JP7509010B2 - Power System - Google Patents

Description

The present invention relates to a power system.

Conventionally, this type of power system has been proposed to include a solar cell device, a power control device including an MPPT control device that receives the power generated by the solar cell device through MPPT (maximum power point tracking) control and an MPPT control device for external power reception that receives DC power from outside through MPPT control, a power generation device such as a generator or fuel cell device, and a power transmission device that transmits the power generated by the power generation device to the MPPT control device for external power reception (see, for example, Patent Document 1). The power transmission device includes a storage device that stores voltage-current characteristic data, and a voltage-current conversion unit that converts the voltage and current according to the DC power along a curve indicated by the voltage-current characteristic data, and converts the voltage-current characteristic of the DC power generated by the power generation device into a voltage-current characteristic having characteristics similar to the voltage-current characteristic of the DC power generated by the solar cell device and transmits it to the MPPT control device for external power reception. It is said that this makes it possible to receive the power generated by the power generation device through MPPT control.

JP 2015-192566 A

Fuel cell devices have the characteristic of deteriorating when their output is suddenly increased, and to prevent this, a power conditioner (DC/DC converter) generally places a limit on the rate of output change (e.g., rate limit). When MPPT control is performed on the output of the power conditioner, the rate of increase in the power extracted by MPPT control is faster than the rate limit, so there are cases where the output cannot keep up with the MPPT control.

The main objective of the power system of the present invention is to provide a power system that can suppress sudden changes in the output of a fuel cell device while allowing the output to closely follow MPPT control.

The power system of the present invention employs the following means to achieve the above-mentioned main objective.

The power system of the present invention comprises:
a fuel cell device that generates direct current power;
a converter device that converts DC power from the fuel cell device and outputs the converted DC power to a DC link section;
A capacitor connected to the DC link unit;
A power consumption device that consumes power;
a switch capable of connecting and disconnecting the DC link unit and the power consuming device;
a power supply control device connected to the DC link unit and configured to supply DC power from the DC link unit by MPPT control;
a control device that executes MPPT cooperative control to set a current-voltage characteristic of the DC link unit based on the power generated by the fuel cell device and the voltage of the DC link unit, set a target voltage of the DC link unit based on the current-voltage characteristic and an output current output from the DC link unit to the power supply control device, and control the switch so that the voltage of the DC link unit becomes the target voltage;
The gist of the invention is to provide the following:

In the power system of the present invention, the voltage of the DC link section is controlled by the power consumption of the power consuming device according to the current-voltage characteristics set based on the power generated by the fuel cell device, so that any maximum power can be output from the DC link section at any maximum voltage within the range of the power generated by the fuel cell device. As a result, a power system can be created that can suppress sudden changes in the output of the fuel cell device while allowing the output to follow the MPPT control well.

In such a power system of the present invention, the control device may set the current-voltage characteristics so that the maximum power is a predetermined amount or a predetermined percentage lower than the power generated by the fuel cell device. In this way, it is possible to appropriately deal with the deterioration of the fuel cell device over time, which is accompanied by a decrease in the power generated.

Furthermore, in the power system of the present invention, the control device may set a maximum power based on the power generated by the fuel cell device, and set an open end voltage and a maximum voltage based on the output voltage of the fuel cell device, and set the target voltage to _{Vlink_tag} calculated by the following formula (1) when the maximum power is _Ppeak , the open end voltage is _Vocv , the maximum voltage is _Vpeak , the voltage of the DC _{link unit} is Vlink, and the output current is _Ibattery . Calculating the target voltage using a formula eliminates the need to store a large number of maps for each maximum power and each maximum voltage, making it possible to reduce memory capacity.

In the power system of the present invention of this aspect, the control device may set the target voltage to V link_tag calculated by the following _formula (2) when _Pd is a _constant greater than 0 and less than the power generation power of the fuel cell device in a voltage range lower than the maximum voltage. When searching for maximum power (optimum operating point) by MPPT control, if an attempt is made to set a target voltage based on the current-voltage characteristic and the output current in a voltage range less than the maximum voltage, the current-voltage characteristic of the above formula (1) may cause a large change in voltage relative to a change in output current, resulting in a large pulsation of the target voltage. For this reason, by setting the target _voltage to V _{link_tag} calculated by formula (2) in a voltage range less than the maximum voltage, the pulsation of the target voltage can be suppressed.

