JP5707861B2 - Power generation system - Google Patents

Description

  The present invention relates to a fuel power generation device (for example, a fuel cell power generation device) that generates power by consuming fuel, and a natural power generation device (for example, a solar power generation device or a wind power generation device) that uses natural energy (for example, sunlight or wind power). In particular, a power generation system in which a plurality of types of distributed power sources including a power system are connected to an electric power system, particularly when executing a voltage rise suppression control during the simultaneous power generation of the plurality of types of distributed power sources, Accordingly, the present invention relates to a technique in which a decrease in power generation efficiency can be avoided by performing voltage rise suppression in cooperation with each other.

  Conventionally, a power conditioner is used to convert DC power generated by solar power generation into AC power and to perform grid connection control for supplying power to a commercial power system. And when connecting the distributed power supply by a solar power generation device with an electric power grid | system, it is known to perform voltage rise suppression control with a power conditioner (for example, refer patent document 1). In addition, it has been reported that by performing such voltage rise suppression control, generated power is wasted in the photovoltaic power generation module, and as a result, power generation efficiency is reduced (see, for example, Patent Document 2).

JP 2008-35640 A Japanese Patent No. 3942400

  By the way, in the case of fuel cell power generation, fuel is required for power generation, whereas in the case of solar power generation, wind power generation, etc., natural energy is used, so there is no such situation. In other words, fuel cell power generation involves finite fuel consumption.

  On the other hand, fuel cell power generation requires time and effort to start and stop the fuel cell power generation, and changes in the amount of power generation can be controlled only moderately. On the other hand, in the case of photovoltaic power generation, there is a circumstance that the power generation amount itself can be changed easily and quickly by changing the AC conversion output in the power conditioner. Further, in the case of fuel cell power generation, not only electric power but also heat recovery is usually performed, and the recovered heat is used for hot water supply or the like. If the power generation amount decreases, the heat recovery also decreases accordingly. .

  Therefore, if the voltage rise suppression control is individually performed for each distributed power source by the power conditioners provided in each of the plurality of distributed power sources, it may take time to increase the voltage again, or the recovered heat It will cause a situation that may interfere with the use of.

  The present invention has been made in view of such circumstances, and the object of the present invention is to generate power in the sense of suppressing fuel consumption by using natural energy as much as possible when executing the voltage rise suppression control. An object is to provide a power generation system capable of improving efficiency. Also, it is possible to provide a power generation system capable of executing voltage rise suppression control while preventing the heat recovery demand from being hindered according to the heat recovery demand on the fuel power generation side that generates power by consuming fuel. Also aimed.

In order to achieve the above object, the present invention is directed to a power generation system in which a natural power generation device that generates power using natural energy and a fuel power generation device that generates power by consuming fuel are connected to an electric power system. The following specific matters were prepared. That is, a power conditioner provided in the natural power generation device, a power conditioner provided in the fuel power generation device, and a control unit for performing voltage increase suppression control are provided. When the natural power generation device and the fuel power generation device perform the voltage increase suppression control during the simultaneous power generation operation as the control unit, the respective characteristics or the current situation of the natural power generation device and the fuel power generation device In accordance with the configuration, the power conditioner of both the natural power generation apparatus and the fuel power generation apparatus is configured to link and control both the power conditioners so as to give priority to the suppression process of the output voltage by the power conditioner , and When the current situation regarding the heat utilization on the fuel power generation device side is a large heat demand when executing the voltage rise suppression control, the output voltage of the power grid for the power conditioner on the natural power generation device side is targeted. The linkage control that prioritizes the suppression process is executed (claim 1).

The further, as the control unit, combining viewed linkage control intended for the power conditioner of the fuel generator unit side to prioritize suppression processing of the output voltage to the electric power system in performing the voltage increase suppression control (Claim 2 ).

