Control device, power conditioner, heat pump system, and power pulsation adjustment system

Abstract

When a grid-connected inverter connected to a DC link unit and linked to a three-phase grid power supply outputs three-phase unbalanced power, power pulsation occurring in the DC link unit is compensated for by equipment provided in the DC link unit. [Solution] The control device controls one or more devices that transmit first DC power to a DC link unit or receive first DC power from the DC link unit, the first DC power including a first power pulsation which is an AC component, the DC link unit is connected to the DC link unit and is configured to be able to transmit and receive second DC power between a grid-connected inverter connected to a three-phase grid power source, the control device includes a pulsation detection unit that detects second power pulsation which is an AC component included in the second DC power, and adjusts the first power pulsation in accordance with the second power pulsation detected by the pulsation detection unit.

Description

[Technical Field]

[0001] The present disclosure relates to a control device, a power conditioner, a heat pump system, and a power pulsation regulating system. [Background technology]

[0002] For example, Non-Patent Document 1 discloses a self-commutated static var compensator (self-commutated SVC) as a device that compensates for three-phase imbalance and voltage fluctuations in a three-phase AC line. The self-commutated SVC is configured with a voltage-source inverter, and three phases are configured using three single-phase inverter circuits. It also describes that each of the three phases of the self-commutated SVC is connected to a respective phase of the three-phase AC line to compensate for three-phase imbalance and voltage fluctuations. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Masatoshi Takeda, Noboru Murakami, Akihiro Iizuka, Yoshifumi Mochinaga, "Development of a Three-Phase Unbalanced Voltage Fluctuation Compensator Using a Self-Commutated Static Reactive Power Compensator," T. IEE Japan, Vol. 116-D, No.8, 1996, pp. 826-834 Summary of the Invention [Problem to be solved by the invention]

[0004] When a single-phase load is connected to a three-phase AC line, a three-phase imbalance occurs. In conventional technology, a compensation circuit is installed in the three-phase AC line to compensate for the three-phase imbalance. Alternatively, a grid-connected inverter connected to the three-phase AC line can output three-phase unbalanced power to compensate for the three-phase imbalance caused by the single-phase load. In this case, power pulsation occurs in the DC link connected to the grid-connected inverter, so a technology to reduce the power pulsation is required.

[0005] The present disclosure aims to compensate for power pulsation that occurs in a DC link unit by a device provided in the DC link unit when a grid-connected inverter that is connected to a DC link unit and connected to a three-phase grid power supply outputs three-phase unbalanced power. [Means for solving the problem]

