JP2012138988A - Power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generation system, in which a plurality of kinds of distributed power supplies is linked to a power system, capable of appropriately performing voltage-rise suppression control corresponding to an occurrence state of a system voltage-rise during performing the voltage-rise suppression control.SOLUTION: A natural power generation device (a photovoltaic power generation device) NP and a fuel cell power generation device FP are system-linked to a commercial power system 1. A built-in control section in a power conditioner 2 of each power generation device is connected so as to be mutually communicable with each other via a communication line 25, so that the power conditioners 2, 2 are cooperatively controlled during voltage-rise suppression control. A higher priority is given to the natural power generation device NP side when output power is forced to be lowered. Output power of the fuel cell power generation device FP side is forced to be lowered when a voltage-rise of the power system continues for a long time. When heat storage by heat recovery of the fuel cell power generation device FP is enough, the priority is reversely given as an exception.

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, when multiple types of distributed power supplies perform voltage rise suppression control during simultaneous power generation, the power supply system can be quickly adapted to the situation of the voltage rise. It relates to technology that enables processing.

  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, when there are a plurality of power conditioners, transmission / reception is also performed via a communication line in order to collect each operation data (see, for example, Patent Document 2). And it has also been reported that by performing the voltage rise suppression control as described above, the generated power is wasted in the solar power generation module, resulting in a decrease in power generation efficiency (see, for example, Patent Document 3).

JP 2008-35640 A WO2006 / 075371 Japanese Patent No. 3942400

  By the way, when the system voltage fluctuates and the fluctuation amount exceeds the threshold value on the rising side, the voltage rise suppression control is executed, but power generation is performed by connecting multiple types of distributed power sources with the power system. In the system, when the systematic voltage is individually or individually executed by each distributed power source whenever the system voltage exceeds the threshold, the voltage increase suppression control becomes complicated, or the voltage increase suppression is quick. There is a risk that it may not be possible to achieve the conversion.

  That is, the system voltage varies widely, and even if the voltage rises, it may return to the original normal voltage range in a short period of time, or the voltage rise state may persist for a long period of time. As described above, even if the voltage rise suppression control is performed uniformly for a short-term voltage rise, it becomes complicated or lacks quickness. There is a risk of becoming.

  On the other hand, in the fuel cell power generation, it takes time and labor to start and stop the fuel cell power generation, and there is also a situation that a change in the power generation amount 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. Furthermore, 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, and the heat recovery amount (for example, the amount of stored hot water) is sufficiently stored ( In the fully charged state), if power generation is further continued, a situation in which heat must be dissipated wastefully may occur.

  Therefore, if voltage rise suppression control is performed individually and uniformly 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, a situation that may impair the utilization efficiency of the recovered heat is caused.

  The present invention has been made in view of such circumstances, and an object of the present invention is to perform a voltage rise suppression control in a power generation system in which a plurality of types of distributed power sources are connected to a power system. Another object of the present invention is to provide a power generation system in which appropriate voltage rise suppression control is executed in accordance with the situation of occurrence of system voltage rise.

  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, the control unit performs an output voltage suppression process by a power conditioner on the natural power generation device side. Both power conditioners are linked and controlled to give priority (claim 1).

  Specifically, when the voltage increase suppression control is executed as the control unit, the voltage increase suppression control is set according to the duration of the rising state of the system voltage increase state of the power system that requires the voltage increase suppression control. If the short period is shorter than the time, the output voltage suppression processing for the power system is performed only for the power conditioner on the natural power generator side, while the rising state is maintained over a long period longer than the set time. If it continues, it can be set as the structure which permits the suppression process of the output voltage with respect to the said electric power grid for the power conditioner by the side of the said fuel electric power generating apparatus. For example, until the set time elapses, only the power conditioner on the natural power generator side is targeted for the output voltage suppression process for the power system, while the output voltage suppression process is executed until the set time elapses. However, when it is still necessary to suppress the voltage rise, output voltage suppression processing for the power system is permitted for the power conditioner on the fuel power generation apparatus side.

