Control devices, power conditioners, heat pump systems, and power pulsation control systems

Abstract

When a grid-connected inverter, which is connected to the DC link section and interconnected with a three-phase grid power supply, outputs three-phase unbalanced power, the power pulsation that occurs in the DC link section is compensated for by equipment installed in the DC link section. [Solution] The control device controls one or more devices that transmit first DC power to or receive first DC power from the DC link section. The first DC power includes a first power pulsation which is an AC component. The DC link section is configured to transmit and receive second DC power between the DC link section and a grid-connected inverter connected to the DC link section and a three-phase grid power supply. The control device includes a pulsation detection unit that detects a second power pulsation which is an AC component included in the second DC power, and adjusts the first power pulsation according to 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 adjustment system.

Background Art

[0002] For example, Non-Patent Document 1 discloses a self-excited reactive power compensation device (self-excited SVC) as a device for compensating three-phase imbalance and voltage fluctuations in a three-phase AC line. The self-excited SVC is composed of a voltage-type inverter, and three phases are formed using three single-phase inverters. And it is described that each of the three phases of the self-excited SVC is connected to each phase of the three-phase AC line to compensate for three-phase imbalance and voltage fluctuations.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a single-phase load is connected to a three-phase AC line, three-phase imbalance occurs. In the prior art, a compensation circuit was provided in the three-phase AC line to compensate for the three-phase imbalance. On the other hand, a method of outputting three-phase unbalanced power to a system connection inverter connected to the three-phase AC line to compensate for the three-phase imbalance caused by the single-phase load can be considered. In this case, power pulsations occur in the DC link section to which the system connection inverter is connected, so a technique for reducing the power pulsations is required.

[0005] This disclosure aims to compensate for power pulsations occurring in the DC link section when a grid-connected inverter, which is connected to a DC link section and interconnected with a three-phase grid power supply, outputs three-phase unbalanced power, by using equipment provided in the DC link section. [Means for solving the problem]

