Devices with built-in active filters.

Abstract

A device with a built-in active filter has the built-in active filter device (4) and is connected to an AC power supply (3), wherein the active filter device (4) is configured so as to operate on the basis of a detection value detected by a load information detection unit (5) for detecting load information of the AC power supply (3) at the outside of the device with the built-in active filter.

Description

Device incorporating an active filter

[0001] The present invention relates to a device incorporating an active filter.

[0002] In an air conditioner or the like, an active filter device may be provided to prevent harmonic current from flowing into a power system (for example, a power system including a commercial power supply) (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2016-116330

[0004] However, in the power system to which an air conditioner is connected, a load device other than the air conditioner (for example, a device having an inverter circuit or the like. As an example, an elevator or the like) may also be connected, and a load device other than the air conditioner may be a source of harmonic current. In that case, it is not sufficient to only take measures against the harmonic current of the air conditioner, and it is desirable to take measures against the harmonic current including other devices. Also, improvement of the fundamental power factor is required from the viewpoints of reducing equipment capacity and energy saving.

[0005] An object of the present invention is to enable an active filter device to operate in an active filter incorporated device including other load devices different from the active filter incorporated device.

[0006] To solve the above problems, a first aspect is an active filter incorporated device incorporating an active filter device (4) and connected to an AC power supply (3), wherein the active filter device (4) is configured to operate based on a detection value of a load information detection unit (5) that detects load information of the AC power supply (3) outside the active filter incorporated device.

[0007] In this configuration, the active filter device (4) functions based on the load information of the AC power supply (3) in the power system outside the active filter incorporated device.

[0008] Furthermore, the second embodiment is an active filter-integrated device characterized in that, in the first embodiment, the active filter device (4) outputs a current based on the detected value to reduce harmonic currents in the AC power supply (3) and improve the fundamental wave power factor in the AC power supply (3).

[0009] In this configuration, the active filter device (4) performs at least one of the following: a reduction in harmonic currents and an improvement in the fundamental wave power factor.

[0010] Furthermore, the third embodiment is an active filter-integrated device characterized in that, in the first embodiment, the operation of the active filter device (4) is controlled by a controller (43) mounted on the active filter-integrated device, and the controller (43) determines the magnitude of the current (Ic) output by the active filter device (4) using a current value (iq2*) corresponding to the reactive current in another load device (20) connected to the AC power supply (3) and the current values ​​(ir1, it1) of the current flowing from the AC power supply (3) to the active filter-integrated device.

[0011] In this configuration, the power factor is improved based on the reactive current in other load devices (20). Therefore, when other loads are connected to the power system along with the air conditioning system, it becomes possible to improve the power factor without increasing the capacity of the active filter device.

[0012] Furthermore, the fourth embodiment is an active filter-integrated device characterized in that, in the third embodiment, the active filter device (4) uses only the fundamental wave component of the reactive current as the current value (iq2*) corresponding to the reactive current.

[0013] This configuration is suitable for improving the power factor in a configuration where the harmonic currents output by other load devices (20) are small or nonexistent.

[0014] Furthermore, the fifth embodiment is an active filter-integrated device characterized in that, in the first embodiment, the AC power supply (3) is connected in parallel with the active filter-integrated device and is connected to a phase-shifting device (200) that controls the reactive power in the AC power supply (3), and the active filter device (4) operates based on at least one of the reactive power of the AC power supply (3) and the power factor of the power supply so as to improve the leading power factor by controlling the reactive power of the phase-shifting device (200).

[0015] In this configuration, when the active filter device (4) is operating, the actual power factor of the power source lags behind the target power factor, in contrast to the phase-shifting equipment (200). Therefore, here, the issue of the actual power factor of the power source leading the target power factor due to the control of the reactive power of the phase-shifting equipment (200) is rectified by controlling the operation of the active filter device (4). This easily rectifies the phenomenon of the actual power factor leading due to the phase-shifting equipment (200), enabling appropriate compensation of the actual power factor and improvement of the fundamental wave power factor. Consequently, the possibility of increased power loss in the AC power source (3) power system and the occurrence of problems such as unnecessary voltage increases in the system can be suppressed.

[0016] Furthermore, the sixth embodiment is an active filter-integrated device characterized in that, in the first embodiment, the magnitude of the current (Ic) output by the active filter device (4) is determined using the current value (iq) corresponding to the reactive current of the load device (10) and phase-shifting equipment (200) other than the active filter-integrated device connected to the AC power supply (3), and the current values ​​(ir1, it1) of the current flowing from the AC power supply (3) to the load device (10).

[0017] In this configuration, the reactive currents of load devices and phase-shifting equipment other than those with built-in active filters are identified, and a current (Ic) is supplied to compensate for them.

[0018] Furthermore, the seventh embodiment is an active filter-integrated device characterized in that, in any of the first to sixth embodiments, the load information detection unit (5) is configured to detect current values ​​(Irs, Its), and the method of transmitting the detected current values ​​(Irs, Its) is wireless.

[0019] In this configuration, the adoption of a wireless system eliminates the need for wiring.

[0020] Furthermore, the eighth embodiment is an active filter-integrated device characterized in that, in any of the first to seventh embodiments, the load information detection unit (5) operates in a power-free manner.

[0021] This configuration eliminates the need for wiring by employing a power-free system.

[0022] Furthermore, the ninth embodiment is an active filter-integrated device characterized in that, in any of the first to eighth embodiments, the load information detection unit (5) is provided with current detectors (4a, 4b, 4c) for detecting current values ​​(Irs, Iss, Its), corresponding to each phase (R, S, T) of the AC power supply (3).

[0023] In this configuration, the current value can be reliably detected even if the load devices (1,2) are equipment that operates on single-phase AC.

[0024] According to the first embodiment, in an active filter-integrated device that incorporates an active filter device, the active filter device can operate on other load devices connected to an AC power supply that are different from the active filter-integrated device.

[0025] Furthermore, according to the second embodiment, in a power system in which multiple load devices are connected, it becomes possible to reduce harmonic currents and improve the fundamental wave power factor, or at least one of the above.

[0026] Furthermore, according to the third embodiment, it becomes possible to improve the power factor while suppressing an increase in the size of the active filter device.

[0027] Furthermore, according to the fourth embodiment, it becomes possible to generate a compensation current suitable for loads connected to a power system together with active filter equipment, where harmonic current countermeasures are not required.

[0028] Furthermore, according to the fifth embodiment, the phenomenon in which the actual power factor becomes a leading power factor due to the phase-shifting equipment can be easily improved, and appropriate compensation for the actual power factor and improvement of the fundamental wave power factor can be achieved. Accordingly, the possibility of increased power loss in AC power systems and the occurrence of problems such as unnecessary increases in the voltage of said systems can be suppressed.

[0029] Furthermore, according to the sixth embodiment, it becomes possible to improve the power factor in buildings and the like that equipped with phase-shifting equipment.

[0030] Furthermore, according to the seventh and eighth embodiments, the installation of the equipment becomes easier.

[0031] Furthermore, according to the ninth embodiment, the above effect can be reliably obtained even if the load device is a device that operates on single-phase AC.

[0032] Figure 1 is a block diagram of an air conditioning system according to Embodiment 1. Figure 2 is a block diagram of an example of a controller according to Embodiment 1. Figure 3 is a block diagram of an air conditioning system according to Embodiment 2. Figure 4 is a block diagram of an air conditioning system according to Embodiment 3. Figure 5 is a block diagram of an air conditioning system according to Embodiment 4. Figure 6 is a block diagram of a controller according to Embodiment 4. Figure 7 is a block diagram of an air conditioning system according to Embodiment 5. Figure 8 is a block diagram of an air conditioning system according to a modified example of Embodiment 5. Figure 9 is a block diagram of an air conditioning system according to Embodiment 6. Figure 10 schematically shows the configuration of the phase adjustment equipment. Figure 11 is a block diagram of the configuration of a power supply power factor control system according to Embodiment 7. Figure 12 is a block diagram of the configuration of a phase adjustment equipment controller according to Embodiment 7. Figure 13 is a conceptual diagram of a switching combination table of phase adjustment equipment. Figure 14 is a diagram showing the state in Embodiment 7 where compensation by the active filter device is not performed and the state where compensation by the active filter device is performed. Figure 15 is a block diagram of the configuration of an active filter controller according to Embodiment 7.

[0033] Embodiments of the present invention will be described below with reference to the drawings. The following embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or its uses.

[0034] <Embodiment 1 of the Invention> Figure 1 is a block diagram showing an air conditioning system (100) according to Embodiment 1 of the present invention. In this example, the air conditioning system (100) comprises an air conditioning device (11) and an active filter device (4). The air conditioning system (100) is installed in apartments, factories, buildings, detached houses, etc. (hereinafter referred to as "buildings, etc.") and the air conditioning device (11) provides indoor air conditioning (cooling and heating).

[0035] The building where the air conditioning system (11) is installed is supplied with power from a power grid that includes an AC power source (3). In this example, the AC power source (3) is a three-phase AC power source (for example, a three-phase commercial power source) that distributes power to multiple load devices (described later). The building is also equipped with a distribution board (60) that is connected to the AC power source (3) and receives AC power from the AC power source (3). The distribution board (60) has multiple circuit breakers, and through each breaker, it distributes the AC power from the AC power source (3) to multiple devices. In this example, the air conditioning system (11) is connected to one of these circuit breakers. The air conditioning system (11) operates using the AC power supplied via the distribution board (60). In other words, the air conditioning system (100) is an example of an active filter-equipped device that incorporates an active filter device (4) and is connected to the AC power source (3). Furthermore, devices with built-in active filters may also include elevators, fans, pumps, escalators, and lighting systems powered by three-phase power, all of which are installed in buildings.

[0036] In addition to the air conditioning system (11), a load device (2) is also connected to the distribution board (60). In this example, the load device (2) is a device equipped with a circuit that can be a source of harmonic currents, such as an inverter circuit (referred to as a harmonic generating load device). Examples of load devices (2) include elevators, fans, pumps, escalators, lighting driven by a three-phase power supply, and other air conditioning systems separate from the air conditioning system (11) that do not have harmonic countermeasures such as active filters installed in the building.

[0037] <Air Conditioning System (11)> The air conditioning system (11) includes a refrigerant circuit with a compressor (not shown), and a power converter (1), and incorporates an active filter device (4). The power converter (1) is a load connected to an AC power source (3), and is an example of the harmonic generating load. The power converter (1) is connected to the AC power source (3) via a distribution board (60). This power converter (1) has a converter circuit and an inverter circuit (neither of which are shown). The AC power supplied to the power converter (1) is converted by this power converter (1) into AC power having a desired frequency and voltage, and supplied to the compressor (more specifically, the motor provided in the compressor). As a result, the compressor operates and the refrigerant circuit functions, and as a result, the indoor air is conditioned.

[0038] In the air conditioning system (11), harmonic currents may be generated when the power converter (1) or the compressor motor is in operation. These harmonic currents may flow out to the AC power source (3) through the current path that supplies power from the distribution board (60) to the air conditioning system (11). Generally, the level of such harmonic currents flowing out to the AC power source (3) is regulated, so the air conditioning system (100) uses an active filter device (4) to reduce the amount of harmonic currents that flow out. Furthermore, from the perspective of equipment capacity and energy saving, improvement of the fundamental wave power factor at the power distribution and receiving ends is required, and the active filter device (4) in this embodiment also has a function to improve the fundamental wave power factor. The configuration of the active filter device (4) will be described below.

