Electric power conversion system

Abstract

To provide a power conversion device capable of prioritizing the output power of a second distributed power source over the output power of a first distributed power source even without a step-down circuit.SOLUTION: A power conversion device includes a first DC / DC converter connected to a first distributed power source, a second DC / DC converter connected to a second distributed power source, and an inverter connected to the first DC / DC converter and the second DC / DC converter via a DC link unit. The first DC / DC converter includes a first input terminal connected to a first pole of the first distributed power source, a second input terminal connected to a second pole of the first distributed power source, and a switch unit installed on a wiring electrically connecting the first input terminal and the second input terminal. When priority output control is executed in which the output power of the second distributed power source is prioritized over the output power of the first distributed power source, the switch unit is controlled to a connection state in which the first input terminal and the second input terminal are electrically connected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a power conversion device. [Background technology]

[0002] Conventionally, a power conditioner is known that includes a first DC / DC converter connected to a first distributed power source (e.g., a solar cell device), a second DC / DC converter connected to a second distributed power source (e.g., a power storage device), and an inverter connected to the first DC / DC converter and the second DC / DC converter. Assuming a case where the power storage device is charged by the output power of the solar cell device, a structure is known as such a power conditioner that shorts both poles of the solar cell device when the power storage device is disconnected (e.g., Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-121455 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, assuming the above-mentioned power conditioner, a case may be assumed in which the first distributed power source and the second distributed power source are used in a VPP (Virtual Power Plant).In such a case, when both the first distributed power source and the second distributed power source are capable of outputting power, there may be a need to prioritize the output power of the second distributed power source over the output power of the first distributed power source.

[0005] For example, if a first DC / DC converter connected to a first distributed power source has a step-down circuit, it is possible to prioritize the output power of the second distributed power source over the output power of the first distributed power source by lowering the output voltage of the first DC / DC converter below the output voltage of the second DC / DC converter.

[0006] However, from the standpoint of cost or reduction in circuit scale, if the first DC / DC converter does not have a step-down circuit, it is not possible to prioritize the output power of the second distributed power source over the output power of the first distributed power source.

[0007] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a power conversion device that makes it possible to prioritize the output power of a second distributed power source over the output power of a first distributed power source, even without having a step-down circuit. [Means for solving the problem]

[0008] An aspect of the disclosure is a power conversion device comprising: a first DC / DC converter connected to a first distributed power source; a second DC / DC converter connected to a second distributed power source; an inverter connected to the first DC / DC converter and the second DC / DC converter via a DC link unit; and the first DC / DC converter comprises a first input terminal connected to a first pole of the first distributed power source, a second input terminal connected to a second pole of the first distributed power source, and a switch unit installed on wiring electrically connecting the first input terminal and the second input terminal, wherein the switch unit is controlled to a connection state in which the first input terminal and the second input terminal are electrically connected when priority output control is executed in which the output power of the second distributed power source is given priority over the output power of the first distributed power source. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a power conversion device that is capable of prioritizing the output power of a second distributed power source over the output power of a first distributed power source even without a step-down circuit. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a power conversion system 1 according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing a DC / DC 110A according to an embodiment. [Diagram 3] FIG. 3 is a diagram showing a non-connected state according to the embodiment. [Figure 4] FIG. 4 is a diagram showing a connection state according to the embodiment. [Diagram 5] FIG. 5 is a diagram showing a DC / DC 110A according to the first modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic.

[0012] [Embodiment] (Power Conversion System) A power conversion system according to an embodiment will be described below.

[0013] 1, the power conversion system 1 includes a power conditioning system (PCS) 100. The power conversion system 1 may include a PV 10A and a BT 10B as distributed power sources 10. In the embodiment, the PCS 100 is an example of a power conversion device.

[0014] The PCS 100 includes a DC / DC 110 (DC / DC 110A and DC / DC 110B), an INV 120, a relay 130, a capacitor 140, and a control device 150. The PCS 100 may include a grid-connected output 161 and an independent output 162. The PCS 100 may include a switch unit 181.

[0015] The DC / DC 110A is a DC / DC converter connected to the PV 10A. In the embodiment, the PV 10A is an example of a first distributed power source, and the DC / DC 110A is an example of a first DC / DC converter. For example, the PV 10A is a solar panel that outputs power in response to received light. The DC / DC 110A converts the voltage of the output power of the PV 10A. For example, the DC / DC 110A boosts the voltage of the output power of the PV 10A.

