Power control device and power control method for a self-consumption type solar power generation system

Abstract

To provide a power control device and a power control method for a self-consumption solar power generation system that covers the power consumption by a load with power generated from solar power generation equipment and power received from a power company.SOLUTION: In a solar power generation system, a power control device includes a data acquisition unit that can acquire a received power value at a cycle of 3 seconds or less, and a control unit that can change the generated power on the basis of the acquired received power value data result. On the basis of the data acquired by the data acquisition unit, the control unit determines whether the formula of (a previous received power value (kW) minus a latest received power value (kW))≥threshold A is satisfied (where the threshold A is preferably greater than 0 and 5 to 30% of the previous received power value (kW)), and if satisfied, the generated power is reduced.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power control device and a power control method for a self-consumption type solar power generation system that uses the generated power from a solar power generation facility and the received power from an electric power company to cover the power consumption by a load. In particular, the present invention relates to a power control device and a power control method for a self-consumption type solar power generation system that can quickly prevent reverse power flow even when the power consumption value rapidly decreases without constantly suppressing the amount of generated power too much.

Background Art

[0002] Conventional solar power generation has been very popular since the implementation of the Feed-in Tariff (FIT) system, which allows electricity to be sold at a fixed and high unit price for 20 years.

[0003] However, due to the decrease in the purchase price of the electric power company, the purchase price for newly installed solar power generation is almost the same as or lower than the electricity price, so the investment interest in solar power generation facilities is gradually disappearing. In addition, an environment has also occurred where the power sales from the facilities generated due to the output control request of the electric power company must be suppressed.

[0004] Under such an environment, the design of solar power generation facilities aiming to self-consume the generated power rather than selling it to the electric power company is increasing. In such a self-consumption type design, it is necessary to control to prevent the reverse power flow of power from the solar power generation system to the electric power company.

[0005] Examples of solar power generation systems that prevent reverse power flow include Patent Documents 1 to 3. Patent Document 1 discloses reducing the amount of power supplied from the solar power generation device to a predetermined value when the difference between the amount of power consumed and the amount of power generated (i.e., the received power value) falls below a set threshold. Patent Document 2 discloses suppressing the amount of power supplied from the solar power generation device when the deficit between the amount of power consumed and the amount of power consumed due to the load falls below a threshold. Furthermore, Patent Document 3 discloses setting an upper limit for the generated power so that the difference between the upper limit of the generated power and the amount of power consumed is a linear function of the power consumed, and controlling the generated power so that it is below this upper limit.

[0006] In all of these solar power generation systems, the amount of electricity generated and consumed is measured at regular time intervals, and the difference between the amount of electricity consumed and the amount of electricity generated at each point in time (i.e., the received power value) is calculated from the obtained data on the amount of electricity generated and consumed. Based on this received power value at each point in time, the amount of electricity generated is controlled.

[0007] When the change in power consumption over time is slow, power control based on the power received at each point in time is sufficient. However, when the change in power consumption over time is rapid, for example, when power consumption drops rapidly in a short time due to the simultaneous shutdown of operations at the start of lunch break in a factory, power control based on the power received at each point in time cannot respond quickly. As a result, even though power consumption has decreased, the generated power remains high, causing the generated power to exceed the power consumption, and resulting in a reverse power flow to the power company.

[0008] To prevent the occurrence of such reverse power flow, it has been common practice to deliberately set the upper limit of the amount of electricity generated significantly lower than the rated power generation capacity of the solar power generation equipment, in other words, to create a large safety margin. In this case, the occurrence of reverse power flow can be prevented, but the large margin means that the amount of electricity generated is constantly suppressed to a low level, which has the problem of not being able to effectively utilize the power generation capacity of the solar power generation system. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2017-93127 [Patent Document 2] Japanese Patent Publication No. 2012-175858 [Patent Document 3] Patent No. 6364567 [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention was devised to solve the problems of the prior art described above, and its purpose is to provide a power control device and power control method for a self-consumption type solar power generation system that can quickly prevent reverse power flow even when power consumption drops sharply, while minimizing the amount of power reduction required to prevent reverse power flow. [Means for solving the problem]