  In the case of the present invention, when performing the voltage rise suppression control, the linkage control that gives priority to the output voltage suppression processing for the power system is performed for the power conditioner on the fuel power generation device side, thereby suppressing the voltage rise suppression. In addition, fuel consumption in the fuel power generation device can be reduced. In addition, when the current state of heat utilization on the fuel power generation device side is a large heat demand when executing the voltage rise suppression control, the output voltage to the power system is targeted at the power conditioner on the natural power generation device side. By controlling linkages that give priority to the suppression process, the heat demand can be reduced depending on the current demand level of heat demand such as hot water supply, heating, or heat storage by heat recovery. It is possible to satisfy the request with priority.

When giving priority to the output voltage suppression processing as the control unit of the present invention, the priority output voltage suppression processing precedes the other side, and / or the priority output voltage. It is possible to adopt a configuration in which a process for increasing the amount of suppression of the above is performed on the other side (claim 3 ). By doing so, it is possible to reliably realize suppression of voltage rise while obtaining the effect of priority.

Further, as the control unit of the present invention, provided in each of the power conditioner of the natural power generation device and the power conditioner of the fuel power generation device, both control units are communicably connected so that the voltage rise is suppressed. It can be set as the structure which performs control (Claim 4 ), Or, as a control part of this invention, it mutually communicates with each of the power conditioner of the said natural power generation apparatus, and the power conditioner of the said fuel power generation apparatus It can also be set as the structure connected by communication so that the said voltage rise suppression control is performed (Claim 5 ). Various forms of communication connection can realize the linkage control of the present invention.

In addition, a solar power generation device can be used as the natural power generation device in the present invention (Claim 6 ), and a fuel cell power generation device or a gas engine power generation device can be used as the fuel power generation device in the present invention (Claim 7 ). ).

As described above, according to the power generation system of the present invention, the natural power generation device and the fuel power generation device can be controlled during the voltage rise suppression control according to the respective characteristics or the current situation of the natural power generation device and the fuel power generation device. It is possible to prioritize the suppression process of the output voltage by the power conditioner on either side, and by generating appropriate voltage rise suppression by linkage control according to the characteristics of different types of power generators or the current situation Ru can also be achieved to improve the efficiency. In addition, when the current situation of heat utilization on the fuel power generation device side is a large heat demand when executing the voltage rise suppression control, the output to the power system is targeted at the power conditioner on the natural power generation device side. Since the linkage control that prioritizes voltage suppression processing is performed, depending on the circumstances such as the degree of demand for current heat demand such as hot water supply, heating or heat storage by heat recovery, while suppressing voltage rise It will be possible to prioritize and satisfy this demand for heat.

  In particular, according to the second aspect of the present invention, when performing the voltage rise suppression control, the linkage control is performed so as to give priority to the output voltage suppression processing for the power system for the power conditioner on the fuel power generation device side. The fuel consumption in the fuel power generation device can be reduced while suppressing the voltage rise.

According to the third aspect of the present invention , in the case where priority is given to the output voltage suppression process, the priority output voltage suppression process is preceded by the other side and / or the priority output voltage suppression. By adopting a configuration that executes the process of making the amount larger than that on the other side, it is possible to reliably realize suppression of voltage rise while obtaining the effect of priority.

According to claim 4 or claim 5 , the linkage control of the present invention can be reliably realized by various forms of communication connection.

According to Claim 6 or Claim 7 , it can specify concretely as a natural power generation device or a fuel power generation device in this invention.

