Power supply equipment

Abstract

To provide a power supply facility in which each DC apparatus inside the power supply facility stably supplies DC power.SOLUTION: According to a power supply facility, the power supply facility comprises a first conversion device for performing power conversion, that is arranged between an AC power line and a DC power line; a second conversion device for performing power conversion, that is arranged between the DC power line and a storage battery; and a third conversion device for performing power conversion, that is arranged between the DC power line and a renewable energy power supply. The first conversion device controls a voltage of the DC power line to a first voltage. The second conversion device controls a voltage of the DC power line to a second voltage when the first conversion device cannot control a voltage of the DC power line to the first voltage, and the voltage of the DC power line exceeds the second voltage at which the voltage of the DC power line is set higher than the first voltage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply facility that stably supplies power generated by a renewable energy power generation device to a load. [Background technology]

[0002] Patent Document 1 is known as a power supply facility that stably supplies power generated by a renewable energy power generation device to a load. Patent Document 1 describes a power control device including a control unit configured to be able to control a bidirectional inverter connected between an AC side and a DC side, the control unit acquiring predicted values ​​for the amount of power generated by the renewable energy power generation device and the amount of power consumed by the load at a plurality of times between a first time and a second time, assuming a target charge amount for the power storage device at the second time, and updating the target charge amount at each time by applying the predicted values ​​at each time going back from the second time to the assumed target charge amount, the power control device, power control method, bidirectional inverter, and power control system causing the bidirectional inverter to perform a charging operation or a discharging operation based on the target charge amount at the first time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-52488 Summary of the Invention [Problem to be solved by the invention]

[0004] According to Patent Document 1, the storage battery can be effectively utilized by causing the bidirectional inverter to perform charging or discharging operations based on a target charge amount for the storage device, which is assumed from the predicted values ​​of the amount of power generated by the renewable energy power generation device and the amount of power consumed by the load. However, there is a problem in that when the predicted value and the actual power deviate due to a sudden change in the generated power caused by a change in weather or a sudden change in the load, the voltage value of the DC connection part may deviate from a predetermined value or a predetermined range.

[0005] The voltage value of the DC connection may deviate from a predetermined value or range, and if this occurs, the equipment connected to the DC power line may fail.

[0006] In view of this problem, an object of the present invention is to provide a power supply facility in which each DC device in the power supply facility stably supplies DC power. [Means for solving the problem]

[0007] In view of the above, the present invention provides a power supply facility including a first conversion device that is arranged between an AC power line and a DC power line and performs power conversion, a second conversion device that is arranged between the DC power line and a storage battery and performs power conversion, and a third conversion device that is arranged between the DC power line and a renewable energy power source and performs power conversion. In The first conversion device controls the voltage of the DC power line to a first voltage, and the second conversion device controls the voltage of the DC power line to a second voltage when the first conversion device cannot control the voltage of the DC power line to the first voltage and the voltage of the DC power line exceeds a second voltage set higher than the first voltage. Ruden power supply equipment the first conversion device and the third conversion device are connected to one end of a fourth conversion device by a first DC power line, and the other end of the fourth conversion device is connected to the second conversion device via the first DC power line; the fourth conversion device controls a ratio of a voltage of the first DC power line to a voltage of a second DC power line to a constant value; the first conversion device controls the voltage of the first DC power line to a voltage value obtained by multiplying the first voltage by the constant value; and the second conversion device controls the voltage of the second DC power line to the second voltage when the first conversion device cannot control the voltage of the first DC power line to a voltage value obtained by multiplying the first voltage by the constant value and the voltage of the second DC power line exceeds the second voltage. " [Effects of the Invention]

[0010] According to the present invention, each DC device in a power supply facility can actively switch control by referring to the voltage value of the DC power line without using an external command, thereby enabling a stable supply of DC power. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an example of the configuration of a power supply facility according to a first embodiment of the present invention; [Figure 2] FIG. 2 is a diagram showing a first example of control of the power of each component and the voltage VD of the DC power line when the present invention is applied. [Figure 3] FIG. 10 is a diagram showing a second example of control of the power of each component and the voltage VD of the DC power line when the present invention is applied. [Figure 4] FIG. 10 is a diagram showing a third example of control of the power of each component and the voltage VD of the DC power line when the present invention is applied. [Figure 5] FIG. 10 is a diagram showing a fourth example of control of the power of each component and the voltage VD of the DC power line when the present invention is applied. [Figure 6] FIG. 5 is a diagram showing a fifth example of control of the power of each component and the voltage VD of the DC power line when the present invention is applied. [Figure 7] FIG. 3 is a diagram showing another example of the configuration of the power supply facility according to the first embodiment of the present invention. [Figure 8] FIG. 4 is a diagram showing yet another configuration example of the power supply facility according to the first embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing a configuration example of a power supply facility according to a second embodiment of the present invention. [Figure 10] 10A and 10B are diagrams showing examples of control of the power of each component and the voltage VD of a DC power line when the second embodiment of the present invention is applied. [Figure 11] FIG. 10 is a diagram showing a configuration example of a power supply facility according to a third embodiment of the present invention. [Figure 12] 10A and 10B are diagrams showing examples of control of the power of each component and the voltage VD of a DC power line when the third embodiment of the present invention is applied. [Figure 13] FIG. 10 is a diagram showing a configuration example of a power supply facility according to a fourth embodiment of the present invention. [Figure 14] FIG. 10 is a diagram showing a configuration example of a power supply facility according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments. Those skilled in the art will be able to make various additions and modifications within the scope of the present invention. [Example]

[0013] FIG. 1 shows an example of the configuration of a power supply facility according to a first embodiment of the present invention. The power supply facility 1 includes a solar cell 2, a first DC / DC converter 3, a power storage device 4, an AC / DC inverter 5, a DC power line 6, and a power supply facility control unit 7. The solar cell 2 is connected to the first DC / DC converter 3. The DC power line 6 connects the output terminal of the first DC / DC converter 3, the power storage device 4, and a DC output terminal of the AC / DC inverter 5 in parallel. The AC output terminal of the AC / DC inverter 5 is connected to a distribution line 8 that is connected to an AC power source 9, and the AC / DC inverter 5 is capable of bidirectional power conversion. An AC load 10 is connected to the distribution line 8.

[0014] The power storage device 4 is composed of a storage battery 41 and a DC / DC converter 42. The DC / DC converter 42 is a bidirectional power conversion circuit, and the storage battery 41 can be charged and discharged by controlling the DC / DC converter 42. The storage battery 41 is, for example, a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. The power storage device 4 may be a stationary facility, or may be configured such that the storage battery 41 is an electrically-powered mobile object such as an electric vehicle, and the DC / DC converter 42 is a stationary charger / discharger.

[0015] In the power supply facility 1 of Fig. 1, the solar cell 2 may generally be a renewable energy power source such as photovoltaic power generation or wind power generation, and here, the case where photovoltaic power generation is used is shown. In the case of wind power generation, the wind power generation itself outputs AC, so the first DC / DC converter 3 is configured as an inverter that converts AC to DC. Despite such differences in configuration, the present invention can be applied to any of the above renewable energy power sources.

[0016] As illustrated in FIG. 1, the power supply facility 1 is configured with a first conversion device (AC / DC inverter 5) that is arranged between an AC power line 8 and a DC power line 6 and performs power conversion, a second conversion device (DC / DC converter 42) that is arranged between the DC power line 6 and the storage battery 4 and performs power conversion, and a third conversion device (first DC / DC converter 3) that is arranged between the DC power line 6 and a renewable energy power source 2 and performs power conversion.

[0017] In the present invention, the power supply facility 1 has two types of control functions: a power supply facility control unit 7 and control by voltage adjustment units 5V, 3V, and 4V arranged for each of the individual conversion devices 3, 42, and 5. The voltage adjustment units 5V, 3V, and 4V may have their functions within a control circuit (not shown) that each of the conversion devices 3, 42, and 5 has. As will be described in detail later, the power supply facility control unit 7 performs long-cycle control on the three sets of conversion devices 3, 42, and 5 described above on a scale of several seconds or minutes, while the control by the voltage adjustment units 5V, 3V, and 4V arranged for each of the individual conversion devices 3, 42, and 5 performs short-cycle control. The short-cycle control is performed in a shorter cycle than the long-cycle control.

[0018] The power supply facility control unit 7 operates as an EMS (Energy Management System). That is, it measures (not shown) the power received from the AC power source 9, the power consumption of the load 10, the power generated by the solar cell 2, the SOC (State of Charge) of the storage battery 41, etc., and determines the power flow within the power supply facility 1 from the viewpoints of the rated power of each device, the predicted power generation of the solar cell 2, the predicted power consumption of the load 10, the SOC of the storage battery 41, lifespan and degradation management, etc.

