Power control device, power control system, and power control method

Abstract

To provide a power control device, a power control system, and a power control method capable of easily controlling an output of a power generation device.SOLUTION: The power control apparatus 10 includes a controller 12 that controls the power generation apparatus 20 and the power storage apparatus 30 connected in parallel to the power grid 80. The controller 12 acquires the maximum input power α of the power storage apparatus 30, the rated output β of the power generation apparatus 20, and the designated power factor φ for reverse power flow to the power grid 80, and when the maximum input power α of the power storage apparatus 30 is greater than the product of the rated output β of the power generation apparatus 20 and the designated power factor φ, the controller 12 sets the set power factor for constant power factor control of the power generation apparatus 20 to a value greater than the designated power factor φ and causes the power generation apparatus 20 to charge the power storage apparatus 30.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a power control device, a power control system, and a power control method. [Background technology]

[0002] BACKGROUND ART Conventionally, a power generation system is known that can transmit information about the presence or absence of reverse power flow from a power measurement unit to a power conditioner (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-179748 Summary of the Invention [Problem to be solved by the invention]

[0004] When controlling the output of a power generation device while transmitting information about the presence or absence of reverse power flow to the power generation device, the control of the power generation device can become complicated. Therefore, it is desired to control the output of the power generation device simply.

[0005] An object of the present disclosure is to provide a power control device, a power control system, and a power control method that can easily control the output of a power generation device. [Means for solving the problem]

[0006] According to an embodiment of the present disclosure, there is provided a power control device that controls a power generation device and a power storage device connected in parallel to a power grid, the control unit acquiring a maximum input power of the power storage device, a rated output of the power generation device, and a designated power factor for reverse power flow to the power grid, and when the maximum input power of the power storage device is greater than the product of the rated output of the power generation device and the designated power factor, sets a set power factor for constant power factor control of the power generation device to a value greater than the designated power factor, and causes the power generation device to charge the power storage device.

[0007] A power control system according to an embodiment of the present disclosure includes the power control device, the power storage device, and the power generation device.

[0008] A power control method according to one embodiment of the present disclosure includes a power control device that controls a power generation device and a power storage device connected in parallel to a power grid, acquiring a maximum input power of the power storage device, a rated output of the power generation device, and a designated power factor for reverse power flow to the power grid, and, when the maximum input power of the power storage device is greater than the product of the rated output of the power generation device and the designated power factor, setting a set power factor for constant power factor control of the power generation device to a value greater than the designated power factor and causing the power generation device to charge the power storage device. [Effects of the Invention]

[0009] According to the power control device, power control system, and power control method of the present disclosure, the output of the power generation device can be easily controlled. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram illustrating an example configuration of a power control system according to the present disclosure. [Figure 2A] 10 is a graph showing an example of the output of a power generating device when the power factor is 0.85. [Figure 2B] 10 is a graph showing an example of the output of a power generating device when the power factor is 0.9. [Figure 3] 1 is a flowchart illustrating an example of a procedure for a power control method according to the present disclosure. [Figure 4] FIG. 10 is a block diagram showing an example of the configuration of a power control system according to another embodiment. [Figure 5] FIG. 2 is a block diagram showing a configuration example in which a power generation device includes a plurality of power generation power conditioners. [Figure 6] FIG. 2 is a block diagram showing a configuration example in which a power storage device includes a plurality of power storage power conditioners. DETAILED DESCRIPTION OF THE INVENTION

[0011] As shown in FIG. 1 , a power control system 1 according to an embodiment of the present disclosure includes a power control device 10, a power generation device 20, a power storage device 30, and a load 40. The power control system 1 does not necessarily include the load 40. The power control system 1 is connected to a power grid 80 to allow reverse power flow, and operates in either a forward power flow state in which power is supplied from the power grid 80, or a reverse power flow state in which power is supplied to the power grid 80. When the power generated by the power generation device 20 is greater than the sum of the power charged to the power storage device 30 and the power consumption of the load 40, the power control system 1 operates in a reverse power flow state in which surplus power is supplied to the power grid 80. The power generation device 20, the power storage device 30, and the load 40 are connected in parallel to the power grid 80 at a node 82. The power supplied to the node 82 from the power grid 80, the power generation device 20, and the power storage device 30 is AC.

[0012] An increase in power supplied to the power grid 80 via reverse power flow can cause the voltage of the power grid 80 to rise. One possible method for suppressing the rise in voltage of the power grid 80 is to supply reactive power to the power grid 80 at a constant rate, i.e., to control the power factor to be less than 1. Therefore, the power company that manages the power grid 80 may request that the power control system 1, which is connected to the power grid 80 to allow reverse power flow, perform constant power factor control at a specified power factor. When connecting the power control system 1 to the power grid 80 to allow reverse power flow, the power company considers various factors and determines the specified power factor so that the voltage of the power grid 80 can be maintained within an appropriate range. The specified power factor is, for example, 0.85, but is not limited to this. In the present disclosure, the specified power factor is represented by φ.

