to the current sensor 400 via the signal control unit 40, and acquire a signal related to a forward flow or a reverse flow from the current sensor 400.

  The first power supply device 20 includes a first power generation unit 21, a first auxiliary unit 22, a first power conversion unit 23, a first communication unit 24, a first storage unit 25, a first control unit 26, Is provided.

  The first power generation unit 21 generates an electrochemical reaction by the fuel supplied from the first auxiliary unit 22, and generates DC power. The first power generation unit 21 supplies the generated DC power to the first power conversion unit 23.

  The first auxiliary unit 22 is a peripheral device necessary for causing the first power generation unit 21 to generate power, and supplies fuel to the first power generation unit 21. The fuel is, for example, gas, air, reformed water or the like mixed at a predetermined ratio.

  The first power converter 23 converts DC power supplied from the first power generator 21 into AC power. The first power conversion unit 23 supplies the converted AC power to the power load 300.

  The first communication unit 24 communicates with the current sensor 400. Further, the first communication unit communicates with the second power supply device 30.

  The first storage unit 25 stores information necessary for processing of the first power supply device 20 and a program describing processing contents for realizing each function of the first power supply device 20.

  The first control unit 26 controls and manages the first power supply device 20 and the second power supply device 30, and is, for example, a processor.

  In addition, the first control unit 26 controls the first power supply device 20 to supply the first load to the power load 300 in accordance with the relationship between the power value based on the first signal detected from the current sensor 400 and a predetermined reverse power flow threshold value. Change the power supply.

The power value based on the first signal is a power value obtained by multiplying the flowing current value by the voltage on the power line at the power line at the position where the current sensor 400 is installed.
A power supply device such as a fuel cell in which reverse power flow to the power system 200 is not allowed is used to suppress reverse power flow to the power system 200 when the current sensor 400 detects reverse power flow to the power system 200. Therefore, it is necessary to reduce the first power supply to the power load 300. The first control unit 26 detects a power value based on the first signal from the current sensor 400. Then, when the power value falls below a predetermined reverse power flow threshold value (0 kW), first control unit 26 determines that power flows from first power supply device 20 to power system 200 in reverse power flow.

  Further, in the present embodiment, the predetermined reverse power flow threshold is 0 kW, but is not limited thereto. The first control unit 26 determines whether the current flowing through the power line on which the current sensor 400 is installed is a forward flow or a reverse flow. Therefore, the reverse power flow threshold may be any value as long as it can be a criterion for reducing the reverse power flow. For example, the reverse flow threshold may be a power value at which the reverse flow within 0.5 seconds is 5% or less of the rated output. This is because under the current Japanese system, reverse power flow is allowed within 5 seconds if the power value reaches 5% or less of the rated output. That is, the reverse power flow threshold can be set within a range in which reverse power flow is allowed.

  The second power supply device 30 includes a second power generation unit 31, a second auxiliary unit 32, a second power conversion unit 33, a second communication unit 34, a second storage unit 35, and a second control unit 36. Is provided.

  The second power generation unit 31 generates an electrochemical reaction by the fuel supplied from the second auxiliary unit 32 to generate DC power. The second power generation unit 31 supplies the generated DC power to the second power conversion unit 33.

  The second auxiliary unit 32 is a peripheral device necessary for causing the second power generation unit 31 to generate power, and supplies fuel to the second power generation unit 31. The fuel is, for example, gas, air, reformed water or the like mixed at a predetermined ratio.

  The second power converter 33 converts DC power supplied from the second power generator 31 into AC power. The second power conversion unit 33 supplies the converted AC power to the power load 300.

  The second communication unit 34 communicates with the current sensor 400. The second communication unit communicates with the first power supply device 20.

  The second storage unit 35 stores information necessary for processing of the second power supply device 30 and a program describing processing contents for realizing each function of the second power supply device 30.

  The second control unit 36 controls and manages the second power supply device 30, and is, for example, a processor. The second control unit 36 controls the second supply power supplied by the second power supply device 30 to the power load 300 in accordance with the relationship between the power value based on the second signal detected from the current sensor 400 and a predetermined reverse power flow threshold value. To change.