[0019] Then, the power supply facility control unit 7 issues control commands to the power storage device 4, such as a charge / discharge power command or a charge / discharge current command, upper and lower charge / discharge power limit values ​​or upper and lower charge / discharge current limit values, and upper and lower SOC limit values, and also issues control commands to the AC / DC inverter 5, such as upper and lower conversion power limit values. The commands are issued via wired or wireless communication at regular intervals (for example, at one-minute intervals). The power supply facility control unit 7 also issues control commands to the first DC / DC converter 3, the power storage device 4, and the AC / DC inverter 5 to start and stop their operations.

[0020] The power supply equipment control unit 7 issues these commands to the first DC / DC converter 3, the power storage device 4, and the AC / DC inverter 5 at long intervals, on the order of tens of seconds or minutes.

[0021] The first DC / DC converter 3 performs maximum power point tracking (MPPT) control on the power generated by the connected solar cell 2 and outputs it to the DC power line 6. The power storage device 4 also performs charge / discharge power or charge / discharge current control in accordance with commands from the power supply equipment control unit 7.

[0022] In contrast, the other control system, which is control by voltage adjustment units 5V, 3V, and 4V arranged for each individual conversion device 3, 42, and 5, detects the voltage VD of the DC power line 6 and controls it to the respective set voltage values ​​VD1, VD2 or VD4, VD3. The voltage adjustment unit 5V of the AC / DC inverter 5 is set to the voltage value VD1, the voltage adjustment unit 4V of the DC / DC converter 42 is set to the voltage values ​​VD2 and VD4, and the voltage adjustment unit 3V of the first DC / DC converter 3 is set to the voltage value VD3.

[0023] At this time, the magnitude relationship between the voltage values ​​is voltage value VD3 > voltage value VD2 > voltage value VD1, and normally voltage VD of DC power line 6 is controlled to voltage value VD1 by control by voltage adjustment unit 5V of AC / DC inverter 5, but when voltage VD of DC power line 6 increases, it is controlled to voltage value VD2 by control by voltage adjustment unit 4V of DC / DC converter 42, and when voltage VD of DC power line 6 increases further, it is controlled to voltage value VD3 by control by voltage adjustment unit 3V of first DC / DC converter 3. Voltage value VD4 will be described later.

[0024] Although it may not be possible to control the voltage to the target value VD, voltage control itself continues. The AC / DC inverter 5 always attempts to control the voltage to VD1, but the upper limit of the conversion power is reached, resulting in P3+P4>P5, and the voltage rising without being controlled to VD1. In this case, the power storage device starts voltage control to VD2, but the AC / DC inverter 5 continues its control operation (control to VD1). The same applies to the power storage device 4.

[0025] By applying the two types of control systems described above, the three sets of conversion devices 3, 42, and 5 will control the voltage of the DC power line 6 within the range of control commands regarding various long-term restrictions set by the power supply equipment control unit 7.

[0026] Specifically, this sharing control is executed as follows depending on the operating status of the power supply facility 1. First, the AC / DC inverter 5 controls the voltage VD of the DC power line 6 to a voltage value VD1. The voltage value VD1 is, for example, 350 V. The AC / DC inverter 5 controls the AC output power P5 so that the voltage VD of the DC power line 6 is controlled to the voltage value VD1. At this time, the sum of the output power P3 of the first DC / DC converter 3 and the discharge power P4 of the power storage device 4 is equal to the AC output power P5 of the AC / DC inverter 5 (P3 + P4 = P5). The first voltage VD1 is set from within a voltage range common to the input voltage ranges of the AC / DC inverter 5, first DC / DC converter 3, and power storage device 4, which are connected to the DC voltage line 6, excluding the maximum and minimum values.

[0027] When the voltage VD of the DC power line 6 is higher than the voltage value VD1, the AC / DC inverter 5 outputs AC power to the distribution line 8 side and supplies it to the load 10, thereby reducing the voltage VD of the DC power line 6 to the voltage value VD1. When the voltage VD of the DC power line 6 is lower than the voltage value VD1, the AC / DC inverter 5 receives power from the AC power source 9 from the distribution line 8 side and supplies the power to the power storage device 4, thereby increasing the voltage VD of the DC power line 6 to the voltage value VD1.

[0028] As described above, the AC / DC inverter 5 can control the voltage VD of the DC power line 6 to a voltage value VD1 by controlling the converted power. In this embodiment, power conversion from the DC side to the AC side is positive, and power conversion from the AC side to the DC side is negative.

[0029] However, the power that the AC / DC inverter 5 can convert is limited by its rated power. Furthermore, when the power supply equipment control unit 7 manages the reverse flow power and received power to the AC power source 9, the AC / DC inverter 5 is commanded upper and lower limit values ​​of the conversion power by the power supply equipment control unit 7. Therefore, the upper limit of the conversion power of the AC / DC inverter 5 is the minimum of the rated power of the AC / DC inverter 5 and the upper limit value of the conversion power commanded by the power supply equipment control unit 7, and the lower limit of the conversion power of the AC / DC inverter 5 is the maximum of the rated power of the AC / DC inverter 5 × (-1) and the lower limit value of the conversion power commanded by the power supply equipment control unit 7. Due to these upper and lower limit values ​​of the conversion power, there are cases where the AC / DC inverter 5 cannot control the voltage VD of the DC power line 6 to the voltage value VD1.

[0030] Figure 2 shows Example 1 of control of the power of each component and the voltage VD of the DC power line when the present invention is applied. First, the output power P3 of the first DC / DC converter 3, the discharge power P4 of the power storage device 4, and the AC output power P5 of the AC / DC inverter 5 are shown at the top of Figure 2 as the power of each component of the power supply facility 1. However, here, the converted power P5 of the AC / DC inverter 5 is assumed to be positive when output to the AC side and negative when input (received power) from the AC side. Also, the charge / discharge power P4 of the power storage device 4 is assumed to be positive when discharged and negative when charged. The output P3 of the first DC / DC converter 3 is assumed to be positive.

[0031] The lower part of FIG. 2 shows the relationship between the change in voltage VD of the DC power line over time and the voltage values ​​VD1, VD2, and VD3 set for each of the three sets.

[0032] According to the time notation shown on the horizontal axis at the top of Figure 2, the control cycle of the power supply equipment control unit 7 is T, which indicates that after a command is given at time 0, a command is given again at time T. In contrast, times T1 to T6 shown within the cycle T are the times when various events occur in the three sets of conversion devices 3, 42, and 5 in the power supply equipment 1. As is clear from this, the control of the power supply equipment 1 is long-cycle control, while the control by the voltage adjustment units 5V, 3V, and 4V arranged for each individual conversion device 3, 42, and 5 is short-cycle control.

[0033] 1, the long-period control power supply equipment control unit 7 provides upper and lower limit values ​​to the converters 42 and 5, and the converters 42 and 5 are operated within the given limits. However, for renewable energy sources, it is best to prioritize outputting the amount of power generated as is and not impose any special restrictions.

[0034] In the illustrated example, at time 0, the power supply equipment control unit 7 commands the AC / DC inverter 5 to set its upper limit of conversion power to 50 kW (the conversion power P5 is 40 kW at time 0), and the storage device 4 has its upper limit of charge / discharge power set to 20 kW and its lower limit of charge / discharge power set to -20 kW. However, in the illustrated example, the storage device 4 is discharging at 20 kW to supply power to the load 10. Also, the output of the first DC / DC converter 3 at time 0 is set to 20 kW.

[0035] At this time, the sum of the output P3 (20 kW) of the first DC / DC converter 3 and the discharge power P4 (20 kW) of the storage device 4 is 40 kW, which is less than the upper limit of the conversion power P5 of the AC / DC inverter 5. Therefore, by converting power by only 40 kW, the AC / DC inverter 5 can control the voltage VD of the DC power line 6 to the voltage value VD1.

[0036] From time 0 to time T1, when the output power of the first DC / DC converter 3 increases due to fluctuations in solar radiation, the AC / DC inverter 5 increases the converted power P5 to control the voltage VD of the DC power line 6 to the first voltage VD1. At time T1, the output power P3 of the first DC / DC converter 3 becomes 30 kW, and the converted power P5 of the AC / DC inverter 5 reaches an upper limit of 50 kW.