[0006] A control device according to a first aspect is a control device that controls one or more devices that transmit first DC power to a DC link unit or receive the first DC power from the DC link unit, wherein the first DC power includes a first power ripple that is an AC component, the DC link unit is connected to the DC link unit and is configured to transmit and receive second DC power to and from a grid-connected inverter that is connected to a three-phase grid power source, the control device includes a ripple detection unit that detects second power ripple that is an AC component included in the second DC power, and adjusts the first power ripple in accordance with the second power ripple detected by the ripple detection unit, thereby compensating for power ripple occurring in the DC link unit. A control device according to a second aspect is the control device according to the first aspect, wherein the DC link unit is configured to transmit and receive third DC power to and from a capacitor connected to the DC link unit, and the control device adjusts the first power pulsation so as to reduce third power pulsation, which is an AC component included in the third DC power, thereby reducing the power pulsation absorbed by the capacitor. A control device according to a third aspect is the control device according to the first or second aspect, and adjusts the amplitude difference and phase difference between the second power pulsation and the first power pulsation, thereby compensating for power pulsation occurring in a DC link unit. A control device according to a fourth aspect is the control device according to any one of the first to third aspects, wherein the first power pulsation is adjusted to approach the second power pulsation, thereby compensating for power pulsation occurring in a DC link unit. A control device according to a fifth aspect is the control device according to any one of the first to fourth aspects, wherein the device is a compensation circuit connected to a power source and converts power from the power source into the first DC power, thereby enabling the device transmitting the first DC power to compensate for power pulsation occurring in the DC link unit. A control device according to a sixth aspect is the control device according to any one of the first to fourth aspects, wherein the device is an electric device that receives the first DC power. This makes it possible to compensate for power pulsation occurring in a DC link unit without providing any special device. A seventh aspect of the present invention relates to the control device of any one of the first to sixth aspects, wherein the pulsation detector acquires information correlated with the second power pulsation from the grid-connected inverter, thereby making it possible to compensate for power pulsation occurring in the DC link in accordance with the operation of the grid-connected inverter. A control device according to an eighth aspect is the control device according to any one of the first to sixth aspects, wherein the pulsation detector includes a DC power measuring unit that measures the second DC power, thereby making it possible to compensate for power pulsation occurring in the DC link unit in accordance with the second power pulsation detected by the pulsation detector. A control device according to a ninth aspect is the control device according to any one of the first to eighth aspects, wherein the second power pulsation pulsates at a frequency twice the power supply frequency of the system power supply, thereby making it possible to compensate for the power pulsation contained in the system power supply. A control device according to a tenth aspect is the control device according to any one of the first to eighth aspects, wherein the second power pulsation pulsates at a frequency that is an integer multiple of twice the power supply frequency of the system power supply, or a frequency that is an integer fraction of twice the power supply frequency of the system power supply. This makes it possible to compensate for harmonic components contained in the system power supply or power pulsation due to equipment using frequency division control. A control device according to an eleventh aspect is the control device according to the sixth aspect, wherein the electric device includes a rotating electric machine. This makes it possible to compensate for power pulsation occurring in the DC link without impairing the function of the electric device. A control device according to a twelfth aspect is the control device according to the eleventh aspect, wherein the control device adjusts the first power pulsation by adjusting the rotation speed or torque of the rotating electric machine, thereby making it possible to compensate for the power pulsation occurring in the DC link without impairing the function of the electric device. A power conditioner according to a thirteenth aspect includes the control device according to any one of the first to twelfth aspects, one or more devices controlled by the control device, a DC link unit to which the devices are connected, and a grid-connected inverter configured to be connectable to a three-phase power grid and connected to the DC link unit, thereby extending the life of the power conditioner. A heat pump system according to a fourteenth aspect is the power conditioner according to the thirteenth aspect, further comprising a refrigeration device as the equipment. A pulsating power regulation system according to a fifteenth aspect includes the control device according to any one of the first to twelfth aspects, and one or more devices controlled by the control device. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a power system including a control device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram illustrating a conventional technique. [Figure 3] 10A and 10B are diagrams illustrating a method for adjusting power pulsation in the present embodiment. [Figure 4] FIG. 2 is a diagram defining the amplitude −ΔP and phase α of the power pulsation. [Figure 5] FIG. 1 is a diagram illustrating control pattern 1. [Figure 6] FIG. 10 is a diagram illustrating control pattern 2. [Figure 7] FIG. 10 is a diagram illustrating control pattern 3. [Figure 8] FIG. 10 is a diagram illustrating control pattern 4. [Figure 9] FIG. 10 is a diagram illustrating a control pattern 5. [Figure 10] FIG. 10 is a diagram illustrating a control pattern 6. [Figure 11] FIG. 10 is a diagram illustrating a control pattern 7. [Figure 12] 10 is an example of an output waveform of a single-phase frequency division control thyristor. [Figure 13] FIG. 2 is a diagram showing an example of a detailed circuit diagram of the present embodiment. [Figure 14] 10A and 10B are diagrams illustrating other examples of compensation circuits, where (a) is an example of a step-down active buffer circuit, and (b) is an example of a series voltage injector. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing an example of a power system including a control device according to the present embodiment. The power system 1 includes a grid-connected inverter 10, a DC link unit 20, a capacitor 30, a solar panel 40, a DC / DC converter 41, a compensation circuit 42, an air conditioner 50, a single-phase load 60, and a control device 70. The power system 1 is connected to a three-phase power supply system 100. The three-phase power supply system 100 is, for example, 200 V, 50 Hz. In the diagram, the grid-connected inverter 10 is referred to as a grid-connected INV, and the DC / DC converter 41 is referred to as a DC / DC. In the diagram, the right side of the grid-connected inverter 10 may be referred to as an AC line, and the left side of the grid-connected inverter 10 may be referred to as a DC line.

[0009] The grid-connected inverter 10 has two input / output units through which power is input and output. One of the input / output units of the grid-connected inverter 10 is configured to be connectable to a three-phase grid power supply 100. The other input / output unit of the grid-connected inverter 10 is connected to a DC link unit 20. The capacitor 30 is connected to the DC link unit 20. The solar panel 40 is connected to the DC link unit 20 via a DC / DC converter 41 and a compensation circuit 42. In the example shown in FIG. 1 , the compensation circuit 42 is connected to the DC / DC converter 41, but this is not limiting. The compensation circuit 42 may be integrated with the DC / DC converter 41. The air conditioner 50 is connected to the DC link unit 20. The solar panel 40, the DC / DC converter 41, the compensation circuit 42, and the air conditioner 50 are examples of one or more devices that transmit first DC power to the DC link unit 20 or receive first DC power from the DC link unit 20. A single-phase load 60 is connected to a three-phase AC line between the grid-connected inverter 10 and a three-phase grid power supply 100 .

[0010] The grid-connected inverter 10 performs forward flow operation, reverse flow operation, and parallel-off operation. In forward flow operation, AC power is converted into DC power and supplied from the three-phase grid power supply 100 side to the DC link unit 20 side. In reverse flow operation, DC power is converted into three-phase AC power and supplied from the DC link unit 20 side to the three-phase grid power supply 100 side. The grid-connected inverter 10 is an inverter that can supply power in both directions. In reverse flow operation and forward flow operation, the AC line side and the DC line side operate in parallel via the grid-connected inverter 10. In parallel-off operation, neither the reverse flow operation that converts DC power to AC power nor the forward flow operation that converts AC power to DC power is performed. In parallel-off operation, the AC line side and the DC line side operate separately. The grid-connected inverter 10 interconnects an AC power system (here, a three-phase power supply system) and a DC power system.