  In the case of the present invention, when the voltage rise suppression control is executed, priority is given to the suppression process of the output voltage on the natural power generation apparatus side, and thus the voltage rise suppression is required due to the rise of the system voltage of the power system. However, if the voltage rise state is short, the voltage rise suppression control on the natural power generator side will be prioritized. For example, the output voltage on the fuel cell power generator side is reduced although the output voltage on the natural power generator side is reduced. The power generation is continued in the same state without changing the voltage. In this case, the change such as reduction or return of the output voltage on the natural power generation device side can be performed very quickly as compared with the case where the output voltage on the fuel cell power generation device side is reduced, and the output voltage reduction, etc. Since the fuel cell power generation device that can only change the output of the fuel cell generator does not need to change the output voltage, it is possible to process the suppression of the increase in the system voltage with high responsiveness and speed. Moreover, it is possible to avoid the trouble of repeating the voltage increase suppression control uniformly for both the natural power generation device side and the fuel cell power generation device side each time the system voltage of the power system increases.

  In the power generation system of the present invention, the fuel cell power generation device includes a heat storage unit that recovers and stores exhaust heat generated by power generation, while the control unit executes an exception process in the voltage rise suppression control. It is also possible to provide an exception handling unit. In this case, when the voltage rise suppression control is executed as the exception processing unit, if the current heat storage state by the heat storage unit is a full storage state in the heat recovery state on the fuel power generation device side, the natural power generation device Cancel the priority execution of the suppression process of the output voltage for the power system intended for the power conditioner on the side, and instead, the suppression process of the output voltage for the power system for the power conditioner on the fuel generator side It can be set as the structure which performs linkage control which gives priority to (Claim 3).

  By doing so, the following action is obtained. That is, when the fuel cell power generation device side is in the fully stored state, it is not necessary to maintain the output voltage on the fuel cell power generation device side in the normal power generation state from the viewpoint of heat recovery. If it is left, the heat radiation operation must be carried out, and the heat storage must be discharged wastefully. Therefore, in such a situation, the exception processing unit as an exception to the basic process of giving priority to the suppression process of the output voltage on the natural power generator side, such as first reducing the output only on the natural power generator side By executing the exception processing, both improvement of heat recovery efficiency and suppression of voltage rise of the system voltage can be satisfied without continuing waste of heat recovery on the fuel cell power generation device side.

  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 of increasing the amount of suppression of the above is greater than that on the other side. By doing so, it is possible to reliably realize suppression of voltage rise while obtaining the effect of priority.

  In addition, it can be set as a solar power generation device as a natural power generation device in this invention (Claim 5).

  As described above, according to the power generation system of the present invention, when the voltage increase suppression control is executed, priority is given to the suppression process of the output voltage on the natural power generator side, so that the system voltage of the power system increases. If it is necessary to suppress the voltage rise, if the voltage rise state is short, the output voltage on the fuel cell power generator side is the same without changing the output voltage on the natural power generator side, for example. It will be possible to continue power generation. For this reason, the change such as reduction or return of the output voltage on the natural power generation device side can be performed very quickly as compared with the case where the output voltage on the fuel cell power generation device side is reduced, etc. Since the fuel cell power generation apparatus that can only change the output of the fuel cell generator does not need to change the output voltage, the voltage rise suppression of the system voltage can be processed with extremely responsiveness and speed. In addition, it is possible to avoid the trouble of repeating the voltage increase suppression control uniformly for both the natural power generation device side and the fuel cell power generation device side each time the system voltage of the power system increases.

  In particular, according to claim 3, when the heat storage state on the fuel cell power generation device side is in the full storage state, priority is given to the suppression processing of the output voltage on the natural power generation device side, such as first reducing the output only on the natural power generation device side. As an exception to basic processing, by executing exception processing by the exception processing unit, without continuing waste of heat recovery on the fuel cell power generator side, improvement of heat recovery efficiency and suppression of system voltage increase Both can be satisfied.

  According to the fourth aspect of the present invention, when giving priority to the suppression process of the output voltage, the process of suppressing the output voltage on the priority side is prior to the other side, and / or the output voltage of the priority side is suppressed. 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 5, it can be specifically specified as a natural power generator in the present 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 1st part of the flowchart of the voltage rise suppression control with which the control part of each power conditioner is provided. It is a 2nd part of the flowchart of the voltage rise suppression control with which the control part of each power conditioner is provided. It is a 3rd part of the flowchart of the voltage rise suppression control with which the control part of each power conditioner is provided. FIG. 8A is a time chart showing the relationship between the fluctuation of the system voltage and the voltage output of the natural power generator and the voltage output of the fuel power generator. FIG. 8A is a time chart when the voltage rise fluctuation is short-term, FIG. b) is a time chart when the voltage rise fluctuation is for a long time. FIG. 9A is an enlarged explanatory view of a part A in FIG. 8B, and FIG. 9B is a graph showing fluctuations in the system voltage and natural variations in exception processing executed when the exceptional situation in FIG. 6 occurs. It is a time chart which shows the relationship between the voltage output of a power generator, and the voltage output of a fuel power generator. FIG. 10A shows the relationship between the voltage rise suppression control unit and a plurality of power conditioners. FIG. 10A shows the case where the control unit (voltage rise suppression control unit) is provided in each power conditioner. FIG. 10B shows a case where a control unit (voltage rise suppression control unit) is provided in any one power conditioner, and the other power conditioner is controlled by this one control unit. FIG. 10C 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, so 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. Water that is circulated and supplied to the heat exchanger is heated by heat exchange.