[0006] The control device in the first aspect is a control device that controls one or more devices that transmit first DC power to a DC link section or receive first DC power from the DC link section, wherein the first DC power includes a first power pulsation which is an AC component, the DC link section is configured to transmit and receive second DC power to and from a grid-connected inverter connected to the DC link section and connected to a three-phase grid power supply, and the control device includes a pulsation detection unit that detects a second power pulsation which is an AC component included in the second DC power, and adjusts the first power pulsation according to the second power pulsation detected by the pulsation detection unit. This makes it possible to compensate for power pulsation occurring in the DC link section. The control device in the second aspect is the control device in the first aspect, wherein the DC link section is configured to transmit and receive third DC power to and from a capacitor connected to the DC link section, and the control device adjusts the first power pulsation so that the third power pulsation, which is an AC component included in the third DC power, is reduced. This makes it possible to reduce the power pulsation absorbed by the capacitor. The control device in the third aspect is a control device in the first or second aspect that adjusts the amplitude difference and phase difference between the second power pulsation and the first power pulsation. This makes it possible to compensate for power pulsation occurring in the DC link section. The control device of the fourth aspect is a control device of any one of the first to third aspects, which adjusts the first power pulsation to approach the second power pulsation. This makes it possible to compensate for power pulsation occurring in the DC link section. The control device of the fifth aspect is a control device of any one of the first to fourth aspects, wherein the device is connected to a power supply and is a compensation circuit that converts the power of the power supply into the first DC power. This makes it possible to compensate for power pulsations occurring in the DC link section by a device that transmits the first DC power to the DC link section. The control device of the sixth aspect is a control device of any one of the first to fourth aspects, wherein the device is an electrical device that receives the first DC power. This makes it possible to compensate for power pulsation occurring in the DC link section without providing special equipment. The control device of the seventh aspect is a control device of any one of the first to sixth aspects, wherein the pulsation detection unit acquires information correlated with the second power pulsation from the grid-connected inverter. This makes it possible to compensate for power pulsation occurring in the DC link section in accordance with the operation of the grid-connected inverter. The control device according to the eighth aspect is a control device according to any one of the first to sixth aspects, wherein the pulsation detection unit includes a DC power measuring unit for measuring the second DC power. This makes it possible to compensate for the power pulsation occurring in the DC link section in accordance with the second power pulsation detected by the pulsation detection unit. The control device of the ninth aspect is a control device of any one of the first to eighth aspects, wherein the second power pulsation pulsates at a frequency twice that of the power supply frequency of the grid power supply. This makes it possible to compensate for power pulsation included in the grid power supply. The control device of the tenth aspect is a control device of any one of the first to eighth aspects, wherein the second power pulsation pulsates at a frequency that is an integer multiple or an integer fraction of twice the power frequency of the grid power supply. This makes it possible to compensate for harmonic components included in the grid power supply or power pulsation caused by equipment using frequency division control. The control device according to the eleventh aspect is the control device according to the sixth aspect, wherein the electrical equipment includes a rotating electric machine. This makes it possible to compensate for power pulsations occurring in the DC link section without impairing the function of the electrical equipment. The control device according to the twelfth aspect is the control device according to the eleventh aspect, wherein the control device adjusts the first power pulsation by adjusting the rotational speed or torque of the rotating electric machine. This makes it possible to compensate for power pulsation occurring in the DC link section without impairing the function of the electrical equipment. The power conditioner according to the 13th aspect comprises a control device according to any one of the first to 12 aspects, one or more devices controlled by the control device, a DC link section to which the devices are connected, and a grid-connected inverter configured to be connectable to a three-phase grid power supply and connected to the DC link section. This extends the lifespan of the power conditioner. The heat pump system of the 14th aspect is a power conditioner of the 13th aspect, which includes a refrigeration device as the equipment. The pulsating power adjustment system of the 15th aspect comprises a control device of any one of the first to 12th aspects and one or more devices controlled by the control device. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of a power system equipped with the control device of this embodiment. [Figure 2] This is a diagram illustrating the conventional technology. [Figure 3] This figure illustrates a method for adjusting power pulsation in this embodiment. [Figure 4] This diagram defines the amplitude -ΔP and phase α of power pulsation. [Figure 5] This is a diagram illustrating control pattern 1. [Figure 6] This is a diagram illustrating control pattern 2. [Figure 7] This is a diagram illustrating control pattern 3. [Figure 8] This is a diagram illustrating control pattern 4. [Figure 9] This is a diagram illustrating control pattern 5. [Figure 10] This is a diagram illustrating control pattern 6. [Figure 11] This is a diagram illustrating control pattern 7. [Figure 12] This is an example of the output waveform of a single-phase frequency divider controlled thyristor. [Figure 13] This figure shows an example of a detailed circuit diagram of this embodiment. [Figure 14] The following figures show other examples of compensation circuits. (a) is an example of a buck active buffer circuit, and (b) is an example of a series voltage injector. [Modes for carrying out the invention]

[0008] The embodiments will be described in detail below with reference to the attached drawings. Figure 1 shows an example of a power system equipped with the control device of this embodiment. Power system 1 comprises a grid-connected inverter 10, a DC link section 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. Power system 1 is connected to a three-phase grid power supply 100. The three-phase grid power supply 100 is, for example, 200V, 50Hz. In the diagram, the grid-connected inverter 10 is denoted as grid-connected INV, and the DC / DC converter 41 is denoted as DC / DC. In the diagram, the area to the right of the grid-connected inverter 10 is sometimes referred to as the AC line, and the area to the left of the grid-connected inverter 10 is sometimes referred to as the DC line.

