Power conversion device, air conditioner, elevator, phase adjustment system, and control method for power conversion device

Abstract

A power conversion device according to the present disclosure comprises: a reactor that is connected to a node transformed to a low voltage from a high-voltage power reception end of a power system; a switching element that is connected to the node via the reactor; and a control unit that controls the operation of the switching element. When a plurality of the power conversion devices are provided to a consumer connected to the power reception end, the control units control the switching elements on the basis of a phase adjustment command for adjusting reactive current flowing through the power reception end, control the reactive currents of the plurality of power conversion devices, and adjust the phase difference between the current and the voltage of the power reception end.

Description

Power conversion device, air conditioner, elevator, phase modulation system, and control method for power conversion device

[0001] The present disclosure relates to a power conversion device, an air conditioner, an elevator, a phase modulation system, and a control method for a power conversion device.

[0002] Power companies sometimes provide a power factor discount by discounting the electricity bill according to the power factor for customers receiving power at extra-high voltage or high voltage. The power factor discount is, for example, in Japan, based on a lagging power factor of 0.85, and for each 0.01 improvement in the power factor, the basic electricity bill is discounted by 1%, with a maximum discount of 15% at a power factor of 1. Many customers have a lagging power factor because a plurality of inductive loads are connected, and they improve the power factor by installing a leading power capacitor for power factor improvement. In the power factor discount, even if the power factor exceeds 1 and becomes a leading power factor and deteriorates, the maximum discount is applied. Therefore, many customers do not introduce a power factor adjustment device that can switch on and off the leading power capacitor according to the power factor. Thus, even during light load conditions, if the leading power capacitor continues to be connected, the power factor may advance too much, and the voltage may become unstable due to the deterioration of the power factor.

[0003] Patent Document 1 discloses a power conversion device provided with power factor adjustment means for advancing the phase of the input current of a converter more than the voltage phase on the power supply side as seen from the converter, and advancing the phase of the input current more than the voltage phase on the primary side of a reactor element. Thereby, the power conversion device disclosed in Patent Document 1 can prevent the power factor from advancing excessively, and can stabilize the voltage value of the power system.

[0004] Japanese Patent Application Laid-Open No. 2007-6680

[0005] However, a plurality of power conversion devices are connected to the power system of a customer, and since the rated power and power consumption also differ for each power conversion device, it is difficult to uniquely determine the phase adjustment for making the power factor 1 for all power conversion devices.

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to provide a power conversion device, an air conditioner, an elevator, and a phase modulation system that can appropriately control the power factor at the high-voltage power receiving end of a power system even in a situation where a plurality of power conversion devices are connected to a customer.

[0007] The power converter according to this disclosure comprises a reactor connected to a node that has been transformed from a high-voltage receiving end of a power system to a low-voltage node, a switching element connected to the node via the reactor, and a control unit that controls the operation of the switching element. When multiple power converters are provided at a consumer connected to the receiving end, the control unit controls the switching element based on a phase adjustment command to adjust the reactive current flowing at the receiving end, thereby controlling the reactive current of the multiple power converters and adjusting the phase difference between the voltage and current at the receiving end.

[0008] The air conditioner according to this disclosure is a power conversion device comprising a reactor connected to a node that has been transformed from a high-voltage receiving end of a power system to a low-voltage node, a switching element connected to the node via the reactor, and a control unit that controls the operation of the switching element, wherein when a plurality of power conversion devices are provided at a consumer connected to the receiving end, the control unit controls the switching element based on a phase adjustment command to adjust the reactive current flowing to the receiving end to control the reactive current of the plurality of power conversion devices and adjusts the phase difference between the voltage and current at the receiving end.

[0009] The elevator according to this disclosure is a power conversion device comprising a reactor connected to a node that has been transformed from a high-voltage receiving end of a power system to a low-voltage node, a switching element connected to the node via the reactor, and a control unit that controls the operation of the switching element, wherein when a plurality of power conversion devices are provided at a consumer connected to the receiving end, the control unit controls the switching element based on a phase adjustment command to adjust the reactive current flowing at the receiving end to control the reactive current of the plurality of power conversion devices and adjust the phase difference between the voltage and current at the receiving end.