  Hot water heated and heated by heat exchange in the heat exchanger 91 for exhaust heat recovery is returned to and stored in the hot water storage tank 102 as a heat storage unit. 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. In addition, if the amount of heat stored in the hot water storage tank 102 (the amount of hot water stored above a predetermined temperature) reaches a fully stored state, heat recovery becomes impossible in that state, and therefore the cooling radiator 104 is used to perform further heat recovery. After the hot water is radiated, the heat recovery heat exchanger 91 is sent.

  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.

  In the voltage increase suppression control by the voltage increase suppression control unit, each distributed power source (natural power generator NP or fuel cell power generator FP) is detected when a voltage increase is detected such that the system voltage exceeds a predetermined threshold (for example, less than 107 V). ) Side output voltage is lowered, and output control is performed by the inverter unit 22 of the power conditioner 2 in particular so that it becomes lower than the voltage value on the system power side at that time. In the detection of the voltage increase, when the average system voltage for a predetermined time (for example, 30 seconds) exceeds the threshold, the voltage increase detection is confirmed and voltage increase suppression control described later is started. ing.

  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 a voltage increase exceeding the threshold voltage is detected, the two control units 24 and 24 perform voltage increase suppressing 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 to 7 show examples of the voltage rise suppression control, and the contents of the voltage rise suppression control will be described with reference to these.

  Whether or not the fuel cell power generation device FP and the natural power generation device NP both perform normal power generation operation (step S11), for example, whether the average system voltage for 30 seconds is less than a threshold value (suppression threshold value; for example, 107V) to be suppressed. Are continuously monitored (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), after confirming that no exceptional situation (described later) has occurred (NO in step S14), the voltage rises. Start suppression control. When the control is started, the timer count is started. First, forcibly lowering the output for suppressing voltage rise is performed not on the fuel cell power generator FP but on the natural power generator 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 by a predetermined unit. As long as the system voltage exceeds the suppression threshold (NO in step S16), the reduction process for one unit is repeated until the timer value reaches the set time tp (NO in step S17, step S15). In this process, 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. Then, the process returns (step S18). For example, 3 to 30 minutes is set as the set time tp.

  As shown in FIG. 8 (a), when the system voltage exceeds the suppression threshold (see timing T1 in FIG. 8), the decrease of the output voltage on the natural power generator NP side is started, and only on this natural power generator NP side. If the increase in the system voltage is such that the system voltage returns (decreases) to less than the suppression threshold before the set time tp elapses due to the decrease in the output voltage of the natural power generation apparatus NP, The power generation is continued in the same state without changing the output voltage on the fuel cell power generation device FP side only by the voltage rise suppression control. In this case, the change such as reduction or return of the output voltage on the natural power generation device NP side can be performed very quickly as compared with the case where the output voltage on the fuel cell power generation device FP side is reduced, and the output voltage can be reduced. Since the fuel cell power generation device FP that can only be changed at a low speed, such as a decrease, does not need to change the output voltage, the suppression of the increase in the system voltage can be processed with high responsiveness and speed. Become.

  Even if the output voltage on the natural power generation device NP side in step S15 is repeatedly reduced by one unit, if the set time tp elapses while the system voltage exceeds the suppression threshold (YES in step S17), That is, when the system voltage rise continues beyond the set time tp for a long time, the output voltage lowering process on the natural power generator NP side is stopped, while the power conditioner 2 on the fuel cell power generator FP side is stopped. The process for forcibly lowering the output voltage in the inverter unit 22 is started (step S19). In short, if the system voltage becomes a voltage increase state over a long period of time, in addition to the output voltage decrease process on the natural power generation device NP side, for the first time, the forced output decrease is also performed on the fuel cell power generation device FP side. Start it. In other words, after confirming that the system voltage rise is not temporary, execution of forced output reduction on the fuel cell power generation device FP side is started.

