Power control device and power control method for self-consumption 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 photovoltaic power generation system that covers the power consumed by a load with power generated by a photovoltaic power generation facility and power received from a power company. In particular, the present invention relates to a power control device and a power control method for a self-consumption type photovoltaic power generation system that can quickly prevent reverse power flow even when the power consumption value suddenly drops without constantly suppressing the amount of generated power to a large extent. [Background technology]

[0002] Conventional solar power generation has been extremely popular since the implementation of the government's feed-in tariff (FIT) system, which allows electricity to be sold at a fixed, high price for 20 years.

[0003] However, due to the decline in the purchase price of electric power companies, the purchase price for new installations is almost the same as the electricity rate or even lower, so the investment attractiveness of solar power generation facilities is disappearing.In addition, an environment has arisen in which electric power companies are forced to curb the sale of electricity generated by their facilities due to requests for output control.

[0004] In this environment, solar power generation facilities are increasingly being designed to generate electricity for self-consumption rather than selling it to electric power companies. In such self-consumption designs, it is necessary to control the system to prevent reverse power flow from the solar power generation system to the electric power company.

[0005] Examples of photovoltaic power generation systems that prevent reverse power flow include Patent Documents 1 to 3. Patent Document 1 discloses that the amount of power supplied from a photovoltaic power generation device is reduced 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, and Patent Document 2 discloses that the amount of power supplied from a photovoltaic power generation device is suppressed when the shortage of the amount of power generated relative to the amount of power consumed by a load falls below a threshold. Patent Document 3 also discloses that the upper limit of the power generation is set so that the difference between the upper limit of the power generation and the power consumption is a linear function of the power consumption, and the power generation is controlled to be below this upper limit.

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

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

[0008] In order to prevent the occurrence of such reverse power flow, it has been common practice to set the upper limit of power generation significantly lower than the rated power generation of the solar power generation facility, i.e., to provide 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 power generation is always kept low, which creates 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 Application Publication No. 2017-93127 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-175858 [Patent Document 3] Patent No. 6364567 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been devised to solve the problems of the prior art described above, and its purpose is to provide 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 power consumption drops suddenly, while minimizing the amount of power generation suppression required to prevent reverse power flow. [Means for solving the problem]

[0011] As a result of extensive research into achieving the above-mentioned object, the inventors have discovered that by acquiring the latest received power value and the immediately preceding received power value at short intervals of 3 seconds or less, using a specific formula to determine whether there is a problem of a sudden drop between the two received power values, and if the formula determines that there is a problem, reducing the generated power to prevent reverse power flow, and if necessary, even if the above determination does not determine that there is a problem, if the latest received power value is lower than a specific value, it is determined that there is a tendency for reverse power flow to occur and similarly reducing the generated power to prevent reverse power flow, thereby minimizing the margin for suppressing generated power to prevent reverse power flow, and that reverse power flow can be quickly prevented when reverse power flow could suddenly occur, and that reverse power flow can be reliably prevented even if there is even the slightest tendency for reverse power flow, thereby completing the present invention.

[0012] That is, 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 consumed by a load with power generated from a solar power generation facility and power received from a power company, the power control device including a data acquisition unit that can acquire received power values ​​at intervals of 3 seconds or less, and a control unit that can change the generated power based on the data results of the acquired received power values, the control unit determining whether or not formula (i) of (last received power value (kW) - latest received power value (kW)) ≧ threshold A (where threshold A is greater than 0) is satisfied based on the data acquired by the data acquisition unit, and configured to reduce the generated power if formula (i) is satisfied. [2] The power control device according to [1], characterized in that the data acquisition unit is configured to be able to acquire the generated power value at the same intervals as the received power value, and when formula (i) is satisfied, the generated power is reduced to the value of the product of the latest generated power value (kW) and a control rate α selected from values ​​in the range of 0 to 0.90. [3] The power control device according to [1] or [2], wherein threshold value A is a value selected from a range of 5 to 30% of the immediately preceding received power value (kW). [4] The power control device according to [2] or [3], characterized in that if formula (i) is not satisfied, the control unit determines whether formula (ii) of the latest received power value (kW) ≧ threshold value B (where threshold value B is greater than 0) is satisfied based on the data acquired by the data acquisition unit, and if formula (ii) is not satisfied, the power control device is configured to reduce the generated power to the value of 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. [5] The power control device according to [4], wherein threshold value B is a value selected from a range of 5 to 30% of the rated power generation amount (kW) of the photovoltaic power generation facility. [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 (kW)] / Rated power generation (kW)...Equation (iii) [7] The power control device according to [6], wherein the margin amount is a value selected from a range of 5 to 40% of the latest generated power value (kW). [8] A power control device according to any one of [4] to [7], characterized in that if formula (ii) is satisfied, the determination of whether formula (i) is satisfied is repeated again after the data acquisition unit acquires the next data. [9] A self-consumption type photovoltaic power generation system comprising the power control device according to any one of [1] to [8].

