Power generation system and control device

Abstract

To provide a power generation system which can prevent an inverse load flow while deterioration of energy efficiency is suppressed.SOLUTION: A power generation system includes: a power generation part for supplying power to a load based on a prescribed power generation output setting value; a measurement part for measuring power reception point power including power or current at a power reception point of power supplied from a commercial power system to the load; a margin setting part for calculating an inverse load flow prevention margin of power generation output of the power generation part for suppressing a flow of power or current from the power generation part to the commercial power system based on a power reception point power deviation obtained from a difference between power reception point power and a power reception point power average being a time average of power reception point power; and a power generation output setting part for setting the power generation output setting value based on the power reception point power average and the inverse load flow prevention margin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a power generation system capable of operating in a grid-connected manner, and a control device. [Background technology]

[0002] The use of power generation systems using renewable energy is expanding due to changes in social conditions such as growing interest in the SDGs and rising energy resource prices. However, there are various challenges when interconnecting a power generation system using renewable energy with an existing commercial grid.

[0003] For example, it is difficult to freely control the power output of photovoltaic power generation devices and wind power generation devices. When such a power generation system, whose power output is difficult to control, is connected to a commercial grid, an increase in power output may cause a reverse power flow into the commercial grid. From the viewpoint of the stability of the commercial grid, the reverse power flow of generated power to the grid is prohibited by grid interconnection regulations and contracts with electric power companies. Similarly, power generation restrictions based on time periods are imposed on power generation systems whose power output is difficult to control.

[0004] To prevent reverse power flow, for example, a technology has been proposed that operates auxiliary equipment (such as heaters) in the power generation system or an external load to suppress the power transmitted from the power generation system to the commercial grid. However, such a technology has the problem that the surplus power in the power generation system is supplied to auxiliary equipment and loads that do not actually need it, resulting in a waste of energy. In other words, the energy efficiency has deteriorated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2009-64753 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, conventional power generation systems and control devices have a problem in that energy efficiency is deteriorated in order to prevent reverse power flow. An object of the present invention is to provide a power generation system and control device that can prevent reverse power flow while suppressing deterioration of energy efficiency. [Means for solving the problem]

[0007] A power generation system according to an embodiment is a power generation system that is interconnected with a commercial power system and supplies power to a load. The power generation system according to the embodiment includes a power generation unit that supplies power to the load based on a predetermined power generation output set value, a measurement unit that measures a power receiving point power including power or current at a power receiving point of power supplied from the commercial power system to the load, a margin setting unit that calculates a reverse power flow prevention margin of a power generation output of the power generation unit that suppresses a flow of power or current from the power generation unit to the commercial power system based on a power receiving point power deviation obtained from a difference between the power receiving point power and a power receiving point power average that is a time average of the power receiving point power, and a power generation output setting unit that sets a power generation output set value based on the power receiving point power average and the reverse power flow prevention margin. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a configuration of a power generation system according to a first embodiment. [Diagram 2] 1 is a block diagram showing a configuration of a control device of a power generation system according to a first embodiment. [Diagram 3] FIG. 4 is a diagram showing an example of the relationship between the deviation of the power at the receiving point from the commercial grid from its average value and the reverse power flow prevention margin in the power generation system according to the first embodiment. [Figure 4] FIG. 11 is a diagram showing another example of the relationship between the deviation of the power at the receiving point from the commercial grid from its average value and the reverse power flow prevention margin in the power generation system according to the first embodiment. [Diagram 5] FIG. 11 is a diagram showing another example of the relationship between the deviation of the power at the receiving point from the commercial grid from its average value and the reverse power flow prevention margin in the power generation system according to the first embodiment. [Figure 6] 4 is a flowchart showing the operation of the control device of the power generation system of the first embodiment. [Figure 7] 5 is a diagram showing an example of a change in power receiving point power deviation and a change in power generation output when a reverse power flow prevention margin is changed accordingly in the control device of the first embodiment. FIG. [Figure 8] 10 is a diagram showing another example of a change in power receiving point power deviation and a change in power generation output when the reverse power flow prevention margin is changed accordingly in the control device of the first embodiment. FIG. [Figure 9] 10 is a flowchart showing the operation of a control device in a power generation system according to a second embodiment. [Figure 10] FIG. 11 is a diagram illustrating a predetermined time for calculating the power receiving point average power in the control device of the power generation system according to the second embodiment. [Figure 11] FIG. 11 is a block diagram showing the configuration of a control device of a power generation system according to a third embodiment. [Figure 12] FIG. 11 is a diagram showing an example of a relationship between a predicted value of power receiving point power and a reverse power flow prevention margin in a power generation system according to a third embodiment. [Figure 13] FIG. 11 is a diagram showing another example of the relationship between the predicted value of the power receiving point power and the reverse power flow prevention margin in the power generation system according to the third embodiment. [Figure 14] FIG. 11 is a diagram showing another example of the relationship between the predicted value of the power receiving point power and the reverse power flow prevention margin in the power generation system according to the third embodiment. [Figure 15] FIG. 11 is a diagram showing an example of a change in power receiving point power and power output over time in one day in the power generation system according to the third embodiment. [Figure 16] FIG. 13 is a block diagram showing the configuration of a power generation system according to a fourth embodiment. [Figure 17] FIG. 13 is a block diagram showing the configuration of a control device for a power generation system according to a fourth embodiment. [Figure 18] FIG. 13 is a block diagram showing the configuration of a power generation system according to a fifth embodiment. [Figure 19]FIG. 13 is a block diagram showing the configuration of a control device of a power generation system according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) A power generation system according to a first embodiment of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a block diagram showing the configuration of the power generation system according to the first embodiment.

