Variable-frequency power supply

Abstract

The present invention relates to a variable-frequency power supply for the induction and partial discharge tests of a power transformer, comprising: a first to a third sub-variable-frequency power supply (A, B, C), and a first to a third output terminal (OUT1, OUT2, OUT3); a first terminal (A1) of the first sub-variable-frequency power supply is configured to be capable of being connected to the first output terminal, and a second terminal (A2) is configured to be capable of being connected to the second or third output terminal; a third terminal (B1) of the second sub-variable-frequency power supply is configured to be capable of being connected to the first or second output terminal, and a fourth terminal (B2) is configured to be capable of being connected to the third output terminal; a fifth terminal (C1) of the third sub-variable-frequency power supply is configured to be capable of being connected to the first or third output terminal, and a sixth terminal (C2) is configured to be capable of being connected to the first or third output terminal. Through the technical solution of the present invention, a variable-frequency power supply for the induction and partial discharge tests of a power transformer with flexible combination can be realized.

Description

Technical Field

[0001] The present invention relates to the field of power equipment, and more particularly to a variable-frequency power supply for induction and partial discharge tests of, for example, power transformers. Background Art

[0002] In order to determine the reliability of power transformers and ensure their safe operation, in accordance with national or industrial standards, induction and partial discharge tests must be carried out on power transformers before leaving the factory. In particular, for large power transformers, the voltage level is high and the single-unit capacity is large. Correspondingly, the requirements for the power supply providing power during the test are higher, and a large capacity is required.

[0003] In the prior art, a generator set is usually used to supply power for the induction and partial discharge tests of power transformers. However, the generator set requires a lot of hardware supporting facilities. For example, the installation of the generator set requires a large concrete foundation, cooling water, a cooling oil system, etc. Moreover, the start-up and stop times of the generator set are long, and energy will inevitably be consumed during the standby process. In addition, the maintenance cycle of the generator is long and the maintenance cost is high. Additionally, the generator set itself may experience self-excitation phenomena during the test process.

[0004] Since the variable-frequency power supply performs an AC→DC→AC conversion on the alternating current in the commercial power, it can output a voltage waveform with stable frequency, stable voltage, and an internal resistance close to zero, approaching an ideal AC power supply. Moreover, the variable-frequency power supply has the advantages of simple installation, convenient operation, easy maintenance, high precision, etc., so it has gradually replaced the generator set and is used in the induction and partial discharge tests of power transformers. However, in the prior art, the variable-frequency power supply can only test a single phase of the power transformer, and cannot perform induction and partial discharge tests on three phases of the power transformer simultaneously according to the standard (at this time, a generator set is still required). In addition, the single-unit capacity of the variable-frequency power supply must also be planned according to the maximum capacity of the test product, so a relatively high single-unit cost needs to be invested.

[0005] Therefore, it is necessary to improve the existing variable-frequency power supply for induction and partial discharge tests of power transformers. Summary of the Invention

[0006] In view of this, the present invention provides a variable-frequency power supply for induction and partial discharge tests of power transformers, which can achieve flexible combinations to meet the single-phase or three-phase and different-capacity power consumption requirements in the induction and partial discharge tests of power transformers.

[0007] To this end, according to one aspect of the present invention, there is provided a variable-frequency power supply for induction and partial discharge tests of a power transformer, wherein the variable-frequency power supply includes: a first sub-variable-frequency power supply including a first terminal and a second terminal; a second sub-variable-frequency power supply including a third terminal and a fourth terminal; a third sub-variable-frequency power supply including a fifth terminal and a sixth terminal; a first output terminal; a second output terminal; and a third output terminal; wherein the first sub-variable-frequency power supply, the second sub-variable-frequency power supply, and the third sub-variable-frequency power supply are respectively configured to output single-phase alternating current by subjecting the mains power obtained from the public power grid to AC→DC→AC conversion; wherein the first output terminal, the second output terminal, and the third output terminal are respectively configured to be connected to the terminals of the windings of the power transformer; wherein the first terminal is configured to be connectable to the first output terminal, the second terminal is configured to be connectable to the second output terminal or the third output terminal, the third terminal is configured to be connectable to the first output terminal or the second output terminal, the fourth terminal is configured to be connectable to the third output terminal, the fifth terminal is configured to be connectable to the first output terminal or the third output terminal, and the sixth terminal is configured to be connectable to the first output terminal or the third output terminal.

[0008] According to an embodiment of the present invention, the variable-frequency power supply further includes: a first switch configured to connect the first terminal to the first output terminal, the third terminal to the second output terminal, and the fifth terminal to the third output terminal when the first switch is closed; and a second switch configured to connect the second terminal to the second output terminal, the fourth terminal to the third output terminal, and the sixth terminal to the first output terminal when the second switch is closed.

[0009] According to an embodiment of the present invention, the variable-frequency power supply further includes: a third switch configured to connect the second terminal to the third output terminal, the fourth terminal to the third output terminal, and the sixth terminal to the third output terminal when the third switch is closed; and a fourth switch configured to connect the first terminal to the first output terminal, the third terminal to the first output terminal, and the fifth terminal to the first output terminal when the fourth switch is closed.

[0010] According to an embodiment of the present invention, the variable-frequency power supply further includes: a fifth switch configured to connect the first terminal to the first output terminal and the second terminal to the third output terminal when the fifth switch is closed.

[0011] According to an embodiment of the present invention, the variable frequency power supply further includes: a fourth sub-variable frequency power supply configured to output single-phase alternating current by subjecting the commercial power obtained from the public power grid to AC→DC→AC conversion, and including a seventh terminal and an eighth terminal, wherein the seventh terminal is configured to be communicable with the first output terminal, and the eighth terminal is configured to be communicable with the third output terminal; and a sixth switch configured to, when the sixth switch is closed, connect the seventh terminal to the first output terminal and the eighth terminal to the third output terminal.

[0012] According to an embodiment of the present invention, when the first switch and the second switch are closed, the first sub-variable frequency power supply, the second sub-variable frequency power supply, and the third sub-variable frequency power supply together output three-phase alternating current, wherein the phase angles of the electric powers output by the first sub-variable frequency power supply, the second sub-variable frequency power supply, and the third sub-variable frequency power supply differ from each other by 120 degrees in sequence.