[10] A method for controlling the generated power by a power control device in a self-consumption solar power generation system that covers the power consumed by a load with power generated from a solar power generation facility and power received from an electric power company, wherein the power control device includes a data acquisition unit that can acquire received power values ​​at intervals of 3 seconds or less, and a control unit that can change the generated power based on the data results of the acquired received power values, and the control unit determines whether or not formula (i) is satisfied, (last received power value (kW) - latest received power value (kW)) ≧ threshold A (where threshold A is greater than 0), based on the data acquired by the data acquisition unit, and reduces the generated power if formula (i) is satisfied.

[11] The method described in

[10] , wherein the data acquisition unit is configured to acquire the generated power value at the same intervals as the received power value, and when formula (i) is satisfied, the generated power is reduced to the value of the product of the latest generated power value (kW) and a control rate α selected from values ​​in the range of 0 to 0.90.

[12] The method according to

[10] or

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

[13] A power control device according to

[11] or

[12] , characterized in that if formula (i) is not satisfied, the control unit determines whether formula (ii) of the latest received power value (kW) ≧ threshold value B (where threshold value B is greater than 0) is satisfied based on the data acquired by the data acquisition unit, and if formula (ii) is not satisfied, the power control device reduces the generated power to the value of 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] , wherein the threshold value B is a value selected from the range of 5 to 30% of the rated power generation capacity (kW) of the solar power generation facility.

[15] The method according to

[13] or

[14] , wherein 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 (kW)] / Rated power generation (kW)...Equation (iii)

[16] The method according to

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

[17] The method according to any one of

[13] to

[16] , characterized in that if formula (ii) is satisfied, after the data acquisition unit acquires the next data, the determination of whether formula (i) is satisfied is repeated again. [Effects of the Invention]

[0013] According to the present invention, the latest received power value and the immediately preceding received power value are acquired at short intervals of 3 seconds or less, a specific formula is used to determine whether there is a problem of a sudden drop between the two received power values, and if the formula determines that there is a problem, the generated power is reduced, thereby making it possible to quickly prevent reverse power flow when it could suddenly occur while minimizing the margin for suppressing generated power to prevent reverse power flow.Furthermore, if necessary, even if the above determination does not determine a problem, if the latest received power value is lower than a specific value, it is determined that there is a tendency for reverse power flow to occur and the generated power is reduced in the same way, making it possible to reliably prevent reverse power flow even if there is even the slightest indication of a tendency for reverse power flow. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic explanatory diagram of an example of a self-consumption type photovoltaic power generation system including a 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 a power control device of the prior art is used.

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

[0017] [Figure 4] FIG. 4 is a graph showing an example of a simulation of the effect of preventing reverse power flow when a power control device of the prior art is used.

[0018] [Figure 5] FIG. 5 is a graph showing another example of a simulation of the effect of preventing reverse power flow when a power control device of the prior art is used.

[0019] [Figure 6] FIG. 6 is a graph showing an example of a simulation of the effect of preventing reverse power flow when the power control device of the present invention is used. DETAILED DESCRIPTION OF THE INVENTION

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

[0021] The power control device of the present invention is characterized by the use of a novel control method that can quickly prevent reverse power flow due to a sudden drop in power consumption while minimizing the margin for suppressing power generation, and other than that, it is possible to appropriately adopt devices that are basically the same as conventionally known devices. Furthermore, the photovoltaic power generation system itself that is controlled using the power control device of the present invention can basically be a conventionally known device.

