Electric power system and electric equipment

Abstract

And adjusting the pulsating power component according to the action of a grid-connected inverter of the system. This power system is provided with: a DC link unit; and a system grid-connected inverter connected to the DC link unit and configured to be connectable to a single-phase AC power supply. The power conversion unit includes a downstream operation for converting AC power supplied from a single-phase AC power source into DC power and supplying the DC power to the DC link unit, and a reverse current operation for converting DC power supplied from the DC link unit into AC power and supplying the AC power to the single-phase AC power source. One or more DC power sources connected to the DC link unit and configured so as to be able to supply DC power to the DC link unit; a smoothing capacitor that is connected to the DC link unit and smoothes the DC voltage of the DC link unit; and one or more electrical devices that are connected to the DC link unit and consume the DC power supplied from the DC link unit, the electrical devices having a pulsating power adjustment function for adjusting a pulsating power component in accordance with the operation of the system grid-connected inverter and the voltage phase of the single-phase AC power source. The pulsating power component is a frequency component that is an integral multiple of two or more of the power supply frequency of the single-phase AC power supply, among DC power consumed by the electrical device.

Description

Technical Field

[0001] The present disclosure relates to power systems and electrical equipment. Background Art

[0002] For example, Patent Document 1 describes a power conversion device, which includes a capacitor, an inverter unit, and a control unit, wherein the inverter unit switches the input voltage and outputs it, and the capacitor is connected to either the input side or the output side of the inverter unit. The control unit includes a voltage control unit, a current control unit, and a pulsation compensation unit. The voltage control unit is input with a terminal voltage signal of the capacitor, and calculates and outputs a power command signal for making the terminal voltage signal correspond to a command value. The current control unit is input with a command signal, which is obtained as an error between a current command signal obtained based on the power command signal and a current detection signal. The inverter unit is given pulse width modulation control based on the command signal. The pulsation compensation unit is at the upstream stage of the current control unit, and eliminates the pulsation component in response to the pulsation component induced by the terminal voltage.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 11-308871 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] A known structure uses a grid-connected inverter to convert DC power from a DC power source such as a solar panel into AC power, allowing the remaining power after individual consumption to flow back into the power grid. The power system contains a pulsating power component with a frequency twice that of the power supply, necessitating reduction of this pulsating power component. Grid-connected inverters require technology to control this pulsating power component in both their forward (converting AC power to DC power) and their reverse (converting DC power to AC) operations.

[0008] The present disclosure aims to adjust the pulsating power component according to the operation of a grid-connected inverter.

[0009] Means for solving problems

[0010] A power system according to a first aspect includes: a DC link unit; a grid-connected inverter connected to the DC link unit and configured to be connectable to a single-phase AC power supply, the inverter being configured to perform forward flow operation for converting AC power supplied from the single-phase AC power supply into DC power and supplying the power to the DC link unit, and backward flow operation for converting DC power supplied from the DC link unit into AC power and supplying the power to the single-phase AC power supply; one or more DC power supplies connected to the DC link unit and configured to supply DC power to the DC link unit; a smoothing capacitor connected to the DC link unit for smoothing the DC voltage of the DC link unit; and one or more electrical devices connected to the DC link unit for consuming the DC power supplied from the DC link unit. In the power system, the electrical devices have a pulsating power adjustment function for adjusting a pulsating power component, which is a frequency component of the DC power consumed by the electrical devices and is an integer multiple of two or more of the power supply frequency of the single-phase AC power supply, based on the operation of the grid-connected inverter and the voltage phase of the single-phase AC power supply. Thereby, the pulsating power component can be adjusted according to the operation of the grid-connected inverter.

[0011] In the power system of the second aspect, in the power system of the first aspect, the grid-connected inverter is provided with a parallel-off operation that performs neither conversion from AC power to DC power nor conversion from DC power to AC power. The pulsating power adjustment function of the electrical equipment adjusts the pulsating power component to approach zero or does not adjust the pulsating power component when the grid-connected inverter performs the parallel-off operation. Thus, the pulsating power component can be adjusted according to the parallel-off operation of the grid-connected inverter.

[0012] In the power system according to the third aspect, in the power system according to the first aspect or the second aspect, the pulsating power adjustment function of the electrical device adjusts the pulsating power component in a manner that reduces a frequency component at twice the power supply frequency included in the pulsating power component of the DC power supplied from the DC link unit to the DC power supply or the smoothing capacitor. This makes it possible to adjust the pulsating power component generated in single-phase AC.

[0013] In the power system of the fourth aspect, in the power system of the first aspect or the second aspect, the pulsating power adjustment function of the electrical device adjusts the amplitude of a frequency component at twice the power supply frequency included in the pulsating power component, and the phase difference between the voltage of the single-phase AC power supply and the frequency component at twice the power supply frequency included in the pulsating power component. This facilitates adjustment of the pulsating power component.

[0014] According to a fifth aspect, in the power system according to any one of the first to fourth aspects, the pulsating power adjustment function of the electrical device has a first control mode. In this first control mode, when the grid-connected inverter performs a reverse flow operation to supply first DC power from the DC link unit to the grid-connected inverter, the pulsating power component is adjusted so that the DC power consumed by the electrical device approaches the DC power obtained by subtracting the first DC power from the DC power supplied by the DC power source. This eliminates the need to suppress the output of the DC power source.

[0015] According to a sixth aspect, in the power system according to any one of the first to fifth aspects, the pulsating power adjustment function of the electrical device has a second control mode. In this second control mode, when the grid-connected inverter performs a forward flow operation to supply second DC power from the grid-connected inverter to the DC link unit, the pulsating power component is adjusted so that the DC power consumed by the electrical device approaches the sum of the DC power supplied by the DC power supply and the second DC power. This eliminates the need to suppress the output of the DC power supply.

[0016] In the power system of the seventh aspect, in the power system of the first aspect, the pulsating power adjustment function of the electrical device includes: a first control mode for adjusting the pulsating power component so that the DC power consumed by the electrical device approaches the DC power obtained by subtracting the first DC power from the DC power supplied by the DC power source when the DC power supplied from the DC link unit to the grid-connected inverter is a first DC power; a second control mode for adjusting the pulsating power component so that the DC power consumed by the electrical device approaches the DC power obtained by subtracting the first DC power from the DC power supplied by the DC power source when the DC power supplied from the grid-connected inverter to the DC link unit is a second DC power; and a third control mode for adjusting the pulsating power component so that the pulsating power component approaches zero or does not adjust the pulsating power component. Thus, the pulsating power component can be adjusted according to the operation of the grid-connected inverter.

[0017] According to an eighth aspect, in the power system of the seventh aspect, the grid-connected inverter has a parallel-off operation that performs neither conversion from AC power to DC power nor conversion from DC power to AC power. Regarding the pulsating power adjustment function of the electrical equipment, when the grid-connected inverter is performing reverse power operation and the pulsating power component exceeds a predetermined threshold value, the first control mode is used; when the grid-connected inverter is performing reverse power operation and the pulsating power component is below the threshold value, the third control mode is used; when the grid-connected inverter is performing forward power operation and the pulsating power component exceeds the threshold value, the second control mode is used; when the grid-connected inverter is performing forward power operation and the pulsating power component is below the threshold value, the third control mode is used; and when the grid-connected inverter is performing parallel-off operation, the third control mode is used. This reduces pulsation in the power consumed by the electrical equipment.

[0018] According to a ninth aspect, in the power system of the seventh aspect, the grid-connected inverter has a parallel-off operation that performs neither conversion from AC to DC power nor conversion from DC to AC power. The pulsating power adjustment function of the electrical equipment operates in the first control mode when the grid-connected inverter is performing reverse power operation, in the second control mode when the grid-connected inverter is performing forward power operation, and in the third control mode when the grid-connected inverter is performing parallel-off operation. This reduces the capacity of the smoothing capacitor.