[0039] <Active Filter Device (4)> The active filter device (4) is incorporated into the air conditioning system (11) and has the function of canceling out the harmonic currents flowing out from the harmonic generating load. That is, the active filter device (4) flows a current (compensation current) so that the current in the current path (hereinafter also called the power receiving path) connecting the AC power supply (3) and the distribution board (60) approaches a sine wave. More specifically, it detects the harmonic currents appearing in the power receiving path and generates a compensation current that is in the opposite phase to the detected harmonic currents and supplies it to the power receiving path of the air conditioning system (11) (power receiving path (12) in Figure 1).

[0040] The harmonic currents generated in the air conditioning system (11) are thought to be largest when the load on the air conditioning system (11) is greatest (for example, at maximum cooling output). Therefore, the capacity (magnitude of power that can be generated) of the active filter device (4) is set assuming the harmonic currents at the maximum load of the air conditioning system (11). Generally, air conditioning systems (11) are used more often at intermediate loads than at maximum loads, so if the active filter device (4) with its capacity set in this way is used solely for countermeasures against the harmonic currents of the air conditioning system (11) during operation, it is thought that there will be a lot of periods where the capacity is surplus.

[0041] Furthermore, this active filter device (4) has a function to improve the fundamental wave power factor. In this example, the active filter device (4) is configured to flow a compensating current that also compensates for the reactive component of the fundamental wave, thereby improving the power factor of the fundamental wave. To realize these functions in the active filter device (4), the active filter device (4) of this embodiment includes a current source (30), a controller (43), a voltage detector (46), a first current detection unit (5), and a second current detection unit (47), as shown in Figure 1.

[0042] -Voltage detector, current detection unit- The voltage detector (46) is a sensor that detects the voltage (Vrs) of the AC power supply (3).

[0043] Furthermore, the second current detection unit (47) is for detecting the current values ​​(hereinafter referred to as current values ​​(Ir2a, It2a)) input to the active filter device (4). In this example, the second current detection unit (47) includes a current detector (45a) and a current detector (45b). The current detector (45a) detects the R-phase current value (Ir2a) input from the AC power supply (3) to the active filter device (4), and the current detector (45b) detects the T-phase current value (It2a) input from the AC power supply (3) to the active filter device (4). The detected values ​​from each current detector (45a, 45b) are transmitted to the controller (43) (more specifically, the second current calculation unit (434) described later).

[0044] The configuration of each current detector (45a, 45b) is not particularly limited. For example, it is conceivable to employ a current transformer. These current detectors (45a, 45b) may be configured to transmit the detected value to the controller (43) by a wired method or may be configured to transmit the detected value by a wireless method. In FIG. 1, only two phases of the current detectors (45a, 45b) constituting the second current detection unit (47) are shown, but there is no problem in configuring the second current detection unit (47) with three current detectors to detect the current of three phases.

[0045] On the other hand, the first current detection unit (5) is an example of a load information detection unit and detects the current value in the power reception path (12) of the air conditioner (11). Specifically, the first current detection unit (5) detects the current value of the AC power supply (3) at a stage before the current from the AC power supply (3) branches to each load device (harmonic generation load device). In this example, the first current detection unit (5) includes a current detector (4a) and a current detector (4b). These current detectors (4a, 4b) detect the current of the AC power supply (3) at a stage before it is input to the distribution board (60). More specifically, the current detector (4a) detects the current value (Irs) of the R phase in the AC power supply (3), and the current detector (4b) detects the current value (Its) of the T phase in the AC power supply (3). The detected values of the respective current detectors (4a, 4b) are transmitted to the controller (43) (more specifically, the first current calculation unit (435) described later).

[0046] The configuration of each current detector (4a, 4b) is not particularly limited. For example, it is conceivable to employ a current transformer. The current detector (4a) and the current detector (4b) may be configured to transmit the detected value to the controller (43) by a wired method or may be configured to transmit the detected value by a wireless method.

[0047] Further, the first current detection unit (5) may be configured to be installed inside the distribution board (60) or outside it. In this embodiment, the current detectors (4a, 4b) are installed inside the distribution board (60). By installing the current detectors (4a, 4b) inside the distribution board (60), rain and wind will not hit the current detectors (4a, 4b) and the like, so that the reliability of the current detectors (4a, 4b) can be enhanced and the lifespan can be extended. Also, the detected values of the current detectors (4a, 4b) are configured to be transmitted to the controller (43) by a wireless method. The distance between the distribution board (60) and the air conditioner (11) may be 20 to 30 meters apart. Therefore, it takes a great deal of effort to connect the current detectors (4a, 4b) inside the distribution board (60) to the air conditioner (11) by wire. On the other hand, in this embodiment, since the detected values of the current detectors (4a, 4b) are configured to be transmitted to the controller (43) by a wireless method, wired construction work can be reduced.

[0048] Also, the phenomenon in which the magnetic flux passing through the current detectors (4a, 4b) changes with time due to the current flowing through the current detectors (4a, 4b) is called electromagnetic induction, and the induced electromotive force, which is the electromotive force generated by this electromagnetic induction, may be used as a power source (for example, a power source for communication) to drive the first current detection unit (5). By doing so, the first current detection unit (5) can operate in a non-powered mode (that is, operate without connecting a power source from the outside of the first current detection unit (5)). By configuring the first current detection unit (5) to be able to operate in a non-powered mode, there is an effect of reducing the labor of construction work and the like.

[0049] - Current source (30) - The current source (30) generates a current (that is, a compensation current) for reducing harmonic current and improving the fundamental power factor. The output terminal of the current source (30) is connected to the power reception path (12) of the power conversion device (1), and the generated compensation current is output to the power reception path (12). The current source (30) of this embodiment is configured using a so-called inverter circuit. A switching command value (G), which will be described later, is input to the current source (30) from the controller (43). The current source (30) generates a compensation current by switching according to the switching command value (G).

[0050] -Controller (43)- Figure 2 is a block diagram showing an example of a controller (43) according to Embodiment 1. The controller (43) controls the output current of the current source (30). In this example, the controller (43) includes a gate pulse generator (431), a current command calculation unit (432), a load current calculation unit (433), a second current calculation unit (434), a first current calculation unit (435), and a phase detection unit (436). The controller (43) can be configured, for example, using a microcomputer and a memory device that stores a program for operating it.

[0051] The phase detection unit (436) receives the voltage (Vrs) detected by the voltage detector (46) as input, detects the phase of the power supply voltage in the power receiving path (12), and transmits the detected phase to the first current calculation unit (435) and the second current calculation unit (434).

[0052] The first current calculation unit (435) determines the current (referred to as the first current value (i1)) necessary to perform both harmonic current compensation (reduction of harmonic current) and fundamental wave reactive component compensation (power factor improvement of the fundamental wave) based on the phase detected by the phase detection unit (436) and the current values ​​(Irs, Its) detected by the current detectors (4a, 4b), and outputs the first current value (i1) to the load current calculation unit (433). More specifically, it extracts the harmonic current component and the fundamental wave reactive component from the detected values ​​(current values ​​(Irs, Its)) of the current detectors (4a, 4b) and outputs them as the first current value (i1).

[0053] Furthermore, the second current calculation unit (434) determines the current (referred to as the second current value (i2)) flowing into the active filter device (4), which performs both harmonic current compensation (reduction of harmonic current) and fundamental wave reactive component compensation (power factor improvement of the fundamental wave), based on the phase detected by the phase detection unit (436) and the current values ​​(Ir2a, It2a) detected by the current detectors (45a, 45b), and outputs the second current value (i2) to the load current calculation unit (433). More specifically, it extracts the harmonic current component and the fundamental wave reactive component from the detected values ​​(current values ​​(Ir2a, It2a)) of the current detectors (45a, 45b) and outputs them as the second current value (i2).

[0054] The load current calculation unit (433) calculates the currents flowing through the load (2) (a three-phase harmonic generating load) and the power converter (1) (a harmonic generating load). Here, the following relationship holds for each phase between the current values ​​of each phase input to the load (2), which is an example of a three-phase harmonic generating load (Ir1L, Is1L, It1L), the current values ​​of each phase input to the air conditioner (11) (Ir2, Is2, It2), the current values ​​of each phase input to the power converter (1) (i.e., the harmonic generating load) (Ir2L, Is2L, It2L), and the current values ​​of each phase input to the active filter device (4) (Ir2a, Is2a, It2a).

[0055] R phase: Irs = Ir1L + Ir2 = Ir1L + Ir2L + Ir2a S phase: Iss = Is1L + Is2 = Is1L + Is2L + Is2a .... (1) T phase: Its = It1L + It2 = It1L + It2L + It2a As can be seen from these relationships, subtracting the current values ​​of each phase (Ir2a, Is2a, It2a) input to the active filter device (4) from the current values ​​of each phase (Irs, Iss, Its) flowing through the AC power supply (3) results in the following equation.

[0056] R phase: Irs - Ir2a = Ir1L + Ir2 - Ir2a = Ir1L + Ir2L + Ir2a - Ir2a S phase: Iss - Is2a = Is1L + Is2 - Is2a = Is1L + Is2L + Is2a - Is2a ....(2) T phase: Its - It2a = It1L + It2 - It2a = It1L + It2L + It2a - It2a These equations (2) can be rearranged as follows.

[0057] As can be seen from equation (3) above, by subtracting the current values ​​of each phase (Ir2a, Is2a, It2a) input to the active filter device (4) from the current values ​​of each phase (Irs, Iss, Its) flowing through the AC power supply (3), the currents flowing through the load device (2) (three-phase harmonic generating load device) and the power converter (1) (harmonic generating load device) can be determined. By utilizing this, in this embodiment, the fundamental wave power factor and generated harmonics of the load device (2) and the power converter (1) are suppressed, improving the fundamental wave power factor at the distribution and receiving ends near the AC power supply (3) and reducing harmonic currents. Specifically in this embodiment, the load current calculation unit (433) calculates the current flowing through the load device (2) and the power converter (1) and outputs it to the current command calculation unit (432). Specifically, the load current calculation unit (433) calculates the difference between the first current value (i1) and the second current value (i2) and outputs it to the current command calculation unit (432).

[0058] The current command calculation unit (432) calculates a current value with the opposite phase to the current calculated by the load current calculation unit (433) and outputs this value as a current command value (Iref) to the gate pulse generator (431). The gate pulse generator (431) generates a switching command value (G) that instructs switching in the inverter circuit constituting the current source (30). More specifically, the gate pulse generator (431) performs feedback control, repeatedly generating a switching command value (G) based on the deviation between the output current value of the current source (30) and the current command value (Iref). As a result, a current (compensation current) corresponding to the current command value (Iref) is supplied from the current source (30) to the power receiving path (12). More specifically, the gate pulse generator (431) outputs a switching command value (G) to the current source (30) such that the second current value (i2) obtained by the second current calculation unit (434) matches the current command value (Iref). As a result, the harmonic components contained in the current flowing through the load (2) and the power converter (1) cancel each other out with the current output by the active filter (4), and the current flowing from the AC power supply (3) becomes a sine wave with the harmonic currents removed, thus improving the power factor.

