Output control device and distributed power supply system

Abstract

To provide an output control device and a distributed power supply system that can suppress the amount of power purchased from a power grid while suppressing the occurrence of a reverse power flow.SOLUTION: The output control device includes a communication unit that accepts inputs of information on the magnitude of power required for a load and information on the magnitude of the current power generation of distributed power supplies and a control unit that controls the operation of power conversion by a power conversion device on the basis of each piece of information. The control unit performs prediction of the power generation amount of the distributed power source after a predetermined time, sets a threshold value for the maximum allowable power to be supplied from the power conversion device to the load, and, on the basis of the predicted power generation amount of the distributed power source after the predetermined time, executes control without output limitation when the maximum power that can be supplied from the power conversion device to the load is below the threshold value, and executes control with output limitation when it is equal to or above the threshold value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to an output control device and a distributed power system.

Background Art

[0002] A fully self-consumption type distributed power system using distributed power sources such as solar power generators, wind power generators, and geothermal power generators is known. The distributed power system includes a power conversion device that converts the generated power of the distributed power source into power corresponding to the load and supplies the converted power to the load, and an output control device that controls the operation of converting the power by the power conversion device.

[0003] In a fully self-consumption type distributed power system, it is desirable to maximize the use of the generated power of the distributed power source and suppress power purchase from the power grid. For this reason, the power conversion device and the output control device perform follow-up control to control the magnitude of the active power supplied from the distributed power source to the load so that the received power (power purchase) from the power grid becomes constant at a set value according to the power consumption at the load. Thereby, it is possible to suppress the occurrence of reverse power flow from the distributed power source to the power grid side and suppress power purchase from the power grid.

[0004] In addition, a fully self-consumption type distributed power system includes a reverse power relay that detects reverse power flow from the power conversion device toward the power grid side. The reverse power relay stops the operation of power conversion of the power conversion device in response to detecting the occurrence of reverse power flow.

[0005] When the operation of power conversion of the power conversion device is stopped in response to the detection of reverse power flow by the reverse power relay, the power purchase power from the power grid side increases, leading to an increase in the electricity bill, and there is a concern that a failure or the like may occur in the load equipment due to rapid fluctuations in power, voltage, and current. Therefore, in the follow-up control, in order to suppress the occurrence of reverse power flow, the set value is set relatively large. However, when the set value is increased, the power purchase power from the power grid side increases.

[0006] Therefore, in a fully self-consumed distributed power system and an output control device used therefor, it is desirable to be able to further suppress the power purchased from the power grid side while suppressing the occurrence of reverse power flow.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] Embodiments of the present invention provide an output control device and a distributed power system that can further suppress the power purchased from the power grid side while suppressing the occurrence of reverse power flow.

Means for Solving the Problems

[0009] According to an embodiment of the present invention, there is provided an output control device used in a fully self-consumption distributed power source system that suppresses power purchase from a power grid to a load by converting power supplied from a distributed power source into AC power corresponding to the load by a power conversion device and supplying the converted AC power to the load. The output control device includes a communication unit that receives inputs of information on the magnitude of power required by the load and information on the magnitude of the current power generation of the distributed power source, and a control unit that controls the operation of power conversion by the power conversion device based on the information on the magnitude of power required by the load and the information on the magnitude of the current power generation of the distributed power source. The control unit predicts the power generation of the distributed power source after a predetermined time based on the information on the magnitude of the current power generation of the distributed power source, and sets a limit threshold for the magnitude of power supplied from the power conversion device to the load based on the information on the magnitude of power required by the load. When the maximum magnitude of power that can be supplied from the power conversion device to the load based on the predicted power generation of the distributed power source after the predetermined time is less than the limit threshold, the control unit performs control without output limitation to control the operation of the power conversion device to output the maximum magnitude of power that can be supplied based on the current power generation of the distributed power source. When the maximum magnitude of power that can be supplied from the power conversion device to the load based on the predicted power generation of the distributed power source after the predetermined time is greater than or equal to the limit threshold, the control unit sets a target value corresponding to the magnitude of power required by the load at the current time, and performs control with output limitation to control the operation of the power conversion device to output power of a magnitude corresponding to the target value, thereby limiting the magnitude of power supplied from the power conversion device to the load to the target value.

Effect of the Invention

[0010] An output control device and a distributed power source system are provided that can further suppress the power purchase power from the power grid side while suppressing the occurrence of reverse power flow.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0012] Hereinafter, each embodiment will be described with reference to the drawings. Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of the sizes between parts, etc. are not necessarily the same as those in reality. Also, even when representing the same part, the dimensions and ratios may be represented differently in the drawings. In the present specification and each figure, the same reference numerals are given to the same elements as those described above with respect to the previously shown figures, and detailed descriptions are omitted as appropriate.

[0013] FIG. 1 is a block diagram schematically showing a solar power generation system according to an embodiment. As shown in FIG. 1, a solar power generation system 10 (distributed power generation system) includes a solar panel 12 (distributed power source), a power conversion device 14, an output control device 16, a monitoring device 18, a switchboard 20, and a power meter 22.

[0014] The photovoltaic power generation system 10 is connected to the power grid 2 and the load 4. The photovoltaic power generation system 10 is a full self-consumption type system that suppresses the purchase of electricity from the power grid 2 to the load 4 by supplying the power generated by the solar panels 12 to the load 4. The power of the power grid 2 is alternating current power. The load 4 is an alternating current load. In other words, the load 4 is a consumer.

[0015] The solar panels 12 generate electricity and supply the generated power. The solar panels 12 generate electricity by utilizing the photovoltaic effect and converting the light energy of sunlight into electrical energy. The generated power of the solar panels 12 is direct current power. The solar panels 12 supply the generated direct current power to the power conversion device 14.

[0016] The power conversion device 14 is connected to the solar panels 12 and is also connected to the load 4 via the transformer 6, the in-plant system 8, etc. The power conversion device 14 converts the power supplied from the solar panels 12 into alternating current power corresponding to the load 4 and supplies the converted alternating current power to the load 4.

[0017] The load 4 is connected to the power conversion device 14 and is also connected to the power grid 2 via the in-plant system 8, the switchboard 20, etc. The load 4 receives the supply of the generated power of the solar panels 12 from the power conversion device 14 and receives the supply of the power that is insufficient with the generated power of the solar panels 12 for the required power from the power grid 2. The power conversion device 14 enables the maximum utilization of the generated power of the solar panels 12, thereby suppressing the purchase of electricity from the power grid 2.

[0018] The output control device 16 controls the operation of power conversion by the power conversion device 14. The monitoring device 18 monitors the operations of the power conversion device 14 and the output control device 16. The monitoring device 18, for example, acquires various information from the power conversion device 14 and the output control device 16 and performs the display of the acquired information, etc., so that the administrator of the photovoltaic power generation system 10 can monitor whether the power conversion device 14 and the output control device 16 are operating normally.

[0019] The switchboard 20 is provided between the power system 2 and the load 4. The switchboard 20 is provided, for example, between the power system 2 and the on-site system 8. The AC power of the power system 2 is supplied to the on-site system 8 and the load 4 via the switchboard 20.