The power value based on the second signal is a power value obtained by multiplying the current flowing through the power line at the position where the current sensor 400 is installed by the voltage on the power line.
The second control unit 36 detects a power value based on the second signal from the current sensor 400. Then, when the power value falls below a predetermined reverse power flow threshold value (0 kW), second control unit 36 determines that power is flowing backward from second power supply device 30 to power system 200. In the present embodiment, by assuming that the predetermined reverse power flow threshold is 0 kW, the second control unit 36 determines whether the current flowing through the power line on which the current sensor 400 is installed is a forward power flow or a reverse power flow. However, the reverse power flow threshold is not limited to 0 kW, and may be any value as long as it is a criterion for suppressing reverse power flow. Further, in the present embodiment, a reverse power flow threshold, which is a criterion for determining a reverse power flow when the first control unit 26 changes the first supply power, and a reverse power flow when the second control unit 36 changes the second supply power. Although the reverse power flow threshold value, which is the criterion for determining the reverse power flow, is assumed to be 0 kW, the value may be different as long as it is a criterion for reducing the reverse power flow in the entire power supply system 100.

  Next, an operation in which the signal control unit 40 provides a predetermined offset will be described with reference to FIG.

  As shown in FIG. 2, the current sensor 400 detects a current flowing in a power line at a position where the current sensor 400 is installed, and causes a current to flow through the conducting wire so as to flow through the current measuring resistor 60.

  The differential amplifier 50 detects the power consumed by the current measurement resistor 60 based on the current flowing through the current measurement resistor 60 and the resistance value of the current measurement resistor 60. The differential amplifier 50 transmits the power consumed by the current measuring resistor 60 to the first controller 26 using a first signal. Further, the differential amplifier 50 transmits the voltage value of the current measuring resistor 60 to the second control unit 36 using a second signal.

  The first control unit 26 and the second control unit 36 can obtain the current flowing through the power line at the position where the current sensor 400 is installed from the known electric resistance value of the current measurement resistor 60. Then, first control unit 26 and second control unit 36 determine the forward flow and reverse flow between power system 200 and power load 300 based on the current and the voltage on the power line on which current sensor 400 is installed. To get as

  That is, the first control unit 26 acquires a power value based on the first signal detected from the current sensor 400, and the second control unit 36 acquires a power value based on the second signal detected from the current sensor 400. I do.

  As shown in FIG. 2, the signal control unit 40 is disposed between the branch point X of the signal path through which the first signal is transmitted and the branch point X of the signal path through which the second signal is transmitted, and the second power supply device 30. Is done. The signal control unit 40 controls the second signal detected by the second control unit 36 to provide a predetermined offset to the first signal detected by the first control unit 26. Note that, in the present embodiment, the signal control unit 40 is disposed at the above-described position, but is not limited thereto. The signal control unit 40 may be arranged, for example, between the first power supply device 20 and a branch point X of a signal path through which the first signal is transmitted and a signal path through which the second signal is transmitted. Further, if a predetermined offset can be provided between the first signal and the second signal, the signal control unit 40 can control a plurality of signal controls such as a signal control unit A and a signal control unit B that can set different offsets. The embodiment including the unit 40 may be employed. In this case, the signal control unit A may be disposed between the branch point X and the first power supply device 20, and the signal control unit B may be disposed between the branch point X and the second power supply device 30.

  The predetermined offset is, for example, a temporal offset or a power offset. Further, the predetermined offset may be an offset including both a temporal offset and a power offset.

  The temporal offset is, for example, a time on the order of 100 ms, but is not limited to this, and may be an arbitrary time as long as a temporal offset can be provided. The power offset is, for example, power of the order of several tens of watts, but is not limited thereto, and may be power of any order as long as a power offset can be provided.

  The signal control unit 40 is a circuit for providing a predetermined offset. The signal control unit 40 is, for example, a circuit such as an operational amplifier. The signal control unit 40 is not limited to the operational amplifier, and may be any signal control unit as long as a predetermined offset can be provided.