[0011] The DC link unit 20 is capable of transmitting and receiving DC power to and from the grid-connected inverter 10. One of the two current paths is positive (+) and the other is negative (-), which are DC current paths. The capacitor 30 is connected between the two current paths of the DC link unit 20 and adjusts pulsation occurring in the DC power. The capacitor 30 is, for example, a ceramic capacitor, a film capacitor, or an electrolytic capacitor.

[0012] The solar panel 40 converts light energy into electrical energy through the photovoltaic effect. The DC / DC converter 41 is provided between the solar panel 40 and the DC link unit 20 , and converts the DC voltage output by the solar panel 40 into a DC voltage for the DC link unit 20 . The compensation circuit 42 compensates for power pulsation occurring in the DC link section 20 .

[0013] DC / DC converter 41 may be configured to have a function of performing power conversion in only one direction, converting DC power input from the primary side into predetermined DC power and outputting it to the secondary side. Alternatively, the DC / DC converter may be configured to perform power conversion in both directions, having a function of converting DC power input from the secondary side into predetermined DC power and outputting it to the primary side, in addition to the function of converting DC power input from the primary side into predetermined DC power and outputting it to the secondary side.

[0014] The circuit configuration of the DC / DC converter 41 is selected from among a step-down circuit, a step-up circuit, and a step-up / step-down circuit depending on the voltage value of the power supply or DC line to be connected. DC / DC converter 41 is an example of a converter. However, the converter is not limited to a DC / DC converter, and may be an AC / DC converter that is connected to an AC power source and converts AC voltage into DC voltage.

[0015] The air conditioner 50 consumes DC power supplied from the DC link unit 20. The air conditioner 50 includes a rotating electric machine and compensates for power pulsation generated in the DC link unit 20 by adjusting the rotation speed or torque of the rotating electric machine. A refrigeration device or a ventilation device may be used instead of the air conditioner 50. The refrigeration device may be, for example, an air conditioner, a water heater, a chiller unit, or a cooling device that cools the air inside a storage unit. The air conditioner may be a dedicated cooling device, a dedicated heating device, or an air conditioner that switches between cooling and heating. The cooling device cools the air inside a refrigerator, a freezer, a container, etc. The single-phase load 60 is an electrical appliance such as a lamp or heater that operates on an AC power source. The control device 70 controls the compensation circuit 42 and the air conditioner 50 to compensate for power pulsation occurring in the DC link unit 20. In the example shown in FIG. 1, the control device 70 is independent, but it may also be integrated with the compensation circuit 42 or the air conditioner 50. The control device 70, the DC / DC converter 41, the compensation circuit 42 and the air conditioner 50 constitute a power pulsation adjustment system.

[0016] The grid-connected inverter 10, the DC link unit 20, the capacitor 30, the control device 70, and the DC / DC converter 41 can be regarded as part of a power conditioner. Furthermore, when a refrigeration unit is connected as an electrical device to the DC link unit 20 in the power conditioner, the power conditioner can be regarded as a heat pump system.

[0017] 1 defines the names of the power and the direction in which the power is supplied to each device and the grid-connected inverter 10. In FIG. 1, the direction in which the power is supplied is indicated by an arrow. The power supplied by the solar panel 40 is converted to power P PV Power P PV The direction in which the current is supplied from the solar panel 40 to the DC link unit 20 is positive (+). The power supplied from the DC link unit 20 to the air conditioner 50 is P load Power P loadThe direction in which the power is supplied from the DC link unit 20 side to the air conditioner 50 side is positive (+). PV and power P load is an example of the first DC power. The power transmitted and received between the DC link unit 20 and the grid-connected inverter 10 is P DC Power P DC The direction in which the power is supplied from the DC link unit 20 to the grid-connected inverter 10 is defined as positive (+). DC is an example of the second DC power. The grid-connected inverter 10 outputs three-phase power, u-phase, v-phase, and w-phase. u , v-phase power is P v , w-phase power is P w Power P u , P v and P w The direction in which the current is supplied from the grid-connected inverter 10 side to the three-phase grid power supply 100 side is positive (+).

[0018] 2 is a diagram illustrating the prior art. A grid-connected inverter 10 connected to a three-phase grid power supply 100 outputs three-phase balanced power to a three-phase AC line. If there is a difference in the power consumed by each single-phase load 60 connected to the three-phase AC line, three-phase unbalanced power occurs between the single-phase load 60 and the three-phase grid power supply 100. Since it is not possible to supply power to the three-phase grid power supply 100 in a state of three-phase unbalanced power, a compensation circuit is connected to compensate the three-phase unbalanced power to three-phase balanced power, and then power is supplied to the three-phase grid power supply 100. In this case, the grid-connected inverter 10 outputs three-phase balanced power, so no power pulsation occurs in the DC link unit 20.

