Power supply system and power management device

Abstract

To provide a power supply system that can control power in accordance with the dynamic characteristics of a power source.SOLUTION: A power supply system comprises multiple power supplies connected to each other in parallel, from which power is supplied to a load. Each of the multiple power supplies comprises a power source and a power supply circuit. The power supply circuit 500 comprises: a drooping characteristic calculation unit 210 for calculating a voltage command value so that an output voltage should droop with respect to an output power outputted by the power supply at a prescribed droop rate; and a ramp rate control unit 510 for correcting the voltage command value so that the amount of change of the output voltage should be suppressed when the amount of change per unit time of the output power surpasses a prescribed ramp rate. The ramp rate is differently set according to the type of a power source for each of the power supplies.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a power supply system that supplies power to a load and power management device to and.

Background Art

[0002] Patent Document 1 discloses a fuel cell system in which a fuel cell and a storage battery (secondary battery) are connected in parallel to supply power to a load (motor). The voltage of the fuel cell is monitored, and when a sudden load fluctuation occurs, the deterioration of the fuel cell is prevented by restricting an increase in the output of the fuel cell to follow the load fluctuation. The shortage due to this restriction is calculated in advance from the load information, a command is given to the DC / DC converter, and the shortage is compensated by the output power from the storage battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the fuel cell system of Patent Document 1, the fuel cell is directly connected to the load, and the output power from the fuel cell cannot be autonomously changed. For this reason, the control unit calculates the difference between the load power and the power from the fuel cell, and operates the power supply circuit (DC / DC converter) connected to the storage battery so as to compensate for the difference. In order to calculate the command value of this power difference (shortage), load fluctuation prediction information is required. For this reason, in the system disclosed in Patent Document 1, it is required that the relationship between the power supply and the load is closely fixed, such as in a fuel cell system mounted on a vehicle.

[0005] Furthermore, there is no problem if the load power changes as predicted by the fluctuation prediction information. However, in reality, when the vehicle body slips or encounters resistance such as a headwind, there may be a difference between the predicted load fluctuation and the actual power required. In such a case, the discrepancy between the battery command and the actual load power will be compensated by the power from the fuel cell, imposing a burden on the fuel cell.

[0006] Towards the realization of a low-carbon society, there has been an active movement to incorporate power generators and batteries using hydrogen as fuel into the power supply. On the other hand, the proposal and adoption of power supply configurations independent of conventional power systems such as thermal power generation using fossil fuels have become active in response to the low-carbon movement. Examples include trains using polymer electrolyte fuel cells (PEFC) and microgrid applications using solid oxide fuel cells (SOFC) among hydrogen fuel cells.

[0007] Figures 1A and 1B are examples of a power supply system that includes a plurality of power sources and supplies power to a load. Figure 1A is a power supply system connected to the grid like a renewable energy site, and Figure 1B is a power supply system that independently supplies power to a load like a moving body such as a vehicle. Since the battery 20 and the fuel cell 30 each generate a DC voltage, when connected to the grid 50 (Figure 1A), they are connected to the load 10 via a PCS (Power Conditioning System) 40, convert the DC power into AC power, and then supply it to the load 10. In Figure 1B, since the battery 20 and the fuel cell 30 only need to supply DC power to the load 11, they are connected to the load 11 via a DC / DC converter 60. The PCS 40 or the DC / DC converter plays a role in controlling the amount of power supplied by each power source according to the load power used by the load.

[0008] When supplying power from a plurality of power sources to a common load as shown in FIGS. 1A and 1B, it is necessary to adjust the power distribution between the power sources. In an environment such as a microgrid where an unspecified number of loads and power sources are expected to be connected or disconnected, a control mechanism for controlling the supplied power for each power source as in Patent Document 1 cannot be provided. Even in such a case, in order to autonomously share the load among the power sources connected in parallel and operate them, a technique of operating each power source with a droop characteristic is known.

[0009] FIG. 2A shows a block diagram of a DC / DC converter with a droop characteristic added (hereinafter referred to as a droop control DC power supply circuit). The droop control DC power supply circuit 200 has a voltage control DC / DC converter 220 and a droop characteristic calculation unit 210.