[0013] Although the power generation device 20 can output the generated power at a rated output or less, it is necessary to control the apparent power, which is the sum of active power and reactive power, so that it is equal to or less than the rated output. In this disclosure, the rated output of the power generation device 20 refers to the maximum apparent power that the power generation device 20 can output. Active power is the product of apparent power and power factor. In other words, the upper limit of active power that can be output is the product of rated output and power factor. Therefore, the lower the power factor, the less active power that can be output within a range below the rated output. If the power generated by the power generation device 20 exceeds the output upper limit of active power, the excess power is wasted. However, when there is no reverse power flow, constant power factor control at a specified power factor is not required. Therefore, when there is no reverse power flow, the power control system 1 can increase the output upper limit of active power by setting the power factor to a value higher than the specified power factor.

[0014] In order to make the power factor of the power generation device 20 different between a state where reverse power flow is occurring and a state where reverse power flow is not occurring, the power control system 1 may measure the direction of the current flowing between the power grid 80 and the power generation device 20 to determine whether a reverse power flow is occurring or not. However, measuring the direction of the current to determine a reverse power flow and change the power factor requires complex control. Therefore, it is desired to simply change the power factor of the power generation device 20 to control the output.

[0015] (Configuration example of power control system 1) Hereinafter, as one embodiment of the present disclosure, a configuration example of a power control system 1 that can easily change the power factor of a power generation device 20 to control the output will be described.

[0016] <Electricity storage device 30> The power storage device 30 includes a storage battery 32 and a storage power conversion device 34. The storage battery 32 may include a secondary battery such as a lithium-ion battery. The storage power conversion device 34 may include a storage power conditioner 35. The power conditioner is also called a power conditioning system (PCS). The storage power conditioner 35 is a bidirectional inverter that converts DC power and AC power in both directions.

[0017] The storage power conversion device 34 draws AC power from the node 82 and converts it into DC power to charge the storage battery 32. The storage power conversion device 34 also converts DC power discharged from the storage battery 32 into AC power of a predetermined voltage and frequency and supplies the power to the load 40 through the node 82. The storage power conversion device 34 may also convert DC power discharged from the storage battery 32 into AC power of a predetermined voltage and frequency and supply it as a reverse power flow to the power grid 80 through the node 82. The predetermined voltage and frequency are the voltage and frequency of the AC power supplied from the power grid 80 to the node 82.

[0018] The storage power conversion device 34 can charge the storage battery 32 up to a maximum input power. The maximum input power can be set to the rated capacity of the storage power conditioner 35 when the state of charge (SOC) of the storage battery 32 is sufficiently low. The maximum input power is determined according to the state of charge of the storage battery 32 when the state of charge approaches 100%. Specifically, the value obtained by subtracting the state of charge from 100%, i.e., the smaller the remaining capacity of the storage battery 32, the smaller the maximum input power. The maximum input power of the storage power conversion device 34 is represented by α.

[0019] <Generator 20> The power generation device 20 includes a solar cell 22 and a power generation power conversion device 24. The solar cell 22 may be replaced with a renewable energy power generation device such as a wind power generation device. The solar cell 22 may be replaced with another distributed power source such as a fuel cell. The power generation device 20 may include multiple types of distributed power sources. The power generation power conversion device 24 may include a power generation power conditioner 25. The power generation power conditioner 25 is an inverter that converts DC power output by the solar cell 22 into AC power and outputs it to node 82. When the power generation device 20 includes an AC power source, the power generation power conditioner 25 may be an inverter that converts the voltage or frequency of the AC power output by the AC power source and outputs it to node 82.

[0020] The power generating and power conversion device 24 converts the generated power into AC power of a predetermined voltage and frequency and supplies the power to the load 40 through the node 82. The power generating and power conversion device 24 may also convert the generated power into AC power of a predetermined voltage and frequency and supply it as a reverse power flow to the power grid 80 through the node 82.

[0021] The power generating converter 24 can output power up to a rated output. The rated output of the power generating converter 24 is represented by β. The power generating converter 24 controls the ratio between active power and reactive power according to the set power factor, and controls the output so that the apparent power, which is the sum of active power and reactive power, is equal to or less than the rated output.

[0022] <Power control device 10> The power control device 10 includes a control unit 12 and a communication unit 14. The control unit 12 controls the power generation power conversion device 24 of the power generation device 20 and the power storage power conversion device 34 of the power storage device 30. The control unit 12 may include at least one processor. The processor may include a general-purpose processor such as a CPU (Central Processing Unit) or a dedicated processor such as an FPGA (Field Programmable Gate Array). The processor may execute a program for controlling the power generation power conversion device 24 and the power storage power conversion device 34. The processor may be implemented as a single integrated circuit. An integrated circuit is also referred to as an IC (Integrated Circuit). The processor may be implemented as multiple integrated circuits and discrete circuits connected to each other in a communicative manner. The processor may be implemented based on various other known technologies.