[0013] According to an embodiment of the present invention, when the third switch and the fourth switch are closed and the first switch and the second switch are open, the first sub-variable frequency power supply, the second sub-variable frequency power supply, and the third sub-variable frequency power supply together output single-phase alternating current, wherein the phase angles of the electric powers output by the first sub-variable frequency power supply, the second sub-variable frequency power supply, and the third sub-variable frequency power supply are the same.

[0014] According to an embodiment of the present invention, when the third switch, the fourth switch, and the fifth switch are closed and the first switch and the second switch are open, the first sub-variable frequency power supply, the second sub-variable frequency power supply, the third sub-variable frequency power supply, and the fourth sub-variable frequency power supply together output single-phase alternating current, and the phase angles of the electric powers output by the first sub-variable frequency power supply, the second sub-variable frequency power supply, the third sub-variable frequency power supply, and the fourth sub-variable frequency power supply are the same.

[0015] According to an embodiment of the present invention, when the fifth switch and the sixth switch are closed and the first switch, the second switch, the third switch, and the fourth switch are open, the first sub-variable frequency power supply and the fourth power supply together output single-phase alternating current, and the phase angles of the electric powers output by the first sub-variable frequency power supply and the fourth sub-variable frequency power supply are the same.

[0016] According to an embodiment of the present invention, the first sub-variable frequency power supply, the second sub-variable frequency power supply, the third sub-variable frequency power supply, and the fourth sub-variable frequency power supply respectively include start / stop switches.

[0017] According to an embodiment of the present invention, the variable frequency power supply further includes an input device, a control unit, and an actuating device. Among them, the input device is configured to receive the power consumption demand input by the user and send the power consumption demand to the control unit; the control unit is configured to receive the power consumption demand and generate a combined switch instruction for controlling the opening or closing of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch, as well as configuration parameters of the first sub-variable frequency power supply, the second sub-variable frequency power supply, the third sub-variable frequency power supply, and the fourth sub-variable frequency power supply, and send the combined switch instruction to the actuating device and send the configuration parameters to the first sub-variable frequency power supply, the second sub-variable frequency power supply, the third sub-variable frequency power supply, and the fourth sub-variable frequency power supply; the actuating device is configured to receive the combined switch instruction and cause the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch to open or close through a first switch actuator, a second switch actuator, a third switch actuator, a fourth switch actuator, a fifth switch actuator, and a sixth switch actuator corresponding to the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch respectively, so as to connect the terminals of multiple sub-variable frequency power supplies among the first sub-variable frequency power supply, the second sub-variable frequency power supply, the third sub-variable frequency power supply, and the fourth sub-variable frequency power supply to the first output terminal, the second output terminal, and the third output terminal, and the connected multiple sub-variable frequency power supplies set their own operating parameters according to the configuration parameters and start running, thereby combining into the variable frequency power supply.

[0018] According to an embodiment of the present invention, the variable frequency power supply further includes a fault diagnosis device configured to monitor the operating parameters of the first sub-variable frequency power supply, the second sub-variable frequency power supply, the third sub-variable frequency power supply, and the fourth sub-variable frequency power supply, and compare the monitored operating parameters with a threshold value preset in the fault diagnosis device. When the difference between the monitored operating parameters of the first sub-variable frequency power supply and the threshold value exceeds a predetermined range, the fault diagnosis device generates a fault signal and sends the fault signal to the control unit. The control unit generates a replacement switch instruction for controlling the opening or closing of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch according to the received fault signal, and sends the replacement switch instruction to the actuating device. The actuating device adjusts the opening or closing of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch respectively through the first switch actuator, the second switch actuator, the third switch actuator, the fourth switch actuator, the fifth switch actuator, and the sixth switch actuator, so that the first terminal and the second terminal of the first sub-variable frequency power supply are respectively disconnected from the first output terminal and the third output terminal, and the seventh terminal and the eighth terminal of the fourth sub-variable frequency power supply are respectively connected to the first output terminal and the third output terminal.

[0019] According to an embodiment of the present invention, each of the first sub-variable frequency power supply, the second sub-variable frequency power supply, the third sub-variable frequency power supply, and the fourth sub-variable frequency power supply includes a control module, and the control module communicates with the control unit of the variable frequency power supply. Wherein, the control module includes a receiving device, a parameter setting device, and a sending device. After the control unit generates the configuration parameters, it sends them to the receiving device, and then the receiving device transfers the configuration parameters to the parameter setting device, and the parameter setting device sets the operating parameters according to the configuration parameters.

[0020] As can be seen from the above solution, since the present invention provides a variable frequency power supply that can be flexibly combined according to the power consumption needs, it can meet the power consumption requirements of the induction and partial discharge tests of power transformers, and can use equipment more reasonably and save energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following will make the above and other features and advantages of the present invention clearer to those of ordinary skill in the art by describing the preferred embodiments of the present invention in detail with reference to the accompanying drawings, in which:

[0022] Figure 1 FIG. is a schematic block diagram showing the main components of a variable frequency power supply for induction and partial discharge tests of a power transformer according to an embodiment of the present invention;Figure 2 To show Figure 1 a schematic diagram of the first exemplary circuit connection of the variable-frequency power supply shown;

[0023] Figure 3 To show Figure 1 a schematic diagram of the second exemplary circuit connection of the variable-frequency power supply shown.