[0020] The wattmeter 22 measures the power supplied to the load 4. In other words, the wattmeter 22 measures the power required by the load 4. The wattmeter 22 is connected to the switchboard 20 via, for example, the communication line 30. The wattmeter 22 measures the power supplied to the load 4 and inputs the measurement result to the switchboard 20 by communicating with the switchboard 20 via the communication line 30.

[0021] The switchboard 20 has, for example, a wattmeter 24 and a reverse power relay 26 (RPR). The wattmeter 24 measures the power supplied from the power system 2 to the load 4. The power supplied from the power system 2 to the load 4 is, in other words, the difference between the power required by the load 4 and the power supplied from the solar panel 12 side to the load 4.

[0022] The switchboard 20 is connected to the output control device 16 via, for example, the communication line 31. The switchboard 20 measures the power measurement results of the wattmeter 22 and the wattmeter 24 and inputs them to the output control device 16 by communicating with the output control device 16 via the communication line 31. Note that the measurement result of the wattmeter 22 may be directly input from the wattmeter 22 to the output control device 16 without passing through the switchboard 20, for example. Also, the power supplied from the power system 2 to the load 4 may be obtained by measuring the voltage value and current value at the connection point and performing calculations on the output control device 16 side based on the measurement results.

[0023] The reverse power relay 26 detects a reverse power flow from the power conversion device 14 toward the power system 2 side. The power conversion device 14 is connected to the power system 2 via a transformer 6, an in-plant system 8, a switchboard 20, and the like. Therefore, when the generated power of the solar panel 12 becomes larger than the power consumed by the load 4, a part of the output power of the power conversion device 14 may flow toward the power system 2 side. The reverse power relay 26 detects the occurrence of such a reverse power flow and performs an operation to suppress the reverse power flow.

[0024] The reverse power relay 26 is connected to the power conversion device 14 via a signal line 35. The reverse power relay 26 inputs a reverse power flow detection signal to the power conversion device 14 in response to the detection of the occurrence of a reverse power flow. For example, the reverse power relay 26 inputs a reverse power flow detection signal to the power conversion device 14 when the state of the reverse power flow continues for a predetermined time or more. In other words, the reverse power relay 26 detects the occurrence of a reverse power flow when the state of the reverse power flow continues for a predetermined time or more, for example. The predetermined time is, for example, about 0.5 seconds or more and 2 seconds or less.

[0025] In response to the input of the reverse power flow detection signal, the power conversion device 14 stops the operation of outputting AC power to the load 4. In this way, the reverse power relay 26 detects a reverse power flow and, in response to the detection of the occurrence of the reverse power flow, stops the operation of the power conversion device 14 that outputs AC power to the load 4. Thereby, the reverse power relay 26 suppresses the continuous flow of the reverse power flow toward the power system 2 side. In other words, the reverse power relay 26 performs the operation of stopping the operation of the power conversion device 14 as an operation to suppress the reverse power flow.

[0026] The reverse power relay 26 may have, for example, a circuit breaker that opens and closes the connection to the power system 2. The reverse power relay 26 may suppress the reverse power flow by stopping the operation of the power conversion device 14 and opening the circuit breaker in response to the detection of the occurrence of the reverse power flow. The operation of suppressing the reverse power flow may be an operation of stopping the operation of the power conversion device 14 and opening the circuit breaker. Note that the reverse power relay 26 does not necessarily have to be provided in the switchboard 20. The reverse power relay 26 may be provided separately from the switchboard 20.

[0027] Further, the reverse power relay 26 detects reverse power flow and also detects signs of reverse power flow. The reverse power relay 26 detects that the power purchased from the power system 2 has fallen below a predetermined value and that the occurrence of reverse power flow is imminent as a sign of reverse power flow. The predetermined value is, for example, 10 kW. However, the predetermined value can be arbitrarily set according to, for example, the magnitude of the power generated by the solar panel 12 and the magnitude of the power consumed by the load 4. Signs of reverse power flow may be referred to as, for example, pre-RPR.

[0028] The reverse power relay 26 is connected to the output control device 16 via the signal line 36. The reverse power relay 26 inputs a detection signal of the sign to the output control device 16 in response to the detection of the sign of reverse power flow.

[0029] The power conversion device 14 includes a conversion circuit 50, a control unit 51, communication units 52 and 53, and an input unit 54.

[0030] The conversion circuit 50 is a circuit that converts the power supplied from the solar panel 12 into AC power corresponding to the load 4. The conversion circuit 50 is, for example, an inverter circuit. The control unit 51 controls the operation of power conversion by the conversion circuit 50.

[0031] The communication unit 52 is connected to the control unit 51 and is also connected to the output control device 16 via the communication line 32. The communication unit 52 communicates with the output control device 16 via the communication line 32. The output control device 16 inputs a control signal for controlling the operation of the power conversion device 14 to the communication unit 52 via the communication line 32. The communication unit 52 receives the input of the control signal from the output control device 16 by communicating with the output control device 16 and inputs the input control signal to the control unit 51. The control unit 51 controls the operation of the conversion circuit 50 based on the control signal input from the communication unit 52. Thereby, the AC power output from the conversion circuit 50 (power conversion device 14) can be controlled according to the control signal input from the output control device 16.

[0032] The communication unit 53 is connected to the control unit 51 and is also connected to the output control device 16 and the monitoring device 18 via the communication line 33. The communication unit 53 communicates with the output control device 16 and the monitoring device 18 via the communication line 33.

[0033] The control unit 51 communicates with the monitoring device 18 via the communication unit 53 and the communication line 33, and transmits to the monitoring device 18 information for monitoring the operation of the power conversion device 14 by the monitoring device 18. The output control device 16 communicates with the monitoring device 18 via the communication line 33, and transmits to the monitoring device 18 information for monitoring the operation of the output control device 16 by the monitoring device 18. In this way, the monitoring device 18 monitors the operations of the power conversion device 14 and the output control device 16 by communicating with the power conversion device 14 and the output control device 16 via the communication line 33. The communication unit 52 is a communication unit used for control, and the communication unit 53 is a communication unit used for monitoring. Note that in the power conversion device 14, control communication and monitoring communication may be performed by one communication unit.

[0034] The input unit 54 is connected to the reverse power relay 26 via the signal line 35. The input unit 54 is also connected to the control unit 51. The input unit 54 inputs to the control unit 51 a detection signal of the occurrence of reverse power flow input from the reverse power relay 26 via the signal line 35. The control unit 51 stops the operation of power conversion by the conversion circuit 50 in response to the input of the detection signal of reverse power flow from the input unit 54.

[0035] In this way, the reverse power relay 26 is connected to the input unit 54 via, for example, the signal line 35, and inputs a detection signal of reverse power flow to the input unit 54 in response to the detection of the occurrence of reverse power flow, thereby stopping the operation of the power conversion device 14. Thereby, as described above, the operation of the power conversion device 14 can be stopped in response to the detection of the occurrence of reverse power flow by the reverse power relay 26, and the reverse power flow to the power system 2 side can be suppressed.