[0016] The DC / DC 110B is a DC / DC converter connected to the BT10B. In the embodiment, the BT10B is an example of a second distributed power source, and the DC / DC 110B is an example of a second DC / DC converter. For example, the BT10B is a power storage cell that stores power. The DC / DC 110B converts the voltage of the output power of the BT10B. For example, the DC / DC 110B boosts the voltage of the output power of the BT10B. Or, the DC / DC 110B lowers the voltage of the output power of the INV120.

[0017] The INV 120 is an inverter connected to the DC / DC 110A and the DC / DC 110B via a DC link unit 171. In the embodiment, the DC link unit 171 is an example of a DC link unit that is a path of DC power in the PCS 100. The INV 120 is an example of an inverter. The DC link unit may be referred to as an intermediate link unit.

[0018] The INV 120 converts the direct current power (hereinafter, DC power) output from the DC / DC 110A into alternating current power (hereinafter, AC power). The INV 120 converts the DC power output from the DC / DC 110B into AC power. The INV 120 converts the AC power input from the power grid into DC power.

[0019] The relay 130 switches the output to which the INV 120 is connected between the grid-connected output 161 and the isolated output 162. That is, when the operating state of the PCS 100 is the grid-connected state, the relay 130 connects the INV 120 to the grid-connected output 161, and when the operating state of the PCS 100 is the isolated state, the relay 130 connects the INV 120 to the isolated output 162. The grid-connected state is a state in which the PCS 100 is connected to the power grid, and the isolated state is a state in which the PCS 100 is disconnected from the power grid.

[0020] The capacitor 140 is a capacitor connected to the DC link unit 171. For example, the capacitor 140 may be used to smooth the DC power output from the DC / DC 110A and the DC / DC 110B. The capacitor 140 may be referred to as a capacitor.

[0021] The control device 150 controls the PCS 100. The control device 150 may have a communication module. The communication module may be an example of a first communication unit that communicates with the PCS 100. The communication module may be a wireless communication module that complies with standards such as IEEE802.11a / b / g / n, ZigBee, Wi-SUN, LTE, and 5G, or may be a wired communication module that complies with standards such as IEEE802.3 and RS485.

[0022] For example, the control device 150 may be connected to the DC / DC 110A by a signal line. The control device 150 may be connected to the DC / DC 110B by a signal line. The control device 150 may be connected to the INV 120 by a signal line. These signal lines may include wired signal lines or wireless signal lines.

[0023] The control device 150 may include at least one processor. The at least one processor may be configured by a single integrated circuit (IC) or may be configured by multiple circuits (such as integrated circuits and / or discrete circuits) communicatively connected to each other.

[0024] The grid-connected output 161 is an input / output terminal used when the operating state of the PCS 100 is a grid-connected state. The grid-connected output 161 is connected to the power system (U phase and W phase). For example, the voltage of the grid-connected output 161 may be 202V.

[0025] The independent output 162 is an output terminal used when the operating state of the PCS 100 is an independent state. For example, the voltage of the independent output 162 may be 202V or 101V. For example, the independent output 162 may be connected to a load device (e.g., an air conditioner, an IH cooking heater, a washer-dryer, etc.) that operates at 202V without being connected to a power grid. The independent output 162 is connected to a load device (e.g., a mobile phone, a personal computer, etc.) that operates at 101V without being connected to a power grid.

[0026] The switch unit 181 is installed on a power line that electrically connects the BT 10B and the DC / DC 110B. The switch unit 181 switches whether or not the BT 10B is electrically connected to the PCS 100.

[0027] (First DC / DC converter) The first DC / DC converter (DC / DC 110A) according to an embodiment will be described below.

[0028] As shown in FIG. 2, the DC / DC 110A has a first input terminal 111A, a second input terminal 111B, a first output terminal 112A, a second output terminal 112B, a wiring 113A, a wiring 113B, a wiring 114, and a switch unit 115.

[0029] The first input terminal 111A is an input terminal that is connected to the first pole (positive pole) of the PV 10A.

[0030] The second input terminal 111B is an input terminal that is connected to the second pole (negative pole) of the PV 10A.

[0031] The first output terminal 112A is an output terminal that is connected to the first pole (positive pole) of the INV120.