[0024] Among them, the reference numerals are as follows:

[0025] A first sub-variable-frequency power supply B second sub-variable-frequency power supply C third sub-variable-frequency power supply

[0026] D fourth sub-variable-frequency power supply A1 first terminal A2 second terminal

[0027] B1 third terminal B2 fourth terminal C1 fifth terminal

[0028] C2 sixth terminal D1 seventh terminal D2 eighth terminal

[0029] OUT1 first output terminal OUT2 second output terminal OUT3 third output terminal

[0030] K1 first switch K2 second switch K3 third switch

[0031] K4 fourth switch K5 fifth switch K6 sixth switch

[0032] FC variable-frequency power supply Specific embodiments

[0033] To make the objectives, technical solutions and advantages of the present invention clearer, the following examples are listed to further elaborate on the present invention in detail. Those skilled in the art should understand that these exemplary embodiments do not impose any limitations on the present invention. In addition, the features in the embodiments of the present invention can be combined with each other without conflict. In different drawings, the same or similar components are denoted by the same reference numerals, and for the sake of brevity, other components are omitted, but this does not mean that the variable-frequency power supply for the induction and partial discharge tests of power transformers of the present invention cannot include other components. It should be understood that the dimensions, proportional relationships of the components in the drawings, and the number of components do not impose any limitations on the present invention.

[0034] In this article, the terms "first", "second", etc. are used to describe each component, but these components are not limited by these terms. These terms are only used to distinguish one component from other components. Therefore, the first component mentioned below may be the second component in the technical solution of the present invention.

[0035] The following refers to Figure 1 、 Figure 2 and Figure 3Describe the main components of a variable-frequency power supply for induction and partial discharge tests of a power transformer according to an embodiment of the present invention and its exemplary circuit connections. In particular, the following specifically describes with reference to a variable-frequency power supply for induction and partial discharge tests of a power transformer. However, it should be understood that the present invention is not limited to induction and partial discharge tests of a power transformer and can also be used for tests such as fault diagnosis of a power transformer.

[0036] As Figure 1 Schematically shown, a variable-frequency power supply FC for induction and partial discharge tests of a power transformer according to an embodiment of the present invention includes a first sub-variable-frequency power supply A, a second sub-variable-frequency power supply B, and a third sub-variable-frequency power supply C, where each sub-variable-frequency power supply includes its respective terminals. For example, the first sub-variable-frequency power supply A includes a first terminal A1 and a second terminal A2; the second sub-variable-frequency power supply B includes a third terminal B1 and a fourth terminal B2; the third sub-variable-frequency power supply C includes a fifth terminal C1 and a sixth terminal C2. The first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C are configured to output power through their respective terminals. The first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C are respectively configured to convert the mains power obtained from the public power grid through AC→DC→AC conversion and output single-phase alternating current.

[0037] In addition, as Figure 2 shown, a variable-frequency power supply FC for induction and partial discharge tests of a power transformer according to an embodiment of the present invention further includes a first output terminal OUT1, a second output terminal OUT2, and a third output terminal OUT3. Among them, the first output terminal OUT1, the second output terminal OUT2, and the third output terminal OUT3 are respectively configured to be connected to the terminals of the winding (for example, a three-phase winding or a single-phase winding) of the power transformer. As Figure 2 shown, the first terminal A1 is configured to be able to be connected to the first output terminal OUT1, the second terminal A2 is configured to be able to be connected to the second output terminal OUT2 or the third output terminal OUT3, the third terminal B1 is configured to be able to be connected to the first output terminal OUT1 or the second output terminal OUT2, the fourth terminal B2 is configured to be able to be connected to the third output terminal OUT3, the fifth terminal C1 is configured to be able to be connected to the first output terminal OUT1 or the third output terminal OUT3, and the sixth terminal C2 is configured to be connected to the first output terminal OUT1 or the third output terminal OUT3.

[0038] Through the configuration described above, the variable-frequency power supply for the induction and partial discharge tests of a power transformer according to an embodiment of the present invention can provide a flexible combination for different power consumption requirements during the tests. For example, when used for the induction and partial discharge tests of a power transformer, the variable-frequency power supply can replace the generator set to supply power for the three-phase tests of the power transformer, thereby eliminating the disadvantages brought by the generator set, such as the need for large-scale infrastructure, cooling systems, long manufacturing and maintenance cycles, high costs, and self-excitation phenomena. In addition, the variable-frequency power supply for the induction and partial discharge tests of a power transformer according to the present invention has lower requirements for the installation site and supporting facilities. Moreover, since multiple sub-variable-frequency power supplies are used, they can be combined according to the needs of different test object tests, making more reasonable use of the equipment and saving energy.

[0039] The composition of the variable-frequency power supply FC for the induction and partial discharge tests of a power transformer according to an embodiment of the present invention will be further described in detail below in conjunction with specific exemplary power consumption requirements. However, the present invention is not limited to the embodiments given below.

[0040] Continue to refer to Figure 2 , the variable-frequency power supply FC may further include: a first switch K1 and a second switch K2. Wherein, the first switch K1 is configured such that when the first switch K1 is closed, the first terminal A1 is connected to the first output terminal OUT1, the third terminal B1 is connected to the second output terminal OUT2, and the fifth terminal C1 is connected to the third output terminal OUT3; the second switch K2 is configured such that when the second switch K2 is closed, the second terminal A2 is connected to the second output terminal OUT2, the fourth terminal B2 is connected to the third output terminal OUT3, and the sixth terminal C2 is connected to the first output terminal OUT1. By providing the first switch K1 and the second switch K2, quick and convenient operation of the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C can be achieved.

[0041] For example, when the first switch K1 and the second switch K2 are closed, the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C together output three-phase alternating current through the first output terminal OUT1, the second output terminal OUT2, and the third output terminal OUT3, thereby replacing the generator set to supply power for the three-phase induction and partial discharge tests of the power transformer. In this case, the phase angles of the power output by the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C can differ by 120 degrees in sequence to provide three-phase alternating current.

[0042] To provide more combinations and different capacities, the variable-frequency power supply for power transformer tests according to an embodiment of the present invention may further include a third switch K3 and a fourth switch K4. Among them, the third switch K3 is configured such that when the third switch K3 is closed, the second terminal A2 is connected to the third output terminal OUT3, the fourth terminal B2 is connected to the third output terminal OUT3, and the sixth terminal C2 is connected to the third output terminal OUT3; the fourth switch K4 is configured such that when the fourth switch K4 is closed, the first terminal A1 is connected to the first output terminal OUT1, the third terminal B1 is connected to the first output terminal OUT1, and the fifth terminal C1 is connected to the first output terminal OUT1, as Figure 3 shown.