[0011] The inventors of the present invention have conducted diligent studies to achieve the above objectives and have found that by acquiring the latest received power value and the immediately preceding received power value at short intervals of 3 seconds or less, determining whether there is a problem of a sudden drop between the two received power values ​​using a specific formula, and if a problem is found according to that formula, reducing the generated power to prevent reverse power flow, and further, if necessary, even if no problem is found in the above determination, if the latest received power value is lower than a specific value, a tendency for reverse power flow to occur is observed, and the generated power is reduced to prevent reverse power flow, thereby minimizing the margin for suppressing generated power to prevent reverse power flow, it is possible to quickly prevent reverse power flow when it may occur suddenly, and it is also possible to reliably prevent reverse power flow even if there is only a slight tendency for reverse power flow, thus completing the present invention.

[0012] In other words, the present invention has the following configurations [1] to

[17] . [1] A power control device for a self-consumption type solar power generation system that covers the power consumption of a load with power generated from a solar power generation facility and power received from a power company, wherein the power control device includes a data acquisition unit that can acquire the power received value at a period of 3 seconds or less, and a control unit that can change the power generated based on the data result of the acquired power received value, wherein the control unit determines whether the equation (i) (previous power received value (kW) - latest power received value (kW)) ≥ threshold A (where threshold A is greater than 0) is satisfied based on the data acquired by the data acquisition unit, and is configured to reduce the power generated if the equation (i) is satisfied. [2] The power control device according to [1], characterized in that the data acquisition unit is configured to acquire the generated power value at the same interval as the received power value, and when equation (i) is satisfied, the generated power is reduced to the product of the latest generated power value (kW) and a control factor α selected from a value in the range of 0 to 0.90. [3] The power control device according to [1] or [2], characterized in that the threshold A is a value selected from the range of 5 to 30% of the immediately preceding received power value (kW). [4] Power control device according to [2] or [3], characterized in that, if equation (i) is not satisfied, the control unit determines, based on the data acquired by the data acquisition unit, whether the latest received power value (kW) ≥ threshold B (where the threshold B is greater than 0) is satisfied, and if equation (ii) is not satisfied, the power generation device is reduced to the product of the latest generated power value (kW) and a control rate β that is greater than the control rate α but less than 1.0. [5] The power control device according to [4], characterized in that the threshold B is a value selected from a range of 5 to 30% of the rated power generation capacity (kW) of the solar power generation equipment. [6] The power control device according to [4] or [5], characterized in that the control rate β is a value calculated according to the following formula (iii) based on the data acquired by the data acquisition unit. Control rate β = [(Latest generated power value (kW) + Latest received power value (kW)) - Margin amount (kW)] / Rated power generation amount (kW) ... Equation (iii) [7] The power control device according to [6], characterized in that the margin amount is a value selected from the range of 5 to 40% of the latest power generation value (kW). [8] The power control device according to any one of [4] to [7], characterized in that if equation (ii) is satisfied, the determination of whether equation (i) is satisfied is repeated again after the next data acquisition by the data acquisition unit. A self-consumption type solar power generation system characterized by including a power control device described in any of [9][1] to [8].

[10] A method for controlling generated power by a power control device in a self-consumption type solar power generation system that covers the power consumption of a load with power generated from a solar power generation facility and power received from a power company, wherein the power control device includes a data acquisition unit that can acquire a power received value at a period of 3 seconds or less, and a control unit that can change the generated power based on the data result of the acquired power received value, wherein the control unit determines, based on the data acquired by the data acquisition unit, whether the equation (i) (previous power received value (kW) - latest power received value (kW)) ≥ threshold A (where threshold A is greater than 0), and if the equation (i) is satisfied, the generated power is reduced.