[0010] The phase adjustment system according to this disclosure is a power converter comprising a reactor connected to a node that has been transformed from a high-voltage receiving end of a power system to a low-voltage node, a switching element connected to the node via the reactor, and a control unit that controls the operation of the switching element, wherein when a plurality of power converters are provided at a consumer connected to the receiving end, the control unit controls the switching element based on a phase adjustment command to adjust the reactive current flowing to the receiving end to control the reactive current of the plurality of power converters and adjust the phase difference between the voltage and current at the receiving end, a power measurement unit that acquires information including the power factor or the phase of the reactive current at the receiving end, and a controller that receives information from the power measurement unit and transmits a phase adjustment command to the control unit using information from at least one power converter and information from the power measurement unit.

[0011] The control method for a power converter according to this disclosure includes the steps of: receiving a phase adjustment command to adjust the reactive current flowing to the receiving end of a plurality of power converters installed at a consumer connected to the high-voltage receiving end of a power system; and the steps of the control unit controlling a switching element to control the reactive current flowing through the plurality of power converters and adjusting the phase difference between the voltage and current at the receiving end.

[0012] According to the power converter, air conditioner, elevator, phase adjustment system, and control method for the power converter described herein, the power factor at the high-voltage receiving end of the power system can be appropriately controlled even when multiple power converters are connected to a node that has been transformed from a high-voltage receiving end of the power system to a low-voltage node.

[0013] This is a schematic diagram showing the configuration of a phase-shifting system according to Embodiment 1 of this disclosure. This is a schematic diagram showing the configuration of a PWM converter, which is a power converter according to Embodiment 1 of this disclosure. This is a schematic diagram showing the signal flow of a power converter according to Embodiment 1 of this disclosure. This is a schematic diagram showing the configuration of an active filter, which is a power converter according to Embodiment 1 of this disclosure. This is a diagram illustrating the control method of a power converter according to Embodiment 1 of this disclosure. This is a schematic diagram showing the configuration of a phase-shifting system according to Embodiment 2 of this disclosure. This is a schematic diagram showing the configuration of a phase-shifting system according to Embodiment 3 of this disclosure. This is a diagram illustrating the control method of a power converter according to Embodiment 3 of this disclosure.

[0014] The following describes the power converter, air conditioner, elevator, phase adjustment system, and control method of the power converter related to this disclosure, with reference to drawings.

[0015] Embodiment 1. Figure 1 is a schematic diagram showing the configuration of a phase-shifting system according to Embodiment 1 of this disclosure. As shown in Figure 1, the phase-shifting system 1000 is connected to a high-voltage receiving terminal 10 and comprises power converters 100A and 100B, a power measurement unit 20, and a controller 50. In Figure 1, an example is shown in which a power converter 100A, which is a PWM converter, and a power converter 100B, which is an active filter, are provided as multiple power converters. Typical consumers such as buildings and factories receive power at high voltage, which is transformed in the transformer unit 30, and the load is connected at low voltage in the node 40. Generally, high voltage refers to high voltage (voltage exceeding 600V and 7kV or less) and extra-high voltage (voltage exceeding 7kV) as defined in the Technical Standards for Electrical Equipment, and low voltage refers to low voltage (voltage of 600V or less) as defined in the Technical Standards for Electrical Equipment. High voltage and low voltage in this disclosure may include these definitions, or they may simply refer to the relative magnitudes of voltages. At least one of the following is connected to the low-voltage node 40: power converters 100A and 100B, a parallel load 200 connected in parallel to them, and customer equipment 300. In some cases, a customer may have multiple transformer units 30 (not shown), and power converters and loads may be connected to each node 40 of the transformer unit. Customer equipment 300 is equipment installed at the customer's premises that consumes electricity.

[0016] The power measurement unit 20 acquires information including the power factor or the phase of the reactive current at the high-voltage receiving end 10. The controller 50 receives the information from the power measurement unit 20 and uses the information from at least one power converter (power converter 100A or 100B) and the information from the power measurement unit 20 to transmit a phase adjustment command to the control unit 150 of the power converter 100A or power converter 100B. At this time, the phase adjustment command is information that determines the reactive current that power converters 100A and 100B will flow so that the power factor at the high-voltage receiving end 10 becomes a desired value (preferably 1, but may be variable depending on the power factor state of surrounding consumers).

[0017] There are two methods for obtaining information including the power factor or reactive current phase at the high-voltage receiving end 10: Route A, in which information such as the power factor is exchanged with a power measurement unit 20, which corresponds to a smart meter owned by the power company; and Route B, in which the consumer directly obtains information such as the power factor from the power measurement unit 20. In this disclosure, since information exchange between the power measurement unit 20 and the controller 50 is necessary, it is desirable to use Route B, but any means can be used as long as the necessary information can be obtained. Note that the power measurement unit 20 does not have to be installed by the power company, but may be installed individually by the consumer.