It is a schematic diagram which shows the whole conceptual diagram of the electric power generation system of this invention. It is a schematic diagram which shows the example of the fuel cell electric power generating apparatus of FIG. It is a schematic diagram which shows the example of the power conditioner of FIG. It is a flowchart for setting which power conditioner of FIG. 1 leads voltage rise suppression control. It is a flowchart first half part of the voltage rise suppression control with which the control part of each power conditioner is provided. It is a flowchart latter half part of the voltage rise suppression control with which the control part of each power conditioner is provided. FIG. 7A shows the relationship between the voltage rise suppression control unit and a plurality of power conditioners. FIG. 7A shows the case where the control unit (voltage rise suppression control unit) is provided in each power conditioner. FIG. 7B shows a case where a control unit (voltage rise suppression control unit) is provided in any one power conditioner, and the other power conditioners are controlled by this one control unit. FIG. 7C shows a case where a plurality of power conditioners are controlled by one independent control unit (voltage rise suppression control unit).

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

  FIG. 1 shows a power generation system according to an embodiment of the present invention. This power generation system includes a natural power generation device (for example, a solar power generation device) NP that uses natural energy (for example, sunlight) as a plurality of distributed power sources and a fuel cell power generation device FP as a fuel power generation device that consumes fuel to generate power. The plurality of distributed power sources are interconnected with the commercial power system 1. Both distributed power sources of the natural power generator NP and the fuel cell power generator FP are each provided with a power conditioner 2, and this power conditioner 2 performs DC-AC conversion (AC conversion) on each distributed power source side as will be described later. In addition, power control is performed so that power distribution to the household load 3 and power transmission to the power system 1 are possible.

  FIG. 2 shows an example of a power generation device using a solid oxide fuel cell as the fuel cell power generation device FP, and cogeneration is possible. Reference numeral 4 in the figure denotes a battery body, and the battery body 4 includes a cell stack 41, a reformer 42, and an air heat exchanger 43. The supply of fuel gas, air, water vapor, etc. to the battery body 4 and the discharge of exhaust gas are all performed through the preheater / evaporator 5. A fuel gas circuit 6, a reforming air supply circuit 7 and a cathode air supply circuit 8 are passed through the preheating / evaporator 5, while exhaust gas is introduced from the battery body 4 side as a heat source for preheating and water is supplied. The pure water led to the processing circuit 9 and obtained by collecting the moisture in the exhaust gas is returned to the fuel gas circuit 6 in the preheater / evaporator 5 and converted into steam for steam reforming.

  The cell stack 41 is configured such that a plurality of cells are erected with a predetermined interval, and each cell has a small-diameter cylindrical anode (fuel electrode) and a large-diameter cylindrical shape covering the outer peripheral side. The cathode (air electrode) is integrated concentrically with an electrolyte sandwiched between them. The anode and the cathode are both made of ceramics containing a metal oxide such as Ni, and the electrolyte is made of a solid oxide such as YSZ (yttrium stabilized zirconia).

  The fuel gas supplied from the reformer 42 is caused to flow from the lower end to the upper end to the inner hole of the anode of the cell, and the cathode air is supplied from the air heat exchanger 43 to the outer peripheral surface of the cathode. It has become. At the cathode, oxygen in the cathode air becomes oxygen ions and passes through the electrolyte. At the anode, it reacts with hydrogen in the fuel gas to produce water (water vapor), and the electrons generated at that time move to the cathode side through the circuit. Electricity is generated by repeatedly ionizing oxygen again. After the fuel gas supplied to the inner hole of the anode is used for the above reaction, it is led to the reformer burner as an off gas and used as a fuel for combustion. The cathode air is exhausted upward and sent to the preheater / evaporator 5 as exhaust gas together with the combustion exhaust gas from the reformer burner. At that time, the exhaust gas passes through the air heat exchanger 43 as a heat source for heating the air.

