Output control device and distributed power supply system

Abstract

The present invention provides an output control device and a distributed power system that suppress the occurrence of reverse power flow and enable more appropriate utilization of power generated by distributed power sources. [Solution] The system includes a communication unit that receives input of information on the amount of power required by the load and information on the current amount of power generated by the distributed power source; a storage unit that stores a power generation prediction model that associates weather information at the location where the distributed power source is installed with the amount of power generated by the distributed power source; and a control unit that acquires weather forecast data representing the weather forecast result at the location where the distributed power source is installed from an external device and controls the operation of power conversion by the power converter. The control unit predicts the amount of power generated by the distributed power source after a predetermined time based on the weather forecast data and the power generation prediction model, and an output control device is provided that controls the operation of power conversion by the power converter by feedforward control based on the predicted amount of power generated.

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 power conversion by the power conversion device.

[0003] In addition, the 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 in the power conversion device in response to detecting the occurrence of reverse power flow.

[0004] In a fully self-consumption type distributed power system, it is desirable to make the most 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.

[0005] However, with follow-up control, there is a temporary delay in the amount of power supplied to the load in response to fluctuations in the power generated by distributed power sources due to weather changes, etc. Therefore, there is a possibility that the control may not be able to keep up when the power generated changes rapidly. For example, if the power generated increases rapidly, the control may not be able to keep up, and reverse power flow may occur. Consequently, the reverse power relay may detect the reverse power flow and stop the power conversion operation by the power converter. Also, for example, if the power generated increases rapidly, the control may not be able to keep up, and the generated power may be wasted.

[0006] If the power converter stops its power conversion operation in response to the detection of reverse power flow by the reverse power relay, the amount of electricity purchased from the power grid will increase, leading to higher electricity bills. Furthermore, there are concerns that the sudden fluctuations in power, voltage, and current may cause malfunctions in load equipment.

[0007] Therefore, in a fully self-consumption type distributed power generation system, and in the output control devices used therein, it is desirable to suppress the occurrence of reverse power flow and enable more appropriate utilization of the power generated by the distributed power sources. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2022-188602 [Patent Document 2] Japanese Patent Publication No. 2023-23134 [Patent Document 3] Japanese Patent Publication No. 2023-86572 [Patent Document 4] Patent No. 7399363 [Overview of the project] [Problems that the invention aims to solve]

[0009] Embodiments of the present invention provide an output control device and a distributed power system that suppress the generation of reverse power flow and enable more appropriate utilization of power generated by distributed power sources. [Means for solving the problem]

[0010] According to an embodiment of the present invention, an output control device used in a fully self-consumption type distributed power system that suppresses the purchase of electricity from the power grid to a load by converting power supplied from a distributed power source into AC power corresponding to the load using a power converter and supplying the converted AC power to the load, comprises a communication unit that receives input of information on the amount of power required by the load and information on the current amount of power generated by the distributed power source, and stores a power generation prediction model that stores weather information at the location where the distributed power source is installed and the amount of power generated by the distributed power source in association, thereby enabling the prediction of the amount of power generated by the distributed power source based on the weather forecast for the location where the distributed power source is installed. The system includes a storage unit and a communication unit that communicates with an external device to acquire weather forecast data representing the weather forecast results for the location where the distributed power supply is installed from the external device, and a control unit that controls the operation of power conversion by the power converter based on information on the amount of power required by the load, information on the current amount of power generated by the distributed power supply, the power generation forecast model, and the weather forecast data. The control unit predicts the amount of power generated by the distributed power supply after a predetermined time based on the weather forecast data and the power generation forecast model, and an output control device that controls the operation of power conversion by the power converter by feedforward control based on the predicted amount of power generated. [Effects of the Invention]

[0011] An output control device and a distributed power system are provided that suppress the occurrence of reverse power flow and enable more appropriate utilization of power generated by distributed power sources. [Brief explanation of the drawing]

[0012] [Figure 1]This is a block diagram schematically representing a solar power generation system according to an embodiment. [Figure 2] This is a flowchart schematically illustrating an example of the operation of a solar power generation system according to the embodiment. [Modes for carrying out the invention]

[0013] Each embodiment will be described below with reference to the drawings. Please note that the drawings are schematic or conceptual, and the relationships between the thickness and width of each part, as well as the ratios of the sizes of the parts, are not necessarily identical to those of reality. Furthermore, even when representing the same part, the dimensions and ratios may differ between drawings. In this specification and in each figure, elements similar to those described above are denoted by the same reference numerals, and detailed explanations are omitted as appropriate.

[0014] Figure 1 is a block diagram schematically representing a solar power generation system according to an embodiment. As shown in Figure 1, the photovoltaic power generation system 10 (distributed power system) comprises a photovoltaic panel 12 (distributed power source), a power converter 14, an output control device 16, a monitoring device 18, a power receiving panel 20, and a power meter 22.