  The signal control unit 40 acquires the second signal, provides a predetermined offset, and outputs it.

  Normally, when the power supply system 100 does not include the signal control unit 40, when the power consumption of the power load 300 is rapidly reduced and the reverse power flow cannot be suppressed only by the rapid reduction of the power system 200, the first control unit 26 It is determined that the power value based on the first signal is lower than 0 kW. At this time, the second control unit 36 determines that the power value based on the second signal is lower than 0 kW. That is, both the first control unit 26 and the second control unit 36 determine that the supply power needs to be reduced. Accordingly, the first control unit 26 and the second control unit 36 individually control the supply power to be reduced, and thus the supply power may be reduced more than necessary. That is, there is a case where the control is performed such that the sum of the power supplied from the first control unit 26 and the second control unit 36 is lower than the power consumption of the power load 300. In such a case, it is difficult for the first control unit 26 and the second control unit 36 to efficiently adapt the supplied power to the power consumption of the power load 300.

  On the other hand, in the power supply system 100 according to the present embodiment, for example, the signal control unit controls the second signal detected by the second control unit 36 to be later than the first signal detected by the first control unit 26. When the current sensor 400 detects a reverse power flow, the timing at which the power value detected by the first control unit 26 falls below 0 kW and the timing at which the power value detected by the second control unit 36 falls below 0 kW Can be shifted. Thus, in the present embodiment, the timing at which the first supply power and the second supply power start to decrease can be shifted. Therefore, in the present embodiment, for example, control can be performed so as to reduce the output of the first supply power, and control can be performed without changing the output of the second supply power. Therefore, a decrease in the power consumption of the power load 300 is small. In this case, the first power supply device 20 and the second power supply device 30 can be efficiently controlled. As described above, in the present embodiment, the first supply power and the second supply power can be efficiently controlled, and thus the reverse power flow can be reduced quickly.

  Next, a specific control operation of the power supply system 100 will be described with reference to FIGS.

  In the drawings, a time offset is represented by T, and a power offset is represented by E.

  As shown in FIG. 3, a power supply system 100 that controls the first power supply device 20 as a master and the second power supply device 30 as a slave will be described. In the present embodiment, in a state before the execution of the control operation, the first power supply device 20 outputs the first supply power of the rated power (3 kW), and the second power supply device 30 outputs the second supply power of the rated power (3 kW). Is output. Further, it is assumed that the power consumption of power load 300 is 8 kW, and the forward flow from power system 200 is 2 kW. Hereinafter, the control operation of the first control unit 26 and the second control unit 36 when the power consumption of the power load 300 rapidly decreases from 8 kW to 4 kW in this state will be described. Further, the first signal detected by the first control unit 26 is a value of a forward flow from the power system 200 to the power load 300, and the second signal detected by the second control unit 36 is a signal control unit 40 Is the value of the forward flow from the power system 200 to the power load 300 at which the predetermined offset is provided.

  As shown in FIG. 4A, when the power consumption of the power load 300 sharply decreases from 8 kW to 4 kW, the power system 200 first reduces the forward power flow as much as possible so that the reverse power flow to the power system 200 does not occur. I do. In the present embodiment, 2 kW output from the power system 200 is reduced to 0 kW. At this time, when output control by the load following of the first power supply device 20 and the second power supply device 30 cannot be executed immediately, a small amount of power is reversely flown to the power system 200, so that the value of the forward power flow falls below 0 kW. There are cases. The first control unit 26 performs control to reduce the output of the first supply power by the remaining 2 kW when the value of the acquired forward power flow falls below 0 kW set as the reverse power flow threshold value. Specifically, as shown in FIG. 4A, the first supply power is changed from 3 kW to 1 kW.