[0018] Figure 2 is a schematic diagram showing the configuration of a power converter according to Embodiment 1 of the present disclosure. As shown in Figure 2, the power converter 100A according to Embodiment 1 of the present disclosure is a PWM converter comprising a reactor 110, a switching element 120, and a control unit 150. The reactor 110 is connected to a node 40 which is transformed from a high-voltage receiving end of the power system to a low-voltage node. Here, in Figure 2, the area from the high-voltage receiving end 10 to the low-voltage node 40 is represented as a low-voltage AC power source. The switching element 120 is connected to the node 40 via the reactor 110 and is a power semiconductor such as an IGBT or MOSFET.

[0019] The power converter 100A has, for example, a switching element 120 with a capacitor 130 connected to both ends, and a load connected to both ends of the capacitor 130. The control unit 150 controls the operation of the switching element 120 and is, for example, a microcontroller. The control unit 150 is connected to the controller 50 and receives phase adjustment commands and transmits phase adjustment information (described later).

[0020] Figure 3 is a schematic diagram showing the signal flow of a power converter according to Embodiment 1 of the present disclosure. The control unit 150 of the power converter 100A adjusts the phase difference between the voltage and current waveforms at the high-voltage receiving end 10 by controlling the switching element 120 based on a phase adjustment command to adjust the phase of the reactive current flowing at the high-voltage receiving end 10, thereby causing reactive current to flow from the multiple power converters when multiple power converters are provided at a consumer connected to the high-voltage receiving end 10. The phase adjustment command can vary the current phase at the high-voltage receiving end 10 by adjusting the reactive current to bring this phase difference closer, and for example, by reducing this phase difference to approach 0, the power factor can be adjusted to 1. The control unit 150 is composed of, for example, an active / reactive current detection unit 152, a voltage controller 153, a command conversion unit 154, an adder 155, a current controller 156, a switching signal generation unit 157, a phase adjustment information generation unit 158, etc.

[0021] First, the control unit 150 acquires voltage and current information of node 40 from a sensor 151 installed between node 40 and reactor 110, and separates and detects the active current, which is the current component in phase with the voltage, and the reactive current, which is the other reactive component, using an active / reactive current detection unit 152. At this time, the control unit 150 detects the DC voltage, which is the voltage across capacitor 130, generates an active current command using a voltage controller 153 from the deviation of the target DC voltage command, and determines the active voltage command using a current controller 156 from the deviation of this value from the active current detected by the active / reactive current detection unit 152.

[0022] The phase adjustment command received from the controller 50 is converted into a reactive current command by the command conversion unit 154. The controller 50 obtains the active power P and reactive power Q from the power factor information of the power measurement unit 20 and calculates the power factor by P ÷ √(P^2 + Q^2). Since the power factor is 1 when the reactive power Q is 0, the controller 50 sends a phase adjustment command to the power converter 100A so that the reactive power Q becomes 0. At this time, the controller 50 may determine the phase adjustment command using the deviation between the calculated power factor and a power factor of 1, or it may determine the phase adjustment command using the deviation from the reactive power Q0 from the power measurement unit 20.

[0023] When the command conversion unit 154 transmits a phase adjustment command to the power converter 100A that compensates for a reactive power Q of 1 [kVar], for example, it calculates a reactive current command such that the reactive power Q becomes 1 [kVar]. If the phase difference between the current I and the voltage V is taken as a reference to the voltage V and its phase θ based on the voltage information from the sensor 151, then the reactive power Q is given by Q = VI sinφ. In this case, I sinφ is the reactive current component. The reactive current at the high-voltage receiving end 10 is determined by the reactive currents output from the power converters 100A, 100B, the parallel load 200, and the consumer equipment 300. The power converter 100A (100B) according to Embodiment 1 of this disclosure can bring the power factor closer to 1 by operating in order to cancel out the reactive current at the high-voltage receiving end 10.

[0024] Furthermore, the control unit 150 can determine a reactive voltage command using the current controller 156 based on the difference between the calculated reactive current command and the reactive current detected by the active / reactive current detection unit 152. At this time, the control unit 150 generates a three-phase voltage command using the reference phase θ of the voltage, and generates a switching signal using the switching signal generation unit 157 by comparing it with, for example, a triangular wave carrier, thereby driving the switching element 120. As a result, the control unit 150 can adjust the output voltage of the power converter 100A.