[0010] 1, the power generation system 1 of this embodiment includes a control device 10, a power conditioning system (PCS) 20, a power receiving point power meter 30, a fuel cell 40, and an interconnection breaker 50. The power generation system 1 of this embodiment is connected to a commercial power system 5 and a load 6.

[0011] The power generation system 1 is a power supply source capable of outputting electric power generated by the fuel cell 40. The power generation system 1 can supply output power to a load 6. The power generation system 1 is connected so as to be interconnected with a commercial power grid 5. In other words, when the output power of the power generation system 1 is insufficient, the load 6 can receive power from the commercial power grid 5.

[0012] The commercial power system 5 is a power supply source capable of supplying power mainly generated by a power company. The load 6 is a supply target of the power source supplied by the power generation system 1 of the embodiment. The load 6 is, for example, a device owned by a power consumer.

[0013] The control device 10 is a controller that controls the power generation output in the power generation system 1. The control device 10 can be realized, for example, by a computer device equipped with a CPU (central processing unit) and a memory (not shown). The control device 10 controls the PCS 20, the grid breaker 50, etc. based on a signal (power signal) received from the power receiving point power meter 30.

[0014] The control device 10 has a function of judging whether the output power of the power generation system 1 is in a reverse flow state where it flows out to the commercial power system 5, or in a smooth flow state where power received from the commercial power system 5 is supplied to the load 6, based on the power signal received from the power receiving point power meter 30. Based on the judgment result, the control device 10 can execute output control such as controlling the PCS 20 to stop power generation, or controlling the interconnection breaker 50 to disconnect the power generation system 1 from the commercial power system 5.

[0015] The PCS 20 is a converter capable of converting the voltage and frequency of the power generated by the fuel cell 40 into a predetermined voltage value and frequency. The PCS 20 can convert the DC voltage generated by the fuel cell 40 into an AC voltage. The PCS 20 is connected to the fuel cell 40 and the load 6, and supplies the power generated by the fuel cell 40 to the load 6. That is, the PCS 20 can function as a power generation unit of the power generation system 1 together with the fuel cell 40. The PCS 20 is connected to the commercial power system 5 via the interconnection breaker 50 and the power receiving point power meter 30. That is, the power generation system 1 having the fuel cell 40 and the commercial power system 5 are connected so as to be interconnectable.

[0016] The power receiving point power meter 30 is a power meter (measurement unit) disposed at a power receiving point where the power generation system 1 receives power from the commercial power system 5. The power receiving point power meter 30 can measure not only the power of the normal flow received from the commercial power system 5, but also the power of the reverse flow from the power generation system 1 to the commercial power system 5. That is, the power receiving point power meter 30 can measure both positive and negative power, and can determine whether the state is a normal flow state or a reverse flow state based on the positive and negative values. The power receiving point power meter 30 transmits a power signal indicating the measured power at the power receiving point (power receiving point power) to the control device 10. Here, the power signal may be an analog signal indicating a power value or a digital signal. Note that the power receiving point power meter 30 can be replaced by an ammeter because it enables the determination of reverse flow and normal flow based on the current flow direction. That is, the power signal can be a signal indicating power or a signal indicating current.

[0017] The fuel cell 40 is an electrochemical cell that generates electrical power using a chemical reaction between a fuel, such as hydrogen, and an oxidant, such as oxygen. The fuel cell 40 may supply the generated electrical power to the load 6 through the PCS 20.