[0059] <Operation of the active filter device (4)> Since the active filter device (4) is incorporated into the air conditioning system (100), when power is supplied to the air conditioning system (100), the active filter device (4) also becomes operational.

[0060] When the current command calculation unit (432) generates a current command value (Iref), the gate pulse generator (431) generates a switching command value (G), and the current source (30) outputs a compensation current corresponding to the current command value (Iref) to the power receiving path (12). In this embodiment, it is possible to reduce harmonic currents caused not only by the air conditioner (11) but also by other loads (2) and improve the fundamental wave power factor.

[0061] <Effects of this embodiment> As described above, this embodiment makes it possible to reduce harmonic currents in a power system in which multiple load devices (here, power converter (1) and load device (2)) are connected. Furthermore, this embodiment also makes it possible to improve the fundamental wave power factor.

[0062] <Embodiment 2 of the Invention> Figure 3 is a block diagram showing an air conditioning system (100) according to Embodiment 2 of the present invention. The difference from Embodiment 1 is that the other load device (21), which is a harmonic generating load device, is a device driven by a single-phase voltage, and the other load device (21) is assumed to be a lighting device such as an LED or a single-phase fan / pump. In this embodiment, assuming that the connection phase of the other load device (21), i.e., the device driven by a single-phase voltage, is unknown, the first current detection unit (5) is provided with three current detectors (4a, 4b, 4c) to detect the current value of each phase (R, S, T) of the AC power supply (3) (i.e., the current value of all three phases). In other words, with this configuration, even if the load device (21) is a device that operates on single-phase AC, the current value can be reliably detected.

[0063] With the above configuration, according to this embodiment, when a single-phase load (21) is connected together with the air conditioner (11), it is possible to reduce harmonic currents. Furthermore, in this embodiment, it is also possible to improve the fundamental wave power factor.

[0064] Furthermore, if the phase of the AC power supply (3) to which the single-phase load (21) is connected is known in advance, the first current detection unit (5) may be configured to install current detectors (4a, 4b) only on the two phases to which the load (21) is connected.

[0065] <Embodiment 3 of the Invention> Figure 4 is a block diagram showing an air conditioning system (100) according to Embodiment 3 of the present invention. The difference from Embodiment 1 is that, as shown in Figure 4, multiple loads are connected to the power system. Specifically, a load (22), which is a three-phase harmonic generating load, and a load (21), which is a three-phase harmonic generating load, are connected to this power system. In other words, in this embodiment, in addition to the power converter (1), there are two harmonic generating loads (three-phase). In this way, even if there are multiple harmonic generating loads (three-phase), the same effect can be obtained by performing the same control as in Embodiment 1. That is, according to this embodiment, when multiple other loads (21, 22) are connected together with the air conditioning device (11), it is possible to reduce harmonic currents. Furthermore, in this embodiment, it is also possible to improve the fundamental wave power factor.

[0066] Embodiment 4 of the Invention Figure 5 is a block diagram showing an air conditioning system according to Embodiment 4 of the present invention. The difference from Embodiment 1 is that, as shown in Figure 5, multiple air conditioning units (11, 11) (two in this example) are provided in the power system. In this example, each of these air conditioning units (11, 11) is equipped with an active filter device (4). By having multiple air conditioning units (11), it is possible to reduce the current load capacity of the active filter device (4). Therefore, in this embodiment, the current capacity of the active filter device (4) can be reduced, which lowers costs and allows for a smaller size.

[0067] Figure 6 shows an example of a block diagram of the controller (43) in this embodiment. The difference from Embodiment 1 is that the current values ​​(Irs, Its) of each phase flowing through the AC power supply (3), detected by the current detectors (4a, 4b), are input to the unit count calculation unit (437) of the controller (43). The unit count calculation unit (437) considers the number of active filter devices (4) that are responsible for reducing and improving the harmonic current and power factor of the load device (21), which is a harmonic generating load device. In this embodiment, there are two active filter devices (4) for one load device (21) (i.e., a harmonic generating load device), so assuming that the current capacities of these active filter devices (4) are the same, the unit count calculation unit (437) outputs the values ​​obtained by dividing the current values ​​(Irs) and current values ​​(Its) detected by the current detectors (4a, 4b) by 2 to the first current calculation unit (435). This allows us to determine the phase-specific compensation currents to be shared by a single active filter device (4). In this example, the output power of each active filter device (4) is half of what it would be if a single active filter device (4) were outputting the compensation current.

[0068] Furthermore, if the current capacities of the active filter devices (4) are different, the current to be shared is determined according to the current capacities. For example, if one active filter device (4) has a current capacity of 10 kW and the other active filter device (4) has a current capacity of 50 kW, the unit count calculation unit (437) of the 10 kW active filter device (4) outputs to the first current calculation unit (435) the values ​​obtained by dividing the current values ​​(Irs) and (Its) detected by the current detectors (4a, 4b) by 6. The first current calculation unit (435) outputs a first current value (i1) according to these values ​​sent from the unit count calculation unit (437). The unit count calculation unit (437) of the 50 kW active filter device (4) outputs to the first current calculation unit (435) the value obtained by multiplying the current values ​​(Irs, Its) detected by the current detectors (4a, 4b) by 5 / 6. The first current calculation unit (435) outputs a first current value (i1) according to the value sent from the unit count calculation unit (437). The output power of each active filter device (4) is reduced compared to when a single active filter device (4) outputs a compensation current.

[0069] As described above, according to this embodiment, when multiple air conditioning units (11,11) and other load devices (21) are connected to a power system, it becomes possible to reduce harmonic currents. Furthermore, in this embodiment, it becomes possible to improve the fundamental wave power factor.

[0070] 《Embodiment 5 of the Invention》 Figure 7 is a block diagram showing an air conditioning system (100) according to Embodiment 5 of the present invention. The air conditioning system (100) is an example of a device with a built-in active filter, and incorporates an air conditioning device (11) and an active filter device (4). The air conditioning system (100) is installed in buildings, factories, apartments, detached houses, etc. (hereinafter referred to as "buildings, etc."). Buildings, etc. are supplied with power from a power grid that includes an AC power source (3). In this example, the AC power source (3) is a three-phase AC power source (commercial power).

[0071] Furthermore, buildings are equipped with a distribution board (60) that is connected to an AC power source (3) and receives AC power from the AC power source (3). The distribution board (60) has multiple circuit breakers, and distributes the AC power from the AC power source (3) to multiple devices via each circuit breaker. In this example, an air conditioning system (100) is connected to one of these circuit breakers. The air conditioning system (100) operates using the AC power supplied via the distribution board (60).

[0072] Specifically, the air conditioning unit (11) is equipped with a refrigerant circuit (not shown) that circulates a refrigerant to perform refrigeration cycle operation, and is used to cool or heat rooms in buildings and the like. The refrigerant circuit of the air conditioning unit (11) is equipped with a compressor that compresses the refrigerant. In addition, as shown in Figure 7, the air conditioning unit (11) is equipped with a converter circuit (511), a reactor (512), a capacitor (513), an inverter circuit (514), and a motor (515).

[0073] The converter circuit (511) is a circuit that converts alternating current (AC) to direct current (DC). For example, the converter circuit (511) is composed of a diode bridge circuit. The capacitor (513) smooths the output of the converter circuit (511). The inverter circuit (514) converts the DC, which has been smoothed by the capacitor (513), into AC having a predetermined frequency and voltage. Specifically, the inverter circuit (514) comprises a plurality of (six in this case) switching elements connected in a bridge configuration, and converts the DC to AC by switching the input DC.

[0074] The motor (515) of the air conditioning unit (11) is a so-called IPM motor (Interior Permanent Magnet Motor). The motor (515) drives the compressor. If no measures are taken, the operation of the motor (515) will add harmonic currents to the power system current (hereinafter referred to as system current (Is)).

[0075] In addition, a load device (20) separate from the air conditioning unit (11) is also connected to one of the circuit breakers. Here, an elevator is given as an example of a load device (20). As shown in Figure 7, the elevator is equipped with a converter circuit (521), a reactor (522), a capacitor (523), an inverter circuit (524), and a motor (525). The converter circuit (521) is a circuit that converts alternating current to direct current and has the same configuration as the converter circuit (511) of the air conditioning unit (11). The capacitor (523) smooths the output of the converter circuit (521). The inverter circuit (524) converts the direct current smoothed by the capacitor (523) into alternating current having a predetermined frequency and predetermined voltage. The inverter circuit (524) has the same configuration as the converter circuit (511). The motor (525) is also a so-called IPM motor and drives the elevator. If no measures are taken, the operation of the motor (525) will add harmonic currents to the system current (Is).

[0076] <Configuration of the Active Filter Device> As shown in Figure 7, the active filter device (4) is equipped with a current source (5110), a power factor controller (5120), and a PWM controller (5140). In this example, the active filter device (4) is incorporated into the air conditioning system (100) together with the air conditioning unit (11). The active filter device (4) improves the power factor and suppresses harmonics of the air conditioning unit (11) by supplying a compensation current (Ic), which will be described later, to the power supply system. Here, as an example, the direction from the active filter device (4) to the AC power supply (3) is considered positive for the compensation current (Ic). Furthermore, the sum of the system current (Is) and the compensation current (Ic) is assumed to be equal to the sum of the current flowing from the power supply system (AC power supply (3)) to the air conditioning unit (11) (load current (I1)) and the current flowing from the power supply system (AC power supply (3)) to the load (20) (load current (I2)).

[0077] -Current source (5110)- The current source (5110) comprises an inverter circuit (5111) and a capacitor (5113). The capacitor (5113) is composed of, for example, an electrolytic capacitor. The inverter circuit (5111) causes the capacitor (5113) to charge and discharge by inputting and outputting a compensation current (Ic). In this example, the inverter circuit (5111) is connected to the AC power supply (3) via a three-phase reactor (5160).

[0078] In the inverter circuit (5111) of this embodiment, although detailed illustrations are omitted, six switching elements (5112) are connected in a bridge configuration. This inverter circuit (5111) changes the switching state (on / off state) of each of the multiple switching elements (5112) in synchronization with a carrier signal of a predetermined frequency, thereby inputting and outputting a compensation current (Ic). The on / off control of the switching elements (5112) is performed by a PWM controller (5140). In this example, a low-pass filter (5150) is provided between the reactor (5160) and the connection point between the breaker and the air conditioner (11) to remove ripple from the compensation current (Ic). The low-pass filter (5150) is a so-called LC filter.

[0079] - Power Factor Controller (5120) - The power factor controller (5120) comprises a power supply phase detector (5121), a phase calculation unit (5122), three current sensors (5123, 5124, 5125), three DQ converters (5126, 5127), a high-pass filter (5129), two adders (5130, 5132), three subtractors (5131, 5133, 5135), a voltage controller (5134), and two current controllers (5136, 5137). Specifically, the main part of the power factor controller (5120) can be configured using a microcomputer and a memory device containing software for operating it.