[0025] Furthermore, the control unit 150 examines the active and reactive currents, and the phase adjustment information generation unit 158 ​​outputs phase adjustment information to the outside if there is an excess or deficiency in the adjustment of reactive current based on the phase adjustment command, by including at least one of the output voltage information of multiple power converters (e.g., power converter 100A or 100B), malfunction information of the power converters (power converter 100A or 100B), current quantity constraints and energy quantity constraints of the power converters (power converter 100A or 100B). In this case, the outside to which the phase adjustment information is output is the controller 50, a terminal installed at the consumer, etc. Note that if such information can be generated, it is not limited to active current and reactive current information, but other detectable physical quantities may be used. Also, not limited to cases where there is an excess or deficiency, information on the reactive current flowing through the power converters (power converter 100A or 100B) may be output to the outside as phase adjustment information.

[0026] Figure 4 is a schematic diagram showing the configuration of an active filter, which is a power converter according to Embodiment 1 of the present disclosure. The power converter 100B according to Embodiment 1 of the present disclosure is an active filter comprising, for example, a reactor 110, a switching element 120, and a control unit 150. The difference between power converter 100A and power converter 100B is that no load is connected to either end of the capacitor 130. This is because an active filter is a filter composed of active elements, and no load is directly provided. Therefore, when using power converter 100B, a parallel load 200 is connected to either end of the node 40, which is equivalent to a low-voltage power supply.

[0027] The parallel load 200 has a rectifier unit 159 that rectifies the AC voltage of node 40, and is connected to a reactor 110 and a capacitor 130. An inverter device 141 that converts AC to DC and then back to AC is connected to both ends of the capacitor 130. Although an example is shown in which the inverter device 141 is provided on both ends of the capacitor 130, other power equipment may be connected as a load to both ends of the capacitor 130.

[0028] The operation of the control unit 150 of the power converter 100B is the same as that of the control unit 150 of the power converter 100A. In the case of the power converter 100A, a series load 140 was connected, so the voltage and current were obtained by a sensor 151 installed between node 40 and reactor 110. However, when using the power converter 100B, the control unit 150 needs to adjust the power factor of the high-voltage receiving end 10 by referring to the output voltage of the power converter 100B and the voltage and current of the parallel load 200. For this reason, the sensor 151 is installed between the connection point of the parallel load 200 and reactor 110 and node 40, as shown in Figure 4. As a result, the control unit 150 of the power converter 100B can adjust the reactive current flowing through the power converter 100B and the parallel load 200, and by adjusting the phase difference between the voltage and current of the high-voltage receiving end 10, the reactive current of the high-voltage receiving end 10 can be reduced, and the power factor can be brought closer to 1.

[0029] In this way, by having multiple power converters (power converters 100A and 100B) installed at the customer's site each have a control unit 150, the phase difference between the voltage of power converter 100A and the high-voltage receiving end 10, and between power converter 100B and the parallel load 200 and the high-voltage receiving end 10 are adjusted, thereby reducing the reactive power at the high-voltage receiving end 10 and bringing the power factor closer to 1.

[0030] Figure 5 is a schematic diagram showing a control method for a power converter according to Embodiment 1 of the present disclosure. In the control method for a power converter according to Embodiment 1 of the present disclosure, first in step S1, the controller 50 requests power factor information from the power measurement unit 20.

[0031] Next, in step S2, the power measurement unit 20 transmits power factor information to the controller 50 based on a request from the controller 50.

[0032] In step S3, the controller 50 calculates a phase adjustment command for at least one power converter 100A based on the received power factor information. In step S4, the controller 50 transmits the phase adjustment command to power converter 100A or power converter 100B.

[0033] In step S5, the control unit 150 of at least one power converter (power converter 100A or 100B) receives a phase adjustment command and controls the switching element 120 to control the reactive current flowing through the multiple power converters, thereby adjusting the phase difference between the voltage and current at the high-voltage receiving end 10. At this time, the control unit 150 may also adjust the phase difference between the voltage and current at the high-voltage receiving end 10 by taking into account the voltage of other consumer equipment 300 connected to the consumer.

[0034] In step S6, the control unit 150 transmits phase adjustment information to the controller 50, which includes information on the output voltage of the power converter 100A or 100B, information on malfunctions of the power converter 100A or 100B, and at least one of the current limit and power limit.