  The signal control unit 40 provides a temporal offset so that the timing at which the second control unit 36 detects the forward flow is later than the timing at which the first control unit 26 detects the forward flow. As shown in FIG. 4 (B), the second control unit 36 controls the forward power flow delayed by a predetermined time from the time when the first control unit 26 detects the value of the forward power flow (hereinafter, referred to as a pseudo forward power flow). Is detected. The pseudo forward power flow does not fall below 0 kW due to the first supply power being reduced from 3 kW to 1 kW. Therefore, the second control unit 36 does not need to further reduce the supply power, and is in a state where the second supply power can be reduced, but can maintain the output without reduction.

  As described above, in the present embodiment, as shown in FIG. 4C, the first control unit 26 and the second control unit 36 determine the power value based on the first signal and the power value based on the second signal. When at least one of the above (power value based on the first signal in the present embodiment) falls below a predetermined reverse power flow threshold, at least one of the first supply power and the second supply power is controlled to be reduced. Make changes. Accordingly, even if the power consumption of the power load 300 is rapidly reduced, the first control unit 26 and the second control unit 36 may output the first supply power and the second supply power in descending order of priority in reducing the supply power. Since the power can be reduced, control can be performed such that the sum of the first supply power and the second supply power is substantially equal to the power consumption of the power load 300. As a result, in the present embodiment, the first supply power and the second supply power can be controlled efficiently, and thus the reverse power flow can be reduced quickly.

  Further, as shown in FIG. 4C, the signal control unit 40 controls the time so that the first supply power of the first power supply device 20 as the master can be reduced earlier than the second supply power. An offset may be provided. Thus, in the present embodiment, the control of the second power supply device 30 as the slave can be efficiently adapted to the control of the first power supply device 20 as the master.

  Further, as shown in FIG. 4C, the signal control unit 40 may provide a temporal offset so that the first supply power and the second supply power do not decrease at the same time. . Accordingly, a time period in which the sum of the first supply power and the second supply power is lower than the power consumption of the power load 300 can be shortened. As a result, in the present embodiment, when the supply power is restored after the total of the first supply power and the second supply power is reduced more than necessary, the total of the first supply power and the second supply power becomes the power load 300. It is possible to suppress the generation of the reverse power flow due to the power consumption or more.

  Next, a method for determining the first supply power and the second supply power after the first change will be described.

  As shown in FIG. 4C, the first changed values of the first supply power and the second supply power are 1 kW for the first supply power and 3 kW for the second supply power. Generally, in a power supply system having a plurality of fuel cells, when power generation efficiency is emphasized, the power generated by the plurality of fuel cells may be set to the rated power as much as possible. On the other hand, when it is important to extend the life of each fuel cell of the power supply system, the power generated by the plurality of fuel cells may be equalized as much as possible.

  When importance is placed on the efficiency of the power supply system 100, first, as shown in FIG. 4C, the first control unit 26 performs the first supply so that the first supply power as the master becomes the rated power of 3 kW. Determine the power. Further, the first control unit 26 performs the second control so that the second supply power, which is the slave, bears the remaining 1 kW obtained by subtracting 3 kW, which is the rated power of the first supply power, from 4 kW, which is the power consumption of the power load 300. Determine the power supply. In such control, the power supply set as the master (the first power supply device 20 in the present embodiment) can be operated at the rated power, so that the power generation efficiency can be improved.

  When the life of the power supply system 100 is emphasized, as shown in FIG. 5, the first control unit 26 acquires the power consumption of the power load 300 and, based on the acquired power consumption, obtains the first supply power and the second supply power. Are determined to be substantially equal. Specifically, the first control unit 26 controls the first supply power and the second supply power such that 4 kW, which is the power consumption of the power load 300, is equally allocated to the first supply power as 2 kW and the second supply power as 2 kW. Determine the power.

  The first control unit 26 transmits the determined values of the first supply power and the second supply power to the first communication unit 24. The first communication unit 24 transmits the obtained value to the second communication unit 34 by communication. The second control unit 36 acquires the value from the second communication unit 34. That is, the first control unit 26 and the second control unit 36 obtain final values of the first supply power and the second supply power.