[0037] After time T1, when the output power P3 of the first DC / DC converter 3 increases further, the AC / DC inverter 5 is unable to increase the converted power P5 from 50 kW, and the voltage VD of the DC power line 6 rises from the first voltage VD1, and at time T2, it reaches a second voltage VD2 (e.g., 370 V) that is higher than the first voltage VD1 and lower than the third voltage VD3.

[0038] When the voltage VD of the DC power line 6 is equal to or higher than the second voltage VD2, this state is detected by the voltage adjustment unit 4V of the DC / DC converter 42, and the power storage device 4 stops the charge / discharge power control instructed by the power supply equipment control unit 7 and performs voltage control of the DC power line 6. The voltage control is performed, for example, by feedback control using the voltage VD of the DC power line 6 as a reference value.

[0039] In this embodiment, the power storage device 4 performs voltage control with the second voltage VD2 as a target value. The power storage device 4 also performs voltage control within a control range that maintains a discharge power equal to or greater than the charge / discharge power lower limit or a discharge current equal to or greater than the charge / discharge current lower limit commanded by the power supply equipment control unit 7. In this embodiment, it is assumed that the charge / discharge power lower limit is commanded to -20 kW. The upper limit of the discharge power or discharge current is the minimum value between the commanded charge / discharge power upper limit and 0 kW, or the minimum value between the commanded charge / discharge current upper limit and 0 A.

[0040] Furthermore, voltage control is performed only when the SOC of the storage battery 41 is below the SOC upper limit commanded by the power supply equipment control unit 7. This operation prevents overvoltage from being applied to devices connected to the DC power line 6. After time T2, the power storage device 4 performs voltage control with the second voltage as a target value by reducing the discharge power and increasing the charge power.

[0041] At time T3, the discharge power of the storage device 4 reaches -20 kW (charge power 20 kW). Even if the output power P3 of the first DC / DC converter 3 increases further after time T3, the storage device 4 cannot increase its charge power, so the voltage VD of the DC power line 6 further rises from the second voltage VD2, and at time T4, it reaches a third voltage VD3 (e.g., 390 V) that is higher than the second voltage VD2 and lower than the maximum DC voltage. The maximum DC voltage is the input voltage upper limit of the device that has the lowest withstand voltage among the AC / DC inverter 5, the first DC / DC converter 3, and the storage device 4 connected to the DC voltage line 6.

[0042] As shown in the lower part of Figure 2, in the above operation, the relationship between the second voltage VD2 and the third voltage VD3 is set so that the third voltage VD3 is higher than the second voltage VD2. This means that the control switching of the first DC / DC converter 3 is performed after the control switching of the power storage device 4. With this setting, the first DC / DC converter 3 switches from MPPT control to voltage control, which results in the suppression of solar power generation, being the last resort, and power generation by the solar cell 2 can be continued as long as possible.

[0043] If the magnitude relationship of these voltages were reversed, and the second voltage VD2 were set higher than the third voltage VD3, and the third voltage VD3 were set higher than the first voltage VD1, power generation by the solar cell 2 would be suppressed before the storage device 4 switches control to increase the charging power, resulting in a waste of the power generation capacity of the solar cell 2.

[0044] When the voltage VD of the DC power line 6 is equal to or higher than the third voltage VD3, this state is detected by the voltage adjustment unit 3V of the first DC / DC converter 3, and the first DC / DC converter 3 stops MPPT control and performs voltage control of the DC power line 6. At this time, in this embodiment, the first DC / DC converter 3 performs voltage control with the third voltage VD3 as a target value. When the voltage VD of the DC power line 6 is equal to or higher than the third voltage VD3, there is no load or storage battery that can consume or charge all of the power generated by the solar cell 2, so the power generated by the solar cell 2 must be suppressed. By switching to voltage control as described above, power generation by the solar cell 2 is suppressed and overvoltage application to devices connected to the DC power line 6 is prevented.

[0045] After time T4, when the solar radiation decreases and the power generated by the solar cell 2 decreases, the voltage VD of the DC power line 6 drops below the third voltage VD3 at time T5. At this time, the first DC / DC converter 3 ends the voltage control of the DC power line 6 and resumes MPPT control. Note that the power storage device 4 continues to control the voltage VD of the DC power line 6 to the second voltage.

[0046] When the power generated by the solar cell 2 further decreases, at time T6, the voltage VD of the DC power line 6 drops below the second voltage VD2. At this time, the power storage device 4 ends the voltage control of the DC power line 6 and resumes the charge / discharge power control commanded by the power supply equipment control unit 7. Then, the voltage VD of the DC power line 6 is controlled to the first voltage VD1 by the voltage control of the AC / DC inverter from time T7 onwards.

[0047] At time T when a new command is received from the power supply equipment control unit 7, the voltage VD of the DC power line 6 is the first voltage VD1. At this time, the upper limit of the conversion power of the AC / DC inverter 5 is updated to the minimum of the rated power of the AC / DC inverter 5 and the conversion power upper limit value received from the power supply equipment control unit 7 at time T. Furthermore, the lower limit of the conversion power of the AC / DC inverter 5 is the maximum of the rated power of the AC / DC inverter 5 × (-1) and the conversion power lower limit value commanded by the power supply equipment control unit 7. The power storage device 4 operates in accordance with the charge / discharge power command or charge / discharge current command received from the power supply equipment control unit 7 at time T. Furthermore, the charge / discharge power upper and lower limit values ​​or charge / discharge current upper and lower limit values, and SOC upper and lower limit values ​​are updated. The power after time T in FIG. 2 shows a case where the upper limit of the conversion power of the AC / DC inverter 5 is updated to 50 kW and the power storage device 4 discharges at the new charge / discharge power command value of 10 kW.

[0048] Fig. 3 shows a second control example of the power of each component and the voltage VD of the DC power line when the present invention is applied. The control example up to time T5 is the same as the first control example shown in Fig. 2, so a description thereof will be omitted. In Fig. 3, at time T, the first DC / DC converter 3 executes MPPT control, and the power storage device 4 controls the voltage VD of the DC power line 6 to the second voltage. In this example, the power storage device 4 is assumed to be operating with a discharge power of 5 kW.

[0049] When time T arrives when voltage VD of DC power line 6 is equal to or greater than second voltage VD2 and less than third voltage VD3, and AC / DC inverter 5 and power storage device 4 receive a new command from power supply equipment control unit 7, the upper limit of the conversion power of AC / DC inverter 5 is updated to the minimum value between the rated power of AC / DC inverter 5 and the upper limit power of conversion power received from power supply equipment control unit 7 at time T, as in the description in Fig. 2. In Fig. 3, it is assumed that the upper limit of the conversion power of AC / DC inverter 5 is updated to 50 kW at time T.

[0050] The power storage device 4 updates the upper and lower limit values ​​of the charge / discharge power or the upper and lower limit values ​​of the charge / discharge current, and the upper and lower limit values ​​of the SOC to new values ​​received from the power supply equipment control unit 7. The power storage device 4 also compares the charge / discharge power command or the charge / discharge current command (referred to as a command value in this embodiment) received from the power supply equipment control unit 7 at time T with the actual charge / discharge power or the actual charge / discharge current (referred to as an actual value in this embodiment) at time T, with the power and current in the discharging direction being positive. If the command value is smaller than the actual value, the power storage device 4 ends the voltage control of the DC power line 6 and performs charge / discharge power control in accordance with the command value. If the command value is larger than the actual value, the power storage device 4 continues the voltage control of the DC power line 6. However, the command value received at time T is retained and is used as a command value by the power supply equipment control unit 7 when the power storage device 4 ends the voltage control of the DC power line 6 and resumes charge / discharge power control.

[0051] 3, the discharge power of the power storage device 4 immediately before time T is 5 kW. At time T, when the power storage device 4 receives a charge / discharge power command to discharge -10 kW (charge 10 kW) from the power supply equipment control unit 7, the command value of -10 kW is smaller than the actual value of 5 kW, so the power storage device 4 ends the voltage control of the DC power line 6 and performs discharge power control in accordance with the command value -10 kW. At this time, the voltage VD of the DC power line 6 is controlled to the first voltage VD1 by the voltage control of the AC / DC inverter.

[0052] Figure 4 shows control example 3 of the power of each component and the voltage VD of the DC power line when the present invention is applied. The control example 3 up to time T4 is the same as control example 1 shown in Figure 2, so a description thereof will be omitted. In Figure 4, at time T, the first DC / DC converter 3 controls the voltage VD of the DC power line 6 to a third voltage VD3. It is assumed that the power storage device 4 is operating at a discharge power of -20 kW (charge power of 20 kW).