[0010] The voltage control DC / DC converter (output voltage control unit) 220 has a DC / DC converter 223 in the narrow sense, a voltage feedback (FB) control unit 222, and a voltage sensor 221 that measures the output voltage V from the DC / DC converter 223. The DC / DC converter 223 controls the ratio of the input voltage V I to the output voltage V. The voltage FB control unit 222 compares the voltage command value V S from the droop characteristic calculation unit 210 with the feedback voltage V F from the output, and issues a voltage ratio command to the DC / DC converter 223 so that the difference between the two becomes zero. As a result, the output voltage V operates to match the voltage command value V S .

[0011] On the other hand, the rated value V0 and the droop rate k of the power source are set in advance in the droop characteristic calculation unit 210. The droop characteristic calculation unit 216 calculates a voltage value obtained by subtracting the product of the droop rate k and the power P output by the DC / DC converter 223 from the rated value V0, and inputs it as the voltage command value V S to the voltage control DC / DC converter 220. Here, the power P is the input current I I measured by the current sensor 211 on the input side of the DC / DC converter 223, and the input voltage V IAlthough it is calculated by the power calculation unit 213 using [specific method], it may also be calculated using the current value and voltage value on the output side.

[0012] The operating point when a load is connected to this droop power supply is shown in FIG. 2B. Hereinafter, in the following, a power source such as a generator or a battery that generates power, to which a power supply circuit that controls power supply to a load is connected, is called a power supply. When the power supply circuit of the power supply has a droop characteristic, it may also be called a droop power supply. The droop power supply has a characteristic straight line 231 that droops the output voltage V in proportion to the output power P. On the other hand, the load (if it is a resistor) has a load straight line 232 whose voltage increases according to the power P. The point where these intersect becomes the operating point 233. When the load is connected to the power supply, it automatically moves to this operating point.

[0013] FIG. 3A shows a power supply system in which a plurality of droop power supplies A and B are connected in parallel to supply power to a load 11. The power supply A uses a storage battery 20 as a power source, and the power supply B uses a fuel cell 30 as a power source. In this case, as shown in FIG. 3B, the voltage droops according to the power supply to the load from each power supply, and balances where the output voltages of each power supply match. In this example, the power from the power supply A is power P 1A and the power from the power supply B is power P 1B and they balance at this point. In addition, in order to change the power sharing between the power supplies, different slopes of the straight lines, that is, droop rates k, may be set.

[0014] Furthermore, it is assumed that the load straight line of the load 11, which was the load straight line shown in FIG. 3B at time t1, changes to the load straight line shown in FIG. 3C at time t2. In accordance with this change in the load, the output voltages of each power supply move to the operating point where they balance. In this example, the power from the power supply A is power P 2A and the power from the power supply B is power P 2B and they balance at this point. In this example, since the power sharing ratio between the power supplies is made equal, the power from each power supply is always equal even if the load straight line moves.

[0015] FIG. 4 shows the time variations 401A and 401B of the output power distributed to power supplies A and B in accordance with the time variation 400 of the load power. If each power supply is the power supply of FIG. 3A, the same time variation is shown between power supply A and power supply B so as to equally distribute the load. Therefore, even during a sudden change 403 such as when the load power rapidly increases, both power supplies will accept half of the rapidly changing power each.

[0016] However, when a fuel cell is used as the power source, since power generation is performed based on fuel supply, it is often unable to cope with a steep change in the load. That is, since the fuel supply system is mechanical, it is one to two orders of magnitude slower than the electrical response. When the fuel supply does not match the required increase in output power, fuel shortage or excess occurs in the battery, and there is a risk of significantly deteriorating the battery cells even for a short time.

[0017] From the above, in a power supply system in which droop power supplies are connected in parallel, by determining the sharing ratio in advance according to the capacity of each power supply between the power supplies, the power supply to the load can be autonomously controlled. That is, power control according to the static characteristics of each power supply and load is possible. On the other hand, as explained in FIG. 4, if the power change in each power supply in response to a rapid change in load power is also determined by the sharing ratio determined by its static characteristics, there is a risk of deteriorating a power source that is difficult to respond to rapid power fluctuations, such as a fuel cell.

[0018] Therefore, the present invention provides a power supply system capable of power control in accordance with the dynamic characteristics of the power source. In a power supply system that supplies power to a load by combining a plurality of power sources with different temporal response characteristics of the output power, such as a fuel cell and a storage battery, as power sources in a microgrid or a mobile body, not only the steady power distribution (sharing) according to the conditions of each power source, but also the increase and decrease rate during a sudden change in the load power can be changed and controlled.