[0080] The power supply phase detector (5121) is connected to predetermined lines (any two of the r-phase, s-phase, and t-phase) of the AC power supply (3), detects the phase of the line voltage, and outputs it to the phase calculation unit (5122). The phase calculation unit (5122) uses the signal output by the power supply phase detector (5121) (called the zero-crossing signal (S1)) to determine the phase (ωt) between the lines to which the power supply phase detector (5121) is connected. The phase calculation unit (5122) outputs the determined phase (ωt) to the dq converter (5126), dq converter (5127), and dq converter (5128).

[0081] The current sensor (5123) is located outside the air conditioning system (100) and detects the load current (I1). The load current (I1) is three-phase, but the current sensor (5123) detects the load current (ir1, it1) of two of the three phases. The current sensor (5124) detects the compensation current (Ic). The compensation current (Ic) is also three-phase, but the current sensor (5124) detects the load current of two of the three phases. In addition, the current sensor (5125) is located outside the air conditioning system (100) and detects the load current (I2). The load current (I2) is also three-phase, but the current sensor (5125) detects the load current (ir2, it2) of two of the three phases. Furthermore, since the load current (I1, I2) and compensation current (Ic) can be easily calculated by detecting the current values ​​of two of the three phases, each current sensor (5123, 5124, 5125) only needs to be configured to detect the current of two phases. In addition, various configurations of current sensors (5123, 5124, 5125) can be used. An example of these current sensors (5123, 5124, 5125) is a current transformer. It is also possible to configure the current sensor (5125) to transmit the detected value to the dq converter (5128) wirelessly.

[0082] The dq converter (5126) performs a three-phase / two-phase conversion (dq-axis conversion) on the load current (I1) (three-phase) obtained from the detection value of the current sensor (5123). Here, the d-axis and q-axis are a rotating coordinate system that rotates in synchronization with the phase (ωt) obtained by the phase calculation unit (5122). The q-axis component (hereinafter, q-axis component (iq1*)) obtained as a result of the conversion by the dq converter (5126) is the reactive current in the air conditioning system (11). On the other hand, the d-axis component obtained as a result of the conversion is the active current in the air conditioning system (11). The dq converter (5126) outputs the q-axis component (iq1*) to the adder (5130) and the d-axis component to the high-pass filter (5129).

[0083] The dq converter (5127) performs a three-phase / two-phase conversion on the compensation current (Ic) obtained from the detection value of the current sensor (5124) to obtain the d-axis component, which is the active current (hereinafter referred to as the d-axis current (id)), and the q-axis component, which is the reactive current (hereinafter referred to as the q-axis current (iq)). The d-axis current (id) is output to the subtractor (5135), and the q-axis current (iq) is output to the subtractor (5131).

[0084] Furthermore, the dq converter (5128) performs a three-phase / two-phase conversion on the load current (I2) (three-phase) obtained from the detection value of the current sensor (5125) to obtain the q-axis component (iq2*). The q-axis component (iq2*) is the reactive current in the load device (20). The q-axis component (iq2*) obtained by the dq converter (5128) is output to the adder (5130). As a result, the adder (5130) outputs the sum of the q-axis component (iq1*) and the q-axis component (iq2*). This sum can be considered as the total value of the reactive current in the building, etc., where the active filter device (4) is installed. In other words, this sum can be considered as the q-axis component of the current that should flow as the compensation current (Ic). Hereafter, this sum will be called the q-axis current command value (iq*).

[0085] The high-pass filter (5129) removes the DC component from the d-axis component of the load current (I1) output by the dq converter (5126) and outputs it to the adder (5132). The output of the dq converter (5126) is DC if there are no harmonic components in the load current (I1). This is because the component of the load current (I1) that is synchronized with the phase of the AC power supply (3) appears as DC. In other words, the high-pass filter (5129) outputs only the harmonic components contained in the d-axis component of the load current (I1) to the adder (5132).

[0086] If the compensation current (Ic) is applied such that the d-axis component and q-axis component of the compensation current (Ic) each match the harmonic components of the load current (I1), then the harmonic components of the load current (I1) can be canceled out (hereinafter, applying current in such a way that predetermined components are canceled out is called compensation). In other words, the output of the high-pass filter (5129) can be used to generate the command value (d-axis current command value (id*)) of the d-axis component (d-axis current (id)) of the compensation current (Ic).

[0087] On the other hand, the q-axis component (iq1*) of the load current (I1) output by the dq converter (5126) also includes a DC component. Therefore, by superimposing a current corresponding to this q-axis component (iq1*) onto the compensation current (Ic), it becomes possible to reduce the harmonic components contained in the load current (I1) and also improve the fundamental wave power factor.

[0088] In this example, the output of the high-pass filter (5129) is not used directly as the d-axis current command value (id*), but is modified to accommodate fluctuations in the terminal voltage of the capacitor (5113) (hereinafter referred to as the DC voltage (Vdc)). Specifically, in the power factor controller (5120), the subtractor (5133) first calculates the deviation between the DC voltage (Vdc) of the capacitor (5113) and its command value (Vdc*). The voltage controller (5134) performs proportional-integral control based on the deviation obtained by the subtractor (5133) to obtain a corrected value. This corrected value is added to the output of the high-pass filter (5129) in the adder (5132), and the summation result is output as the d-axis current command value (id*). This reduces the influence of fluctuations in the DC voltage (Vdc).

[0089] The subtractor (5135) calculates the deviation (Δid) obtained by subtracting the d-axis current (id) from the d-axis current command value (id*), and outputs the deviation (Δid) to the current controller (5136). The subtractor (5131) also calculates the deviation (Δiq) obtained by subtracting the q-axis current (iq) from the q-axis component (iq1*), and outputs the deviation (Δiq) to the current controller (5137).

[0090] The current controller (5136) outputs a d-axis voltage command value (Vid), which is one of the two-phase voltage command values, by utilizing an algorithm such as feedback control (e.g., so-called PID control) based on the deviation (Δid). The current controller (5137) outputs a q-axis voltage command value (Viq), which is one of the two-phase voltage command values, by utilizing an algorithm such as feedback control (e.g., so-called PID control) based on the deviation (Δiq).

[0091] - PWM Controller (5140) - The PWM controller (5140) generates a switching command value (drive signal (G)) to drive the current source (5110) based on the d-axis voltage command value (Vid) and the q-axis voltage command value (Viq). Specifically, the PWM controller (5140) performs so-called PWM (pulse width modulation) control to cause the current source (5110) to input and output a compensation current (Ic). The PWM controller (5140) can be configured using a microcomputer and a memory device that stores the software for operating it.

[0092] <Operation of the Active Filter Device> Since the active filter device (4) is incorporated into the air conditioning system (100), the air conditioning system (100) must be energized in order to operate the active filter device (4). When this is done, the power factor controller (5120) of the active filter device (4) determines the q-axis component (iq1*) of the load current (I1) based on the detected value of the current sensor (5123). In addition, the dq converter (5128) determines the q-axis component (iq2*) based on the detected value of the current sensor (5125).

[0093] The q-axis component (iq1*) of the load current (I1) and the q-axis component (iq2*) of the load current (I2) are added together by an adder (5130) and output as a q-axis current command value (iq*). From this q-axis current command value (iq*), the q-axis current (iq) calculated by the dq converter (5127) is subtracted by a subtractor (5131) and output as a deviation (Δiq).

[0094] Furthermore, in the power factor controller (5120), a d-axis current command value (id*) is generated by the operation of a dq converter (5126), etc. From this d-axis current command value (id*), the d-axis current (id) obtained by the dq converter (5127) is subtracted by a subtractor (5135) and output as a deviation (Δid).

[0095] Once the deviation (Δid) is determined, the current controller (5136) outputs a d-axis voltage command value (Vid). Similarly, once the deviation (Δiq) is determined, the current controller (5137) outputs a q-axis voltage command value (Viq). As a result, a drive signal (G) corresponding to the d-axis voltage command value (Vid) and the q-axis voltage command value (Viq) is output from the PWM controller (5140) to the inverter circuit (5111). Consequently, a compensation current (Ic) with components corresponding to the d-axis current command value (id*) and the q-axis current command value (iq*) flows from the current source (5110). This reduces the harmonic current from the air conditioner (11) in the system current (Is) and improves the fundamental power factor.

[0096] <Effects of this Embodiment> As described above, in this embodiment, with respect to the air conditioning system (11), both harmonic components of its active current and reactive current are compensated, thereby reducing harmonic current and improving the power factor. On the other hand, with respect to other loads (20) connected to the same power system as the air conditioning system (11), power factor improvement (compensation) is performed based only on their reactive current, and no compensation is performed for the active current. In other words, since the active filter device (4) does not compensate for the active current of other loads (20), there is no need to secure the capacity of the active filter device (4) for that purpose. Therefore, by applying this embodiment, when another load (20) is connected to the power system together with the air conditioning system (11), it becomes possible to improve the power factor without increasing the capacity of the active filter device (4). This embodiment is a useful configuration when improving the power factor of an entire building, etc., by utilizing the surplus capacity of the active filter device (4) incorporated in the air conditioning system (11).

[0097] 《Modified Version of Embodiment 5》 Figure 8 is a block diagram showing an air conditioning system (100) according to a modified version of Embodiment 5. As shown in the figure, the air conditioning system (100) according to this modified version has a low-pass filter (5138) added to the active filter device (4) of Embodiment 5. In this example, an inductive motor (525) that does not contain harmonic components in its current is connected as a load device (20) separate from the air conditioning device (11). In this case as well, if no measures are taken, the system current (Is) will be in a lagging phase.

[0098] In this modified example, as shown in Figure 8, the q-axis component of the dq converter (5128) is passed through the low-pass filter (5138) to the q-axis component (iq2 * It is configured to output as ). Therefore, in this modified example, only the fundamental wave component of the reactive current of the load (20) is compensated. In other words, this modified example is a useful configuration when the reactive current of other loads (20) does not contain harmonic components.

[0099] 《Embodiment 6 of the Invention》 Figure 9 is a block diagram showing an air conditioning system (100) according to Embodiment 6 of the present invention. The air conditioning system (100) is an example of a device with a built-in active filter, and incorporates an air conditioning device (11) and an active filter device (4). The air conditioning system (100) is installed in buildings, factories, apartments, etc. Power is supplied to buildings, etc. from a power system including an AC power source (3). In this example, the AC power source (3) is a three-phase AC power source (commercial power). Note that there is impedance in the power grid of the power system (in Figure 9, a coil symbol is added between the AC power source (3) and the distribution board (60) (described later) to indicate this impedance). Due to the presence of the phase adjustment equipment (200), when power enters the distribution board (60) from the AC power source (3), the current tends to be in leading phase, and due to the presence of this impedance, the power received voltage at the distribution board (60) becomes higher than that of the AC power source.

[0100] Furthermore, buildings are equipped with a distribution board (60) that is connected to an AC power source (3) and receives AC power from the AC power source (3). The distribution board (60) has multiple circuit breakers, and distributes the AC power from the AC power source (3) to multiple devices via each circuit breaker. In this example, an air conditioning system (100) is connected to one of these circuit breakers. The air conditioning system (100) operates using the AC power supplied via the distribution board (60).

[0101] Specifically, the air conditioning unit (11) is equipped with a refrigerant circuit (not shown) that circulates a refrigerant to perform refrigeration cycle operation, and is used to cool or heat rooms in buildings and the like. The refrigerant circuit of the air conditioning unit (11) is equipped with a compressor that compresses the refrigerant. In addition, as shown in Figure 9, the air conditioning unit (11) is equipped with a converter circuit (611), a reactor (612), a capacitor (613), an inverter circuit (614), and a motor (615).