[0053] When time T arrives while voltage VD of DC power line 6 is equal to or higher than third voltage VD3 and AC / DC inverter 5 and power storage device 4 receive new commands from power supply equipment control unit 7, the upper limit of the conversion power of AC / DC inverter 5 is updated to the minimum value between the rated power of AC / DC inverter 5 and the conversion power upper limit value received from power supply equipment control unit 7 at time T, as in the description of FIG. 2 .

[0054] The power storage device 4 updates the charge / discharge power upper and lower limit values ​​or charge / discharge current upper and lower limit values, and SOC upper and lower limit values ​​to the new commands received from the power supply equipment control unit 7. The power storage device 4 also holds the charge / discharge power command or charge / discharge current command received from the power supply equipment control unit 7 at time T and continues voltage control of the DC power line 6. The held command value is used as the command value from the power supply equipment control unit 7 when the power storage device 4 ends voltage control of the DC power line 6 and resumes charge / discharge power control.

[0055] At time T, the upper limit of the conversion power of the AC / DC inverter 5 is updated to 50 kW, and the upper and lower limits of the charge / discharge power of the power storage device 4 are updated to an upper limit of 20 kW and a lower limit of −40 kW. Furthermore, the charge / discharge power command for the power storage device 4 is set to −20 kW. At this time, the voltage VD of the DC power line 6 is the third voltage VD3, so the power storage device 4 continues to control the voltage of the DC power line 6. Before time T, the lower limit of the charge / discharge power was −20 kW. However, at time T, the lower limit of the charge / discharge power is updated to −40 kW, so the discharge power of the power storage device 4 decreases. As a result of this operation, at time T7, the voltage VD of the DC power line 6 drops from the third voltage VD3 to the second voltage VD2. The first DC / DC converter 3 then terminates the voltage control of the DC power line 6 and resumes MPPT control. The power storage device 4 then continues to control the voltage VD of the DC power line 6 to the second voltage. In addition to the above operations, a control operation can also be performed in which the magnitude relationship between the voltage values ​​is set as voltage value VD3 > voltage value VD1 > voltage value VD2, and voltage VD of DC power line 6 is normally controlled to voltage value VD2 by voltage adjustment unit 4V of DC / DC converter 42, but when voltage VD of DC power line 6 rises, voltage adjustment unit 5V of AC / DC inverter 5 controls it to voltage value VD1, and when voltage VD of DC power line 6 rises further, voltage adjustment unit 3V of first DC / DC converter 3 controls it to voltage value VD3. In this operation, power supply facility control unit 7 commands AC / DC inverter 5 to output AC output power, and when voltage VD of DC power line 6 is less than voltage value VD1, AC / DC inverter 5 outputs AC output power P5 to AC power line 8 in accordance with the command. However, if voltage adjustment unit 4V of DC / DC converter 42 is unable to control voltage VD of DC power line 6 to voltage value VD2 and voltage VD rises and exceeds voltage value VD1, voltage adjustment unit 5V of AC / DC inverter 5 controls voltage VD to voltage value VD1. At this time, AC / DC inverter 5 determines AC output power P5 within the range of upper and lower conversion power limits commanded by power supply equipment control unit 7. This operation makes it possible to configure power supply equipment 1 that commands and controls output power P5 to AC power line 8.

[0056] Figure 5 shows a fourth example of control of the power of each component and the voltage VD of the DC power line when the present invention is applied. Figures 2, 3, and 4 show the response when the voltage VD of the DC power line rises, while Figures 5 and 6 show the response when the voltage VD of the DC power line drops.

[0057] 5 , at time 0, the lower limit of the conversion power of the AC / DC inverter 5 is set to −50 kW, and the charge / discharge power upper limit of the power storage device 4 is set to 60 kW and the charge / discharge power lower limit is set to −60 kW. Furthermore, the power storage device 4 is discharging at −60 kW in response to a command from the power supply equipment control unit 7. Furthermore, at time 0, the output of the first DC / DC converter 3 is set to 20 kW. At this time, the sum of the output of the first DC / DC converter 3 and the discharge power of the power storage device 4 is −40 kW, which is greater than or equal to the lower limit of the conversion power of the AC / DC inverter 5. Therefore, the AC / DC inverter 5 converts power by −40 kW (receives power of 40 kW from the distribution line 8), thereby controlling the voltage VD of the DC power line 6 to the first voltage VD1.

[0058] From time 0 to time T1, when the output power of the first DC / DC converter 3 decreases due to fluctuations in solar radiation, the AC / DC inverter 5 reduces the converted power to control the voltage VD of the DC power line 6 to the first voltage VD. At time T1, the output power of the first DC / DC converter 3 becomes 10 kW, and the converted power of the AC / DC inverter 5 reaches the lower limit value of −50 kW.

[0059] After time T1, when the output power of the first DC / DC converter 3 further decreases, the AC / DC inverter 5 is unable to reduce the converted power from −50 kW, and the voltage VD of the DC power line 6 drops from the first voltage VD1. Then, at time T2, the voltage VD reaches a fourth voltage VD4 (e.g., 340 V) that is lower than the first voltage VD1. The fourth voltage VD4 is set to a value higher than the minimum DC voltage of the power supply facility 1. The minimum DC voltage is set to a value (e.g., 320 V) higher than the maximum AC voltage (e.g., 220√2 V) at the AC output terminal of the AC / DC inverter 5. When the voltage VD of the DC power line 6 drops below the minimum DC voltage, all of the devices connected to the DC power line 6 (the first DC / DC converter 3, the power storage device 4, and the AC / DC inverter 5) stop operating.

[0060] When the voltage VD of the DC power line 6 is equal to or lower than the fourth voltage VD4, the power storage device 4 stops the charge / discharge power control instructed by the power supply equipment control unit 7 and executes voltage control of the DC power line 6. In this embodiment, the power storage device 4 executes voltage control with the fourth voltage VD4 as a target value, with the discharge power less than the charge / discharge power upper limit or the discharge current less than the charge / discharge current upper limit. Furthermore, the voltage control is executed only when the SOC of the storage battery 41 is equal to or higher than the SOC lower limit instructed by the power supply equipment control unit 7. This operation ensures the voltage required to operate the devices connected to the DC power line 6.

[0061] After time T2, power storage device 4 continues voltage control with the fourth voltage as the target value due to the increase in discharge power.

[0062] After time T3, when the output power of the first DC / DC converter 3 increases, the power storage device 4 continues voltage control with the fourth voltage VD4 as a target value due to a decrease in discharge power. Then, when the output power of the first DC / DC converter 3 further increases, at time T4, the voltage VD of the DC power line 6 becomes equal to or higher than the fourth voltage VD4. At this time, the power storage device 4 ends the voltage control of the DC power line 6 and resumes the charge / discharge power control commanded by the power supply equipment control unit 7. Then, after time T5, the voltage VD of the DC power line 6 is controlled to the first voltage VD1 by voltage control of the AC / DC inverter.

[0063] At time T when a new command is received from the power supply equipment control unit 7, the voltage VD of the DC power line 6 is the first voltage VD1. At this time, the upper limit of the conversion power of the AC / DC inverter 5 is updated to the minimum of the rated power of the AC / DC inverter 5 and the conversion power upper limit value received from the power supply equipment control unit 7 at time T. In addition, the lower limit of the conversion power of the AC / DC inverter 5 is updated to the maximum of the rated power of the AC / DC inverter 5 × (-1) and the conversion power lower limit value commanded from the power supply equipment control unit 7.

[0064] The power storage device 4 operates in accordance with the charge / discharge power command or charge / discharge current command received from the power supply equipment control unit 7 at time T. The power storage device 4 also updates the charge / discharge power upper and lower limit values ​​or charge / discharge current upper and lower limit values, and the SOC upper and lower limit values. The power after time T in Fig. 5 shows a case where the lower limit of the converted power of the AC / DC inverter 5 is updated to -50 kW, and the power storage device 4 discharges at the new charge / discharge power command value of -50 kW.

[0065] Fig. 6 shows control example 5 of the power of each component and the voltage VD of the DC power line when the present invention is applied. The process up to time T3 is the same as control example 4 shown in Fig. 5, and therefore a description thereof will be omitted. In Fig. 6, at time T, the first DC / DC converter 3 executes MPPT control, and the power storage device 4 controls the voltage VD of the DC power line 6 to a fourth voltage. In this example, it is assumed that the power storage device 4 is operating at a discharge power of -55 kW (charge power of 55 kW).