[0036] In communication via communication lines 30 to 33, communication circuits such as communication units 52 and 53 are required. In communication via communication lines 30 to 33, various information can be transmitted and received, such as a control signal representing the magnitude of the output power of the power conversion device 14. On the other hand, in communication via communication lines 30 to 33, a communication delay occurs due to the processing of communication units 52, 53, etc. Communication via communication lines 30 to 33 is communication compliant with a communication standard such as Ethernet or RS485, for example. In other words, communication units 52 and 53 are communication circuits compliant with a predetermined communication standard.

[0037] In communication via signal line 35, only binary state inputs can be made, such as the input of a reverse power flow detection signal and the stop of the input, for example. The detection signal is a signal having two states, for example, a reverse power flow detection state and a non-detection state. On the other hand, in communication via signal line 35, communication delay due to processing of the communication unit, etc. is suppressed, and inputs of each signal can be made at a higher speed compared to communication via communication lines 30 to 33. Communication via signal line 35 is communication by switching the on / off of contacts such as a relay, for example. Input unit 54 is a circuit that uses contact inputs faster than communication by communication units 52 and 53. Input unit 54 is, for example, an input / output terminal (IO terminal). Signal line 35 is, for example, a hard wire.

[0038] In the photovoltaic power generation system 10, the power output from the power conversion device 14 (conversion circuit 50) is controlled by communication using communication lines 30 to 33. On the other hand, communication using signal line 35 is used for stopping the operation of the power conversion device 14 in conjunction with the detection of reverse power flow by the reverse power relay 26. Thereby, the stop of the operation of the power conversion device 14 in conjunction with the detection of reverse power flow can be performed at a higher speed than communication using communication lines 30 to 33. Thus, the photovoltaic power generation system 10 uses contact inputs faster than communication using communication lines 30 to 33 for executing the stop of the operation of the power conversion device 14 in conjunction with the detection of reverse power flow.

[0039] The output control device 16 includes a control unit 60, communication units 61 to 63, and an input unit 64. The communication unit 61 is connected to the control unit 60 and is also connected to the power receiving board 20 via the communication line 31. By communicating with the power receiving board 20 via the communication line 31, the communication unit 61 receives the input of the measurement results of the wattmeter 22 and the measurement results of the wattmeter 24 from the power receiving board 20, and inputs the received measurement results of the wattmeter 22 and the measurement results of the wattmeter 24 to the control unit 60. In other words, by communicating with the power receiving board 20, the communication unit 61 receives the input of information on the magnitude of the power required by the load 4 and information on the magnitude of the purchased power supplied from the power grid 2 to the load 4, and inputs the received information on the magnitude of the power required by the load 4 and information on the magnitude of the purchased power supplied from the power grid 2 to the load 4 to the control unit 60.

[0040] Note that the information on the magnitude of the power required by the load 4 and the information on the magnitude of the purchased power supplied from the power grid 2 to the load 4 are not limited to being obtained from the power receiving board 20, and may be obtained from another device such as the monitoring device 18, for example. The configuration for obtaining the information on the magnitude of the power required by the load 4 and the information on the magnitude of the purchased power supplied from the power grid 2 to the load 4 is not limited to the above, and any configuration that can appropriately obtain each piece of information by communication by the communication unit 61 may be used.

[0041] The communication unit 62 is connected to the control unit 60 and is also connected to the communication unit 52 of the power conversion device 14 via the communication line 32. The communication unit 62 receives the input of a control signal for controlling the operation of the power conversion device 14 from the control unit 60. By communicating with the communication unit 52 of the power conversion device 14 via the communication line 32, the communication unit 62 inputs the control signal input from the control unit 60 to the communication unit 52 via the communication line 32. In other words, the communication unit 60 transmits a control signal to the communication unit 52.

[0042] Further, the communication unit 62 communicates with the communication unit 52 of the power conversion device 14 via the communication line 32, receives the input of information regarding the state monitoring of the power conversion device 14 from the power conversion device 14, and inputs the input information regarding the state monitoring to the control unit 60. The information regarding the state monitoring includes information on the magnitude of the current power generation of the solar panel 12. In other words, the communication unit 62 receives the input of information on the magnitude of the current power generation of the solar panel 12 by communicating with the communication unit 52, and inputs the input information on the magnitude of the current power generation of the solar panel 12 to the control unit 60. The magnitude of the current power generation of the solar panel 12 is, in other words, the magnitude of the power that can be supplied from the power conversion device 14 to the load 4 at the current time. The current time is, for example, the time when the communication unit 52 and the communication unit 62 communicate (the time when the output control device 16 receives the input of information on the magnitude of the power generation).

[0043] Note that the information on the magnitude of the current power generation of the solar panel 12 is not limited to being obtained from the power conversion device 14, and may be obtained from another device such as the monitoring device 18, for example. The configuration for obtaining the information on the magnitude of the current power generation of the solar panel 12 is not limited to the above, and may be any configuration that can appropriately obtain the information by communication by the communication unit 62.

[0044] The communication unit 63 is connected to the control unit 60 and is also connected to the monitoring device 18 via the communication line 33. The communication unit 63 communicates with the monitoring device 18 via the communication line 33 and transmits information for monitoring the operation of the output control device 16 to the monitoring device 18.

[0045] In the output control device 16, the communications of the respective communication units 61 to 63 may be performed by one communication unit. The number of communication units provided in the output control device 16 may also be one. The output control device 16 may receive the input of information on the magnitude of the power required by the load 4, information on the magnitude of the purchased power supplied from the power system 2 to the load 4, and information on the magnitude of the current power generation of the solar panel 12, by one communication unit. The configuration for receiving the input of information on the magnitude of the power required by the load 4, information on the magnitude of the purchased power supplied from the power system 2 to the load 4, and information on the magnitude of the current power generation of the solar panel 12 may be any configuration that can appropriately receive the input of each piece of information by at least one communication unit.

[0046] The input unit 64 is connected to the control unit 60 and is also connected to the reverse power relay 26 via the signal line 36. The input unit 64 inputs a reverse power flow prediction detection signal input from the reverse power relay 26 via the signal line 36 to the control unit 60.

[0047] The control unit 60 controls the operation of power conversion by the power conversion device 14 based on each piece of information on the magnitude of the power required by the input load 4, information on the magnitude of the purchased power supplied from the power system 2 to the load 4, and information on the magnitude of the current power generation of the solar panel 12.

[0048] The control unit 60 predicts the power generation of the solar panel 12 after a predetermined time based on the input information on the magnitude of the current power generation of the solar panel 12. The control unit 60, for example, acquires each piece of information at each predetermined control cycle, and controls the operation of the power conversion device 14 based on the acquired each piece of information. The control unit 60, for example, predicts the power generation of the solar panel 12 in the next control cycle.

[0049] For example, based on the information about the current power generation of the solar panel 12 that has been input, the control unit 60 predicts the power generation of the solar panel 12 after a predetermined time through trend monitoring. For example, the control unit 60 obtains the slope of the magnitude of the power generation based on the magnitude of the power generation in the previous control cycle and the magnitude of the power generation in the current control cycle, and predicts the power generation of the solar panel 12 after a predetermined time (control cycle) based on the predetermined time and the slope. For example, the control unit 60 predicts the power generation of the solar panel 12 after a predetermined time as the magnitude of the power obtained by extending the magnitude of the current power generation based on the obtained slope until the predetermined time.