[0102] The converter circuit (611) is a circuit that converts alternating current (AC) to direct current (DC). For example, the converter circuit (611) is composed of a diode bridge circuit. The capacitor (613) smooths the output of the converter circuit (611). The inverter circuit (614) converts the DC, which has been smoothed by the capacitor (613), into AC having a predetermined frequency and voltage. Specifically, the inverter circuit (614) comprises a plurality of (six in this case) switching elements connected in a bridge configuration, and converts the DC to AC by switching the input DC.

[0103] The motor (615) of the air conditioning unit (11) is a so-called IPM motor (Interior Permanent Magnet Motor). The motor (615) drives the compressor. If no measures are taken, the operation of the motor (615) will add harmonic currents to the power system current (hereinafter referred to as system current (Is)). In other words, the air conditioning unit (11) is an example of a harmonic generating device. Although not shown in the diagram, other load devices in this building (such as elevators) also receive power via the distribution board (60).

[0104] Furthermore, buildings and other structures are equipped with phase-shifting equipment (200). Figure 10 schematically shows the configuration of the phase-shifting equipment (200). As shown in Figure 10, the phase-shifting equipment (200) has three series units (for three phases) consisting of a series-connected phase-advancing capacitor (201) and a reactor (202). Each series unit is installed on the input side of the distribution board (60), as shown in Figure 10. More specifically, one end of each series unit is connected to a predetermined phase of the AC power supply (3), and the other ends are connected to each other. Hereafter, the current flowing through the phase-shifting equipment (200) will be named the phase-advancing capacitor current (Isc).

[0105] <Configuration of the Active Filter Device> As shown in Figure 9, the active filter device (4) is equipped with a current source (6110), a power factor controller (6120), and a PWM controller (6140). In this example, the active filter device (4) is incorporated into the air conditioning system (100) together with the air conditioning unit (11). The active filter device (4) improves the power factor and suppresses harmonics of the air conditioning unit (11) by supplying a compensation current (Ic), described later, to the power supply system. Here, as an example, the direction from the active filter device (4) to the AC power supply (3) is considered positive for the compensation current (Ic). Furthermore, the sum of the system current (Is) and the compensation current (Ic) is assumed to be equal to the sum of the current flowing from the power supply system (AC power supply (3)) to the air conditioning unit (11) (load current (I1)) and the phase-advancing capacitor current (Isc) flowing to the phase-shifting equipment (200).

[0106] -Current source (6110)- The current source (6110) comprises an inverter circuit (6111) and a capacitor (6113). The capacitor (6113) is composed of, for example, an electrolytic capacitor. The inverter circuit (6111) causes the capacitor (6113) to charge and discharge by inputting and outputting a compensation current (Ic). In this example, the inverter circuit (6111) is connected to the AC power supply (3) via a three-phase reactor (6160).

[0107] In the inverter circuit (6111) of this embodiment, although detailed illustrations are omitted, six switching elements (6112) are connected in a bridge configuration. This inverter circuit (6111) changes the switching state (on / off state) of each of the multiple switching elements (6112) in synchronization with a carrier signal of a predetermined frequency, thereby inputting and outputting a compensation current (Ic). The on / off control of the switching elements (6112) is performed by a PWM controller (6140). In this example, a low-pass filter (6150) is provided between the reactor (6160) and the connection point between the breaker and the air conditioner (11) to remove ripple from the compensation current (Ic). The low-pass filter (6150) is a so-called LC filter.

[0108] - Power Factor Controller (6120) - The power factor controller (6120) comprises a power supply phase detector (6121), a phase calculation unit (6122), three current sensors (6123, 6124, 6125), three DQ converters (6126, 6127, 6128), a high-pass filter (6129), an adder (6132), three subtractors (6131, 6133, 6135), a voltage controller (6134), and two current controllers (6136, 6137). Specifically, the main part of the power factor controller (6120) can be configured using a microcomputer and a memory device containing software for operating it.

[0109] The power supply phase detector (6121) is connected to predetermined lines (any two of the r-phase, s-phase, and t-phase) of the AC power supply (3), detects the phase of the line voltage, and outputs it to the phase calculation unit (6122). The phase calculation unit (6122) uses the signal output by the power supply phase detector (6121) (called the zero-crossing signal (S1)) to determine the phase (ωt) between the lines to which the power supply phase detector (6121) is connected. The phase calculation unit (6122) outputs the determined phase (ωt) to the dq converter (6126), dq converter (6127), and dq converter (6128).

[0110] The current sensor (6123) is located outside the air conditioning system (100) and detects the load current (I1). The load current (I1) is three-phase, but the current sensor (6123) detects the load current (ir1, it1) of two of the three phases. The current sensor (6124) detects the compensation current (Ic). The compensation current (Ic) is also three-phase, but the current sensor (6124) detects the load current of two of the three phases.

[0111] Furthermore, the current sensor (6125) is an example of a load information detection unit and detects the system current (Is). Here, the system current (Is) is the current for the entire building, including the phase regulating equipment (200). In this example, the current sensor (6125) is installed inside the distribution board (60). That is, the current sensor (6125) is installed outside the air conditioning system (100). The current sensor (6125) is on the input side of the distribution board (60) and detects the current value (system current (Is)) closer to the AC power supply (3) than to the phase regulating equipment (200). Although the system current (Is) is also three-phase, the current sensor (6125) detects the system current (ir2, it2) for two of the three phases. The detected value (system current (Is)) from the current sensor (6125) is transmitted wirelessly to the dq converter (6128). Of course, it is also possible to configure the system to transmit the detected value of the current sensor (6125) to the dq converter (6128) via a wired connection.

[0112] Furthermore, since the load current (I1), system current (Is), and compensation current (Ic) can be easily calculated by detecting the current values ​​of two of the three phases, each current sensor (6123, 6124, 6125) only needs to be configured to detect the current of two phases. In addition, various configurations of current sensors (6123, 6124, 6125) can be used for these current sensors (6123, 6124, 6125). An example of these current sensors (6123, 6124, 6125) is a current transformer.

[0113] The dq converter (6126) performs a three-phase / two-phase conversion (dq-axis conversion) on the load current (I1) (three-phase) obtained from the detection value of the current sensor (6123). Here, the d-axis and q-axis are a rotating coordinate system that rotates in synchronization with the phase (ωt) obtained by the phase calculation unit (6122). The d-axis component obtained as a result of the conversion is the active current in the air conditioning unit (11). The dq converter (6126) outputs the d-axis component to the high-pass filter (6129). The q-axis component obtained as a result of the conversion by the dq converter (6126) is the reactive current in the air conditioning unit (11), but in this embodiment, this q-axis component is not used for control.

[0114] The dq converter (6127) performs a three-phase / two-phase conversion on the compensation current (Ic) obtained from the detection value of the current sensor (6124) to obtain the d-axis component, which is the active current (hereinafter referred to as the d-axis current (id)), and the q-axis component, which is the reactive current. The d-axis current (id) is output to the subtractor (6135). In this embodiment, the q-axis current obtained by the dq converter (6127) is not used for control.

[0115] Furthermore, the dq converter (6128) performs a three-phase / two-phase conversion on the system current (Is) (three-phase) obtained from the detection value of the current sensor (6125) to obtain the q-axis component (hereinafter, q-axis current (iq)). The q-axis current (iq) is the reactive current in the received power. In other words, it can be considered as the total value of the reactive current in a building, etc., where the active filter device (4) is installed. That is, this q-axis current (iq) can be considered as the q-axis component of the current that should flow as the compensation current (Ic). The q-axis current (iq) obtained by the dq converter (6128) is output to the subtractor (6131). Note that in this embodiment, the d-axis current obtained by the dq converter (6128) is not used for control.

[0116] The high-pass filter (6129) removes the DC component from the d-axis component of the load current (I1) output by the dq converter (6126) and outputs it to the adder (6132). The output of the dq converter (6126) is DC if there are no harmonic components in the load current (I1). This is because the component of the load current (I1) that is synchronized with the phase of the AC power supply (3) appears as DC. In other words, the high-pass filter (6129) outputs only the harmonic components contained in the d-axis component of the load current (I1) to the adder (6132).

[0117] If the compensation current (Ic) is applied such that its d-axis and q-axis components match the harmonic components of the load current (I1), then the harmonic components of the load current (I1) can be canceled out (hereinafter, applying current in a way that cancels out predetermined components is referred to as compensation). In other words, the output of the high-pass filter (6129) can be used to generate the command value (d-axis current command value (id*)) of the d-axis component (d-axis current (id)) of the compensation current (Ic).

[0118] In this example, the output of the high-pass filter (6129) is not used directly as the d-axis current command value (id*), but rather modified to accommodate fluctuations in the terminal voltage of the capacitor (6113) (hereinafter referred to as DC voltage (Vdc)). Specifically, in the power factor controller (6120), the subtractor (6133) first subtracts the DC voltage (Vdc) of the capacitor (6113) and its command value (Vdc) * The deviation from the calculated value is determined. The voltage controller (6134) performs proportional-integral control based on the deviation obtained by the subtractor (6133) to obtain a correction value. This correction value is added to the output of the high-pass filter (6129) in the adder (6132), and the summation result is output as the d-axis current command value (id*). This reduces the effect of fluctuations in the DC voltage (Vdc).

[0119] The subtractor (6135) calculates the deviation (Δid) by subtracting the d-axis current (id) from the d-axis current command value (id*), and outputs the deviation (Δid) to the current controller (6136). The subtractor (6131) is also input to a fixed value (specifically zero) as the q-axis current command value (iq*). The subtractor (6131) outputs the value obtained by subtracting the q-axis current (iq) from the q-axis current command value (iq*) (hereinafter referred to as the deviation (Δiq)). The deviation (Δid) is input to the current controller (6137).

[0120] The current controller (6136) outputs a d-axis voltage command value (Vid), which is one of the two-phase voltage command values, by utilizing an algorithm such as feedback control (e.g., so-called PID control) based on the deviation (Δid). The current controller (6137) outputs a q-axis voltage command value (Viq), which is one of the two-phase voltage command values, by utilizing an algorithm such as feedback control (e.g., so-called PID control) based on the deviation (Δiq).

[0121] - PWM Controller (6140) - The PWM controller (6140) generates a switching command value (drive signal (G)) to drive the current source (6110) based on the d-axis voltage command value (Vid) and the q-axis voltage command value (Viq). Specifically, the PWM controller (6140) performs so-called PWM (pulse width modulation) control to cause the current source (6110) to input and output a compensation current (Ic). The PWM controller (6140) can be configured using a microcomputer and a memory device that stores the software to operate it.

[0122] <Operation of the Active Filter Device> Since the active filter device (4) is incorporated into the air conditioning system (100), the air conditioning system (100) must be energized in order to operate the active filter device (4). When this is done, the power factor controller (6120) uses the dq converter (6128) to determine the q-axis current (iq) of the system current (Is) based on the value detected by the current sensor (6125). The subtractor (6131) then subtracts the q-axis current command value (iq*) from the q-axis current (iq) to calculate the deviation (Δiq). Furthermore, the power factor controller (6120) generates the d-axis current command value (id*) through the operation of the dq converter (6126), etc. Furthermore, the subtractor (6135) subtracts the d-axis current (id) obtained by the dq converter (6127) from the d-axis current command value (id*) to calculate the deviation (Δid).