  That is, 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 performs the operation control on the fuel cell power generation device FP side also generates power as the output at the power conditioner 2 decreases. Will be reduced. By reducing the output voltage on the fuel cell power generation device FP side (step S19), if the system voltage falls below the suppression threshold (YES in step S20 in FIG. 6), the system voltage is monitored in step S15. The reduced output on the natural power generator NP side is first increased, and then the output on the fuel cell power generator FP side reduced in step S19 is gradually increased, and the process returns (step S21). On the other hand, if the system voltage still exceeds the suppression threshold in step S20 (NO in step S20), the output on the natural power generator NP side is reduced to the minimum (step S22). Similarly, while monitoring the system voltage, the output on the natural power generator NP side and the output on the fuel cell power generator FP side are gradually increased and the process returns (YES in step S23, step S21).

  Regarding the situation of the voltage rise suppression control in the case where the voltage rise of the above system voltage extends over a long period of time, referring to FIG. 8B, when the system voltage exceeds the suppression threshold (see timing T1), The output voltage on the natural power generator NP side is forcibly lowered until the set time tp elapses. When the set time tp elapses (see timing T2), the decrease in the output voltage on the natural power generator NP side is stopped, instead. The reduction of the output voltage on the fuel cell power generator FP side is started. If the system voltage falls below the suppression threshold (see timing T3), the reduction of the output voltage on the fuel cell power generation device FP side is stopped, the output on the natural power generation device NP side is increased, and the output voltage on the natural power generation device NP side becomes When the original state is restored (see timing T4), the output voltage on the fuel cell power generation device FP side is increased. Note that the output voltage of the natural power generator NP is decreased by a predetermined unit until the set time tp elapses, and it is determined whether or not the system voltage has decreased below the suppression threshold. As shown in FIG. 9 (a), in order to take an average value of a predetermined time tv (for example, 30 seconds) to determine whether or not the system voltage has fallen below the suppression threshold, the output voltage is waited for the predetermined time tv. Is repeatedly reduced by a predetermined unit.

  If the system voltage does not yet fall below the suppression threshold value in step S23, the output voltage on the natural power generator NP side where the reduction process is temporarily stopped in step S19 is reduced to the minimum (step S26). Before that, whether or not the fuel cell power generation device FP, which has been reduced to the minimum output in step S22, is more efficient in terms of reducing the utility cost, that is, whether the fuel cell power generation device FP has been completely stopped, that is, It is determined whether or not the stop condition is satisfied (step S24), and if not satisfied, the natural power generator NP side is limited to the minimum output while the fuel cell power generator FP side is continuously operated with the minimum output (step S24). NO in step S24, step S26), if established, the fuel cell power generation device FP side is completely stopped (YES in step S24, step S25), and the natural power generation device NP side is reduced to the minimum output (step S26). . The establishment of the stop condition means that the amount of heat stored in the hot water storage tank 102 (see FIG. 2) (the amount of hot water stored above a predetermined temperature) is sufficient or above a predetermined amount, and therefore heat recovery at the fuel cell power generator FP. The current efficiency calculated from the built-in electronic clock belongs to the morning time zone, so the amount of sunlight increases and the power generation output of the natural power generator NP increases. In addition, it is established that the amount of hot water used is less than that in the afternoon (night). This is because, when such a stop condition is satisfied, it is possible to reduce the utility cost by stopping the fuel cell power generation device FP completely, rather than continuing the operation with the minimum output.

  If the system voltage becomes less than the suppression threshold as described above, the process returns via step S21 (YES in step S27). If the system voltage is still higher than the suppression threshold, that is, if the system voltage does not fall below the suppression threshold (step S27). Finally, the connection relay unit 23 is opened to disconnect the connection with the power system 1 (system disconnection), and after returning from the abnormality, the process returns (step S28).

  Each of the above processes is a basic process of the present invention. Next, an exceptional process when there is an exceptional situation in step S14 in FIG. 5 will be described with reference to FIG. As an exception to the principle processing, when the heat storage amount on the fuel cell power generation device FP side is in a fully stored state, the output voltage on the fuel cell power generation device FP side is maintained in a normal power generation state from the viewpoint of heat recovery. It is not necessary, but rather if it is maintained, the radiator 104 (see FIG. 2) must be dissipated and the stored heat must be discharged wastefully. It is determined that there is a situation (exception situation) in which an exceptional process of the basic process of lowering the output of only the power generation device NP side is first executed (YES in step S14), and voltage suppression control based on the following exception process is executed. To do. Thereby, both improvement of heat recovery efficiency and suppression of voltage rise of the system voltage can be satisfied without continuing waste of heat recovery on the fuel cell power generation device FP side.