[0035] In step S7, the controller 50 requests power factor information from the power measurement unit 20. In step S8, the power measurement unit 20 transmits the power factor information to the controller 50 based on the request from the controller 50.

[0036] In step S9, the controller 50 recalculates a phase adjustment command for at least one power converter 100A based on the received power factor information and phase adjustment information. In step S10, the controller 50 transmits the recalculated phase adjustment command to the power converter 100A or power converter 100B. In other words, the control unit 150 corrects the phase adjustment command according to the operating state of the load connected to the power converter. By feeding back and adjusting the phase adjustment command between the power converter 100A or power converter 100B, the controller 50, and the power measurement unit 20 in this way, the power factor of the high-voltage receiving end 10 can be adjusted more precisely.

[0037] Based on the above, the control method for a power converter according to the present disclosure includes the steps of: receiving a phase adjustment command to adjust the phase of the reactive current flowing to the high-voltage receiving end 10 in a control unit 150 of a plurality of power converters installed at a consumer connected to the high-voltage receiving end 10 of a power system; and the steps of the control unit 150 controlling the switching element 120 to control the reactive current flowing through the plurality of power converters and adjusting the phase difference between the voltage and current at the receiving end (high-voltage receiving end 10).

[0038] Furthermore, the power converters 100A and 100B according to this disclosure are power converters comprising a reactor 110 connected to a node 40 that has been transformed from a high-voltage receiving end 10 of the power system to a low voltage, a switching element 120 connected to the node 40 via the reactor 110, and a control unit 150 that controls the operation of the switching element. When a plurality of power converters are provided at a consumer connected to the high-voltage receiving end 10, the control unit 150 controls the switching element 120 based on a phase adjustment command to adjust the reactive current flowing at the receiving end (high-voltage receiving end 10) to control the reactive current of the plurality of power converters and adjust the phase difference between the voltage and current at the receiving end (high-voltage receiving end 10).

[0039] Furthermore, the phase adjustment system 1000 according to this disclosure is a power conversion device comprising a reactor 110 connected to a node 40 that has been transformed from a high-voltage receiving end 10 of a power system to a low voltage, a switching element connected to the node 40 via the reactor, and a control unit that controls the operation of the switching element 120. When a plurality of power conversion devices are provided to a consumer connected to the high-voltage receiving end 10, the control unit 150 controls the switching element 120 based on a phase adjustment command to adjust the reactive current flowing to the receiving end (high-voltage receiving end 10) to control the reactive current of the plurality of power conversion devices and adjust the phase difference between the voltage and current at the receiving end (high-voltage receiving end 10). The power conversion device comprises a power measurement unit 20 that acquires information including the power factor or the phase of the reactive current at the high-voltage receiving end 10, and a controller 50 that receives information from the power measurement unit 20 and transmits a phase adjustment command to the control unit 150 using information from at least one power conversion device and information from the power measurement unit 20.

[0040] According to the power converter 100A (100B), phase adjustment system 1000, and control method for the power converter of this disclosure, the control unit 150 controls switching elements to adjust the phase difference between the output voltages of the multiple power converters and the voltage at the high-voltage receiving end 10. This reduces the reactive current at the high-voltage receiving end 10, bringing the power factor closer to 1. Therefore, even when multiple power converters are connected to the high-voltage receiving end of the power system, the power factor at the high-voltage receiving end of the power system can be appropriately controlled.

[0041] Furthermore, in consumers with conventional phase-shifting equipment such as power factor correction capacitors, the power factor correction capacitors cannot finely adjust the power factor, and leading power factor, especially at light loads, has been a problem. However, by using the technology of the power converters 100A and 100B and the phase-shifting system 1000 of this disclosure, it becomes possible to control the power factor to near 1, thereby solving the aforementioned problem. In addition, the power converters 100A and 100B and the phase-shifting system 1000 of this disclosure do not require phase-shifting equipment such as power factor correction capacitors, so not only is cost savings reduced, but installation space is also reduced, making effective use of the space inside the consumer's premises possible.

