Solid-state transformer in-grid operations and maintenance circuit and method therefor, controller, and storage medium

Abstract

Embodiments of the present disclosure provide a solid-state transformer in-grid operations and maintenance circuit and a method therefor, a controller, and a storage medium. The solid-state transformer in-grid operations and maintenance circuit comprises solid-state transformer units, input side switches, output side switches, and an auxiliary energy charging loop; the input side of each solid-state transformer unit is connected to an input bus, and the output side is connected to an output bus; the input side switches are arranged on the input sides of the solid-state transformer units, and the output side switches are arranged on the output sides of the solid-state transformer units; one solid-state transformer unit corresponds to one input side switch and one output side switch; and a voltage output end of the auxiliary energy charging loop is connected between the solid-state transformer units and the output side switches. When a solid-state transformer unit needs to be maintained or replaced, the input side switches and the output side switches of some of the solid-state transformer units can be disconnected, and since the decrease in system capacity is small, the system can still operate normally; additionally, the solid-state transformer units are charged by means of the auxiliary energy charging loop, so that the inputs and outputs of the units are restored in a surge-free manner.

Description

Solid-state transformer on-line operation and maintenance circuit and method, controller and storage medium

[0001] Cross-references to related publications

[0002] The present disclosure is based on Chinese Patent Publication No. 202410039187X filed on January 9, 2024, entitled “Solid-state transformer on-line operation and maintenance circuit, method, controller and storage medium thereof”, and claims the priority of the patent disclosure, and all the contents disclosed therein are incorporated into the present disclosure by reference. Technical Field

[0003] The embodiments of the present disclosure relate to the technical field of transformer power distribution, and in particular to an on-line operation and maintenance circuit for a solid-state transformer and a method thereof, a controller, and a storage medium. Background Art

[0004] In the relevant technologies, in the fields of data centers and power distribution, the power supply system needs to have high-reliability operation capabilities. On-line operation and maintenance of equipment is one of the key technologies to improve operational reliability. However, solid-state transformers involve medium-voltage systems and power electronic modules, and there is currently no good on-line operation and maintenance solution, which affects reliable operation. Summary of the Invention

[0005] Embodiments of the present disclosure provide a solid-state transformer on-line operation and maintenance circuit and method, a controller, and a storage medium.

[0006] In a first aspect, an embodiment of the present disclosure provides an on-line operation and maintenance circuit for a solid-state transformer, comprising: a solid-state transformer cell, wherein the input side is configured to be connected to an input bus, and the output side is configured to be connected to an output bus; an input side switch and an output side switch, wherein the input side switch is arranged between the input side of the solid-state transformer cell and the input bus, and the output side switch is arranged between the output side of the solid-state transformer cell and the output bus; wherein a plurality of the solid-state transformer cells, the input side switches, and the output side switches are provided, and one solid-state transformer cell corresponds to one input side switch and one output side switch; an auxiliary charging circuit, wherein the voltage output end of the auxiliary charging circuit is connected between the solid-state transformer cell and the output side switch, and is configured to charge the solid-state transformer cell.

[0007] In a second aspect, an embodiment of the present disclosure provides an on-line operation and maintenance method for a solid-state transformer, which is applied to the on-line operation and maintenance circuit of the solid-state transformer in the first aspect above. The on-line operation and maintenance method for the solid-state transformer includes: receiving an operation and maintenance shutdown instruction, and determining a corresponding target solid-state transformer cell according to the operation and maintenance shutdown instruction; disconnecting the input side switch and the output side switch corresponding to the target solid-state transformer cell to control the shutdown of the target solid-state transformer cell, and maintaining power supply to the load through the solid-state transformer cells other than the target solid-state transformer cell; after the target solid-state transformer cell completes operation and maintenance, controlling the auxiliary charging circuit to charge the target solid-state transformer cell, closing the input side switch and closing the output side switch.

[0008] In a third aspect, an embodiment of the present disclosure provides a controller comprising: at least one processor; at least one memory configured to store at least one program; and at least one of the programs executing the solid-state transformer in-network operation and maintenance method of the second aspect mentioned above when the at least one processor runs the program.