[0022] The power control device of the self-consumption type photovoltaic power generation system of the present invention covers the power consumption of the load with the power generated by the photovoltaic power generation facility and the power received from the electric 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 cycle of 3 seconds or less, and a control unit that can change the generated power based on the acquired data result of the received power value, and is characterized in that the control unit determines at a short cycle using a specific formula (i) whether there is a risk of a sudden drop in the received power value, and if such a risk is recognized, reduces the generated power to quickly prevent reverse power flow.

[0023] Figure 1 is a schematic diagram illustrating an example of a self-consumption type solar power generation system using a 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 power consumption 4A by a load 4 with power generated 2A from a solar power generation facility 2, power received 3A from a 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 above-mentioned powers using the power control device of the present invention. In the solar power generation system 1 of Figure 1, the solar power generation facility 2 is installed on the roof of a building, and a load 4 including an air conditioning facility 5 inside the building is shown as requiring power consumption 4A.

[0024] In the solar power generation system 1, power 3A is received from the power grid of the electric power company 3 and sent to a distribution board 9. At this time, the received power 3A is measured by, for example, a smart meter 8. Furthermore, the power generated by the solar power generation facility 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 2A. The received power 3A and generated power 2A collected by the distribution board 9 are sent together to a load 4 and used as consumed power 4A.

[0025] The power control device of the present invention includes a data acquisition unit 6 that can acquire measurement data of received power 3A from a power company 3, i.e., the received power value, and, if necessary, the generated power value, at specific intervals, and a control unit 7 that can change the generated power 2A based on the 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 the data from there. The control unit 7 may be provided integrally with the data acquisition unit 6 or separately from the data acquisition unit 6. The control unit 7 may also be provided integrally within a power conditioner or separately from the power conditioner.

[0026] Next, a method for controlling power generation in the power control device of the present invention will be described. For ease of understanding, an example of a method for controlling power generation when a power control device of the prior art is used will first be described with reference to the flowchart in Figure 2, and then, for comparison, an example of a method for controlling power generation when the power control device of the present invention is used will be described with reference to the flowchart in Figure 3.

[0027] Fig. 2 is an example of a flowchart of a method for controlling generated power when a conventional power control device is used. As described above, the conventional method for controlling generated power is based on the received power value at each point in time, as shown in Fig. 2, and basically can only perform control based on a temporary drop in the received power value at each point in time.

[0028] In the flowchart of the conventional power generation control shown in FIG. 2, when control is initiated, the data acquisition unit acquires the received power value at a specific interval (e.g., every six seconds). The control unit then determines whether the received power value has dropped to the point where reverse power flow is likely to occur, based on the received power value at the time of acquisition. Specifically, the need to reduce the generated power is determined based on whether the formula "received power value ≥ threshold" is satisfied. This threshold is a value greater than or equal to zero, and the larger the threshold, the greater the margin for preventing reverse power flow. If the received power value is equal to or greater than this threshold ("Yes" in FIG. 2), it is assumed that the received power (power consumption) has not dropped, or has dropped but has not yet reached a dangerous level 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 FIG. 2), it is assumed that the received power (power consumption) has dropped to a dangerous level where reverse power flow may occur, and the control unit controls the generated power to be reduced. This data acquisition, determination, and control of the generated power based on the data acquisition are repeated at a specific interval that matches the data acquisition.

[0029] The conventional control method shown in Figure 2 controls generated power based only on the received power value acquired at each point in time. Therefore, it can only control based on a temporary drop in received power (power consumption) at each point in time. Unlike the control method of the present invention, it cannot quickly control based on a sudden drop in received power (power consumption). Therefore, the conventional control method shown in Figure 2 must set a large threshold value in the above-mentioned judgment formula to reliably prevent reverse power flow, including a sudden drop 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 facility is often suppressed, and the 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 described with reference to the flowchart of Figure 3. As shown in Figure 3, the method for controlling generated power of the present invention first acquires the received power value at the most recent measurement point and the received power value at the immediately preceding measurement point at short intervals of 3 seconds or less. If the difference between the received power values ​​during these short intervals is equal to or greater than a specific value, it is determined that there is a rapid change in the received power value over time, and the generated power is controlled to be reduced in order to quickly prevent reverse power flow. Furthermore, if necessary, even if no rapid change in the received power value is detected, if the most recent received power value is lower than a specific value, it is determined that there is a tendency for reverse power flow to occur, and the generated power is similarly controlled to be reduced, thereby reliably preventing reverse power flow. In Figure 3, the two determination methods are shown in chronological order, one above the other.