[0043] For example, when the third switch K3 and the fourth switch K4 are closed and the first switch K1 and the second switch K2 are open, the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C together output single-phase alternating current through the first output terminal OUT1 and the third output terminal OUT3, where the phase angles of the power output by the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C are the same. That is to say, these three sub-variable-frequency power supplies provide single-phase three-machine parallel output, correspondingly increasing the capacity for single-phase tests of power transformers. Compared with the prior art, it is not necessary to plan the single-machine capacity of the variable-frequency power supply for induction and partial discharge tests of power transformers as the maximum capacity of the test product. Instead, a combination of sub-variable-frequency power supplies with smaller single-machine capacities is used to test larger-capacity products, so that the equipment can be used more reasonably and energy can be saved.

[0044] The variable-frequency power supply for induction and partial discharge tests of power transformers according to an embodiment of the present invention may further include a fifth switch K5. The fifth switch K5 is configured such that when the fifth switch K5 is closed, the first terminal A1 is connected to the first output terminal OUT1 and the second terminal A2 is connected to the third output terminal OUT3, as Figure 3 shown. In this way, the single-machine power of a single sub-variable-frequency power supply can be output externally.

[0045] For example, when the fifth switch K5 is closed and the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 are open, the first sub-variable-frequency power supply A outputs single-phase alternating current through the first output terminal OUT1 and the third output terminal OUT3. Therefore, the single-phase power consumption requirements with small capacities can be met.

[0046] For the above-described configuration combination, when a fault occurs in one of the first to third sub-inverter power supplies, the entire combination cannot meet the three-phase power supply requirement, and the test work can only be stopped. Therefore, in view of the above situation, the inverter power supply for the induction and partial discharge tests of a power transformer according to another embodiment of the present invention may further include a fourth sub-inverter power supply (D) and a sixth switch K6. The fourth sub-inverter power supply D is configured to output single-phase alternating current by subjecting the mains power obtained from the public power grid to AC→DC→AC conversion, and includes a seventh terminal D1 and an eighth terminal D2. The fourth sub-inverter power supply D is configured to output power through the seventh terminal D1 and the eighth terminal D2. The seventh terminal D1 is configured to be able to communicate with the first output terminal OUT1, and the eighth terminal D2 is configured to be able to communicate with the third output terminal OUT3. The sixth switch K6 is configured such that when the sixth switch K6 is closed, the seventh terminal D1 communicates with the first output terminal OUT1 and the eighth terminal D2 communicates with the third output terminal OUT3. By providing the fourth sub-inverter power supply D, when any one of the three previously mentioned sub-inverter power supplies fails, the fourth sub-inverter power supply D can replace the failed sub-inverter power supply, thus not affecting the progress of the test work. Additionally, since an additional sub-inverter power supply is added, a larger capacity can be provided.

[0047] For example, when the third switch K3, the fourth switch K4, and the fifth switch K5 are closed and the first switch K1 and the second switch K2 are open, the first sub-inverter power supply A, the second sub-inverter power supply B, the third sub-inverter power supply C, and the fourth sub-inverter power supply D together output single-phase alternating current through the first output terminal OUT1 and the third output terminal OUT3, wherein the phase angles of the power output by the first sub-inverter power supply A, the second sub-inverter power supply B, the third sub-inverter power supply C, and the fourth sub-inverter power supply D are the same. That is to say, these four sub-inverter power supplies provide single-phase four-machine parallel output, correspondingly further increasing the capacity for the single-phase induction and partial discharge tests of a power transformer.

[0048] In addition, when the fifth switch K5 and the sixth switch K6 are closed and the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 are open, the first sub-inverter power supply A and the fourth sub-inverter power supply D together output single-phase alternating current through the first output terminal OUT1 and the third output terminal OUT3, wherein the phase angles of the power output by the first sub-inverter power supply A and the fourth sub-inverter power supply D are the same. That is to say, these two sub-inverter power supplies provide single-phase two-machine parallel output, which can provide different capacities for the single-phase induction and partial discharge tests of a power transformer.

[0049] It should be noted that the operations of the switches described above are only examples and are not intended to limit the present invention. Obviously, there can be other combinations of switch operations to provide different combinations between the power supplies. For example, single-phase alternating current can be output by any one, two, or three of the first sub-frequency power supply A, the second sub-frequency power supply B, the third sub-frequency power supply C, and the fourth sub-frequency power supply D, or three-phase alternating current can be output by any three of them. Details are not described herein. Additionally, Figure 2 the switch shown in Figure 2 is a linkage switch capable of simultaneously controlling the connection of two or more terminals, but the present invention is not limited thereto, and a single-action switch that separately controls the connection of each terminal can also be used.

[0050] In addition, the first sub-frequency power supply A, the second sub-frequency power supply B, the third sub-frequency power supply C, and the fourth sub-frequency power supply D respectively include start / stop switches. When the start / stop switches are turned off, the respective sub-frequency power supplies stop operating, thereby saving energy and reducing risks.

[0051] As Figure 1 shown, the capacities of the first sub-frequency power supply A, the second sub-frequency power supply B, the third sub-frequency power supply C, and the fourth sub-frequency power supply D can be the same. For example, they are all 6.3 kV to facilitate the balance of the respective sub-frequency power supplies and improve the utilization efficiency. However, the present invention is not limited thereto. According to different power consumption requirements, the capacities of the first sub-frequency power supply A, the second sub-frequency power supply B, the third sub-frequency power supply C, and the fourth sub-frequency power supply D can also be different from each other, or divided into two groups with different capacities, etc. Moreover, the frequency conversion power supply FC of the present invention is not limited to including four sub-frequency power supplies, but can include more sub-frequency power supplies.