[0050] For example, the control unit 60 may further obtain information regarding the predicted amount of power generation of the solar panel 12. When the distributed power source is the solar panel 12, the information regarding the predicted amount of power generation is, for example, the information on the solar radiation amount at the location where the solar panel 12 is installed. For example, the control unit 60 calculates the predicted amount of power generation of the solar panel 12 based on the obtained information regarding the predicted amount of power generation. The information regarding the predicted amount of power generation may be, for example, information representing the predicted amount of power generation of the solar panel 12 calculated externally based on information such as the solar radiation amount. The information regarding the predicted amount of power generation is not limited to the above, and may be any information that enables the control unit 60 to appropriately recognize the predicted amount of power generation.

[0051] For example, based on the information about the current power generation of the solar panel 12 and the information regarding the predicted amount of power generation of the solar panel 12, the control unit 60 predicts the power generation of the solar panel 12 after a predetermined time. For example, the control unit 60 predicts the power generation of the solar panel 12 after a predetermined time by correcting the power generation of the solar panel 12 predicted by the above trend monitoring according to the predicted amount of power generation calculated based on factors such as the solar radiation amount. Thereby, the power generation of the solar panel 12 after a predetermined time can be predicted with higher accuracy.

[0052] Information regarding the predicted power generation of the solar panel 12 is obtained from an external device such as the monitoring device 18, for example, through communication by the communication unit 63. In other words, the communication unit 63 receives the input of information regarding the predicted power generation of the solar panel 12 from an external device. The external device may be, for example, an external server that provides weather information. The external device may be any device that can appropriately obtain information regarding the predicted power generation of the solar panel 12.

[0053] The control unit 60 may, for example, obtain information regarding the predicted power generation at the time of the next control cycle at any time for each control cycle, or may obtain information regarding the predicted power generation for one day in a lump sum, such as on the previous day or early in the morning. The configuration for obtaining information regarding the predicted power generation may be any configuration that can appropriately obtain information regarding the predicted power generation.

[0054] The control unit 60 does not necessarily have to obtain information regarding the predicted power generation of the solar panel 12. The method for predicting the power generation of the solar panel 12 after a predetermined time by the control unit 60 is not limited to the above, and may be any method that can be appropriately predicted based on at least the information on the magnitude of the current power generation of the solar panel 12.

[0055] The control unit 60 sets a limit threshold for the magnitude of the power supplied from the power conversion device 14 to the load 4 based on the information on the magnitude of the power required by the load 4. The control unit 60 sets the limit threshold by subtracting a predetermined value from the magnitude of the power required by the load 4 at the current time. The predetermined value is, for example, 1 kW. In this way, the limit threshold is set to a value larger than the magnitude of the power at which a reverse power flow omen is detected by, for example, the reverse power relay 26. However, the predetermined value can be arbitrarily set according to the magnitude of the power generated by the solar panel 12, the magnitude of the power consumed by the load 4, etc. The limit threshold does not necessarily have to be a value larger than the magnitude of the power at which a reverse power flow omen is detected by the reverse power relay 26.

[0056] The control unit 60 determines whether the magnitude of the maximum power that can be supplied from the power conversion device 14 to the load 4 based on the predicted power generation power of the solar panel 12 after a predetermined time is equal to or greater than the limit threshold value. In other words, the control unit 60 determines whether the output power of the power conversion device 14 becomes equal to or greater than the limit threshold value after a predetermined time when the maximum power that can be supplied based on the power generation power of the solar panel 12 is output to the power conversion device 14.

[0057] When the magnitude of the maximum power that can be supplied from the power conversion device 14 to the load 4 based on the predicted power generation power of the solar panel 12 after a predetermined time is less than the limit threshold value, the control unit 60 performs control without output limitation to control the operation of the power conversion device 14 so as to output the maximum power that can be supplied based on the current power generation power of the solar panel 12.

[0058] The control unit 60 is connected to the input unit 54 of the power conversion device 14 via the signal line 37. In the control without output limitation, the control unit 60 inputs a control signal indicating the execution of the control without output limitation to the input unit 54 of the power conversion device 14 via the signal line 37. The control unit 60 instructs the power conversion device 14 to execute the control without output limitation, for example, by switching the contact signal from the off state to the on state.

[0059] When the control unit 51 of the power conversion device 14 receives the input of a control signal indicating the execution of the control without output limitation, it controls the operation of the conversion circuit 50 so as to output the maximum power that can be supplied based on the current power generation power of the solar panel 12.

[0060] Accordingly, when the magnitude of the maximum power that can be supplied from the power conversion device 14 to the load 4 based on the predicted power generation power of the solar panel 12 after a predetermined time is less than the limit threshold, the power of the maximum magnitude that can be supplied based on the current power generation power of the solar panel 12 can be supplied from the power conversion device 14 to the load 4. In other words, when the magnitude of the maximum power that can be supplied from the power conversion device 14 to the load 4 based on the predicted power generation power of the solar panel 12 after a predetermined time is less than the limit threshold, the operation of the power conversion device 14 can be controlled so that power generation can be performed up to the limit that does not exceed the power required by the load 4.

[0061] Note that the control signal indicating the execution of control without output limitation may be input to the communication unit 52 of the power conversion device 14 via the communication line 32, not limited to the signal line 37. The method of inputting the control signal indicating the execution of control without output limitation to the power conversion device 14 is not limited to the above, and any method that can appropriately input the control signal indicating the execution of control without output limitation to the power conversion device 14 may be used. In the configuration of inputting to the input unit 54 via the signal line 37, for example, delays in the input of the control signal indicating the execution of control without output limitation can be suppressed. For example, compared with a configuration of inputting via a communication unit, etc., the communication configuration can be made simpler, and the device configurations of the power conversion device 14 and the output control device 16 can also be made simpler.

[0062] On the other hand, when the magnitude of the maximum power that can be supplied from the power conversion device 14 to the load 4 based on the predicted power generation power of the solar panel 12 after a predetermined time is equal to or greater than the limit threshold, the control unit 60 sets a target value according to the magnitude of the power required by the load 4 at the current time, and controls the operation of the power conversion device 14 so as to output power of a magnitude corresponding to the target value, thereby performing control with output limitation that limits the magnitude of the power supplied from the power conversion device 14 to the load 4 to the target value.

[0063] In the control with output limitation, the control unit 60 sets the target value by subtracting the set value from the magnitude of the power required by the load 4 at the current time. In the control with output limitation, the control unit 60 inputs a control signal representing the set target value to the communication unit 52 of the power conversion device 14 via the communication line 32.

[0064] When the control unit 51 of the power conversion device 14 receives the input of the control signal representing the target value, it controls the operation of the conversion circuit 50 so as to output power of a magnitude corresponding to the target value. Thereby, when the magnitude of the maximum power that can be supplied from the power conversion device 14 to the load 4 based on the predicted power generation power of the solar panel 12 after a predetermined time is equal to or greater than the limit threshold value, power of a magnitude corresponding to the target value can be supplied from the power conversion device 14 to the load 4. The magnitude of the power supplied from the power conversion device 14 to the load 4 can be limited to the target value, suppressing the increase in the power purchased from the grid while suppressing the occurrence of reverse power flow.