[11] The method according to

[10] , characterized in that the data acquisition unit is configured to acquire the generated power value at the same interval as the received power value, and when equation (i) is satisfied, the generated power is reduced to the product of the latest generated power value (kW) and a control factor α selected from a value in the range of 0 to 0.90.

[12] The method according to

[10] or

[11] , characterized in that the threshold A is a value selected from the range of 5 to 30% of the immediately preceding received power value (kW).

[13] If equation (i) is not satisfied, the control unit determines, based on the data acquired by the data acquisition unit, whether the latest received power value (kW) ≥ threshold B (where threshold B is greater than 0) is satisfied, and if equation (ii) is not satisfied, the power control device according to

[11] or

[12] , characterized in that it reduces the power generation to the product of the latest generated power value (kW) and a control rate β that is greater than the control rate α but less than 1.0.

[14] The method according to

[13] , characterized in that the threshold value B is a value selected from the range of 5 to 30% of the rated power generation amount (kW) of the solar power generation facility.

[15] The method according to

[13] or

[14] , characterized in that the control ratio β is a value calculated according to the following formula (iii) based on the data acquired by the data acquisition unit. Control ratio β = [(latest power generation power value (kW) + latest power reception power value (kW)) - margin amount (kW)] / rated power generation amount (kW) … formula (iii)

[16] The method according to

[15] , characterized in that the margin amount is a value selected from the range of 5 to 40% of the latest power generation power value (kW).

[17] When satisfying formula (ii), after the next data acquisition by the data acquisition unit, the determination as to whether formula (i) is satisfied is repeated again, which is the method according to any one of

[13] to

[16] .

Advantages of the Invention

[0013] [[ID=1^4]] According to the present invention, the latest power reception power value and the immediately preceding power reception power value are acquired at a short cycle of 3 seconds or less, and it is determined by a specific formula whether there is a problem of a sharp decrease between the two power reception power values. When it is recognized that there is a problem according to that formula, the power generation power is decreased. Therefore, while minimizing the margin amount of suppressing the power generation power for preventing reverse power flow, it is possible to quickly prevent reverse power flow when reverse power flow may occur suddenly. Further, even if no problem is recognized by the above determination as necessary, when the latest power reception power value is lower than a specific value, the power generation power is also decreased on the assumption that a tendency of reverse power flow is recognized. Therefore, it is possible to surely prevent reverse power flow even when a tendency of reverse power flow is shown even slightly.

Brief Description of the Drawings

[0014] [Figure 1] FIG. 1 is a schematic explanatory diagram of an example of a self-consumption type solar power generation system including the power control device of the present invention.

[0015] [Figure 2]FIG. 2 is an example of a flowchart of a method for controlling generated power when using a conventional power control device.

[0016] [Figure 3] FIG. 3 is an example of a flowchart of a method for controlling generated power when using the power control device of the present invention.

[0017] [Figure 4] FIG. 4 is a graph showing an example of a reverse power flow prevention effect simulation when using a conventional power control device.

[0018] [Figure 5] FIG. 5 is a graph showing another example of a reverse power flow prevention effect simulation when using a conventional power control device.

[0019] [Figure 6] FIG. 6 is a graph showing an example of a reverse power flow prevention effect simulation when using the power control device of the present invention.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the power control device, power control method, and solar power generation system using them of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

[0021] The power control device of the present invention is characterized by using a novel control method capable of quickly preventing reverse power flow due to a rapid decrease in power consumption while minimizing the margin amount of suppression of generated power, and otherwise, a device basically the same as a conventionally known one can be appropriately adopted. Further, the solar power generation system main body controlled using the power control device of the present invention can basically adopt a conventionally known one itself.