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

[0010] The grid-connected inverter 10 performs forward power flow operation, reverse power flow operation, and disconnection operation. In forward power flow operation, AC power is converted to DC power and supplied from the three-phase grid power supply 100 to the DC link section 20. In reverse power flow operation, DC power is converted to three-phase AC power and supplied from the DC link section 20 to the three-phase grid power supply 100. The grid-connected inverter 10 is an inverter that can supply power in both directions. In reverse power flow operation and forward power flow operation, the AC line side and the DC line side operate in parallel via the grid-connected inverter 10. Disconnection operation is an operation that does not perform either reverse power flow operation (converting DC power to AC power) or forward power flow operation (converting AC power to DC power). In disconnection operation, the AC line side and the DC line side operate separately. The grid-connected inverter 10 connects an AC power grid (in this case, a three-phase grid power supply) with a DC power grid.

[0011] The DC link section 20 is a DC current path, with one of the two current paths being positive (+) and the other negative (-). The DC link section 20 is capable of transmitting and receiving DC power to and from the grid-connected inverter 10. The capacitor 30 is connected between the two current paths of the DC link section 20 and adjusts the pulsations that occur 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 photoelectric effect. The DC / DC converter 41 is installed between the solar panel 40 and the DC link section 20, and converts the DC voltage output by the solar panel 40 into the DC voltage of the DC link section 20. The compensation circuit 42 compensates for power pulsations that occur in the DC link section 20.

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

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

[0015] The air conditioner 50 consumes DC power supplied from the DC link section 20. The air conditioner 50 includes a rotating electric machine, and compensates for power pulsations occurring in the DC link section 20 by adjusting the rotational speed or torque of the rotating electric machine. Instead of the air conditioner 50, a refrigeration system or a ventilation system may be used. Refrigeration systems include, for example, air conditioners, water heaters, chiller units, and cooling systems that cool the air inside a storage area. The air conditioner may be a cooling-only unit, a heating-only unit, or an air conditioner that switches between cooling and heating. Cooling systems cool the air inside refrigerators, freezers, containers, etc. A single-phase load 60 refers to electrical equipment that operates using AC power, such as lights and heaters. The control device 70 controls the compensation circuit 42 and the air conditioner 50 to compensate for power pulsations occurring in the DC link section 20. In the example shown in Figure 1, the control device 70 is independent, but it may be integrated with the compensation circuit 42 and the air conditioner 50. The power pulsation adjustment system is comprised of a control device 70, a DC / DC converter 41, a compensation circuit 42, and an air conditioner 50.

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

[0017] In Figure 1, the names of the power supplies and the direction in which power is supplied to each device and the grid-connected inverter 10 are defined. In Figure 1, the direction in which power is supplied is indicated by an arrow. The power supplied by the solar panel 40 is converted to power P via the DC / DC converter 41 and the compensation circuit 42. PV This is how it is written. Power P PV The direction in which current is supplied from the solar panel 40 to the DC link section 20 is defined as positive (+). The power supplied from the DC link section 20 to the air conditioner 50 is P load This is how it is written. Power P loadThe direction from the DC link section 20 side to the air conditioner 50 side is defined as positive (+). The power P PV and the power P load are an example of the first DC power. The power transmitted and received between the DC link section 20 and the grid-connected inverter 10 is denoted as P DC . The power P DC has the direction from the DC link section 20 side to the grid-connected inverter 10 side defined as positive (+). The power P DC is an example of the second DC power. The grid-connected inverter 10 outputs three-phase power of the u-phase, v-phase, and w-phase. The power of the u-phase is P u , the power of the v-phase is P v , and the power of the w-phase is P w . The power P u , P v and P w have the direction from the grid-connected inverter 10 side to the three-phase grid power source 100 side defined as positive (+).

[0018] FIG. 2 is a diagram for explaining the prior art. The grid-connected inverter 10 connected to the three-phase grid power source 100 outputs three-phase balanced power to the 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 is generated between the single-phase load 60 and the three-phase grid power source 100. In the state of three-phase unbalanced power, power cannot be supplied to the three-phase grid power source 100 side, so a compensation circuit is connected to compensate the three-phase unbalanced power into three-phase balanced power and supply power to the three-phase grid power source 100 side. In this case, since the grid-connected inverter 10 outputs three-phase balanced power, no power pulsation occurs in the DC link section 20.