[0065] For example, when setting the target value, the control unit 60 determines whether the trend of the change in the power required by the load 4 is an upward trend or a downward trend, and changes the set value according to whether it is an upward trend or a downward trend. For example, the control unit 60 obtains the difference between the magnitude of the power required by the load 4 in the previous control cycle and the magnitude of the power required by the load 4 in the current control cycle, and when the magnitude of the power required by the load 4 in the current control cycle is larger (when it is 0 or more), it determines that it is an upward trend, and when the magnitude of the power required by the load 4 in the current control cycle is smaller (when it is less than 0), it determines that it is a downward trend.

[0066] The control unit 60 uses, for example, the first set value in an upward trend and uses a second set value larger than the first set value in a downward trend. As a result, when the load power is increasing with a low possibility of reverse power flow, the difference between the magnitude of the power required by the load 4 and the magnitude of the power supplied from the power conversion device 14 to the load 4 can be reduced, and the power purchased from the power grid 2 can be more suppressed. Then, when the load power is decreasing with a possibility of reverse power flow, the difference between the magnitude of the power required by the load 4 and the magnitude of the power supplied from the power conversion device 14 to the load 4 is made larger than in the upward trend, and the occurrence of reverse power flow can be more appropriately suppressed.

[0067] The first set value is set, for example, to a value larger than the target value than the magnitude of the power at which a sign of reverse power flow is detected by the reverse power relay 26. The first set value is set, for example, to the same value as a predetermined value used for setting the limit threshold. As a result, in the upward trend, the power generated by the solar panel 12 can be utilized up to the limit that does not exceed the power required by the load 4.

[0068] Also, the control unit 60 changes the control cycle depending on whether it is an upward trend or a downward trend, for example. The control unit 60 makes the control cycle in the upward trend shorter than the control cycle in the downward trend, for example. As a result, even when the first set value is made smaller than the second set value, the occurrence of reverse power flow can be suppressed.

[0069] The control period during the downward trend is set to the same value as the control period when the magnitude of the maximum power that can be supplied from the power conversion device 14 to the load 4 based on the generated power of the solar panel 12 after a predicted predetermined time is less than the limit threshold. In other words, the control unit 60 shortens the control period only when the load power is on an upward trend and is equal to or greater than the limit threshold. However, the control period during the downward trend may be different from the control period when it is less than the limit threshold. When it is less than the limit threshold, the possibility of reverse power flow is low. Therefore, the control period when it is less than the limit threshold may be, for example, longer than the control period during the downward trend. Thereby, for example, the operating load of the control unit 60 can be reduced. For example, compared with the case where the control unit 60 continues to operate in a state with a short control period, an increase in power consumption and an increase in the failure frequency in the control unit 60 can be suppressed.

[0070] Further, the control unit 60 detects a disturbance (sudden change) in the generated power of the solar panel 12. The control unit 60 detects, for example, a change in the slope of the magnitude of the generated power that is equal to or greater than a predetermined value as a disturbance in the generated power. When an upward or downward disturbance occurs in the generated power of the solar panel 12, high-speed control is required to suppress the occurrence of reverse power flow and an increase in the power purchased. Therefore, when the control unit 60 detects a disturbance in the generated power, it shortens the control period. For example, when the control unit 60 detects a disturbance in the generated power, it shortens the control period even more than when the load power is on an upward trend and is equal to or greater than the limit threshold. Thereby, even when a disturbance occurs in the generated power, the occurrence of reverse power flow and an increase in the power purchased can be more appropriately suppressed.

[0071] FIG. 2 is a flowchart schematically showing an example of the operation of the solar power generation system according to the embodiment. As shown in FIG. 2, in the solar power generation system 10, the reverse power relay 26 detects a reverse power flow from the power conversion device 14 toward the power grid 2 side (step S101 in FIG. 2). The reverse power relay 26 inputs a reverse power flow detection signal to the power conversion device 14 and the output control device 16 in response to the detection of the occurrence of reverse power flow.

[0072] The power conversion device 14 and the output control device 16 stop the operation of outputting AC power to the load 4 in response to the input of a reverse power flow detection signal (step S102 in FIG. 2). Thereby, it is possible to suppress the continuous flow of reverse power flow to the power grid 2 side.

[0073] In a state where the occurrence of reverse power flow is not detected by the reverse power relay 26, the control unit 60 of the output control device 16 acquires information on the magnitude of the power required by the load 4 (load power information), information on the magnitude of the purchased power supplied from the power grid 2 to the load 4 (purchased power information), and information on the magnitude of the current power generation of the solar panel 12 (power generation power information) every predetermined control cycle (step S103 in FIG. 2).

[0074] The control unit 60 acquires information on the magnitude of the power required by the load 4 and information on the magnitude of the purchased power supplied from the power grid 2 to the load 4 from the power receiving board 20 by communicating with the power receiving board 20 via, for example, the communication line 31. Then, the control unit 60 acquires information on the magnitude of the current power generation of the solar panel 12 from the power conversion device 14 by communicating with the power conversion device 14 via, for example, the communication line 32.

[0075] After acquiring each piece of information, the control unit 60 predicts the power generation of the solar panel 12 after a predetermined time based on the information on the magnitude of the current power generation of the solar panel 12 (step S104 in FIG. 2). As described above, the control unit 60 may predict the power generation of the solar panel 12 after a predetermined time based on the information on the magnitude of the current power generation of the solar panel 12 and the information on the predicted amount of power generation of the solar panel 12.

[0076] Further, after acquiring each piece of information, the control unit 60 sets a limit threshold for the magnitude of the power supplied from the power conversion device 14 to the load 4 based on the information on the magnitude of the power required by the load 4 (step S105 in FIG. 2). For example, the control unit 60 stops the operation of the power conversion device 14 when the magnitude of the power currently supplied from the power conversion device 14 to the load 4 exceeds the limit threshold based on the information on the magnitude of the purchased power supplied from the power grid 2 to the load 4. Note that steps S104 and S105 may be performed in any order. The setting of the limit threshold may be performed before the prediction of the generated power, or may be performed substantially simultaneously with the prediction of the generated power.

[0077] After performing the prediction of the generated power and the setting of the limit threshold, the control unit 60 determines whether the maximum magnitude of the power that can be supplied from the power conversion device 14 to the load 4 based on the predicted generated power of the solar panel 12 after a predetermined time is greater than or equal to the limit threshold (step S106 in FIG. 2).

[0078] When the maximum magnitude of the power that can be supplied from the power conversion device 14 to the load 4 based on the predicted generated power of the solar panel 12 after a predetermined time is less than the limit threshold, the control unit 60 performs control without output limitation. In the control without output limitation, the control unit 60 supplies the maximum magnitude of the power that can be supplied based on the current generated power of the solar panel 12 from the power conversion device 14 to the load 4 by inputting a control signal indicating the execution of the control without output limitation to the power conversion device 14 (step S107 in FIG. 2).

[0079] On the other hand, when the maximum magnitude of the power that can be supplied from the power conversion device 14 to the load 4 based on the predicted generated power of the solar panel 12 after a predetermined time is greater than or equal to the limit threshold, the control unit 60 performs control with output limitation.