[0019] In the power system of the tenth aspect, in the power system of any one of the first to ninth aspects, the electrical equipment includes a rotating electrical machine, and the pulsating power component is adjusted by adjusting the rotation speed or torque of the rotating electrical machine.

[0020] According to an eleventh aspect, in the power system according to any one of the first to ninth aspects, the electrical equipment is a heat pump device including a heat pump circuit.

[0021] In the power system according to a twelfth aspect, in the power system according to any one of the first to eleventh aspects, the DC power supply is a solar cell device. This facilitates connection to the power system.

[0022] In the power system according to a thirteenth aspect, in the power system according to any one of the first to eleventh aspects, the DC power supply is a power storage device. This facilitates connection to the power system.

[0023] An electrical device according to a fourteenth aspect is an electrical device that consumes DC power supplied from a DC link unit and has a pulsating power adjustment function for adjusting a pulsating power component based on the operation of a grid-connected inverter and the voltage phase of a single-phase AC power supply. The grid-connected inverter is connected to the single-phase AC power supply and is capable of a forward flow operation for converting AC power supplied from the single-phase AC power supply into DC power and supplying the power to the DC link unit, and a reverse flow operation for converting DC power supplied from the DC link unit into AC power and supplying the power to the single-phase AC power supply. The pulsating power component is a frequency component of the DC power consumed by the electrical device that is an integer multiple of two or more of the power supply frequency of the single-phase AC power supply. Thus, the pulsating power component can be adjusted based on the operation of the grid-connected inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a diagram showing an example of a power system in this embodiment.

[0025] Figure 2 The following diagrams outline the energy flow during reverse and forward operation of a grid-connected inverter. (a) shows reverse operation, and (b) shows forward operation.

[0026] Figure 3 This table shows the pulsating power components absorbed by the smoothing capacitor and the pulsating power components consumed by the DC load.

[0027] Figure 4 1 and 2 are diagrams illustrating energy flows in control mode 1. (a) is the energy flow, (b) is the power of the grid-connected inverter, (c) is the power of the smoothing capacitor, and (d) is the power of the DC load.

[0028] Figure 5 1 and 2 are diagrams illustrating energy flows in control mode 2. (a) is the energy flow, (b) is the power of the grid-connected inverter, (c) is the power of the smoothing capacitor, and (d) is the power of the DC load.

[0029] Figure 6 3 are diagrams illustrating energy flows in control mode 3. (a) is the energy flow, (b) is the power of the grid-connected inverter, (c) is the power of the smoothing capacitor, and (d) is the power of the DC load.

[0030] Figure 7 1 and 2 are diagrams illustrating energy flows in control mode 4. (a) is the energy flow, (b) is the power of the grid-connected inverter, (c) is the power of the smoothing capacitor, and (d) is the power of the DC load.

[0031] Figure 8 1 and 2 are diagrams illustrating energy flows in control mode 5. (a) is the energy flow, and (b) is the power of the DC load.

[0032] Figure 9 This diagram illustrates the energy flow in a power system according to a modified example. (a) shows the energy flow, (b) shows the power of the grid-connected inverter, (c) shows the power of the smoothing capacitor, and (d) shows the power of the DC load bank.

[0033] Figure 10 This table shows the pulsating power components absorbed by the smoothing capacitor and the pulsating power components consumed by the DC load.

[0034] Figure 11 1 and 2 are diagrams illustrating energy flows in control mode 6. (a) is the energy flow, (b) is the power of the grid-connected inverter, (c) is the power of the smoothing capacitor, and (d) is the power of the DC load.

[0035] Figure 12 1 and 2 are diagrams illustrating energy flows in control mode 7. (a) is the energy flow, (b) is the power of the grid-connected inverter, (c) is the power of the smoothing capacitor, and (d) is the power of the DC load.

[0036] Figure 13 This is a diagram illustrating the phase relationship in control mode 6.

[0037] Figure 14 This is a diagram illustrating the phase relationship in control mode 7. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

[0039] [Power System 1]

[0040] Figure 1 This is a diagram showing an example of the power system 1 in this embodiment.

[0041] Power system 1 includes a grid-connected inverter 10, a DC link unit 20, a smoothing capacitor 30, a solar panel 40, a battery 50, and an air conditioner 60. Power system 1 is connected to a single-phase AC power supply 100. Single-phase AC power supply 100 constitutes the power system. In the figure, grid-connected inverter 10 is denoted as grid-connected INV. The grid-connected inverter 10, solar panel 40, battery 50, and air conditioner 60 included in power system 1 are referred to simply as devices. A DC link is sometimes denoted as a DC link. Solar panel 40 is an example of a solar cell device. Battery 50 is an example of a power storage device.

[0042] The grid-connected inverter 10 has two input and output units for inputting and outputting electric power. One input and output unit of the grid-connected inverter 10 is configured to be connectable to a single-phase AC power supply 100. The other input and output unit of the grid-connected inverter 10 is connected to a DC link unit 20. A smoothing capacitor 30 is connected to the DC link unit 20. A solar panel 40 is connected to the DC link unit 20 via a DC / DC converter 41. A battery 50 is connected to the DC link unit 20 via a DC / DC converter 51. An air conditioner 60 is connected to the DC link unit 20. The AC current path connected to the single-phase AC power supply 100 is an AC line (at Figure 1 The DC link unit 20, the solar panel 40, the battery 50 and the air conditioner 60 are connected to the DC current path as the DC line (in Figure 1 The grid-connected inverter 10 is provided between the AC line and the DC line.

[0043] The grid-connected inverter 10 performs forward-flow, reverse-flow, and parallel-splitting operations. In other words, the operations of the grid-connected inverter 10 in the present disclosure are forward-flow, reverse-flow, and parallel-splitting operations. The forward-flow operation converts AC power into DC power, supplying power from the single-phase AC power source 100 to the DC link unit 20. The reverse-flow operation converts DC power into AC power, supplying power from the DC link unit 20 to the single-phase AC power source 100. The grid-connected inverter 10 is an inverter capable of bidirectional power supply. In reverse-flow and forward-flow operations, the AC line side and the DC line side operate in parallel via the grid-connected inverter 10. Parallel-splitting operation is an operation that performs neither reverse-flow operation (converting DC power into AC power) nor forward-flow operation (converting AC power into DC power). In parallel-splitting operation, the AC line side and the DC line side operate separately. The grid-connected inverter 10 connects an AC power system (here, the power system) to a DC power system.

[0044] The grid-connected inverter 10 is configured by, for example, a full-bridge circuit in which four transistors are arranged in a bridge shape.

[0045] The DC link unit 20 is a DC current path. One of the two current paths is represented as positive (+) and the other as negative (-).

[0046] The smoothing capacitor 30 is connected between two current paths of the DC link unit 20 to smooth out ripples generated in the DC voltage. The smoothing capacitor 30 is, for example, an electrolytic capacitor.

[0047] The solar panel 40 converts light energy into electrical energy through the photoelectric effect. The DC / DC converter 41 is provided between the solar panel 40 and the DC link unit 20 to convert the DC voltage output by the solar panel 40 into the DC voltage of the DC link unit 20.

[0048] The battery 50 stores electric energy. The DC / DC converter 51 is provided between the battery 50 and the DC link unit 20 , and converts the output voltage of the battery 50 into a DC voltage for the DC link unit 20 .

[0049] The solar panel 40 and the battery 50 are examples of DC power supplies. The power system 1 only needs to include either the solar panel 40 or the battery 50. When describing the solar panel 40 and the battery 50 together, they are referred to as a DC power supply. A DC power supply is a device that can supply power unidirectionally, at least to the DC link 20. A DC power supply can also be a device that can supply power bidirectionally to the DC link 20.