[0009] In a fourth aspect, an embodiment of the present disclosure provides a computer-readable storage medium storing a program executable by a processor, wherein the program executable by the processor executes the solid-state transformer in-network operation and maintenance method of the second aspect described above when the program is executed by the processor.

[0010] In a fifth aspect, an embodiment of the present disclosure provides a computer program product, comprising a computer program or computer instructions, characterized in that the computer program or the computer instructions are stored in a computer-readable storage medium, a processor of a computer device reads the computer program or the computer instructions from the computer-readable storage medium, and the processor executes the computer program or the computer instructions, so that the computer device executes the solid-state transformer on-line operation and maintenance method of the second aspect mentioned above. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG1 is a schematic structural diagram of an on-line operation and maintenance circuit for a solid-state transformer provided by one embodiment of the present disclosure;

[0012] FIG2 is a schematic structural diagram of an on-line operation and maintenance circuit for a solid-state transformer provided by another embodiment of the present disclosure;

[0013] FIG3 is a schematic structural diagram of an on-line operation and maintenance circuit for a solid-state transformer provided by another embodiment of the present disclosure;

[0014] FIG4 is a schematic structural diagram of a bridge isolation module of a solid-state transformer in a network operation and maintenance circuit according to an embodiment of the present disclosure;

[0015] FIG5 is a flowchart of the steps of a method for online operation and maintenance of a solid-state transformer provided by one embodiment of the present disclosure;

[0016] FIG6 is a flowchart of the steps of a method for online operation and maintenance of a solid-state transformer provided by another embodiment of the present disclosure;

[0017] FIG7 is a flowchart of a method for operating and maintaining a solid-state transformer in an online manner according to another embodiment of the present disclosure;

[0018] FIG8 is a flowchart of the steps of a method for online operation and maintenance of a solid-state transformer provided by another embodiment of the present disclosure;

[0019] FIG9 is a flowchart of a method for operating and maintaining a solid-state transformer in an online manner according to another embodiment of the present disclosure;

[0020] FIG10 is a schematic structural diagram of a controller configured to execute an on-line operation and maintenance method for a solid-state transformer, provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not intended to limit the present disclosure.

[0022] It should be noted that although the device schematics illustrate functional module divisions and the flowcharts illustrate logical sequences, in certain circumstances, the steps shown or described may be performed in a sequence that differs from the module divisions in the device or the sequence in the flowcharts. The terms "first," "second," and so on, in the specification, claims, and drawings, are used to distinguish similar items and are not necessarily used to describe a specific sequence or precedence.

[0023] In the embodiments of the present disclosure, words such as "further," "exemplarily," or "optionally" are used to indicate examples, illustrations, or descriptions and should not be interpreted as being more preferred or advantageous over other embodiments or designs. The use of words such as "further," "exemplarily," or "optionally" is intended to present related concepts in a concrete manner.

[0024] In some cases, data centers and power distribution require power supply systems with high reliability. On-line equipment operation and maintenance is a key technology for improving operational reliability. However, solid-state transformers (SSTs) involve medium-voltage systems and power electronics modules, and currently lack a robust on-line operation and maintenance solution, impacting reliable operation.

[0025] Currently, in the existing technology, the power supply system of the data center adopts a power supply and distribution system based on an uninterruptible power supply (UPS). The UPS is composed of multiple power modules connected in parallel to realize load power supply. In order to realize on-line operation and maintenance, the UPS adopts a maintenance bypass method to realize load maintenance without power outage. Its working principle is that during maintenance, the maintenance bypass is turned on, and the load is powered by the AC power provided by the maintenance bypass. The input and output switches of the UPS module are disconnected to achieve voltage isolation. Under this condition, the UPS performs operation and maintenance operations. After the operation and maintenance is completed, the UPS uses phase-locked technology to achieve impact-free restoration to the grid and complete the load transfer. After that, the maintenance bypass is disconnected to restore the original state. Therefore, on-line operation and maintenance need to solve two problems: module voltage isolation and impact-free recovery.