[0080] In the control with output limitation, the control unit 60 first determines whether the trend of the change in the power required by the load 4 is an increasing trend or a decreasing trend (step S108 in FIG. 2).

[0081] When it is in an upward trend, the control unit 60 sets a target value by using a first set value and subtracting the first set value from the magnitude of the power required by load 4 at the current time (step S109 in FIG. 2).

[0082] Also, when it is in an upward trend, the control unit 60 sets a first control period (step S110 in FIG. 2). Note that steps S109 and S110 may be in any order.

[0083] On the other hand, when it is in a downward trend, the control unit 60 sets a target value by using a second set value larger than the first set value and subtracting the second set value from the magnitude of the power required by load 4 at the current time (step S111 in FIG. 2).

[0084] Also, when it is in a downward trend, the control unit 60 sets a second control period longer than the first control period (step S112 in FIG. 2). Similar to the upward trend, steps S111 and S112 may be in any order.

[0085] After setting the target value, the control unit 60 detects a disturbance in the generated power of the solar panel 12 (step S113 in FIG. 2). When the control unit 60 detects a disturbance in the generated power, it sets a third control period shorter than the first control period (step S114 in FIG. 2). Note that the detection of the disturbance in the generated power may be performed, for example, before setting the target value in the control with output limitation. The timing for detecting the disturbance in the generated power is not limited to the above and may be at any timing.

[0086] After setting the target value and the control period, the control unit 60 inputs a control signal representing the set target value to the power conversion device 14, thereby supplying power of a magnitude corresponding to the target value from the power conversion device 14 to load 4 (step S115 in FIG. 2).

[0087] After receiving an input of a control signal representing control without output limitation or a control signal representing a target value, the control unit 60 returns to the process of step S101. Hereinafter, the control unit 60 repeats the processes of steps S101 to S115. At this time, the control unit 60 operates in any one of the first control cycle, the second control cycle, the third control cycle set in the control with output limitation, and the control cycle of the control without output limitation. The control cycle of the control without output limitation is set to the same cycle as the second control cycle, for example, as described above.

[0088] FIG. 3 is a graph schematically showing an example of the operation of the photovoltaic power generation system according to the embodiment. FIG. 3 schematically shows an example of each of the load power W (the magnitude of the power required by the load 4), the supply power Pa (the magnitude of the power supplied from the power conversion device 14 to the load 4), the predicted value Pb of the maximum power that can be supplied from the power conversion device 14 to the load 4, and the reference value Pc of the magnitude of the power supplied from the power conversion device 14 to the load 4 when performing the conventional load following control.

[0089] The vertical axis of FIG. 3 represents the magnitude of the power. The horizontal axis of FIG. 3 represents time. That is, FIG. 3 schematically shows an example of the temporal change in the magnitude of each power. Also, FIG. 3 schematically shows an example in the case where there is a rapid fluctuation in the load power W. In FIG. 3, for example, in the load 4 such as a factory, during the lunch break time period, the load power W rapidly decreases, and during the time period after the lunch break, the load power W rapidly increases is schematically shown.

[0090] As shown in FIG. 3, in the time period when the power generation power of the solar panel 12 in the morning is low, the predicted value Pb of the maximum power that can be supplied from the power conversion device 14 to the load 4 becomes lower than the limit threshold value (for example, times t11 to t12 in FIG. 3). Therefore, in this case, the control unit 60 of the output control device 16 controls the operation of the power conversion device 14 by the control without output limitation.

[0091] When the limit threshold is set to a value greater than the magnitude of the power at which the reverse power relay 26 detects a sign of reverse power flow, when performing control without output limitation, the reverse power relay 26 detects a sign of reverse power flow (for example, at time t12 in FIG. 3). Even when the reverse power relay 26 detects a sign of reverse power flow, the control unit 60 continues the control without output limitation until the predicted value Pb becomes equal to or greater than the limit threshold.

[0092] The predicted value Pb may exceed the load power W in response to an increase in the power generation of the solar panel 12 (for example, at time t14 in FIG. 3). In this case, the predicted value Pb becomes equal to or greater than the limit threshold before exceeding the load power W (for example, at time t13 in FIG. 3).

[0093] In response to the predicted value Pb becoming equal to or greater than the limit threshold, the control unit 60 performs control with output limitation. When the tendency of the change in the load power W is an increasing tendency, the control unit 60 sets the target value using the first set value so that the target value approaches the load power W as closely as possible, and sets the first control period to perform faster control (for example, from time t13 to t15 in FIG. 3).

[0094] When the tendency of the change in the load power W changes from an increasing tendency to a decreasing tendency, the control unit 60 sets the target value using the second set value, separates the target value from the load power W more than in the increasing tendency to suppress the occurrence of reverse power flow, and sets the second control period to perform slower control than in the increasing tendency (for example, from time t15 to t16 in FIG. 3).

[0095] When the tendency of the change in the load power W changes again from a decreasing tendency to an increasing tendency, the control unit 60 sets the target value using the first set value and sets the first control period (for example, from time t16 to t17 in FIG. 3).

[0096] In response to the power generation of the solar panel 12 decreasing in the evening time zone and the predicted value Pb becoming less than the limit threshold, the control unit 60 switches back from the control with output limitation to the control without output limitation (for example, at time t17 in FIG. 3).

[0097] As shown in FIG. 3, in the reference value Pc of the conventional load following control, in order to suppress the occurrence of reverse power flow, the set value of the power purchased from the power grid 4 is set relatively large. In the conventional load following control, for example, the set value of the purchased power is set so that the magnitude of the power supplied from the power conversion device 14 to the load 4 is smaller than the magnitude of the power at which a sign of reverse power flow is detected by the reverse power relay 26. Therefore, with the reference value Pc, it is not possible to control up to the vicinity of the load power W compared to the supply power Pa. Also, in the conventional load following control, a temporary delay occurs with respect to changes in the power generation of the solar panel 12.

[0098] On the other hand, in the solar power generation system 10 and the output control device 16 according to the present embodiment, the control unit 60 predicts the power generation of the solar panel 12 after a predetermined time, and sets a limit threshold for the magnitude of the power supplied from the power conversion device 14 to the load 4. When the maximum magnitude of the power that can be supplied from the power conversion device 14 to the load 4 based on the predicted power generation of the solar panel 12 after the predetermined time is less than the limit threshold, control without output limitation is performed, and when it is equal to or greater than the limit threshold, control with output limitation is performed.

[0099] In the solar power generation system 10 and the output control device 16 according to the present embodiment, by predicting the power generation, compared to the conventional load following control that does not predict the power generation, the controllability of the magnitude of the power supplied from the power conversion device 14 to the load 4 with respect to the magnitude of the power required by the load 4 can be further enhanced. As a result, in the solar power generation system 10 and the output control device 16 according to the present embodiment, compared to the conventional load following control, it is possible to set the limit threshold closer to the magnitude of the power required by the load 4 while suppressing the occurrence of reverse power flow. For example, it becomes possible to set the limit threshold to a value larger than the magnitude of the power at which a sign of reverse power flow is detected by the reverse power relay 26. Therefore, in the solar power generation system 10 and the output control device 16 according to the present embodiment, it is possible to further suppress the power purchased from the power grid 2 side while suppressing the occurrence of reverse power flow.