[0050] The air conditioner 60 consumes DC power supplied from the DC link unit 20. A heat pump system may be substituted for the air conditioner 60. The air conditioner 60 and the heat pump system are examples of electrical devices that consume DC power. Electrical devices are loads that consume DC power. Electrical devices are devices that are supplied with power unidirectionally from the DC link unit 20. In other words, electrical devices do not supply power to the DC link unit 20. Electrical devices that consume DC power are sometimes referred to as electrical devices that are DC loads. The following description will refer to the air conditioner 60 as a DC load. Electrical devices that are DC loads, such as the air conditioner 60 and the heat pump system, will be described in detail later.

[0051] exist Figure 1 In , define the name of the power in each device and the direction of power supply. Figure 1 In FIG, the direction of power supply is indicated by arrows.

[0052] The power when the grid-connected inverter 10 performs either forward flow operation or reverse flow operation is expressed as power P pcs Sometimes the power P pcs It is expressed as DC power P pcs About Power P pcs The direction of power supplied from the DC link unit 20 to the single-phase AC power supply 100 is defined as positive (+). pcs It is positive (+) in reverse flow operation and negative (-) in forward flow operation. pcs It is zero ("0"). In addition, electric power is sometimes expressed as energy.

[0053] The power supplied to the smoothing capacitor 30 is expressed as power P C About Power P C The direction of supply from the positive (+) side to the negative (-) side of the DC link unit 20 is referred to as positive (+).

[0054] The power supplied by the solar panel 40 is expressed as power P pv About Power P pv The direction of power supplied from the solar panel 40 to the DC link unit 20 is defined as positive (+).

[0055] The power supplied by the battery 50 is expressed as power P battery About Power P battery The direction of power supply from the battery 50 to the DC link unit 20 is set to positive (+). battery If it is positive (+), the battery 50 is discharged, and if it is negative (-), the battery 50 is charged.

[0056] The power consumed by the air conditioner 60 is expressed as power P load About Power P load The direction of supply from the DC link unit 20 to the air conditioner 60 is defined as positive (+).

[0057] The power P of the system grid-connected inverter 10 pcs It is expressed as formula (1). Here, P pcs_amp It is the power P pcs ω is the amplitude of ω, and ω is the power supply frequency (angular frequency) of the single-phase AC power supply 100. Hereinafter, the power supply frequency (angular frequency) will be referred to as frequency.

[0058] As shown in equation (1), when the grid-connected inverter 10 performs either forward flow operation or reverse flow operation, −P pcs_ac The power pulsation with a frequency 2ω, which is twice the frequency ω of the single-phase AC power supply 100, is represented by cos(2ωt). pcs_ac is the pulsating power generated in the grid-connected inverter 10. In other words, the power P pcs Power P containing AC components pcs_ac and the DC component of the power P pcs_dc . Below, the power P pcs_ac The pulsating power component P pcs_ac , the power P pcs_dc It is expressed as the DC power component P pcs_dc .

[0059] [Mathematical formula 1]

[0060]

[0061] here,

[0062] If power pulsation occurs in the DC link unit 20, it can degrade the battery 50 or reduce the power generated by the solar panel 40. The following description assumes that the power pulsation has a frequency 2ω that is twice that of the single-phase AC power supply 100. However, the power pulsation may also have a frequency component that is an integer multiple of 2 or more of the single-phase AC power supply 100.

[0063] The energy balance makes equation (2) valid. Equation (2') is obtained by rewriting equation (2).

[0064] [Mathematical formula 2]

[0065] P pv +P battery -P load -P C =P pcs ····(2)

[0066] P pcs –P pv -P battery +P load +P C =0····(2′)

[0067] The power P of the solar panel 40 pv It is only the DC component, expressed as formula (3). In other words, the power P pv Power P containing DC components pv_dc Next, the DC component power P pv_dc It is expressed as the DC power component P pv_dc . DC power component P pv_dc Determined by MPPT (Maximum Power Point Control) control.

[0068] The power P of the battery 50 battery It is only the DC component, which is expressed by formula (4). In other words, the power P battery Power P containing DC components battery_dc Next, the DC component power P battery_dc It is expressed as the DC power component P battery_dc . DC power component P battery_dc Determined by the energy balance of the power system 1.

[0069] Power P of the air conditioner 60 load It is expressed as formula (5). Power P load The power P includes an AC component having a frequency 2ω twice that of the single-phase AC power supply 100. load_acand the DC component of the power P load_dc . Below, the AC component power P load_ac It is expressed as AC power component P load_ac , the DC component of the power P load_dc It is expressed as the DC power component P load_dc AC power component P load_ac It is used to eliminate the pulsating power component P generated by the forward and reverse flow actions of the grid-connected inverter 10. pcs_ac Control of DC power component P load_dc The required air conditioning capacity is determined by the AC power component P consumed by the air conditioner 60. load_ac Adjusted to be close to the pulsating power component P generated in the grid-connected inverter 10 pcs_ac , it is possible to eliminate the pulsating power component generated in the grid-connected inverter 10. load_ac The pulsating power component P load_ac .

[0070] [Mathematical formula 3]

[0071] P pv =P pv_dc (P pv ≥0)····(3)

[0072] P battery =P battery_dc ····(4)

[0073] P load =P load_ac cos(2ωt)+P load_dc (P load ≥0)····(5)

[0074] Figure 2 This is a diagram for explaining an overview of energy flows in the reverse flow operation and the forward flow operation of the grid-connected inverter 10 . Figure 2 (a) is the counter-current action, Figure 2 (b) is the action in the direction of the current. Figure 2 In (a) and (b), the solid lines with arrows represent the flow of DC power (DC power component in the figure), and the dotted lines with arrows represent the flow of AC power (AC power component in the figure).

[0075] exist Figure 2 In the reverse power flow operation shown in (a), the grid-connected inverter 10 converts DC power into AC power and supplies power P from the DC link unit 20 to the single-phase AC power supply 100. pcsThe power Pcos of the DC power P supplied from the solar panel 40 and the battery 50 is 2 (ωt) is consumed by the air conditioner 60, and the remaining power Psin 2 (ωt) is supplied from the grid-connected inverter 10 to the single-phase AC power source 100. During reverse power operation, the DC load splits the DC power into two AC components, causing the power consumed by the DC load to pulsate, thereby eliminating the power pulsation caused by the grid-connected inverter 10.

[0076] exist Figure 2 In the downstream operation shown in (b), the grid-connected inverter 10 converts AC power into DC power and supplies power from the single-phase AC power source 100 to the DC link unit 20. The air conditioner 60 consumes the DC power P supplied by the solar panel 40. pv The DC power P supplied by the battery 50 battery The sum is the DC power P pv +P battery In addition, the air conditioner 60 consumes the pulsating power Psin supplied from the grid-connected inverter 10. 2 (ωt). In the downstream operation, the pulsating power in the DC link unit 20 is directly passed to the DC load. The DC load consumes the pulsating power Psin 2 (ωt), thereby eliminating the pulsation of power caused by the grid-connected inverter 10.

[0077] exist Figure 2 In either the reverse flow operation or the forward flow operation shown in (a) or (b), the pulsating power generated in the grid-connected inverter 10 is consumed by the air conditioner 60, thereby suppressing the pulsating power from reaching the DC power supply such as the solar panel 40 and the battery 50.

[0078] In the power system 1 of the present disclosure, the power consumed by electrical equipment such as the air conditioner 60 is pulsated according to the operation of the grid-connected inverter 10, thereby eliminating the pulsation of the power generated in the grid-connected inverter 10. The electrical equipment has a pulsating power adjustment function for adjusting the pulsating power. In the case where the electrical equipment does not have a pulsating power adjustment function, a large-capacity smoothing capacitor 30 is required to suppress the pulsation of the power. In the power system 1 of the present disclosure, the pulsation of the power generated in the grid-connected inverter 10 is eliminated by using the pulsating power adjustment function of the electrical equipment that consumes DC power, thereby reducing the capacity of the smoothing capacitor 30.