  In the present embodiment, the power consumption (4 kW) of the power load 300 is smaller than the rated threshold value which is the total value (6 kW) of the respective rated powers of the first power supply device 20 and the second power supply device 30. Accordingly, the first control unit 26 and the second control unit 36 select and control which of the first mode in which the efficiency of the power supply system 100 is emphasized and the second mode in which the life is emphasized is preferentially executed. A second change can be made.

  As shown in FIG. 4C, in the first mode, for example, the first control unit 26, which is the master, outputs the first supply power preferentially, and the second control unit 36 supplies the second supply power to the power supply. In this mode, the remaining power obtained by subtracting the first supply power from the power consumption of the load 300 is output. In addition, the power supply device that outputs with priority may be the second power supply device 30. Accordingly, in the present embodiment, the first control unit 26 or the second control unit 36 selects a power supply device that has not deteriorated among the first power supply device 20 and the second power supply device 30 and outputs the power supply device with priority. By controlling, the life of the entire power supply system 100 can be extended. The first control unit 26 and the second control unit 36 may periodically collect information on the degree of deterioration of each power supply device and select a power supply device to output preferentially based on the information. Further, in the present embodiment, the first control unit 26 serving as the master determines the first supply power and the second supply power, but the second control unit 36 serving as the slave may perform the determination. Thereby, the first control unit 26 or the second control unit 36 periodically selects the power supply device that has not deteriorated among the first power supply device 20 and the second power supply device 30 so as to become the master. The life of the entire system 100 can be extended.

  On the other hand, as shown in FIG. 5, the second mode is, for example, a mode in which the first control unit 26 and the second control unit 36 make the first supply power and the second supply power approximately equal.

  Next, the first control unit 26 and the second control unit 36 execute the second change so that the first supply power and the second supply power become the determined values.

  At this time, the first control unit 26 and the second control unit 36 change the first supply power and the second supply power so that the reverse power flow to the power system 200 does not occur. Specifically, while the first control unit 26 increases the first supply power at the first speed, the second control unit 36 increases the second supply power at the second speed, which is the same speed as the first speed. To decrease. Thereby, the first control unit 26 and the second control unit 36 perform the second change while maintaining the total supply power of the first supply power and the second supply power substantially equal to the power consumption of the power load 300. Can be performed.

  As described above, in the present embodiment, the first control unit 26 and the second control unit 36 perform the operations based on the predetermined rated threshold (6 kW in the present embodiment) corresponding to the power load 300 and the rated power of the power supply system. A second change controlling the first supply power and the second supply power is performed. Thus, in the present embodiment, the priority operation in the power supply system 100 can be executed according to the value of the power consumption of the power load 300.

  Further, in the present embodiment, when the sum of the first supply power and the second supply power is equal to or less than a predetermined rated threshold, the first control unit 26 and the second control unit 36 A second change for controlling the sum of the supplied power and the power consumption of the power load 300 to be substantially equal is executed. Thereby, the first control unit 26 and the second control unit 36 can execute the priority operation in the power supply system 100 while suppressing the reverse power flow to the power system 200.

  Further, in the present embodiment, the predetermined offset is a temporal offset, but is not limited thereto and may be a power offset. The power offset will be described with reference to FIGS. The signal control unit 40 changes the power value (the power value of the pseudo forward power flow) based on the second signal detected by the second control unit 36 to the power value (forward) based on the first signal detected by the first control unit 26. A predetermined offset due to the power is provided so as to be larger by 2 kW than the power value of the power flow). Thus, similarly to the time offset, the timing at which the power value detected by the first control unit 26 falls below 0 kW and the timing at which the power value (pseudo forward power flow) detected by the second control unit 36 falls below 0 kW are shifted. be able to. Thus, in the present embodiment, the timing at which the first supply power and the second supply power start to decrease can be shifted.

  Next, an example in which the power consumption of the power load 300 is rapidly reduced from 8 kW to 6.4 kW as shown in FIG. 8 will be described. That is, this is a case where the power consumption of the power load 300 is higher than the rated power of the first power supply device 20 and the second power supply device 30.