[0052] According to an embodiment of the present invention, the variable-frequency power supply FC for induction and partial discharge tests of a power transformer may further include an input device, a control unit, and an actuating device (not shown). The input device may be a keyboard, a touch screen, etc., which is configured to receive the user's input power demand, for example, the power parameters to be output (including but not limited to the number of output phases, output voltage, output frequency, phase angle between each output phase of the variable-frequency power supply FC), and send the above power demand to the control unit. The control unit is configured to receive the power demand and generate a combined switch command for controlling the opening or closing of the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, and the sixth switch K6, as well as the configuration parameters of the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, the third sub-variable-frequency power supply C, and the fourth sub-variable-frequency power supply D, where the configuration parameters are determined based on the power parameters to be output input by the user. Then, the control unit sends the combined switch command to the actuating device and sends the configuration parameters to the corresponding first sub-variable-frequency power supply A, second sub-variable-frequency power supply B, third sub-variable-frequency power supply C, and fourth sub-variable-frequency power supply D. The actuating device is configured to receive the combined switch command issued by the control unit and cause the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, and the sixth switch K6 to open or close through the first switch actuator, the second switch actuator, the third switch actuator, the fourth switch actuator, the fifth switch actuator, and the sixth switch actuator (not shown) corresponding to the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, and the sixth switch K6 respectively, and cause the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, the third sub-variable-frequency power supply C, and the fourth sub-variable-frequency power supply D to start or stop through the first sub-variable-frequency power supply switch actuator, the second sub-variable-frequency power supply switch actuator, the third sub-variable-frequency power supply switch actuator, and the fourth sub-variable-frequency power supply switch actuator (not shown) corresponding to the start / stop switches of the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, the third sub-variable-frequency power supply C, and the fourth sub-variable-frequency power supply D respectively, so as to connect the terminals of multiple sub-variable-frequency power supplies in the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, the third sub-variable-frequency power supply C, and the fourth sub-variable-frequency power supply D to the first output terminal OUT1, the second output terminal OUT2, and the third output terminal OUT3. At the same time, the multiple connected sub-variable-frequency power supplies set their own operating parameters according to the received configuration parameters and start to operate, thus combining into the variable-frequency power supply FC.

[0053] For example, a user inputs an electricity demand through an input device: output three-phase alternating current, output voltage of 6.3 kV, output frequency of 50 Hz, and phase angle of 120 degrees between each output phase. After receiving the electricity demand, the control unit generates a combined switch command to control the first switch K1 and the second switch K2 to close and the third switch K3 to the sixth switch K6 to open, and sends the combined switch command to the actuating device. Moreover, the control unit generates configuration parameters for the first sub-frequency conversion power supply A, the second sub-frequency conversion power supply B, and the third sub-frequency conversion power supply C, and sends the configuration parameters to the first sub-frequency conversion power supply A, the second sub-frequency conversion power supply B, and the third sub-frequency conversion power supply C respectively. For example, the configuration parameters include: the first sub-frequency conversion power supply A, the second sub-frequency conversion power supply B, and the third sub-frequency conversion power supply C respectively output single-phase alternating current, output voltage of 6.3 kV, output frequency of 50 Hz, and the phase angles between the first sub-frequency conversion power supply A, the second sub-frequency conversion power supply B, and the third sub-frequency conversion power supply C differ by 120 degrees in sequence. Correspondingly, the first sub-frequency conversion power supply A, the second sub-frequency conversion power supply B, and the third sub-frequency conversion power supply C are respectively provided with a receiving device and a parameter setting device. The receiving device is configured to receive the configuration parameters sent by the control unit and transmit the configuration parameters to the parameter setting device. The parameter setting device sets its own operating parameters according to the configuration parameters. The receiving device and the parameter setting device are conventional configurations of the frequency conversion power supply and will not be elaborated here. After receiving the combined switch command from the control unit, the actuating device causes the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, and the sixth switch K6 to open or close according to the combined switch command in a mechanical or electromagnetic manner through the first switch actuator, the second switch actuator, the third switch actuator, the fourth switch actuator, the fifth switch actuator, and the sixth switch actuator as described above, thereby enabling the combination between the first sub-frequency conversion power supply A, the second sub-frequency conversion power supply B, and the third sub-frequency conversion power supply C and supplying power to the power transformer in the three-phase induction and partial discharge tests. The fourth sub-frequency conversion power supply D may include the same configuration as any one of the first sub-frequency conversion power supply A, the second sub-frequency conversion power supply D, and the third sub-frequency conversion power supply C, operate in the same manner, and may replace any one of the first sub-frequency conversion power supply A, the second sub-frequency conversion power supply D, and the third sub-frequency conversion power supply C. Therefore, the configuration and operation of the fourth sub-frequency conversion power supply D will not be further described in detail.

[0054] In addition, the variable-frequency power supply for the induction and partial discharge tests of the power transformer according to the present invention further includes a fault diagnosis device, which is configured to monitor the operating parameters of the first sub-variable-frequency power supply A to the fourth sub-variable-frequency power supply D, and compare the monitored operating parameters with the thresholds preset in the fault diagnosis device. When the difference between the operating parameters of any one of the first sub-variable-frequency power supply A to the fourth sub-variable-frequency power supply D (for example, the first sub-variable-frequency power supply A) and the thresholds preset in the fault diagnosis device exceeds a predetermined range (for example, but not limited to, the proportion of the difference to the threshold is greater than ±5%, ±10%, ±15%), the fault diagnosis device generates a fault signal and sends the fault signal to the control unit. Accordingly, the control unit can generate a replacement switch command for controlling the opening or closing of the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, and the sixth switch K6 according to the received fault signal, and adjust the opening or closing of the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, and the sixth switch K6 through the first switch actuator, the second switch actuator, the third switch actuator, the fourth switch actuator, the fifth switch actuator, and the sixth switch actuator of the actuator device as described above. Accordingly, the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, the third sub-variable-frequency power supply C, and the fourth sub-variable-frequency power supply D are provided with sensors for monitoring their own operating parameters, such as voltage sensors, phase angle sensors, etc., and a sending device, which is configured to send the operating parameters monitored by the sensors to the fault diagnosis device, so that the fault diagnosis device can detect the operating parameters of each sub-variable-frequency power supply. As described above, when the fault diagnosis device receives the operating parameters (for example, voltage) of any one of the first sub-variable-frequency power supply A to the fourth sub-variable-frequency power supply D, it compares them with the thresholds preset in the fault diagnosis device (for example, the voltage in the power consumption demand). If the difference between the operating parameters and the thresholds exceeds a predetermined range, it is determined that this sub-variable-frequency power supply has a fault. At this time, the fault diagnosis device generates a fault signal and transmits the fault signal to the control unit. The control unit can generate and send a replacement switch command to the actuator device according to the received fault signal. After receiving the replacement switch command, the actuator device disconnects the switch corresponding to the faulty sub-variable-frequency power supply through the corresponding switch actuator among the first switch actuator to the sixth switch actuator, thereby removing it from the variable-frequency power supply FC, and then closes the switch corresponding to the standby sub-variable-frequency power supply through another switch actuator among the first switch actuator to the sixth switch actuator, thereby connecting it to the variable-frequency power supply FC.For example, when the fault diagnosis device determines that the first sub - frequency power supply A has a fault, the control unit generates and issues a replacement switch instruction to control the fifth switch K5 to open and the sixth switch K6 to close. Then, according to the received replacement switch instruction, the actuator device disconnects the fifth switch K5 corresponding to the first sub - frequency power supply A through the fifth switch actuator, and at the same time closes the sixth switch K6 corresponding to the fourth sub - frequency power supply D through the sixth switch actuator, so as to realize the replacement of the first sub - frequency power supply A with the fourth sub - frequency power supply D. It should be noted that the operating parameters sensed by the sensors of each of the first sub - frequency power supply A to the fourth sub - frequency power supply D (which can also be referred to as the operating parameters monitored by the fault diagnosis device) are not limited to voltage, and can also be phase angle, frequency, etc. Moreover, various combinations of the opening and closing of the first switch K1 to the sixth switch K6 can be modified in various ways according to the actual power consumption requirements and control strategies, and the number or configuration of switches can be increased or decreased. This application is not limited to the specific manner illustrated above.