[0023] The power control device 10 may include a memory unit. The memory unit may store various types of information, programs, etc. The memory unit may be configured, for example, with a semiconductor memory. The memory unit may function as a work memory for the control unit 12. The memory unit may be included in the control unit 12.

[0024] 1, the communication unit 14 is communicably connected to the power generation power conversion device 24 and the power storage power conversion device 34. The communication unit 14 may be configured to be able to communicate with the power generation power conversion device 24 and the power storage power conversion device 34 via a wire or wirelessly. The communication unit 14 may be configured to be able to communicate with the power generation power conversion device 24 and the power storage power conversion device 34 using various communication methods.

[0025] <Load 40> When power is not supplied from the power grid 80, the load 40 operates by consuming power supplied from the power generation device 20 or the power storage device 30. When power is supplied from the power grid 80, the load 40 may operate by consuming power supplied from the power grid 80. Even when power is supplied from the power grid 80, the load 40 may operate by consuming power supplied from the power generation device 20 or the power storage device 30. The load 40 is connected in parallel to the node 82. The power supplied to the node 82 is AC. When the load 40 operates on DC, it may be equipped with a converter that converts AC to DC.

[0026] (Example of operation of power control system 1) In the power control system 1, the control unit 12 of the power control device 10 controls the power generation power conversion device 24 and the storage power conversion device 34. When power is reversely flowed from the power control system 1 to the power grid 80, the control unit 12 executes constant power factor control of the power generation power conversion device 24 at a power factor specified by the power company that manages the power grid 80.

[0027] For example, suppose the rated output of the power generating converter 24 is 100 kVA. The rated output is not limited to this example. Also, suppose the specified power factor is 0.85. The specified power factor is not limited to this example. If the rated output of the power generating converter 24 is 100 kVA and the specified power factor is 0.85, the upper limit of the active power output when the power generating converter 24 is controlled to a constant power factor is 85 kW.

[0028] In this case, the relationship between the power generated by solar cell 22 of power generation device 20 and the apparent power, active power, and reactive power output by power generation conversion device 24 is illustrated in the graph of Fig. 2A. In the graph of Fig. 2A, the horizontal axis represents the power generated by solar cell 22. The vertical axis represents the apparent power, active power, and reactive power output by power generation conversion device 24.

[0029] As shown in the graph in Figure 2A, when the power generated by solar cell 22 is 85 kW or less, the generated power is output as active power. However, when the power generated by solar cell 22 reaches 85 kW, the apparent power reaches 100 kVA, i.e., the rated output of power generator 24. Therefore, when the power generated by solar cell 22 exceeds 85 kW, power generator 24 controls the power factor to a constant value of 0.85, so that the apparent power, active power, and reactive power cannot be increased. As a result, the power generated by solar cell 22 that exceeds 85 kW is not output and is wasted.

[0030] On the other hand, when there is no reverse power flow from the power control system 1 to the power grid 80, the control unit 12 can change the setting of the power factor of the power generating power conversion device 24 from the specified power factor. Specifically, the control unit 12 can set the power factor of the power generating power conversion device 24 to a value greater than the specified power factor so as to increase the upper limit of the active power output of the power generating power conversion device 24 and output as much power generated by the solar cell 22 as possible.

[0031] For example, suppose the power factor of the power generating power conversion device 24 is set to 0.9, which is a value greater than the specified power factor. In this case, the relationship between the power generated by the solar cell 22 of the power generating device 20 and the apparent power, active power, and reactive power output by the power generating power conversion device 24 is shown in the graph of Figure 2B. The horizontal and vertical axes of Figure 2B are the same as those of Figure 2A.

[0032] When the power factor is increased from 0.85 to 0.9, the upper limit of the active power output of the power generation and conversion device 24 increases from 85 kW to 90 kW. As a result, as shown in the graph in Fig. 2B, when the power generated by the solar cell 22 is 90 kW or less, the generated power is output as active power as is. In other words, the amount of power generated by the solar cell 22 that is not output and is wasted is reduced.

[0033] The control unit 12 can set the power factor of the power generation power conversion device 24 to a value greater than a specified power factor, provided that the power control system 1 does not generate a reverse power flow to the power grid 80. If the active power output from the power generation power conversion device 24 is less than the sum of the power consumption of the load 40 and the maximum input power of the storage power conversion device 34, the power control system 1 does not generate a reverse power flow to the power grid 80. Even if the power consumption of the load 40 is assumed to be zero, if the active power output from the power generation power conversion device 24 is less than the maximum input power of the storage power conversion device 34, the power control system 1 does not generate a reverse power flow to the power grid 80. Therefore, if the upper limit of the active power output when the power factor is set to a specified power factor is less than the maximum input power of the storage power conversion device 34, the control unit 12 can set the power factor to a value greater than the specified power factor to raise the upper limit of the active power output. The fact that the upper limit of the active power output when the power factor is set to a specified power factor is less than the maximum input power of the storage power conversion device 34 is expressed by the inequality α>β·φ. This inequality α>β·φ is also referred to as the first condition. When the first condition is satisfied, the control unit 12 can set the power factor of the power generating power conversion device 24 to a value greater than the designated power factor.