[0026] With the advancement of power electronics and power distribution technology, solid-state transformers have been introduced into data center power supply systems. However, when the SSTs undergo maintenance, their output power is interrupted, which violates power supply reliability requirements. A conventional solution is to add an additional power supply, shut down the SSTs during maintenance, and switch to a backup circuit to achieve SST outage maintenance. However, this solution requires a dedicated power supply system with the same capacity as the SSTs, resulting in high costs and a large footprint.

[0027] Based on the above situation, the embodiment of the present disclosure proposes a solution that can realize the on-line operation and maintenance of solid-state transformers, solve the core problems of on-line operation and maintenance such as power transmission bypass channel, power module isolation and impact-free recovery, reduce costs, and improve equipment reliability.

[0028] The following further describes various embodiments of the solid-state transformer in-network operation and maintenance circuit according to the present disclosure in conjunction with the accompanying drawings.

[0029] As shown in FIG1 , FIG1 is a structural diagram of an on-line operation and maintenance circuit of a solid-state transformer provided by an embodiment of the present disclosure.

[0030] In one embodiment, the solid-state transformer network operation and maintenance circuit includes but is not limited to a solid-state transformer unit 100, an input-side switch 210, an output-side switch 220, and an auxiliary charging circuit, wherein multiple solid-state transformer units 100, input-side switches 210, and output-side switches 220 are provided, and one solid-state transformer unit 100 corresponds to one input-side switch 210 and one output-side switch 220.

[0031] Specifically, the input side of the solid-state transformer monomer 100 is connected to the input bus 310 through the input side switch 210, and the output side of the solid-state transformer monomer 100 is connected to the output bus 320 through the output side switch 220; the voltage output end of the auxiliary charging circuit is respectively connected between each solid-state transformer monomer 100 and each output side switch 220, and is configured to charge each solid-state transformer monomer 100.

[0032] It should be noted that the solid-state transformer unit 100 mentioned above refers to a solid-state transformer. A solid-state transformer is a modern electrical energy device that provides bidirectional power flow. It is a static electrical device that combines power electronics conversion technology with high-frequency power conversion technology based on the principle of electromagnetic induction. An SST integrates electrical isolation, voltage conversion, and reactive power compensation. By integrating traditional transformers and power electronics, it can enhance the intelligence of power grid equipment.

[0033] In one embodiment, the voltage on the input side of the solid-state transformer unit 100 , ie, the input bus 310 , is an AC voltage; and the voltage on the output side of the solid-state transformer unit 100 , ie, the output bus 320 , is a DC voltage.

[0034] It is worth noting that since the solid-state transformer on-line operation and maintenance circuit of the embodiment of the present disclosure is composed of multiple solid-state transformer monomers 100 connected in parallel, when some solid-state transformer monomers 100 need to be repaired or replaced, the embodiment of the present disclosure can disconnect the input side switches 210 and output side switches 220 of some solid-state transformer monomers 100. Since the decrease in system capacity is small, the system can still operate normally. In addition, the embodiment of the present disclosure can also charge the solid-state transformer monomers 100 through the auxiliary charging circuit, so that the input and output of the solid-state transformer monomers 100 can be restored without impact. Therefore, the embodiment of the present disclosure can realize the on-line operation and maintenance of the solid-state transformer, and can also ensure the reliability of the solid-state transformer on-line operation and maintenance.

[0035] In one embodiment, the auxiliary charging circuit includes but is not limited to an operation and maintenance voltage output device 400 and an operation and maintenance switch 500. One end of the operation and maintenance switch 500 is connected to the operation and maintenance voltage output device 400, and the other end is connected between the solid-state transformer cell 100 and the output side switch 220. There are multiple operation and maintenance switches 500, and one operation and maintenance switch 500 corresponds to one solid-state transformer cell 100.