[0015] The solar power generation system 10 is connected to the power grid 2 and load 4. The solar power generation system 10 is a fully self-consumption type system that reduces the purchase of electricity from the power grid 2 to load 4 by supplying the electricity generated by the solar panels 12 to load 4. The electricity from power grid 2 is AC electricity. Load 4 is an AC load. In other words, load 4 is a consumer.

[0016] The solar panel 12 generates electricity and also supplies the generated electricity. The solar panel 12 generates electricity by converting the light energy of sunlight into electrical energy using the photovoltaic effect. The electricity generated by the solar panel 12 is DC electricity. The solar panel 12 supplies the generated DC electricity to the power converter 14.

[0017] The power conversion device 14 is connected to the solar panel 12 and is also connected to the load 4 via the transformer 6, the in-plant power system 8, etc. The power conversion device 14 converts the power supplied from the solar panel 12 into AC power corresponding to the load 4 and supplies the converted AC power to the load 4.

[0018] The load 4 is connected to the power conversion device 14 and is also connected to the power grid 2 via the in-plant power system 8, the switchboard 20, etc. The load 4 receives the power generated by the solar panel 12 from the power conversion device 14 and receives the power supply of the insufficient part of the power generated by the solar panel 12 for the required power from the power grid 2. The power conversion device 14 is configured to suppress the power purchase from the power grid 2 by maximizing the utilization of the power generated by the solar panel 12.

[0019] 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 display of the acquired information, etc., so that the administrator of the solar power generation system 10 can monitor whether the power conversion device 14 and the output control device 16 are operating normally.

[0020] ​​​​​​​​​The power receiving panel 20 includes, for example, a power meter 24 and a reverse power relay 26 (RPR). The power meter 24 measures the power supplied from the power system 2 to the load 4. In other words, the power supplied from the power system 2 to the load 4 is the difference between the power required by the load 4 and the power supplied to the load 4 from the solar panel 12.

[0023] The power receiving panel 20 is connected to the output control device 16, for example, via a communication line 31. The power receiving panel 20 communicates with the output control device 16 via the communication line 31 and inputs the measurement results of the power meter 22 and the power meter 24 to the output control device 16. The measurement results of the power meter 22 may be input directly from the power meter 22 to the output control device 16 without going through the power receiving panel 20. In addition, the power supplied from the power system 2 to the load 4 may be calculated on the output control device 16 side based on the measurement results, for example, by measuring the voltage and current values ​​at the interconnection point.

[0024] The reverse power relay 26 detects reverse power flow from the power converter 14 towards the power system 2. The power converter 14 is connected to the power system 2 via the transformer 6, the premises system 8, and the power receiving panel 20. Therefore, if the power generated by the solar panels 12 exceeds the power consumed by the load 4, some of the output power of the power converter 14 may flow to the power system 2. The reverse power relay 26 detects the occurrence of such reverse power flow and performs an operation to suppress it.

[0025] The reverse power relay 26 is connected to the power converter 14 via a signal line 35. The reverse power relay 26 inputs a reverse power flow detection signal to the power converter 14 in response to the detection of reverse power flow. For example, the reverse power relay 26 inputs a reverse power flow detection signal to the power converter 14 if the reverse power flow condition continues for a predetermined time or longer. In other words, the reverse power relay 26 detects the occurrence of reverse power flow if the reverse power flow condition continues for a predetermined time or longer. The predetermined time is, for example, about 0.5 seconds to 2 seconds.

[0026] The power converter 14 stops outputting AC power to the load 4 in response to the input of a reverse power flow detection signal. In this way, the reverse power relay 26 detects reverse power flow and stops the operation of the power converter 14 that outputs AC power to the load 4 in response to the detection of reverse power flow. This prevents the reverse power relay 26 from continuing to flow reverse power to the power system 2. In other words, the reverse power relay 26 performs the operation of stopping the power converter 14 as an operation to suppress reverse power flow.

[0027] The reverse power relay 26 may, for example, have a circuit breaker that opens and closes the connection to the power system 2. The reverse power relay 26 may suppress reverse power flow by stopping the operation of the power converter 14 and opening the circuit breaker in response to the detection of reverse power flow. The operation to suppress reverse power flow may also be the operation of stopping the operation of the power converter 14 and opening the circuit breaker. The reverse power relay 26 does not necessarily have to be installed in the power receiving panel 20. The reverse power relay 26 may be installed separately from the power receiving panel 20.

[0028] The power converter 14 includes a conversion circuit 50, a control unit 51, communication units 52 and 53, and an input unit 54.

[0029] 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 the power conversion by the conversion circuit 50.

[0030] The communication unit 52 is connected to the control unit 51 and also 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 control signals to the communication unit 52 via the communication line 32 to control the operation of the power converter 14. By communicating with the output control device 16, the communication unit 52 receives control signals from the output control device 16 and inputs the input control signals to the control unit 51. The control unit 51 controls the operation of the conversion circuit 50 based on the control signals input from the communication unit 52. This makes it possible to control the AC power output from the conversion circuit 50 (power converter 14) in accordance with the control signals input from the output control device 16.