[0032] The second output terminal 112B is an output terminal that is connected to the second pole (negative pole) of the INV120.

[0033] The wiring 113A is a wiring that electrically connects the first input terminal 111A and the first output terminal 112A. A reactor and a diode may be installed on the wiring 113A.

[0034] The wiring 113B is a wiring that electrically connects the second input terminal 111B and the second output terminal 112B. A resistor may be provided on the wiring 113B.

[0035] The wiring 114 is a wiring for electrically connecting the wiring 113A and the wiring 113B. That is, the wiring 114 is a wiring for electrically connecting the first input terminal 111A and the second input terminal 111B.

[0036] The switch section 115 is disposed on the wiring 114 for electrically connecting the first input terminal 111A and the second input terminal 111B.

[0037] For example, the switch unit 115 may be controlled to a disconnected state in which the first input terminal 111A and the second input terminal 111B are electrically disconnected. As shown in FIG. 3, when the switch unit 115 is in a disconnected state, the DC / DC 110A boosts the voltage of the output power of the PV 10A and outputs the boosted power to the INV 120.

[0038] For example, the switch unit 115 may be controlled to a connection state in which the first input terminal 111A and the second input terminal 111B are electrically connected. As shown in Fig. 4, when the switch unit 115 is in a connection state, the first input terminal 111A and the second input terminal 111B are short-circuited, and the voltage of the output power of the PV 10A drops to about several volts.

[0039] The non-connected state and connected state of the switch unit 115 may be controlled by a control command from the control device 150.

[0040] (assignment) Problems associated with the embodiment will be described below.

[0041] In the above-mentioned PCS100, since the output power of the PV10A can be stepped down by the DC / DC 110B and charged to the BT10B, from the viewpoint of effectively utilizing the output power of the PV10A, the DC / DC 110A does not need to step down the voltage of the output power of the PV10A. Therefore, the DC / DC 110A does not generally have a step-down circuit that steps down the voltage of the output power of the PV10A. Furthermore, if a step-down circuit is arranged in the DC / DC 110A, not only will the circuit size and cost of the DC / DC 110A increase, but when charging the BT10B, the conversion loss will increase due to the double step-down control performed by both the DC / DC 110A and the DC / DC 110B. For these reasons, a step-down circuit is generally not required in the DC / DC 110A.

[0042] On the other hand, in a VPP (Virtual Power Plant) or the like, from the viewpoint of stabilizing the balance of supply and demand in the power system, there is a need to reduce the remaining amount of stored electricity in BT10B, and there may be cases where control that prioritizes the output power of BT10B over the output power of PV10A (hereinafter, priority output control) is required. For example, a case where there is a need to reduce the remaining amount of stored electricity in BT10B may be a case where a command to increase the demand for electricity (for example, an increase DR (Demand Response)) is issued when it is expected that the power supply in the power system will be excessive at a future time.

[0043] However, since the DC / DC 110A generally does not have a step-down circuit, it is not possible to appropriately execute the above-mentioned priority output control.

[0044] In consideration of such a problem, in the embodiment, the following operation example may be executed.

[0045] (Example of operation) An operation example according to the embodiment will be described below. As the operation example, the following operation example is considered.

[0046] In the first operation example, when a first specific condition is satisfied, the switch unit 115 is controlled to a connected state in which the first input terminal 111A and the second input terminal 111B are electrically connected. In other words, when a first specific condition is satisfied, the control device 150 controls the switch unit 115 to a connected state. As the first specific condition, the following options are considered.

[0047] In option 1-1, the first specific condition may include a condition for executing priority output control that prioritizes the output power of the BT 10B over the output power of the PV 10A. Whether or not to execute priority output control may be determined by the control device 150. Whether or not to execute priority output control may be determined by an EMS (Energy Management System) installed in a facility having the PCS 100. Whether or not to execute priority output control may be determined by a higher-level node (e.g., an Aggregator) that manages the power of the power system.

[0048] In this way, in option 1-1, the control device 150 may control the switch unit 115 to the connected state when the priority output control is executed. The switch unit 115 may be controlled to the connected state when the priority output control is executed.