[0034] When setting the power factor to a value greater than the specified power factor, the control unit 12 may set the power factor based on the magnitude relationship between α and β. Specifically, if the maximum input power of the storage power conversion device 34 is equal to or less than the rated output of the generation power conversion device 24, setting the power factor of the generation power conversion device 24 to a value greater than the specified power factor may result in the active power output of the generation power conversion device 24 being greater than the maximum input power of the storage power conversion device 34. Therefore, the control unit 12 sets the power factor of the generation power conversion device 24 to a value greater than the specified power factor but less than 1 so that the active power output of the generation power conversion device 24 is equal to or less than the maximum input power of the storage power conversion device 34, i.e., so that the power control system 1 does not generate a reverse power flow to the power grid 80. The condition that the maximum input power of the storage power conversion device 34 is equal to or less than the rated output of the generation power conversion device 24 is expressed by the inequality α≦β. This inequality α≦β is also referred to as the second condition. When the first condition and the second condition are both satisfied, the control unit 12 may set the power factor of the power generating power conversion device 24 to a value greater than the specified power factor φ and equal to or less than α / β. In this way, the control unit 12 can calculate and change the power factor of the power generating power conversion device 24 to an appropriate value before actually changing the power factor. As a result, the generated power is used effectively within a range that does not cause reverse power flow.

[0035] On the other hand, when the maximum input power of the storage power conversion device 34 is greater than the rated output of the generator power conversion device 24, even if the power factor of the generator power conversion device 24 is set to 1, the active power output by the generator power conversion device 24 is less than the maximum input power of the storage power conversion device 34. In other words, even if the power factor of the generator power conversion device 24 is set to 1, the power control system 1 does not perform reverse power flow to the power grid 80. Therefore, when the maximum input power of the storage power conversion device 34 is greater than the rated output of the generator power conversion device 24, the control unit 12 can set the power factor of the generator power conversion device 24 to 1. The fact that the maximum input power of the storage power conversion device 34 is greater than the rated output of the generator power conversion device 24 is expressed as the inequality α>β. This inequality α>β is also referred to as the third condition. The third condition corresponds to the negation of the second condition. The control unit 12 may set the power factor of the generator power conversion device 24 to 1 when both the first condition and the third condition are satisfied. In this way, the generated power is effectively utilized within a range where no reverse power flow occurs.

[0036] As described above, the control unit 12 can set the power factor of the power generation power conversion device 24 to a value greater than the specified power factor. Conversely, if the upper limit of the active power output when the power factor is set to the specified power factor is equal to or greater than the maximum input power of the storage power conversion device 34, the control unit 12 sets the power factor to the specified power factor. The fact that the upper limit of the active power output when the power factor is set to the specified power factor is equal to or greater than the maximum input power of the storage power conversion device 34 is expressed as the inequality α≦β·φ. This inequality α≦β·φ is also referred to as the fourth condition. The fourth condition corresponds to the negation of the first condition. When the fourth condition is satisfied, the control unit 12 sets the power factor of the power generation power conversion device 24 to the specified power factor. When the fourth condition is satisfied, i.e., when the first condition is not satisfied, setting the power factor of the power generation power conversion device 24 to the specified power factor avoids changing the power factor more than necessary. As a result, the load on the equipment is reduced.

[0037] The maximum input power of the storage power conversion device 34 is the power that the storage power conversion device 34 can charge into the storage battery 32. Therefore, the maximum input power of the storage power conversion device 34 may change depending on the state of charge of the storage battery 32. For example, when the state of charge of the storage battery 32 approaches 100%, the maximum input power of the storage power conversion device 34 may decrease. If the power factor of the generation power conversion device 24 is set to a value greater than the specified power factor based on the value of the maximum input power before the decrease, the first condition may no longer be satisfied. Therefore, when the maximum input power of the storage power conversion device 34 decreases, the control unit 12 may change the power factor of the generation power conversion device 24 to the specified power factor. This makes it possible to avoid the occurrence of reverse power flow with a simple operation.

[0038] <Example of power control procedure> The control unit 12 of the power control device 10 may execute a power control method that includes, as an example, the steps shown in the flowchart of Fig. 3. The power control method may be realized as a power control program executed by a processor that constitutes the control unit 12. The power control program may be stored in a non-transitory computer-readable medium.

[0039] The control unit 12 acquires the rated output (β) of the power generation power conversion device 24 and the power factor (φ) specified by the power company that manages the power grid 80 (step S1). The control unit 12 may acquire the values ​​of β and φ from the power generation power conversion device 24. The control unit 12 may use values ​​that were input in advance when the power control system 1 was installed as the values ​​of β and φ. The control unit 12 acquires the maximum input power (α) of the storage power conversion device 34 of the power storage device 30 (step S2). The control unit 12 may acquire the value of α from the storage power conversion device 34. The control unit 12 may also calculate the value of α by acquiring the maximum input power of the storage power conditioner 35 and the charging rate of the storage battery 32 from the power storage device 30.