[0018] The grid-connection breaker 50 is a breaker capable of disconnecting the connection between the PCS 20 and the power receiving point power meter 30. In the example shown in FIG. 1, the grid-connection breaker 50 is disposed between the PCS 20 and the load 6 and the power receiving point power meter 30. That is, the grid-connection breaker 50 can connect and disconnect (open) the PCS 20 and the load 6 and the power receiving point power meter 30. The grid-connection breaker 50 can receive a control signal from the control device 10. The grid-connection breaker 50 can cut and open the connection between the PCS 20 and the load 6 and the power receiving point power meter 30 based on the control signal from the control device 10. That is, the grid-connection breaker 50 can disconnect the connection between the power generation system 10 and the commercial power system 5.

[0019] Next, the functional configuration of the control device 10 will be described in detail with reference to FIG.

[0020] As shown in FIG. 2, the control device 10 of this embodiment includes a power signal receiving unit 100, a reverse power flow determining unit 110, a circuit breaker control unit 180, a margin control unit 120, a power generation output setting unit 130, and a storage unit 140.

[0021] The power signal receiving unit 100 is connected to the power receiving point power meter 30. The power signal receiving unit 100 is a functional unit that receives a power signal transmitted by the power receiving point power meter 30. The power signal receiving unit 100 passes the power receiving point power indicated by the received power signal to the backflow determination unit 110.

[0022] The reverse power flow determination unit 110 is a functional unit that determines whether or not the power generation system 1 is in a reverse power flow state with respect to the commercial power system 5 based on the power receiving point power. When the power receiving point power meter 30 measures the power received from the commercial power system 5 as positive, if the received power is negative, it is reverse flow power. In other words, the reverse power flow determination unit 110 can determine whether or not the power generation system 1 is in a reverse power flow state based on the power signal.

[0023] The circuit breaker control unit 180 is a functional unit that controls the grid-connection circuit breaker 50. When the determination result of the reverse power flow determination unit 110 is reverse power flow, the circuit breaker control unit 180 transmits a control signal to the grid-connection circuit breaker 50 to shut off the grid-connection circuit breaker 50. The circuit breaker control unit 180 functions as an output control unit that stops the power generation output of the power generation system 1.

[0024] The margin setting unit 120 is a functional unit that sets a margin of the power generation output of the power generation system 1. In the power generation system 1, when the load of the load 6 fluctuates and its power consumption decreases, the surplus power of the power generation system 1 flows out to the commercial power grid 5. That is, the power generation system 1 enters a reverse power flow state. Therefore, the margin setting unit 120 sets a certain amount of margin (reverse power flow prevention margin) that takes into account the load fluctuation.

[0025] Specifically, the margin setting unit 120 increases or decreases the reverse flow prevention margin based on the amount of change in the power at the power receiving point instead of the load fluctuation. The reverse flow prevention margin is used when setting the power generation output of the PCS 20. Therefore, an increase or decrease in the reverse flow prevention margin affects the power generation output.

[0026] The power generation output setting unit 130 is a functional unit that sets the power generation output of the PCS 20. The power generation output setting unit 130 specifies the power generation output based on the power receiving point power and the reverse power flow prevention margin. The power generation output setting unit 130 transmits the specified power generation output as a command signal to the PCS 20. Here, the set value of the power generation output (power generation output set value) sent to the PCS 20 is determined by the following formula. Power output setting value = Average power at receiving point - Reverse power flow prevention margin (1) Here, the power receiving point average (value) is the average (value) of the power receiving point power in a predetermined time unit. That is, the power generation output setting unit 130 is determined based on the difference between the time average of the power receiving point power measured by the power receiving point power meter 30 and the reverse flow prevention margin that guarantees fluctuations in the power receiving point power based on fluctuations in the load. The larger the reverse flow prevention margin, the smaller the power generation output setting value, making it possible to reliably prevent a reverse flow state in the power generation system 1. On the other hand, the smaller the reverse flow prevention margin, the larger the power generation output setting value, making it possible to improve the power generation efficiency of the power generation system 1. The power generation output setting unit 130 also functions as an output control unit that stops the power generation output of the power generation system 1.

[0027] The storage unit 140 is a memory unit that stores various parameters used in the control device 10. The storage unit 140 stores parameters such as the value of the power receiving point power included in the power signal, the power receiving point power average value, the difference between the power receiving point power and the power receiving point power average (power receiving point power deviation), a reverse power flow prevention margin, and power generation output. The parameters stored in the storage unit 140 are referenced by each functional unit constituting the control device 10.