[0049] In option 1-2, the first specific condition may include a condition that the voltage of the DC link unit 171 is equal to or greater than the first threshold. The first threshold may be equal to or greater than the maximum output voltage of BT10B (for example, 390V). In other words, in option 1-2, assuming a case in which the maximum output voltage of PV10A (for example, 450V) is higher than the maximum output voltage of BT10B (for example, 390V), the occurrence of a situation in which the output voltage of PV10A is higher than the output voltage of BT10B and the output power of BT10B is not prioritized is suppressed. Also, in a case in which the output voltage of PV10A is lower than the output voltage of BT10B, the occurrence of a situation in which the use of the output power of PV10A is hindered is suppressed. The output voltage of PV10A may be read as the output voltage of DC / DC 110A. The output voltage of BT10B may be read as the output voltage of DC / DC 110B. When interpreted as the output voltage of the DC / DC 110, the control device 150 may be connected to the DC / DC 110 via a signal line and acquire voltage information of the DC / DC 110.

[0050] Thus, in option 1-2, the control device 150 may control the switch unit 115 to the connected state when the voltage of the DC link unit 171 is equal to or higher than the first threshold. The switch unit 115 may be controlled to the connected state when the voltage of the DC link unit 171 is equal to or higher than the first threshold.

[0051] In option 1-3, the first specific condition may include a condition that the input voltage to the DC / DC 110A is equal to or greater than the second threshold. The second threshold may be equal to or greater than the maximum output voltage of the BT10B (e.g., 390V). The second threshold may be the same as the first threshold, or may be different from the first threshold. In other words, in option 1-3, assuming a case in which the maximum output voltage of the PV10A (e.g., 450V) is higher than the maximum output voltage of the BT10B (e.g., 390V), the output voltage of the PV10A is higher than the output voltage of the BT10B, and the output power of the BT10B is prevented from being prioritized. In addition, in a case in which the output voltage of the PV10A is lower than the output voltage of the BT10B, the use of the output power of the PV10A is prevented from being hindered.

[0052] Thus, in options 1-3, the control device 150 may control the switch unit 115 to the connected state when the input voltage to the DC / DC 110A is equal to or greater than the second threshold. The switch unit 115 may be controlled to the connected state when the input voltage to the DC / DC 110A is equal to or greater than the second threshold.

[0053] In option 1-4, the first specific condition may include a condition that the predicted value of the input voltage to the DC / DC 110A is equal to or greater than a third threshold. The third threshold may be equal to or greater than the maximum output voltage (e.g., 390V) of the BT 10B. The third threshold may be the same as the first threshold or the second threshold, or may be different from the first threshold and the second threshold. The predicted value of the input voltage to the DC / DC 110A may be predicted based on the temperature related to the PV 10A. The temperature related to the PV 10A may be the temperature of the PV panel of the PV 10A or the temperature of the photovoltaic cell of the PV 10A. The temperature related to the PV 10A may be the temperature of the surroundings of the PV panel or the photovoltaic cell. These temperatures may be detected by a sensor installed on the PV 10A or in the vicinity of the PV 10A, and the predicted value may be calculated based on temperature forecast data provided by the Japan Meteorological Agency or the like. The temperature forecast data may be data for each hour of the area in which the PV 10A is installed. For example, when the temperature related to the PV 10A increases, the input voltage to the DC / DC 110A may be predicted to increase, and when the temperature related to the PV 10A decreases, the input voltage to the DC / DC 110A may be predicted to decrease. In the options 1-4, the occurrence of a situation in which the output power of the BT 10B is not prioritized at a future time is suppressed in advance.

[0054] Thus, in options 1-4, the control device 150 may control the switch unit 115 to the connected state when the predicted value of the input voltage to the DC / DC 110A is equal to or greater than the third threshold. The switch unit 115 may be controlled to the connected state when the predicted value of the input voltage to the DC / DC 110A is equal to or greater than the third threshold.

[0055] In the operation example 1, when a first specific condition of any one of options 1-1 to 1-4 is satisfied, the switch unit 115 may be controlled to a connection state in which the first input terminal 111A and the second input terminal 111B are electrically connected. Furthermore, in the operation example 1, when a first specific condition of a combination of two or more options selected from options 1-1 to 1-4 is satisfied, the switch unit 115 may be controlled to a connection state in which the first input terminal 111A and the second input terminal 111B are electrically connected.

[0056] In the second operation example, when a second specific condition is satisfied, the switch unit 115 is controlled to a non-connected state in which the first input terminal 111A and the second input terminal 111B are electrically disconnected. In other words, when a second specific condition is satisfied, the control device 150 controls the switch unit 115 to a non-connected state. The following options are possible as the second specific condition.