Furthermore, the power system of the present invention may include an inverter device that converts the DC power of the DC link unit into AC power and connects it to a grid power source, a chargeable and dischargeable storage battery, and a storage battery converter device that is connected to the DC link unit and the storage battery and supplies power to the storage battery by MPPT control, and the power supply control device includes the storage battery converter device, and the control device may execute the MPPT cooperative control when the grid power source experiences a power outage and the fuel cell device operates independently.

1 is a schematic configuration diagram of a power system according to an embodiment of the present invention; 4 is a flowchart showing an example of a control routine when a power grid is stopped. 13 is a flowchart illustrating an example of an MPPT cooperative control process. 11 is an explanatory diagram showing an example of the PV characteristic and the IV characteristic of the DC link unit used when setting _a DC link voltage target value V _{link_tag} in a voltage range equal to or higher than the maximum voltage V _peak . 11 is an explanatory diagram showing an example of the PV characteristic and the IV characteristic of the DC link unit used when setting _a DC link voltage target value V _{link_tag} in a voltage range less than the maximum voltage V _peak . FIG.

Figure 1 is a schematic diagram of a power system 10 according to this embodiment. The power system 10 according to this embodiment is installed in a house or the like, and is configured as a system that is connected to a power grid 1 to supply power to a household load (external load), and includes a fuel cell device 20, a fuel cell power conditioner 30, a control device 40, a storage battery 50, and a storage battery power conditioner 51.

Although not shown, the fuel cell device 20 has a fuel cell module including a vaporizer that vaporizes reforming water to generate steam, a reformer that steam-reforms raw fuel gas (e.g., natural gas or LP gas) to generate fuel gas, a fuel cell stack (solid oxide fuel cell stack) that generates electricity by an electrochemical reaction between fuel gas and air, and an exhaust heat recovery device that converts exhaust heat from the fuel cell module into hot water using a heat exchanger and recovers it in a hot water storage tank. In addition, the fuel cell device 20 has auxiliary devices for operating the device, such as a gas pump that supplies raw fuel gas to the reformer, a water pump that pumps reforming water from a water tank and supplies it to the vaporizer, an air pump that supplies air to the fuel cell stack, a circulation pump that circulates hot water in a circulation pipe that connects the above-mentioned heat exchanger and the hot water storage tank, a heater 41 installed in the circulation path, and a radiator and a radiator fan installed downstream of the heater 41 in the circulation path. These auxiliary devices operate under the control of the control device 40. In addition, a current sensor 36a that detects the current output from the fuel cell stack (fuel cell current Ifc) is attached to the output terminal of the fuel cell stack, and a voltage sensor 36b that detects the terminal-to-terminal voltage of the fuel cell stack (fuel cell voltage _Vfc ) is attached between the output terminals of the fuel cell stack.

The fuel cell power conditioner 30 includes a DC/DC converter 31, an inverter 32, a relay 33, and a DC link unit 34.

The DC/DC converter 31 has switching elements and reactors (not shown), and by controlling the switching of the switching elements, converts (boosts) the DC power from the fuel cell device 20 into DC power of a predetermined voltage (e.g. DC 250V) and outputs it to the DC link section 34. Since the fuel cell device 20 has a characteristic that degradation easily progresses when the output is suddenly increased, in this embodiment, the DC/DC converter 31 converts power within the range of the output change rate by rate limit processing (slow change processing) so that the output of the fuel cell device 20 does not change beyond a predetermined output change rate.

The inverter 32 has switching elements and diodes (not shown), and by controlling the switching of the switching elements, converts the DC power of the DC link section 34 into AC power and supplies it to an external load.

The relays 33 are normally open switches, and are installed at the interconnection points (the output side of the inverter 32) of the wires connected to the corresponding phases of the system power supply 1.

A smoothing capacitor 35 is connected to the DC link unit 34, and a voltage sensor 37 for detecting the terminal-to-terminal voltage (DC link voltage V _link ) of the capacitor 35 is attached between the terminals of the capacitor 35. In addition, the above-mentioned heater 41 is connected to the DC link unit 34 via a heater switch 42 (FET), and other auxiliaries of the fuel cell device 20 and a control device 40 are connected to the DC link unit 34 via a DC/DC converter (not shown). These auxiliaries and the control device 40 are configured to operate by receiving DC power from the DC link unit 34.