[0079] (Example 1)

[0080] In the first embodiment, the smoothing capacitor 30 absorbs as much of the pulsating power component of the double frequency 2ω of the single-phase AC power supply 100 as possible, and the DC load (here, the air conditioner 60) absorbs the part that cannot be absorbed by the smoothing capacitor 30.

[0081] The power P of the smoothing capacitor 30 C The power P of the smoothing capacitor 30 is expressed as follows: C The power P includes an AC component having a frequency 2ω twice that of the single-phase AC power supply 100. C_ac and the DC component of the power P C_dc AC component power P C_ac The pulsating power component is absorbed by the smoothing capacitor 30. C_ac The pulsating power component P is expressed as C_ac The pulsating power component P C_ac The absolute value of |P C_ac The maximum value of | is set as the maximum pulsating power component P C100 (P C100 >0). Maximum pulsating power component P C100 is the pulsating power component P that the smoothing capacitor 30 can absorb C_ac The maximum value of the maximum pulsating power component P C100 This is an example of a prescribed threshold value.

[0082] [Formula 4]

[0083] P c =P C_ac cos(2ωt)+P C_dc ····(6)

[0084] According to the power P of the system grid-connected inverter 10 pcs The pulsating power component P in pcs_ac and the maximum pulsating power component P C100 The relationship between the pulsating power component P consumed by the air conditioner 60 is determined load_ac .

[0085] Figure 3 This is to explain the pulsating power component P absorbed by the smoothing capacitor 30. C_ac and the pulsating power component P consumed by the DC load (here, the air conditioner 60) load_ac The table is based on the pulsating power component P in the system grid-connected inverter 10. pcs_ac and the maximum pulsating power component P C100 The relationship between the pulsating power component P is classified. pcs_ac Expressed by absolute value.

[0086] The operation of the grid-connected inverter 10 is a forward flow operation in control modes 1 and 2, a reverse flow operation in control modes 3 and 4, and a parallel-off operation in control mode 5. In the forward flow operation, the pulsating power component P pcs_ac Negative (P pcs_ac <0), in reverse flow operation, the pulsating power component P pcs_ac is positive (P pcs_ac >0), in the splitting action, the pulsating power component P pcs_ac and DC power component P pcs_dc is zero (“0”)(P pcs_ac =0,P pcs_dc =0).

[0087] Control mode 1 is the flow-following action, which is the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 When(|P pcs_ac |>P C100 ). At this time, even if the smoothing capacitor 30 absorbs the pulsating power component P pcs_ac The maximum pulsating power component P in C100 A considerable amount of pulsating power component P pcs_ac There is still a residual power component exceeding the maximum pulsating power P C100 The pulsating power component (|P pcs_ac |-P C100 The DC load consumes the residual pulsating power component (|P pcs_ac |-P C100 ).

[0088] Control mode 2 is the flow-following action, which is the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 When the following (P C100 ≥|P pcs_ac |>0). At this time, the pulsating power component P pcs_ac The maximum pulsating power component P of the smoothing capacitor 30 is C100 Absorption. DC load does not need to consume the pulsating power component P pcs_ac (P load_ac =0).

[0089] Control mode 3 is reverse flow operation, which is the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 When the following (P C100 ≥|P pcs_ac |>0). At this time, the pulsating power component P pcs_ac The maximum pulsating power component P of the smoothing capacitor 30 is C100Absorption. DC load does not need to consume pulsating power components (P load_ac =0).

[0090] Control mode 4 is reverse flow operation, which is the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 When(|P pcs_ac |>P C100 ). At this time, even if the smoothing capacitor 30 absorbs the pulsating power component P pcs_ac The maximum pulsating power component P in C100 A considerable amount of pulsating power component P pcs_ac There is still a residual power component exceeding the maximum pulsating power P C100 The pulsating power component (|P pcs_ac |-P C100 The DC load consumes the residual pulsating power component (|P pcs_ac |-P C100 ).

[0091] Control mode 5 is the parallel-off operation, the power P of the grid-connected inverter 10 is pcs is zero (“0”)(P pcs_ac =0,P pcs_dc = 0). The grid-connected inverter 10 does not generate pulsating power components. The pulsating power components P absorbed by the smoothing capacitor 30 are C_ac And the pulsating power component P consumed by the DC load load_ac is zero (“0”)(P C_ac =0,P load_ac =0).

[0092] As mentioned above, it is divided into pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 When, and the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 Below. It can also be divided into pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 When the above, and the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 hour.

[0093] Hereinafter, control modes 1 to 5 will be described using an energy flow diagram.

[0094] Figure 4 This is a diagram illustrating the energy flow in control mode 1. Figure 4 (a) is the energy flow, Figure 4 (b) is the power P of the grid-connected inverter 10 pcs , Figure 4 (c) is the power P of the smoothing capacitor 30 C , Figure 4 (d) is the power P of the DC load (here, the air conditioner 60) load .exist Figure 4 In (b) to (d), the horizontal axis is time t. Figure 4 (b) to (d) show one cycle of the single-phase AC power supply 100. Figure 4 In (a), the solid lines with arrows represent the flow of direct current (DC) power, and the dashed lines with arrows represent the flow of alternating current (AC) power. The flow of AC power is the flow of the pulsating power component. In the other figures shown below, descriptions of the same parts are omitted.

[0095] Control mode 1 is the flow-following action, which is the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 When(|P pcs_ac |>P C100 ). At this time, the smoothing capacitor 30 absorbs the pulsating power component P pcs_ac The maximum pulsating power component P in C100 The air conditioner 60 consumes a considerable amount of the remaining pulsating power component (|P pcs_ac |-P C100 )( Figure 4 Furthermore, the air conditioner 60 consumes the power P from the solar panel 40. pv and the power P from the battery 50 battery The sum (P pv +P battery ), and the DC power component P supplied from the grid-connected inverter 10 to the DC link unit 20 pcs_dc The power P from the solar panel 40 pv and the power P from the battery 50 battery The sum (P pv +P battery ) is the DC power supplied by the DC power supply. The DC power (-P pcs ) is an example of the second DC power.

[0096] In control mode 1, the pulsating power adjustment function of the electrical device (here, the air conditioner 60) as a DC load adjusts the pulsating power component so that the DC power consumed by the electrical device approaches the sum of the DC power supplied by the DC power supply and the second DC power. Control mode 1 is an example of the second control mode. In addition, the pulsating power adjustment function of this embodiment includes a pulsating power component acquisition unit that acquires the pulsating power component P pcs_ac and a pulsating power phase acquisition unit that acquires the phase 2ωt of the pulsating power component of the double frequency 2ω of the single-phase AC power supply 100. The pulsating power component acquisition unit may be configured to, for example, acquire the power P measured by the power measuring unit. pcs The pulsating power component acquisition unit may be configured to acquire the calculated value of the grid-connected inverter 10. The pulsating power phase acquisition unit may be configured to acquire the power P measured by the power measuring unit. pcs The pulsating power phase acquisition unit may be configured to detect the voltage phase ωt of the grid-connected inverter 10 detected by a voltage phase detection unit such as a phase synchronization circuit or a zero-crossing circuit. The pulsating power phase acquisition unit may be configured to acquire a calculated value of the grid-connected inverter 10. Furthermore, the pulsating power phase acquisition unit may be configured to acquire the phase 2ωt or the cosine value cos(2ωt) of the phase 2ωt.

[0097] Figure 5 This is a diagram illustrating the energy flow in control mode 2. Figure 5 (a) is the energy flow, Figure 5 (b) is the power P of the grid-connected inverter 10 pcs , Figure 5 (c) is the power P of the smoothing capacitor 30 C , Figure 5 (d) is the power P of the DC load (here, the air conditioner 60) load .