[0022] The power control device for a self-consumption type solar power generation system of the present invention covers the power consumption due to the load with power generated from the solar power generation equipment and power received from the power company. The power control device of the present invention includes a data acquisition unit that can acquire the received power value at a short period of 3 seconds or less, and a control unit that can change the power generation power based on the data result of the acquired received power value. The control unit is characterized in that it determines at a short period of time whether there is a risk of a rapid decrease in the received power value using a specific formula (i), and if such a risk is detected, it reduces the power generation power to quickly prevent reverse power flow.

[0023] Figure 1 schematically shows an example of a self-consumption type solar power generation system using the power control device of the present invention. As shown in Figure 1, the solar power generation system 1 of the present invention is a self-consumption type solar power generation system that covers the power consumption of load 4A by power generated from solar power generation equipment 2, power received from power company 3, and optionally power supplied from a storage battery (not shown). The solar power generation system 1 of the present invention is configured to be able to control each of the aforementioned powers using the power control device of the present invention. In the solar power generation system 1 of Figure 1, solar power generation equipment 2 is installed on the roof of a building, and load 4 is shown as requiring a power consumption of 4A, including air conditioning equipment 5 inside the building.

[0024] In the solar power generation system 1, 3A of power is received from the grid of the power company 3 and sent to the distribution board 9. This received power of 3A is measured, for example, by a smart meter 8. The power generated by the solar power generation equipment 2 is output as DC power, converted to AC power by a power conditioner (not shown), and sent to the distribution board 9 as generated power of 2A. The received power of 3A and generated power of 2A collected in the distribution board 9 are sent together to the load 4 and used as a power consumption of 4A.

[0025] The power control device of the present invention includes a data acquisition unit 6 that can acquire measurement data of the power received from the power company 3, i.e., the power received value, and optionally the power generated value, at specific intervals, and a control unit 7 that can change the power generated 2A based on these data results. The data acquisition unit 6 does not need to measure each power itself; it is sufficient if it can acquire measurement data for each power. The data acquired by the data acquisition unit 6 can be sent to a cloud server 11 via the internet 10, for example, and the control unit 7 can also receive data from there. The control unit 7 may be provided integrally with the data acquisition unit 6, or it may be provided separately from the data acquisition unit 6. Furthermore, the control unit 7 may be provided integrally with the power conditioner, or it may be provided separately from the power conditioner.

[0026] Next, the method for controlling generated power in the power control device of the present invention will be described. For ease of understanding, first, an example of a method for controlling generated power using a conventional power control device will be explained with reference to the flowchart in Figure 2, and then, in comparison, an example of a method for controlling generated power using the power control device of the present invention will be explained with reference to the flowchart in Figure 3.

[0027] Figure 2 is an example of a flowchart for controlling generated power using a conventional power control device. As mentioned above, the conventional method of controlling generated power is based on the received power value at each point in time, as shown in Figure 2, and is basically only capable of controlling power based on a temporary decrease in the received power value at each point in time.

[0028] In the flowchart of conventional power generation control shown in Figure 2, when control is started, the data acquisition unit acquires the received power value at a specific period (for example, every 6 seconds). The control unit then determines, based on the received power value at the time of acquisition, whether the received power value has decreased and there is a risk of reverse power flow. Specifically, the need to reduce the generated power is determined by whether the equation Received Power Value ≥ Threshold is satisfied. This threshold is a value of 0 or greater, and the larger the value, the greater the margin for preventing reverse power flow. If the received power value is above this threshold ("Yes" in Figure 2), it is considered that the received power (power consumption) has not decreased, or even if it has decreased, it has not yet reached the dangerous range where reverse power flow may occur, and the generated power is not reduced. On the other hand, if the received power value is less than this threshold ("No" in Figure 2), it is considered that the received power (power consumption) has decreased to the dangerous range where reverse power flow may occur, and the control unit controls the generated power to decrease. This data acquisition, determination, and control of generated power based on it are repeated at a specific period synchronized with the data acquisition.