The storage battery 50 is configured as, for example, a lithium ion secondary battery, and is connected to the DC link unit 34 via a storage battery power conditioner 51. The storage battery power conditioner 51 includes a DC/DC converter, and by controlling the switching of the DC/DC converter, charges the storage battery 50 with DC power from the DC link unit 34, and discharges the DC power from the storage battery 50 to the DC link unit 34. A current sensor 38 that detects the current flowing through the storage battery 50 (storage battery current I _battery ) is attached to the power line connecting the DC link unit 34 and the storage battery 50.

The battery power conditioner 51 is controlled by MPPT (maximum power point tracking) control using a control device (not shown) separate from the control device 40. MPPT control is a control for extracting current at the output voltage at which the power is maximized, and can use, for example, a hill climbing method in which the output voltage is changed by a predetermined amount so that the power tracks the maximum power (optimum operating point).

Although not shown, the control device 40 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a ROM for storing various programs, a RAM for temporarily storing data, and an input port and an output port. The fuel cell current Ifc from the current sensor 36a, the fuel cell voltage _Vfc from the voltage sensor 36b, the DC link voltage _Vlink from the voltage sensor 37, the storage battery current _Ibattery from the current sensor 38, and the like are input to the control device 40 via the input port. On the other hand, the control device 40 outputs control signals to the switching elements of the DC/DC converter 31, control signals to the switching elements of the inverter 32, a drive signal to the relay 33, a drive signal to the heater switch 42, and the like via the output port.

Next, the operation of the power system 10 thus configured will be described. In particular, the operation when the grid power supply 1 stops (power outage) will be described. FIG. 2 is a flowchart showing an example of a control routine executed by the CPU of the control device 40 when the grid power supply stops. This routine is executed when a voltage sensor (not shown) detects a drop in the grid voltage, i.e., a stop (power outage) of the grid power supply 1.

When the control routine for when the system power supply is stopped is executed, the CPU of the control device 40 first starts the independent power generation of the fuel cell device 20 (step S100). Independent power generation is an operating state in which all of the required output required by the external load is covered by the power output from the power system 10, and in this embodiment, the operation of the fuel cell device 20 is controlled so that the fuel cell device 20 generates power at the rated maximum output (e.g., 700 W). In the independent power generation state, when the required output is equal to or less than the generated power of the fuel cell device 20, the fuel cell power conditioner 30 and the storage battery power conditioner 50 are controlled so that the power corresponding to the required output is supplied to the external load by the generated power of the fuel cell device 20 and the surplus power is consumed by the heater 41 or charged to the storage battery 50. In addition, when the required output exceeds the generated power of the fuel cell device 20, the fuel cell power conditioner 30 and the storage battery power conditioner 50 are controlled so that the power corresponding to the required output is supplied to the external load by the discharge power from the storage battery 50 in addition to the generated power from the fuel cell device 20.

When the independent power generation is started, the heater switch 42 is driven and controlled so that the DC link voltage _Vlink becomes a predetermined voltage Vset (for example, 230V, 240V, or 250V) by the power consumption of the heater 41 (step S110). Then, the generated power _Pfc of the fuel cell device 20 is input (step S120), and it is determined whether the input generated power _Pfc is equal to or greater than the threshold Pref (step S130). Here, the generated power _Pfc can be calculated based on the fuel cell current Ifc detected by the current sensor 36a and the fuel cell voltage _Vfc detected by the voltage sensor 36b and input. The threshold Pref is a threshold for determining whether the output of the fuel cell device 20 is stable, and in this embodiment, it is set to a value close to the rated maximum output. If it is determined that the generated power _Pfc is not equal to or greater than the threshold Pref, the process returns to step S110.

On the other hand, when it is determined that the generated power _Pfc is equal to or greater than the threshold Pref, the MPPT cooperative control is started (step S140). The MPPT cooperative control is a control for making the output of the DC link unit 34 follow the MPPT control performed by the storage battery power conditioner 51, and is executed by the MPPT cooperative control process of Fig. 3. The MPPT cooperative control process will be described below.