  The fuel gas circuit 6 is provided with a regulating valve 61 composed of an original gas solenoid valve, a governor, and the like, a buffer tank 62, a gas flow sensor 63, a desulfurizer 64, a check valve 65, and the like, and the preheat / evaporator 5 The reforming air supply circuit 7 joins before entering. The reforming air supply circuit 7 includes a reforming air blower 71 that sucks and sends the air through a filter (not shown), a buffer tank 72, a reforming air flow sensor 73, a check valve 74, and the like. And are intervened. The fuel gas circuit 6 joined with the reforming air supply circuit 7 is supplied with pure water from the water supply processing circuit 9 in the preheating / evaporator 5, and the pure water is supplied to the preheating / evaporator 5. In FIG. 2, the vaporized gas is sent to the reformer 42 in a state of being evaporated into water vapor. Similarly to the reforming air supply circuit 7, the cathode air supply circuit 8 sucks and sends the air through a filter (not shown), a buffer tank 82, a cathode air flow sensor 83, and the like. And are intervened.

  The water supply processing circuit 9 recovers the water contained in the exhaust gas after passing through the preheater / evaporator 5, purifies the collected condensed water, stores the purified water after the purification, and uses the stored pure water as water vapor. This is a circuit for performing the preheating and supplying to the evaporator 5 for reuse. The water supply processing circuit 9 includes a heat exchanger 91 for exhaust heat recovery, a drain tank 92 that temporarily stores the condensed water collected by the heat exchanger 91, a water supply pump 93, and purified water. A water refining unit 94 made of a reverse osmosis membrane (RO membrane), an ion exchange membrane, and the like, a pure water flow rate sensor 95 for detecting a pure water flow rate, and a check valve 96 are sequentially provided from the upstream side. The pure water supplied from the water supply processing circuit 9 to the preheater / evaporator 5 is evaporated by the preheater / evaporator 5 to form water vapor and supplied to the reformer 42 and the anode side of the battery body 4. . In the heat exchanger 91 for exhaust heat recovery, the exhaust heat recovery heat exchanger 91 is recovered from the circulation circuit 101 on the hot water storage unit 10 side by recovering the latent heat of the exhaust gas after sensible heat recovery by the preheater / evaporator 5. The water circulated and supplied to the heat exchanger is heated by heat exchange.

  Hot water heated and heated by heat exchange in the exhaust heat recovery heat exchanger 91 is returned to the hot water storage tank 102 and stored. Thereby, heat recovery from the exhaust gas of the fuel cell is achieved, and the recovered heat is stored in the hot water storage tank 102 in the state of hot water. A circulation pump 103 and a cooling radiator 104 are interposed in the circulation circuit 101 of the hot water storage unit 10. When the circulation pump 103 is operated, hot water is taken out from the bottom of the hot water storage tank 102 and is then sent to the heat exchanger 91 for exhaust heat recovery. By the heat exchange with the exhaust gas in the heat exchanger 91 for exhaust heat recovery, The hot water heated to a high temperature is circulated so as to be returned to the top of the hot water storage tank 102. Then, in the auxiliary heat source unit 104, the hot water led out from the hot water storage tank 102 is heated by the combustion heat of the built-in combustion burner, and after being auxiliary heated to a predetermined temperature, the hot water is discharged for hot water supply to a hot water tap (not shown). Or, the hot water is discharged from a bathtub (not shown) for hot water filling or the like.

  As described above, in the fuel cell power generation device FP, since various components are involved in a complicated manner, it takes a considerable time to start or stop the power generation operation, or to change the power generation amount. On the hot water storage unit 10 side, heat is used for hot water supply, hot water filling, hot water supply as a heat source for hot water heating, etc. by exhaust heat recovery, or for such heat use, in the hot water storage tank 102 If the amount of stored heat (the amount of hot water stored above the specified temperature) is insufficient and heat storage is being performed by heat exchange heating, etc., the situation on the power generation side when changing the amount of power generated to meet these heat demands In addition, it is necessary to consider the situation from the aspect of heat utilization.