  As shown in FIG. 9, the first control unit 26 and the second control unit 36 perform control so as not to change both the first supply power and the second supply power in the first change. Specifically, as shown in FIG. 9, when the power consumption of the power load 300 in the power supply system 100 to which the time offset is applied as the predetermined offset rapidly decreases from 8 kW to 6.4 kW, the power system 200 becomes In order to reduce the forward power flow as much as possible so that the reverse power flow does not occur, the power is reduced by 1.6 kW. The first control unit 26 and the second control unit 36 detect, as the first signal and the second signal, a change in the forward flow, that is, a decrease in the forward flow value from 2 kW to 0.4 kW.

  Since the power value based on the detected first signal is 0.4 kW and does not fall below 0 kW, the first control unit 26 controls the first control unit 26 so as not to reduce the first supply power. Accordingly, it is possible to cope with a sharp decrease in the power load 300 only by reducing only the forward flow from the power system 200. Also, the second control unit 36 does not need to reduce the second supply power, and thus controls the second supply power so as not to be reduced. As a result, the first supply power and the second supply power are substantially equal and have a rated output, so that the output efficiency of the power supply system 100 can be increased and the life can be further extended.

  In the present embodiment, when a solid oxide fuel cell (SOFC: Solid Oxide Fuel Cell) is applied as the fuel cell, it takes time to increase the output power. When the SOFC is used for the first power supply device 20 and the second power supply device 30, the first control unit 26 and the second control unit 36 determine the absolute value of the fluctuation speed of the first supply power and the second supply power by using the output of the SOFC. What is necessary is just to make it smaller than the increaseable speed.

  Specifically, the first control unit 26 determines a first speed at which the first supply power is increased so as to be smaller than the speed at which the output of the SOFC can be increased. The first control unit 26 transmits the determined speed to the second control unit 36. The second control unit 36 inverts the sign of the acquired first speed and determines a second speed at which the second supply power is changed. The first control unit changes the first supply power at the first speed, and the second control unit changes the second supply power at the second speed.

As described above, the first control unit 26 determines the first speed at which the first supply power is increased so as to be lower than the speed at which the output of the SOFC can be increased. The output of each power supply can be well controlled.
(Power supply system control method)

  Hereinafter, a control method of the power supply system 100 according to the embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 10, the signal control unit 40 determines a predetermined value between the power value based on the first signal detected by the first power supply device 20 and the power value based on the second signal detected by the second power supply system. Is provided (step S11). In the present embodiment, it is assumed that the predetermined offset is provided so that the first control unit 26 detects the first signal earlier than the second control unit 36 detects the second signal.

  Next, the first control unit 26 detects a first signal (Step S12). Note that step S12 is an operation after step 11, but step S12 may be an operation after step 11.

  The first control unit 26 determines whether the power value based on the first signal detected in step S12 is lower than 0 kW (step S13). When the power value based on the first signal from the current sensor 400 falls below 0 kW (step S13: Yes), the first control unit 26 determines that a reverse power flow occurs, and the first control unit 26 rapidly reduces the first supply power. A change step (step S14) is executed, and thereafter, the process proceeds to step 15. On the other hand, if the power value based on the first signal does not fall below 0 kW (step S13: No), it means that no reverse power flow from the first power supply device 20 and the second power supply device 30 to the power system 200 has occurred. . The first control unit 26 and the second control unit 36 control so that the first supply power and the second supply power become the rated output of each power supply device (step S18).

  Next, the second control unit 36 detects a second signal (Step S15). The second control unit 36 determines whether the power value based on the second signal detected in step S15 is lower than 0 kW (step S16). When the power value based on the second signal from the current sensor 400 falls below 0 kW (Step S16: Yes), the second control unit 36 determines that a reverse power flow occurs, and the second control unit 36 rapidly reduces the second supply power. The changing step (Step S17) is executed, and the process proceeds to the power supply determining process (Step S20).

  On the other hand, when the power value based on the second signal from the current sensor 400 does not fall below 0 kW (Step S16: No), the second control unit 36 determines that only the first supply power needs to be reduced, and The process proceeds to the power determination process (Step S20).

  Next, the supply power determination processing will be described with reference to FIG.