In the MPPT cooperative control, first, the generated power P _fc , the fuel cell voltage V _fc from the voltage sensor 36b, the DC link voltage V _link from the voltage sensor 37, and the storage battery current I _battery from the current sensor 38 are input (step S200). Next, a value (P _fc -ΔP) obtained by subtracting a predetermined power ΔP from the input generated power P _fc is set as the maximum power P _peak , a value (k·V _fc ) obtained by multiplying the input fuel cell voltage V _fc by a coefficient k is set as the open circuit voltage V _ocv , and a value (V _ocv -ΔV) obtained by subtracting a predetermined voltage ΔV from the set open circuit voltage V _ocv is set as the maximum voltage V _peak (step S210). Here, the maximum power P _peak , the open circuit voltage V _ocv , and the maximum voltage V _peak are parameters that define the power-voltage characteristics (P-V characteristics) of the DC link unit 34. The maximum power _Ppeak is set within the range of the power generation power _Pfc of the fuel cell device 20, and the predetermined power ΔP is an adjustment amount of the maximum power _Ppeak in the MPPT cooperative control, and is set to, for example, 50 W or 60 W. The maximum power _Ppeak may be set by multiplying the power generation power _Pfc by a coefficient greater than 0 and less than 1. The coefficient k is the transformation ratio of the DC/DC converter 31. The predetermined voltage ΔV is set to, for example, 20 V or 30 V, within a range in which the auxiliary devices and the control device 40 connected to the DC link unit 34 do not lose power even if a voltage drop occurs in the DC link unit 34 due to the MPPT control.

Next, it is determined whether the input battery current I _battery is less than a predetermined current Iref (step S220). This process is for determining whether the DC link voltage target value V _{link_tag} is set in _a voltage range equal to or greater than the maximum voltage V _peak . If it is determined that the battery current I _battery is less than the predetermined current Iref, a DC link voltage target value V _{link_tag} is _calculated by the following equation (1) based on the maximum power P _peak , the maximum voltage V _peak , the open circuit voltage V _ocv , the DC link voltage V _link , and the battery current I _battery (step S230). Then, an on-off duty ratio of the heater switch 42 is set by feedback control (e.g., proportional-integral control) based on the deviation between the calculated DC link voltage target value V _{link_tag and} the DC link voltage V _link input in step S200, and switching control of the heater switch 42 is performed based on the set on-off duty ratio (step S250), and the MPPT coordinated control process is terminated. FIG _. 4 is an explanatory diagram showing an example of the P-V characteristic and the I-V characteristic of the DC link unit used when setting the DC link voltage target value V _{link_tag} in a voltage range equal to or _higher than the maximum voltage V peak. Equation (1) is an equation (first calculation formula) corresponding to the power-voltage characteristic (P-V characteristic) and the current-voltage characteristic (I-V characteristic) of the DC link unit 34 shown by the solid line in FIG. 4, and by calculating the DC link voltage target value V _{link_tag} using _the first calculation formula, it is possible to extract power from the DC link unit 34 along the P-V characteristic and the I-V characteristic. By determining the P-V characteristic and the I-V characteristic based on the generated power P _fc of the fuel cell device 20 and controlling the DC link voltage V _link along these characteristics, it _is possible to extract any maximum power P _peak at any maximum voltage V _peak from the DC link unit 34 within the range of the generated power P fc. This makes it possible to actively control the power supplied to the storage battery power conditioner 51 that performs MPPT control. Moreover, since the surplus power of the generated power _Pfc of the fuel cell device 20 relative to the maximum power _Ppeak is consumed by the heater 41, there is no sudden increase in the output of the fuel cell device 20, and it is possible to suppress the progression of deterioration of the fuel cell device 20 due to a sudden increase in output. Furthermore, since an arbitrary maximum voltage _Vpeak can be set, by setting a relatively high voltage as the maximum voltage _Vpeak , it is possible to suppress a large decrease in the DC link voltage Vlin in the process of searching for the maximum power (optimum operating point) by MPPT control, and it is possible to avoid the risk of power loss for the accessories connected to the DC link unit 34 and the control device 40.