  FIG. 3 shows an example of the power conditioner 2. The power conditioner 2 boosts the DC power generated by the natural power generator NP or the fuel cell power generator FP to a predetermined voltage, and the boosted DC. The inverter including the inverter unit 22 that converts electric power into AC power and outputs the power, the interconnection relay unit 23 that switches the connection / disconnection between the power system 1 by opening and closing, and the voltage rise suppression control unit. And a control unit 24 that performs output control of the unit 22 and the like. The control unit 24 provided in the power conditioner 2 on the natural power generation device NP side and the control unit 24 provided in the power conditioner 2 on the fuel cell power generation device FP side can communicate with each other via a communication line 25. Connected to each other.

  When the voltage rise suppression control by the voltage rise suppression control unit detects a situation where the system voltage exceeds a predetermined threshold (for example, less than 107V), each distributed power source (natural power generator NP or fuel cell power generator FP) The output voltage on the power conditioner 2 is controlled so as to be lower than the voltage value on the system power side at that time, in particular the inverter unit 22 of the power conditioner 2. The control unit 24 of the power conditioner 2 on the natural power generation device NP side and the control unit 24 of the power conditioner 2 on the fuel cell power generation device FP side are provided with the same voltage increase suppression control unit. When it is detected that the system voltage exceeds a threshold value, the two control units 24 and 24 perform voltage rise suppression control in cooperation with each other. Specifically, one of the two voltage control units 24, 24 leads the execution of the voltage rise suppression control, and the other voltage rise suppression control unit controls the voltage rise suppression control on the leading side. The control signal from the unit is received via the communication line 25 and is subordinated. Regardless of which initiative is taken, information indicating that a voltage equal to or higher than the threshold value has been detected is shared by communicating between the initiative side and the subordinate side.

  Which of the control units 24 and 24 takes the lead is determined based on preset setting information (for example, setting by a Dip switch), or if there is no such prior setting information. The power conditioner 2 detects the occurrence of a situation where the system voltage exceeds a threshold value.

  FIG. 4 shows an example of such initiative setting processing. First, it is determined whether or not the control unit 24 on the fuel cell power generation device FP side is led by the prior setting information (step S1). If the control unit 24 on the fuel cell power generation device FP side is set to take the lead (YES in step S1), the subsequent voltage rise suppression control is executed by the control unit 24 on the fuel cell power generation device FP side. (Step S2), conversely, if the control unit 24 on the natural power generator NP side is set to take the lead (NO in step S1, YES in step S3), the subsequent voltage rise suppression The control is led by the control unit 24 on the natural power generator NP side (step S4). On the other hand, if there is no such prior setting information (NO in step S3), it is determined whether or not a voltage equal to or higher than a threshold value to be suppressed is detected in both the fuel cell power generation device FP and the natural power generation device NP (step S3). S5). If it is detected on both sides (YES in step S5), and it is preset that the fuel cell power generation device FP takes the lead in the case of simultaneous detection (YES in step S6), the subsequent voltage rise The execution of the suppression control is led by the control unit 24 on the fuel cell power generation device FP side (step S2). On the other hand, in the case of simultaneous detection, if it is preset that the natural power generator NP side takes the lead (NO in step S6), the subsequent execution of the voltage increase suppression control is controlled by the natural power generator NP side. The unit 24 takes the lead (step S4). On the other hand, if a voltage higher than the threshold value is detected on only one side in step S5 (NO in step S5), if it is detected on the fuel cell power generation device FP side (YES in step S7), The execution of the voltage rise suppression control is led by the control unit 24 on the fuel cell power generation device FP side (step S2). Conversely, if it is detected on the natural power generator NP side (NO in step S7), the control unit 24 on the natural power generator NP side takes the lead in executing the subsequent voltage increase suppression control (step S4). By adopting a setting method in which the control unit 24 on the side of the power generation device (natural power generation device NP or fuel cell power generation device FP) that has previously detected a voltage equal to or higher than the threshold is used, the following effects are obtained. be able to. That is, even if there is a variation in detection accuracy between the voltage sensors of both the control units 24 and 24, the voltage rise is detected on the safe side, and the voltage rise suppression control is performed based on the information detected on the safe side. Will be able to.