[0066] When time T arrives while voltage VD of DC power line 6 is equal to or higher than fourth voltage VD4 and lower than first voltage VD1, and AC / DC inverter 5 and power storage device 4 receive a new command from power supply equipment control unit 7, the upper limit of the conversion power of AC / DC inverter 5 is updated to the minimum value of the rated power of AC / DC inverter 5 and the upper limit power of conversion power received from power supply equipment control unit 7 at time T, as in the description with reference to FIG. 5 . Also, the lower limit of the conversion power of AC / DC inverter 5 is updated to the maximum value of the rated power of AC / DC inverter 5×(−1) and the lower limit value of the conversion power commanded from power supply equipment control unit 7.

[0067] The power storage device 4 updates the upper and lower limit values ​​of the charge / discharge power or the charge / discharge current, and the upper and lower limit values ​​of the SOC to new values ​​received from the power supply equipment control unit 7. The power storage device 4 also compares the charge / discharge power command or the charge / discharge current command (referred to as a command value in this embodiment) received from the power supply equipment control unit 7 at time T with the actual charge / discharge power or the actual charge / discharge current (referred to as an actual value in this embodiment) at time T, with the power and current in the discharging direction being positive. If the command value is larger than the actual value, the power storage device 4 ends the voltage control of the DC power line 6 and performs charge / discharge power control in accordance with the command value. If the command value is smaller than the actual value, the power storage device 4 continues the voltage control of the DC power line 6. However, the command value received at time T is retained and is used as a command value by the power supply equipment control unit 7 when the power storage device 4 ends the voltage control of the DC power line 6 and resumes charge / discharge power control.

[0068] 6, the discharge power of the power storage device 4 immediately before time T is -55 kW. At time T, when the power storage device 4 receives a charge / discharge power command to discharge -40 kW from the power supply equipment control unit 7, the command value of -40 kW is larger than the actual value of -55 kW, so the power storage device 4 ends the voltage control of the DC power line 6 and performs discharge power control in accordance with the command value -40 kW. At this time, the voltage VD of the DC power line 6 is controlled to the first voltage VD1 by the voltage control of the AC / DC inverter.

[0069] FIG. 7 shows another example of the configuration of the power supply facility according to the first embodiment of the present invention. In FIG. 7, an electric vehicle connection unit 611 is installed on the DC power line 6. An electric vehicle 11 is connected to the DC power line 6 via the electric vehicle connection unit 611. The electric vehicle connection unit 611 is a cable connector branched from the DC power line 6 and serves as an electrical contact point between the electric vehicle 11 and the DC power line 6. The electric vehicle 11 may be, for example, an electric automobile, an electric agricultural machine, a drone, or the like, and is not necessarily always provided in the power supply facility 1. The electric vehicle 11 has a storage battery 41 and a DC / DC converter 42, and can charge the storage battery 41 by controlling the charging power itself using a DC power supply. Furthermore, the power stored in the storage battery 41 can be discharged via DC by controlling the DC / DC converter 42.

[0070] The power supply facility 7 can issue charge / discharge power commands or charge / discharge current commands, upper and lower limit values ​​for charge / discharge current, and upper and lower limit values ​​for SOC to the electric vehicle 11, and can operate in the same manner as the configuration example shown in FIG. 1 and the examples of power and DC power line voltage of the power supply facility shown in FIGS. 2 to 6.

[0071] In FIG. 7, the electric vehicle 11 may have a structure that does not include the DC / DC converter 42, and in this case, it may be connected via a separate external DC / DC converter 42.

[0072] FIG. 8 shows yet another example of the configuration of the power supply facility according to the first embodiment of the present invention. This is a connection example in which the electric vehicle 11 does not have a DC / DC converter 42. In FIG. 8, one end of the DC / DC converter 42 is connected to the DC power line 6, and an electric vehicle connection unit 611 is installed at the other end of the DC / DC converter 42. The electric vehicle 12 is connected to the DC power line 6 via the DC / DC converter 42 and the electric vehicle connection unit 611. The electric vehicle connection unit 611 is a cable connector for supplying the output of the DC / DC converter 42 to the electric vehicle 12. The electric vehicle 12 may be, for example, an electric automobile, an electric agricultural machine, a drone, or the like, and is not necessarily always provided in the power supply facility 1. The electric vehicle 12 has a storage battery 41, and the storage battery 41 is charged and discharged by the charge / discharge power control of the DC / DC converter 42. The configuration shown in FIG. 8 can also perform the same operation as the configuration shown in FIG. 7. [Example]

[0073] 9 shows a configuration example of a power supply facility according to a second embodiment of the present invention. In this embodiment, the power supply facility 1 includes a received power measurement unit 12 in addition to the configuration shown in the first embodiment. The following describes the differences from the first embodiment.

[0074] This embodiment is applied to a power supply facility 1 and a load 10 connected to an AC power source 9 on the condition that reverse power flow is not permitted. In a connection that does not permit reverse power flow, a reverse power flow relay is installed at the power receiving point, and the circuit breaker opens when reverse power flow occurs. When power is supplied to the load 10 using the power generated by the solar cell 2 and the power discharged from the power storage device 4, the occurrence of reverse power flow must be prevented so that the circuit breaker does not open.

[0075] The power supply facility 7 issues a command for the upper limit of the conversion power to the AC / DC inverter 5 and a command for charging / discharging power or a command for charging / discharging current to the battery 4 at regular intervals (for example, one minute). Therefore, if the power consumption of the load 10 decreases gradually over a period of time equal to or longer than the regular interval, reverse power flow can be prevented. However, if the power consumption of the load 10 decreases suddenly within a period of time shorter than the regular interval, the command value of the power supply facility 7 cannot be updated in time, causing reverse power flow and opening the circuit breaker. If the command period of the power supply facility 7 is set to a short period of time (for example, 0.1 seconds) to prevent reverse power flow, the installation cost of the power supply facility 7 will increase.

[0076] Therefore, in this embodiment, received power measurement unit 12 measures the power at receiving point 91 of AC power supply 9, and transmits AC output stop command 13 to AC / DC inverter 5 while the received power is equal to or less than a predetermined value (for example, 1 kW). When AC / DC inverter 5 receives AC output stop command 13, it sets the upper limit of the conversion power to 0 kW from the time of reception until it receives a new conversion power upper limit command from power supply equipment 7. After the time it receives a new conversion power upper limit command from power supply equipment 7, the upper limit of the conversion power of AC / DC inverter 5 is set to the minimum of the rated power of AC / DC inverter 5 and the conversion power upper limit commanded by power supply equipment control unit 7.

[0077] Fig. 10 shows an example of control of the power of each component and the voltage VD of the DC power line when the second embodiment of the present invention is applied. In this embodiment, as in the first embodiment, the converted power P5 of the AC / DC inverter 5 is positive when output to the AC side and negative when input (received power) from the AC side. Furthermore, the charging / discharging power P4 of the storage device 4 is positive when discharging and negative when charging. The output P3 of the first DC / DC converter 3 is positive.

[0078] The time when the power storage device 4 and AC / DC inverter 5 receive a command from the power supply equipment control unit 7 is set to 0. The power supply equipment control unit 7 transmits commands at a constant cycle T. Therefore, the next time the power storage device 4 and AC / DC inverter 5 receive a command is at time T.

[0079] At time 0, the upper limit of the conversion power P5 of the AC / DC inverter 5 is set to 50 kW in response to a command from the power supply equipment control unit 7. The charge / discharge power upper limit of the power storage device 4 is set to 30 kW and the charge / discharge power lower limit is set to -30 kW, and the power storage device 4 is discharging at 30 kW to supply power to the load 10. For simplicity's sake, the output of the first DC / DC converter 3 is set to a constant 10 kW at time 0. At this time, the sum of the output P3 of the first DC / DC converter 3 and the discharge power P4 of the power storage device 4 is 40 kW, which is less than the upper limit of the conversion power P5 of the AC / DC inverter 5. Therefore, the AC / DC inverter 5 can control the voltage VD of the DC power line 6 to the first voltage VD1 by converting power by 40 kW.

[0080] When AC / DC inverter 5 receives AC output stop command 13 at time T1, the upper limit of conversion power P5 of AC / DC inverter 5 is updated to 0 kW. Therefore, the conversion power of AC / DC inverter 5 was 40 kW until time T1, but becomes 0 kW after time T1. Then, voltage VD of DC power line 6 rises, and at time T2, voltage VD of DC power line 6 exceeds second voltage VD2.