[0029] In the conventional control method shown in Figure 2, the generated power is controlled based only on the received power value acquired at each point in time. Therefore, it can only perform control based on a temporary decrease in received power (power consumption) at each point in time, and cannot quickly perform control based on a sudden decrease in received power (power consumption) as in the control method of the present invention. Consequently, in the conventional control method shown in Figure 2, the threshold value of the judgment formula described above must be set large in order to reliably prevent reverse power flow, including a sudden decrease in received power (power consumption). As a result, the margin for suppressing generated power is large, and as a result, the capacity of the solar power generation equipment is often suppressed, and its original capacity is not fully utilized.

[0030] Next, an example of a method for controlling generated power when using the power control device of the present invention will be explained with reference to the flowchart in Figure 3. As shown in Figure 3, the method for controlling generated power of the present invention first acquires the received power value at a recent measurement point and the received power value at the measurement point immediately preceding it at short intervals of 3 seconds or less. If the difference between the received power values ​​during these short intervals is greater than or equal to a certain value, it is determined that there is a rapid change in the received power value over time, and the reduction in generated power is controlled to quickly prevent reverse power flow. Furthermore, if necessary, even if a rapid change in the received power value over time is not observed as determined above, if the latest received power value is lower than a certain value, it is determined that there is a tendency for reverse power flow to occur, and the reduction in generated power is controlled in the same way to reliably prevent reverse power flow. In Figure 3, each of the two determination methods described above is shown vertically in time series.

[0031] In the flowchart of the power generation control method of the present invention shown in Figure 3, when control is started, the data acquisition unit acquires the received power value and, optionally, the generated power value at specific intervals of 3 seconds or less (for example, at 2-second intervals). Then, the control unit determines, based on the acquired received power value, whether the generated power has dropped sharply and there is a risk of reverse power flow. The determination is made by calculating the difference between the immediately preceding received power value and the latest received power value and checking whether this difference is greater than or equal to a specific threshold A. Specifically, the necessity of a decrease in generated power is determined by whether the formula (immediately preceding received power value - latest received power value) ≥ threshold A is satisfied. This threshold A is a value greater than 0 and is appropriately determined based on the rate at which the immediately preceding received power value must drop during this short period to avoid the risk of reverse power flow. Preferably, this threshold A is a value selected from the range of 5 to 30% of the immediately preceding received power value (kW).

[0032] If the difference in the received power value is greater than or equal to this threshold A (indicated by "Yes" in the upper rectangle in Figure 3), the received power (power consumption) is considered to have dropped sharply, reaching a dangerous zone where reverse power flow may occur, and the control unit controls the generated power to reduce it. The amount of reduction in generated power in this case is not particularly limited, but it is preferable to control the power to reduce it by 10% or more, and even more so by 20% or more, from the latest generated power value (kW). That is, it is preferable to control the power to reduce it to the product of the latest generated power value (kW) and a control factor α selected from a value in the range of 0 to 0.90 (preferably 0 to 0.80).