  5 and 6 show examples of the voltage rise suppression control, and the contents of the voltage rise suppression control will be described with reference to these.

  Both the fuel cell power generation device FP and the natural power generation device NP perform normal power generation operation (step S11), and monitor whether or not the system voltage is less than a threshold value (suppression threshold; for example, 107V) to be suppressed (step S12). ). If the system voltage is maintained below the suppression threshold (YES in step S12), the control returns without performing the voltage increase suppression control and continues the normal power generation operation and the above monitoring (step S13).

  If it is detected in step S12 that the system voltage is equal to or higher than the suppression threshold (NO in step S12), first, the heat demand on the fuel cell power generation device FP side (request for heat recovery on the hot water storage unit 10 side) is generated. It is determined whether it is large (step S14). That is, since the amount of heat stored in the hot water storage tank 102 is small, it is necessary to circulate and store heat with the heat exchanger 91 for exhaust heat recovery, or it is necessary to circulate hot water to a heating circuit (not shown). If this is the case, it is determined that the heat demand is large (YES in step S14), and the forced reduction control of the output for suppressing the voltage rise is performed not on the fuel cell power generation device FP but on the natural power generation device NP side (step S15). . That is, the output voltage at the inverter unit 22 of the power conditioner 2 on the natural power generator NP side is reduced. Accordingly, if it is detected that the system voltage has decreased below the suppression threshold (YES in step S16), the output on the natural power generator NP side that has been decreased in step S15 is gradually increased while monitoring the system voltage. To return (step S17). Even if the output is reduced in step S15, if it is still greater than or equal to the suppression threshold (NO in step S16), the output on the natural power generator NP side is reduced to the minimum (step S18). In the same manner, while monitoring the system voltage, the output on the natural power generator NP side reduced in step S15 is gradually increased and the process returns (YES in step S19, step S17).

  If the system voltage does not decrease even in the above processing, the forced output reduction is executed not only on the natural power generation device NP side but also on the fuel cell power generation device FP side. That is, when the system voltage has not decreased below the suppression threshold in step S19 (NO in step S19), the output on the fuel cell power generation device FP side is decreased (step S20). By reducing the output at the inverter unit 22 of the power conditioner 2 on the fuel cell power generation device FP side, the controller that controls the operation on the fuel cell power generation device FP side also reduces the power generation amount as the output at the power conditioner 2 decreases. I will let you. As a result, if the system voltage becomes less than the suppression threshold (YES in step S21), the respective outputs on the natural power generation device NP side and the fuel cell power generation device FP side that have been subjected to forced output reduction are monitored while monitoring the system voltage. It is gradually raised and the process returns (YES in step S21, step S22). If the system voltage is greater than or equal to the suppression threshold in step S21 (NO in step S21), the output on the fuel cell power generation device FP side is reduced to the minimum (step S23). While monitoring the system voltage, the outputs on both the natural power generator NP side and the fuel cell power generator FP side are gradually increased and the process returns (YES in step S24, step S22). If the system voltage does not decrease below the suppression threshold even if the output on the fuel cell power generation device FP side is reduced to the minimum (NO in step S24), finally, the interconnection relay unit 23 is opened to connect to the power system 1. The connection is interrupted, and the process returns after waiting for the cancellation of the abnormality (step S25).

  While each of the above processes gives priority to the heat demand on the fuel cell power generation device FP side (YES in step S14) as an exception to the principle processing described later, while satisfying the heat demand on the fuel cell power generation device FP side, In addition, linkage control for realizing voltage rise suppression in cooperation with both the fuel cell power generation device FP side and the natural power generation device NP side is configured.

  On the other hand, when it is not necessary to consider the heat demand on the fuel cell power generation device FP side in step S14 (NO in step S14), as shown in FIG. 6, the voltage rise suppression is suppressed to the fuel cell power generation device FP side and the natural power generation device NP. Linking is performed on both sides to execute linkage control for suppressing fuel consumption required for power generation.