[0031] The communication unit 53 is connected to the control unit 51 and also 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.

[0032] The control unit 51 communicates with the monitoring device 18 via the communication unit 53 and the communication line 33 to transmit information to the monitoring device 18 for monitoring the operation of the power converter 14. The output control device 16 communicates with the monitoring device 18 via the communication line 33 to transmit information to the monitoring device 18 for monitoring the operation of the output control device 16. In this way, the monitoring device 18 monitors the operation of the power converter 14 and the output control device 16 by communicating with them 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 converter 14, control communication and monitoring communication may be performed by a single communication unit.

[0033] 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 a reverse power flow detection signal, which is received from the reverse power relay 26 via the signal line 35, to the control unit 51. In response to the input of the reverse power flow detection signal from the input unit 54, the control unit 51 stops the power conversion operation by the conversion circuit 50.

[0034] In this manner, the reverse power relay 26 is connected to the input unit 54, for example, via the signal line 35, and stops the operation of the power converter 14 by inputting a reverse power flow detection signal to the input unit 54 in response to the detection of the occurrence of reverse power flow. As a result, as described above, the operation of the power converter 14 can be stopped in response to the detection of the occurrence of reverse power flow by the reverse power relay 26, thereby suppressing reverse power flow to the power system 2 side.

[0035] Communication via communication lines 30-33 requires communication circuits such as communication units 52 and 53. Communication via communication lines 30-33 allows for the transmission and reception of various types of information, such as control signals representing the output power of the power converter 14. On the other hand, communication via communication lines 30-33 suffers from delays due to processing by communication units 52 and 53. Communication via communication lines 30-33 conforms to communication standards such as Ethernet and RS485. In other words, communication units 52 and 53 are communication circuits conforming to predetermined communication standards.

[0036] Communication via signal line 35 can only handle binary inputs, such as the input and deactivation of a reverse power flow detection signal. The detection signal has two states: a reverse power flow detection state and a non-detection state. On the other hand, communication via signal line 35 can suppress delays caused by processing in the communication unit, allowing for faster input of each signal compared to communication via communication lines 30-33. Communication via signal line 35 is, for example, communication by switching the contacts of a relay on and off. Input unit 54 is a circuit that uses contact input, which is faster than communication via communication units 52 and 53. Input unit 54 is, for example, an input / output terminal (IO terminal). Signal line 35 is, for example, a hardwire.

[0037] In the solar power generation system 10, the power output from the power converter 14 (conversion circuit 50) is controlled by communication using communication lines 30-33. On the other hand, to stop the operation of the power converter 14 in response to the detection of reverse power flow by the reverse power relay 26, communication using signal line 35 is used. As a result, stopping the operation of the power converter 14 in response to the detection of reverse power flow can be done faster than communication using communication lines 30-33. Thus, the solar power generation system 10 uses a contact input that is faster than communication using communication lines 30-33 to stop the operation of the power converter 14 in response to the detection of reverse power flow.

[0038] The output control device 16 includes a control unit 60, communication units 61 to 63, and a storage unit 64. The communication unit 61 is connected to the control unit 60 and also to the power receiving panel 20 via a communication line 31. The communication unit 61 communicates with the power receiving panel 20 via the communication line 31, receiving input from the power receiving panel 20 of the measurement results of the power meter 22 and the power meter 24, and inputting the input measurement results of the power meter 22 and the power meter 24 to the control unit 60. In other words, the communication unit 61 communicates with the power receiving panel 20, receiving input of information on the amount of power required by the load 4 and information on the amount of purchased power supplied to the load 4 from the power system 2, and inputting the input information on the amount of power required by the load 4 and the amount of purchased power supplied to the load 4 from the power system 2 to the control unit 60.

[0039] Furthermore, information regarding the amount of power required by load 4, and information regarding the amount of purchased power supplied to load 4 from power system 2, is not limited to the power receiving panel 20, but may also be obtained from other devices, such as the monitoring device 18. The configuration for obtaining information regarding the amount of power required by load 4 and the amount of purchased power supplied to load 4 from power system 2 is not limited to the above, and may be any configuration that allows each piece of information to be appropriately obtained through communication by the communication unit 61.

[0040] The communication unit 62 is connected to the control unit 60 and also to the communication unit 52 of the power converter 14 via the communication line 32. The communication unit 62 receives control signals from the control unit 60 to control the operation of the power converter 14. The communication unit 62 communicates with the communication unit 52 of the power converter 14 via the communication line 32, thereby inputting the control signals received from the control unit 60 to the communication unit 52 via the communication line 32. In other words, the communication unit 62 transmits control signals to the communication unit 52.