[0098] Control mode 2 is the flow-following action, which is the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 When the following (P C100 ≥|P pcs_ac |>0). At this time, the pulsating power component P pcs_ac The maximum pulsating power component P of the smoothing capacitor 30 is C100 The air conditioner 60 does not need to consume the pulsating power component P pcs_ac (P load_ac =0). The power consumed by the air conditioner 60 P loadOnly the DC power component P load_dc (Refer to Figure 5 (d)) The DC power component P consumed by the air conditioner 60 load_dc is the power P from the solar panel 40 pv and the power P from the battery 50 battery The sum (P pv +P battery ), and the DC power component P supplied from the grid-connected inverter 10 pcs_dc .

[0099] In control mode 2, the pulsating power adjustment function of the electrical device (here, the air conditioner 60) serving as the DC load is adjusted so that the pulsating power component approaches zero ("0"), or the pulsating power component is not adjusted. Control mode 2 is an example of the third control mode.

[0100] Figure 6 This is a diagram explaining the energy flow in control mode 3. Figure 6 (a) is the energy flow, Figure 6 (b) is the power P of the grid-connected inverter 10 pcs , Figure 6 (c) is the power P of the smoothing capacitor 30 C , Figure 6 (d) is the power P of the DC load (here, the air conditioner 60) load .

[0101] Control mode 3 is reverse flow operation, which is the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P C100 When the following (P C100 ≥|P pcs_ac |>0). At this time, the pulsating power component P pcs_ac The maximum pulsating power component P of the smoothing capacitor 30 is C100 Absorption. The air conditioner 60 does not need to consume the pulsating power component (P load_ac =0). The power consumed by the air conditioner 60 P load Only the DC power component P load_dc (Refer to Figure 6 (d)) The DC power component P consumed by the air conditioner 60 load_dc The power P from the solar panel 40 pv and the power P from the battery 50 battery The sum (P pv +P battery )supply.

[0102] In control mode 3, the pulsating power adjustment function of the electrical equipment (here, air conditioner 60) serving as a DC load can be adjusted to bring the pulsating power component close to zero ("0"), or the pulsating power component can be left unadjusted. Control mode 3 is an example of the third control mode.

[0103] Figure 7 This is a diagram explaining the energy flow in control mode 4. Figure 7 (a) is the energy flow, Figure 7 (b) is the power P of the grid-connected inverter 10 pcs , Figure 7 (c) is the power P of the smoothing capacitor 30 C , Figure 7 (d) is the power P of the DC load (here, the air conditioner 60) load .

[0104] Control mode 4 is reverse flow action, which is power P pcs_ac The absolute value of the maximum pulsating power component P C100 When(|P pcs_ac |>P C100 In reverse power operation, the grid-connected inverter 10 converts DC power into AC power and supplies power P from the DC link unit 20 to the single-phase AC power supply 100. pcs At this time, the smoothing capacitor 30 absorbs the pulsating power component P pcs_ac The maximum pulsating power component P in C100 The air conditioner 60 consumes a considerable amount of the remaining pulsating power component (|P pcs_ac |-P C100 )( Figure 7 The AC power component is shown by the dotted arrow in FIG. 1 ). The air conditioner 60 consumes the power P from the solar panel 40. pv and the power P from the battery 50 battery The sum (P pv +P battery ) minus the DC power component P supplied from the DC link unit 20 to the grid-connected inverter 10 pcs_dc The DC power P supplied from the DC link unit 20 to the grid-connected inverter 10 is pcs This is an example of the first DC power.

[0105] In control mode 4, the pulsating power adjustment function of the electrical device (here, the air conditioner 60) serving as a DC load adjusts the pulsating power component so that the DC power consumed by the electrical device approaches the power obtained by subtracting the first DC power from the DC power supplied by the DC power supply. Control mode 4 is an example of the first control mode.

[0106] Figure 8 This is a diagram explaining the energy flow in control mode 5. Figure 8 (a) is the energy flow, Figure 8 (b) is the power P of the DC load (here, the air conditioner 60) load .

[0107] Control mode 5 is the parallel-off operation, the power P of the grid-connected inverter 10 is pcs is zero (“0”)(P pcs =0). The pulsating power component P consumed by the air conditioner 60 load_ac The air conditioner 60 consumes the power P from the solar panel 40. pv and the power P from the battery 50 battery The sum (P pv +P battery ) of electricity.

[0108] In control mode 5, the pulsating power adjustment function of the electrical device (here, the air conditioner 60) serving as a DC load is adjusted so that the pulsating power component approaches zero ("0"), or the pulsating power component is not adjusted. Control mode 5 is an example of the third control mode.

[0109] (Variation of Example 1)

[0110] In the first embodiment, one air conditioner 60 is used as a DC load. In a modified example, a plurality of DC loads are provided.

[0111] Figure 9 It is a diagram illustrating the energy flow in the power system 2 according to a modification. Figure 9 (a) is the energy flow, Figure 9 (b) is the power P of the grid-connected inverter 10 pcs , Figure 9 (c) is the power P of the smoothing capacitor 30 C , Figure 9 (d) is the power P of the DC load group (here, air conditioners 60 and 61) load . Figure 9 yes Figure 7 Control mode 4 shown.

[0112] The power system 2 includes an air conditioner 61 in addition to the air conditioner 60. The air conditioner 61 is connected to the DC link unit 20 in parallel with the air conditioner 60. The air conditioner 60 and the air conditioner 61 constitute a DC load group. Figure 1 The power system 1 shown is the same, and therefore the same reference numerals are used and description thereof is omitted.

[0113] In the power system 2, the power P is controlled by the DC load group composed of the air conditioner 60 and the air conditioner 61.load Of course, in a DC load group, the pulsating power component may be consumed by only one unit, or the pulsating power component may be consumed by multiple units.

[0114] (Example 2)

[0115] In the power system 1 of Example 1, the pulsating power component of twice the frequency 2ω of the single-phase AC power source 100 is absorbed by the smoothing capacitor 30, while the unabsorbed portion is consumed by the DC load (here, the air conditioner 60). In the power system 3 of Example 2, the pulsating power component is consumed by the DC load, while the unabsorbed portion is absorbed by the smoothing capacitor 30. Example 2 swaps the roles of the smoothing capacitor 30 and the DC load in Example 1.

[0116] In the power system 3, as an example, the maximum value of the pulsating power component that can be consumed by the DC load (here, the air conditioner 60) is set to the DC power component P load_dc 1 / 2 of the maximum pulsating power component P load_dc If the maximum value is increased, the power supplied to the DC load will fluctuate drastically, which may affect the air conditioning performance.

[0117] Figure 10 This is to explain the pulsating power component P absorbed by the smoothing capacitor 30. C_ac and the pulsating power component P consumed by the DC load (here, the air conditioner 60) load_ac In this table, the pulsating power component P in the system grid-connected inverter 10 is pcs_ac and the maximum pulsating power component P load_dc / 2 to classify the relationship between them. Figure 10 It will Figure 3 The pulsating power component P absorbed by the smoothing capacitor 30 in C_ac The pulsating power component P consumed by the DC load (here, the air conditioner 60) load_ac Replace, and then the maximum pulsating power component P C100 Replaced by the maximum pulsating power component P load_dc / 2 and the resulting graph.

[0118] Figure 10 In the equation, the pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P load_dc / 2 and pulsating power component P pcs_ac The absolute value of the maximum pulsating power component P load_dc / 2 or less. It can also be divided into pulsating power components P pcs_ac The absolute value of the maximum pulsating power component P load_dc / 2 or more and the pulsating power component P pcs_acThe absolute value of the maximum pulsating power component P load_dc / 2 o'clock.

[0119] Figure 10 The energy flow of control mode 1 is Figure 4 Since the control mode 1 of the embodiment 1 shown is the same, it is indicated as control mode 1. Figure 10 The energy flow of control mode 4 is Figure 7 The control mode 4 of the embodiment 1 shown is the same and is therefore referred to as control mode 4. Figure 10 The energy flow of control mode 5 is Figure 8 Since the control mode 5 of the embodiment 1 shown is the same, it is indicated as control mode 5.