[0057] In option 2-1, the second specific condition may include a condition for canceling the priority output control that prioritizes the output power of the BT 10B over the output power of the PV 10A. Whether or not to cancel the priority output control may be determined by the control device 150. Whether or not to cancel the priority output control may be determined to be executed by an EMS installed in a facility having the PCS 100. Whether or not to cancel the priority output control may be determined by an upper node (e.g., an Aggregator) that manages the power of the power system.

[0058] In this way, in option 2-1, the control device 150 may control the switch unit 115 to a non-connected state when the priority output control is released. The switch unit 115 may be controlled to a non-connected state when the priority output control is released.

[0059] In option 2-2, the second specific condition may include a condition that the voltage of the DC link unit 171 falls below a first threshold. The first threshold may be a value equal to or greater than the maximum output voltage of the BT10B (for example, 390V).

[0060] In this way, in option 2-2, the control device 150 may control the switch unit 115 to a non-connected state when the voltage of the DC link unit 171 falls below the first threshold. The switch unit 115 may be controlled to a non-connected state when the voltage of the DC link unit 171 falls below the first threshold. Option 2-2 may be based on the above-mentioned option 1-2.

[0061] In option 2-2, the first threshold value may be interpreted as the maximum output voltage of BT10B (e.g., 390V). In other words, the control device 150 may control the switch unit 115 to maintain the connection state until the voltage of the DC link unit 171 falls below the maximum output voltage of BT10B. The switch unit 115 may be controlled to maintain the connection state until the voltage of the DC link unit 171 falls below the maximum output voltage of BT10B.

[0062] In option 2-3, the second specific condition may include a condition that the temperature related to PV 10A is equal to or lower than a fourth threshold. The fourth threshold may be a value that assumes that the output voltage of PV 10A is lower than the output voltage of BT 10B. Option 2-2 may be premised on option 1-4 described above.

[0063] Thus, in option 2-3, the control device 150 may control the switch unit 115 to the non-connected state when the temperature related to the PV 10A is equal to or lower than the fourth threshold. The switch unit 115 may be controlled to the non-connected state when the temperature related to the PV 10A is equal to or lower than the fourth threshold.

[0064] In option 2-4, the second specific condition may include a condition that the remaining amount of stored power of the BT10B reaches a target remaining amount. The target remaining amount may be set by the control device 150. The target remaining amount may be set by an EMS installed in a facility having the PCS 100. The target remaining amount may be set by a higher-level node (e.g., an aggregator) that manages the power of the power system.

[0065] In this way, in option 2-4, the control device 150 may control the switch unit 115 to the non-connected state when the remaining amount of stored power of BT10B reaches the target remaining amount. The switch unit 115 may be controlled to the non-connected state when the remaining amount of stored power of BT10B reaches the target remaining amount.

[0066] In option 2-5, the switch unit 115 may be controlled by a specific operation that alternates between a connected state and a non-connected state. The specific operation may be a repetition of an operation in which the connected state continues for a first time and the non-connected state continues for a second time. The first time may be the same as the second time or may be different from the second time.

[0067] Under such a premise, the second specific condition may include a condition that the input voltage to the DC / DC 110A does not exceed a fifth threshold. The fifth threshold may be a value equal to or lower than the maximum output voltage of the BT 10B (e.g., 390V). The fifth threshold may be the same as the second threshold described in Option 1-3, or may be a value lower than the second threshold.

[0068] Thus, in option 2-5, the control device 150 may control the switch unit 115 by a specific operation that alternates between a connected state and a non-connected state. The switch unit 115 may be controlled by a specific operation that alternates between a connected state and a non-connected state.

[0069] In the operation example 2, when the second specific condition of any one of the options 2-1 to 2-5 is satisfied, the switch unit 115 may be controlled to a non-connected state in which the first input terminal 111A and the second input terminal 111B are electrically disconnected. Furthermore, in the operation example 2, when the second specific condition of a combination of two or more options selected from the options 2-1 to 2-5 is satisfied, the switch unit 115 may be controlled to a non-connected state in which the first input terminal 111A and the second input terminal 111B are electrically disconnected.

[0070] (Action and Effects) In the embodiment, the switch unit 115 may be controlled to a connected state when the priority output control is executed (option 1-1). With such a configuration, even if the DC / DC 110A does not have a step-down circuit, the output power of the BT 10B can be appropriately prioritized over the output power of the PV 10A.