[0028] (Function of margin setting section and reverse power flow prevention margin) The reverse flow prevention margin is a set value that absorbs fluctuations in the load 6 that may cause a reverse flow state in the power generation system 1. When there is a margin in the power generation output by the PCS 20 and the load on the load 6 decreases significantly, the power generation output of the power generation system 1 is likely to become excessive. In other words, the power generation system 1 is likely to enter a reverse flow state. If the fluctuation range of the load on the load 6 is large, the fluctuation in the power at the receiving point also becomes large, increasing the possibility of a reverse flow state.

[0029] The power generation system 1 of this embodiment prevents the power generation output from becoming excessive by increasing or decreasing the reverse flow prevention margin, thereby preventing a reverse flow state. Specifically, when the deviation in the power receiving point power is small, the margin setting unit 120 sets the reverse flow prevention margin to a small value. This allows the PCS 20 to increase the power generation output (power generation amount), thereby making it possible to increase the operation rate of the power generation system 1 and improve the facility operation rate. On the other hand, when the deviation in the power receiving point power is large, the margin setting unit 120 sets the reverse flow prevention margin to a large value. This allows the PCS 20 to reliably prevent the occurrence of reverse flow.

[0030] Fig. 3 shows an example of the relationship between the deviation between the receiving point power from the commercial grid and the receiving point power average, which is its time average (hereinafter referred to as "receiving point power deviation"), and the reverse flow prevention margin M. In the example shown in Fig. 3, the reverse flow prevention margin M is obtained using a function f(ΔP) of the receiving point power deviation ΔP instead of the load fluctuation amount of the load 6. In other words, by setting the relationship between the receiving point power deviation and the reverse flow prevention margin as an increasing linear function f(ΔP), the margin setting unit 120 can obtain the reverse flow prevention margin using this function.

[0031] Fig. 4 shows another example of the relationship between the power deviation at the receiving point and the reverse power flow prevention margin. In the example shown in Fig. 4, the relationship between the power deviation at the receiving point ΔP and the reverse power flow prevention margin M is expressed by an increasing quadratic function g(ΔP).

[0032] Fig. 5 shows yet another example of the relationship between the receiving point power deviation and the reverse flow prevention margin. In the example shown in Fig. 5, the relationship between the receiving point power deviation ΔP and the reverse flow prevention margin M is expressed by an increasing stepped function h(ΔP). In other words, the reverse flow prevention margin does not have to take continuous values ​​as the receiving point power deviation increases or decreases. Similarly, the reverse flow prevention margin may be defined by a discrete function. In this case, digital processing becomes easier.

[0033] In this way, as long as the reverse flow prevention margin tends to expand (increase) as the overall power receiving point power deviation increases, an appropriate function can be adopted depending on the characteristics of the load fluctuations of load 6.

[0034] (Operation of the control device 10 of the first embodiment) Next, the operation of the control device 10 of the first embodiment will be described in detail with reference to Fig. 6 to Fig. 8. Fig. 6 is a flowchart showing an example of the operation of the control device 10 of the first embodiment. Fig. 7 is a diagram showing an example of a change in the power receiving point power deviation in the control device 10 of the first embodiment and a change in the power generation output when the reverse power flow prevention margin is changed accordingly. Fig. 8 is a diagram showing another example of a change in the power receiving point power deviation in the control device 10 of the first embodiment and a change in the power generation output when the reverse power flow prevention margin is changed accordingly.

[0035] The power generation output setting unit 130 specifies an initial set power generation output value and an initial set reverse power flow prevention margin value, and transmits a power generation start signal to the PCS 20 (S200). The PCS 20 that receives the power generation start signal outputs a predetermined power generation output to the load 6 based on the power generated by the fuel cell 40.

[0036] The power signal receiving unit 100 receives the power signal indicating the power receiving point power transmitted by the power receiving point power meter 30 (S205).

[0037] The reverse power flow determination unit 110 determines whether the power generation system 1 is in a reverse power flow state based on the polarity (positive or negative) of the power at the receiving point (S210). Here, if the polarity of the power at the receiving point is positive, it is a forward power flow, and if it is negative, it is a reverse power flow.

[0038] If the determination result shows that the power generation system 1 is in a reverse power flow state (Yes in S210), the circuit breaker control unit 180 transmits a shutoff control signal to the interconnection circuit breaker 50 (S215). This opens the interconnection circuit breaker 50. At this time, instead of transmitting the shutoff control signal, the power generation output setting unit 150 may transmit a power generation stop signal to the PCS 20. The circuit breaker control unit 180 and the power generation output setting unit 150 may transmit a shutoff control signal and a power generation stop signal to the interconnection circuit breaker 50 and the PCS 20, respectively. This stops the power generation output from the power generation system 1 to the commercial power grid 5 (output control).