On the other hand, when it is determined that the storage battery current I _battery is not less than the predetermined current Iref but is equal to or greater than the predetermined current Iref, a DC link voltage target value V _{link_tag} is calculated by the following equation (2) based on the maximum power P _peak , the maximum voltage V _peak , the open circuit voltage V _ocv , the DC link voltage V _{link ,} the storage battery current I _battery and the constant P _d (step S240). Then, the heater switch 42 is switched and controlled by feedback control based on the deviation between the calculated _DC link voltage target value V _{link_tag} and the DC link voltage V _link input in step S200 (step S250), and the MPPT coordinated control process is terminated. FIG. 5 is an explanatory diagram showing an example of the P-V characteristic and the I-V _{characteristic} of the DC link section used when setting the DC link voltage target value V _{link_tag} in a voltage range less than the maximum voltage V _peak . In the figure, the solid line indicates the characteristic used when _the DC link voltage target value V _{link_tag} is set in a voltage range below the maximum voltage V _peak , and the dashed line indicates the characteristic used when the DC link voltage target value V _{link_tag} is set in _a voltage range equal to or greater than the maximum voltage V _peak . Equation (2) is an equation (second calculation formula) corresponding to the power-voltage characteristic (P-V characteristic) and current-voltage characteristic (I-V characteristic) shown by the solid line in FIG. 5, and by calculating the DC link voltage target value V _{link_tag} using the second calculation _formula , it is possible to extract power from the DC link unit 34 in accordance with the P-V characteristic and the I-V characteristic. In equation (2), "P _d " indicates the value of the output power when V _{link_tag} is a value of 0 in the P-V characteristic, and is set to a value (e.g., 100 or 200) that is _greater than the value 0 and smaller than the rated maximum output. This allows the I-V characteristic to have a slope in the voltage range less than the maximum voltage V _peak . In the above-described first calculation formula, the slope of the I-V characteristic is flat in a voltage range below the maximum voltage V _peak , so that the DC link voltage target value V _{link_tag} pulsates significantly in response to a slight change in the storage battery current I _battery . In contrast, in the second calculation formula, the I-V characteristic can be made to have a slope in comparison with the first calculation formula, so that the DC link voltage target value V _{link_tag} can be prevented from pulsating significantly in response to a change in _the storage battery current I _battery , and the DC link voltage V _link can be maintained within an appropriate range. For _example , it is possible to avoid the risk of power loss to the auxiliary devices and the control device 40 due to a large drop in the DC link voltage V _link .

Returning to the control routine when the grid power supply is stopped, the MPPT cooperative control is started and continued until the grid power supply 1 is restored based on the grid voltage (step S150). When it is determined that the grid power supply 1 has been restored, the MPPT cooperative control is stopped (step S160), and the independent power generation is stopped (step S170), and this routine is terminated.

In the power system 10 of the present embodiment described above, the current-voltage characteristic (calculation formula) is set based on the power generation power _Pfc of the fuel cell device 20, the DC link voltage target value _{Vlink_tag} is set based on the current-voltage characteristic, the DC link _{voltage Vlink} , and the storage _battery current Ibattery, and MPPT coordinated control is performed to control the heater switch 42 so that the DC link voltage _Vlink coincides _with the DC link voltage target value _{Vlink_tag} . By controlling the DC link voltage _Vlink by the power consumption of the heater 41 as a power consumption device in accordance with the current-voltage characteristic set based on the power generation power _Pfc of the fuel cell device 20, it is possible to output any maximum power _Ppeak from the DC link unit 34 at any maximum voltage _Vpeak within the range of the power generation power _Pfc . As a result, it is possible to provide a power system 10 that can suppress a sudden change in the output of the fuel cell device 20 while allowing the output to follow the MPPT control well.

Furthermore, in the power system 10 of this embodiment, MPPT cooperative control is performed using current-voltage characteristics in which the maximum power _Ppeak is set to a power that is lower than the power generation power _Pfc by the fuel cell device 20 by a predetermined power ΔP. This makes it possible to appropriately deal with deterioration over time of the fuel cell device 20 by simple processing.

Furthermore, in the power system 10 of the present embodiment, a maximum power _Ppeak is set based on the power generation power _Pfc of the fuel cell device 20, and a DC link voltage target value _{Vlink_tag} is calculated by formulas (first formula, second formula) based on the maximum power _Ppeak , the DC link voltage _Vlink , and the storage _battery current _Ibattery . This eliminates the need to store a large number of maps and reduces the memory storage capacity, compared to storing a large number of I-V characteristic maps for each maximum power _Ppeak and each maximum voltage _{Vpeak and} setting the DC link voltage target value _{Vlink_tag} using an I-V characteristic _map selected based on the power generation power Pfc.

Furthermore, in the power system 10 of the present embodiment, when the storage battery current I _battery is equal to or higher than a predetermined current Iref, in a voltage range less than the maximum voltage V _peak , the DC link voltage target value V _{link_tag} is calculated using a second calculation formula in which _{the I-V characteristics are inclined as compared to the first calculation formula. This makes it possible to suppress large pulsations in the DC link voltage target value V link_tag in} the process of searching for _an optimal operating point by MPPT control.