[0071] In the embodiment, the switch unit 115 may be controlled to the connected state when the voltage of the DC link unit 171 is equal to or higher than the first threshold (option 1-2). With such a configuration, it is possible to prevent the occurrence of a situation in which the output power of the BT 10B is not given priority in the priority output control. Also, when the voltage of the DC link unit 171 is lower than the first threshold, it is possible to prevent the occurrence of a situation in which the use of the output power of the PV 10A is hindered.

[0072] In the embodiment, the switch unit 115 may be controlled to a connected state when the input voltage to the DC / DC 110A is equal to or higher than the second threshold (option 1-3). With such a configuration, it is possible to prevent the occurrence of a situation in which the output power of the BT 10B is not given priority in the priority output control. Also, when the input voltage to the DC / DC 110A is lower than the second threshold, it is possible to prevent the occurrence of a situation in which the use of the output power of the PV 10A is hindered.

[0073] In the embodiment, the switch unit 115 may be controlled to the connected state when the predicted value of the input voltage to the DC / DC 110A is equal to or greater than the third threshold (option 1-4). With this configuration, it is possible to prevent in advance the occurrence of a situation in which the output power of the BT 10B is not prioritized at a future time.

[0074] In the embodiment, the switch unit 115 may be controlled to the non-connected state when the second specific condition is satisfied (Option 2-1 to Option 2-5). With such a configuration, it is possible to prevent the occurrence of a situation in which the output power of the PV 10A is not effectively utilized due to the unnecessarily continuing connected state.

[0075] [Change Example 1] Modification 1 of the embodiment will be described below. Differences from the embodiment will be mainly described below.

[0076] 5, the PCS 100 may have two or more DC / DCs 110A (DC / DCs 110A1 and 110A2) connected to two or more PVs 10A (PVs 10A1 and 10A2), respectively. The DC / DCs 110A1 and 110A2 may have the same configuration as the DC / DC 110A described above.

[0077] In the first modification, the control device 150 may determine whether or not the above-mentioned first specific condition is satisfied for each of two or more DC / DCs 110A (DC / DC 110A1 and DC / DC 110A2). The control device 150 may control the switch unit 115 of the DC / DC 110A for which the first specific condition is satisfied to the connected state. The switch unit 115 of the DC / DC 110A for which the first specific condition is satisfied may be controlled to the connected state.

[0078] In the first modification, the control device 150 may determine whether or not the above-mentioned second specific condition is satisfied for each of the two or more DC / DCs 110A (DC / DC 110A1 and DC / DC 110A2). The control device 150 may control the switch unit 115 of the DC / DC 110A for which the second specific condition is satisfied to a non-connected state. The DC / DC 110A for which the second specific condition is satisfied may be controlled to a non-connected state.

[0079] [Change Example 2] Modification 2 of the embodiment will be described below. Differences from the embodiment will be mainly described below.

[0080] In the second modification, a case in which both the first and second specific conditions are satisfied will be described.

[0081] First, a case will be described in which a second specific condition is satisfied after a first specific condition is satisfied. In such a case, the following options are considered:

[0082] In option 3-1, the control device 150 may control the switch unit 115 of the DC / DC 110 to a connected state when a first specific condition is satisfied, and may control the switch unit 115 of the DC / DC 110 to a disconnected state when a second specific condition is satisfied. That is, the switch unit 115 of the DC / DC 110 may be controlled according to the condition that is satisfied later in time.

[0083] In option 3-2, the control device 150 may control the switch unit 115 of the DC / DC 110 to the connected state when a first specific condition A (e.g., a condition under which priority output control of option 1-1 is executed) is satisfied, maintain the switch unit 115 of the DC / DC 110 in the connected state even when a second specific condition B (e.g., an option other than option 2-1) is satisfied, and control the switch unit 115 of the DC / DC 110 to the non-connected state when a second specific condition C other than the second specific condition B is satisfied. In other words, the first specific condition A may always take precedence over the second specific condition B.

[0084] Here, at least one of the correspondence relationship between the first specific condition A and the second specific condition B and the correspondence relationship between the first specific condition A and the second specific condition C may be determined in advance. Each of the first specific condition A, the second specific condition B, and the second specific condition C may be one option (condition) or may include two or more options (conditions).