Means for Solving the Problem

[0019] A power supply system according to an embodiment of the present invention is a power supply system that supplies power to a load, and includes a first power supply including a first power source and a power supply circuit, and a second power supply that is connected in parallel with the first power supply and includes a second power source of a different type from the first power source and a power supply circuit, and a power supply management device. Power is supplied from the first power supply and the second power supply to the load. The power supply circuits included in the first power supply and the second power supply each include an output voltage control unit that controls the output voltage output from the power supply based on a voltage command value, a droop characteristic calculation unit that calculates a voltage command value so that the output voltage droops at a predetermined droop rate with respect to the output power output from the power supply, and a ramp rate control unit that corrects the voltage command value so as to suppress the change amount of the output voltage when the change amount of the output power per unit time exceeds a predetermined ramp rate. The power supply management device sets a ramp rate for each of the first power supply and the second power supply, and makes the ramp rate set for the first power supply different from the ramp rate set for the second power supply.

Advantages of the Invention

[0020] Provided is a power supply system capable of power control in accordance with the dynamic characteristics of a power source. Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Brief Description of the Drawings

[0021]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3A

Figure 3B

Figure 3C

Figure 4

Figure 5A

Figure 5B

Figure 6A

Figure 6B

Figure 6C

Figure 7

Figure 8

Figure 9A

Figure 9B

Figure 9C

Figure 9D

Figure 10A

Figure 10B

Figure 10C

Figure 10D

Figure 10E

Figure 11

Figure 12A

Figure 12B

Figure 13

Figure 14A

Figure 14B

Figure 15

Figure 16A

Figure 16B

Mode for Carrying Out the Invention

Examples

[0022] Fig. 5A shows the configuration of the power supply circuit in this embodiment. A lamp rate control unit 510 capable of setting the lamp rate from the outside is added to the droop control DC power supply circuit shown in Fig. 2A. For the configuration common to Fig. 2A, the same reference numerals are used, and duplicate descriptions are omitted.

[0023] In the corrected droop control DC power supply circuit 500 of this embodiment, a corrected voltage command value V S obtained by adding a voltage correction value V M determined by the lamp rate control unit 510 to the voltage command value V output from the droop characteristic calculation unit 210 is input to the voltage control DC / DC converter 220. When the power value P input from the power calculation unit 213 changes steeply, the lamp rate control unit 510 corrects the voltage command value V MS with the voltage correction value V S based on a lamp rate which is a temporal slope r (=ΔP / Δt). M

[0024] The definition of the lamp rate r will be described with reference to Fig. 5B. The lamp rate r is generally defined as the power change ΔP over a certain time interval (t2 - t1). In this example, the maximum power difference ΔP MAX ​Define the ramp rate. When defining the ramp rate separately for the power increase and decrease, the maximum power difference ΔP corresponding to the ramp rate r during the increase is + and the maximum power difference ΔP corresponding to the ramp rate r during the decrease is MAX+ Let it be. - MAX-

[0025] The operation of the ramp rate control unit 510 will be described using the flowcharts of FIGS. 6A to 6C. This flowchart shows the operation of the ramp rate control unit 510 when the load is increasing. FIG. 6A is the initialization flow. Initialize the voltage correction value V to 0, and calculate the maximum power difference ΔP from the ramp rate r during the increase set in the power supply system and the unique sampling interval Δt. Also, FIG. 6B is the reset flow executed when the ramp rate r during the increase in the power supply system is reset. Note that examples of resetting the ramp rate will be described later as Examples 3 and 4. In accordance with the setting change, recalculate the maximum power difference ΔP. M + MAX+ + MAX+

[0026] FIG. 6C is the voltage correction value calculation flow, and the voltage correction value V is calculated using the maximum power difference ΔP calculated in the initialization flow or the reset flow. The voltage correction value calculation flow is activated at every time interval of Δt, and the power value P is acquired from the power calculation unit 213 (S01). Calculate the difference ΔP (=P - P') from the previous acquired power value P' stored in the ramp rate control unit 510 (S02). Then, update the previous acquired power value P' to the currently acquired power value P (S03). Compare the difference value ΔP with the set maximum power difference ΔP. If the difference value ΔP is greater than or equal to ΔP, output the voltage correction value V so as to eliminate it, that is, without voltage correction following ΔP (S05). An example of the correction formula for the voltage correction value V at this time is shown in (Equation 1). MAX+ M MAX+ MAX+ M M V M →V M ​​​​​​​​​​​​​-k×(ΔP - ΔP MAX+ ) (Equation 1) Here, k is the droop rate of the droop characteristic calculation unit 210, and the symbol "→" means update, indicating that each correction is performed cumulatively.