[0033] On the other hand, if the difference in the received power value is smaller than this threshold A ("No" in the upper rectangle in Figure 3), it is considered that the received power (power consumption) has not decreased sharply. In this case, if necessary, the process moves to the lower rectangle in Figure 3 to determine whether there has been a decrease in the received power (power consumption) itself. This part is substantially the same as the conventional control of generated power based only on the received power value at each point in time shown in Figure 2 above. The determination here is made by whether the received power value itself at each point in time has fallen below a specific threshold B and there is a risk of reverse power flow. Specifically, the necessity of a decrease in generated power is determined by whether the equation Received power value ≥ Threshold B is satisfied. This threshold B is a value greater than 0, and the larger it is, the larger the margin for preventing reverse power flow. However, since it has already been determined that there has been no sharp decrease in received power, it is not necessary to make it large as in the conventional method in Figure 2. It is preferable that the threshold B is a value selected from the range of 5 to 30% of the rated power generation capacity (kW) of the solar power generation equipment. If the received power value is greater than or equal to this threshold B ("Yes" in the lower rectangle in Figure 3), the received power (power consumption) is considered not to have decreased, or even if it has decreased, it has not yet reached the dangerous zone where reverse power flow may occur, and the generated power is not reduced. On the other hand, if the received power value is less than this threshold B ("No" in the lower rectangle in Figure 3), the received power (power consumption) is considered to have decreased to the dangerous zone where reverse power flow may occur, and the control unit controls the generated power to decrease. Specifically, the control unit controls the generated power to decrease to the product of the latest generated power value (kW) and a control rate β that is greater than control rate α but less than 1.0. Here, the control rate β is a value that can be calculated according to the formula control rate β = [(latest power generation value (kW) + latest power reception value (kW)) - margin amount (kW)] / rated power generation amount (kW) based on the latest power generation value and latest power reception value acquired by the data acquisition unit, and the margin amount is preferably a value of 0 or greater, and in particular a value selected from the range of 5 to 40% of the latest power generation value (kW). This data acquisition, judgment, and control of the two types of power generation based thereon are repeated at a specific period synchronized with the data acquisition.

[0034] In the control method of the present invention shown in Figure 3, the latest received power value and the immediately preceding received power value are first acquired at short intervals, and a rapid decrease in the received power value is determined based on whether the difference between these received power values ​​is above a certain threshold. Therefore, even if there is a risk of reverse power flow occurring due to a rapid decrease in received power (power consumption), it can be quickly prevented. Next, if necessary, the decrease in the received power value itself is also determined based on whether the acquired latest received power value is above a certain threshold, so even if there is a tendency for reverse power flow to occur, it can be reliably prevented. In this way, the control method of the present invention shown in Figure 3 can quickly respond to reverse power flow due to a rapid decrease in received power (power consumption), so there is no need to take a large margin for suppressing generated power for safety as in the conventional method, and therefore the amount of suppression of generated power can be kept to a minimum, and generated power can be used effectively. In addition, since the acquisition period of the received power value is set to be short, the instruction to the power conditioner (PCS) to reduce generated power can be quickly reflected in response to a rapid decrease in the received power value.

[0035] In the control method of the present invention, the acquisition period for the received power value and, optionally, the generated power value in the data acquisition unit is shorter than conventional methods, less than 3 seconds, preferably less than 2.5 seconds, and more preferably less than 2 seconds, in order to quickly detect a rapid decrease in received power (power consumption) and quickly reflect it in the PCS instructions. In the control method of the present invention, the generated power is reduced by determining whether there is a risk of reverse power flow based on whether there is a rapid change in the latest received power value and, optionally, whether there is a decrease in the magnitude of the latest received power value itself. For the former, it is preferable to make the determination using the short acquisition period for the received power value described above, and for the latter, the determination may be made using the same period as the former, but it is sufficient to make the determination using a longer period (i.e., a longer period that is an integer multiple of twice or more the period of the former). [Examples]

[0036] Next, the effects of the control method of the present invention compared to conventional control methods will be specifically shown using the drawings, but the present invention is not limited to the method shown in the drawings.

[0037] Figures 4 and 5 are examples of simulations of the reverse power flow prevention effect of controlling generated power based on the flowchart of the conventional control method shown in Figure 2. Figures 4 and 5 show simulation results under the same conditions (measurement cycle of received power value: 6 seconds), except that the margin amount for constant suppression of generated power is different. In Figure 4, the margin amount is 50 kW, while in Figure 5, the margin amount is set to a larger 100 kW. In the graphs of Figures 4 and 5, the top line shows power consumption, and of the two overlapping lines second from the top, the lighter colored line shows the instruction to the power conditioner (PCS), and the darker colored line shows the generated power that follows that instruction, and the bottom line shows the received power. The received power corresponds to the difference between power consumption and generated power. As can be seen from Figures 4 and 5, in both cases, a sharp decrease in received power (power consumption) occurs at two points during each measurement cycle.