[0019] Figure 3 illustrates a method for adjusting power pulsation in this embodiment. The grid-connected inverter 10 outputs three-phase unbalanced power to the 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, power pulsation occurs in the DC link section 20 because the grid-connected inverter 10 outputs three-phase unbalanced power. Power pulsation in the DC link section 20 may shorten the lifespan of equipment and capacitors 30 connected to the DC link section, so it is necessary to adjust the power pulsation. In this embodiment, power pulsation is adjusted by pulsating the power of the DC link section 20 in order to cancel out the power pulsation occurring in the DC link section 20.

[0020] Next, we will explain how to adjust the power pulsation that occurs in the DC link section 20. Assume that the grid-connected inverter 10 is autonomously or consequently outputting three-phase unbalanced power. 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 These are defined by equations (1), (2), and (3), respectively. Power P of the u-phase u The power is expressed by equation (1). The amplitude is 2P, which is the smallest among the three phases. θ is the phase of the AC power. Power P of the v phase v It is assumed that it is expressed by equation (2). The amplitude is 2P greater than that of the u-phase. α The power of the w phase is significantly larger, and the phase is shifted by 2 / 3π (120°). w It is assumed that it is expressed by equation (3). The amplitude is 2P greater than that of the u-phase. β It is only slightly larger, and the phase is shifted by 4 / 3π (240°). The actual power consumption of each component 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). Figure 4 is a diagram defining the amplitude -ΔP and phase α of the power pulsation. As shown in Figure 4, the difference in power between the v-phase and w-phase compared to 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 we let the amplitude of the component obtained by combining these two vectors be -ΔP and the phase be α, then equation (4) can be rewritten as equation (5). In equation (5), {-ΔPcos(2θ-α)} is the power pulsation.

[0023]

number

[0024] The power expressed in equation (5) is the power P supplied from the DC link section 20 to the grid-connected inverter 10. DC This can also be said. Therefore, power P DC This is expressed by equation (6). In other words, the three-phase unbalanced power output by the grid-connected inverter 10 generates power pulsations in the DC link section 20, which are AC components represented by {-ΔPcos(2θ-α)}. The power pulsations generated in the DC link section 20 are an example of the second power pulsation.

[0025]

number

[0026] Power pulsations occurring in the DC link section 20 are compensated by controlling the power of the equipment connected to the DC link section 20. Specifically, power pulsations with a phase inverted by 180° are generated to cancel out the power pulsations occurring in the DC link section 20. Two methods are possible for canceling out power pulsations: compensation by the compensation circuit 42, and absorption by the load of the air conditioner 50.

[0027] When compensation is performed by the compensation circuit 42, the power P output by the compensation circuit 42 PV Control it as shown in equation (7). P PV_dc This is the DC power generated by the solar panel 40, and is the normal component. To this normal component, an AC component is added, in which the amplitude information and phase information of the power pulsation expressed by equation (6) are matched. PV_ac is the amplitude of the AC component, and (2θ-α) is the phase of the AC component. 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 This is determined by MPPT (Maximum PowerPoint Control) control.

[0028] When power pulsation is compensated for by the load of the air conditioner 50, the power P supplied from the DC link section 20 to the air conditioner 50 load Control it as shown in equation (8). Power P load This can also be said to be the power consumed by the air conditioner 50. load_dc This is the DC power consumed by the air conditioner 50, and is the normal component. To this normal component, an AC component is added, in which the amplitude information and phase information of the power pulsation expressed by equation (6) are matched. P load_ac is the amplitude of the AC component, and (2θ-α) is the phase of the AC component. 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 This 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 section 20. Therefore, the power P consumed by the air conditioner 50 is large. load Even if it pulsates, the function of the air conditioner 50 will not be impaired.