[0120] Figure 11 This is a diagram explaining the energy flow in control mode 6. Figure 11 (a) is the energy flow, Figure 11 (b) is the power P of the grid-connected inverter 10 pcs , Figure 11 (c) is the power P of the smoothing capacitor 30 C , Figure 11 (d) is the power P of the DC load (here, the air conditioner 60) load .

[0121] Control mode 6 is the flow-following action, the pulsating power component P of the grid-connected inverter 10 is pcs_ac The absolute value of the maximum pulsating power component P that the air conditioner 60 can consume is load_dc / 2 or less (P load_dc / 2≥|P pcs_ac |>0). At this time, the pulsating power component P pcs_ac All of it is consumed by the air conditioner 60. The smoothing capacitor 30 does not need to absorb the pulsating power component. Figure 11 The flow path of the pulsating power component in the energy flow shown in (a) is Figure 5 (a) shows a different control mode 3. Figure 5 In (a), the pulsating power component is supplied from the grid-connected inverter 10 to the smoothing capacitor 30. Figure 11 In (a), the pulsating power component is supplied from the grid-connected inverter 10 to the air conditioner 60. The air conditioner 60 consumes the power P from the solar panel 40. pv and the power P from the battery 50 battery The sum (P pv +P battery ), and the DC power component P supplied from the grid-connected inverter 10 to the DC link unit 20 pcs_dc .

[0122] In control mode 6, the pulsating power adjustment function of the electrical device (here, air conditioner 60) serving as a DC load adjusts the pulsating power component so that the DC power consumed by the electrical device approaches the sum of the DC power supplied by the DC power source and the second DC power. Control mode 6 is an example of the second control mode.

[0123] Figure 12 This is a diagram explaining the energy flow in control mode 7. Figure 12 (a) is the energy flow, Figure 12 (b) is the power P of the grid-connected inverter 10 pcs , Figure 12 (c) is the power P of the smoothing capacitor 30 C , Figure 12 (d) is the power P of the DC load (here, the air conditioner 60) load .

[0124] Control mode 7 is reverse flow action, which is power P pcs_ac The absolute value of the maximum pulsating power component P that the air conditioner 60 can consume is load_dc / 2 or less (P load_dc / 2≥|P pcs_ac |>0). At this time, the pulsating power component P pcs_ac All of it is consumed by the air conditioner 60. The smoothing capacitor 30 does not need to absorb the pulsating power component. Figure 12 The flow path of the pulsating power component in the energy flow shown in (a) is Figure 6 (a) shows a different control mode 3. Figure 6 In (a), the pulsating power component P pcs_ac The power is supplied from the smoothing capacitor 30 to the grid-connected inverter 10. Figure 12 In (a), the pulsating power component P pcs_ac The air conditioner 60 supplies the power to the grid-connected inverter 10. The air conditioner 60 consumes the power P from the solar panel 40. pv and the power P from the battery 50 battery The sum (P pv +P battery ) minus the DC power component P supplied from the DC link unit 20 to the grid-connected inverter 10 pcs_dc The DC power obtained.

[0125] In control mode 7, the pulsating power adjustment function of the electrical device (here, air conditioner 60) serving as a DC load adjusts the pulsating power component so that the DC power consumed by the electrical device approaches the DC power difference obtained by subtracting the first DC power from the DC power supplied by the DC power supply. Control mode 7 is an example of the first control mode.

[0126] In the second embodiment, as in the modified example of the first embodiment, a plurality of DC loads may be provided.

[0127] Next, in control mode 6 (refer to Figure 10 and Figure 11 ) and control mode 7 (refer to Figure 10 and Figure 12 ), the relationship between the voltage phase ωt of the single-phase AC power supply 100 and the phase 2ωt of the pulsating power component of twice the frequency 2ω of the single-phase AC power supply 100 is described.

[0128] Figure 13 is a diagram illustrating the phase relationship in control mode 6. Figure 13 In FIG. 1 , the voltage waveform of the single-phase AC power supply 100 and the power P of the grid-connected inverter 10 are shown from top to bottom. pcs Waveform, power P of the air conditioner 60 as a DC load load Waveform, power P of solar panel 40 pv Waveform, and the power P of the battery 50 battery The horizontal axis represents the phase (degrees) of the voltage of the single-phase AC power supply 100 . Figure 13 1 shows one cycle of the voltage of the single-phase AC power supply 100. The vertical axis represents power (W), and the axis indicated by the arrow represents zero ("0") of power.

[0129] exist Figure 13 , the case where the power factor is 1 is shown. The phase difference between the voltage and the current of the single-phase AC power supply 100 is 0 degrees or 180 degrees. The phase difference between the voltage and the current varies depending on the power factor.

[0130] Control mode 6 is the flow-following action, power P pcs Negative (-)(P pcs <0). Voltage and power P pcs The phase difference between the pulsations generated in the circuit is 135 degrees. s |sin(ωt), at the power P pcs The pulsation generated in |P pcs_ac |sin(2(ωt-135 degrees)). In control mode 6, the pulsating power component P pcs_ac All are consumed by the air conditioner 60. The power waveform of the air conditioner 60 is to eliminate the power P pcs The pulsation mode in the power supply can be pulsated with a phase difference of 45 degrees relative to the voltage. The pulsation power adjustment function of the air conditioner 60 is adjusted so that the phase difference with the voltage is close to 45 degrees. load In other words, the pulsating power adjustment function of the air conditioner 60 is based on the voltage |Es |sin(ωt) approaches |P load_ac |Adjust the power P by sin(2(ωt-45 degrees)) load The pulsating power component of the solar panel 40 is pv The power P of the battery 50 battery The sum is constant and is not affected by power pulsations.

[0131] Figure 14 is a diagram illustrating the phase relationship in control mode 7. Figure 14 In FIG. 1 , the voltage waveform of the single-phase AC power supply 100 and the power P of the grid-connected inverter 10 are shown from top to bottom. pcs Waveform, power P of the air conditioner 60 as a DC load load Waveform, power P of solar panel 40 pv Waveform, and the power P of the battery 50 battery The horizontal axis represents the phase (degrees) of the voltage of the single-phase AC power supply 100. Figure 14 1 shows one cycle of the voltage of the single-phase AC power supply 100. The vertical axis is power (W), and the axis indicated by the arrow is zero ("0") of power. Figure 14 In, with Figure 13 Similarly, the case where the power factor is 1 is shown.

[0132] Control mode 7 is reverse flow action, power P pcs Positive (+)(P pcs >0). Voltage and power P pcs The phase difference between the pulsations generated in the circuit is 45 degrees. s |sin(ωt), at the power P pcs The pulsation generated in |P pcs_ac |sin(2(ωt-45 degrees)). In control mode 7, the pulsating power component P pcs_ac All are consumed by the air conditioner 60. The power waveform of the air conditioner 60 is used to eliminate the power P The pulsation in pcs can be pulsated with a phase difference of 135 degrees relative to the voltage. The pulsation power adjustment function of the air conditioner 60 is adjusted so that the phase difference with the voltage is close to 135 degrees. load In other words, the pulsating power adjustment function of the air conditioner 60 is based on the voltage |E s |sin(ωt) approaches |P load_ac |Adjust the power P by sin(2(ωt-135 degrees)) load pulsating electrical components.

[0133] In addition, similarly to control mode 6, the reverse flow operation is performed and the power P pcs The control mode 1 is negative (-) so long as the power P is adjusted so as to pulsate with a phase difference of 45 degrees with respect to the voltage of the single-phase AC power supply 100. load As in control mode 7, the reverse flow action and the power P pcs The positive (+) control mode 4 adjusts the power P by pulsating the voltage of the single-phase AC power supply 100 at a phase difference of 135 degrees. load And, obviously, the power P of the system grid-connected inverter 10 is pcs In the forward flow operation and the reverse flow operation, the phase is shifted by 90 degrees with respect to the voltage waveform of the single-phase AC power source 100 .