[0027] On the other hand, when the difference value ΔP is lower than ΔP MAX+ (yes in step S04) and the voltage correction value V M is 0 (no in step S06), the correction of the voltage command value V S is not performed (voltage correction value V M = 0). Or, when the difference value ΔP is lower than ΔP MAX+ (yes in step S04) and power correction has already been performed and the voltage correction value V M is negative (yes in step S06), the voltage correction value V M is updated to be reset to 0 (S07). V M →V M +k×(ΔP MAX+ - ΔP) (Equation 2) (Equation 2) is an example of the correction formula for the voltage correction value V M .

[0028] A power supply system in which correction droop power supplies A and B equipped with the correction droop control power circuit described above are connected in parallel in the same manner as in FIG. 3A is shown in FIG. 7. Hereinafter, an example in which the droop rate k is made equal so that the load power is equally divided between power supplies A and B is shown, but to change the balance, the droop rates k of the two power supplies may be made different.

[0029] In the power supply system of FIG. 7, the time-series change when the same ramp rates r A+ and r B+ are set for the two power supplies will be described. When the increment ΔP of the load power per unit time Δt changes beyond the sum of the ramp rates of the two power supplies (=r A+ + r B+ ), the correction of the voltage command value V S is performed. FIG. 8 shows the power P A , P B output by power supplies A and B when the load power changes from power P1 to P2.is the time series change. The powers output by power supplies A and B when the load power is P1 are P 1A , P 1B respectively, and the powers output by power supplies A and B when the load power is P2 are P 2A , P 2B respectively, as shown. In this case, since the power command values of power supplies A and B are corrected by the same voltage correction value V M , they will show the same droop characteristics as power supplies A and B, and the power will also change equally. The change in the operating point on the droop characteristic accompanying the change in the load line is the same as that in FIGS. 3A and 3B.

[0030] In contrast, regarding the time series change when different ramp rates r A+ and r B+ (r A+ >r B+ ) are set for the two power supplies, it will be described with reference to FIGS. 9A to 9D. FIG. 9A is the time series change of the powers P A , P B output by power supplies A and B when the load power changes from P1 to P2. FIGS. 9B to 9D show the change in the operating point on the droop characteristic accompanying the change in the load line.

[0031] FIG. 9B shows the operating points of power supplies A and B at time t1 in FIG. 9A. For the load power P1, when the power from power supply A is power P 1A and the power from power supply B is power P 1B , they are balanced. In this state, the load line moves from Load1 to Load2. From time t1 to t2, when the ramp rate r B+ of power supply B is smaller than the power increment of the load, the power change of power supply B is more restricted and changes gently compared to power supply A. That is, the characteristic line showing the droop characteristic of power supply B is corrected downward, and the power share of power supply B is temporarily reduced compared to power supply A. From time t2 to t3, when the power change of the load becomes small (in this case, disappears), the voltage correction value V M at power supply B returns to 0. That is, the characteristic line of power supply B returns to the original state.

[0032] This state is shown in FIG. 9C. From time t1 to t3, the ramp rate r of power supply A A+ is greater than the power increment of the load, and the ramp rate r of power supply B B+ is less than the power increment of the load. In this case, the characteristic line 901 of power supply A does not change, but the characteristic line of power supply B is corrected downward from the characteristic line 902 at time t1 to the characteristic line 903. As a result, the power borne by power supply A is power P 2A , and the power borne by power supply B is power P 2B , and power P 2A > power P 2B .

[0033] FIG. 9D shows the operating points of power supplies A and B at time t3 in FIG. 9A. At this time, the characteristic line of power supply B returns to the original state, and for the load power P2, the power from power supply A is power P 2A , and the power from power supply B is power P 2B , and they balance.

[0034] Even when the load power decreases, the power distribution between the power supplies can be automatically changed at the time of a sudden change in the load power using the falling ramp rate r - . The definition of the falling ramp rate r - is shown in FIG. 10A. By setting the falling ramp rate r - , the correction droop control DC power supply circuit 500 can change the power distribution between the power supplies even at the time of a sudden change in the downward direction of the load power by the same flow. For the time series change when different ramp rates r A- and r B- (let r A- > r B- ) are set for the two power supplies, FIGS. 10B to E are used for explanation. FIG. 10B shows the time series change of the power P A , P B output by power supplies A and B when the load power changes from power P2 to P1. FIGS. 10C to E show the change of the operating point on the droop characteristic accompanying the change of the load line.