[0100] FIG. 4 is a graph schematically showing an example of another operation of the photovoltaic power generation system according to the embodiment. FIG. 4 schematically shows an example in which the load power W is stable, but the power generation power of the solar panel 12 fluctuates due to the influence of clouds or the like. In FIG. 4, the predicted value Pb is substantially the same as the supply power Pa.

[0101] As shown in FIG. 4, in this example, the control unit 60 performs control without output limitation during a period in which the predicted value Pb is lower than the limit threshold (for example, times t21 to t22, t23 to t24, t25 to t26, t27 to t28 in FIG. 4), and performs control with output limitation every time the predicted value Pb approaches the load power W and becomes equal to or higher than the limit threshold (for example, times t22 to t23, t24 to t25, t26 to t27 in FIG. 4).

[0102] Also in this example, with the reference value Pc of the conventional load following control, a temporary delay occurs with respect to the change in the power generation power of the solar panel 12, and the control cannot reach the vicinity of the load power W compared to the supply power Pa.

[0103] As described above, in the photovoltaic power generation system 10 and the output control device 16 according to the present embodiment, even when the power generation power of the solar panel 12 fluctuates and the predicted value Pb repeatedly approaches and separates from the load power W, compared to the conventional load following control, it is possible to suppress the occurrence of reverse power flow and further suppress the power purchase power from the power system 2 side.

[0104] FIG. 5 is a graph schematically showing an example of another operation of the photovoltaic power generation system according to the embodiment. FIG. 5 schematically shows an example in which an upward disturbance occurs in the power generation power of the solar panel 12.

[0105] As shown in FIG. 5, in this example, during a period in which the control unit 60 performs control with output limitation (for example, times t31 to t34 in FIG. 5), an upward disturbance occurs in the power generation power of the solar panel 12 (for example, time t32 in FIG. 5).

[0106] When the control unit 60 detects a disturbance in the generated power, it sets a third control cycle shorter than the first control cycle (for example, at times t32 to t33 in FIG. 5). Thereby, the control unit 60 can perform faster control and enhance the controllability of the magnitude of the power supplied from the power conversion device 14 to the load 4 with respect to the magnitude of the power required by the load 4. Therefore, even when an upward disturbance occurs in the generated power of the solar panel 12, the occurrence of reverse power flow can be more appropriately suppressed.

[0107] Also, in this example as well, in the reference value Pc of the conventional load following control, there is a temporary delay with respect to the change in the generated power of the solar panel 12, and it cannot be controlled up to the vicinity of the load power W compared to the supplied power Pa.

[0108] As described above, in the solar power generation system 10 and the output control device 16 according to this embodiment, even when an upward disturbance occurs in the generated power of the solar panel 12, compared to the conventional load following control, while suppressing the occurrence of reverse power flow, the power purchased from the power grid 2 side can be further suppressed.

[0109] FIG. 6 is a graph schematically showing an example of another operation of the solar power generation system according to the embodiment. FIG. 6 schematically shows an example in which an upward disturbance occurs in the generated power of the solar panel 12.

[0110] As shown in FIG. 6, in this example, during the period when the control unit 60 is performing control with an output limit (for example, at times t41 to t44 in FIG. 6), a downward disturbance has occurred in the generated power of the solar panel 12 (for example, at time t42 in FIG. 6).

[0111] When the control unit 60 detects a disturbance in the generated power, it sets a third control cycle shorter than the first control cycle (for example, from time t42 to t43 in FIG. 6). Thereby, the control unit 60 can perform faster control and enhance the controllability of the magnitude of the power supplied from the power conversion device 14 to the load 4 with respect to the magnitude of the power required by the load 4. Therefore, even when a downward disturbance occurs in the generated power of the solar panel 12, the followability of the supplied power Pa can be enhanced, and an increase in the power purchased from the power grid 2 side can be more appropriately suppressed.

[0112] Also, in this example as well, with the reference value Pc of the conventional load following control, a temporary delay occurs with respect to the change in the generated power of the solar panel 12, and the control cannot reach near the load power W compared to the supplied power Pa.

[0113] As described above, in the solar power generation system 10 and the output control device 16 according to the present embodiment, even when a downward disturbance occurs in the generated power of the solar panel 12, compared with the conventional load following control, while suppressing the occurrence of reverse power flow, the power purchased from the power grid 2 side can be further suppressed.

[0114] In the above embodiment, as an example of a distributed power system, a solar power generation system 10 using a solar panel 12 as a distributed power source is shown. The distributed power source is not limited to the solar panel 12, and may be, for example, a wind power generator, a geothermal power generator, or the like. The distributed power source may be any power source capable of supplying the generated power. The power supplied by the distributed power source is not limited to DC power, and may be AC power or the like. The distributed power system is not limited to the solar power generation system 10, and may be any system using any distributed power source.

[0115] This embodiment includes the following aspects. (Appendix 1) An output control device used in a fully self-consumption type distributed power system that suppresses power purchase from a power grid to a load by converting power supplied from a distributed power source into AC power corresponding to the load by a power conversion device and supplying the converted AC power to the load, A communication unit that receives inputs of information on the magnitude of the power required by the load and information on the magnitude of the current power generation of the distributed power source; A control unit that controls the operation of power conversion by the power conversion device based on information on the magnitude of the power required by the load and information on the magnitude of the current power generation of the distributed power source; Comprising: The control unit: Based on information on the magnitude of the current power generation of the distributed power source, predicts the power generation of the distributed power source after a predetermined time, and Based on information on the magnitude of the power required by the load, sets a limit threshold for the magnitude of the power supplied from the power conversion device to the load, When the maximum magnitude of the power that can be supplied from the power conversion device to the load based on the predicted power generation of the distributed power source after a predetermined time is less than the limit threshold, performs control without output limitation to control the operation of the power conversion device to output the maximum magnitude of power that can be supplied based on the current power generation of the distributed power source, When the maximum magnitude of the power that can be supplied from the power conversion device to the load based on the predicted power generation of the distributed power source after a predetermined time is greater than or equal to the limit threshold, sets a target value corresponding to the magnitude of the power required by the load at the current time, and controls the operation of the power conversion device to output power of a magnitude corresponding to the target value, thereby performing control with output limitation to limit the magnitude of the power supplied from the power conversion device to the load to the target value. An output control device.

[0116] (Appendix 2) In the control with output limitation, when the trend of change in the power required by the load is an increasing trend, the control unit sets the target value by subtracting a first set value from the magnitude of the power required by the load at the current time. When the trend of change in the power required by the load is a decreasing trend, the control unit sets the target value by subtracting a second set value greater than the first set value from the magnitude of the power required by the load at the current time. The output control device according to Supplementary Note 1.

[0117] (Supplementary Note 3) The control unit controls the operation of the power conversion device at each predetermined control cycle. In the control with output limitation, when the trend of change in the power required by the load is an increasing trend, a first control cycle is set. When the trend of change in the power required by the load is a decreasing trend, a second control cycle longer than the first control cycle is set. The output control device according to Supplementary Note 2.

[0118] (Supplementary Note 4) The control unit controls the operation of the power conversion device at each predetermined control cycle. In the control with output limitation, when a disturbance in the generated power of the distributed power source is detected, the control cycle is shortened. The output control device according to any one of Supplementary Notes 1 to 3.