[0038] In the method shown in Figure 4, the margin for constant suppression of generated power is set to a small 50kW. As a result, it is not possible to respond quickly to a sudden drop in received power (power consumption) at either of these two locations, causing generated power to exceed received power (power consumption), resulting in reverse power flow (a phenomenon in the graph of Figure 4 where the received power becomes a negative value). In contrast, in the method shown in Figure 5, the margin for constant suppression of generated power is set to a large 100kW. As a result, the received power does not become a negative value at any location, and reverse power flow is narrowly avoided. In this case, even if there is a sudden drop in received power (power consumption), reverse power flow can be prevented. However, because the margin for constant suppression of generated power is large, the amount of generated power is constantly suppressed to a significantly lower level, and the power generation capacity of the solar power generation system is not being effectively utilized. Furthermore, in both cases, the measurement cycle of received power is long at 6 seconds, so the reflection of the instruction for the decrease in generated power to the PCS is delayed, and it is not possible to respond quickly to the decrease in received power (power consumption).

[0039] On the other hand, Figure 6 is an example of a simulation of the reverse power flow prevention effect of power generation control based on the flowchart of the control method of the present invention shown in Figure 3. In the method of Figure 6, the margin amount for constant suppression of power generation is suppressed to a smaller amount of 15 kW compared to the conventional method shown in Figures 4 and 5. In addition, the measurement period of the received power value is set to a shorter 2 seconds compared to the conventional method shown in Figures 4 and 5. In the graph of Figure 6, the top line shows power consumption, of the two overlapping lines second from the top, the lighter colored one shows the instruction to the PCS, and the darker colored one shows the power generation that follows that instruction, and the bottom line shows the received power. The received power corresponds to the difference between power consumption and power generation.

[0040] In the method shown in Figure 6, first, the received power value at the most recent measurement point and the received power value at the immediately preceding measurement point are obtained. Based on the magnitude of the difference between these received power values, it is determined whether there is a rapid decrease in the received power value and the generated power is controlled accordingly. Then, based on the magnitude of the received power itself at the most recent measurement point, it is determined whether there is a tendency for the received power value to decrease and the generated power is controlled accordingly.

[0041] In the method shown in Figure 6, although the above control is performed, resulting in frequent decreases in generated power, the system can respond quickly to any sudden drop in power consumption. Specifically, during the simulation in Figure 6, generated power is always lower than power consumption, received power is always positive, and no reverse power flow occurs. Furthermore, in the method shown in Figure 6, the margin for constant suppression of generated power for safety is small at 15kW, so constant suppression of generated power is kept to a minimum, and the power generation capacity of the solar power generation system can be effectively utilized. In addition, because the measurement cycle of the received power value is short at 2 seconds, the instruction for a decrease in generated power is quickly reflected in the PCS, allowing for a rapid response to the decrease in received power (power consumption). [Industrial applicability]

[0042] According to the power control device and power control method for a self-consumption type solar power generation system of the present invention, reverse power flow can be quickly prevented even during a sudden drop in power consumption, while minimizing the amount of power reduction required to prevent reverse power flow. Therefore, the present invention is extremely useful to those skilled in the art. [Explanation of symbols]

[0043] 1. Solar power generation system 2. Solar power generation equipment 2A generated power 3. Power companies 3A Received Power 4 load 4A power consumption 5 Air conditioning equipment 6. Measurement data acquisition unit 7 Control Unit 8. Smart Meter 9 Distribution board 10 Internet 11 Cloud Servers

Claims

1. A power control device for a self-consumption type solar power generation system that covers the power consumption of a load with power generated from solar power generation equipment and power received from a power company, wherein the power control device includes a data acquisition unit that can acquire the power received value at a period of 3 seconds or less, and a control unit that can change the power generated based on the data result of the acquired power received value, and the control unit is configured to determine whether the equation (i) (previous power received value (kW) - latest power received value (kW)) ≥ threshold A (where threshold A is greater than 0) is satisfied based on the data acquired by the data acquisition unit, and to reduce the power generated if the equation (i) is satisfied. The data acquisition unit is configured to acquire the generated power value at the same frequency as the received power value, and when equation (i) is satisfied, it is configured to reduce the generated power to the product of the latest generated power value (kW) and the control factor α selected from a value in the range of 0 to 0.