[0035] Figure 10C shows the operating points of power supplies A and B at time t1 in Figure 10B. In this state, the load line moves from Load1 to Load2. Figure 10D shows the operating points of power supplies A and B from time t1 to t3. From time t1 to t3, the ramp rate r A+ of power supply A is greater than the power reduction of the load, and the ramp rate r B+ of power supply B is smaller than the power reduction of the load. In this case, the characteristic line 1001 of power supply A does not change, but the characteristic line of power supply B is corrected upward from the characteristic line 1002 at time t1 to the characteristic line 1003. As a result, the power borne by power supply A is power P 2A , and the power borne by power supply B is power P 2B , and power P 2B > power P 2A . It can be seen that in this way, the amount of power reduction borne by power supply A is larger than that of power supply B, and power supply A bears most of the fluctuations. Figure 10E shows the operating points of power supplies A and B at time t3. At this time, the characteristic line of power supply B has returned to its original state.

[0036] In this way, by setting different ramp rates for each power supply, it becomes possible to differentiate and allocate the amount of power change for each power supply during sudden load changes. In particular, the differentiated allocation can be automatically performed without sequentially commanding from the outside.

Example

[0037] A power supply system using the power supply described in Example 1 will be described. The power supply system in FIG. 11 has a power management device 1100 that manages the power supply system, and the power management device 1100 includes a lamp rate setting unit 1101 that sets the lamp rate of each power supply. The lamp rate is determined by the list of power supplies to be connected. For the same type of power supply, the same lamp rate may be used, but for power supplies with different response characteristics, different lamp rates are set. For example, when there are three types of power supplies, a supercapacitor (SC), a lithium-ion battery (LIB), and a fuel cell (FC), different lamp rates are set according to the response characteristics. As a result, when the load 11 fluctuates, the fluctuations can be absorbed in the order of the power supplies with higher lamp rates. However, the sum of the lamp rates of each power supply should be the lamp rate t of the load LOAD It is necessary to set it as above. The sum of the lamp rates of each power supply is the lamp rate t of the load LOAD If it is less than this, the power supply system cannot follow the power change of the load 11, which is why this situation occurs.

[0038] FIG. 12A shows a lamp rate setting table 1200 held by the lamp rate setting unit 1101. The power supplies are classified into ranks according to their response characteristics, and the rising lamp rate r + and the falling lamp rate r - are set for each rank. The response characteristics of the three types of power supplies described above are SC >LIB >>FC Therefore, it is assumed that SC is classified into rank A, LIB is classified into rank B, and FC is classified into rank C. Note that the types of power sources shown here are just examples and do not limit that the power supply system has all the types of power sources exemplified.

[0039] A flowchart of the power supply update executed by the lamp rate setting unit 1101 is shown in FIG. 12B. This flow is activated when there is a change in the configuration of the power supplies in the power supply system (S11). Refer to the lamp rate setting table 1200 and set the lamp rate according to the rank of the added power supply (S12 to S17).

Example

[0040] In the power supply system of FIG. 13, a ramp rate adjustment unit 1301 that adjusts the ramp rate is provided for a power supply (hereinafter referred to as a fuel cell power supply) in which a power management device 1100 uses a fuel cell as a power source. When the load power fluctuates (especially when increasing), the fuel supply to the fuel cell may not catch up, fuel shortage may occur in the cell, and the voltage of the cell constituting the fuel cell 30 may decrease. This situation deteriorates the cell. To prevent such deterioration, while monitoring the cell voltage of the fuel cell 30, the ramp rate of the fuel cell power supply is adjusted so as not to exceed the threshold value to protect the fuel cell.

[0041] The fuel cell power supply has a minimum cell voltage calculation unit 1302. The minimum cell voltage calculation unit 1302 monitors the output voltage of the cell group constituting the fuel cell 30, and notifies the output voltage value Vcell of the cell that generates the minimum voltage to the ramp rate adjustment unit 1301 of the power management device 1100.