[0123] Once the deviation (Δid) is determined, the current controller (6136) outputs the d-axis voltage command value (Vid). Also, once the deviation (Δiq) is determined, the current controller (6137) outputs the q-axis voltage command value (Viq). As a result, a drive signal (G) corresponding to the d-axis voltage command value (Vid) and the q-axis voltage command value (Viq) is output from the PWM controller (6140) to the inverter circuit (6111).

[0124] For example, if the active filter device (4) were not provided, the system current (Is) would lead in phase due to the phase-advancing capacitor current (Isc) when the load on the air conditioner (11) is small. However, in this embodiment, a q-axis voltage command value (Viq) is generated such that the q-axis component (q-axis current (iq)) in the system current (Is) becomes zero (= q-axis current command value (iq*)). Accordingly, a compensation current (Ic) having a component equivalent to the q-axis current (iq) flows from the current source (6110). As a result, in this embodiment, the phase-advancing capacitor current (Isc), which is leading in phase, is compensated, and the fundamental wave power factor of the received power is improved.

[0125] Furthermore, with respect to the air conditioning system (11), the d-axis component of the compensation current (Ic) is adjusted to compensate for the harmonic components of the load current (I1). As a result, the harmonic components of the active current related to the air conditioning system (11) are also compensated. In other words, the active filter device (4) can also reduce the harmonic current of the air conditioning system (11).

[0126] <Effects of this embodiment> As described above, in this embodiment, the reactive current of the entire building, including the phase-shifting equipment (200), is grasped and compensated for. Therefore, in this embodiment, it becomes possible to improve the power factor of a building equipped with phase-shifting equipment.

[0127] Embodiment 7 of the Invention Figure 11 is a block diagram showing the configuration of a power supply power factor control system (7000) according to Embodiment 7. The power supply power factor control system (7000) comprises a phase adjustment equipment (200) and an air conditioning system (100).

[0128] The air conditioning system (100) is installed in buildings and detached houses (hereinafter referred to as "buildings, etc.") and provides indoor air conditioning (cooling and heating). The above-mentioned buildings, etc. are supplied with power from a power grid that includes an AC power source (3). In this example, the AC power source (3) is a three-phase AC power source (for example, a three-phase commercial power source) and supplies power to the air conditioning system (100), which is a harmonic generating load device. The air conditioning system (100) operates using AC power supplied from the AC power source (3).

[0129] The phase-shifting equipment (200) is installed in a building or similar structure to improve the power factor of the entire building.

[0130] <Configuration of the air conditioning system> The air conditioning system (100) comprises an air conditioning device (11) and an active filter device (4). The air conditioning device (11) comprises a refrigerant circuit (not shown) having a compressor and a power converter (1).

[0131] The refrigerant circuit of the air conditioning system (11) consists of a compressor, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger connected by refrigerant piping. The refrigerant circuit is filled with refrigerant, and the room is cooled or heated as the refrigerant circulates within the circuit.

[0132] The power converter (1) is connected to the AC power source (3) via the phase adjustment equipment (200) and has a converter circuit and an inverter circuit. When the power converter (1) is supplied with AC power from the AC power source (3), it converts it into AC power having a desired frequency and voltage, and supplies the converted power to the compressor (more specifically, the motor equipped in the compressor). As a result the compressor operates and the refrigerant circuit functions, and as a result, indoor air conditioning is performed.

[0133] In an air conditioning system (11), harmonic currents may be generated when the power converter (1) or the compressor motor is in operation. These harmonic currents may flow into the AC power supply (3) through the current path that supplies power to the power converter (1). Generally, the level of such harmonic currents flowing into the AC power supply (3) is regulated.

[0134] Therefore, an active filter device (4) is incorporated into the air conditioning system (100). The active filter device (4) reduces the harmonic currents generated in the power converter (1).

[0135] Furthermore, given the need to improve the fundamental wave power factor at the distribution and receiving ends from the perspectives of equipment capacity and energy conservation, the active filter device (4) also has a function to improve the fundamental wave power factor. By improving the fundamental wave power factor using the active filter device (4), the power factor of the power source is improved.

[0136] The configuration of the active filter device (4) will be described below.

[0137] <Configuration of the Active Filter Device> The active filter device (4) is connected in parallel to the AC power supply (3) with the power converter (1), which is the source of harmonic currents, and has the function of canceling out the harmonic currents that flow out from the power converter (1) and appear in the power receiving path from the AC power supply (3). That is, the active filter device (4) flows a compensation current so that the current in the current path of the AC power supply (3) (hereinafter referred to as the power receiving path (12)) approaches a sine wave. More specifically, the active filter device (4) generates a compensation current that is in the opposite phase to the harmonic currents appearing in the power receiving path (12) and supplies it to the power receiving path (12).

[0138] Furthermore, the active filter device (4) also has a power factor correction function that improves the fundamental wave power factor by flowing the compensation current described above. In this example, the active filter device (4) is configured to flow a compensation current that also compensates for the reactive component of the fundamental wave, thereby improving the fundamental wave power factor.

[0139] To achieve the above functions, the active filter device (4) according to this embodiment includes a current source (730), filter-side current detectors (745a, 745b), filter-side voltage detector (746), and an active filter controller (743), as shown in Figure 11.

[0140] It is believed that the harmonic current generated in the power converter (1) is largest when the load on the air conditioner (11) is at its greatest (for example, at maximum cooling output). Therefore, the capacity (magnitude of the current or power that can be generated) of the active filter device (4) is set assuming the harmonic current at the maximum load of the air conditioner (11). This capacity is called the maximum output capacity. However, generally, the air conditioner (11) is used more often at a smaller load (for example, an intermediate load) than at its maximum load. In that case, it is likely that the active filter device (4), with its maximum output capacity set in this way, will have excess capacity for most of its operating period.

[0141] -Current Source- The current source (730) generates a compensation current to reduce harmonic currents and improve the fundamental wave power factor. The output terminal of the current source (730) is connected to the power converter (1), and the generated compensation current is output to the power receiving path (12).

[0142] Although not shown in the diagram, the current source (730) in this embodiment is configured using a so-called inverter circuit (active filter inverter section). The current source (730) receives a switching command value (G), which will be described later, from the active filter controller (743). The current source (730) generates a compensation current by switching according to the switching command value (G).

[0143] -Filter-side current detector- The filter-side current detectors (745a, 745b) detect the current values ​​(Ir2a, It2a) input to the current source (730) of the active filter device (4).

[0144] In this example, two filter-side current detectors (745a, 745b) are provided in one active filter device (4). The filter-side current detector (745a) detects the R-phase current value (Ir2a) input from the AC power supply (3) to the current source (730), and the filter-side current detector (745b) detects the T-phase current value (It2a) input from the AC power supply (3) to the current source (730). The current values ​​(Ir2a, It2a) detected by the filter-side current detectors (745a, 745b) are transmitted to the active filter controller (743).

[0145] There are no particular limitations on the configuration of the filter-side current detectors (745a, 745b), but for example, a current transformer could be used.

[0146] Furthermore, the filter-side current detectors (745a, 745b) may be configured to transmit the detection results to the active filter controller (743) via a wired connection or via a wireless connection.

[0147] In this embodiment, the case where the filter-side current detectors (745a, 745b) detect the output current values ​​(Ir2a, It2a) of two phases of the AC power supply (3) is illustrated. However, the filter-side current detection unit may be configured to detect the output current values ​​of three phases of the AC power supply (3).

[0148] -Filter-side voltage detector- The filter-side voltage detector (746) is connected to the R and S phases of the AC power supply (3), but not to the T phase. The filter-side voltage detector (746) detects only the line voltage (Vrs) of the AC power supply (3) and inputs it to the active filter controller (743).

[0149] In this embodiment, the case in which the filter-side voltage detector (746) is connected to the output of two phases of the AC power supply (3) is illustrated, but the filter-side voltage detector (746) may also be configured to be connected to the output of three phases of the AC power supply (3).

[0150] - Active Filter Controller - The active filter controller (743) is composed of a microcomputer and a memory device that stores a program for operating the microcomputer. As shown in Figure 11, the active filter controller (743) is connected to a current source (730), filter-side current detectors (745a, 745b), filter-side voltage detector (746), and a phase-shifting equipment controller (233) in the phase-shifting equipment (200), which will be described later. The active filter controller (743) controls the output current (i.e., compensation current) of the current source (730), which is the active filter inverter section, based on the detection results of each detector (745a, 745b, 746) and the current values ​​(Irs, Its) of the AC power supply (3) sent via the phase-shifting equipment controller (233).

[0151] <Configuration of the Phase Shifting Equipment> As shown in Figure 11, the phase shifting equipment (200) is connected on the power receiving path (12) between the output of the AC power supply (3) and the inputs of the power converter (1) and the active filter device (4). The phase shifting equipment (200) includes two phase shifting devices (231, 232), a power meter (236), and a phase shifting equipment controller (233). The power meter (236) is an example of a load information detection unit.

[0152] - Phase-shifting devices - The phase-shifting devices (231, 232) are connected in parallel to the AC power supply (3) along with the power converter (1) and the active filter device (4). The phase-shifting devices (231, 232) control the reactive power of the power supplied to the power converter (1). In this example, the phase-shifting device (231) is a device that can absorb 20 kVar of reactive power, and the phase-shifting device (232) is a device that can absorb 50 kVar of reactive power.

[0153] Both phase-shifting devices (231, 232) consist of three phase-shifting capacitors (Ca, Cb, Cc), three phase-shifting reactors (La, Lb, Lc), and two switches (2311, 2321) (corresponding to the switching section). The reason why the phase-shifting devices (231, 232) include not only phase-shifting capacitors (Ca, Cb, Cc) but also phase-shifting reactors (La, Lb, Lc) is that if a phase-shifting capacitor (Ca, Cb, Cc) short-circuits, the magnitude of the current flowing through the phase-shifting devices (231, 232) can be reduced by the phase-shifting reactors (La, Lb, Lc).

[0154] The switches (2311, 2321) turn the phase-shifting equipment (231, 232) on and off based on the switching signal from the phase-shifting equipment controller (233). In other words, each switch (2311, 2321) is used to switch the corresponding phase-shifting equipment (231, 232) and the AC power supply (3) to a connected or disconnected state.

[0155] -Power meter (load information detection unit), etc.- The power meter (236), which is a load information detection unit that detects load information of the AC power supply (3), is connected on the power receiving path (12) between the output of the AC power supply (3) and the inputs of the phase adjustment equipment (231, 232). The power meter (236) has two power supply side current detectors (234a, 234b) and one power supply side voltage detector (235).

[0156] The power supply side current detectors (234a, 234b) detect the output current of the AC power supply (3) on the power receiving path (12) before the current is branched and flows to each phase adjustment device (231, 232) and the air conditioning system (100). In this example, two power supply side current detectors (234a, 234b) are provided. Specifically, the power supply side current detector (234a) detects the R phase current value (Irs) in the AC power supply (3). The power supply side current detector (234b) detects the T phase current value (Its) in the AC power supply (3).