  That is, first, the output voltage on the fuel cell power generation device FP side is forcibly lowered (step S29 in FIG. 7), and if the system voltage falls below the suppression threshold (YES in step S30), the fuel is monitored while monitoring the system voltage. The output voltage on the battery power generation device FP side is increased and the process returns (step S33). If the system voltage still exceeds the suppression threshold (NO in step S30), the output voltage on the fuel cell power generation device FP side is reduced to the minimum (step S31). As a result, if the system voltage becomes less than the suppression threshold (YES in step S32), the process of step 33 is performed. If the suppression threshold is still exceeded (NO in step S32), this time the natural power generator NP side The output voltage is forcibly reduced (step S36). At that time, similarly to the processing of steps S24 and S25, it is determined whether or not it is better to completely stop the operation of the fuel cell power generation device FP (determination of whether or not the stop condition is satisfied; step S34). If the stop condition is satisfied, the power generation operation on the fuel cell power generation device FP side is completely stopped (step S35).

  If the system voltage drops below the suppression threshold by reducing the output voltage on the natural power generator NP side (YES in step S37), the natural power generator NP side is first raised while monitoring the system voltage, and then fuel cell power generation The apparatus FP side is raised to recover (step S38). If the system voltage does not decrease below the suppression threshold even if the output voltage on the natural power generator NP side is decreased by a predetermined amount (NO in step S37), the output voltage on the natural power generator NP side is reduced to the minimum (step S39). If the system voltage becomes less than the suppression threshold (YES in step S40), the process of step S38 is performed. If the system voltage still exceeds the suppression threshold, system disconnection is performed to cancel the abnormality. Wait (step S41). The above-described determination in step S14 and steps S29 to S41 shown in FIG. 7 constitute an exception processing unit.

  As shown in FIG. 9 (b), the above exception processing situation is such that if the system voltage exceeds the suppression threshold (see timing T1), the output on the natural power generator NP side is not lowered, and the fuel cell power generator FP side is not reduced. Reduce output. If the system voltage does not fall below the suppression threshold even if the output on the fuel cell power generation device FP side is reduced to the minimum (see timing T5), the output on the natural power generation device NP side is then lowered, thereby suppressing the system voltage. If it falls below the threshold (see timing T6), the output on the natural power generator NP side is increased, and if it is restored to the original output (see timing T7), the output on the fuel cell power generator FP side is increased.

<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. 10A, 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. 10B, only one of the power conditioners 2 is provided with a control unit 24, and the control unit 24 allows the above-described control to be performed. 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. 10C, the control of the plurality of power conditioners 2a and 2a that are not provided with the control unit may be performed by the communication lines 25 and 25 by the independent control unit 24, respectively. .

  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)
102 Hot water storage tank (heat storage part)

Claims (5)

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,
The control unit prioritizes output voltage suppression processing by a power conditioner on the natural power generation device side when the natural power generation device and the fuel power generation device execute the voltage increase suppression control during simultaneous power generation operation. So that both inverters are linked and controlled,
A power generation system characterized by that. The power generation system according to claim 1,
The control unit, when executing the voltage increase suppression control, the short-term shorter than the set time according to the length of the duration of the rising state of the system voltage of the power system that requires the voltage increase suppression control In the meantime, only the power conditioner on the natural power generator side is subjected to the suppression process of the output voltage for the power system, while the fuel continues if the rising state continues for a long period longer than a set time. A power generation system configured to permit an output voltage suppression process for the power system for a power conditioner on a power generation device side. The power generation system according to claim 1 or 2,
The fuel cell power generation device includes a heat storage unit that collects and stores exhaust heat associated with power generation, while the control unit includes an exception processing unit that executes exception processing in the voltage rise suppression control,
When the exception processing unit performs the voltage increase suppression control, if the current heat storage state by the heat storage unit is a fully stored state in the heat recovery state on the fuel power generation device side, the power on the natural power generation device side Cancel the priority execution of the output voltage suppression process for the power system intended for the conditioner, and instead give priority to the output voltage suppression process for the power system for the power conditioner on the fuel generator side. A power generation system configured to perform linkage control. The power generation system according to claim 1,
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 4,
The power generation system, wherein the natural power generation device is a solar power generation device.

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