[0042] FIG. 14A shows a setting table 1400 held by the ramp rate adjustment unit 1301. The cell voltage threshold value of the cell voltage Vcell notified from the minimum cell voltage calculation unit 1302 and the correction width Δr of the ramp rate to be adjusted when the threshold value is exceeded are set.

[0043] A flowchart of the ramp rate adjustment executed by the ramp rate adjustment unit 1301 is shown in FIG. 14B. As a premise, as described in the second embodiment, a predetermined ramp rate is set for the fuel cell power supply. The ramp rate adjustment unit 1301 always monitors the output power P from the fuel cell 30 (S21 to S25), and when there is a change in the output power (yes in step S25), the cell voltage Vcell is evaluated with reference to the setting table 1400. In a state where the load power is increasing, when the cell voltage Vcell becomes smaller than the lower limit value Vcellmin, even if the ramp rate setting of the fuel cell power supply is rank C, the fuel supply cannot catch up with the change in the load power, and it is assumed that the fuel is lacking. Therefore, the rising ramp rate r of the fuel cell power supply + is set to the correction width Δr defined in the setting table 1400 +Notify the fuel cell power supply to correct it so as to only reduce it, thereby suppressing an increase in power from the fuel cell power supply (S26 - S27).

[0044] Also, when the load power is decreasing and the cell voltage Vcell is not less than the upper limit value Vcellmax, there may be a possibility of fuel excess. Therefore, when the ramp rate r - is corrected to be reduced by the correction width Δr - specified in the setting table 1400, notify the fuel cell power supply to correct it so as to only reduce it, thereby suppressing a decrease in power from the fuel cell power supply (S28 - S29).

[0045] When the load is not fluctuating (no in step S25), notify the fuel cell power supply to return the ramp rate to its original value (S30).

[0046] As described above, even after setting the ramp rate according to the fuel cell power supply, by monitoring the cell voltage of the fuel cell and correcting the ramp rate so as not to exceed the allowable value, deterioration of the fuel cell can be prevented.

Example

[0047] In the power supply system of FIG. 15, the power management device 1100 includes a ramp rate adjustment unit 1501 that adjusts the ramp rate for the fuel cell power supply. The ramp rate adjustment unit 1501 monitors the fuel flow rate F of the fuel supply system 1502 that supplies fuel to the fuel cell 30, and when the flow rate cannot catch up with the increase in the output of the fuel cell power supply, adjusts the ramp rate of the fuel cell power supply to protect the fuel cell. Specifically, it monitors the fuel flow rate F, and when the rate of change of the flow rate (increase rate) does not exceed the increase rate of the output power, it adjusts the ramp rate of the fuel cell power supply to protect the fuel cell.

[0048] The fuel supply system 1502 of the fuel cell power supply supplies fuel to the fuel cell 30 and notifies the ramp rate adjustment unit 1501 of the power management device 1100 of the fuel flow rate F.

[0049] Fig. 16A shows a setting table 1600 held by the lamp rate adjustment unit 1501. A threshold value of the ratio of the output voltage change rate to the flow rate change rate (hereinafter referred to as the change rate ratio ΔP / |ΔF|) and a correction width Δr of the lamp rate to be adjusted when the threshold value is exceeded are set.

[0050] A flowchart of the lamp rate adjustment executed by the lamp rate adjustment unit 1501 is shown in Fig. 16B. As a premise, as described in the second embodiment, a predetermined lamp rate is set for the fuel cell power supply. The lamp rate adjustment unit 1501 always monitors the output power P and the fuel flow rate F from the fuel cell 30 (S41~S45). When there is a change in the output power (yes in step S45), the change rate ratio ΔP / |ΔF| is evaluated with reference to the setting table 1600. In a state where the load power is increasing, when the change rate ratio ΔP / |ΔF| exceeds the upper limit value 1, it is assumed that the fuel supply cannot catch up with the change in the load power and the fuel is lacking. Therefore, when the fuel cell power supply rises, the lamp rate r + is corrected to be reduced by the correction width Δr - specified in the setting table 1600, and by notifying the fuel cell power supply, the increase in power from the fuel cell power supply is suppressed (S46~S47).

[0051] Also, in a state where the load power is decreasing, when the change rate ratio ΔP / |ΔF| is below the lower limit value -1, there may be an overabundance of fuel. Therefore, when the fuel cell power supply drops, the lamp rate r - is corrected to be reduced by the correction width Δr - specified in the setting table 1600, and by notifying the fuel cell power supply, the decrease in power from the fuel cell power supply is suppressed (S48~S49).