[0029]

number

[0030] The cases in which power pulsations occurring in the DC link section 20 are compensated by the compensation circuit 42 alone and by the air conditioner 50 alone have been explained. In addition, there is a case in which power pulsations occurring in the DC link section 20 are compensated by both the compensation circuit 42 and the air conditioner 50. In this case, the power P output by the compensation circuit 42 is such that the energy balance is expressed in equation (9). PV and the power P consumed by the air conditioner 50 load It controls the power P. In equation (9), load The reason there is a minus (-) sign before it is because of power P load This is because the direction in which the DC current is supplied from the DC link section 20 to the air conditioner 50 is defined as positive (+).

[0031] When the power pulsation generated in the DC link section 20 is compensated only by the compensation circuit 42, the amplitude of the AC component is expressed by equation (10) based on the energy balance. When the power pulsation generated in the DC link section 20 is compensated only by the air conditioner 50, the amplitude of the AC component is expressed by equation (11). When the power pulsation generated in the DC link section 20 is compensated by both the compensation circuit 42 and the air conditioner 50, the amplitude of the AC component is expressed by equation (12). Thus, the amplitude P of the power pulsation generated by the compensation circuit 42 PV_ac and the amplitude P of the power pulsation consumed by the air conditioner 50 load_ac By matching the sum of these values ​​to the amplitude -ΔP of the power pulsation occurring in the DC link section 20, the power pulsation occurring in the DC link section 20 is canceled out.

[0032]

number

[0033] DC power is transmitted and received between the DC link section 20 and the capacitor 30. The capacitor 30 absorbs power pulsations, which are AC components included in the DC power. If the power pulsations generated in the DC link section 20 are large, the required capacity of the capacitor 30 will increase. In this embodiment, the power pulsations included in the DC power transmitted and received between the DC link section 20 and the capacitor 30 are compensated by the compensation circuit 42 and the air conditioner 50. The DC power transmitted and received between the DC link section 20 and the capacitor 30 is an example of third DC power. Also, the power pulsations included in the DC power transmitted and received between the DC link section 20 and the capacitor 30 are an example of third power pulsations. In other words, the control device 70 adjusts the first power pulsations so that the third power pulsations, which are AC components included in the third DC power, are reduced. More specifically, the control device 70 adjusts the first power pulsation so that 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, is reduced. This reduces the power pulsation absorbed by the capacitor 30, and thus the capacitance of the capacitor 30 can be reduced.

[0034] (Example 1) In Example 1, power pulsations occurring in the DC link section 20 are compensated based on the power information output by the grid-connected inverter 10. Figure 5 is a diagram illustrating control pattern 1. The grid-connected inverter 10 controls the output power P of the grid-connected inverter 10. u , P v and P w Information is transmitted to the control device 70. Based on the information received from the grid-connected inverter 10, the control device 70 calculates the power pulsation occurring in the DC link section 20. Output power P of the grid-connected inverter 10 u , P v and P wThe information in question can be described as information correlated with the power pulsation occurring in the DC link section 20. The control device 70 has the function of a pulsation detection unit. In other words, the pulsation detection unit acquires information correlated with the second power pulsation from the grid-connected inverter 10.

[0035] In control pattern 1, the control device 70 issues commands to the air conditioner 50 regarding amplitude and phase based on the calculation results of power pulsation, P load_ac * and α * The air conditioner 50 transmits a power pulsation P based on the received command. load_ac cos(2θ-α) is the normal component of DC power P load_dc In addition, it consumes power. This compensates for power pulsations that occur in the DC link section 20.

[0036] Figure 6 is a diagram illustrating control pattern 2. In control pattern 1, the control device 70 transmitted commands regarding amplitude and phase to the air conditioner 50. In contrast, in control pattern 2, the control device 70, based on the calculation results of power pulsation, transmits commands regarding amplitude and phase to the compensation circuit 42, P PV_ac * and α * The power pulsation P is transmitted based on the received command. The compensation circuit 42 controls the power pulsation P PV_ac cos(2θ-α) is the DC power P generated by the solar panel 40. PV_dc In addition, it outputs power. This compensates for power pulsations that occur in the DC link section 20.