[0055] To improve the independent operability of the sub - frequency power supply, each of the first sub - frequency power supply A, the second sub - frequency power supply B, the third sub - frequency power supply C, and the fourth sub - frequency power supply D may include a control module (not shown), and the control module can communicate with the control unit of the frequency - conversion power supply FC to coordinate the operation of the first sub - frequency power supply A, the second sub - frequency power supply B, the third sub - frequency power supply C, and the fourth sub - frequency power supply D. For example, the control module may include the above - mentioned receiving device, parameter - setting device, sending device, etc. For instance, when the control unit generates the configuration parameters of the first sub - frequency power supply A, it sends them to the receiving device of the first sub - frequency power supply A, and then the receiving device transmits the configuration parameters to the parameter - setting device. The parameter - setting device sets the operating parameters of the first sub - frequency power supply A according to the configuration parameters. During the operation of the first sub - frequency power supply A, the sensor detects the operating parameters and sends the sensed operating parameters to the fault diagnosis device for the diagnosis process as described above. It should be noted that the first sub - frequency power supply A in the above example can also be the second sub - frequency power supply B, the third sub - frequency power supply C, or the fourth sub - frequency power supply D.

[0056] It should be noted that the above - described control unit and control module can be implemented either in the form of hardware or in the form of a combination of hardware and software.

[0057] The following briefly describes the operation process of the frequency - conversion power supply for the induction and partial - discharge test of the power transformer of the present invention by way of example.

[0058] First, the user can input the power consumption requirements on the input device of the variable-frequency power supply FC (for example, the output phase number of the variable-frequency power supply FC is three-phase, the phase angle between each output phase is 120 degrees, the output voltage is 6.3 kV, and the output frequency is 50 Hz). Then, the input device sends the above-input power consumption requirements to the control unit. The control unit receives the power consumption requirements and generates a combined switch command for controlling the opening or closing of the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, and the sixth switch K6, and generates the configuration parameters of the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C to be connected. Then, the control unit sends the combined switch command to the actuating device and sends the configuration parameters to the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C. Thereafter, the actuating device receives the combined switch command issued by the control unit and mechanically or electromagnetically causes the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, and the sixth switch K6 to open or close through the first switch actuator, the second switch actuator, the third switch actuator, the fourth switch actuator, the fifth switch actuator, and the sixth switch actuator corresponding to the first switch K1, the second switch K2, the third switch K3, the fourth switch K4, the fifth switch K5, and the sixth switch K6 respectively. And the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C receive the configuration parameters through the receiving device and transmit the configuration parameters to the parameter setting device. The parameter setting device sets its own operating parameters according to the received configuration parameters. Then, the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C start to operate, so as to realize the variable-frequency power supply FC formed by combining the first sub-variable-frequency power supply A, the second sub-variable-frequency power supply B, and the third sub-variable-frequency power supply C to supply power to the power transformer in the three-phase induction and partial discharge test. According to another embodiment, for example, during the operation of the first sub-variable-frequency power supply A, the sensor of the first sub-variable-frequency power supply A senses its operating parameters and sends the sensed operating parameters to the fault diagnosis device as the monitored operating parameters through the sending device. The fault diagnosis device compares the monitored operating parameters with the threshold preset in the fault diagnosis device. When the difference between the monitored operating parameters and the threshold preset in the fault diagnosis device exceeds a predetermined range (for example, but not limited to, the proportion of the difference to the threshold is greater than ±5%, ±10, ±15%, etc.), it is determined that the first sub-variable-frequency power supply A has a fault. At this time, the fault diagnosis device sends a fault signal to the control unit of the variable-frequency power supply FC. The control unit generates a replacement switch command for controlling the fifth switch K5 to open and the sixth switch K6 to close according to the fault signal and sends it to the actuating device.Then, according to the received replacement switch instruction, the actuating device disconnects the fifth switch K5 corresponding to the first sub-variable frequency power supply A through the fifth switch actuator, and at the same time closes the sixth switch K6 corresponding to the fourth sub-variable frequency power supply D through the sixth switch actuator, so that the first terminal A1 and the second terminal A2 of the first sub-variable frequency power supply A are respectively disconnected from the first output terminal OUT1 and the third output terminal OUT3, and the seventh terminal D1 and the eighth terminal D2 of the fourth sub-variable frequency power supply D are respectively connected to the first output terminal OUT1 and the third output terminal OUT3, so that the fourth sub-variable frequency power supply D can be connected to the variable frequency power supply FC to replace the first sub-variable frequency power supply A. At the same time, according to the received configuration parameters, the fourth sub-variable frequency power supply D completes the setting of its own operating parameters and starts to operate as described above, so that the induction and partial discharge tests of the power transformer can continue.