  That is, first, the output on the natural power generator NP side is lowered to a predetermined amount by trial (step S26), and if the system voltage drops below the suppression threshold (YES in step S27), the output on the natural power generator NP side decreases. It is determined whether or not the current output is smaller than the current output on the fuel cell power generation device FP side (step S28), and if it is smaller, the output on the fuel cell power generation device FP side is gradually reduced and the natural power generation device is reduced by the output decrease. The output on the NP side is gradually increased (step S29). Then, while monitoring the system voltage, the outputs on both the natural power generator NP side and the fuel cell power generator FP side are gradually increased and the process returns (step S30). Specifically, for example, if the output on the natural power generation device NP side is lowered by 500 W as a trial, and the current output on the fuel cell power generation device FP side is 800 W, then the fuel cell power generation device FP The output on the side is gradually decreased from 800 W to 300 W, and at the same time, the output on the natural power generator NP side is gradually increased for 500 W, which is reduced to the above test. In other words, from the viewpoint of suppressing fuel consumption, if the output is forcibly reduced, the output on the fuel cell power generation device FP side is basically reduced. In order to test how much it can be lowered to below the suppression threshold, first, the output on the natural power generator NP side where the output can be changed suddenly is reduced (step S26). Then, after confirming that the output voltage is reduced to less than the suppression threshold if the output is reduced by 500 W, the reduction of 500 W is reduced from the reduction process on the natural power generator NP side to the fuel cell power generator FP side. (Steps S28 and S29) to satisfy the suppression of voltage rise while suppressing fuel consumption.

  As a process similar to this, even if the output decrease on the natural power generation device NP side is larger than the current output on the fuel cell power generation device FP side in step S28 (NO in step S28), the fuel cell power generation device FP side While the output is reduced to the minimum, the output on the natural power generation device NP side is gradually increased by the output decrease on the fuel cell power generation device FP side (step S31). Then, while monitoring the system voltage, the outputs on both the natural power generator NP side and the fuel cell power generator FP side are gradually increased and the process returns (step S30). As a specific example in this case, for example, when the output on the natural power generation device NP side is lowered by 1000 W, if the current output on the fuel cell power generation device FP at that time is 800 W, then the fuel cell power generation device FP side The output is gradually decreased from 800 W to 300 W by 500 W, and at the same time, the output on the natural power generator NP side is gradually increased from 500 W to 500 W.

  On the other hand, if the system voltage does not fall below the suppression threshold in the trial output reduction process on the natural power generator NP side in step S26 (NO in step S27), the output on the fuel cell power generator FP side is also reduced (step S32). If the system voltage decreases to less than the suppression threshold (step S33: YES), the output of both the natural power generator NP side and the fuel cell power generator FP side is monitored while monitoring the system voltage, that is, the system voltage. Raise gradually and return. If the system voltage does not drop below the suppression threshold in step S33, the output on the fuel cell power generation device FP side is reduced to the minimum (step S34), and if the system voltage drops below the suppression threshold, the process of step S30 is performed. If it still does not fall below the suppression threshold, the output on the natural power generator NP side is lowered to the minimum (step S36). If the system voltage falls below the suppression threshold, the process proceeds to step S30 (YES in step S37). If not lowered (NO in step S37), the interconnection relay unit 23 is finally opened. The connection with the electric power system 1 is cut off, and after returning from the abnormal state, the process returns (step S38).

  In the case of the above embodiment, when executing the voltage increase suppression control when the system voltage is equal to or higher than the suppression threshold, the voltage increase suppression control is separately executed on both the natural power generation device NP side and the fuel cell power generation device FP side. Instead, fuel consumption can be suppressed by performing basic linkage control in which priority is given to the forced output reduction process on the fuel cell power generation device FP side. On the other hand, when the heat demand in the hot water storage unit 10 associated with the fuel cell power generation device FP is large, the linkage control is performed in consideration of the heat demand, giving priority to the forced output reduction process on the natural power generation device NP side. Thus, the heat demand on the fuel cell power generation device FP side can be satisfied or maintained.