[0040] The control unit 12 determines whether the inequality α>β·φ, i.e., the first condition, is satisfied (step S3). If the first condition is satisfied (step S3: YES), the control unit 12 determines whether the inequality α≦β, i.e., the second condition, is satisfied (step S4). If the second condition is satisfied (step S4: YES), the control unit 12 proceeds to step S6. If the second condition is not satisfied (step S4: NO), i.e., if the third condition is satisfied, the control unit 12 proceeds to step S7.

[0041] If the first condition is not satisfied (step S3: NO), that is, if the fourth condition is satisfied, the control unit 12 sets the power factor of the power generation power conversion device 24 to a specified power factor (φ) (step S5). After executing step S5, the control unit 12 proceeds to the procedure of step S8.

[0042] If the first condition is satisfied and the second condition is satisfied (step S4: YES), the control unit 12 sets the power factor of the power generation conversion device 24 to a value equal to or less than the value (α / β) obtained by dividing the maximum input power of the storage power conversion device 34 by the rated output of the power generation conversion device 24 and greater than the designated power factor (φ) (step S6). After executing step S6, the control unit 12 proceeds to the procedure of step S8.

[0043] If the first condition is satisfied and the second condition is not satisfied (step S4: NO), that is, if the first condition is satisfied and the third condition is satisfied, the control unit 12 sets the power factor of the power generation power conversion device 24 to 1 (step S7). After executing step S7, the control unit 12 proceeds to the procedure of step S8.

[0044] The control unit 12 executes the procedure from steps S1 to S7 to control the output of the power generation device 20, i.e., the output of the power generation device 24, at the power factor set in the power generation power conversion device 24 (step S8). The power factor set in the power generation power conversion device 24 is also referred to as a set power factor. When the set power factor is greater than the specified power factor, the control unit 12 charges the power storage device 30 without allowing reverse power flow from the power generation device 20 to the power grid 80. When the set power factor matches the specified power factor, the control unit 12 may allow reverse power flow from the power generation device 20 to the power grid 80 or may charge the power storage device 30 from the power generation device 20.

[0045] The control unit 12 determines whether the maximum input power (α) of the storage power conversion device 34 has decreased (step S9). If the maximum input power (α) of the storage power conversion device 34 has not decreased (step S9: NO), the control unit 12 returns to the procedure of step S8 and continues to control the output of the power generation device 20 at the set power factor.

[0046] If the maximum input power (α) of the storage power conversion device 34 has decreased (step S9: YES), the control unit 12 determines whether the set power factor is greater than the specified power factor (φ) (step S10). If the set power factor is not greater than the specified power factor (φ) (step S10: NO), that is, if the set power factor is the specified power factor (φ), the control unit 12 returns to the procedure of step S8 and continues to control the output of the power generation device 20 at the set power factor.

[0047] If the set power factor is greater than the specified power factor (φ) (step S10: YES), the control unit 12 changes the set power factor to the specified power factor (φ) (step S11). After executing the procedure of step S11, the control unit 12 returns to the procedure of step S8 and controls the output of the power generation device 20 in a state in which the set power factor has been changed to the specified power factor (φ).

[0048] In the procedure of step S11, the control unit 12 may not immediately change the set power factor to the specified power factor, but may change the set power factor by executing the procedures of steps S3 to S7 for the value after the reduction in the maximum input power of the storage power conversion device 34. The control unit 12 may change the set power factor to a value smaller than the current set power factor and larger than the specified power factor. Alternatively, the control unit 12 may leave the set power factor at 1.

[0049] (summary) As described above, the power control device 10 according to this embodiment determines that no reverse power flow will occur from the power control system 1 to the power grid 80, based on the maximum input power (α) of the storage power conversion device 34, the rated output (β) of the power generation power conversion device 24, and the specified power factor (φ) when reverse power flow occurs to the power grid 80, and can appropriately set the power factor of the power generation power conversion device 24. In this way, it is not necessary to measure whether reverse power flow from the power control system 1 to the power grid 80 is actually occurring. As a result, the power factor of the power generation power conversion device 24 can be appropriately set with a simple configuration.

[0050] (Other embodiments) An example of the configuration of a power control system 1 according to another embodiment will be described below.

[0051] <Setting the power factor according to the power consumption of auxiliary equipment or load 40> As shown in FIG. 4 , the power generation device 20 may further include a transformer 26. The transformer 26 transforms the AC power output from the power generation power conversion device 24 and supplies the resulting power to a node 82. The energy storage power conversion device 34 may further include a transformer 36. The transformer 36 transforms the AC power output from the energy storage power conversion device 34 and supplies the resulting power to a node 82. The energy storage power conversion device 34 may further include a cooling device 37. The cooling device 37 may include equipment such as an air conditioner that cools a cubicle that houses the energy storage power conditioner 35. The cooling device 37 may operate by consuming power supplied from the power grid 80 or power supplied from the power generation device 20. The transformer 36 or the cooling device 37 is also referred to as auxiliary equipment of the energy storage power conversion device 34. The auxiliary equipment may include a sensor that measures the current or voltage of the cubicle wiring.