[0134] The power system 1 of Example 1, the power system 2 of the comparative example, and the power system 3 of Example 2 include solar panels 40 and batteries 50 as examples of DC power sources, but may also include either solar panels 40 or batteries 50. The power system 1 of Example 1, the power system 2 of the comparative example, and the power system 3 of Example 2 may also include other DC power sources. The power system 1 of Example 1, the power system 2 of the comparative example, and the power system 3 of Example 2 may each include two or more solar panels 40 and two or more DC / DC converters 41, or may each include two or more batteries 50 and two or more DC / DC converters 51.

[0135] The power system 1 of Example 1 and the power system 3 of Example 2 include an air conditioner 60 as an example of a DC load, i.e., an electrical device. The air conditioner 60 may be any device that includes a rotating electrical machine and adjusts the rotational speed or torque of the rotating electrical machine. In a rotating electrical machine that rotates via an inverter, the rotational speed is pulsated at a frequency of 2ω, twice that of the single-phase AC power supply 100, by a signal controlling the inverter. Similarly, in a rotating electrical machine that rotates via an inverter, the torque of the rotating machine is pulsated at a frequency of 2ω, twice that of the single-phase AC power supply 100, by a signal controlling the inverter. Even if the rotational speed or torque of the rotating electrical machine pulsates, the influence of the pulsation on the temperature of the space controlled by the air conditioner 60 including the rotating electrical machine is less likely to be noticeable.

[0136] The electrical equipment serving as a DC load may also be a heat pump device equipped with a heat pump circuit that circulates a heat medium. Examples of heat pump devices include air conditioners, hot water supply units, cooling units, and cooling devices that cool the air within a warehouse. Air conditioners may also be dedicated to cooling, dedicated to heating, or switchable between cooling and heating. Cooling devices cool the air within refrigerators, freezers, containers, and the like. Regarding the temperature controlled by the heat pump device, even if the power supplied from the power supply is pulsated at a frequency of 2ω, twice that of the single-phase AC power supply 100, the effects of the pulsation are unlikely to be significant.

[0137] The air conditioner 60 and the heat pump are shown as electrical devices serving as DC loads, but are not limited to the air conditioner 60 and the heat pump. Any electrical device may be used as long as the influence of the pulsation is not significant even if the consumed power is pulsated at a frequency 2ω that is twice that of the single-phase AC power supply 100. For example, thermal storage devices such as electric water heaters, blowers, and ventilation fans may also be used.

[0138] (Effects of the embodiment)

[0139] The power systems 1, 2, and 3 of the present embodiment include: a DC link unit 20; a grid-connected inverter 10 connected to the DC link unit 20 and configured to be connectable to a single-phase AC power source 100, and having a forward flow operation of converting AC power supplied from the single-phase AC power source 100 into DC power and supplying it to the DC link unit 20, and a reverse flow operation of converting DC power supplied from the DC link unit 20 into AC power and supplying it to the single-phase AC power source 100; one or more DC power sources, such as a solar panel 40 and a battery 50, connected to the DC link unit 20 and capable of supplying DC power to the DC link unit 20; The DC power supplied to the DC link unit 20 is supplied by a smoothing capacitor 30 connected to the DC link unit 20 to smooth the DC voltage of the DC link unit 20; and one or more electrical devices, such as air conditioners 60, 61 and a heat pump system, are connected to the DC link unit 20 and consume the DC power supplied from the DC link unit 20. The electrical devices have a pulsating power adjustment function that adjusts the pulsating power component of the DC power consumed by the electrical devices based on the operation of the grid-connected inverter 10 and the voltage phase of the single-phase AC power source 100. This pulsating power component is a frequency component that is an integer multiple of two or more of the power supply frequency of the single-phase AC power source within the DC power consumed by the electrical devices. This allows the pulsating power component to be adjusted based on the operation of the grid-connected inverter 10.

[0140] In power systems 1, 2, and 3 of the present embodiments, the grid-connected inverter 10 is configured to perform a parallel-off operation, in which neither AC power is converted to DC power nor DC power is converted to AC power. The pulsating power adjustment function of the electrical equipment adjusts the pulsating power component to near zero or does not adjust the pulsating power component during the parallel-off operation of the grid-connected inverter 10. This allows the pulsating power component to be adjusted according to the parallel-off operation of the grid-connected inverter 10.

[0141] In power systems 1, 2, and 3 of the present embodiments, the pulsating power adjustment function of the electrical equipment is adjusted to reduce the frequency component at twice the power supply frequency contained in the pulsating power component of the DC power supplied from the DC link unit 20 to the DC power supply or smoothing capacitor 30. This makes it possible to adjust the pulsating power component generated in single-phase AC.

[0142] In power systems 1, 2, and 3 of the present embodiments, the pulsating power adjustment function of the electrical equipment adjusts the amplitude of the frequency component at twice the power supply frequency included in the pulsating power component, as well as the phase difference between the voltage of single-phase AC power supply 100 and the frequency component at twice the power supply frequency included in the pulsating power component. This facilitates adjustment of the pulsating power component.

[0143] In power systems 1, 2, and 3 of the present embodiments, the pulsating power adjustment function of the electrical equipment has a first control mode. In this first control mode, when the grid-connected inverter 10 performs a reverse power operation in which the DC link unit 20 supplies the first DC power to the grid-connected inverter 10, the pulsating power component is adjusted so that the DC power consumed by the electrical equipment approaches the DC power obtained by subtracting the first DC power from the DC power supplied by the DC power source. This eliminates the need to suppress the output of the DC power source.

[0144] In power systems 1, 2, and 3 of the present embodiments, the pulsating power adjustment function of the electrical equipment includes a second control mode. In this second control mode, when the grid-connected inverter 10 performs a forward flow operation to supply the second DC power from the grid-connected inverter 10 to the DC link unit 20, the pulsating power component is adjusted so that the DC power consumed by the electrical equipment approaches the sum of the DC power supplied by the DC power source and the second DC power. This eliminates the need to suppress the output of the DC power source.

[0145] In the power systems 1, 2, and 3 of the present embodiments, the pulsating power adjustment function of the electrical equipment includes: a first control mode in which, when the DC power supplied from the DC link unit 20 to the grid-connected inverter 10 is a first DC power, the pulsating power component is adjusted so that the DC power consumed by the electrical equipment approaches the DC power obtained by subtracting the first DC power from the DC power supplied by the DC power source; a second control mode in which, when the DC power supplied from the grid-connected inverter 10 to the DC link unit 20 is a second DC power, the pulsating power component is adjusted so that the DC power consumed by the electrical equipment approaches the DC power obtained by subtracting the first DC power from the DC power supplied by the DC power source; and a third control mode in which the pulsating power component is adjusted so that the pulsating power component approaches zero, or is not adjusted. Thus, the pulsating power component can be adjusted according to the operation of the grid-connected inverter 10.

[0146] In power systems 1, 2, and 3 of the present embodiments, the grid-connected inverter 10 is configured to perform a parallel-off operation that does not convert AC power to DC power or vice versa. The pulsating power regulation function of the electrical equipment operates in the first control mode when the grid-connected inverter 10 is performing reverse power operation and the pulsating power component exceeds a predetermined threshold value. It operates in the third control mode when the grid-connected inverter 10 is performing reverse power operation and the pulsating power component is below the threshold value. It operates in the second control mode when the grid-connected inverter 10 is performing forward power operation and the pulsating power component exceeds the threshold value. It operates in the third control mode when the grid-connected inverter 10 is performing forward power operation and the pulsating power component is below the threshold value. It operates in the third control mode when the grid-connected inverter 10 is performing parallel-off operation. This reduces pulsation in the power consumed by the electrical equipment.