[0036] Specifically, in order to be able to power the solid-state transformer cell 100 after the solid-state transformer cell 100 is repaired or replaced, the embodiment of the present disclosure is correspondingly provided with an operation and maintenance voltage output device 400, and the voltage is output to the solid-state transformer cell 100 through the operation and maintenance voltage output device 400; in addition, during the maintenance or replacement of the solid-state transformer cell 100, the operation and maintenance switch 500 needs to be disconnected; after the maintenance or replacement of the solid-state transformer cell 100 is completed, the operation and maintenance switch 500 needs to be closed to power the solid-state transformer cell 100.

[0037] It should be noted that the above-mentioned operation and maintenance voltage output device 400 may include but is not limited to the following three structural forms, which are specifically as follows:

[0038] The first structural form, as shown in Figure 1, the operation and maintenance voltage output device 400 includes but is not limited to a power transformer TR1 and a first voltage converter DY1. The input end of the power transformer TR1 is configured to be connected to the input bus 310, and the output end is connected to multiple operation and maintenance switches 500 through the first voltage converter DY1. The first voltage converter DY1 is configured to convert AC voltage into DC voltage.

[0039] Specifically, the embodiment of the present disclosure can obtain and output AC power from the input bus 310 through the power transformer TR1, and transmit the AC power to the input side of the first voltage converter DY1; then, the first voltage converter DY1 will convert the AC power into DC power, and supply the DC power to the solid-state transformer unit 100 through the operation and maintenance switch 500.

[0040] It's important to note that the power transformer TR1 is a special transformer whose primary function is to extract electrical energy from the power system and supply it to the load after conversion. The power transformer TR1 typically performs voltage conversion, electrical isolation, and power transmission functions, and is widely used in various power systems and electronic equipment.

[0041] In addition, it should be noted that both the input side and the output side of the power transformer TR1 are AC power, wherein the power transformer TR1 can adjust the amplitude of the AC power or not, that is, the AC voltage on the input side of the power transformer TR1 can be equal to the AC voltage on the output side of the power transformer TR1 or not, and the embodiments of the present disclosure do not make specific limitations on this.

[0042] The second structural form is shown in Figure 2, which is a structural diagram of the solid-state transformer on-line operation and maintenance circuit provided by another embodiment of the present disclosure; the operation and maintenance voltage output device 400 includes but is not limited to a second voltage converter DY2, the input end of the second voltage converter DY2 is configured to be connected to the output bus 320, and the output end is connected to multiple operation and maintenance switches 500, and the second voltage converter DY2 is configured to convert the numerical value of the DC voltage of the output bus 320.

[0043] Specifically, the embodiment of the present disclosure can obtain direct current from the output bus 320 through the second voltage converter DY2, then convert the voltage value of the direct current, and supply the converted direct current to the solid-state transformer unit 100 through the operation and maintenance switch 500.

[0044] In one embodiment, as shown in FIG2 , the operation and maintenance voltage output device 400 further includes but is not limited to an operation and maintenance power supply switch Ks, one end of the operation and maintenance power supply switch Ks is connected to the output bus 320 , and the other end is connected to the second voltage converter DY2 .

[0045] Specifically, when the second voltage converter DY2 is needed to supply power, the operation and maintenance power supply switch Ks can be closed so that the second voltage converter DY2 can obtain DC power from the output bus 320; when the second voltage converter DY2 is not needed to supply power, the operation and maintenance power supply switch Ks can be disconnected.

[0046] The third structural form is shown in Figure 3, which is a structural diagram of the solid-state transformer on-line operation and maintenance circuit provided by another embodiment of the present disclosure; the operation and maintenance voltage output device 400 includes but is not limited to a power supply battery 600 and a third voltage converter DY3, the input end of the third voltage converter DY3 is connected to the power supply battery 600, and the output end is connected to multiple operation and maintenance switches 500, and the third voltage converter DY3 is configured to convert the numerical value of the DC voltage of the power supply battery 600.

[0047] Specifically, the embodiment of the present disclosure can additionally set up a power supply battery 600, obtain DC power from the power supply battery 600 through the third voltage converter DY3, then convert the voltage value of the DC power, and supply the converted DC power to the solid-state transformer unit 100 through the operation and maintenance switch 500.