  Immediately before step S20, the first supply power and the second supply power have arbitrary values. At this time, the first control unit 26 and the second control unit 36 may change the first supply power and the second supply power depending on the situation in which the power supply system 100 is used. The power supply system 100 can execute control that gives priority to system efficiency or control that extends the life of the system. For example, in order to improve the efficiency of the power supply system 100 (supply power efficiency), it is necessary to output the power supply device at a rated value. On the other hand, in order to extend the life of the power supply system 100, it is necessary to make the output of each power supply device equal.

  Therefore, in the supply power determination process, it is determined whether the efficiency of the supply power is emphasized (step S21). When importance is placed on the efficiency of the power supply system 100 (Step S21: Yes), the first control unit 26 outputs the first supply power with priority (Step S22). As a result, the first control unit 26 controls the first supply power to be the rated output. On the other hand, when importance is attached to the life of the power supply system 100 (step S21: No), the first control unit 26 and the second control unit 36 make the first supply power and the second supply power substantially equal (step S23). .

  As described above, the control method of the power supply system 100 according to the present embodiment uses the first power supply device 20 based on the relationship between the power value based on the first signal detected from the current sensor 400 and the predetermined reverse power flow threshold value. Step A (step 14) in which the first power supply device 20 changes the first supply power supplied to the power load 300, and the power value based on the second signal detected by the second power supply device 30 from the current sensor 400 and a predetermined inverse value A step B (step 17) in which the second power supply device 30 changes the second supply power supplied to the power load 300 in accordance with the relationship with the power flow threshold value, and a predetermined signal between the first signal and the second signal. And C (step 11). This makes it possible to efficiently control the first supply power and the second supply power, so that the reverse power flow can be reduced quickly.

  Further, in the present embodiment, the control method of the power supply system 100 includes the steps A and B in which the power value based on the first signal and the power value based on the second signal are each lower than a predetermined reverse power flow threshold value. , A first change step (steps 14 and 17) of controlling at least one of the first supply power and the second supply power to be able to be reduced. Accordingly, even if the power consumption of the power load 300 is rapidly reduced, the first control unit 26 and the second control unit 36 may output the first supply power and the second supply power in descending order of priority in reducing the supply power. Since the power can be reduced, for example, control can be performed such that the sum of the first supply power and the second supply power is substantially equal to the power consumption of the power load 300 (step 23). Thus, the life of the power supply system can be extended.

Further, in the present embodiment, in the control method of the power supply system 100, the steps A and B control the first supply power and the second supply power based on the power consumption of the power load 300 and a predetermined rated threshold. A second change step (step S22) is included. Thereby, the first control unit 26 and the second control unit 36 can execute the priority operation in the power supply system 100 while suppressing the reverse power flow to the power system 200.
(Other embodiments)

  In the above-described embodiment, the first control unit 26 of the first power supply device 20 that is the master determines various items in the first power supply device 20 and the second power supply device 30 that is the slave, but is not limited thereto. Instead, it may be changed as appropriate.

  Further, the power supply system 100 shown in FIG. 2 has a configuration in which the signal control unit 40, the differential amplifier 50, and the current measuring resistor 60 are not included in the first power supply device 20 and the second power supply device 30. Not limited to For example, as shown in FIG. 12, the signal control unit 40, the differential amplifier 50, and the current measuring resistor 60 may be configured to be included in the first power supply device 20 and the second power supply device 30, respectively. In this case, by providing a changeover switch or the like on the signal path, the signal control unit 40 can provide a predetermined offset between the first signal and the second signal.

  Although the present invention has been described with reference to the drawings and embodiments, it should be noted that those skilled in the art can easily make various changes and modifications 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 component, each step, and the like can be rearranged so as not to be logically inconsistent, and a plurality of components, steps, and the like can be combined into one or divided. It is. Further, although the present invention has been described mainly with respect to the device, the present invention can be realized as a method, a program, or a storage medium storing the program, which is executed by a processor included in the device. Should be understood to include these. In this case, the storage medium may be a hard disk device, an optical disk, a CD-ROM, a CD-R, a memory card, a ROM, or the like.