[0037] Figure 7 illustrates control pattern 3. In control pattern 3, the control device 70 transmits commands regarding amplitude and phase to both the air conditioner 50 and the compensation circuit 42 based on the calculation results of power pulsation. At this time, the control device 70 transmits the amplitude P of the power pulsation consumed by the air conditioner 50. load_ac and the amplitude P of the power pulsation generated by the compensation circuit 42 PV_ac Commands are sent to the air conditioner 50 and the compensation circuit 42 so that equation (12) is satisfied. This compensates for power pulsations occurring in the DC link section 20.

[0038] (Example 2) In Example 1, power pulsations occurring in the DC link section 20 were compensated based on information about the power output of the grid-connected inverter 10. In contrast, in Example 2, power pulsations occurring in the DC link section 20 are directly detected and compensated for. Figure 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. The other components are the same as those in the power system 1 shown in Figure 5, so the same reference numerals are used and their explanation is 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 power P measured by the detection unit 80 is measured. For example, a fluxgate current sensor can be used as the detection unit 80. The control device 70 controls the power P measured by the detection unit 80. DC The information is subjected to a Fourier transform to identify 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, the Fourier transform is performed focusing on that frequency. The grid power also contains pulsations of harmonic components that are integer multiples of twice the power supply frequency. In the control device 70 of Example 2, power pulsations with frequencies that are integer multiples of twice the power supply frequency can also be compensated by changing the frequency that is the focus when performing the Fourier transform.

[0040] In control pattern 4, the control device 70 issues commands to the air conditioner 50 regarding amplitude and phase, P, 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 a power pulsation P based on the received command. load_ac cos(2θ-α) is the normal component of DC power P load_dc In addition, it consumes power. This compensates for power pulsations that occur in the DC link section 20.

[0041] Figure 9 is a diagram illustrating control pattern 5. In control pattern 5, the control device 70 issues commands to the compensation circuit 42 regarding amplitude and phase based on information about the amplitude and phase of the power pulsation obtained by the Fourier transform, P PV_ac * and α* The power pulsation P is transmitted based on the received command. The compensation circuit 42 controls the power pulsation P PV_ac cos(2θ-α) is the DC power P generated by the solar panel 40. PV_dc In addition, it outputs power. This compensates for power pulsations that occur in the DC link section 20.

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

[0043] (Modified version of Example 2) When a device utilizing frequency division control is used as a single-phase load 60 connected to a three-phase AC line, power pulsations of a frequency other than twice the power supply frequency occur in the DC link section 20. Figure 11 is a diagram illustrating control pattern 7. In the power system 3, one of the single-phase loads 60 is a single-phase load 61 that utilizes frequency division control.

[0044] The frequency division control method controls the ratio of energizing time within a certain 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%, the thyristor is energized for the duration of three cycles of the AC power supply, and de-energized for the duration of one cycle. When the output is 50%, the thyristor alternates between energizing and de-energizing every cycle. When the output is 25%, the thyristor is energized for the duration of one cycle of the AC power supply, and de-energized for the duration of three cycles. When the output is 75% and 25%, power fluctuations occur at a frequency four times that of the AC power supply. When the output is 50%, power fluctuations occur at a frequency twice that of the AC power supply. In other words, when the output is 75% and 25%, power fluctuations occur at a frequency one-quarter of the power supply frequency, and when the output is 50%, power fluctuations occur at a frequency one-half of the power supply frequency. In such cases, power pulsations with a frequency of 1 / 2 or 1 / 4 of the power supply frequency occur in the DC link section 20.

[0045] In control pattern 7, similar to control pattern 4, 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 control device 70 measures the power P measured by the detection unit 80. DC The information is Fourier transformed to identify information regarding the amplitude and phase of power pulsations.