<Other embodiments>
In addition, this invention is not limited to the said embodiment, Various other embodiments are included. That is, in the above embodiment, as shown in FIG. 7A, a control unit 24 including a voltage rise suppression control unit is provided for each power conditioner 2, and a plurality of control units 24 are connected by communication via a communication line 25. However, the present invention is not limited to this. For example, as shown in FIG. 7B, only one of the power conditioners 2 is provided with a control unit 24. The communication line 25 may be used to control not only one of the power conditioners but also the other power conditioner 2a not provided with a control unit. Further, as shown in FIG. 7C, the control of the plurality of power conditioners 2 a and 2 a that are not provided with the control unit may be performed by the communication lines 25 and 25 by the independent control unit 24. .

  The natural power generation device NP of the above embodiment may be configured by a device that generates power using natural energy, such as a wind power generation device or a tidal power generation device, in addition to the solar power generation device. Moreover, in the said embodiment, although the fuel cell power generation device FP was shown as a fuel power generation device which consumes fuel and generates electric power, you may comprise not only this but a gas engine power generation device, for example. Furthermore, as the fuel cell power generation device FP, of course, a power generation device using a fuel cell of a type other than the solid oxide fuel cell may be used.

FP Fuel cell power generator (fuel power generator)
NP natural power generator (solar power generator)
1 Power System 2 Power Conditioner 24 Control Unit (Voltage Increase Suppression Control Unit)
25 Communication line

Claims (7)

A power generation system in which a natural power generation device that generates power using natural energy and a fuel power generation device that generates power by consuming fuel are linked to an electric power system,
A power conditioner provided in the natural power generation device, a power conditioner provided in the fuel power generation device, and a control unit for executing voltage rise suppression control,
When the natural power generation device and the fuel power generation device perform the voltage increase suppression control while the natural power generation device and the fuel power generation device are in simultaneous power generation operation, the control unit depends on the respective characteristics or the current situation of the natural power generation device and the fuel power generation device. The power conditioner is configured to link and control both power conditioners so as to give priority to output voltage suppression processing by the power conditioner on either side of the natural power generator or the fuel power generator, and
When the current state of heat utilization on the fuel power generation device side is a large heat demand when executing the voltage rise suppression control, the output voltage to the power system for the power conditioner on the natural power generation device side that consists of the process of suppression to perform coordinated control to priority,
Power generation system characterized in that. The power generation system according to claim 1,
The control unit is configured to execute linkage control that prioritizes output voltage suppression processing for the power system for a power conditioner on the fuel power generation device side when executing the voltage increase suppression control. The power generation system. The power generation system according to claim 1 or 2 ,
When the control unit prioritizes the output voltage suppression process, the control unit prioritizes the output voltage suppression process on the priority side and / or suppresses the output voltage on the priority side. A power generation system configured to perform a process that makes the amount larger than the other side. The power generation system according to any one of claims 1 to 3 ,
The control unit is provided in each of a power conditioner of the natural power generation device and a power conditioner of the fuel power generation device, and both control units are connected to be communicable with each other to execute the voltage rise suppression control. The power generation system is configured as follows. The power generation system according to any one of claims 1 to 3 ,
The control unit is configured to perform communication control with the power conditioner of the natural power generation device and the power conditioner of the fuel power generation device so as to be able to communicate with each other, and to perform the voltage rise suppression control. , Power generation system. The power generation system according to any one of claims 1 to 5 ,
The power generation system, wherein the natural power generation device is a solar power generation device. The power generation system according to any one of claims 1 to 6 ,
The power generation system, wherein the fuel power generation device is a fuel cell power generation device or a gas engine power generation device.