REFERENCE SIGNS LIST 100 power supply system 200 power system 300 power load 400 current sensor 20 first power supply device 30 second power supply device 21 first power generation unit 22 first auxiliary unit 23 first power conversion unit 24 first communication unit 25 first storage unit 26 First control unit 31 Second power generation unit 32 Second auxiliary unit 33 Second power conversion unit 34 Second communication unit 35 Second storage unit 36 Second control unit 40 Signal control unit 50 Differential amplifier 60 Current measurement resistance T time Offset value E Power offset value

Claims (13)

A first power supply device disposed between the power system and the power load;
A second power supply disposed between the first power supply and the power load;
A signal control unit that controls a signal detected from a current sensor installed between the power system and the first power supply device,
The first power supply device is configured such that the first power supply device supplies the power load to the power load in accordance with a relationship between a power value based on a first signal detected by the first power supply device from the current sensor and a predetermined reverse power flow threshold value. A first control unit that changes a first supply power to be supplied,
The second power supply device may be configured to control the power load based on a relationship between a power value based on a second signal detected by the second power supply device from the current sensor and the predetermined reverse power flow threshold. A second control unit that changes the second supply power supplied to the
The power supply system, wherein the signal control unit controls so as to provide a predetermined offset between the first signal and the second signal.   The first control unit and the second control unit, when a power value based on the first signal and a power value based on the second signal respectively fall below the predetermined reverse power flow threshold, the first supply power and The power supply system according to claim 1, wherein a first change is performed to control at least one of the second supply power to be able to be reduced.   3. The power supply system according to claim 1, wherein the signal control unit is configured to provide the predetermined offset such that the first supply power can be reduced earlier than the second supply power. 4.   4. The power supply system according to claim 1, wherein the signal control unit sets the predetermined offset so that the first supply power and the second supply power do not decrease at the same time. 5.   The first control unit and the second control unit execute a second change that controls the first supply power and the second supply power based on power consumption of the power load and a predetermined rating threshold, The power supply system according to claim 1.   The first control unit and the second control unit, when a total of the first supply power and the second supply power is equal to or less than the predetermined rated threshold, the total is substantially equal to the power consumption of the power load. The power supply system according to claim 5, wherein the second change is performed so as to perform control. The first control unit and the second control unit, when the power consumption of the power load is less than the predetermined rated threshold,
Selecting a first mode in which the first supply power is output preferentially over the second supply power, and a second mode in which the first supply power and the second supply power are substantially equal. 7. The power supply system according to claim 6, wherein said second controlling step is performed.   The first control unit and the second control unit perform control such that when the power consumption of the power load is greater than the predetermined rated threshold, the first supply power and the second supply power become the rated power. The power supply system according to claim 6, wherein the second change is performed.   The power supply system according to claim 1, wherein the predetermined offset includes a temporal offset.   The power supply system according to claim 1, wherein the predetermined offset includes a power offset. A first power supply device disposed between the power system and the power load;
A second power supply disposed between the first power supply and the power load;
A signal control unit that controls a signal detected from a current sensor installed between the power system and the first power supply device,
The first power supply unit supplies a first supply power to the power load according to a relationship between a power value based on a first signal detected by the first power supply device from the current sensor and a predetermined reverse power flow threshold value. Step A to change;
A second supply power supplied by the second power supply to the power load according to a relationship between a power value based on a second signal detected by the second power supply from the current sensor and the predetermined reverse power flow threshold; Step B of changing
Providing a predetermined offset between the first signal and the second signal. C.   The step A and the step B are performed when the power value based on the first signal and the power value based on the second signal are respectively lower than the predetermined reverse power flow threshold value. The power supply system control method according to claim 11, further comprising a first changing step of controlling at least one of the electric powers to be able to be reduced. The method according to claim 12, wherein the step A and the step B include a second changing step of controlling the first supply power and the second supply power based on the power consumption of the power load and a predetermined rating threshold. The control method of the power supply system described in the above.

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