[0019] FIG. 3 is a diagram illustrating a method for adjusting power pulsation in this embodiment. The grid-connected inverter 10 outputs three-phase unbalanced power to a three-phase AC line. When the grid-connected inverter 10 outputs three-phase unbalanced power corresponding to the power consumed by each single-phase load 60, the power between the single-phase load 60 and the three-phase grid power supply 100 becomes three-phase balanced, and power can be supplied directly to the three-phase grid power supply 100. In this case, the grid-connected inverter 10 outputs three-phase unbalanced power, causing power pulsation in the DC link unit 20. Power pulsation in the DC link unit 20 may shorten the life of the devices and capacitor 30 connected to the DC link unit, so it is necessary to adjust the power pulsation. In this embodiment, the power pulsation is adjusted by pulsating the power of the DC link unit 20 so as to cancel out the power pulsation generated in the DC link unit 20.

[0020] Next, a method for adjusting the power pulsation occurring in the DC link unit 20 will be described. It is assumed that the grid-connected inverter 10 outputs three-phase unbalanced power autonomously or as a result. The power P of each phase of the grid-connected inverter 10 that outputs three-phase unbalanced power is u , P v and P w are defined by equations (1), (2), and (3), respectively. The u-phase power P u is expressed by equation (1). The amplitude is 2P, which is the smallest of the three phases. θ is the phase of the AC power. The power of the v phase, P v is expressed by equation (2). The amplitude is 2P α The w-phase power P w is expressed by equation (3). The amplitude is 2P β and the phase is shifted by 4 / 3π (240°). The actual respective power can be calculated from the single-phase load 60 connected between the grid-connected inverter 10 and the three-phase grid power supply 100 .

[0021]

number

[0022] The total power output by the grid-connected inverter 10 is expressed by equation (4). Fig. 4 is a diagram defining the amplitude -ΔP and phase α of the power pulsation. As shown in Fig. 4, the amount by which the power of the v-phase and w-phase is greater than the power of the u-phase, i.e., -P α cos(2θ-4 / 3π) and -P β cos(2θ-2 / 3π) is generated as a vector. If the amplitude of the component obtained by combining these two vectors is -ΔP and the phase is α, then equation (4) can be rewritten as equation (5). In equation (5), {-ΔPcos(2θ-α)} is the power ripple.

[0023]

number

[0024] The power expressed by the formula (5) is the power P DC Therefore, the power P DC is expressed by equation (6). That is, due to the three-phase unbalanced power output from the grid-connected inverter 10, power pulsation, which is an AC component and is expressed as {-ΔPcos(2θ-α)}, occurs in the DC link unit 20. The power pulsation occurring in the DC link unit 20 is an example of a second power pulsation.

[0025]

number

[0026] The power pulsation occurring in the DC link unit 20 is compensated for by controlling the power of the devices connected to the DC link unit 20. Specifically, a power pulsation that is 180° out of phase with the power pulsation occurring in the DC link unit 20 is generated to cancel out the power pulsation occurring in the DC link unit 20. There are two possible methods for canceling out the power pulsation: a method of compensation using the compensation circuit 42, and a method of absorption by the load of the air conditioner 50.

[0027] When compensation is performed by the compensation circuit 42, the power P PV is controlled as shown in equation (7). PV_dc is the DC power generated by the solar panel 40, and is the normal component. To this normal component, an AC component whose amplitude information and phase information are matched with the power ripple expressed by equation (6) is added. P PV_ac is the amplitude of the AC component, and (2θ-α) is the phase of the AC component. P PV_ac cos(2θ-α) is an example of the first power pulsation. This adjusts the amplitude difference and phase difference between the second power pulsation and the first power pulsation. DC power P pv_dc is determined by MPPT (Maximum Power Point Control).

[0028] When compensating for power pulsation due to the load of the air conditioner 50, the power P supplied from the DC link unit 20 to the air conditioner 50 is load is controlled as shown in equation (8). load It can also be said that P is the power consumed by the air conditioner 50. load_dc is the DC power consumed by the air conditioner 50, and is the normal component. To this normal component, an AC component whose amplitude information and phase information match the power pulsation expressed by equation (6) is added. P load_ac is the amplitude of the AC component, and (2θ-α) is the phase of the AC component. P load_ac cos(2θ-α) is another example of the first power pulsation. This adjusts the amplitude and phase difference between the second power pulsation and the first power pulsation. P load_dc is determined by the required air conditioning capacity. The time constant of the heat load handled by the air conditioner 50 is large compared to the time constant of the power pulsation of the DC link unit 20. Therefore, the power P consumed by the air conditioner 50 load Pulsating the air conditioner 50 does not impair the function of the air conditioner 50.