[0046] Based on the information regarding the amplitude and phase of the power pulsation obtained by the Fourier transform, the control device 70 issues commands to the air conditioner 50 regarding the amplitude and phase, P load_ac * and α * The air conditioner 50 transmits a power pulsation P based on the received command. load_ac cos(2θ-α) is the normal component of DC power P load_dc In addition to this, it consumes power. This compensates for power pulsations that occur in the DC link section 20, which pulsate at a frequency that is an integer fraction of the power supply frequency of the grid power supply. Here, a method for compensating for power pulsations using the air conditioner 50 has been described, but is not limited to this. Power pulsations may also be compensated by the compensation circuit 42, or by both the air conditioner 50 and the compensation circuit 42.

[0047] Figure 13 shows an example of a detailed circuit diagram of this embodiment. The circuit diagram in Figure 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 the grid-connected INV control board.

[0048] A grid-connected inverter 10 can be exemplified by one that uses IGBTs (insulated-gate bipolar transistors) as switching elements. The grid-connected inverter control board 11 transmits control signals to the grid-connected inverter 10 and controls the three-phase power output by the grid-connected inverter 10. The control signals are, for example, gate signals that control IGBTs. The grid-connected inverter control board 11 also transmits information regarding the output power of the grid-connected inverter 10 to the pulsation compensation control board 71. The grid-connected inverter control board 11 is composed of, for example, a CPU, RAM, ROM, etc. The detection unit 80 measures the DC power of the DC link unit 20. The detection circuit 81 amplifies the signal related to the DC power measured by the detection unit 80 and transmits it to the pulsation compensation control board 71.

[0049] The compensation circuit 42 generates power pulsations in the DC link section 20. An example of the compensation circuit 42 is a boost-type active buffer circuit. A boost-type active buffer circuit consists of a boost chopper and a buffer capacitor. As the switching element of the boost chopper, for example, a MOSFET, HEMT, bipolar transistor, IGBT, etc., can be used.

[0050] The pulsation compensation control board 71 is an example of the control device 70. The pulsation compensation control board 71 is composed of, for example, a CPU, RAM, ROM, etc. Based on the information regarding the output power of the grid-connected inverter 10 received from the grid-connected inverter control board 11, the pulsation compensation control board 71 calculates the power pulsation occurring in the DC link section 20. Based on the calculated power pulsation, the pulsation compensation control board 71 transmits control signals as commands to the compensation circuit 42 and the air conditioner 50. The control signal transmitted to the compensation circuit 42 is, for example, a gate signal to control 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 DC power signal received from the detection circuit 81 to identify information regarding the amplitude and phase of power pulsations occurring in the DC link section 20. Based on the identified information regarding the amplitude and phase of power pulsations, 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 Figure 13, the compensation circuit 42 was a boost-type active buffer circuit. However, the compensation circuit 42 is not limited to this. Figure 14 shows other examples of the compensation circuit 42. The compensation circuit 42 shown in Figure 14(a) is a buck-type active buffer circuit. A buck-type active buffer circuit consists of a buck chopper and a buffer capacitor. For example, a MOSFET is used as the switching element of the buck chopper. The compensation circuit 42 shown in Figure 14(b) is a series voltage injector (SVI). A series voltage injector consists of an H-bridge circuit with an LC output filter and a flying buffer capacitor. For example, a MOSFET is used as the switching element of the H-bridge circuit. Three types of compensation circuits 42 have been given as examples: a boost-type active buffer circuit, a buck-type active buffer circuit, and a series voltage injector, but the compensation circuit 42 is not limited to these. Compensation circuits 42 may be other types of compensation circuits.