In the above-described embodiment, when the battery current I _battery is less than the predetermined current Iref _, the DC link voltage target value V _{link_tag} is calculated using the first calculation formula, and when the battery current I _battery is equal to or greater than the predetermined current Iref, the DC link voltage target value V _{link_tag} is calculated using the second calculation formula. However, the DC link voltage target value V _{link_tag} may be calculated using _the first calculation formula regardless of the battery current I _{battery .}

In the above-described embodiment, the DC link voltage target value V _{link_tag} is set using a calculation formula, but the DC link voltage target value V _{link_tag} may be set using a map of the characteristics shown in Fig. 4 or 5. In this case, the DC link voltage target value V _{link_tag} may be set using _a different map depending on the power _generation power P _fc and the fuel cell voltage V _fc of _the fuel cell device 20.

The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, the fuel cell device 20 corresponds to the "fuel cell device", the DC link unit 34 corresponds to the "DC link unit", the DC/DC converter 31 corresponds to the "converter device", the capacitor 35 corresponds to the "capacitor", the heater 41 corresponds to the "power consumption device", the heater switch 42 corresponds to the "switch", the storage battery power conditioner 51 corresponds to the "power supply control device", and the control device 40 corresponds to the "control device". Also, the inverter 32 corresponds to the "inverter device", the storage battery 50 corresponds to the "storage battery", and the storage battery power conditioner 51 corresponds to the "storage battery converter device".

The correspondence between the main elements of the embodiment and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the embodiment is an example for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving the Problem column should be based on the description in that column, and the embodiment is merely a specific example of the invention described in the Means for Solving the Problem column.

The above describes the form for carrying out the present invention using an embodiment, but the present invention is not limited to such an embodiment in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the spirit of the present invention.

The present invention can be used in the power system manufacturing industry, etc.

1 System power supply, 10 Power system, 20 Fuel cell device, 30 Fuel cell power conditioner, 31 DC/DC converter, 32 Inverter, 33 Relay, 34 DC link section, 35 Capacitor, 36a Current sensor, 36b Voltage sensor, 37 Current sensor, 38 Current sensor, 40 Control device, 41 Heater, 42 Heater switch, 50 Storage battery power conditioner, 50 Storage battery, 51 Storage battery power conditioner.

Claims (5)

a fuel cell device that generates direct current power;
a converter device that converts DC power from the fuel cell device and outputs the converted DC power to a DC link section;
A capacitor connected to the DC link unit;
A power consumption device that consumes power;
a switch capable of connecting and disconnecting the DC link unit and the power consuming device;
a power supply control device connected to the DC link unit and configured to supply DC power from the DC link unit by MPPT control;
a control device that executes MPPT cooperative control to set a current-voltage characteristic of the DC link unit based on the power generated by the fuel cell device and the voltage of the DC link unit, set a target voltage of the DC link unit based on the current-voltage characteristic and an output current output from the DC link unit to the power supply control device, and control the switch so that the voltage of the DC link unit becomes the target voltage;
A power system comprising: 2. The power system of claim 1,
the control device sets the current-voltage characteristic so that a power that is a predetermined amount or a predetermined percentage lower than a power generated by the fuel cell device becomes a maximum power.
Power system. 3. The power system according to claim 1,
The control device sets a maximum power based on the power generated by the fuel cell device, and also sets an open end voltage and a maximum voltage based on the output voltage of the fuel cell device, and when the maximum power is _Ppeak , the open end voltage is _Vocv , the maximum voltage is _Vpeak , the voltage of the DC link unit is _Vlink , and the output current is _Ibattery , the control device sets _{Vlink_tag} calculated by the following _formula (1) to the target voltage.
Power system.

4. The power system of claim 3,
The control device sets V _{link_tag} calculated by the following formula (2) as the target voltage when a constant _Pd is greater than 0 and less than the power generation power of the fuel cell device in a _voltage range lower than the maximum voltage.
Power system.

5. The power system according to claim 1,
an inverter device that converts the DC power of the DC link unit into AC power and connects the AC power to a power system;
A rechargeable storage battery;
a converter device for a storage battery connected to the DC link unit and the storage battery and configured to supply power to the storage battery by MPPT control;
Equipped with
the power supply control device includes the storage battery converter device,
The control device executes the MPPT cooperative control when the grid power supply is interrupted and the fuel cell device is operated independently.
Power system.

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