[0029]

number

[0030] The cases where the power pulsation occurring in the DC link unit 20 is compensated for only by the compensation circuit 42 and only by the air conditioner 50 have been described. In addition, there is also a case where the power pulsation occurring in the DC link unit 20 is compensated for using both the compensation circuit 42 and the air conditioner 50. In this case, the power P output by the compensation circuit 42 is adjusted so as to achieve the energy balance expressed by equation (9). PV and the power P consumed by the air conditioner 50 load In equation (9), the power P load The reason why there is a minus (-) sign in front of the power P load This is because the direction of the current supplied from the DC link unit 20 side to the air conditioner 50 side is defined as positive (+).

[0031] When the power pulsation occurring in the DC link unit 20 is compensated for only by the compensation circuit 42, the amplitude of the AC component has the relationship expressed by equation (10) due to the energy balance. When the power pulsation occurring in the DC link unit 20 is compensated for only by the air conditioner 50, the amplitude of the AC component has the relationship expressed by equation (11). When the power pulsation occurring in the DC link unit 20 is compensated for by both the compensation circuit 42 and the air conditioner 50, the amplitude of the AC component has the relationship expressed by equation (12). In this way, the amplitude P of the power pulsation occurring in the compensation circuit 42 PV_ac and the amplitude P of the power pulsation consumed by the air conditioner 50 load_ac The power pulsation occurring in the DC link unit 20 is cancelled by adjusting the sum of the above to the amplitude −ΔP of the power pulsation occurring in the DC link unit 20.

[0032]

number

[0033] DC power is transmitted and received between the DC link unit 20 and the capacitor 30. The capacitor 30 absorbs power pulsation, which is an AC component included in the DC power. When the power pulsation generated in the DC link unit 20 is large, the required capacity of the capacitor 30 increases. In this embodiment, the power pulsation included in the DC power transmitted and received between the DC link unit 20 and the capacitor 30 is compensated for by the compensation circuit 42 and the air conditioner 50. The DC power transmitted and received between the DC link unit 20 and the capacitor 30 is an example of third DC power. The power pulsation included in the DC power transmitted and received between the DC link unit 20 and the capacitor 30 is also an example of third power pulsation. In other words, the control device 70 adjusts the first power pulsation so as to reduce the third power pulsation, which is an AC component included in the third DC power. More specifically, the control device 70 adjusts the first power pulsation so as to reduce the third power pulsation, which is an AC component included in the third DC power and pulsates at the same frequency as the second power pulsation, thereby reducing the power pulsation absorbed by the capacitor 30, allowing the capacitance of the capacitor 30 to be reduced.

[0034] Example 1 In the first embodiment, the power pulsation occurring in the DC link unit 20 is compensated for based on information on the power output by the grid-connected inverter 10. FIG. 5 is a diagram illustrating a control pattern 1. The grid-connected inverter 10 compensates for the power pulsation occurring in the DC link unit 20 based on information on the power output by the grid-connected inverter 10. u , P v and P w The control device 70 calculates the power pulsation occurring in the DC link unit 20 based on the information received from the grid-connected inverter 10. The output power P u , P v and P wThe information relating to the second power pulsation can be said to be information correlated with the power pulsation occurring in the DC link unit 20. The control device 70 has a function as a pulsation detection unit. In other words, the pulsation detection unit obtains information correlated with the second power pulsation from the grid-connected inverter 10.

[0035] In control pattern 1, the control device 70 issues amplitude and phase commands, P load_ac * and α * The air conditioner 50 transmits the power pulsation P load_ac cos(2θ-α) is the DC power P load_dc This compensates for the power pulsation occurring in the DC link unit 20.

[0036] 6 is a diagram illustrating control pattern 2. In control pattern 1, the control device 70 transmits commands related to amplitude and phase to the air conditioner 50. In contrast, in control pattern 2, the control device 70 transmits commands related to amplitude and phase, P PV_ac * and α * The compensation circuit 42 transmits the power pulsation P PV_ac cos(2θ-α) is the DC power P generated by the solar panel 40 PV_dc In this way, the power pulsation occurring in the DC link unit 20 is compensated for.

[0037] 7 is a diagram illustrating control pattern 3. In control pattern 3, the control device 70 transmits commands related to amplitude and phase to both the air conditioner 50 and the compensation circuit 42 based on the calculation results of the power pulsation. At this time, the control device 70 calculates the amplitude P load_ac and the amplitude P of the power pulsation generated by the compensation circuit 42 PV_ac A command is sent to the air conditioner 50 and the compensation circuit 42 so that the equation (12) is satisfied. In this way, the power pulsation occurring in the DC link unit 20 is compensated for.

[0038] Example 2 In the first embodiment, the power pulsation occurring in the DC link unit 20 is compensated for based on information about the power output by the grid-connected inverter 10. In contrast, in the second embodiment, the power pulsation occurring in the DC link unit 20 is directly detected and compensated for. FIG. 8 is a diagram illustrating control pattern 4. The power system 2 includes a detection unit 80. The detection unit 80 is an example of a DC power measurement unit. Since the other configurations are the same as those of the power system 1 shown in FIG. 5, the same reference numerals are used and descriptions thereof will be omitted.