[0053] (Effects of the embodiment) The control device 70 in this embodiment controls one or more devices, such as a compensation circuit 42 and an air conditioner 50, which transmit first DC power to or receive said first DC power from the DC link unit 20. The first DC power includes a first power pulsation, which is an AC component. The DC link unit 20 is configured to transmit and receive second DC power between the DC link unit 20 and a grid-connected inverter 10 connected to the DC link unit 20 and a three-phase grid power supply 100. The control device 70 includes a pulsation compensation control board 71, a detection unit 80, and a pulsation detection unit, such as a detection circuit 81, which detect the second power pulsation, which is an AC component included in the second DC power. The control device 70 adjusts the first power pulsation according to the second power pulsation detected by the pulsation detection unit. This makes it possible to compensate for power pulsation occurring in the DC link unit 20.

[0054] In the control device 70 of this embodiment, the DC link section 20 is configured to transmit and receive third DC power to and from a capacitor 30 connected to the DC link section 20, and the control device 70 adjusts the first power pulsation so that the third power pulsation, which is an AC component included in the third DC power, is reduced. This makes it possible to reduce the power pulsation absorbed by the capacitor 30.

[0055] The control device 70 of this embodiment adjusts the amplitude difference and phase difference between the second power pulsation and the first power pulsation. This makes it possible to compensate for power pulsations that occur in the DC link section 20.

[0056] The control device 70 of this embodiment adjusts the first power pulsation to approach the second power pulsation. This makes it possible to compensate for the power pulsation that occurs in the DC link section 20.

[0057] In the control device 70 of this embodiment, the device is a compensation circuit 42 connected to a power supply that converts the power of the power supply into the first DC power. This allows the device that supplies the first DC power to the DC link section 20 to compensate for power pulsations occurring in the DC link section 20.

[0058] In the control device 70 of this embodiment, the device is an electrical device that receives the first DC power. This makes it possible to compensate for power pulsations occurring in the DC link section 20 without providing any special equipment.

[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 power pulsations occurring in the DC link section 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 DC power measurement unit, such as a detection unit 80 and a detection circuit 81, for measuring the second DC power. This makes it possible to compensate for the power pulsation generated 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 twice that of the power supply frequency of the grid power supply 100. This makes it possible to compensate for the power pulsation included in the grid power supply 100.

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

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

[0064] In the control device 70 of this embodiment, the control device 70 adjusts the first power pulsation by adjusting the rotational speed or torque of the rotating electric machine. This makes it possible to compensate for power pulsation occurring in the DC link section 20 without impairing the function of the electrical equipment.

[0065] The power systems 1, 2, and 3 of this 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 section 20 to which the devices are connected, and a grid-connected inverter 10 that is connected to the DC link section 20 and is configured to be connectable to a three-phase grid power supply 100. This makes it possible to extend the lifespan of the power conditioner.

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

[0067] 1, 2, 3…Power system, 10…Grid-connected inverter, 11…Grid-connected inverter control board, 20…DC link section, 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 for controlling one or more devices that transmit first DC power to a DC link section or receive said first DC power from said DC link section, The first DC power includes a first power pulsation which is an AC component. The DC link section is configured to transmit and receive second DC power between itself and a grid-connected inverter connected to the DC link section and a three-phase grid power supply. The control device is The system includes a pulsation detection unit that detects a second power pulsation, which is an AC component included in the second DC power, The first power pulsation is adjusted according to the second power pulsation detected by the pulsation detection unit. Control device.

2. The DC link section is configured to transmit and receive third DC power with a capacitor connected to the DC link section. The control device adjusts the first power pulsation so that the third power pulsation, which is an AC component included in the third DC power, is reduced. The control device according to claim 1.

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

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

6. The aforementioned device is an electrical 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 measuring unit for measuring the second DC power. The control device according to claim 1.

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

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

12. The control device adjusts the first power pulsation by adjusting the rotational 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, The control device controls one or more devices, The DC link section to which the aforementioned equipment is connected, A grid-connected inverter is configured to be connectable to a three-phase grid power supply and is connected to the DC link section. A power conditioner equipped with [feature].

14. A heat pump system comprising a refrigeration device as the equipment in the power conditioner according to claim 13.

15. A control device according to any one of claims 1 to 12, The control device controls one or more devices and A power pulsation regulation system equipped with a power pulsation control system.

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