[0119] (Supplementary Note 5) The distributed power source system has a reverse power relay that detects reverse power flow from the power conversion device toward the power grid side and detects a sign of reverse power flow when the power purchased from the power grid becomes equal to or less than a predetermined value. The limit threshold value is set to a value greater than the magnitude of the power at which a sign of reverse power flow is detected by the reverse power relay. The output control device according to any one of Supplementary Notes 1 to 4.

[0120] (Supplementary Note 6) A fully self-consumption type distributed power source system that suppresses power purchase from the power grid by converting the power supplied from a distributed power source into AC power corresponding to a load by a power conversion device and supplying the converted AC power to the load, A distributed power source that generates power and supplies the generated power, A power conversion device that converts the power supplied from the distributed power source into AC power corresponding to the load and supplies the converted AC power to the load, An output control device that controls the operation of power conversion by the power conversion device, Comprising, The output control device, A communication unit that receives inputs of information on the magnitude of power required by the load and information on the magnitude of the current power generation of the distributed power source, A control unit that controls the operation of power conversion by the power conversion device based on information on the magnitude of power required by the load and information on the magnitude of the current power generation of the distributed power source, Having, The control unit, Based on information on the magnitude of the current power generation of the distributed power source, predicts the power generation of the distributed power source after a predetermined time, and Based on information on the magnitude of power required by the load, sets a limit threshold for the magnitude of power supplied from the power conversion device to the load, When the magnitude of the maximum power that can be supplied from the power conversion device to the load based on the predicted power generation of the distributed power source after a predetermined time is less than the limit threshold, performs control without output limitation to control the operation of the power conversion device to output the maximum magnitude of power that can be supplied based on the current power generation of the distributed power source, When the magnitude of the maximum power that can be supplied from the power conversion device to the load based on the generated power of the distributed power source after a predicted predetermined time is equal to or greater than the limit threshold value, a target value corresponding to the magnitude of the power required by the load at the current time is set, and the operation of the power conversion device is controlled so as to output power of a magnitude corresponding to the target value, thereby performing control with output limitation that limits the magnitude of the power supplied from the power conversion device to the load to the target value. A distributed power source system.

[0121] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0122] 2…Power grid, 4…Load, 6…Transformer, 8…On-site grid, 10…Photovoltaic power generation system (distributed power source system), 12…Photovoltaic panel (distributed power source), 14…Power conversion device, 16…Output control device, 18…Monitoring device, 20…Switchboard, 22, 24…Power meter, 26…Reverse power relay, 30~33…Communication line, 35~37…Signal line, 50…Conversion circuit, 51…Control unit, 52, 53…Communication unit, 54…Input unit, 60…Control unit, 61~63…Communication unit, 64…Input unit

Claims

Claim 1 An output control device used in a fully self-consumption distributed power supply system that suppresses power purchase from the power grid by converting the power supplied from a distributed power source into AC power corresponding to a load by a power conversion device and supplying the converted AC power to the load, comprising: a communication unit that receives inputs of information on the magnitude of the power required by the load and information on the magnitude of the current power generation of the distributed power source; a control unit that controls the operation of power conversion by the power conversion device based on information on the magnitude of the power required by the load and information on the magnitude of the current power generation of the distributed power source; wherein the control unit predicts the power generation of the distributed power source after a predetermined time based on information on the magnitude of the current power generation of the distributed power source, and sets a limit threshold for the magnitude of the power supplied from the power conversion device to the load based on information on the magnitude of the power required by the load, when the maximum magnitude of the power that can be supplied from the power conversion device to the load based on the predicted power generation of the distributed power source after a predetermined time is less than the limit threshold, performs control without output limitation to control the operation of the power conversion device to output the maximum magnitude of power that can be supplied based on the current power generation of the distributed power source, when the maximum magnitude of the power that can be supplied from the power conversion device to the load based on the predicted power generation of the distributed power source after a predetermined time is equal to or greater than the limit threshold, sets a target value corresponding to the magnitude of the power required by the load at the current time, and controls the operation of the power conversion device to output power of a magnitude corresponding to the target value, thereby performing control with output limitation to limit the magnitude of the power supplied from the power conversion device to the load to the target value. An output control device. Claim 2 In the control with output limitation, the control unit sets the target value by subtracting a first set value from the magnitude of the power required by the load at the current time when the trend of change in the power required by the load is an upward trend, and subtracts a second set value greater than the first set value from the magnitude of the power required by the load at the current time when the trend of change in the power required by the load is a downward trend. The output control device according to Claim 1. Claim 3 The control unit controls the operation of the power conversion device at each predetermined control cycle, and in the control with output limitation, when the tendency of the change in the power required by the load is an increasing tendency, a first control cycle is set, and when the tendency of the change in the power required by the load is a decreasing tendency, a second control cycle longer than the first control cycle is set. The output control device according to claim 2.

4. The control unit controls the operation of the power conversion device at each predetermined control cycle, and in the control with output limitation, when detecting a disturbance in the generated power of the distributed power source, shortens the control cycle. The output control device according to claim 1.

5. The distributed power source system includes a reverse power relay that detects reverse power flow from the power conversion device toward the power grid side and detects a sign of reverse power flow when the power purchased from the power grid becomes equal to or less than a predetermined value. The limit threshold value is set to a value larger than the magnitude of the power at which a sign of reverse power flow is detected by the reverse power relay. The output control device according to claim 1.

6. A fully self-consumption type distributed power source system that converts the power supplied from a distributed power source into AC power corresponding to a load by a power conversion device and supplies the converted AC power to the load, thereby suppressing power purchase from the power grid to the load. A distributed power source that generates power and supplies the generated power. A power conversion device that converts the power supplied from the distributed power source into AC power corresponding to the load and supplies the converted AC power to the load. An output control device that controls the operation of power conversion by the power conversion device. Comprising: The output control device includes: A communication unit that receives inputs of information on the magnitude of the power required by the load and information on the magnitude of the currently generated power of the distributed power source. A control unit that controls the operation of power conversion by the power conversion device based on information on the magnitude of the power required by the load and information on the magnitude of the currently generated power of the distributed power source. Having: The control unit includes: Based on information on the magnitude of the currently generated power of the distributed power source, predicts the generated power of the distributed power source after a predetermined time, and Based on information on the magnitude of the power required by the load, sets a limit threshold value for the magnitude of the power supplied from the power conversion device to the load. When the magnitude of the maximum power that can be supplied from the power conversion device to the load based on the generated power of the distributed power source after the predicted predetermined time is less than the limit threshold, control without output limitation is performed to control the operation of the power conversion device so as to output the maximum magnitude of power that can be supplied based on the current generated power of the distributed power source. When the magnitude of the maximum power that can be supplied from the power conversion device to the load based on the generated power of the distributed power source after the predicted predetermined time is greater than or equal to the limit threshold, a target value corresponding to the magnitude of the power required by the load at the current time is set, and by controlling the operation of the power conversion device so as to output the power of the magnitude corresponding to the target value, a distributed power source system that performs control with output limitation that limits the magnitude of the power supplied from the power conversion device to the load to the target value.

Images