[0085] Secondly, a case where the first specific condition is satisfied after the second specific condition is satisfied will be described. In such a case, the following options are considered:

[0086] In option 3-3, the control device 150 may control the switch unit 115 of the DC / DC 110 to the disconnected state when the second specific condition is satisfied, and may control the switch unit 115 of the DC / DC 110 to the connected state when the first specific condition is satisfied. That is, the switch unit 115 of the DC / DC 110 may be controlled according to the condition that is satisfied later in time.

[0087] In option 3-4, when a second specific condition D (e.g., an option other than option 2-1) is satisfied, the control device 150 may control the switch unit 115 of DC / DC 110 to the disconnected state, and even when a first specific condition E (e.g., an option other than option 1-1) is satisfied, the control device 150 may maintain the switch unit 115 of DC / DC 110 in the disconnected state, and when a first specific condition F other than the first specific condition E (e.g., a condition for executing priority output control of option 1-1) is satisfied, the control device 150 may control the switch unit 115 of DC / DC 110 to the connected state.

[0088] Here, at least one of the correspondence relationship between the second specific condition D and the first specific condition E and the correspondence relationship between the second specific condition D and the first specific condition F may be determined in advance. Each of the second specific condition D, the first specific condition E, and the first specific condition F may be one option (condition) or may include two or more options (conditions).

[0089] [Other embodiments] Although the present invention has been described by the above-mentioned embodiment, the description and drawings forming a part of this disclosure should not be understood as limiting the present invention. From this disclosure, various alternative embodiments, examples and operating techniques will become apparent to those skilled in the art.

[0090] In the above disclosure, the control device 150 that controls the switch unit 115 of the DC / DC 110A is illustrated as being installed in the PCS 100. However, the above disclosure is not limited to this. The control device 150 may be installed outside the PCS 100, for example, the control device 150 may be an EMS installed in a facility having the PCS 100. The control device 150 may be an upper node (e.g., an Aggregator) that manages the power of the power system.

[0091] In the above disclosure, the case where the first distributed power source is a PV 10A has been exemplified. However, the above disclosure is not limited to this. The first distributed power source may be a distributed power source other than a solar cell device. The distributed power source other than a solar cell device may be a power generation device that utilizes natural energy (such as a wind power generation device, a hydroelectric power generation device, or a geothermal power generation device). The distributed power source other than a solar cell device may be a fuel cell device, a diesel generator, or the like.

[0092] Although not specifically mentioned in the above disclosure, the voltage of the DC link unit 171 may be referred to as an intermediate link voltage or as a bus voltage.

[0093] [Note] The above disclosure may be expressed as follows:

[0094] A first feature of the power conversion device is that it includes a first DC / DC converter connected to a first distributed power source, a second DC / DC converter connected to a second distributed power source, and an inverter connected to the first DC / DC converter and the second DC / DC converter via a DC link unit, and the first DC / DC converter includes a first input terminal connected to a first pole of the first distributed power source, a second input terminal connected to a second pole of the first distributed power source, and a switch unit installed on wiring for electrically connecting the first input terminal and the second input terminal, and the switch unit is controlled to a connection state in which the first input terminal and the second input terminal are electrically connected when priority output control is executed in which the output power of the second distributed power source is prioritized over the output power of the first distributed power source.

[0095] A second feature is the power conversion device according to the first feature, wherein the switch unit is controlled to the connected state when a voltage of the DC link unit is equal to or higher than a first threshold value.

[0096] A third feature is the power conversion device according to the first or second feature, wherein the switch unit is controlled to the connected state when an input voltage to the first DC / DC converter is equal to or higher than a second threshold.

[0097] A fourth feature is a power conversion device according to at least one of the first to third features, wherein the switch unit is controlled to maintain the connected state until a voltage of the DC link unit becomes equal to or lower than a maximum output voltage of the second distributed power source.

[0098] A fifth feature is a power conversion device according to at least one of the first feature to the fourth feature, wherein the first DC / DC converter includes two or more first DC / DC converters connected to two or more first distributed power sources, respectively, and the switch unit included in each of the two or more first DC / DC converters is controlled to the connected state when the output power of the second distributed power source is prioritized over the output power of the two or more first distributed power sources.

[0099] A sixth feature is a power conversion device in which, in at least one of the first to fifth features, the switch unit is controlled to the connected state when a predicted value of an input voltage to the first DC / DC converter is equal to or greater than a third threshold value.