[0059] Therefore, the variable frequency power supply according to the present invention can not only replace the generator set to perform three-phase or single-phase induction and partial discharge tests on the power transformer, but also be combined according to the test requirements of different test samples to provide power supplies with different capacities. For example, three-phase or single-phase AC output can be realized in various combination ways. For instance, one unit operates and three units are in standby, two units operate in parallel and two units are in standby, three units operate in parallel and one unit is in standby, and four units operate in parallel, so that the equipment can be utilized more reasonably and energy can be saved.

[0060] In summary, the present invention relates to a variable frequency power supply for the induction and partial discharge tests of a power transformer, including: a first sub-variable frequency power supply A, a second sub-variable frequency power supply B, a third sub-variable frequency power supply C, a first output terminal OUT1, a second output terminal OUT2, and a third output terminal OUT3; the first terminal A1 of the first sub-variable frequency power supply is configured to be able to communicate with the first output terminal, and the second terminal A2 is configured to be able to communicate with the second output terminal or the third output terminal; the third terminal B1 of the second sub-variable frequency power supply is configured to be able to communicate with the first output terminal or the second output terminal, and the fourth terminal B2 is configured to be able to communicate with the third output terminal; the fifth terminal C1 of the third sub-variable frequency power supply is configured to be able to communicate with the first output terminal or the third output terminal, and the sixth terminal C2 is configured to be able to communicate with the first output terminal or the third output terminal. Through the technical solution of the present invention, a variable frequency power supply for the induction and partial discharge tests of a power transformer with flexible combination can be realized to meet the power consumption requirements.

[0061] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A variable frequency power supply (FC) for the induction and partial discharge tests of power transformers, characterized in that, The variable frequency power supply (FC) includes: A first sub-variable frequency power supply (A), the first sub-variable frequency power supply (A) including a first terminal (A1) and a second terminal (A2); A second sub-variable frequency power supply (B), the second sub-variable frequency power supply (B) including a third terminal (B1) and a fourth terminal (B2); A third sub-variable frequency power supply (C), the third sub-variable frequency power supply (C) including a fifth terminal (C1) and a sixth terminal (C2); A first output terminal (OUT1); A second output terminal (OUT2); and A third output terminal (OUT3); Wherein, the first sub-variable frequency power supply (A), the second sub-variable frequency power supply (B), and the third sub-variable frequency power supply (C) are respectively configured to output single-phase alternating current after converting the mains power obtained from the public power grid through AC→DC→AC conversion; Wherein, the first output terminal (OUT1), the second output terminal (OUT2), and the third output terminal (OUT3) are respectively configured to be connected to the terminals of the windings of the power transformer; Wherein, the first terminal (A1) is configured to be connectable to the first output terminal (OUT1), the second terminal (A2) is configured to be connectable to the second output terminal (OUT2) or the third output terminal (OUT3), the third terminal (B1) is configured to be connectable to the first output terminal (OUT1) or the second output terminal (OUT2), the fourth terminal (B2) is configured to be connectable to the third output terminal (OUT3), the fifth terminal (C1) is configured to be connectable to the first output terminal (OUT1) or the third output terminal (OUT3), and the sixth terminal (C2) is configured to be connectable to the first output terminal (OUT1) or the third output terminal (OUT3).

2. The variable frequency power supply (FC) according to claim 1, characterized in that, The variable frequency power supply (FC) further includes: A first switch (K1), the first switch (K1) being configured such that when the first switch (K1) is closed, the first terminal (A1) is connected to the first output terminal (OUT1), the third terminal (B1) is connected to the second output terminal (OUT2), and the fifth terminal (C1) is connected to the third output terminal (OUT3); and A second switch (K2), the second switch (K2) being configured such that when the second switch (K2) is closed, the second terminal (A2) is connected to the second output terminal (OUT2), the fourth terminal (B2) is connected to the third output terminal (OUT3), and the sixth terminal (C2) is connected to the first output terminal (OUT1).

3. The variable frequency power supply (FC) according to claim 2, characterized in that, The variable frequency power supply (FC) further includes: A third switch (K3), the third switch (K3) being configured such that when the third switch (K3) is closed, the second terminal (A2) is connected to the third output terminal (OUT3), the fourth terminal (B2) is connected to the third output terminal (OUT3), and the sixth terminal (C2) is connected to the third output terminal (OUT3); and A fourth switch (K4) configured such that when the fourth switch (K4) is closed, the first terminal (A1) is in communication with the first output terminal (OUT1), the third terminal (B1) is in communication with the first output terminal (OUT1), and the fifth terminal (C1) is in communication with the first output terminal (OUT1).

4. The variable frequency power supply (FC) according to claim 3, characterized in that, The variable frequency power supply (FC) further includes: A fifth switch (K5) configured such that when the fifth switch (K5) is closed, the first terminal (A1) is in communication with the first output terminal (OUT1) and the second terminal (A2) is in communication with the third output terminal (OUT3).

5. The variable-frequency power supply (FC) according to claim 4, wherein, The variable frequency power supply (FC) further includes: A fourth sub-variable frequency power supply (D) configured to output single-phase alternating current by subjecting the commercial power obtained from the public power grid to AC→DC→AC conversion, and including a seventh terminal (D1) and an eighth terminal (D2), wherein the seventh terminal (D1) is configured to be capable of being in communication with the first output terminal (OUT1), and the eighth terminal (D2) is configured to be capable of being in communication with the third output terminal (OUT3); and A sixth switch (K6) configured such that when the sixth switch (K6) is closed, the seventh terminal (D1) is in communication with the first output terminal (OUT1) and the eighth terminal (D2) is in communication with the third output terminal (OUT3).