[0081] When the voltage VD of the DC power line 6 is equal to or higher than the second voltage VD2, the power storage device 4 stops the charge / discharge power control instructed by the power supply equipment control unit 7 and executes voltage control of the DC power line 6. At this time, in this embodiment, the power storage device 4 executes voltage control with the second voltage VD2 as a target value. Furthermore, the power storage device 4 executes voltage control with a discharge power equal to or higher than the charge / discharge power lower limit value instructed by the power supply equipment control unit 7 or a discharge current equal to or higher than the charge / discharge current lower limit value instructed by the power supply equipment control unit 7. In this embodiment, it is assumed that the charge / discharge power lower limit value is instructed to be -30 kW.

[0082] At time T, the upper limit of the conversion power P5 of the AC / DC inverter 5 is updated to the minimum value of the rated power of the AC / DC inverter 5 and the conversion power upper limit value received from the power supply equipment control unit 7. In this embodiment, it is assumed that it is updated to 30 kW.

[0083] The power storage device 4 updates the upper and lower limit values ​​of the charge / discharge power or the upper and lower limit values ​​of the charge / discharge current, and the upper and lower limit values ​​of the SOC to the new upper and lower limit values ​​received from the power supply equipment control unit 7.

[0084] At time T, the voltage VD of the DC power line 6 is equal to or greater than the second voltage VD2 and less than the third voltage VD3, so the storage device 4 compares the charge / discharge power command or charge / discharge current command (referred to as a command value in this embodiment) received from the power supply equipment control unit 7 at time T with the actual charge / discharge power or charge / discharge current (referred to as an actual value in this embodiment) at time T, with the power and current in the discharging direction being positive.

[0085] If the command value is smaller than the actual value, the storage device 4 ends the voltage control of the DC power line 6 and performs charge / discharge power control in accordance with the command value. If the command value is larger than the actual value, the storage device 4 continues the voltage control of the DC power line 6. In this embodiment, it is assumed that a command value of 10 kW, which is larger than the actual value, is received. In this case, the storage device 4 continues the voltage control of the DC power line 6.

[0086] After time T, the AC / DC inverter 5 starts controlling the voltage VD of the DC power line 6 to a first voltage VD1 with an upper limit of the converted power being 30 kW. Meanwhile, the power storage device 4 continues to control the voltage of the DC power line 6, and increases its discharge power in accordance with the increase in the converted power of the AC / DC inverter 5. At time T3, when the charge / discharge power of the power storage device 4 reaches the charge / discharge power of 10 kW commanded by the power supply equipment control unit 7 at time T, the power storage device 4 ends the voltage control of the DC power line 6 and performs charge / discharge power control at 10 kW commanded by the power supply equipment control unit 7. Then, the voltage VD of the DC power line 6 is controlled to the first voltage VD1 by the voltage control of the AC / DC inverter.

[0087] In this embodiment, the power storage device 4 can be replaced with the configuration of the electric vehicle connection unit 611 and the electric vehicle 11 shown in FIG. 7 of the first embodiment. [Example]

[0088] 11 shows a configuration example of a power supply facility according to a third embodiment of the present invention. In this embodiment, in addition to the power storage device 4, a power storage device 4A is connected to a DC power line 6. Like the power storage device 4, the power storage device 4A is composed of a storage battery 41A and a DC / DC converter 42A, and can charge and discharge the storage battery 4A by controlling the DC / DC converter 42A. Differences from the first and second embodiments will be described below.

[0089] In this embodiment, when the voltage VD of the DC power line 6 becomes equal to or higher than the second voltage VD2 or lower than the fourth voltage VD4, if the power storage device 4 and the power storage device 4A each independently control the voltage of the DC power line 6, their voltage controls may interfere with each other, resulting in an unstable voltage VD of the DC power line 6. Therefore, when two or more power storage devices are connected to the DC power line 6, the power storage devices control the voltage of the DC power line 6 in one of the following two ways.

[0090] The first is droop control. The power supply equipment control unit 7 transmits a charge / discharge power command or a charge / discharge current command, a charge / discharge power upper / lower limit command or a charge / discharge current upper / lower limit command, and an SOC upper / lower limit command to the power storage device 4 and the power storage device 4A. A droop gain is set in advance for the power storage device 4 and the power storage device 4A. When the voltage VD of the DC power line 6 is equal to or higher than the second voltage VD2 or equal to or lower than the fourth voltage VD4, the power storage device 4 and the power storage device 4A control the voltage VD of the DC power line 6 to the second voltage VD2 or the fourth voltage VD4 using the droop gain.

[0091] The droop gain may be sequentially transmitted from the power supply equipment control unit 7. That is, the power supply equipment control unit 7 transmits a charge / discharge power command or a charge / discharge current command, a charge / discharge power upper / lower limit command or a charge / discharge current upper / lower limit command, an SOC upper / lower limit command, and the droop gain to the power storage device 4 and the power storage device 4A. When the voltage VD of the DC power line 6 is equal to or higher than the second voltage VD2 or equal to or lower than the fourth voltage VD4, the power storage device 4 and the power storage device 4A perform droop control in accordance with the droop gain received from the power supply equipment control unit 7, and control the voltage VD of the DC power line 6 to the second voltage VD2 or the fourth voltage VD4.

[0092] However, when the charge / discharge power or charge / discharge current determined according to the droop gain is outside the range of the charge / discharge power upper and lower limit values ​​or charge / discharge current upper and lower limit values ​​commanded by the power supply equipment control unit 7, the power storage device 4 and the power storage device 4A perform charging and discharging at the commanded charge / discharge power upper and lower limit values ​​or charge / discharge current upper and lower limit values. Also, when the SOC of the storage battery 41 and the storage battery 41A reaches the commanded SOC upper limit value, the lower limit value of the discharge power is set to 0 kW and no charging is performed, and when the SOC reaches the commanded SOC lower limit value, the upper limit value of the discharge power is set to 0 kW and no discharging is performed.

[0093] The second method is to set a voltage control switching priority for the power storage device. In this method, the power storage device stops the charge / discharge power control commanded by the power supply facility control unit 7 and sets a second voltage DV2 and a fourth voltage DV4, which are thresholds for executing voltage control of the DC power line 6, for each power storage device connected to the DC power line 6.

[0094] In this embodiment, the power storage device 4 suspends the charge / discharge power control instructed by the power supply equipment control unit 7 at the second voltage VD2 and the fourth voltage VD4, and executes voltage control of the DC power line 6. Furthermore, the power storage device 4A suspends the charge / discharge power control instructed by the power supply equipment control unit 7 at the second voltage VD2A and the fourth voltage VD4A, and executes voltage control of the DC power line 6.

[0095] The magnitude relationship between the second voltage VD2 and the second voltage VD2A and the magnitude relationship between the fourth voltage VD4 and the fourth voltage VD4A are determined independently, and the voltage control switching priority is reflected in these magnitude relationships. Here, the maximum values ​​of the second voltage VD2 and the second voltage VD2A are set to be less than the third voltage, and the minimum values ​​of the second voltage VD2 and the second voltage VD2A are set to be higher than the first voltage. Also, the maximum values ​​of the fourth voltage VD4 and the fourth voltage VD4A are set to be less than the first voltage, and the minimum values ​​of the fourth voltage VD4 and the fourth voltage VD4A are set to be higher than the minimum DC voltage.

[0096] The second voltage VD2, the second voltage VD2A, the fourth voltage VD4, and the fourth voltage VD4A are determined by a command from the power supply equipment control unit 7, an input from a source other than the power supply equipment control unit 7 that the power storage device 4 and the power storage device 4A have, or the power storage device 4 and the power storage device 4A themselves. In this embodiment, they are determined by a command from the power supply equipment control unit 7, and are in the order of first voltage VD1<second voltage VD2<second voltage VD2A<third voltage VD3, first voltage VD1>fourth voltage VD4>fourth voltage VD4A>minimum DC voltage.

[0097] 12 shows an example of control of the power of each component and the voltage VD of the DC power line when the third embodiment of the present invention is applied. In this figure, the time when the power storage devices 4, 4A, and AC / DC inverter 5 receive commands from the power supply equipment control unit 7 is set to 0. The power supply equipment control unit 7 transmits commands at a constant cycle T. Therefore, the next time the power storage devices 4, 4A, and AC / DC inverter 5 receive a command is at time T.

[0098] At time 0, the upper limit of conversion power P5 of AC / DC inverter 5 is set to 50 kW in response to a command from power supply equipment control unit 7. The charge / discharge power upper limit values ​​of power storage device 4 and power storage device 4A are set to 10 kW and the charge / discharge power lower limit values ​​are set to -20 kW, and power is being discharged at 10 kW to supply power to load 10. Also, at time 0, the output of first DC / DC converter 3 is set to 20 kW. At this time, the sum of the output of first DC / DC converter 3 and the discharge power of power storage device 4 and power storage device 4A is 40 kW, which is less than the upper limit of conversion power P5 of AC / DC inverter 5. Therefore, by performing power conversion by 40 kW, AC / DC inverter 5 can control voltage VD of DC power line 6 to first voltage VD1.