[0041] Furthermore, the communication unit 62 communicates with the communication unit 52 of the power converter 14 via the communication line 32, receiving information regarding the status monitoring of the power converter 14 from the power converter 14, and inputting the input information regarding the status monitoring to the control unit 60. The information regarding the status monitoring includes information on the current amount of power generated by the solar panel 12. In other words, the communication unit 62 receives information on the current amount of power generated by the solar panel 12 by communicating with the communication unit 52, and inputs the input information on the current amount of power generated by the solar panel 12 to the control unit 60. The current amount of power generated by the solar panel 12 is, in other words, the amount of power that can be supplied to the load 4 from the power converter 14 at this moment. "This moment" refers, for example, to the time when the communication unit 52 and the communication unit 62 communicate (the time when the output control device 16 receives the input information on the amount of power generated).

[0042] Furthermore, information on the current power generation of the solar panel 12 is not limited to the power conversion device 14; it may also be obtained from another device, such as a monitoring device 18. The configuration for obtaining information on the current power generation of the solar panel 12 is not limited to the above; any configuration that allows for appropriate acquisition of information through communication by the communication unit 62 is acceptable.

[0043] The communication unit 63 is connected to the control unit 60 and also 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 to the monitoring device 18 for monitoring the operation of the output control device 16.

[0044] Furthermore, in the output control device 16, communication between each communication unit 61 to 63 may be performed by a single communication unit. The output control device 16 may have as few as one communication unit. The output control device 16 may receive input information on the amount of power required by the load 4, the amount of purchased electricity supplied to the load 4 from the power system 2, and the current amount of power generated by the solar panel 12 through a single communication unit. The configuration for receiving input information on the amount of power required by the load 4, the amount of purchased electricity supplied to the load 4 from the power system 2, and the current amount of power generated by the solar panel 12 may be any configuration that allows each piece of information to be appropriately received by at least one communication unit.

[0045] The memory unit 64 stores a power generation prediction model 64a that enables the prediction of the amount of power generated by the solar panels 12 based on the weather forecast for the location where the solar panels 12 (distributed power source) are installed, by associating weather information of the location where the solar panels 12 are installed with the amount of power generated by the solar panels 12. The memory unit 64 may be an external memory unit provided separately from the control unit 60 and connected to the control unit 60 so that information can be read and written, or it may be an internal memory unit provided within the control unit 60.

[0046] If the distributed power source is a solar panel 12, the weather information includes, for example, information on the amount of solar radiation at the location where the solar panel 12 is installed. The power generation prediction model 64a stores, for example, the magnitude of solar radiation and the magnitude of power generated by the solar panel 12 in association. This allows the power generation prediction model 64a to predict the magnitude of power generated by the solar panel 12 based on the predicted amount of solar radiation at any given time at the location where the solar panel 12 is installed.

[0047] However, meteorological information is not limited to solar radiation information. For example, the amount of power generated by the solar panels 12 also changes depending on the temperature of the solar panels 12. For this reason, meteorological information may also include, for example, temperature information and precipitation information. Meteorological information is not limited to the above, and may be any information that makes it possible to predict the amount of power generated by the solar panels 12 (distributed power source) based on the weather forecast for the location where the solar panels 12 are installed.

[0048] The power generation prediction model 64a is generated by machine learning (supervised learning) based on, for example, past weather information observed for the location where the solar panels 12 are installed, information on the past magnitude of power generated by the solar panels 12, information on the arrangement of the solar panels 12, and information on losses within the solar power generation system 10 (power generation equipment). For example, past weather information and information on the past magnitude of power generated may include data from the past several years. Based on the above information, the power generation prediction model 64a is generated as a model specific to each solar power generation system 10 (power generation equipment).

[0049] The power generation prediction model 64a is generated by the control unit 60 by inputting the above-mentioned information, for example, and stored in the storage unit 64. The control unit 60 has a function to generate the power generation prediction model 64a by machine learning based on the input information, for example. However, the power generation prediction model 64a may also be generated by an external device such as a monitoring device 18, and then stored in the storage unit 64 of the output control device 16 by inputting it via communication or a storage medium.

[0050] The control unit 60 communicates with an external device via the communication unit 63 to obtain weather forecast data representing the weather forecast results for the location where the solar panels 12 are installed. The external device is, for example, a server of a weather forecasting company that provides information on weather forecasts. The external device may also be, for example, a monitoring device 18. For example, the monitoring device 18 may obtain weather forecast data from a weather forecasting company, and the control unit 60 may obtain weather forecast data from the monitoring device 18 by communicating with the monitoring device 18. The communication unit 63 is a communication unit that communicates with the monitoring device 18, for example, and also communicates with external devices such as a server of a weather forecasting company. Note that the external device is not limited to the above and may be any device capable of obtaining weather forecast data by communication.

[0051] The control unit 60 controls the operation of the power conversion device 14 based on information regarding the amount of power required by the input load 4, information regarding the amount of purchased power supplied to the load 4 from the power system 2, information regarding the current amount of power generated by the solar panels 12, weather forecast data acquired from external equipment, and the power generation forecast model 64a stored in the memory unit 64.