[0042] Further, in the power conversion device 100A (100B) and the phase modulation system 1000 according to Embodiment 1 of the present disclosure, when there is an excess or deficiency in the adjustment of the reactive current based on the phase modulation command by the phase modulation information including at least any one of the information on the output voltage of a plurality of power conversion devices, the information on the malfunction of the power conversion device, the current amount constraint of the power conversion device, and the power amount constraint, the control unit 150 outputs the phase modulation information to the outside. As a result, the user or the controller 50 can grasp information such as the operation status of the power conversion device 100A (100B) of the customer. Therefore, the power conversion device 100A (100B) and the phase modulation system 1000 according to Embodiment 1 of the present disclosure can improve the accuracy of the power factor adjustment at the high-voltage power receiving end 10.

[0043] Further, in the power conversion device 100A (100B) and the phase modulation system according to Embodiment 1 of the present disclosure, the control unit 150 corrects the phase modulation command according to the operation state of the load connected to the power conversion device. Therefore, the power conversion device 100A (100B) and the phase modulation system 1000 according to Embodiment 1 of the present disclosure can improve the accuracy of the power factor adjustment at the high-voltage power receiving end 10.

[0044] Embodiment 2. In Embodiment 2, the same reference numerals are used for the same components as those in Embodiment 1 of the present disclosure, and the description of the same or corresponding parts is omitted. Hereinafter, the phase modulation system 1001 according to Embodiment 2 will be described with reference to the drawings. In Embodiment 2, an example in which the power conversion devices 100A and 100B are provided in the customer's load is shown.

[0045] Figure 6 is a schematic diagram showing the configuration of a phase adjustment system according to Embodiment 2 of the present disclosure. The phase adjustment system 1001 according to Embodiment 2 of the present disclosure has an air conditioner 500 equipped with a power converter 100A or an air conditioner 500 connected in parallel with a power converter 100B. In the air conditioner 500, the power consumption changes according to the air conditioning load, such as indoor temperature, outdoor temperature, and the number of people in the room. The power converters 100A and 100B can arbitrarily change the power factor of the air conditioner 500 according to the load of the air conditioner and generally operate to bring the power factor closer to 1. In this disclosure, in order to control the power factor of the high-voltage receiving end 10 to 1, the power converters 100A and 100B control the reactive power to be supplied by making the power factor of the air conditioner 500 variable, and the power factor of the power measurement unit 20, which the power company uses to determine power factor discounts on electricity charges, can be set to 1.

[0046] If the reactive power of the power measurement unit 20 is A, the reactive power of the air conditioner is B, the reactive power of other loads is C, and the reactive power of the power converters 100A and 100B is D, then the control units 150 provided in the power converters 100A and 100B need to control the reactive power of the air conditioner 500 so that A - (B + C + D) = 0.

[0047] The power measurement unit 20 typically measures reactive power at intervals of 1 to 30 minutes. Therefore, if the air conditioning load changes during the measurement interval, the reactive power B of the air conditioner 500 may change. For example, while the reactive current command based on the operation command in Figure 3 is updated every 1 to 30 minutes, the active and reactive currents calculated by the active / reactive current detection unit 152 by measuring the voltage and current information of node 40 are updated more frequently than the operation command. As a result, if the power converters 100A and 100B operate based on the operation command from the controller 50, there is a possibility that the output will deviate from the reactive power that should be output. Therefore, if the reactive power D of the power converters 100A and 100B is not changed according to the operating state of the air conditioner 500, there is a risk that the electricity rate discount may not be enjoyed due to excessive leading power factor causing a voltage rise in the power system or a lagging power factor.

[0048] In a consumer's home, in order to prevent voltage increases in the power system due to excessive leading power factors and lagging power factors, a dedicated sensor can be provided to measure the reactive power of the load connected to the high-voltage power receiving end 10 and node 40 in real time. However, this will increase the equipment cost. Therefore, since the air conditioner 500 accounts for the majority of the power consumption of general consumers, and the power conversion devices 100A and 100B can measure the reactive power according to the load state of the air conditioner 500, the control unit 150 adjusts the reactive power that the power conversion devices 100A and 100B should output. For this reason, the phase modulation system 1001 according to Embodiment 2 of the present disclosure can avoid excessive leading power factors and lagging power factors by adjusting the reactive power of the power conversion devices 100A and 100B in联动 with the reactive power of the air conditioner with a large power consumption ratio. Generally, since the air conditioner 500 is also often centrally managed by the controller 50, the load information of the air conditioner 500 and the phase modulation information of the power conversion devices 100A and 100B can be aggregated in the controller 50, and according to the change in the load of the air conditioner 500, the power conversion devices 100A and 100B can be configured to send operation instructions.