[0048] In one embodiment, as shown in FIG3 , the operation and maintenance voltage output device 400 further includes but is not limited to an operation and maintenance power supply switch Ks, one end of the operation and maintenance power supply switch Ks is connected to the power supply battery 600 , and the other end is connected to the third voltage converter DY3 .

[0049] Specifically, when the third voltage converter DY3 is needed to supply power, the operation and maintenance power switch Ks can be closed so that the third voltage converter DY3 can obtain DC power from the power supply battery 600; when the third voltage converter DY3 is not needed to supply power, the operation and maintenance power switch Ks can be disconnected.

[0050] In one embodiment, as shown in Figure 4, Figure 4 is a structural diagram of a bridge isolation module of a solid-state transformer in a network operation and maintenance circuit provided by an embodiment of the present disclosure; the solid-state transformer monomer 100 includes but is not limited to a bridge isolation module, and the bridge isolation module includes but is not limited to a high-voltage side cascade module 110 and a low-voltage side cascade module 120. The high-voltage side cascade module 110 is provided with a high-voltage side capacitor 111, and the low-voltage side cascade module 120 is provided with a low-voltage side capacitor 121. The high-voltage side capacitor 111 is connected to the input side switch 210, and the low-voltage side capacitor 121 is connected to the output side switch 220 and the operation and maintenance switch 500.

[0051] Based on the hardware structure of the solid-state transformer on-line operation and maintenance circuit of each of the above embodiments, the overall embodiments of the solid-state transformer on-line operation and maintenance circuit of the present disclosure are respectively proposed below.

[0052] In one embodiment, the SST machine is designed to consist of N SST monomers connected in parallel. Switches are added to the input and output of each SST monomer to achieve voltage isolation and ensure that the overall input and output are not out of power. The network operation and maintenance loop is designed to enable all isolated branches to obtain energy. As shown in Figures 1 to 4, the SST machine is changed from a whole to a plurality of monomers connected in parallel, such as SST1-SSTN, which consists of N in total. When the SSTN needs to be operated and maintained, KMN1 and KMN2 are disconnected. Since the input and output are disconnected, the single SSTN will not be powered and can be operated and maintained. Since the overall system has multiple branches in parallel, it will not affect the operation of the system. After the operation and maintenance is completed, the auxiliary charging circuit can be used to complete the impact-free recovery of the entire system.

[0053] Specifically, as shown in Figures 1 to 4, if the SSTN requires maintenance, the SSTN is shut down, KMN1 and KMN2 are disconnected, and a module is replaced. After the replacement is complete, KMN3 is closed, outputting voltage and charging the SSTN low-voltage capacitors. Once the SSTN low-voltage capacitors are charged, the SST internally activates and charges the SSTN high-voltage capacitors. When the voltage on the high-voltage capacitors exceeds the peak grid voltage, KMN1 is closed. Because the high-voltage capacitor voltage is higher than the grid voltage, a bumpless grid connection is achieved, eliminating the medium-voltage grid connection surge. This current surge would affect designs like SST1 that are still operating, and in severe cases, could cause the system to trip, making live maintenance impossible. After KMN1 is closed, KMN3 is disconnected, and the SSTN starts to establish output voltage. The established SSTN voltage VN is adjusted. When the voltage difference between VN and the existing output voltage Vdc falls below a specified value, KMN2 is closed. Because the voltage difference between VN and Vdc is small, a bumpless grid connection is achieved. After the above process is completed, SSTN returns to normal state and online operation and maintenance are realized. The overall operation and maintenance process does not affect load work.

[0054] Based on the above embodiments, the technical solutions of the embodiments of the present disclosure include but are not limited to the following technical effects:

[0055] First, by disconnecting some SST inputs and outputs, the system output capacity only drops by 1 / N, and the output can still operate normally. The system backup capacity is reduced to 1 / N of the system capacity, and the input and output are both restored without impact, which does not affect the load operation. Therefore, the backup system cost is low.

[0056] Second, since the operation and maintenance loop only charges the capacitor, the required capacity is very small, generally only less than 2% of the SST monomer capacity, and each branch can be charged through a multi-way switch. Therefore, the auxiliary loop capacity is only 1 / (50N) of the system capacity, and the circuit implementation cost is low.