[0052] The control unit 60 predicts the amount of power generated by the solar panels 12 after a predetermined time based on weather forecast data and power generation forecast model 64a, and controls the power conversion operation of the power converter 14 by feedforward control based on the predicted amount of power generated.

[0053] The control unit 60, for example, predicts the magnitude of the power generated by the solar panel 12 at the time of the next control cycle and controls the power converter 14 by feedforward control at each predetermined control cycle. The predetermined time is, for example, the time of one control cycle of the control unit 60.

[0054] The weather forecast data includes, for example, information on the predicted amount of solar radiation at a given time at the location where the solar panels 12 are installed, similar to the power generation forecast model 64a. The weather forecast data is, for example, data representing the temporal change in the predicted amount of solar radiation at the location where the solar panels 12 are installed.

[0055] The control unit 60 acquires a day's worth of weather forecast data at once, for example, during nighttime or early morning hours, and stores the acquired weather forecast data in the storage unit 64. In this case, the control unit 60 sequentially reads out the time data (solar radiation information) necessary for control from the weather forecast data stored in the storage unit 64 for each control cycle. The control unit 60 may also sequentially acquire the time data (solar radiation information) necessary for control by communicating with external equipment via the communication unit 63 for each control cycle.

[0056] In feedforward control, the control unit 60 first sets an upper limit for the amount of power supplied from the power converter 14 to the load 4 by subtracting a predetermined set value from the amount of power currently required by the load 4. After this, the control unit 60 determines whether the maximum amount of power that can be supplied from the power converter 14 to the load 4 is equal to or greater than the upper limit, based on the predicted amount of generated power.

[0057] If the control unit 60 determines that the power is below the upper limit, it generates a control signal to output the maximum amount of power that can be supplied from the power converter 14 to the load 4 based on the predicted amount of power generated. By inputting the generated control signal to the communication unit 52 of the power converter 14 via the communication line 32, the control unit 60 controls the operation of the power converter 14 so that it outputs the maximum amount of power that can be supplied from the power converter 14 to the load 4 based on the predicted amount of power generated.

[0058] This prevents wasted power generation, for example, when the generated power increases rapidly within a range below the upper limit between control cycles, by suppressing the output through control.

[0059] On the other hand, if the control unit 60 determines that the value is above the upper limit, it generates a control signal to output the upper limit, and inputs the generated control signal to the communication unit 52 of the power converter 14 via the communication line 32, thereby controlling the operation of the power converter 14 to output the upper limit.

[0060] This allows the amount of power supplied from the power converter 14 to the load 4 to be limited to the upper limit, even if, for example, the generated power increases rapidly between control cycles and the maximum amount of power that can be supplied from the power converter 14 to the load 4 exceeds the upper limit. This prevents, for example, the amount of power supplied from the power converter 14 to the load 4 from becoming greater than the power consumed by the load 4, thereby preventing reverse power flow.

[0061] Furthermore, when the control unit 60 controls the power converter 14 using feedforward control, it calculates the deviation between the current power generation of the solar panel 12 and the predicted power generation, based on information about the current power generation of the solar panel 12. More specifically, the predicted power generation is the power generation predicted in the previous control cycle. In other words, the control unit 60 calculates the deviation between the predicted value and the measured value of power generation at a predetermined time.

[0062] The control unit 60 then determines whether the calculated deviation is greater than or equal to a predetermined value. If the control unit 60 determines that it is less than the predetermined value, it continues to control the power converter 14 using feedforward control. On the other hand, if the control unit 60 determines that it is greater than or equal to the predetermined value, it determines that the prediction of generated power is significantly off, and switches from controlling the power converter 14 using feedforward control to controlling the power converter 14 using feedback control based on the current amount of generated power from the solar panel 12.

[0063] In feedback control, the control unit 60 determines whether the maximum amount of power that can be supplied from the power converter 14 to the load 4 is equal to or greater than the upper limit, based on the current amount of power generated by the solar panel 12.

[0064] If the control unit 60 determines that the current power generation is below the upper limit, it generates a control signal to output the maximum amount of power that can be supplied from the power converter 14 to the load 4 based on the current power generation of the solar panel 12. By inputting the generated control signal to the communication unit 52 of the power converter 14 via the communication line 32, the control unit 60 controls the operation of the power converter 14 so that it outputs the maximum amount of power that can be supplied from the power converter 14 to the load 4 based on the current power generation of the solar panel 12. For this reason, in feedback control, if the power generation increases rapidly within the range below the upper limit between control cycles, the output may be suppressed by the control, potentially wasting the generated power.

[0065] On the other hand, if the control unit 60 determines that the value is above the upper limit, it generates a control signal to output the upper limit, and inputs the generated control signal to the communication unit 52 of the power converter 14 via the communication line 32, thereby controlling the operation of the power converter 14 to output the upper limit.