[0039] If the power generation system 1 is not in a reverse flow state (No in S210), the power signal receiving unit 100 stores the power receiving point power indicated by the received power signal in the storage unit 140 (S220).

[0040] If the predetermined timing has not been reached (the predetermined period has not elapsed) (No in S225), the processes of receiving a power signal (power at the power receiving point), determining whether there is a reverse power flow, and storing the power at the power receiving point are repeated (S205 to S220).

[0041] When a predetermined timing is reached (a predetermined period has elapsed) (Yes in S225), the margin setting unit 120 calculates an average value of the power receiving point power based on the power receiving point power stored in the storage unit 140 (S230). For example, at time t1 in FIG. 7, the margin setting unit 120 reads out the power receiving point power corresponding to the period from time t0 to time t1 (predetermined period) from the storage unit 140 and calculates the time average. The calculated average value of the power receiving point power (power receiving point power average) is stored in the storage unit 140.

[0042] Next, the margin setting unit 120 calculates the absolute value of the difference between the latest (current time) power receiving point power from the storage unit 140 and the latest (last stored in the storage unit 140) power receiving point average (hereinafter referred to as the "power receiving point power deviation") (S235). The calculated power receiving point power deviation is stored in the storage unit 140 together with information indicating the time. For example, within a predetermined period from time t1 to time t2 in Fig. 7, the absolute value of the difference between the power receiving point power at that time and the power receiving point power average for the predetermined period from time t0 to time t1 stored in the storage unit 140 at time t1 is calculated as the power receiving point power deviation.

[0043] Margin setting unit 120 calculates a new reverse power flow prevention margin M using the new power receiving point power deviation ΔP based on the function of the power receiving point power deviation ΔP illustrated in Figures 3 to 5 (S240). At this time, if the calculated power receiving point power deviation ΔP is smaller than the power receiving point power deviation in the previous specified period (for example, from time t0 to time t1), the reverse power flow prevention margin decreases. On the other hand, if the calculated power receiving point power ΔP is larger than the power receiving point power deviation in the previous specified period, the reverse power flow prevention margin increases.

[0044] 7, the power receiving point power deviation in a predetermined period from time t1 to time t2 is smaller than the power receiving point power deviation from time t0 to time t1. As a result, the reverse flow prevention margin newly set at time t2 is smaller than the reverse flow prevention margin at time t1.

[0045] 8, the power receiving point power deviation in a predetermined period from time t6 to time t7 is larger than the power receiving point power deviation from time t5 to time t6. As a result, the reverse flow prevention margin newly set at time t7 is larger than the reverse flow prevention margin at time t6.

[0046] The power generation output setting unit 130 applies the calculated reverse power flow prevention margin to Equation (1) to calculate a new power generation output set value. For example, when the reverse power flow prevention margin is calculated for a predetermined period from time t1 to time t2 in Fig. 7, the power generation output setting unit 130 transmits the new power generation output set value to the PCS 20 at time t2 (S245). In the example shown in Fig. 7, a new power generation output set value is set at time t2, and the power generation output reaches the value indicated by the power generation output with a slight delay.

[0047] The power signal receiving unit 100 erases and resets the power receiving point power stored in the storage unit 140 (S250).

[0048] In this way, according to the power generation system of this embodiment, the power generation output is increased or decreased through the reverse power flow prevention margin in response to fluctuations in the power receiving point, making it possible to eliminate wasteful power consumption by the load and the need to set an excessively large reverse power flow prevention margin. As a result, the set value of the power generation output can be increased within a range that prevents reverse power flow. This increases the power transmission to the commercial grid, improving the facility operation rate.

[0049] Second embodiment Next, a power generation system of a second embodiment will be described in detail with reference to Fig. 9. The power generation system of the second embodiment is configured to be able to change the calculation timing (predetermined period) of the power receiving point power average in the power generation system of the first embodiment. The power generation system of the second embodiment has a common configuration with the power generation system of the first embodiment. Fig. 9 is a flowchart showing an example of the operation of the control device 12 in the power generation system 2 of the second embodiment. In the following description, operations common to the first embodiment are denoted by common reference symbols, and duplicated descriptions will be omitted.

[0050] In the power generation system of the first embodiment, the margin setting unit 120 calculates an average value of the power receiving point power at a predetermined timing based on the power receiving point power stored in the storage unit 140. In the power generation system of the second embodiment, this predetermined timing is changeable.