[0157] The power supply voltage detector (235) is connected to the output terminals of each phase of the AC power supply (3) and detects the line voltages (Vrs, Vst, Vtr) of the AC power supply (3), which are the output voltages of the AC power supply (3).

[0158] The power meter (236), which is a load information detection unit that detects load information of such AC power supply (3), can be an existing power meter or smart meter installed in a building such as an office building. This is because it eliminates the need to separately install sensors and detection circuits for measuring current and voltage, separate from the power meter and smart meter.

[0159] The configuration of the power supply side current detectors (234a, 234b) is not particularly limited, but for example, a current transformer can be used.

[0160] Furthermore, the power supply side current detectors (234a, 234b) may be configured to transmit the detection results to the phase adjustment equipment controller (233) via a wired method or via a wireless method. Note that the distance between the AC power supply (3) and the active filter device (4) may be 20 to 30 meters. Therefore, if the power supply side current detectors (234a, 234b) are connected to the active filter device (4) by wiring, the wiring will have to be run over a long distance, and the connection work between the power supply side current detectors (234a, 234b) and the active filter device (4) will be quite time-consuming. In contrast, by configuring the power supply side current detectors (234a, 234b) to transmit the detection results wirelessly, the above wiring itself becomes unnecessary, and the work of running the wiring is avoided. If existing transmitting equipment is nearby, the transmission may be routed through the existing transmitting equipment, such as by making the connection point wireless up to the nearest connection point.

[0161] Furthermore, electromagnetic induction is the phenomenon in which the magnetic flux passing through the power supply-side current detectors (234a, 234b) changes over time due to the current flowing through them. The induced electromotive force generated by this electromagnetic induction may be used as the power source (for example, a power source for communication) to drive the power supply-side current detectors (234a, 234b). This allows the power supply-side current detectors (234a, 234b) to operate without a power source (i.e., without connecting a power source from outside the power supply-side current detectors (234a, 234b)), eliminating the need to connect the power supply-side current detectors (234a, 234b) to an external power source.

[0162] Furthermore, in this embodiment, the power meter (236), which is a load information detection unit for detecting load information of the AC power supply (3), is provided inside the phase regulating equipment (200). However, the power meter (236), which is a load information detection unit for detecting load information of the AC power supply (3), may be provided outside the phase regulating equipment (200). Note that when the power meter (236) is provided inside the phase regulating equipment (200), as in this embodiment, the power meter (236) is not exposed to rain or wind, thus increasing the reliability of the power meter (236) and extending its lifespan.

[0163] Furthermore, the power supply side current detectors (234a, 234b) are not limited to the two phases of the AC power supply (3), but may be provided corresponding to each of the three phases of the AC power supply (3).

[0164] -Phase Shifting Equipment Controller- The phase shifting equipment controller (233) is composed of a microcomputer and a memory device that stores a program for operating the microcomputer. As shown in Figure 11, the phase shifting equipment controller (233) is connected to the power meter (236), the switches (2311, 2321) of the phase shifting equipment (231, 232), and the active filter controller (743) in the active filter device (4). Based on the signal from the power meter (236), the phase shifting equipment controller (233) calculates the reactive power Pβ and the power factor θαβ themselves, or calculates information for determining the reactive power Pβ and the power factor θαβ. The phase shifting equipment controller (233) also controls the switching of the switches (2311, 2321) and outputs the detection results of the power supply side current detectors (234a, 234b) to the active filter controller (743).

[0165] <Switching control operation of each switch by the phase-shifting equipment controller> As shown in Figure 12, the phase-shifting equipment controller (233) has a power supply power factor calculation unit (2331) and a switching control unit (2332).

[0166] -Power Factor Calculation Unit- The power factor calculation unit (2331) receives the line voltage (Vrs, Vst, Vtr) detected by the power supply side voltage detector (235) in the power meter (236) and the detection results (Irs, Its) from the power supply side current detectors (234a, 234b). The power factor calculation unit (2331) applies these input signals to the following equations (7-1) and (7-2) to calculate the voltages Vα, Vβ and iα, iβ of the two rotating axes (αβ axes).

[0167]

[0168]

[0169] Next, the power factor calculation unit (2331) applies the voltages Vα, Vβ and currents iα, iβ of the two rotating axes (αβ axes) obtained by equations (7-1) and (7-2) above to equations (7-3) and (7-4) below to calculate the active power Pα and reactive power Pβ.

[0170]

[0171]

[0172] By applying the above active power Pα and reactive power Pβ to the following equation (7-5), the power factor θαβ of the AC power source (3) can be obtained.

[0173]

[0174] Equation (7-5) above shows that the larger the reactive power Pβ, the lower the power factor θαβ of the power supply, and conversely, the smaller the reactive power Pβ, the higher the power factor θαβ becomes, resulting in an improvement in the power factor. In this embodiment, the reactive power Pβ is used to generate the switching signal for the phase-shifting equipment (231, 232), but the power factor θαβ of the power supply, or both the reactive power Pβ and the power factor θαβ, may also be calculated and used to generate the switching signal for the phase-shifting equipment (231, 232).

[0175] - Switching Control Unit - The reactive power Pβ calculated by the power factor calculation unit (2331) is input to the switching control unit (2332). The switching control unit (2332) controls the switching of the switches (2311, 2321) in each phase-shifting device (231, 232) so that the combination of connection states between the AC power supply (3) and each phase-shifting device (231, 232) changes according to the reactive power Pβ. Specifically, the switching control unit (2332) applies the reactive power Pβ to the switching combination table (2332a) of each phase-shifting device (231, 232) shown in Figure 13 and makes a logical decision to turn each phase-shifting device (231, 232) on or off. The switching control unit (2332) outputs a switching signal corresponding to this logical decision to the switches (2311, 2321) in each phase-shifting device (231, 232).

[0176] Here, the switching combination table (2332a) in Figure 13 is used as a criterion for logical judgment, and in this case, there are four possible combinations of switching between the 20kVar phase regulating device (232) and the 50kVar phase regulating device (231): 0kVar, 20kVar, 50kVar, and 70kVar.

[0177] In Figure 13, the load range indicated by reactive power Pβ (reactive power load range) is defined into four patterns, for example, “0kVar to 3kVar”, “3kVar to 20kVar”, “20kVar to 50kVar”, and “50kVar to 70kVar”, and the connection status of each phase-shifting device (231, 232) to the power receiving path (12) is shown for each pattern. Such Figure 13 is determined in advance, for example, before the power supply power factor control system (7000) is constructed on site. In Figure 13, when the phase-shifting devices (231, 232) are connected to the power receiving path (12), it is indicated as “connected”, and when the phase-shifting devices (231, 232) are not connected to the power receiving path (12), it is indicated as “open”. In other words, the switches (2311, 2321) corresponding to the phase-shifting equipment (231, 232) marked "Open" disconnect the phase-shifting equipment (231, 232) from the power supply path (12), while the switches (2311, 2321) corresponding to the phase-shifting equipment (231, 232) marked "On" connect the phase-shifting equipment (231, 232) from the power supply path (12).

[0178] For example, in Figures 11 and 13, when the reactive power Pβ gradually increases from 0 kVar to 70 kVar, the switching operations by each switch (2311, 2321) are performed in the following order (1) to (4).

[0179] (1) Both phase-shifting devices (231, 232) are disconnected from the power supply path (12).

[0180] (2) While keeping the 50 kVar phase regulating device (231) disconnected from the power receiving path (12), the 20 kVar phase regulating device (232) is connected to the power receiving path (12).

[0181] (3) The 20 kVar phase regulating device (232) is disconnected from the power receiving path (12), and the 50 kVar phase regulating device (231) is connected to the power receiving path (12).

[0182] (4) While maintaining the state in which the 50 kVar phase regulating device (231) is connected to the power receiving path (12), the 20 kVar phase regulating device (232) is reconnected to the power receiving path (12) (total 70 kVar).

[0183] Furthermore, the switching control unit (2332) reduces the amount of power supplied by the phase-shifting equipment (231, 232) (specifically, the phase-shifting capacitors (Ca, Cb, Cc)) when the reactive power Pβ leads beyond a pre-set cutoff point (a threshold value defining the reactive power load range in Figure 13) (i.e., the compensation for reactive power Pβ by the phase-shifting capacitors (Ca, Cb, Cc) is excessive). In this case as well, the switching control unit (2332) selects a combination of phase-shifting equipment (231, 232) that is necessary and sufficient to compensate for the reactive power Pβ of the load, and controls the selected phase-shifting equipment (231, 232) to be supplied and the other phase-shifting equipment (231, 232) to be discharged.

[0184] If reactive power Pβ is controlled solely by such a phase-shifting equipment controller (233), as shown by the thin solid line in Figure 14, the power factor θαβ of the AC power supply (3) will initially lead the phase of the target power factor when the connection state of each phase-shifting device (231, 232) is switched, within the range where the reactive power Pβ is between 0 kVar and 70 kVar. However, it will then gradually approach the target power factor, repeating this pattern each time the connection state of each phase-shifting device (231, 232) is switched.

[0185] <Power Factor Improvement Control by Active Filter Controller> In response, the active filter controller (743) controls the generation of compensation current by the current source (730) of the active filter device (4) so ​​that the leading power factor, which is controlled by the reactive power Pβ in the phase-shifting equipment controller (233) described above, is improved based on the reactive power Pβ of the AC power supply (3). That is, by controlling the generation of compensation current by the current source (730), the power factor θαβ of the AC power supply (3) is further improved and converges instantaneously to the target power factor.

[0186] As shown in Figure 15, such an active filter controller (743) includes a phase detection unit (7436), a first current calculation unit (7435), a second current calculation unit (7434), a load current calculation unit (7433), a current command calculation unit (7432), and a gate pulse generator (7431).

[0187] The phase detection unit (7436) receives the line voltage (Vrs) of the AC power supply (3) detected by the filter-side voltage detector (746). The phase detection unit (7436) uses the input line voltage (Vrs) to detect the phase of the power supply voltage in the power receiving path (12) and outputs the detected phase to the first current calculation unit (7435) and the second current calculation unit (7434).

[0188] The first current calculation unit (7435) receives the phase of the power supply voltage detected by the phase detection unit (7436) and the current values ​​(Irs, Its) of the AC power supply (3) detected by the power supply side current detectors (234a, 234b). Based on these input signals, the first current calculation unit (7435) determines the current value (hereinafter referred to as the first current value (i1)) necessary to perform both harmonic current compensation (reduction of harmonic current) and reactive component compensation of the fundamental wave (improvement of the power factor of the fundamental wave) in the power receiving path (12). The first current calculation unit (7435) outputs the determined first current value (i1) to the load current calculation unit (7433).

[0189] The second current calculation unit (7434) receives the phase of the power supply voltage detected by the phase detection unit (7436) and the current values ​​(Ir2a, It2a) input to the current source (730) detected by the filter-side current detectors (745a, 745b). Based on these input signals, the second current calculation unit (7434) determines the current flowing into the active filter device (4), which is currently performing both harmonic current compensation (reduction of harmonic current) and fundamental wave reactive component compensation (power factor improvement of the fundamental wave) (hereinafter referred to as the second current value (i2)). The second current calculation unit (7434) outputs the determined second current value (i2) to the load current calculation unit (7433).