[0066] This allows the control of the power converter 14 to be appropriately continued through feedback control even if the prediction of power generation is significantly off. Furthermore, during the feedback control period, the control unit 60 continues to calculate the deviation between the current power generation of the solar panel 12 and the predicted power generation, and to determine whether the calculated deviation is greater than or equal to a predetermined value. Then, when the deviation falls below the predetermined value, the control unit 60 switches back from feedback control to feedforward control.

[0067] The control unit 60, for example, shortens the control period in feedback control to a shorter period than the control period in feedforward control. The control period in feedback control is set to be shorter than the time it takes for the reverse power relay 26 to detect the occurrence of reverse power flow. The control period in feedback control is set to, for example, less than 2 seconds. This makes it possible to suppress the occurrence of reverse power flow due to a sudden increase in generated power during the control period, even when the power converter 14 is controlled by feedback control.

[0068] In feedforward control, the control period is set to, for example, about 1 minute (for example, 30 seconds to 2 minutes). This makes it possible to suppress, for example, the increase in the computational load of the control unit 60 associated with predicting power generation. Also, for example, it is possible to lengthen the time interval of the necessary weather forecast data and suppress the increase in the cost required to acquire weather forecast data.

[0069] Figure 2 is a flowchart schematically illustrating an example of the operation of a solar power generation system according to the embodiment. As shown in Figure 2, in the photovoltaic power generation system 10, the power generation prediction model 64a is first generated (step S101 in Figure 2). The power generation prediction model 64a is generated by external equipment or the control unit 60 of the output control device 16, as described above, and then stored in the memory unit 64 of the output control device 16.

[0070] After generating the power generation prediction model 64a and storing it in the storage unit 64, the control unit 60 of the output control device 16 communicates with an external device via the communication unit 63 to acquire weather forecast data from the external device (step S102 in Figure 2). The control unit 60 acquires a day's worth of weather forecast data at once, for example, during nighttime or early morning hours, and stores the acquired weather forecast data in the storage unit 64.

[0071] After acquiring weather forecast data, the control unit 60 starts controlling the power converter 14 using feedforward control (step S103 in Figure 2).

[0072] The control unit 60 reads, for example, data (solar radiation information) for the time of the next control cycle from the weather forecast data stored in the storage unit 64 at predetermined control cycle intervals. The control unit 60 may also obtain data for the time of the next control cycle from an external device at predetermined control cycle intervals by communicating with the external device at predetermined control cycle intervals.

[0073] Furthermore, at predetermined control cycles, the control unit 60 acquires information on the amount of power required by the load 4, the amount of purchased electricity supplied to the load 4 from the power system 2, and the current amount of power generated by the solar panels 12.

[0074] After acquiring weather forecast data (data for the time of the next control cycle) and other information, the control unit 60 predicts the magnitude of the power generated by the solar panels 12 after a predetermined time (the time of the next control cycle) based on the acquired weather forecast data and the power generation prediction model 64a stored in the storage unit 64. Based on the predicted magnitude of the power generated, it controls the power conversion operation of the power converter 14 by feedforward control.

[0075] If the control unit 60 detects the occurrence of reverse power flow by the reverse power relay 26 as a result of the power conversion operation performed by the power converter 14, it stops the power conversion operation by the power converter 14 in response to the input of the reverse power flow detection signal from the reverse power relay 26 (steps S104 and S105 in Figure 2).

[0076] If the reverse power relay 26 does not detect the occurrence of reverse power flow, the control unit 60 calculates the difference between the current power generation of the solar panel 12 and the predicted power generation, and determines whether the calculated difference is greater than or equal to a predetermined value (step S106 in Figure 2).

[0077] If the control unit 60 determines that the value is less than a predetermined value, it returns to the process in step S103 and continues to control the power converter 14 using feedforward control.

[0078] On the other hand, if the control unit 60 determines that the value is above a predetermined value, it switches from controlling the power converter 14 by feedforward control to controlling the power converter 14 by feedback control based on the current amount of power generated by the solar panel 12 (step S107 in Figure 2).

[0079] If the control unit 60 detects the occurrence of reverse power flow by the reverse power relay 26 as a result of controlling the power converter 14 by feedback control, it stops the power conversion operation of the power converter 14 in response to the input of the reverse power flow detection signal from the reverse power relay 26, similar to the case of feedforward control (steps S108 and S105 in Figure 2).

[0080] If the reverse power relay 26 does not detect the occurrence of reverse power flow, the control unit 60 determines whether or not it has reached the control cycle of the feedforward control (step S109 in Figure 2). As described above, the control unit 60, for example, makes the control cycle of the feedback control shorter than the control cycle of the feedforward control. If it has not reached the control cycle of the feedforward control, the control unit 60 returns to the process in step S107 and controls the power converter 14 by feedback control at each control cycle of the feedback control.