[0051] The margin setting unit 120 calculates an average value of the power receiving point power at a predetermined timing (predetermined period) (Yes in S225) based on the power receiving point power stored in the storage unit 140 (S230). The calculated average value of the power receiving point power (power receiving point power average) is stored in the storage unit 140.

[0052] Next, the margin setting unit 120 calculates the absolute value (power receiving point power deviation) of the difference between the latest (current time) power receiving point from the storage unit 140 and the latest (last stored in the storage unit 140) power receiving point average (S235). The calculated power receiving point power deviation is stored in the storage unit 140 together with information indicating the time.

[0053] Here, the margin setting unit 120 compares the calculated power receiving point power deviation with a predetermined reference value (S236).

[0054] If the power receiving point power deviation is greater than a predetermined reference value, that is, if the fluctuation range of the power receiving point power is greater than the reference value with respect to the power receiving point power average (Yes in S236), the margin setting unit 120 shortens the "predetermined period" for calculating the power receiving point power average (S237). This shortens the calculation period of the power receiving point power average in step S230. The operations after step S237 are the same as those in the first embodiment.

[0055] Fig. 10 is a diagram showing an example of the relationship between the maximum value of the power deviation at the power receiving point and the predetermined time changed by the margin setting unit 120. As shown in Fig. 10, the margin setting unit 120 shortens the predetermined time by a larger shortening amount as the maximum value of the power deviation at the power receiving point increases.

[0056] The relationship between the maximum value of the power receiving point power deviation and the predetermined time changed by the margin setting unit 120 is not limited to the linear characteristic sloping downward to the right shown in Fig. 10. The relationship between the maximum value of the power receiving point power deviation and the predetermined time may be a staircase characteristic sloping downward to the right (step characteristic) or a discrete characteristic sloping downward to the right.

[0057] In this way, according to the power generation system of this embodiment, when the fluctuation range of the power at the receiving point is significantly larger than the average power at the receiving point, the calculation period of the average power at the receiving point is shortened, which makes it possible to more appropriately calculate the average power at the receiving point and reduce the risk of a reverse power flow state.

[0058] Third embodiment Next, a power generation system according to a third embodiment will be described in detail with reference to Fig. 11. Fig. 11 is a block diagram showing the configuration of a control device 13 in a power generation system 3 according to the third embodiment. In the following description, common operating elements to those in the first embodiment are denoted by common reference numerals, and duplicated descriptions will be omitted.

[0059] As shown in Fig. 11, the control device 13 of the power generation system 3 of this embodiment includes a learning calculation unit 150. The learning calculation unit 150 performs learning calculations on the power receiving point power, the power receiving point power average, and the power receiving point power deviation stored in the memory unit 140. As a result of the learning calculations, the learning calculation unit 150 can predict the magnitude of at least one of the power receiving point power average and the power receiving point power deviation caused by the time period or the day of the week. The learning calculation unit 150 may execute an artificial intelligence (AI) learning calculation.

[0060] Like the power generation system 1 of the first embodiment, the power generation system 3 of this embodiment adjusts the reverse power flow prevention margin to prevent the power generation output of the power generation system 3 from becoming excessive. The margin setting unit 123 of this embodiment sets the reverse power flow prevention margin to a small value when the power receiving point power deviation predicted by the learning calculation unit 150 is small. This allows the PCS 20 to increase the power generation output (power generation amount), thereby making it possible to increase the operation rate of the power generation system 3 and improve the equipment efficiency. On the other hand, the margin setting unit 120 sets the reverse power flow prevention margin to a large value when the power receiving point power deviation predicted by the learning calculation unit 150 is large. This allows the PCS 20 to reliably prevent the occurrence of reverse power flow.

[0061] Fig. 12 is an example of the relationship between the power receiving point power deviation predicted by the learning calculation unit 150 and the reverse flow prevention margin. In the example shown in Fig. 12, the reverse flow prevention margin M is obtained using a function fpr(ΔP1) of the predicted power receiving point power deviation ΔP1 instead of the load fluctuation amount of the load 6. In other words, by setting the relationship between the predicted power receiving point power deviation and the reverse flow prevention margin as a linear function fpr(ΔP1) with an increasing tendency, the margin setting unit 120 can obtain the reverse flow prevention margin using this function.

[0062] Fig. 13 is another example of the relationship between the power receiving point power deviation and the reverse power flow prevention margin predicted by the learning calculation unit 150. In the example shown in Fig. 13, the relationship between the predicted power receiving point power deviation ΔP1 and the reverse power flow prevention margin M is expressed as an increasing quadratic function gpr(ΔP1).