[0052] In the above-described embodiment, the control unit 12 of the power control device 10 used the maximum input power of the storage-type power conditioner 35 as the maximum input power of the storage-type power conversion device 34. The control unit 12 may also use the sum of the maximum input power of the storage-type power conditioner 35 and the loss of the transformer 36 or the power consumption of the cooling device 37, i.e., the power consumption of the auxiliary equipment, as the maximum input power of the storage-type power conversion device 34. This increases the likelihood that the first condition will be satisfied. As a result, the set power factor is set to a value greater than the designated power factor, and the power generated by the power generation device 20 is used effectively. The control unit 12 may also use the sum of the maximum input power of the storage-type power conditioner 35 and the minimum power consumption of the auxiliary equipment as the maximum input power of the storage-type power conversion device 34. By adding the minimum power consumption of the auxiliary equipment, the risk of reverse power flow occurring when the set power factor is set to a value greater than the designated power factor due to fluctuations in the power consumption of the auxiliary equipment is avoided.

[0053] When the power control system 1 includes a load 40, the control unit 12 may replace the maximum input power (α) of the storage power conversion device 34 used in the first to fourth conditions with the sum of the maximum input power of the storage power conversion device 34 and the power consumption of the load 40. In this case, the control unit 12 may further acquire the power consumption of the load 40 and calculate the sum of the maximum input power of the storage power conversion device 34 and the power consumption of the load 40. By doing so, the first condition is more likely to be satisfied. As a result, the set power factor is set to a value greater than the specified power factor, and the power generated by the power generation device 20 is used effectively.

[0054] Even when the power control system 1 includes a load 40, the control unit 12 may execute the determination of the first to fourth conditions using the maximum input power of the storage power conversion device 34. In this case, the power consumption of the load 40 becomes a margin for avoiding reverse power flow.

[0055] <Controlling reverse power flow based on power selling prices> The communication unit 14 of the power control device 10 may be connected to an EMS 60, which is an external energy management system, via a network 70. The EMS 60 may be realized as an external server or in a cloud environment. The communication unit 14 may acquire the market trading price of electricity in the power grid 80 from the EMS 60. The market trading price includes an hourly electricity selling price or electricity purchasing price. The communication unit 14 may acquire the market trading price by various means other than the EMS 60.

[0056] The control unit 12 can select whether to flow the generated power of the power generation device 20 back to the power grid 80 or to charge the power storage device 30, based on the market transaction price acquired by the communication unit 14. When the power selling price is equal to or lower than the power selling threshold, the control unit 12 may select to charge the power storage device 30 without flowing the generated power back to the power grid 80. In this case, the control unit 12 may set the set power factor to a value greater than the designated power factor and charge the power storage device 30 from the power generation device 20. The power selling threshold may be set to, for example, but is not limited to, 0.01 yen / kWh. The control unit 12 may back flow the power charged in the power storage device 30 to the power grid 80 when the power selling price becomes higher than the power selling threshold. In this way, the generated power is used effectively.

[0057] <Controlling reverse power flow based on demand procurement planning> The wheeling supply planner who operates the power control system 1 submits a demand procurement plan regarding power purchases and sales, i.e., forward flow and reverse flow, to the Organization for Cross-regional Coordination of Transmission Operators in advance. The control unit 12 may select to charge the power storage device 30 without flowing the generated power back into the power grid 80 during a time period in which power sales are set to 0 W in the demand procurement plan, i.e., a time period in which no reverse flow occurs. In this case, the control unit 12 may set the set power factor to a value greater than the specified power factor and charge the power storage device 30 from the power generation device 20.

[0058] <Parallel connection of power conditioners> 5, the power generating power conversion device 24 may include, as the power generating power conditioner 25, a power generating power conditioner 25A and a power generating power conditioner 25B connected in parallel. That is, the power generating power conversion device 24 may include a plurality of power generating power conditioners 25. The power generating device 20 may include, as the solar cell 22, a solar cell 22A connected to the power generating power conditioner 25A and a solar cell 22B connected to the power generating power conditioner 25B. The power generating device 20 may include, as the transformer 26, a transformer 26A connected to the power generating power conditioner 25A and a transformer 26B connected to the power generating power conditioner 25B.

[0059] The control unit 12 may use the total value of the rated outputs of the plurality of power generation inverters 25 as the rated output of the power generation conversion device 24. In the example of Fig. 5, the control unit 12 may use the total value of the rated output of the power generation inverter 25A and the rated output of the power generation inverter 25B as the rated output of the power generation conversion device 24.