[0099] From time 0 to time T1, when the output power P3 of the first DC / DC converter 3 increases due to fluctuations in solar radiation, the AC / DC inverter 5 increases the converted power P5 to control the voltage VD of the DC power line 6 to the first voltage VD1. At time T1, the output power P3 of the first DC / DC converter 3 becomes 30 kW, and the converted power P5 of the AC / DC inverter 5 reaches an upper limit of 50 kW.

[0100] After time T1, when the output power of the first DC / DC converter 3 increases further, the AC / DC inverter 5 cannot increase the converted power P5 from 50 kW, and the voltage VD of the DC power line 6 rises from the first voltage VD1, and then, at time T2, it reaches a second voltage VD2 (e.g., 365 V) that is higher than the first voltage VD1.

[0101] When the voltage VD of the DC power line 6 is equal to or higher than the second voltage VD2, the power storage device 4 stops the charge / discharge power control instructed by the power supply equipment control unit 7 and executes voltage control of the DC power line 6. At this time, in this embodiment, the power storage device 4 executes voltage control with the second voltage VD2 as a target value. Furthermore, the power storage device 4 executes voltage control with a discharge power equal to or higher than the charge / discharge power lower limit value instructed by the power supply equipment control unit 7 or a discharge current equal to or higher than the charge / discharge current lower limit value instructed by the power supply equipment control unit 7. In this embodiment, -20 kW is instructed as the charge / discharge power lower limit value.

[0102] Meanwhile, at this time, the power storage device 4A continues the charge / discharge power control commanded by the power supply equipment control unit 7. After time T2, the power storage device 4 executes voltage control with the second voltage VD2 as a target value due to the decrease in discharge power.

[0103] At time T3, the discharge power of the power storage device 4 reaches -20 kW. After time T3, even if the output power P3 of the first DC / DC converter 3 increases further, the power storage device 4 cannot increase the charging power, and therefore the voltage VD of the DC power line 6 further increases from the second voltage VD2, and at time T4, reaches a second voltage VD2A (e.g., 375 V) that is higher than the second voltage VD2.

[0104] When the voltage VD of the DC power line 6 is equal to or higher than the second voltage VD2A, the power storage device 4A stops the charge / discharge power control instructed by the power supply equipment control unit 7 and executes voltage control of the DC power line 6. At this time, in this embodiment, the power storage device 4A executes voltage control with the second voltage VD2A as a target value. Furthermore, the power storage device 4A executes voltage control with a discharge power equal to or higher than the charge / discharge power lower limit value instructed by the power supply equipment control unit 7 or a discharge current equal to or higher than the charge / discharge current lower limit value instructed by the power supply equipment control unit 7. In this embodiment, -20 kW is instructed as the charge / discharge power lower limit value.

[0105] After time T4, the power storage device 4A executes voltage control with the second voltage VD2A as a target value due to a decrease in discharge power. At this time, if the solar radiation decreases and the power generated by the solar cell 2 decreases, the voltage VD of the DC power line 6 becomes less than the second voltage VD2A at time T5. At this time, the power storage device 4A ends the voltage control of the DC power line 6 and resumes the charge / discharge power control commanded by the power supply equipment control unit 7. Then, the voltage VD of the DC power line 6 is controlled to the second voltage VD2 by the voltage control of the power storage device 4.

[0106] Similarly, after time T5, when the solar radiation decreases and the power generated by the solar cell 2 decreases, the voltage VD of the DC power line 6 becomes lower than the second voltage VD2 at time T6. At this time, the power storage device 4 ends the voltage control of the DC power line 6 and resumes the charge / discharge power control commanded by the power supply equipment control unit 7. Then, the voltage VD of the DC power line 6 is controlled to the first voltage VD1 by the voltage control of the AC / DC inverter 5.

[0107] At time T when a new command is received from the power supply equipment control unit 7, the voltage VD of the DC power line 6 is the first voltage VD1. At this time, the upper limit of the converted power P5 of the AC / DC inverter 5 is updated to the minimum of the rated power P5 of the AC / DC inverter 5 and the converted power upper limit value received from the power supply equipment control unit 7 at time T. Furthermore, the lower limit of the converted power P5 of the AC / DC inverter 5 becomes the maximum of the rated power of the AC / DC inverter 5 × (-1) and the converted power lower limit value commanded from the power supply equipment control unit 7. The power storage device 4 operates in accordance with the charge / discharge power command or the charge / discharge current command received from the power supply equipment control unit 7 at time T. Furthermore, the charge / discharge power upper and lower limit values ​​or the charge / discharge current upper and lower limit values ​​and the SOC upper and lower limit values ​​are updated.

[0108] As described above, when setting voltage control switching priorities for the power storage devices in a configuration in which a plurality of power storage devices are connected to the DC power line 6, the voltage VD of the DC power line 6 can be controlled by setting the second voltage in the first and second embodiments as the second voltage VD2, the second voltage VD2A, ... for each power storage device.

[0109] Furthermore, in a configuration in which three or more power storage devices are connected, it is also possible to set voltage control switching priorities for a group of power storage devices that perform droop control and for each power storage device that does not perform droop control.

[0110] For example, when the power storage device 4, the power storage device 4A, the power storage device 4B, and the power storage device 4C are connected to the DC power line 6, it can be set so that the power storage device 4 and the power storage device 4A perform droop control, but the power storage device 4B and the power storage device 4C do not. In this case, the voltages at which the droop control of the power storage device 4 and the power storage device 4A starts are set to the second voltage VD2 and the fourth voltage VD4, and the voltages at which the power storage devices 4B and 4C start voltage control of the DC power line 6 are set to the second voltage VD2B and the fourth voltage VD4B, and the second voltage VD2C and the fourth voltage VD4C, respectively.

[0111] The magnitude relationship between the second voltage VD2, the second voltage VD2B, and the second voltage VD2C and the magnitude relationship between the fourth voltage VD4, the fourth voltage VD4B, and the fourth voltage VD4C can be set independently and arbitrarily. However, the maximum values ​​of the second voltage VD2, the second voltage VD2B, and the second voltage VD2C are set to be less than the third voltage VD3, and the minimum values ​​are set to be higher than the first voltage VD1. Furthermore, the maximum values ​​of the fourth voltage VD4, the fourth voltage VD4B, and the fourth voltage VD4C are set to be less than the first voltage VD1, and the minimum values ​​of the fourth voltage VD4, the fourth voltage VD4B, and the fourth voltage VD4C are set to be higher than the minimum DC voltage.

[0112] In this embodiment, the power storage device 4 and the power storage device 4A can be replaced with the configurations of the electric vehicle connection unit 611 and the electric vehicle 11 shown in FIG. 7 of the first embodiment, respectively. [Example]

[0113] 13 shows an example of the configuration of a power supply facility according to a fourth embodiment of the present invention. In this embodiment, one end (called the primary side) of a second DC / DC converter 60 is connected to a first DC power line 61 that connects a first DC / DC converter 3 and an AC / DC inverter 5. Then, a second DC power line 62 is connected to the other end (called the secondary side) of the second DC / DC converter 60.

[0114] That is, the second DC / DC converter 60 divides the DC power line 6 in the example configuration of the power supply facility in Example 1. The second DC / DC converter 60 is a bidirectional converter, and can charge the power storage device 4 with power generated by the solar cell 2 or power from the AC power supply 9 received via the AC / DC inverter 5, and can supply the power of the power storage device 4 to the load 10 via the AC / DC inverter 5.

[0115] Depending on the configuration of the solar cell 2, the output voltage of the first DC / DC converter 3 may be high (for example, 1000 V), and therefore in the configurations described in Examples 1 to 3, the first voltage, which is the voltage control target value of the AC / DC inverter 5, is set to a high voltage (for example, 1000 V), which results in the need to increase the withstand voltage of the power storage device 4. However, by installing the second DC / DC converter 60 and stepping down the output voltage (primary side voltage) of the first DC / DC converter 3, it is possible to prevent the withstand voltage of the power storage device 4 from becoming too high.