[0039] The detection unit 80 detects the power P transmitted and received between the DC link unit 20 and the grid-connected inverter 10. DC The detection unit 80 may be, for example, a fluxgate current sensor. The control device 70 measures the power P DC The information relating to the power pulsation is subjected to a Fourier transform to identify information relating to the amplitude and phase of the power pulsation. Since the frequency of the power pulsation is mainly twice the power supply frequency of the grid power supply, the Fourier transform is performed focusing on this frequency. The grid power supply also contains pulsation of harmonic components that are an integer multiple of twice the power supply frequency. In the control device 70 of the second embodiment, by changing the frequency to be focused on when performing the Fourier transform, it is possible to compensate for power pulsation of a frequency that is an integer multiple of twice the power supply frequency.

[0040] In control pattern 4, the control device 70 issues amplitude and phase commands to the air conditioner 50 based on information about the amplitude and phase of the power pulsation obtained by Fourier transform. load_ac * and α * The air conditioner 50 transmits the power pulsation P load_ac cos(2θ-α) is the DC power P load_dc This compensates for the power pulsation occurring in the DC link unit 20.

[0041] 9 is a diagram illustrating control pattern 5. In control pattern 5, the control device 70 issues commands related to amplitude and phase to the compensation circuit 42, P PV_ac * and α* The compensation circuit 42 transmits the power pulsation P PV_ac cos(2θ-α) is the DC power P generated by the solar panel 40 PV_dc In this way, the power pulsation occurring in the DC link unit 20 is compensated for.

[0042] 10 is a diagram illustrating control pattern 6. In control pattern 6, the control device 70 transmits commands related to the amplitude and phase to both the air conditioner 50 and the compensation circuit 42 based on information related to the amplitude and phase of the power pulsation obtained by Fourier transform. At this time, the control device 70 transmits commands related to the amplitude P load_ac and the amplitude P of the power pulsation generated by the compensation circuit 42 PV_ac A command is sent to the air conditioner 50 and the compensation circuit 42 so that the equation (12) is satisfied. In this way, the power pulsation occurring in the DC link unit 20 is compensated for.

[0043] (Modification of Example 2) When a device using frequency division control is used as a single-phase load 60 connected to a three-phase AC line, power pulsation at a frequency other than twice the power supply frequency occurs in the DC link unit 20. Fig. 11 is a diagram explaining control pattern 7. In the power system 3, one of the single-phase loads 60 is a single-phase load 61 using frequency division control.

[0044] The frequency division control method controls the ratio of current-carrying times within a fixed period of time. Figure 12 shows an example of the output waveform of a single-phase frequency division control thyristor. In this example, when the output is 75%, current flows for three AC power cycles, and there is no current flow for one cycle. When the output is 50%, current flows and no current flows alternately for each cycle. When the output is 25%, current flows for one AC power cycle, and there is no current flow for three cycles. When the output is 75% and 25%, power fluctuations occur with a period four times that of the AC power. When the output is 50%, power fluctuations occur with a period twice that of the AC power. In other words, when the output is 75% and 25%, power fluctuations occur at 1 / 4 the power supply frequency, and when the output is 50%, power fluctuations occur at 1 / 2 the power supply frequency. In such a case, power pulsation occurs in the DC link unit 20 at a frequency that is half or a quarter of the power supply frequency.

[0045] In the control pattern 7, similarly to the control pattern 4, the detection unit 80 detects the power P DC The control device 70 measures the power P DC The information about is Fourier transformed to identify information about the amplitude and phase of the power ripple.

[0046] The control device 70 issues a command regarding the amplitude and phase to the air conditioner 50 based on the information regarding the amplitude and phase of the power pulsation obtained by the Fourier transform. load_ac * and α * The air conditioner 50 transmits the power pulsation P load_ac cos(2θ-α) is the DC power P load_dc This compensates for power pulsation that occurs in the DC link unit 20 and pulsates at a frequency that is an integer fraction of the power supply frequency of the system power supply. Although the method of compensating for power pulsation by the air conditioner 50 has been described above, the present invention is not limited to this. The power pulsation may be compensated for by the compensation circuit 42, or may be compensated for by both the air conditioner 50 and the compensation circuit 42.

[0047] Fig. 13 is a diagram showing an example of a detailed circuit diagram of this embodiment. The circuit diagram of Fig. 13 includes a grid-connected inverter 10, a grid-connected inverter control board 11, a DC link unit 20, a capacitor 30, a solar panel 40, a DC / DC converter 41, a compensation circuit 42, an air conditioner 50, a pulsation compensation control board 71, a detection unit 80, and a detection circuit 81. In the figure, the grid-connected inverter control board 11 is referred to as a grid-connected INV control board.