[0060] 6, the storage power conversion device 34 may include, as the storage power conditioner 35, a storage power conditioner 35A and a storage power conditioner 35B connected in parallel. That is, the storage power conversion device 34 may include a plurality of storage power conditioners 35. The storage device 30 may include, as the storage battery 32, a storage battery 32A connected to the storage power conditioner 35A and a storage battery 32B connected to the storage power conditioner 35B. The storage device 30 may include, as the transformer 36, a transformer 36A connected to the storage power conditioner 35A and a transformer 36B connected to the storage power conditioner 35B.

[0061] The control unit 12 may use the total value of the maximum input power of each of the multiple power storage power conditioners 35 as the maximum input power of the power storage power conversion device 34. In the example of Fig. 6, the control unit 12 may use the total value of the maximum input power of the power storage power conditioner 35A and the maximum input power of the power storage power conditioner 35B as the maximum input power of the power storage power conversion device 34.

[0062] <AC Parallel Connection of the Power Generation Device 20 and the Power Storage Device 30> As described above, the power generation device 20 and the power storage device 30 are connected in parallel to the power grid 80. The power generation device 20 and the power storage device 30 may be connected in parallel to the power grid 80 via AC. That is, the power generation device 20 and the power storage device 30 may be interconnected to the power grid 80 via AC. The power generation device 20 and the power storage device 30 can be interconnected to the power grid 80 via AC by having functions that comply with, for example, the Grid Interconnection Technical Requirements Guidelines. These guidelines specify the voltage and frequency of AC power. Therefore, devices that have functions that comply with the guidelines can be easily connected in parallel to the power grid 80 via AC, even if they are made by different manufacturers. In this case, for example, it becomes easy to later add a power storage device 30 to a power generation facility that only has a solar power generation device 20.

[0063] Furthermore, even if the power generation device 20 and the power storage device 30 are manufactured by different manufacturers, the control unit 12 of the power control device 10 according to the present disclosure can obtain the rated output and maximum input power from each of the power generation device 20 and the power storage device 30, and easily control the power factor of the power generation device 20.

[0064] On the other hand, when the power generation device 20 and the power storage device 30 are connected via DC, the power generation device 20 and the power storage device 30 need to be operated in cooperation with each other in order to stably operate the power control system 1. In this case, it becomes more difficult to add a power storage device 30 later than in the case of AC connection. For the above reasons, by connecting the power generation device 20 and the power storage device 30 to the power grid 80 via AC, the power generation device 20 and the power storage device 30 can be easily combined.

[0065] The drawings illustrating the embodiments of the present disclosure are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

[0066] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included in the scope of the present disclosure. For example, the functions included in each component can be rearranged so as not to be logically inconsistent, and multiple components can be combined or divided into one.

[0067] In one embodiment, (1) a power control device includes a control unit that controls a power generation device and a power storage device connected in parallel to a power grid. The control unit acquires a maximum input power of the power storage device, a rated output of the power generation device, and a designated power factor for reverse power flow to the power grid, and when the maximum input power of the power storage device is greater than the product of the rated output of the power generation device and the designated power factor, sets a set power factor for constant power factor control of the power generation device to a value greater than the designated power factor, and causes the power generation device to charge the power storage device.

[0068] (2) In the power control device described in (1) above, the power generation device and the power storage device may be connected in parallel to the power grid via AC.

[0069] (3) The power control device described in (2) above may further include a communication unit that acquires a power selling price when a reverse power flow is performed to the power grid. When the power selling price is equal to or lower than a power selling threshold, the control unit may set the set power factor to a value greater than the designated power factor and cause the power generation device to charge the power storage device.

[0070] (4) In the power control device described in any one of (1) to (3) above, when the maximum input power of the power storage device is greater than the product of the rated output of the power generation device and the specified power factor and the maximum input power of the power storage device is equal to or less than the rated output of the power generation device, the control unit may set the set power factor to a value greater than the specified power factor and equal to or less than the value obtained by dividing the maximum input power of the power storage device by the rated output of the power generation device, and charge the power storage device from the power generation device.

[0071] (5) In the power control device described in any one of (1) to (4) above, when the maximum input power of the power storage device is greater than the product of the rated output of the power generation device and the specified power factor, and when the maximum input power of the power storage device is greater than the rated output of the power generation device, the control unit may set the set power factor to 1 and charge the power storage device from the power generation device.

[0072] (6) In the power control device described in any one of (1) to (5) above, the control unit may set the set power factor to the specified power factor when the maximum input power of the storage device is equal to or less than the product of the rated output of the power generation device and the specified power factor.

[0073] (7) In the power control device according to any one of (1) to (6), the power storage device may include a power storage power conditioner and ancillary equipment. The maximum input power of the power storage device may be the sum of the maximum input power of the power storage power conditioner and the power consumption of the ancillary equipment.

[0074] (8) In the power control device according to any one of (1) to (7), the power storage device may include a plurality of power-storage power conditioners connected in parallel, and the maximum input power of the power storage device may be the sum of the maximum input powers of the plurality of power-storage power conditioners.