[0031] In the flowchart of the control method for generated power of the present invention shown in FIG. 3, when control is initiated, the data acquisition unit acquires the received power value and, if desired, the generated power value at specific intervals of 3 seconds or less (for example, every 2 seconds). Then, the control unit determines whether the generated power has suddenly decreased and there is a risk of reverse power flow based on the acquired received power value. This determination is made by calculating the difference between the immediately preceding received power value and the latest received power value and determining whether this difference is equal to or greater than a specific threshold A. Specifically, the need for a decrease in generated power is determined based on 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 decrease within this short interval to cause a risk of reverse power flow. This threshold A is preferably a value selected from a range of 5 to 30% of the immediately preceding received power value (kW).

[0032] If the difference in the received power values ​​is equal to or greater than threshold A ("Yes" in the upper rectangle in Figure 3), it is assumed that the received power (power consumption) has dropped sharply and reached a dangerous level where reverse power flow may occur, and the control unit controls the generated power to be reduced. In this case, the amount of reduction in generated power is not particularly limited, but it is preferable to control the generated power to be reduced by 10% or more, or even 20% or more, from the latest generated power value (kW). In other words, it is preferable to control the generated power to be reduced to the value obtained by multiplying the latest generated power value (kW) by a control rate α selected from a range of 0 to 0.90 (preferably 0 to 0.80).

[0033] On the other hand, if the difference in the received power values ​​is smaller than threshold A ("No" in the upper rectangle in Figure 3), it is determined that the received power (power consumption) has not dropped suddenly. In this case, the process proceeds to the lower rectangular section in Figure 3 to further determine, if necessary, whether the received power (power consumption) itself has dropped. This section is essentially the same as the conventional control of generated power based solely on the received power value at each point in time shown in Figure 2. This determination is made based on whether the received power value at each point in time has dropped below a specific threshold B, indicating a risk of reverse power flow. Specifically, the need for a drop in generated power is determined based on whether the formula "received power value ≥ threshold B" is satisfied. This threshold B is a value greater than 0, and the larger the value, the greater the margin for preventing reverse power flow. However, since it has already been determined that there is no sudden drop in received power, it is not necessary to set it large as in the conventional method of Figure 2. Threshold B is preferably a value selected from a range of 5 to 30% of the rated power generation (kW) of the solar power generation facility. If the received power value is equal to or greater than threshold B ("Yes" in the lower rectangle in Figure 3), it is assumed that the received power (power consumption) has not decreased, or has decreased but has not yet reached a dangerous level where reverse power flow may occur, and the generated power is not reduced. On the other hand, if the received power value is smaller than threshold B ("No" in the lower rectangle in Figure 3), it is assumed that the received power (power consumption) has decreased to a dangerous level where reverse power flow may occur, and the control unit controls the generated power to be reduced. Specifically, the control unit controls the generated power to be reduced 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 based on the latest generated power value and latest received power value acquired by the data acquisition unit according to the formula: control rate β = [(latest generated power value (kW) + latest received power value (kW)) - margin amount (kW)] / rated power generation amount (kW), and it is preferable that the margin amount is a value greater than or equal to 0, particularly a value selected from the range of 5 to 40% of the latest generated power value (kW). Such data acquisition, judgment, and two types of generated power control based on that are repeated at a specific cycle that matches the data acquisition.

[0034] The control method of the present invention shown in Figure 3 first acquires the latest received power value and the immediately preceding received power value at short intervals and determines whether a sudden drop in the received power value is greater than or equal to a specific threshold. This allows for rapid prevention of reverse power flow, even if there is a risk of such a drop occurring due to a sudden drop in the received power (power consumption). Second, if necessary, the control method also determines whether the latest acquired received power value is greater than or equal to a specific threshold. This ensures reliable prevention of reverse power flow, even if there is a tendency for reverse power flow to occur. As described above, the control method of the present invention shown in Figure 3 can quickly respond to reverse power flow caused by a sudden drop in the received power (power consumption). Therefore, the control method does not require a large margin for reducing generated power for safety reasons, as in the past. Therefore, the amount of power generation reduction can be minimized, allowing for effective use of generated power. Furthermore, because the received power value acquisition interval is set short, instructions to reduce generated power to the power conditioner (PCS) can be quickly reflected in response to a sudden drop in the received power value.