[0057] Based on the solid-state transformer on-line operation and maintenance circuits of the above-mentioned embodiments, various embodiments of the solid-state transformer on-line operation and maintenance method of the embodiments of the present disclosure are respectively proposed below.

[0058] As shown in Figure 5, Figure 5 is a flow chart of a solid-state transformer on-line operation and maintenance method provided by an embodiment of the present disclosure; the solid-state transformer on-line operation and maintenance method can be applied to the solid-state transformer on-line operation and maintenance circuit of the above embodiment, including but not limited to step S510, step S520 and step S530.

[0059] Step S510: receiving an operation and maintenance shutdown instruction, and determining a corresponding target solid-state transformer monomer according to the operation and maintenance shutdown instruction;

[0060] Step S520: disconnecting the input-side switch and the output-side switch corresponding to the target solid-state transformer monomer to control the target solid-state transformer monomer to shut down, and maintaining power supply to the load through the solid-state transformer monomers other than the target solid-state transformer monomer;

[0061] Step S530: After the target solid-state transformer unit completes operation and maintenance, the auxiliary charging circuit is controlled to charge the target solid-state transformer unit, and the input side switch and the output side switch are closed.

[0062] In one embodiment, first, after receiving the operation and maintenance shutdown instruction corresponding to the target solid-state transformer cell, the embodiment of the present disclosure will disconnect the input side switch and the output side switch corresponding to the target solid-state transformer cell, so that the target solid-state transformer cell is not powered and can be operated and maintained; at the same time, it is also necessary to keep the solid-state transformer cells other than the target solid-state transformer cell running to maintain power supply to the load; after the target solid-state transformer cell is repaired or replaced, the target solid-state transformer cell can be charged through the auxiliary charging circuit first, and then the input side switch and the output side switch are closed in sequence, thereby achieving impact-free grid connection of the output and input of the target solid-state transformer cell.

[0063] It is worth noting that since the solid-state transformer on-line operation and maintenance circuit of the embodiment of the present disclosure is composed of multiple solid-state transformer units connected in parallel, when some solid-state transformer units need to be repaired or replaced, the embodiment of the present disclosure can disconnect the input-side switches and output-side switches of some solid-state transformer units. Since the decrease in system capacity is small, the system can still operate normally. In addition, the embodiment of the present disclosure can also charge the solid-state transformer units through the auxiliary charging circuit, so that the input and output of the solid-state transformer units can be restored without impact. Therefore, the embodiment of the present disclosure can realize the on-line operation and maintenance of the solid-state transformer, and can also ensure the reliability of the solid-state transformer on-line operation and maintenance.

[0064] In addition, as shown in FIG6 , FIG6 is a flow chart of a solid-state transformer network operation and maintenance method provided by another embodiment of the present disclosure; regarding the control of the auxiliary charging circuit in the above-mentioned step S530 to charge the target solid-state transformer monomer, including but not limited to step S610 and step S620.

[0065] Step S610: closing the operation and maintenance switch corresponding to the target solid-state transformer;

[0066] Step S620: Control the operation and maintenance voltage output device to charge the low-voltage side capacitor and the high-voltage side capacitor in the target solid-state transformer monomer through the operation and maintenance switch.

[0067] In one embodiment, after the target solid-state transformer cell is repaired or replaced, the operation and maintenance switch corresponding to the target solid-state transformer cell can be closed, and the low-voltage side capacitor in the target solid-state transformer cell can be charged through the auxiliary charging circuit. Since the bridge isolation module has bidirectional energy flow capability, its high-voltage side capacitor can obtain energy from the low-voltage side capacitor. Therefore, the auxiliary charging circuit can indirectly realize the high-voltage side capacitor in the target solid-state transformer cell; then, the input side switch and the output side switch are closed in sequence, thereby realizing the impact-free grid connection of the output and input of the target solid-state transformer cell.