[0048] The grid-connected inverter 10 may be, for example, one that uses an IGBT (insulated gate bipolar transistor) as a switching element. The grid-connected inverter control board 11 transmits a control signal to the grid-connected inverter 10 to control the three-phase power output by the grid-connected inverter 10. The control signal is, for example, a gate signal that controls the IGBT. The grid-connected inverter control board 11 also transmits information about the output power of the grid-connected inverter 10 to the pulsation compensation control board 71. The grid-connected inverter control board 11 is configured by, for example, a CPU, RAM, ROM, etc. The detector 80 measures the DC power of the DC link unit 20. The detector circuit 81 amplifies a signal relating to the DC power measured by the detector 80 and transmits it to the ripple compensation control board 71.

[0049] The compensation circuit 42 generates power pulsation in the DC link unit 20. An example of the compensation circuit 42 is a boost active buffer circuit. The boost active buffer circuit is composed of a boost chopper and a buffer capacitor. For example, a MOSFET, a HEMT, a bipolar transistor, an IGBT, or the like is used as a switching element for the boost chopper.

[0050] The pulsation compensation control board 71 is an example of the control device 70. The pulsation compensation control board 71 is configured with, for example, a CPU, RAM, ROM, etc. The pulsation compensation control board 71 calculates the power pulsation occurring in the DC link unit 20 based on information related to the output power of the grid-connected inverter 10 received from the grid-connected inverter control board 11. The pulsation compensation control board 71 transmits control signals as commands to the compensation circuit 42 and the air conditioner 50 based on the calculated power pulsation. The control signal transmitted to the compensation circuit 42 is, for example, a gate signal that controls a MOSFET. The control signal transmitted to the air conditioner 50 is, for example, a torque command.

[0051] The pulsation compensation control board 71 performs a Fourier transform on the signal related to the DC power received from the detection circuit 81, and identifies information related to the amplitude and phase of the power pulsation occurring in the DC link unit 20. Based on the identified information related to the amplitude and phase of the power pulsation, the pulsation compensation control board 71 transmits control signals as commands to the compensation circuit 42 and the air conditioner 50.

[0052] In the circuit diagram shown in FIG. 13, the compensation circuit 42 is a boost active buffer circuit. However, the compensation circuit 42 is not limited to this. FIG. 14 shows another example of the compensation circuit 42. The compensation circuit 42 shown in FIG. 14(a) is a buck active buffer circuit. A buck active buffer circuit is composed of a buck chopper and a buffer capacitor. A MOSFET, for example, is used as the switching element of the buck chopper. The compensation circuit 42 shown in FIG. 14(b) is a series voltage injector (SVI). The series voltage injector is composed of an H-bridge circuit with an LC output filter and a flying buffer capacitor. A MOSFET, for example, is used as the switching element of the H-bridge circuit. Although three types of compensation circuits 42 have been exemplified, namely, a step-up active buffer circuit, a step-down active buffer circuit, and a series voltage injector, the compensation circuit 42 is not limited to these and may be a compensation circuit other than these three types.

[0053] (Effects of the embodiment) The control device 70 of this embodiment controls one or more devices, such as a compensation circuit 42 and an air conditioner 50, that transmit or receive first DC power to or from the DC link unit 20. The first DC power includes a first power pulsation that is an AC component. The DC link unit 20 is connected to the DC link unit 20 and is configured to transmit or receive second DC power to or from a grid-connected inverter 10 that is connected to a three-phase grid power source 100. The control device 70 includes a pulsation detection unit, such as a pulsation compensation control board 71, a detection unit 80, and a detection circuit 81, that detects second power pulsation that is an AC component included in the second DC power. The control device 70 adjusts the first power pulsation in accordance with the second power pulsation detected by the pulsation detection unit. This allows the power pulsation generated in the DC link unit 20 to be compensated for.

[0054] In the control device 70 of this embodiment, the DC link unit 20 is configured to be able to transmit and receive third DC power to and from the capacitor 30 connected to the DC link unit 20, and the control device 70 adjusts the first power pulsation so as to reduce third power pulsation, which is an AC component included in the third DC power, thereby reducing the power pulsation absorbed by the capacitor 30.

[0055] The control device 70 of the present embodiment adjusts the amplitude difference and phase difference between the second power pulsation and the first power pulsation, thereby compensating for the power pulsation occurring in the DC link unit 20.

[0056] The control device 70 of this embodiment adjusts the first power pulsation so that it approaches the second power pulsation, thereby compensating for the power pulsation occurring in the DC link unit 20.

[0057] In the control device 70 of the present embodiment, the device is a compensation circuit 42 that is connected to a power source and converts power from the power source into the first DC power. This allows the device that transmits the first DC power to the DC link unit 20 to compensate for power pulsation that occurs in the DC link unit 20.

[0058] In the control device 70 of the present embodiment, the device is an electric device that receives the first DC power, which makes it possible to compensate for power pulsation occurring in the DC link unit 20 without providing any special device.