[0049] In addition, the power conversion devices 100A and 100B may be provided in the elevator 400 as consumer equipment. When provided in the elevator 400, the power factor of the high-voltage power receiving end 10 becomes a lagging power factor due to a rotating machine (not shown) provided in the hoisting machine. The elevator 400 can reduce the reactive current of the high-voltage power receiving end 10 by providing the power conversion devices 100A and 100B of the present disclosure and make the power factor approach 1. Even in a situation where a plurality of power conversion devices (power conversion devices 100A and 100B) are connected to the high-voltage power receiving end 10 of the power system, the power factor of the high-voltage power receiving end 10 of the power system can be appropriately controlled.

[0050] Furthermore, the power conversion devices 100A and 100B may also be provided in other devices such as a blower, lighting, a crane or a conveyor in a factory, etc. As long as it can output reactive power, the same operation can be realized using any device.

[0051] Embodiment 3. In Embodiment 3, the same reference numerals are used for the same components as in Embodiment 1 of this disclosure, and descriptions of the same or corresponding parts are omitted. Hereinafter, the phase adjustment system 1002 according to Embodiment 3 will be described with reference to the drawings. Embodiment 3 shows an example of a phase adjustment system in which a power factor adjustment device that controls power equipment and power converters 100A and 100B work together.

[0052] Figure 7 is a schematic diagram showing the configuration of a phase adjustment system according to Embodiment 3 of the present disclosure. The phase adjustment system according to Embodiment 3 of the present disclosure comprises a power converter and 100B, a power factor adjustment device 25 that switches the number of operating power devices according to the power factor of the high-voltage receiving end 10, and a controller 50. The power devices controlled by the power factor adjustment device 25 are equipment capable of adjusting the phase of the system, such as conventional phase-advancing capacitors (not shown). The power factor adjustment device 25 has a function to adjust the number of phase-advancing capacitors to switch on and off according to the current power factor. Therefore, the power factor adjustment device 25 transmits a signal to the controller 50 related to the number of phase-advancing capacitors to switch on and off.

[0053] Each power factor correction capacitor has a predetermined amount of reactive power (in units of Var) that it can adjust. Therefore, the amount of reactive power that each power factor correction capacitor should adjust is stored in the controller 50 in advance, and the amount of reactive power to be adjusted is calculated according to the number of operating power factor correction capacitors transmitted from the power factor adjustment device 25, and an operation instruction is given to the power converters 100A and 100B on how much reactive power they should output. As a result, the power converters 100A and 100B can operate in the same way as conventional power factor correction capacitors.

[0054] Figure 8 is a schematic diagram showing a control method for a power converter according to Embodiment 3 of the present disclosure. In the control method for a power converter according to Embodiment 3 of the present disclosure, first, in step S1, the power factor adjustment device 25 transmits a phase adjustment command to the controller 50 according to the power factor state of the high-voltage receiving end 10.

[0055] In step S2, the controller 50 calculates a phase adjustment command for at least one power converter 100A (100B) based on the received phase adjustment command. In step S3, the controller 50 transmits the phase adjustment command to the power converter 100A (100B).

[0056] In step S4, the control unit 150 controls the switching elements of at least one power converter 100A (100B) based on a phase adjustment command to adjust the phase difference between the output voltage of the power converter 100A (100B) and the voltage of the high-voltage receiving terminal 10. In step S5, the control unit 150 transmits phase adjustment information to the controller 50, which includes at least one of the output voltage information of the power converter 100A or 100B, information on malfunctions of the power converter 100A or 100B, current constraints, and power constraints.

[0057] In step S6, the power factor adjustment device 25 transmits a phase adjustment command to the controller 50 according to the power factor of the high-voltage receiving end 10. In step S7, the controller 50 recalculates the phase adjustment command for at least one power converter 100A (100B) based on the received phase adjustment command and phase adjustment information. In step S8, the controller 50 transmits the recalculated phase adjustment command to the power converter 100A or power converter 100B. In other words, the control unit 150 corrects the phase adjustment command according to the operating state of the load connected to the power converter. By feeding back and adjusting the phase adjustment command between the power converter 100A or power converter 100B, the controller 50, and the power factor adjustment device 25 in this way, the power factor of the high-voltage receiving end 10 can be adjusted more precisely.