[0081] When the control cycle of the feedforward control is reached, the control unit 60 returns to the process of step S106 and, similar to the feedforward control, reads the data (solar radiation information) for the time of the next control cycle from the weather forecast data stored in the storage unit 64. Based on the acquired weather forecast data and the power generation forecast model 64a stored in the storage unit 64, it predicts the magnitude of the power generated by the solar panels 12 after a predetermined time (the time of the next control cycle), calculates the deviation between the current power generation magnitude of the solar panels 12 and the predicted power generation magnitude, and determines whether the calculated deviation is greater than or equal to a predetermined value.

[0082] If the control unit 60 determines that the value is above a predetermined value, it continues to control the power converter 14 using feedback control. If the control unit 60 determines that the value is below the predetermined value, it returns to the process in step S103 and switches from controlling the power converter 14 using feedback control to controlling the power converter 14 using feedforward control.

[0083] As described above, in the photovoltaic power generation system 10 and output control device 16 according to this embodiment, the control unit 60 of the output control device 16 predicts the amount of power generated by the solar panels 12 after a predetermined time based on weather forecast data and power generation prediction model 64a, and controls the operation of power conversion by the power converter 14 by feedforward control based on the predicted amount of power generated.

[0084] As a result, the photovoltaic power generation system 10 and output control device 16 according to this embodiment can suppress wasted power and the shutdown of the power converter 14 due to reverse power flow, compared to the case where the power converter 14 is controlled solely by feedback control. Therefore, the photovoltaic power generation system 10 and output control device 16 according to this embodiment can suppress the occurrence of reverse power flow and make more appropriate use of the power generated by distributed power sources.

[0085] Furthermore, in the photovoltaic power generation system 10 and output control device 16 according to this embodiment, the control unit 60 switches from feedforward control of the power converter 14 to feedback control of the power converter 14 when the deviation between the current power generation amount of the photovoltaic panel 12 and the predicted power generation amount exceeds a predetermined value. This allows the control of the power converter 14 to be appropriately continued by feedback control even if the power generation prediction is significantly off.

[0086] In the above embodiment, a solar power generation system 10 is shown as an example of a distributed power system, using solar panels 12 as a distributed power source. The distributed power source is not limited to solar panels 12, but may also be, for example, a wind turbine or a geothermal generator. The distributed power source may be any power source capable of supplying the generated electricity. The electricity supplied by the distributed power source is not limited to DC power, but may also be AC ​​power, etc. The distributed power system is not limited to the solar power generation system 10, but may be any system using any distributed power source.

[0087] If the distributed power source is a wind turbine, the meteorological information in the power generation prediction model 64a and the weather forecast data includes, for example, information on wind speed and wind direction at the location where the wind turbine is installed. However, the meteorological information is not limited to the above and may be any information that allows for the prediction of the magnitude of power generated by the distributed power source based on the weather forecast at the location where the distributed power source is installed.

[0088] This embodiment includes the following aspects. (Note 1) An output control device used in a fully self-consumption type distributed power system that suppresses the purchase of electricity from the power grid to the load by converting power supplied from distributed power sources into AC power corresponding to the load using a power conversion device, and supplying the converted AC power to the load, A communication unit that receives inputs of information on the amount of power required by the load and information on the current amount of power generated by the distributed power source, A storage unit stores a power generation prediction model that enables the prediction of the amount of power generated by the distributed power source based on weather forecasts for the locations where the distributed power source is installed, by associating and storing weather information for the locations where the distributed power source is installed with the amount of power generated by the distributed power source. By communicating with external equipment via the communication unit, weather forecast data representing the weather forecast results for the location where the distributed power supply is installed is obtained from the external equipment, and a control unit controls the operation of power conversion by the power converter based on information on the amount of power required by the load, information on the current amount of power generated by the distributed power supply, the power generation forecast model, and the weather forecast data. Equipped with, The control unit predicts the magnitude of the power generated by the distributed power source after a predetermined time based on the weather forecast data and the power generation forecast model, and controls the power conversion operation of the power converter by feedforward control based on the predicted magnitude of the power generated.

[0089] (Note 2) The control unit calculates the difference between the current magnitude of power generated by the distributed power source and the predicted magnitude of power generated, based on information on the current magnitude of power generated by the distributed power source, and switches from controlling the power converter by feedforward control to controlling the power converter by feedback control based on the current magnitude of power generated by the distributed power source, as described in Appendix 1.

[0090] (Note 3) The distributed power supply system has a reverse power relay that detects reverse power flow from the power converter toward the power grid, and if the reverse power flow condition continues for a predetermined time or longer, inputs the reverse power flow detection signal to the power converter, thereby causing the power converter to stop operating. The control unit shortens the control period in the feedback control to a shorter period in the feedforward control. The output control device according to Appendix 2, wherein the control period in the feedback control is set to be shorter than the predetermined time when the reverse power relay detects the occurrence of the reverse power flow.