[0147] In power systems 1, 2, and 3 of the present embodiments, the grid-connected inverter 10 performs a parallel-off operation that does not convert AC power to DC power or vice versa. The pulsating power regulation function of the electrical equipment operates in the first control mode when the grid-connected inverter 10 operates in reverse flow mode, in the second control mode when the grid-connected inverter 10 operates in forward flow mode, and in the third control mode when the grid-connected inverter 10 operates in parallel-off mode. This reduces the capacitance of the smoothing capacitor 30.

[0148] In the power systems 1, 2, and 3 of the present embodiment, the electrical equipment includes a rotating electrical machine, and the pulsating power component is adjusted by adjusting the rotational speed or torque of the rotating electrical machine.

[0149] In the power systems 1, 2, and 3 of the present embodiment, the electrical equipment is a power system, and the power system is a heat pump system including a heat pump circuit. Therefore, the influence of power pulsation is not significant.

[0150] In the power systems 1, 2, and 3 of the present embodiment, the DC power source is a solar cell device, thereby facilitating connection to the power system.

[0151] In the power systems 1, 2, and 3 of the present embodiment, the DC power supply is a power storage device, thereby facilitating connection to the power system.

[0152] In this embodiment, electrical equipment, such as air conditioners 60 and 61 and heat pump equipment, consumes DC power supplied from the DC link unit 20. These electrical equipment include a pulsating power adjustment function that adjusts the pulsating power component based on the operation of the grid-connected inverter 10 and the voltage phase of the single-phase AC power source 100. The grid-connected inverter 10 is connected to the single-phase AC power source 100 and performs forward flow operation, converting the AC power supplied from the single-phase AC power source 100 into DC power and supplying it to the DC link unit 20, and reverse flow operation, converting the DC power supplied from the DC link unit 20 into AC power and supplying it to the single-phase AC power source 100. The pulsating power component is a frequency component of the DC power consumed by the electrical equipment that is an integer multiple of two or more of the power supply frequency of the single-phase AC power source 100. This makes it possible to adjust the pulsating power component based on the operation of the grid-connected inverter.

[0153] Although the embodiment has been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0154] Label Description

[0155] 1, 2, 3 Power systems; 10 System grid-connected inverter; 20 DC link unit; 30 Smoothing capacitor; 40 Solar panel; 41, 51 DC / DC converter; 50 Battery; 60, 61 Air conditioner; 100 Single-phase AC power supply.

Claims

1. A power system comprising: DC link department; a grid-connected inverter connected to the DC link unit and configured to be connectable to a single-phase AC power source, and having a forward flow operation for converting AC power supplied from the single-phase AC power source into DC power and supplying the power to the DC link unit, and a reverse flow operation for converting DC power supplied from the DC link unit into AC power and supplying the power to the single-phase AC power source; one or more DC power supplies connected to the DC link unit and configured to supply DC power to the DC link unit; a smoothing capacitor connected to the DC link portion to smooth a DC voltage of the DC link portion; and one or more electrical devices connected to the DC link unit and consuming DC power supplied from the DC link unit, In the power system, The electrical equipment has a pulsating power adjustment function for adjusting the pulsating power component according to the operation of the system grid-connected inverter and the voltage phase of the single-phase AC power supply. The pulsating power component is a frequency component in the DC power consumed by the electrical equipment that is an integer multiple of 2 or more of the power supply frequency of the single-phase AC power supply.

2. The power system according to claim 1, wherein: The grid-connected inverter has a disconnecting operation that does not convert AC power into DC power or convert DC power into AC power. The pulsating power adjustment function of the electrical device adjusts the pulsating power component so as to approach zero, or does not adjust the pulsating power component, when the grid-connected inverter performs a parallel-off operation.

3. The power system according to claim 1 or 2, wherein: The pulsating power adjustment function of the electrical device adjusts the pulsating power component in the DC power supplied from the DC link unit to the DC power supply or the smoothing capacitor so as to reduce a frequency component twice the power supply frequency included in the pulsating power component.

4. The power system according to claim 1 or 2, wherein: The pulsating power adjustment function of the electrical device adjusts the amplitude of the frequency component of twice the power supply frequency contained in the pulsating power component and the phase difference between the voltage of the single-phase AC power supply and the frequency component of twice the power supply frequency contained in the pulsating power component.

5. The power system according to claim 1 or 2, wherein: The pulsating power adjustment function of the electrical device has a first control mode. In this first control mode, when the system grid-connected inverter performs a reverse flow operation of supplying first DC power from the DC link unit to the system grid-connected inverter, the pulsating power component is adjusted in such a manner that the DC power consumed by the electrical device approaches the DC power obtained by subtracting the first DC power from the DC power supplied by the DC power supply.

6. The power system according to claim 1 or 2, wherein: The pulsating power adjustment function of the electrical device has a second control mode. In this second control mode, when the system grid-connected inverter performs a forward flow operation of supplying the second DC power from the system grid-connected inverter to the DC link unit, the pulsating power component is adjusted in such a manner that the DC power consumed by the electrical device approaches the DC power that is the sum of the DC power supplied by the DC power supply and the second DC power.

7. The power system according to claim 1, wherein: The pulsating power adjustment function of the electrical device includes: a first control mode for adjusting the pulsating power component so that the DC power consumed by the electrical device approaches a DC power obtained by subtracting the first DC power from the DC power supplied by the DC power supply when the DC power supplied from the DC link unit to the grid-connected inverter is a first DC power; a second control mode for adjusting the pulsating power component so that the DC power consumed by the electrical device approaches the sum of the DC power supplied by the DC power source and the second DC power when the DC power supplied from the grid-connected inverter to the DC link unit is set to a second DC power; as well as In the third control mode, the pulsating power component is adjusted so as to approach zero, or the pulsating power component is not adjusted.

8. The power system according to claim 7, wherein: The grid-connected inverter has a disconnecting operation that does not convert AC power into DC power or convert DC power into AC power. Regarding the pulsating power adjustment function of the electrical equipment, When the grid-connected inverter performs reverse power operation and the pulsating power component exceeds a predetermined threshold value, the first control mode is used; and when the grid-connected inverter performs reverse power operation and the pulsating power component is below the threshold value, the third control mode is used. When the grid-connected inverter performs a forward flow operation and the pulsating power component exceeds the threshold value, the second control mode is used; when the grid-connected inverter performs a forward flow operation and the pulsating power component is below the threshold value, the third control mode is used. When the grid-connected inverter performs a parallel-off operation, it functions in the third control mode.

9. The power system according to claim 7, wherein: The grid-connected inverter has a disconnecting operation that does not convert AC power into DC power or convert DC power into AC power. Regarding the pulsating power adjustment function of the electrical equipment, When the grid-connected inverter of the system performs reverse power flow operation, the system functions in the first control mode. When the grid-connected inverter of the system performs a down-flow operation, the second control mode functions. The third control mode is used when the grid-connected inverter performs a parallel-off operation.

10. The power system according to claim 1 or 2, wherein: The electric device includes a rotating electric machine, and the pulsating power component is adjusted by adjusting the rotational speed or torque of the rotating electric machine.

11. The power system according to claim 1 or 2, wherein: The electrical device is a heat pump device including a heat pump circuit.

12. The power system according to claim 1 or 2, wherein: The DC power source is a solar cell device.

13. The power system according to claim 1 or 2, wherein: The DC power supply is a power storage device.

14. An electric device that consumes DC power supplied from a DC link unit, wherein: The electrical equipment has a pulsating power adjustment function for adjusting a pulsating power component according to the operation of a system grid-connected inverter and the voltage phase of a single-phase AC power supply. The system grid-connected inverter is connected to the single-phase AC power supply and has a forward flow operation for converting the AC power supplied from the single-phase AC power supply into DC power and supplying the resultant to the DC link unit, and a reverse flow operation for converting the DC power supplied from the DC link unit into AC power and supplying the resultant to the single-phase AC power supply. The pulsating power component is a frequency component of the DC power consumed by the electrical equipment that is an integer multiple of 2 or more of the power supply frequency of the single-phase AC power supply.

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