90. The threshold A is a value selected from the range of 5 to 30% of the immediately preceding received power value (kW). If equation (i) is not satisfied, the control unit determines, based on the data acquired by the data acquisition unit, whether equation (ii) is satisfied, where the latest received power value (kW) ≥ threshold B (where threshold B is greater than 0). If equation (ii) is not satisfied, the control unit is configured to reduce the generated power to the product of the latest generated power value (kW) and a control factor β that is greater than the control factor α but less than 1.

0. A power control device characterized in that the threshold B is a value selected from a range of 5 to 30% of the rated power generation capacity (kW) of the solar power generation equipment.

2. The power control device according to claim 1, characterized in that the control rate β is a value calculated according to the following formula (iii) based on the data acquired by the data acquisition unit. Control factor β = [(Latest generated power value (kW) + Latest received power value (kW)) - Margin amount (kW)] / Rated power generation amount (kW) ... Equation (iii)

3. The power control device according to claim 2, characterized in that the margin amount is a value selected from the range of 5 to 40% of the latest generated power value (kW).

4. The power control device according to any one of claims 1 to 3, characterized in that, if equation (ii) is satisfied, the determination of whether equation (i) is satisfied is repeated again after the next data acquisition by the data acquisition unit.

5. A self-consumption type solar power generation system characterized by including the power control device described in claim 1.

6. A method for controlling generated power in a self-consumption type solar power generation system that covers the power consumption of a load with power generated from solar power generation equipment and power received from a power company, wherein the power control device includes a data acquisition unit that can acquire the power received value at a period of 3 seconds or less, and a control unit that can change the generated power based on the data result of the acquired power received value, and the control unit determines, based on the data acquired by the data acquisition unit, whether the equation (i) (previous power received value (kW) - latest power received value (kW)) ≥ threshold A (where threshold A is greater than 0) is satisfied, and if equation (i) is satisfied, the generated power is reduced. The data acquisition unit is configured to acquire the generated power value at the same frequency as the received power value, and if equation (i) is satisfied, the generated power is reduced to the product of the latest generated power value (kW) and the control factor α selected from a value in the range of 0 to 0.

90. The threshold A is a value selected from the range of 5 to 30% of the immediately preceding received power value (kW). If equation (i) is not satisfied, the control unit determines, based on the data acquired by the data acquisition unit, whether equation (ii) is satisfied, where the latest received power value (kW) ≥ threshold B (where threshold B is greater than 0). If equation (ii) is not satisfied, the control unit reduces the generated power to the product of the latest generated power value (kW) and a control factor β that is greater than the control factor α but less than 1.

0. A method characterized in that the threshold B is a value selected from a range of 5 to 30% of the rated power generation capacity (kW) of the solar power generation equipment.

7. The method according to 6, characterized in that the control rate β is a value calculated according to the following formula (iii) based on the data acquired by the data acquisition unit. Control factor β = [(Latest generated power value (kW) + Latest received power value (kW)) - Margin amount (kW)] / Rated power generation amount (kW) ... Equation (iii)

8. The method according to claim 7, characterized in that the margin amount is a value selected from the range of 5 to 40% of the latest power generation value (kW).

9. The method according to any one of 6 to 8, characterized in that if equation (ii) is satisfied, the determination of whether equation (i) is satisfied is repeated after the next data acquisition by the data acquisition unit.

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