[0190] By subtracting the current values ​​(Ir2a, It2a) input to the current source (730) of the active filter device (4) from the current values ​​(Irs, Its) of the AC power source (3), the total current flowing through the power converter (1) and each phase-shifting device (231, 232) of the phase-shifting equipment (200), which are sources of harmonics, can be determined. Using this, in this embodiment, the fundamental wave power factor of the power converter (1) and the leading power factor by the phase-shifting equipment (200) are improved, thereby improving the fundamental wave power factor at the distribution and receiving ends near the AC power source (3) and reducing harmonic currents. In other words, the active filter device (4) in this embodiment can be said to function as a load for correcting the leading power factor of the phase-shifting equipment (200).

[0191] Specifically, the load current calculation unit (7433) calculates the total current flowing through each phase-shifting device (231, 232) of the power converter (1) and phase-shifting equipment (200) by subtracting the second current value (i2) of the second current calculation unit (7434) from the first current value (i1) of the first current calculation unit (7435), and outputs the calculated result to the current command calculation unit (7432).

[0192] The current command calculation unit (7432) calculates a current value with the opposite phase to the calculation result of the load current calculation unit (7433) and outputs that value as the current command value (Iref) to the gate pulse generator (7431).

[0193] The gate pulse generator (7431) generates a switching command value (G) to instruct switching in the inverter circuit (active filter inverter section) that constitutes the current source (730). More specifically, the gate pulse generator (7431) performs so-called feedback control, repeatedly generating a switching command value (G) based on the deviation between the current value output by the current source (730) and the above current command value (Iref). As a result, the current source (730) supplies a current (compensation current) corresponding to the current command value (Iref) to the power receiving path (12).

[0194] More specifically, the gate pulse generator (7431) generates a switching command value (G) such that the second current value (i2) obtained by the second current calculation unit (7434) matches the current command value (Iref), and outputs it to the current source (730). As a result, the harmonic components contained in the current flowing through the power converter (1) and the current output by the active filter device (4) cancel each other out, and the output current (Irs, Itr, Its) of the AC power supply (3) becomes a sine wave with the harmonic currents removed, improving the power factor.

[0195] In this embodiment, as described above, the active filter controller (743) receives not only the current values ​​(Ir2a, It2a) input to the current source (730), but also the current values ​​(Irs, Its) of the AC power supply (3). Therefore, the active filter controller (743) can calculate the sum of the currents flowing through each phase-shifting device (231, 232) and the currents flowing through the power converter (1), and can adjust the compensation current of the current source (730) according to the calculation result. Accordingly, through the series of controls by the active filter controller (743) described above, the active filter controller (743) controls the actual power factor θαβ, which is affected not only by the power converter (1) but also by the phase-shifting devices (231, 232), to match the target power factor.

[0196] In particular, the current source (730) of the active filter device (4) has the property of making the power supply power factor θαβ lagging power factor when it is in operation. The active filter controller (743) controls the operation of the current source (730) of the active filter device (4) so ​​that the leading power factor due to the phase shifting equipment (231, 232) is canceled out by the lagging power factor due to the active filter device (4), and the power supply power factor θαβ of the AC power supply (3) converges to the target power factor.

[0197] Figure 14 shows the power factor θαβ of the power supply when the phase regulating equipment (200) is operating based on the control of the phase regulating equipment controller (233) described above, but the active filter device (4) is not operating, represented by a thin solid line and the target power factor represented by a dashed line. Each time the connection state of each phase regulating device (231, 232) is switched by the phase regulating equipment controller (233), the power factor θαβ of the power supply initially becomes a leading power factor relative to the target power factor and then gradually approaches the target power factor. As a result, in Figure 14, the region of the power factor θαβ that the active filter device (4) should compensate for appears as an area enclosed by the thin solid line and the dashed line.

[0198] In Figure 14, the power factor θαβ of the power supply when the active filter device (4) is operating based on the control of the active filter controller (743) described above is shown by a thick solid line. The power factor θαβ shown by the thick solid line in Figure 14 converges to the target power factor instantaneously compared to the thin solid line, except that it becomes a leading power factor for a moment when the phase-shifting equipment (231, 232) is switched over. This is because the leading power factor due to the phase-shifting equipment (200) is largely canceled out by the lagging power factor due to the active filter device (4). In other words, the region of the power factor θαβ that the active filter device (4) should compensate for is compensated by the operation of the active filter device (4) under the control of the active filter controller (743) described above.

[0199] Therefore, the power factor control system (7000) according to this embodiment can improve the leading power factor caused by the phase shifting equipment (200) by operating the active filter device (4).

[0200] In this embodiment, the case where one air conditioning system (100) is connected to the power receiving path (12) is illustrated. If other devices installed in a building such as a building are also connected to this power receiving path (12), the power supply power factor control system (7000) can reduce the leading power factor caused by the phase adjustment equipment (200) and improve the fundamental wave power factor of the entire building.

[0201] <Effects> When the active filter device (4) is operating, in contrast to the phase regulating equipment (231, 232), the actual power factor θαβ of the power supply becomes a lagging power factor compared to the target power factor. Therefore, in this embodiment, the control of the reactive power Pβ of the phase regulating equipment (231, 232) causes the actual power factor θαβ to lead compared to the target power factor, and this is improved by controlling the operation of the active filter device (4). As a result, the phenomenon in which the actual power factor θαβ leads due to the phase regulating equipment (231, 232) is easily improved, and appropriate compensation for the actual power factor θαβ and improvement of the fundamental wave power factor can be achieved. Consequently, the possibility of increased power loss in the AC power supply (3) power system and the occurrence of problems such as unnecessary voltage increases in the system can be suppressed.

[0202] More specifically, the operation of the active filter device (4) is controlled such that the leading power factor from the phase-shifting devices (231, 232) is canceled out by the lagging power factor from the active filter device (4), causing the power factor θαβ of the AC power supply (3) to converge to the target power factor.

[0203] In this embodiment, the actual value of the reactive power Pβ used in controlling the power factor θαβ can be easily obtained by calculation based on the detection results of the power supply side current detectors (234a, 234b) and the power supply side voltage detector (235).

[0204] Buildings such as offices and factories are connected to power meters (236) that measure power from the actual values ​​of current and voltage. The power meter (236) is an example of a load information detection unit that detects load information of an AC power supply (3). In this embodiment, a power meter (236) that already includes power supply-side current detectors (234a, 234b) and power supply-side voltage detectors (235) is used, so there is no need to specially install sensors or detection circuits for detecting current and voltage. Therefore, there is no need for separate work to install sensors and detection circuits, and costs can be reduced by not having to install sensors and detection circuits.

[0205] In this embodiment, the switching control of the switches (2311, 2321) is performed according to the reactive power Pβ of the AC power supply (3), and the combination of connection states between the AC power supply (3) and the phase-shifting devices (231, 232) is changed as appropriate. For example, the fewer the number of phase-shifting devices (231, 232) that control the reactive power Pβ to the AC power supply (3), the less the leading power factor due to the control of the phase-shifting devices (231, 232) is suppressed, the smaller the compensation amount of the active filter device (4) becomes, and the smaller the capacity of the active filter device (4) can be.

[0206] Furthermore, in this embodiment, the air conditioning system (100) (specifically, the power converter (1) in the air conditioning system (100)) is a harmonic generating device, and the active filter device (4) is incorporated into the air conditioning system.

[0207] 《Other Embodiments》 Note that the active filter device (4) does not necessarily need to have a fundamental wave power factor improvement function. That is, the active filter device (4) may be configured to have only a harmonic current reduction function. Alternatively, the active filter device (4) may be configured to have only a fundamental wave power factor improvement function.

[0208] Furthermore, it is also possible to configure a single air conditioning unit (11) with multiple active filter devices (4). In this case, each active filter device (4) should share the compensation current according to the current capacity of each active filter device (4).

[0209] Furthermore, the load information detection unit, which detects load information of the AC power supply (3), may use a device with a load information measurement function instead of the first current detection unit (5) or current sensor (6125) to calculate and transmit the fundamental wave component of the current, power factor, reactive power, etc. An example of such a device is a so-called smart meter, which is installed in buildings and transmits information such as the amount of electricity used to power companies. In such cases, when using a smart meter, it is preferable to operate the active filter based on load information sent at predetermined time intervals, rather than on instantaneous information such as that from a current detector.

[0210] Furthermore, although the controller (43) is mounted in the active filter device (4) in the above embodiment, it can be mounted anywhere inside the active filter-integrated device. For example, although not shown in the figures, it may be mounted in the power converter (1) in a manner that is shared with the controller for controlling the power converter (1).

[0211] This invention is useful as a device with a built-in active filter.

[0212] 1 Power converter (loader) 2 Loader 3 AC power supply 4 Active filter device 4a Current detector 4b Current detector 4c Current detector 5 First current detection unit (load information detection unit) 11 Air conditioning unit 30 Current source 60 Distribution board 100 Equipment with built-in active filter

Claims

DEPCT631. An device with an active filter installed in the presence of an active filter (4) and connected to an AC power source (3) in which the active filter (4) is configured to perform an operation based on a value detected by a load information sensing unit (5) that detects load information on the AC power source (3) outside the device with the active filter installed.

2. An device with an active filter installed under claim 1 in which, based on a value detected by the active filter (4), outputs a current for at least one reduction of the harmonic current in the AC power source (3) or correction of the fundamental wave power factor in the AC power source (3).3.An active filter device under the claim 1 in which the operation of the active filter (4) is controlled by a controller (43) integrated into the active filter device, and the controller (43) obtains the level of the current (Ic) output by the active filter (4) by using the current (iq2*) corresponding to the reactive current in the load (20) connected to the AC power source (3) and the current (ir1,it1) of the current flowing from the AC power source (3) to the active filter (4).

4. An active filter device under the claim 3 in which the active filter (4) takes only the fundamental wave component of the reactive current to the current (iq2*) corresponding to that reactive current. 5.An active filter device under the provision of claim 1 in which a phase modifier unit (200) is connected to the AC power source (3) in parallel with the active filter device in order to control the reactive power of the AC power source (3) and, based at least on one of the reactive power or power factors of the AC power source (3), the active filter (4) operates to correct the conduction power factor caused by the control of the reactive power by the phase modifier unit (200).

6. An active filter device under the provision of claim 1 in which the magnitude of the currents output from the active filter (4) is calculated by taking: the current (iq) corresponding to the reactive current of the phase modifier unit (200) and the load device (10) other than the active filter device and the currents (ir1,it1) of the currents flowing from the part connected to the AC power source (3) to the load device (10).7.

8. An active filtering device of any of the claims 1 through 6 in which the load information sensing unit (5) is configured to detect current values ​​(Irs,Its) and to transmit those detected current values ​​(Irs,Its) wirelessly.

9. An active filtering device of any of the claims 1 through 7 in which the load information sensing unit (5) operates without a power source.

10. An active filtering device of any of the claims 1 through 8 in which the load information sensing unit (5) is provided with current detectors (4a,4b,4c) for detecting each current value (Irs,Iss,Its) of the current detector corresponding to one of the phases (R,S,T) of the AC power source (3).