[0035] In the control method of the present invention, the cycle for acquiring the received power value and, if desired, the generated power value in the data acquisition unit is shorter than conventional cycles, 3 seconds or less, preferably 2.5 seconds or less, and more preferably 2 seconds or less, in order to quickly detect a sudden drop in received power (power consumption) and quickly reflect this in the PCS's instructions. Note that the control method of the present invention determines whether there is a risk of reverse power flow occurring based on whether there is a sudden change in the latest received power value and, optionally, whether there is a decrease in the magnitude of the latest received power value itself, and reduces the generated power accordingly; the former is preferably determined using the short cycle for acquiring the received power value described above, and the latter may be determined using the same cycle as the former, but it is sufficient to determine using a longer cycle (i.e., a cycle that is at least twice as long as the former cycle and an integer multiple of it, for example). [Example]

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

[0037] Figures 4 and 5 are examples of simulations of the effectiveness of preventing reverse power flow by 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 period for received power: 6 seconds) except for the margin for continuous suppression of generated power. The margin is 50 kW in Figure 4, while the margin is a larger 100 kW in Figure 5. In the graphs of Figures 4 and 5, the top line represents power consumption. Of the two overlapping lines from the second highest, the lighter one represents the instruction to the power conditioner (PCS), the darker one represents the generated power according to that instruction, and the bottom line represents the received power. Note that received power is the difference between power consumption and generated power. As can be seen from Figures 4 and 5, in both cases, a sudden drop in received power (power consumption) occurs at two points during each measurement period.

[0038] In the method shown in Figure 4, the margin for continuously suppressing generated power is set to a small 50 kW, which means that the system is unable to respond quickly to the sudden drop in received power (power consumption) at either of these two locations. The generated power exceeds the received power (power consumption), resulting in reverse power flow (the phenomenon in which received power becomes negative in the graph in Figure 4). In contrast, the method shown in Figure 5, which sets a large margin for continuously suppressing generated power to 100 kW, ensures that received power does not become negative at any location, narrowly avoiding reverse power flow. In this case, reverse power flow is prevented even in the event of a sudden drop in received power (power consumption). However, the large margin for continuously suppressing generated power results in the amount of generated power being significantly reduced at all times, resulting in ineffective utilization of the photovoltaic power generation system's power generation capacity. Furthermore, in both cases, the measurement period for received power is long (6 seconds), which means that the PCS is slow to respond to the drop in received power (power consumption), preventing a quick response.

[0039] On the other hand, Figure 6 shows an example of a simulation of the effectiveness of preventing reverse power flow by controlling generated power based on the flowchart of the control method of the present invention in Figure 3. In the method of Figure 6, the margin for continuous suppression of generated power is reduced to 15 kW, which is smaller than that of the conventional methods of Figures 4 and 5. In addition, the measurement period for received power values ​​is set to 2 seconds, which is shorter than that of the conventional methods of Figures 4 and 5. In the graph of Figure 6, the top line represents power consumption, and of the two overlapping lines second from the top, the lighter line represents instructions to the PCS, the darker line represents the generated power following those instructions, and the bottom line represents received power. Note that received power corresponds to the difference between power consumption and generated power.

[0040] In the method of Figure 6, first, the received power value at the most recent measurement point and the received power value at the measurement point immediately before that are obtained, and 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. Next, 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, the above control frequently reduces the generated power, but it is able to respond quickly to any sudden drops in power consumption. That is, during the simulation in Figure 6, the generated power is always lower than the consumed power, the 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 purposes is small at 15 kW, so constant suppression of generated power is kept to a minimum, and the power generation capacity of the solar power generation system is effectively utilized. Furthermore, because the measurement period for received power values ​​is short at 2 seconds, the instruction to reduce generated power is quickly reflected in the PCS, allowing for a quick response to drops in received power (power consumption). [Industrial Applicability]