[0100] A seventh feature is a power conversion device according to at least one of the first to sixth features, wherein the switch unit is controlled to a non-connected state in which the first input terminal and the second input terminal are electrically disconnected when a temperature related to the first distributed power source becomes equal to or lower than a fourth threshold value.

[0101] An eighth feature is a power conversion device according to at least one of the first to seventh features, wherein the switch unit is controlled to a non-connected state in which the first input terminal and the second input terminal are electrically disconnected when the priority output control is released.

[0102] A ninth feature is a power conversion device in which, in at least one of the first feature to the eighth feature, the second distributed power source is a power storage device, and the switch unit is controlled to a non-connected state in which the first input terminal and the second input terminal are electrically disconnected when the remaining amount of stored power of the power storage device reaches a target remaining amount.

[0103] A tenth feature is a power conversion device according to at least one of the first to ninth features, wherein the switch unit is controlled by a specific operation that alternates between the connected state and a non-connected state in which the first input terminal and the second input terminal are electrically disconnected, and when an input voltage to the first DC / DC converter does not exceed a fifth threshold during the specific operation, the switch unit is controlled to the non-connected state. [Explanation of symbols]

[0104] 1...power conversion system, 10A...PV, 10B...BT, 100...PCS, 110A...DC / DC, 110B...DC / DC, 111A...first input terminal, 111B...second input terminal, 112A...first output terminal, 112B...second output terminal, 113A...wiring, 113B...wiring, 114...wiring, 115...switch section, 120...INV, 130...relay, 140...capacitor, 150...control device, 161...grid-connected output, 162...isolated output, 171...DC link section, 181...switch section

Claims

1. a first DC / DC converter connected to a first distributed power source; a second DC / DC converter connected to the second distributed power source; an inverter connected to the first DC / DC converter and the second DC / DC converter via a DC link unit; the first DC / DC converter comprises a first input terminal connected to a first pole of the first distributed power source, a second input terminal connected to a second pole of the first distributed power source, and a switch unit installed on a wiring that electrically connects the first input terminal and the second input terminal; The switch unit is a power conversion device that is controlled to a connection state in which the first input terminal and the second input terminal are electrically connected when priority output control is executed in which the output power of the second distributed power source is given priority over the output power of the first distributed power source.

2. The power conversion device according to claim 1 , wherein the switch unit is controlled to the connected state when a voltage of the DC link unit is equal to or higher than a first threshold value.

3. 2 . The power conversion device according to claim 1 , wherein the switch unit is controlled to the connected state when an input voltage to the first DC / DC converter is equal to or higher than a second threshold value.

4. 2 . The power conversion device according to claim 1 , wherein the switch unit is controlled to maintain the connected state until a voltage of the DC link unit becomes equal to or lower than a maximum output voltage of the second distributed power source.

5. the first DC / DC converter includes two or more first DC / DC converters connected to two or more first distributed power sources, respectively; 2. The power conversion device according to claim 1, wherein the switch unit of each of the two or more first DC / DC converters is controlled to the connected state when the output power of the second distributed power source is prioritized over the output power of the two or more first distributed power sources.

6. 2 . The power conversion device according to claim 1 , wherein the switch unit is controlled to the connected state when a predicted value of an input voltage to the first DC / DC converter is equal to or greater than a third threshold value.

7. 2. The power conversion device according to claim 1, wherein the switch unit is controlled to a non-connected state in which the first input terminal and the second input terminal are electrically disconnected when a temperature related to the first distributed power source becomes equal to or lower than a fourth threshold value.

8. 2 . The power conversion device according to claim 1 , wherein the switch unit is controlled to a non-connected state in which the first input terminal and the second input terminal are electrically disconnected when the priority output control is released.

9. the second distributed power source is a power storage device; 2. The power conversion device according to claim 1, wherein the switch unit is controlled to a non-connected state in which the first input terminal and the second input terminal are electrically disconnected from each other when a remaining amount of stored power of the power storage device reaches a target remaining amount.

10. The switch unit is is controlled by a specific operation of alternately switching between the connected state and a non-connected state in which the first input terminal and the second input terminal are electrically disconnected, The power conversion device according to claim 1 , wherein the power conversion device is controlled to the non-connected state when an input voltage to the first DC / DC converter does not exceed a fifth threshold in the specific operation.

Images