[0116] Furthermore, by configuring the second DC / DC converter 60 as an insulated bidirectional converter, it is possible to insulate the first DC / DC converter 3 from the power storage device 4. As a result, even if the second DC power line 62 deteriorates and a conductor portion is exposed and a human body touches it, no current path is formed from the solar cell 2, which is the power source, to the human body, so electric shock can be prevented even if the first DC / DC converter 3 is a non-insulated type (for example, a step-up chopper circuit).

[0117] In this embodiment, the second DC / DC converter 60 always controls the ratio of the primary side voltage to the secondary side voltage V2 to a constant value N during operation. That is, (primary side voltage) = N × (secondary side voltage). Here, N = 20 / 7. The rated power of the second DC / DC converter 60 is equal to the rated power of the DC / DC converter 42 of the power storage device 4.

[0118] Due to the constant voltage ratio control by the second DC / DC converter 60 described above, when the voltage of the second DC power line 62 is the first voltage VD1 (350 V), the second voltage VD2 (370 V), the third voltage VD3 (390 V), or the fourth voltage VD4 (340 V) shown in the first embodiment, the primary side voltage of the second DC / DC converter 60, i.e., the voltage of the first DC power line 61, becomes the first voltage VD1′ (1000 V), the second voltage VD2′ (1057 V), the third voltage VD3′ (1114 V), or the fourth voltage VD4′ (971 V), respectively.

[0119] In this embodiment, the power storage device 4 operates in the same manner as in embodiment 1. That is, when the voltage value of the second DC power line 62 is equal to or higher than a second voltage that is higher than the first voltage, and when the voltage value is lower than a fourth voltage that is lower than the first voltage, the power storage device 4 performs voltage control of the second DC power line 62.

[0120] The voltage control target value of the AC / DC inverter 5 is set to a first voltage VD1', and the threshold voltage at which the first DC / DC converter 3 ends MPPT control and starts voltage control is set to a third voltage VD3'. When the AC / DC inverter 5 can control the voltage of the first DC power line 61 to the first voltage VD1', the voltage of the second DC power line 62 becomes the first voltage VD1.

[0121] As described in the first embodiment, the AC / DC inverter 5 may not be able to control the voltage of the first DC power line 61 to the first voltage VD1′ due to the upper and lower limits of the converted power, and the voltage may increase from the first voltage VD1′ to the second voltage VD2′ (1057 V) or decrease to the fourth voltage VD4′ (971 V). At this time, the voltage of the second DC power line 62 also increases or decreases in response to the increase or decrease in the voltage of the first DC power line 61. If the voltage of the first DC power line 61 increases to the second voltage VD2′, the voltage of the second DC power line 62 increases to the second voltage VD2, and the power storage device 4 starts controlling the voltage of the second DC power line 62. Even if the power storage device 4 executes voltage control, if the voltage of the second DC power line 62 increases and reaches the third voltage VD3, the voltage of the first DC power line 61 increases to the third voltage VD3'. At this time, the first DC / DC converter 3 ends the MPPT control and controls the voltage of the first DC power line 61.

[0122] As described above, the voltage control target value of the AC / DC inverter 5 is set to the first voltage VD1', the threshold voltage at which the first DC / DC converter 3 ends MPPT control and performs voltage control is set to the third voltage VD3', and other controls and operations are similar to those of Example 1, so that the configuration example of the power supply facility in this example can also achieve the same effects as those of Example 1. The same applies to Examples 2 and 3. [Example]

[0123] 14 shows an example of the configuration of a power supply facility according to a fifth embodiment of the present invention. In this embodiment, a first DC / DC converter 3, an AC / DC inverter 5, and a power storage device 4 are connected to a first DC power line 61, which is the primary side of a second DC / DC converter 60, and a power storage device 4A is connected to a second DC power line 62, which is the secondary side of the second DC / DC converter 60. That is, a power storage device is connected to each of the primary side and the secondary side of the second DC / DC converter 60. The rated power of the second DC / DC converter 60 is equal to the rated power of a DC / DC converter 422 included in the power storage device 4A.

[0124] The second DC / DC converter 60 performs constant voltage ratio control (N=20 / 7) in the same manner as in Example 4. That is, when the voltages of the second DC power line 62 are the first voltage VD1 (350 V), the second voltage VD2 (370 V), the third voltage VD3 (390 V), the fourth voltage VD4 (340 V), the second voltage VD2 (365 V), and the second voltage VD2A (375 V) shown in Example 3, the voltages of the first DC power line 61 are the first voltage VD1′ (1000 V), the second voltage VD2′ (1057 V), the third voltage VD3′ (1114 V), the fourth voltage VD4′ (971 V), the second voltage VD2′ (1043 V), and the second voltage VD2A′ (1071 V), respectively.

[0125] The voltage control target value of the AC / DC inverter 5 is set to the first voltage VD1', and the threshold voltage at which the first DC / DC converter 3 ends MPPT control and performs voltage control is set to the third voltage VD3'. Furthermore, the power storage device 4 sets the threshold voltages at which the charge / discharge power control commanded by the power supply equipment control unit 7 is stopped and voltage control of the first DC power line 61 is performed to the second voltage VD2' or the second voltage VD2' and the fourth voltage VD4'. Other controls and operations are similar to those of the third embodiment, so that the example configuration of the power supply equipment in this embodiment can also achieve the same effects as those of the third embodiment.

[0126] In this embodiment, the power storage device 4 and the power storage device 4A can be replaced with the configurations of the electric vehicle connection unit 611 and the electric vehicle 11 shown in FIG. 7 of the first embodiment, respectively. [Explanation of symbols]

[0127] 1…Power supply equipment 2...Solar cells (renewable energy source) 3...First DC / DC converter 4, 4A…Power storage device 5...AC / DC inverter 6…DC power line 7...Power supply equipment control section 8...Power distribution line 9…AC power supply 10...Load 12... Power receiving system side 13…AC output stop command 60...Second DC / DC converter 61...First DC power line 62...Second DC power line

Claims

1. A power supply facility including a first conversion device arranged between an AC power line and a DC power line to perform power conversion, a second conversion device arranged between the DC power line and a storage battery to perform power conversion, and a third conversion device arranged between the DC power line and a renewable energy power source to perform power conversion, a first conversion device controls a voltage of the DC power line to a first voltage, and a second conversion device controls a voltage of the DC power line to a second voltage when the first conversion device cannot control the voltage of the DC power line to the first voltage and the voltage of the DC power line exceeds a second voltage that is set higher than the first voltage; the first conversion device and the third conversion device are connected to one end of a fourth conversion device by a first DC power line, and the other end of the fourth conversion device is connected to the second conversion device via the first DC power line; the fourth conversion device controls a ratio of a voltage of the first DC power line to a voltage of the second DC power line to a constant value; the first conversion device controls a voltage of the first DC power line to a voltage value obtained by multiplying the first voltage by the constant value; the second conversion device controls the voltage of the second DC power line to the second voltage when the first conversion device is unable to control the voltage of the first DC power line to a voltage value obtained by multiplying the first voltage by the constant value and the voltage of the second DC power line exceeds the second voltage.

2. The power supply facility according to claim 1, the third conversion device controls the voltage of the DC power line to the third voltage when the voltage of the first DC power line exceeds a voltage value obtained by multiplying a third voltage by the constant value.

3. The power supply facility according to claim 2, The third conversion device controls the generated power output by the renewable energy power source using maximum power point tracking (MPPT) when the voltage of the first DC power line is equal to or lower than a voltage value obtained by multiplying the third voltage by the constant value.

4. The power supply facility according to claim 1, the fourth conversion device performs voltage control of the second DC power line when the voltage of the second DC power line falls below a fourth voltage that is lower than the first voltage.

5. The power supply facility according to any one of claims 1 to 4, a power storage device including a storage battery and a second conversion device that converts an output of the storage battery into power is connected to the first DC power line and the second DC power line; a power storage device connected to the first DC power line, when a voltage of the first DC power line exceeds a voltage value obtained by multiplying the second voltage by the constant value, performing voltage control of the first DC power line.

6. The power supply facility according to claim 5, the power storage device connected to the first DC power line performs voltage control of the first DC power line when the voltage of the first DC power line falls below a voltage value obtained by multiplying a fourth voltage lower than the first voltage by the constant value.

7. The power supply facility according to any one of claims 1 to 6, The power supply facility is characterized in that the storage battery is mounted on an electric vehicle.

8. The power supply facility according to any one of claims 1 to 7, a power supply facility comprising a plurality of power storage devices each including a storage battery and a second conversion device that converts the output of the storage battery into power, the power storage devices each being connected to the DC power line, and a threshold value for executing voltage control of the DC power line and for each of the power storage devices being set to stop a commanded charge / discharge power control.

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