[0068] In addition, as shown in FIG7 , FIG7 is a flow chart of a solid-state transformer network operation and maintenance method provided by another embodiment of the present disclosure; regarding the closed input side switch in the above step S530 , it includes but is not limited to step S710 and step S720 .

[0069] Step S710: obtaining the voltage value of the high-voltage side capacitor;

[0070] Step S720: When the voltage value of the high-voltage side capacitor is greater than the peak value of the grid voltage, close the input side switch corresponding to the target solid-state transformer monomer.

[0071] In one embodiment, for the specific process of closing the input side switch mentioned above, in order to achieve impact-free grid connection of the input of the target solid-state transformer monomer, it is necessary to first obtain the voltage value of the high-voltage side capacitor, and then compare the voltage value of the high-voltage side capacitor with the peak voltage of the grid. If the voltage value of the high-voltage side capacitor is greater than the peak voltage of the grid, the corresponding input side switch can be closed, thereby achieving impact-free grid connection of the input of the target solid-state transformer monomer.

[0072] In addition, as shown in FIG8 , FIG8 is a flowchart of a solid-state transformer on-line operation and maintenance method provided by another embodiment of the present disclosure; after the above-mentioned step S720, the solid-state transformer on-line operation and maintenance method of the embodiment of the present disclosure further includes but is not limited to step S810 and step S820.

[0073] Step S810: disconnecting the operation and maintenance switch corresponding to the target solid-state transformer;

[0074] Step S820: Start the target solid-state transformer unit.

[0075] In one embodiment, after the input-side switch is closed, the corresponding operation and maintenance switch may be opened, and the target solid-state transformer unit may be started, thereby starting to establish the output voltage.

[0076] In addition, as shown in FIG9 , FIG9 is a flow chart of a solid-state transformer in-network operation and maintenance method provided by another embodiment of the present disclosure; regarding the closed output side switch in the above-mentioned step S530 , it includes but is not limited to step S910 , step S920 and step S930 .

[0077] Step S910: Acquire the single-unit output voltage of the output side of the target solid-state transformer single unit and the busbar output voltage of the output busbar;

[0078] Step S920: determining the voltage difference between the cell output voltage and the bus output voltage;

[0079] Step S930: When the voltage difference is less than a preset threshold, close the output-side switch corresponding to the target solid-state transformer monomer.

[0080] In one embodiment, for the specific process of closing the output-side switch described above, in order to achieve impact-free grid connection of the output of the target solid-state transformer cell, it is necessary to first obtain the cell output voltage of the output side of the target solid-state transformer cell and the bus output voltage of the output bus. Then, the cell output voltage and the bus output voltage are compared, and the voltage difference between the two is calculated. If the voltage difference is less than a preset threshold, that is, the magnitude of the voltage difference is not large, the corresponding output-side switch can be closed, thereby achieving impact-free grid connection of the output of the target solid-state transformer cell.

[0081] Based on the solid-state transformer on-line operation and maintenance methods of the above-mentioned embodiments, overall embodiments of the solid-state transformer on-line operation and maintenance methods of the embodiments of the present disclosure are respectively proposed below.

[0082] In one embodiment, as shown in FIG1 , the components of the solid-state transformer in the network operation and maintenance circuit are described as follows:

[0083] SST1-SSTN are multiple SST monomers connected in parallel, which are composed of multiple SST modules cascaded to realize medium-voltage AC to low-voltage DC conversion; KM11-KMN1 are medium-voltage AC switches, which are set to control whether to disconnect the AC input of each group of SST monomers; KM12-KMN2 are low-voltage DC switches, which are set to control whether to disconnect the DC output of each group of SST monomers; KM13-KMN3 are operation and maintenance switches, which are set to control the capacitor charging of the required circuits; V1-VN is a voltage detection circuit, which detects the output voltage of each SST unit; TR1 is the power transformer of the operation and maintenance circuit, which is set to draw power from medium voltage; DY1 is the operation and maintenance circuit power supply, that is, the first voltage converter, which realizes the conversion of AC power into DC power.