[0042] The power control device and power control method for a self-consumption type photovoltaic power generation system of the present invention can minimize the amount of power generation suppression required to prevent reverse power flow, and can quickly prevent reverse power flow even when power consumption drops sharply. 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 facilities 2A power generation 3. Electric power companies 3A receiving power 4. Load 4A power consumption 5 Air conditioning equipment 6 Measurement data acquisition section 7 Control Unit 8. Smart Meters 9 Distribution board 10. Internet 11. Cloud Server

Claims

1. A power control device for a self-consumption type solar power generation system that covers power consumption by a load with power generated from a solar power generation facility and power received from an electric power company, the power control device including a data acquisition unit capable of acquiring a received power value at intervals of 3 seconds or less, and a control unit capable of changing the generated power based on the data results of the acquired received power value, the control unit determining whether or not formula (i) of (last received power value (kW) - latest received power value (kW)) ≧ threshold A (wherein threshold A is greater than 0) is satisfied based on the data acquired by the data acquisition unit, and configured to reduce the generated power if formula (i) is satisfied.

2. The power control device according to claim 1, characterized in that the data acquisition unit is configured to be able to acquire the generated power value at the same cycle as the received power value, and when formula (i) is satisfied, the generated power is reduced to the product of the latest generated power value (kW) and a control rate α selected from a range of values ​​from 0 to 0.

90.

3. 3. The power control device according to claim 1, wherein the threshold value A is a value selected from a range of 5 to 30% of the immediately preceding received power value (kW).

4. The power control device according to claim 2, characterized in that, when formula (i) is not satisfied, the control unit determines whether formula (ii) of the latest received power value (kW) ≧ threshold value B (wherein threshold value B is greater than 0) is satisfied based on the data acquired by the data acquisition unit, and, when formula (ii) is not satisfied, reduces the generated power to a value obtained by multiplying the latest generated power value (kW) by a control rate β that is greater than the control rate α but less than 1.

0.

5. 5. The power control device according to claim 4, wherein the threshold value B is a value selected from a range of 5 to 30% of the rated power generation amount (kW) of the photovoltaic power generation facility.

6. 5. The power control device according to claim 4, wherein 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. 7. The power control device according to claim 6, wherein the margin amount is a value selected from a range of 5 to 40% of the latest generated power value (kW).

8. A power control device according to any one of claims 4 to 7, characterized in that, when formula (ii) is satisfied, the determination of whether formula (i) is satisfied is repeated again after the data acquisition unit acquires the next data.

9. A self-consumption type photovoltaic power generation system comprising the power control device according to claim 1.

10. A method for controlling generated power by a power control device in a self-consumption type solar power generation system in which power consumed by a load is covered by power generated from a solar power generation facility and power received from an electric power company, the method being characterized in that the power control device includes a data acquisition unit capable of acquiring a received power value at intervals of 3 seconds or less, and a control unit capable of changing the generated power based on the data results of the acquired received power value, and the control unit determines, based on the data acquired by the data acquisition unit, whether or not formula (i) of (last received power value (kW) - latest received power value (kW)) ≧ threshold A (where threshold A is greater than 0) is satisfied, and if formula (i) is satisfied, the generated power is reduced.

11. The method according to claim 10, characterized in that the data acquisition unit is configured to be able to acquire the generated power value at the same cycle as the received power value, and when formula (i) is satisfied, the generated power is reduced to the product of the latest generated power value (kW) and a control rate α selected from a range of values ​​from 0 to 0.

90.

12. 12. The method according to claim 10, wherein the threshold value A is a value selected from a range of 5 to 30% of the immediately preceding received power value (kW).

13. The power control device according to claim 11, characterized in that, when formula (i) is not satisfied, the control unit determines whether formula (ii) of the latest received power value (kW) ≧ threshold value B (wherein threshold value B is greater than 0) is satisfied based on the data acquired by the data acquisition unit, and when formula (ii) is not satisfied, the power generation power 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.

14. The method according to claim 13, wherein the threshold value B is a value selected from a range of 5 to 30% of the rated power generation capacity (kW) of the photovoltaic power generation facility.

15. The method according to claim 13, 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)

16. 16. The method according to claim 15, wherein the margin amount is a value selected from a range of 5 to 40% of the latest generated power value (kW).

17. The method according to any one of claims 13 to 16, characterized in that, if formula (ii) is satisfied, the determination of whether formula (i) is satisfied is repeated again after the data acquisition unit acquires the next data.

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