[0063] Fig. 14 shows yet another example of the relationship between the power receiving point power deviation predicted by the learning calculation unit 150 and the reverse flow prevention margin. In the example shown in Fig. 14, the relationship between the predicted power receiving point power deviation ΔP1 and the reverse flow prevention margin M is an increasing step-like function hpr(ΔP1). In other words, the reverse flow prevention margin does not have to take continuous values. Similarly, the reverse flow prevention margin may be defined by a discrete function. In this case, digital processing becomes easier.

[0064] In this way, the power generation system 3 of the third embodiment obtains the reverse flow prevention margin using the predicted power receiving point power average and power receiving point power deviation, rather than the power receiving point power average and power receiving point power deviation based on actual measurement data. An appropriate function can be adopted according to the characteristics of the load fluctuation of the load 6, as long as the reverse flow prevention margin also tends to expand (tend to increase) as the predicted power receiving point power average and power receiving point power deviation become larger overall.

[0065] Fig. 15 is a diagram showing the time variation of the power receiving point power etc. in one day. As shown in Fig. 15, the power receiving point power can vary significantly over 24 hours in one day. According to the power generation system 3 of this embodiment, the power receiving point power etc. predicted by the learning calculation unit 150 can be obtained in advance, so that the power generation output setting value can be increased or decreased in advance, thereby increasing the facility operation rate and reliably preventing the occurrence of reverse power flow.

[0066] (Fourth embodiment) Next, a power generation system according to a fourth embodiment will be described in detail with reference to Fig. 16 and Fig. 17. Fig. 16 is a block diagram showing the configuration of a power generation system 4 according to the fourth embodiment. Fig. 17 is a block diagram showing the configuration of a control device 14 in the power generation system 4 according to the fourth embodiment. In the following description, elements common to the first to third embodiments are denoted by common reference numerals, and duplicated description will be omitted.

[0067] As shown in Fig. 16, the power generation system 4 of this embodiment is connected to a weather information source 9 via a network 8 in addition to the elements of the power generation systems 1 to 3 of the first to third embodiments. The network 8 is, for example, a network connected to the public such as the Internet. The weather information source 9 is an information source that provides environmental information including weather conditions, such as a weather information provider.

[0068] 17, the control device 14 of this embodiment has an environmental information receiving unit 160. The environmental information receiving unit 160 receives environmental information from the meteorological information source 9 via the network 8.

[0069] The learning calculation unit 154 learns and calculates the relationship between at least one of the power receiving point power, the power receiving point power average, and the power receiving point power deviation stored in the storage unit 140 and the environmental information. Using the environmental information received by the environmental information receiving unit 160, the learning calculation unit 154 can learn and calculate the relationship between the power receiving point power, the average value of the power receiving point power, and the power receiving point power deviation and the weather information and the like included in the environmental information, and predict it.

[0070] According to the power generation system 4 of this embodiment, the learning calculation unit 154 can realize learning and prediction based on accumulated data as well as environmental factors.

[0071] According to the above first to fourth embodiments, it is possible to increase the power generation output without performing control that consumes surplus power due to an increase in load, and by minimizing the reverse power flow prevention margin provided to the power receiving point.

[0072] Fifth embodiment Next, a power generation system of a fifth embodiment will be described in detail with reference to Fig. 18 and Fig. 19. Fig. 18 is a block diagram showing a configuration of a power generation system 1a of the fifth embodiment. Fig. 19 is a block diagram showing a configuration of a control device 10a in the power generation system 1a of the fifth embodiment. The power generation system of this embodiment further includes a load control unit 170 that controls the auxiliary equipment in addition to the power generation system 1 of the first embodiment. In the following description, elements common to the first embodiment are denoted by common reference numerals, and duplicated description will be omitted.

[0073] The auxiliary machine 7 is, for example, a device necessary for operating the power generation system 1a. Examples of the auxiliary machine 7 include a motor, a pump, and the like for operating the power generation system 1a.

[0074] The load control unit 170 is a functional unit that controls a load that supplies the generated power of the power generation system 1a. When the reverse power flow determination unit 110 determines that the power flow is reverse, the load control unit 170 transmits a control signal to the auxiliary device 7 to increase the load on the auxiliary device 7. In the example shown in FIG. 19, the load control unit 130 controls only the load on the auxiliary device 7, but this is not limited to this. The load control unit 130 may control the load 6 and the load 7, or may control only the load 6.

[0075] According to the power generation system 1a of this embodiment, when a large fluctuation in the load causes a reverse power flow state in the power generation system 1a, the load on the auxiliary device 7 can be increased to prevent surplus power from flowing into the commercial power grid 5.