[0052] When the load is not fluctuating (no in step S45), the fuel cell power supply is notified to return the lamp rate to its original value (S50).

[0053] As described above, even after setting the ramp rate according to the fuel cell power supply, by monitoring the change rate ratio ΔP / |ΔF| of the fuel cell and correcting the ramp rate so as not to exceed the allowable value, deterioration of the fuel cell can be prevented.

[0054] As described above, the present invention has been described using examples. In the above examples, a power supply system that supplies DC power to a load has been described, but the same applies to a power supply system that supplies AC power to a load. In this case, similar effects can be obtained by similarly controlling the effective voltage of the AC voltage output by the PCS.

[0055] Also, in a parallel load system in which a plurality of loads are connected in parallel to one power supply, different droop characteristic control and ramp rate control may be applied to the power supply circuit for each load. It can be easily inferred that the same effect can be obtained as in the embodiment except that the direction of power is reversed. In this case, by making the ramp rate for a specific load, for example, a water electrolyzer, smaller than that for other loads, rapid power fluctuations can be suppressed and electrolyzer deterioration can be prevented.

Description of Reference Numerals

[0056] 10, 11: Load, 20: Storage battery, 30: Fuel cell, 40: PCS, 50: System, 60: DC / DC converter, 200: Droop control DC power supply circuit, 210: Droop characteristic calculation unit, 211: Current sensor, 212, 221: Voltage sensor, 213: Power calculation unit, 216: Droop characteristic calculation unit, 220: Voltage control DC / DC converter, 222: Voltage feedback control unit, 223: DC / DC converter, 231: Characteristic straight line, 232: Load straight line, 233: Operating point, 500: Correction droop control DC power supply circuit, 510: Ramp rate control unit, 1100: Power management device, 1101: Ramp rate setting unit, 1200: Ramp rate setting table, 1301: Ramp rate adjustment unit, 1302: Minimum cell voltage calculation unit, 1400: Setting table, 1501: Ramp rate adjustment unit, 1502: Fuel supply system, 1600: Setting table.

Claims

1. In a power supply system that supplies power to a load, a first power supply including a first power source and a power supply circuit; a second power supply connected in parallel with the first power supply and including a second power source of a different type from the first power source and a power supply circuit; and a power management device, power is supplied to the load from the first power supply and the second power supply, the power supply circuits included in the first power supply and the second power supply each include an output voltage control unit that controls an output voltage output by the power supply based on a voltage command value, a droop characteristic calculation unit that calculates the voltage command value so that the output voltage droops at a predetermined droop rate with respect to the output power output by the power supply, and a ramp rate control unit that corrects the voltage command value to suppress a change amount of the output voltage when a change amount of the output power per unit time exceeds a predetermined ramp rate, the power management device sets a ramp rate for each of the first power supply and the second power supply, and makes the ramp rate set for the first power supply different from the ramp rate set for the second power supply, the first power supply is a power supply using a fuel cell as a power source, the first power supply includes a minimum cell voltage calculation unit that monitors an output voltage of a battery cell group constituting the fuel cell and notifies the power management device of a cell voltage value that is an output voltage value of a battery cell that generates a minimum output voltage, the power management device includes a ramp rate adjustment unit that is notified of an output voltage value and the cell voltage value of the first power supply from the first power supply, the ramp rate adjustment unit re-sets the ramp rate set for the first power supply to decrease by a predetermined width when a change is observed in the output voltage value of the first power supply and the cell voltage value exceeds a predetermined cell voltage threshold, and notifies the first power supply of the re-set ramp rate. A power supply system.

2. In claim 1, The lamp rate adjustment unit is a power supply system that notifies the first power supply to return the reset lamp rate to the original lamp rate when no fluctuation is observed in the output voltage value of the first power supply.