[0091] (Note 4) A fully self-consumption type distributed power system that converts power supplied from distributed power sources into AC power corresponding to the load using a power conversion device, and supplies the converted AC power to the load, thereby suppressing the purchase of electricity from the power grid to the load, A distributed power source that generates electricity and also supplies the electricity it generates, A power conversion device that converts 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, Equipped with, The output control device is A communication unit that receives inputs of information on the amount of power required by the load and information on the current amount of power generated by the distributed power source, A storage unit stores a power generation prediction model that enables the prediction of the amount of power generated by the distributed power source based on weather forecasts for the locations where the distributed power source is installed, by associating and storing weather information for the locations where the distributed power source is installed with the amount of power generated by the distributed power source. By communicating with external equipment via the communication unit, weather forecast data representing the weather forecast results for the location where the distributed power supply is installed is obtained from the external equipment, and a control unit controls the operation of power conversion by the power converter based on information on the amount of power required by the load, information on the current amount of power generated by the distributed power supply, the power generation forecast model, and the weather forecast data. It has, The control unit predicts the magnitude of the power generated by the distributed power source after a predetermined time based on the weather forecast data and the power generation forecast model, and controls the operation of the power conversion device by feedforward control based on the predicted magnitude of the power generated, in a distributed power system.

[0092] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0093] 2…Power system, 4…Load, 6…Transformer, 8…In-house system, 10…Solar power generation system (distributed power system), 12…Solar panels (distributed power source), 14…Power converter, 16…Output control device, 18…Monitoring device, 20…Switchboard, 22, 24…Power meter, 26…Reverse power relay, 30~33…Communication line, 35…Signal line, 50…Conversion circuit, 51…Control unit, 52, 53…Communication unit, 54…Input unit, 60…Control unit, 61~63…Communication unit, 64…Storage unit, 64a…Power generation prediction model

Claims

1. An output control device used in a fully self-consumption type distributed power system that suppresses the purchase of electricity from the power grid to the load by converting power supplied from distributed power sources into AC power corresponding to the load using a power conversion device, and supplying the converted AC power to the load, A communication unit that receives inputs of information on the amount of power required by the load and information on the current amount of power generated by the distributed power source, A storage unit stores a power generation prediction model that enables the prediction of the amount of power generated by the distributed power source based on weather forecasts for the locations where the distributed power source is installed, by associating and storing weather information for the locations where the distributed power source is installed with the amount of power generated by the distributed power source. By communicating with external equipment via the communication unit, weather forecast data representing the weather forecast results for the location where the distributed power supply is installed is obtained from the external equipment, and a control unit controls the operation of power conversion by the power converter based on information on the amount of power required by the load, information on the current amount of power generated by the distributed power supply, the power generation forecast model, and the weather forecast data. Equipped with, The control unit predicts the magnitude of the power generated by the distributed power source after a predetermined time based on the weather forecast data and the power generation forecast model, and controls the power conversion operation of the power converter by feedforward control based on the predicted magnitude of the power generated.

2. The output control device according to claim 1, wherein the control unit calculates the difference between the current magnitude of power generated by the distributed power source and the predicted magnitude of power generated, based on information on the current magnitude of power generated by the distributed power source, and switches from controlling the power converter by feedforward control to controlling the power converter by feedback control based on the current magnitude of power generated by the distributed power source if the difference is greater than or equal to a predetermined value.

3. The distributed power supply system has a reverse power relay that detects reverse power flow from the power converter toward the power grid, and if the reverse power flow condition continues for a predetermined time or longer, inputs the reverse power flow detection signal to the power converter, thereby causing the power converter to stop operating. The control unit shortens the control period in the feedback control to a shorter period in the feedforward control. The output control device according to claim 2, wherein the control period in the feedback control is set to be shorter than the predetermined time when the reverse power relay detects the occurrence of the reverse power flow.

4. A fully self-consumption type distributed power system that converts power supplied from distributed power sources into AC power corresponding to the load using a power conversion device, and supplies the converted AC power to the load, thereby suppressing the purchase of electricity from the power grid to the load, A distributed power source that generates electricity and also supplies the electricity it generates, A power conversion device that converts 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, Equipped with, The output control device is A communication unit that receives inputs of information on the amount of power required by the load and information on the current amount of power generated by the distributed power source, A storage unit stores a power generation prediction model that enables the prediction of the amount of power generated by the distributed power source based on weather forecasts for the locations where the distributed power source is installed, by associating and storing weather information for the locations where the distributed power source is installed with the amount of power generated by the distributed power source. By communicating with external equipment via the communication unit, weather forecast data representing the weather forecast results for the location where the distributed power supply is installed is obtained from the external equipment, and a control unit controls the operation of power conversion by the power converter based on information on the amount of power required by the load, information on the current amount of power generated by the distributed power supply, the power generation forecast model, and the weather forecast data. It has, The control unit predicts the magnitude of the power generated by the distributed power source after a predetermined time based on the weather forecast data and the power generation forecast model, and controls the operation of the power conversion device by feedforward control based on the predicted magnitude of the power generated, in a distributed power system.

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