[0076] According to the power generation system of each of the above-mentioned embodiments, since the received power is controlled with a certain margin for preventing reverse power flow, it is possible to eliminate wasteful power consumption by the load and to eliminate the need to set an excessive margin for preventing reverse power flow. As a result, the set value of the power generation output is increased, the power transmitted to the commercial grid is increased, and the facility operation rate is improved.

[0077] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0078] 1~4, 1a…Power generation system 5…Commercial power system 6. Load 7. Auxiliary equipment 10, 10a, 12, 13, 14...Control device 20...Power conditioner (PCS) 30...Power receiving point power meter 40...fuel cell 50...Grid breaker 100...Power signal receiving unit 110...Reverse power flow determination section 120,123…Margin setting section 130...Power generation output setting unit 140...Storage section 150, 154…Learning calculation unit 160…Environmental Information Receiving Unit 170...Load control unit 180... Circuit breaker control section

Claims

1. A power generation system that supplies power to a load by connecting to a commercial power system, a power generation unit that supplies power to the load based on a predetermined power generation output setting value; A measurement unit that measures a power receiving point power including a power or a current at a power receiving point of the power supplied from the commercial power system to the load; a margin setting unit that calculates a reverse power flow prevention margin of the power generation output of the power generation unit, which suppresses a flow of power or current from the power generation unit to the commercial power grid, based on a power reception point power deviation obtained from a difference between the power reception point power and a power reception point power average that is a time average of the power reception point power; a power generation output setting unit that sets the power generation output set value based on the power receiving point power average and the reverse power flow prevention margin; A power generation system comprising:

2. 2. The power generation system according to claim 1, wherein the margin setting unit changes the reverse flow prevention margin based on a change in the power receiving point power deviation.

3. A storage unit that records the receiving point power average and the receiving point power deviation; A learning calculation unit that learns and predicts at least one of the power receiving point average and the power receiving point deviation, 3. The power generation system according to claim 2, wherein the margin setting unit changes the reverse flow prevention margin based on a result of the prediction calculation.

4. An environmental information receiving unit that receives environmental information including meteorological information via a network, The learning calculation unit learns and performs a prediction calculation on at least one of the power receiving point average or the power receiving point deviation and the relationship with the environmental information. The power generation system according to claim 3 .

5. 5. The power generation system according to claim 3, wherein the learning calculation unit performs AI learning.

6. a reverse power flow determination unit that determines whether or not there is a flow of power or a current from the power generation unit to the commercial power system based on the positive or negative of the power at the power receiving point; an output control unit that stops a power generation output of the power generation system based on a result of the determination by the reverse power flow determination unit; The power generation system of claim 1 further comprising:

7. The load includes an auxiliary device that operates the power generation system, The power generation system comprises: a reverse power flow determination unit that determines whether or not there is a flow of power or a current from the power generation unit to the commercial power system based on the positive or negative of the power at the power receiving point; a load control unit that controls a load of the auxiliary device based on a result of the determination by the reverse power flow determination unit; The power generation system of claim 1 further comprising:

8. A control device that controls a power generation system that is interconnected with a commercial power system and supplies power to a load based on a predetermined power generation output setting value, a power signal receiving unit that receives a signal indicating a power receiving point including power or a current at a power receiving point of the power supplied from the commercial power system to the load; a margin setting unit that calculates a reverse power flow prevention margin of a power output of the power generation system that suppresses a flow of power or current from the power generation system to the commercial power grid based on a power receiving point power deviation obtained from a difference between the power receiving point power and a power receiving point power average that is a time average of the power receiving point power; a power generation output setting unit that sets the power generation output set value based on the power receiving point power average and the reverse power flow prevention margin and transmits the power generation output set value to the power generation system; A control device comprising:

9. 9. The control device according to claim 8, wherein the margin setting unit changes the reverse flow prevention margin based on a change in the power deviation at the receiving point.

10. a reverse power flow determination unit that determines whether or not there is a flow of power or a current from the power generation unit to the commercial power system based on the positive or negative of the power at the power receiving point; an output control unit that stops a power generation output of the power generation system based on a result of the determination by the reverse power flow determination unit; The control device of claim 8 further comprising:

11. The load includes an auxiliary device that operates the power generation system, The control device, a reverse power flow determination unit that determines whether or not there is a flow of power or a current from the power generation unit to the commercial power system based on the positive or negative of the power at the power receiving point; a load control unit that controls a load of the auxiliary device based on a result of the determination by the reverse power flow determination unit; The control device of claim 8 further comprising:

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