[0075] (9) In the power control device according to any one of (1) to (8), the power generation device may include a plurality of power generation inverters connected in parallel, and the rated output of the power generation device may be the sum of the rated outputs of the plurality of power generation inverters.

[0076] (10) In the power control device described in any one of (1) to (9) above, the control unit may change the set power factor to the specified power factor when the maximum input power of the storage device decreases while the set power factor is set to a value greater than the specified power factor and the storage device is being charged from the power generation device.

[0077] (11) A power control system according to one embodiment includes the power control device according to any one of (1) to (10) above, the power storage device, and the power generation device.

[0078] (12) A power control method according to one embodiment includes a power control device that controls a power generation device and a power storage device connected in parallel to a power grid, acquiring a maximum input power of the power storage device, a rated output of the power generation device, and a designated power factor for reverse power flow to the power grid; and when the maximum input power of the power storage device is greater than the product of the rated output of the power generation device and the designated power factor, the power control device sets a set power factor for constant power factor control of the power generation device to a value greater than the designated power factor, and charges the power storage device from the power generation device. [Explanation of symbols]

[0079] 1. Power control system 10 Power control device (12: control unit, 14: communication unit) 20 Power generation device (22, 22A, 22B: solar cell, 24: power generation power conversion device, 25, 25A, 25B: power generation power conditioner, 26, 26A, 26B: transformer) 30 Power storage device (32, 32A, 32B: storage battery, 34: power storage power conversion device, 35, 35A, 35B: power storage power conditioner, 36, 36A, 36B: transformer, 37: cooling device) 40 Load 60 EMS 70 Network 80 Power grid (82: nodes)

Claims

1. a control unit that controls a power generation device and a power storage device that are connected in parallel to a power grid, The control unit acquiring a maximum input power of the power storage device, a rated output of the power generation device, and a designated power factor when a reverse power flow is performed to the power grid; When the maximum input power of the power storage device is greater than the product of the rated output of the power generation device and the specified power factor, a set power factor when controlling the power generation device to a constant power factor is set to a value greater than the specified power factor, and the power storage device is charged from the power generation device. Power control device.

2. The power control device according to claim 1 , wherein the power generation device and the power storage device are connected in parallel to the power grid via AC.

3. a communication unit that acquires a power selling price when a reverse power flow occurs to the power grid, the control unit, when the power selling price is equal to or lower than the power selling threshold, sets the set power factor to a value greater than the designated power factor and causes the power generation device to charge the power storage device. The power control device according to claim 2 .

4. 4. The power control device according to claim 1, wherein, when the maximum input power of the power storage device is greater than the product of the rated output of the power generation device and the specified power factor and the maximum input power of the power storage device is equal to or less than the rated output of the power generation device, the control unit sets the set power factor to a value in a range greater than the specified power factor and equal to or less than a value obtained by dividing the maximum input power of the power storage device by the rated output of the power generation device, and charges the power storage device from the power generation device.

5. 4. The power control device according to claim 1, wherein, when a maximum input power of the power storage device is greater than a product of a rated output of the power generation device and the specified power factor and the maximum input power of the power storage device is greater than the rated output of the power generation device, the control unit sets the set power factor to 1 and causes the power storage device to be charged from the power generation device.

6. 4. The power control device according to claim 1, wherein the control unit sets the set power factor to the specified power factor when a maximum input power of the power storage device is equal to or less than a product of a rated output of the power generation device and the specified power factor.

7. The power storage device includes a power storage power conditioner and auxiliary equipment, The maximum input power of the power storage device is the sum of the maximum input power of the power storage power conditioner and the power consumption of the auxiliary equipment. The power control device according to any one of claims 1 to 3.

8. the power storage device includes a plurality of power storage power conditioners connected in parallel, The maximum input power of the power storage device is a total value of the maximum input power of each of the plurality of power storage power conditioners. The power control device according to any one of claims 1 to 3.

9. the power generation device includes a plurality of power generation power conditioners connected in parallel, The rated output of the power generation device is a total value of the rated outputs of the plurality of power generation power conditioners. The power control device according to any one of claims 1 to 3.

10. 4. The power control device according to claim 1, wherein the control unit changes the set power factor to the specified power factor when a maximum input power of the power storage device decreases in a state in which the set power factor is set to a value greater than the specified power factor and the power storage device is being charged from the power generation device.

11. A power control system comprising: the power control device according to claim 1 ; the power storage device; and the power generation device.

12. a power control device that controls a power generation device and a power storage device connected in parallel to a power grid, acquiring a maximum input power of the power storage device, a rated output of the power generation device, and a designated power factor when reverse power flows to the power grid; when the maximum input power of the power storage device is greater than the product of the rated output of the power generation device and the specified power factor, the power control device sets a set power factor when controlling the power generation device to a constant power factor to a value greater than the specified power factor, and causes the power generation device to charge the power storage device; A power control method comprising:

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