[0059] In the control device 70 of this embodiment, the pulsation detection unit acquires information correlated with the second power pulsation from the grid-connected inverter 10. This makes it possible to compensate for the power pulsation occurring in the DC link unit 20 in accordance with the operation of the grid-connected inverter 10.

[0060] In the control device 70 of this embodiment, the pulsation detection unit includes a detection unit 80 that measures the second DC power, and a DC power measurement unit, an example of which is a detection circuit 81. This makes it possible to compensate for power pulsation occurring in the DC link unit 20 in accordance with the second power pulsation detected by the pulsation detection unit.

[0061] In the control device 70 of this embodiment, the second power pulsation pulsates at a frequency that is twice the power supply frequency of the system power supply 100. This makes it possible to compensate for the power pulsation contained in the system power supply 100.

[0062] In the control device 70 of this embodiment, the second power pulsation pulsates at a frequency that is an integral multiple of twice the power frequency of the system power supply 100 or an integral submultiple of twice the power frequency of the system power supply 100. This makes it possible to compensate for harmonic components contained in the system power supply 100 or power pulsation caused by equipment using frequency division control.

[0063] In the control device 70 of this embodiment, the electric equipment includes a rotating electric machine, which makes it possible to compensate for power pulsation occurring in the DC link unit 20 without impairing the function of the electric equipment.

[0064] In the control device 70 of this embodiment, the control device 70 adjusts the first power pulsation by adjusting the rotation speed or torque of the rotating electric machine, thereby compensating for the power pulsation occurring in the DC link unit 20 without impairing the functionality of the electric equipment.

[0065] The power systems 1, 2, and 3 of the present embodiment include a control device 70, one or more devices controlled by the control device 70, such as a compensation circuit 42 and an air conditioner 50, a DC link unit 20 to which the devices are connected, and a grid-connected inverter 10 configured to be connectable to a three-phase system power supply 100 and connected to the DC link unit 20. This makes it possible to extend the life of the power conditioner.

[0066] Although the embodiments have been described above, the technical scope of the present disclosure is not limited to the scope of the above-described embodiments. It is clear from the claims that combinations of two or more of the above-described embodiments, and various modifications or improvements to the above-described embodiments, are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0067] 1, 2, 3... Power system, 10... Grid-connected inverter, 11... Grid-connected inverter control board, 20... DC link unit, 30... Capacitor, 40... Solar panel, 41... DC / DC converter, 42... Compensation circuit, 50... Air conditioner, 60, 61... Single-phase load, 70... Control device, 71... Pulsation compensation control board, 80... Detection unit, 81... Detection circuit, 100... Grid power supply

Claims

1. A control device that controls one or more devices that transmit first DC power to a DC link unit or receive the first DC power from the DC link unit, the first DC power includes a first power ripple that is an AC component, the DC link unit is connected to the DC link unit and is configured to be able to transmit and receive second DC power to and from a grid-connected inverter that is connected to a three-phase grid power supply; The control device a pulsation detection unit that detects second power pulsation, which is an AC component included in the second DC power; The first power pulsation is adjusted in response to the second power pulsation detected by the pulsation detection unit. Control device.

2. the DC link unit is configured to be able to transmit and receive third DC power to and from a capacitor connected to the DC link unit; The control device adjusts the first power pulsation so as to reduce a third power pulsation, which is an AC component included in the third DC power. The control device according to claim 1 .

3. The control device adjusts the amplitude difference and the phase difference between the second power pulsation and the first power pulsation. The control device according to claim 1 .

4. The control device adjusts the first power pulsation to approximate the second power pulsation. The control device according to claim 1 .

5. The device is a compensation circuit connected to a power source and converts power from the power source into the first DC power. The control device according to claim 1 .

6. The device is an electric device that receives the first DC power. The control device according to claim 1 .

7. The pulsation detection unit acquires information correlated with the second power pulsation from the grid-connected inverter. The control device according to claim 1 .

8. The pulsation detection unit includes a DC power measurement unit that measures the second DC power. The control device according to claim 1 .

9. The second power pulsation pulsates at a frequency twice the power supply frequency of the system power supply. The control device according to claim 1 .

10. The second power pulsation pulsates at a frequency that is an integer multiple of twice the power supply frequency of the system power supply, or an integer fraction thereof. The control device according to claim 1 .

11. The electrical equipment includes a rotating electrical machine. The control device according to claim 6.

12. The control device adjusts the first power pulsation by adjusting the rotation speed or torque of the rotating electric machine. The control device according to claim 11.

13. A control device according to any one of claims 1 to 12; One or more devices controlled by the control device; a DC link unit to which the device is connected; a grid-connected inverter configured to be connectable to a three-phase power supply system and connected to the DC link unit; A power conditioner equipped with

14. 14. The power conditioner according to claim 13, wherein the heat pump system includes a refrigeration device as the equipment.

15. A control device according to any one of claims 1 to 12; one or more devices controlled by the control device; A power pulsation adjustment system with

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