[0058] Based on the above, the phase adjustment system 1002 according to Embodiment 3 of the present disclosure comprises a power converter 100A (100B), a power factor adjustment device 25 that switches the number of operating power equipment according to the power factor of the high-voltage receiving end 10, and a controller 50 that transmits a phase adjustment command to the power converter 100A (100B) and causes the power converter 100A (100B) to output reactive power according to the number of operating power equipment using information from at least one power converter 100A (100B) and information from the power factor adjustment device 25.

[0059] By operating in this manner, the phase-shifting system 1002 according to Embodiment 3 of this disclosure makes it possible to make the power converter 100A and power converter 100B operate in the same manner as conventional power factor correction capacitors. Therefore, the phase-shifting system 1002 according to Embodiment 3 of this disclosure makes it possible to reduce electricity charges by improving the power factor of the high-voltage receiving end 10 and to eliminate voltage increases caused by leading power factors in the power grid. Furthermore, since power factor correction capacitors are components with a limited lifespan, it is possible to configure the system so that only the power factor adjustment device 25 remains when it is time to replace them, and the controller 50 gives operating instructions to the power converter 100A and power converter 100B. Therefore, by including the power factor adjustment device 25, the phase-shifting system 1002 according to Embodiment 3 of this disclosure can also reduce costs by replacing power factor correction capacitors.

[0060] The configurations shown in the embodiments described above are merely examples of the content of this disclosure and can be combined with other known technologies. Furthermore, it is possible to omit or modify parts of the configuration without departing from the gist of this disclosure.

[0061] 10 High-voltage receiving terminal, 20 Power measurement unit, 25 Power factor adjustment device, 30 Transformer unit, 40 Node, 50 Controller, 100A 100B Power converter, 110 Reactor, 120 Switching element, 130 Capacitor, 140 Series load, 141 Inverter device, 150 Control unit, 151 Sensor, 152 Active / Reactive current detection unit, 153 Voltage controller, 154 Command conversion unit, 155 Adder, 156 Current controller, 157 Switching signal generation unit, 158 Phase adjustment information generation unit, 159 Rectifier unit, 200 Parallel load, 300 Consumer equipment, 400 Elevator, 500 Air conditioner, 1000 1001 1002 Phase adjustment system

Claims

1. A power conversion device comprising: a reactor connected to a node that has been transformed from a high-voltage receiving end of a power system to a low-voltage node; a switching element connected to the node via the reactor; and a control unit that controls the operation of the switching element, wherein when a plurality of the power conversion devices are provided at a consumer connected to the receiving end, the control unit controls the switching element based on a phase adjustment command to adjust the reactive current flowing to the receiving end, thereby controlling the reactive current of the plurality of power conversion devices and adjusting the phase difference between the voltage and current at the receiving end.

2. The power converter according to claim 1, wherein the control unit outputs the phase adjustment information to the outside when there is an excess or deficiency in the adjustment of the reactive current based on the phase adjustment command, based on phase adjustment information which includes at least one of the reactive current information of the plurality of power converters, information on malfunctions of the power converters, a current limit and an energy limit of the power converters.

3. The power conversion device according to claim 1 or 2, further comprising a capacitor connected to both ends of the switching element and a load connected to both ends of the capacitor.

4. The power converter according to any one of claims 1 to 3, wherein the control unit corrects the phase adjustment command according to the operating state of the load connected to the power converter.

5. An air conditioner equipped with a power conversion device according to any one of claims 1 to 4.

6. An elevator equipped with a power conversion device according to any one of claims 1 to 4.

7. A phase adjustment system comprising: a power converter according to any one of claims 1 to 4; a power measuring unit that acquires information including the power factor of the receiving end or the reactive current; and a controller that receives information from the power measuring unit and transmits a phase adjustment command to the control unit using information from at least one of the power converters and the information from the power measuring unit.

8. A phase adjustment system comprising: a power converter according to any one of claims 1 to 4; a power factor adjustment device that switches the number of operating power equipment according to the power factor of the receiving end; and a controller that transmits the phase adjustment command to the power converter and causes the power converter to output reactive power according to the number of operating power equipment using information from at least one of the power converters and information from the power factor adjustment device.

9. A control method for a power converter, comprising the steps of: receiving a phase adjustment command for a control unit of a plurality of power converters installed at a consumer connected to a high-voltage receiving end of a power system to adjust the reactive current flowing to the receiving end; and the control unit controlling a switching element to control the reactive current flowing through the plurality of power converters and adjusting the phase difference of the waveform with respect to the voltage at the receiving end.

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