6. The variable frequency power supply (FC) according to claim 5, characterized in that, When the first switch (K1) and the second switch (K2) are closed, the first sub-variable frequency power supply (A), the second sub-variable frequency power supply (B), and the third sub-variable frequency power supply (C) together output three-phase alternating current, wherein the phase angles of the electric powers respectively output by the first sub-variable frequency power supply (A), the second sub-variable frequency power supply (B), and the third sub-variable frequency power supply (C) differ from each other by 120 degrees in sequence.

7. The variable frequency power supply (FC) according to claim 5, characterized in that When the third switch (K3) and the fourth switch (K4) are closed and the first switch (K1) and the second switch (K2) are open, the first sub-variable frequency power supply (A), the second sub-variable frequency power supply (B), and the third sub-variable frequency power supply (C) together output single-phase alternating current, wherein the phase angles of the electric powers respectively output by the first sub-variable frequency power supply (A), the second sub-variable frequency power supply (B), and the third sub-variable frequency power supply (C) are the same.

8. The variable frequency power supply (FC) according to claim 5, characterized in that, When the third switch (K3), the fourth switch (K4), and the fifth switch (K5) are closed and the first switch (K1) and the second switch (K2) are open, the first sub-variable frequency power supply (A), the second sub-variable frequency power supply (B), the third sub-variable frequency power supply (C), and the fourth sub-variable frequency power supply (D) together output single-phase alternating current, and the phase angles of the electric powers respectively output by the first sub-variable frequency power supply (A), the second sub-variable frequency power supply (B), the third sub-variable frequency power supply (C), and the fourth sub-variable frequency power supply (D) are the same.

9. The variable frequency power supply (FC) according to claim 5, characterized in that, When the fifth switch (K5) and the sixth switch (K6) are closed and the first switch (K1), the second switch (K2), the third switch (K3), and the fourth switch (K4) are open, the first sub-inverter power supply (A) and the fourth sub-inverter power supply (D) output single-phase alternating current together, and the phase angles of the power output by the first sub-inverter power supply (A) and the fourth sub-inverter power supply (D) are the same.

10. The variable frequency power supply (FC) according to claim 5, characterized in that, The first sub-inverter power supply (A), the second sub-inverter power supply (B), the third sub-inverter power supply (C), and the fourth sub-inverter power supply (D) respectively include start / stop switches.

11. The variable frequency power supply (FC) according to any one of claims 5 to 10, characterized in that The inverter power supply (FC) further includes an input device, a control unit, and an actuating device. Among them, the input device is configured to receive the power consumption demand input by the user and send the power consumption demand to the control unit; the control unit is configured to receive the power consumption demand and generate a combined switch command for controlling the opening or closing of the first switch (K1), the second switch (K2), the third switch (K3), the fourth switch (K4), the fifth switch (K5), and the sixth switch (K6), as well as the configuration parameters of the first sub-inverter power supply (A), the second sub-inverter power supply (B), the third sub-inverter power supply (C), and the fourth sub-inverter power supply (D), and send the combined switch command to the actuating device and send the configuration parameters to the first sub-inverter power supply (A), the second sub-inverter power supply (B), the third sub-inverter power supply (C), and the fourth sub-inverter power supply (D); the actuating device is configured to receive the combined switch command and cause the first switch (K1), the second switch (K2), the third switch (K3), the fourth switch (K4), the fifth switch (K5), and the sixth switch (K6) to open or close through a first switch actuator, a second switch actuator, a third switch actuator, a fourth switch actuator, a fifth switch actuator, and a sixth switch actuator corresponding to the first switch (K1), the second switch (K2), the third switch (K3), the fourth switch (K4), the fifth switch (K5), and the sixth switch (K6) respectively, so as to connect the terminals of multiple sub-inverter power supplies in the first sub-inverter power supply (A), the second sub-inverter power supply (B), the third sub-inverter power supply (C), and the fourth sub-inverter power supply (D) to the first output terminal (OUT1), the second output terminal (OUT2), and the third output terminal (OUT3), and the multiple connected sub-inverter power supplies set their own operating parameters according to the configuration parameters and start running, thereby combining into the inverter power supply (FC).

12. The variable frequency power supply (FC) according to claim 11, characterized in that, The variable frequency power supply (FC) further includes a fault diagnosis device configured to monitor the operating parameters of the first sub-variable frequency power supply (A), the second sub-variable frequency power supply (B), the third sub-variable frequency power supply (C), and the fourth sub-variable frequency power supply (D), and compare the monitored operating parameters with a threshold value preset in the fault diagnosis device. When the difference between the monitored operating parameters of the first sub-variable frequency power supply (A) and the threshold value exceeds a predetermined range, the fault diagnosis device generates a fault signal and sends the fault signal to the control unit. The control unit generates a replacement switch instruction for controlling the opening or closing of the first switch (K1), the second switch (K2), the third switch (K3), the fourth switch (K4), the fifth switch (K5), and the sixth switch (K6) according to the received fault signal, and sends the replacement switch instruction to the actuating device. The actuating device adjusts the opening or closing of the first switch (K1), the second switch (K2), the third switch (K3), the fourth switch (K4), the fifth switch (K5), and the sixth switch (K6) through the first switch actuator, the second switch actuator, the third switch actuator, the fourth switch actuator, the fifth switch actuator, and the sixth switch actuator respectively, so that the first terminal (A1) and the second terminal (A2) of the first sub-variable frequency power supply (A) are respectively disconnected from the first output terminal (OUT1) and the third output terminal (OUT3), and the seventh terminal (D1) and the eighth terminal (D2) of the fourth sub-variable frequency power supply (D) are respectively connected to the first output terminal (OUT1) and the third output terminal (OUT3).

13. The variable frequency power supply (FC) according to claim 11, characterized in that, Each of the first sub-variable frequency power supply (A), the second sub-variable frequency power supply (B), the third sub-variable frequency power supply (C), and the fourth sub-variable frequency power supply (D) includes a control module, and the control module communicates with the control unit of the variable frequency power supply (FC). Among them, the control module includes a receiving device, a parameter setting device, and a sending device. After the control unit generates the configuration parameters, it sends them to the receiving device, and then the receiving device transmits the configuration parameters to the parameter setting device, and the parameter setting device sets the operating parameters according to the configuration parameters.

Images