3. In a power supply system that supplies power to a load, a first power supply including a first power source and a power supply circuit; a second power supply connected in parallel with the first power supply and including a second power source, which is a different type of power source from the first power source, and a power supply circuit; and a power management device, wherein power is supplied to the load from the first power supply and the second power supply, the power supply circuits included in the first power supply and the second power supply each include an output voltage control unit that controls the output voltage output by the power supply based on a voltage command value, a droop characteristic calculation unit that calculates the voltage command value so that the output voltage droops at a predetermined droop rate with respect to the output power output by the power supply, and a lamp rate control unit that corrects the voltage command value to suppress the change amount of the output voltage when the change amount of the output power per unit time exceeds a predetermined lamp rate. The power management device sets a lamp rate for each of the first power supply and the second power supply, and makes the lamp rate set for the first power supply different from the lamp rate set for the second power supply. The first power supply is a power supply using a fuel cell as a power source, the first power supply includes a fuel supply system that supplies fuel to the fuel cell, the power management device includes a lamp rate adjustment unit that is notified of the output voltage value of the first power supply from the power supply circuit of the first power supply and the fuel flow rate value supplied by the fuel supply system to the fuel cell from the fuel supply system. The lamp rate adjustment unit is a power supply system that, when a fluctuation is observed in the output voltage value of the first power supply, notifies the first power supply of a reset lamp rate that decreases the lamp rate set for the first power supply by a predetermined width when the ratio of the change rate of the output voltage value of the first power supply to the change rate of the fuel flow rate value exceeds a predetermined ratio.

4. In claim 3, when no fluctuation is observed in the output voltage value of the first power supply, the lamp rate adjustment unit notifies the first power supply to return the reset lamp rate to the original lamp rate. A power supply system.

5. In a power supply system that supplies power to a load from a plurality of power supplies connected in parallel, a power management device that manages the plurality of power supplies, the plurality of power supplies in the power supply system each include a power source and a power supply circuit, and the power supply circuits included in the plurality of power supplies each include an output voltage control unit that controls the output voltage output by the power supply based on a voltage command value, a droop characteristic calculation unit that calculates the voltage command value so that the output voltage droops at a predetermined droop rate with respect to the output power output by the power supply, and a lamp rate control unit that corrects the voltage command value to suppress the change amount of the output voltage when the change amount of the output power per unit time exceeds a predetermined lamp rate, having a lamp rate setting unit that sets a lamp rate for each of the plurality of power supplies, the lamp rate setting unit makes the lamp rate set for a first power supply included in the plurality of power supplies different from the lamp rate set for a second power supply included in the plurality of power supplies and having a type of power source different from the power source of the first power supply, the first power supply is a power supply using a fuel cell as a power source, and includes a minimum cell voltage calculation unit that monitors the output voltage of the battery cell group constituting the fuel cell and notifies the power management device of the cell voltage value, which is the output voltage value of the battery cell that generates the minimum output voltage, having a lamp rate adjustment unit that receives notification of the output voltage value and the cell voltage value of the first power supply from the first power supply, when a fluctuation is observed in the output voltage value of the first power supply, if the cell voltage value exceeds a predetermined cell voltage threshold value, the lamp rate adjustment unit notifies the first power supply of the reset lamp rate that decreases the lamp rate set for the first power supply by a predetermined width. A power management device.

6. In a power supply system that supplies power from a plurality of power supplies connected in parallel to a load, a power supply management device that manages the plurality of power supplies, The plurality of power supplies in the power supply system each include a power source and a power supply circuit. The power supply circuits included in the plurality of power supplies each include an output voltage control unit that controls the output voltage output by the power supply based on a voltage command value, a droop characteristic calculation unit that calculates the voltage command value so that the output voltage droops at a predetermined droop rate with respect to the output power output by the power supply, and a ramp rate control unit that corrects the voltage command value to suppress the change amount of the output voltage when the change amount of the output power per unit time exceeds a predetermined ramp rate. It has a ramp rate setting unit that sets a ramp rate for each of the plurality. The ramp rate setting unit makes the ramp rate set for a first power supply included in the plurality of power supplies different from the ramp rate set for a second power supply included in the plurality of power supplies and having a different type of power source from the power source of the first power supply. The first power supply is a power supply using a fuel cell as a power source, and includes a fuel supply system that supplies fuel to the fuel cell. It has a ramp rate adjustment unit that is notified of the output voltage value of the first power supply from the power supply circuit of the first power supply and the fuel flow rate value supplied by the fuel supply system to the fuel cell from the fuel supply system. The ramp rate adjustment unit, when a change is observed in the output voltage value of the first power supply, and when the ratio of the change rate of the output voltage value of the first power supply to the change rate of the fuel flow rate value exceeds a predetermined ratio, notifies the first power supply of a reset ramp rate in which the ramp rate set for the first power supply is decreased by a predetermined width. A power supply management device.

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