[0084] In one embodiment, taking SSTN as an example, the network operation and maintenance steps are as follows:

[0085] 1. Normal operation: During normal operation, multiple SSTs are connected in parallel to output to the load.

[0086] 2. Single SSTN Shutdown: Based on maintenance requirements, shut down the SST unit requiring maintenance. Send a command to trip input KMN1 and output switch KMN2 to shut down the unit's input and output. Because the SST is composed of multiple units, shutting down a single SST unit will allow the output to remain normal, and the load can operate normally.

[0087] 3. Module replacement in SSTN: Replace the modules that require operation and maintenance in SSTN.

[0088] 4. Start the auxiliary power supply DY1: Close the auxiliary power switch KMN3 and start the auxiliary power rectifier DY1 to establish the DC voltage.

[0089] 5. Charging the High-Voltage-Side Capacitor of an SST Cell: Based on the SST cell topology, each cell is composed of a high-frequency isolation module. The circuit is shown in Figure 4. The low-voltage-side capacitor is charged by the DY1 output. The cascaded H-bridge is activated. Because the high-frequency isolation module has bidirectional energy flow capability, its high-voltage-side capacitor can draw energy from the low-voltage-side capacitor. Because both the AC and DC switches are disconnected at this time, the required charging energy is very small. The charging process ends when the capacitor voltage of the high-voltage-side cascaded module exceeds the peak grid voltage.

[0090] 6. Close the SSTN single-unit medium-voltage switch KMN1: After charging is complete, the single-unit system performs a low-voltage wave self-test (traditional self-tests require the high-voltage system to be powered on). Because the high-voltage side is not connected to the grid, a failure in the wave self-test will not impact the grid. After the self-test is complete, since the sum of the voltage capacity of the SST single-unit cascade modules exceeds the peak grid voltage, a non-impact grid connection can be achieved. At this point, the medium-voltage switch KMN1 can be closed, and a non-impact grid connection can be achieved.

[0091] 7. Auxiliary power supply DY1 shuts down: After the SSTN single medium-voltage side switch KMN1 is closed, the auxiliary power supply DY1 shuts down and the auxiliary power supply output switch KMN3 is disconnected.

[0092] 8. SSTN single unit start: After the auxiliary power is disconnected, the SSTN single unit starts.

[0093] 9. Impact-free grid connection on the DC side: The established voltage VN is adjusted, and VN is compared with the existing output bus voltage Vdc. When the voltage difference is less than the set value, KMN2 is closed. Because the voltage difference between VN and Vdc is very small, impact-free grid connection of the output is achieved.

[0094] After completing the above steps, SSTN resumes operation and the SST completes online operation and maintenance.

[0095] Based on the solid-state transformer on-line operation and maintenance methods of the above-mentioned embodiments, various embodiments of the controller, solid-state transformer system, power supply system, computer-readable storage medium and computer program product of the embodiments of the present disclosure are respectively proposed below.

[0096] As shown in Figure 10, Figure 10 is a schematic diagram of the structure of a controller configured to execute a method for in-network operation and maintenance of a solid-state transformer, according to one embodiment of the present disclosure. The controller 600 implemented in the present disclosure includes a processor 610, a memory 620, and a computer program stored in the memory 620 and executable on the processor 610. Figure 10 illustrates one processor 610 and one memory 620 as an example.

[0097] The processor 610 and the memory 620 may be connected via a bus or other means. FIG10 takes the bus connection as an example.

[0098] The memory 620, as a non-transitory computer-readable storage medium, can be configured to store non-transitory software programs and non-transitory computer executable programs. In addition, the memory 620 may include a high-speed random access memory and may also include a non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 620 may optionally include a memory 620 remotely located relative to the processor 610, and these remote memories 620 may be connected to the controller 600 via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0099] Those skilled in the art will appreciate that the device structure shown in FIG. 10 does not limit the controller 600 , and may include more or fewer components than shown, or combine certain components, or arrange the components differently.

[0100] In the controller 600 shown in FIG10 , the processor 610 can be configured to call a solid-state transformer on-line operation and maintenance program stored in the memory 620 to implement the above-described solid-state transformer on-line operation and maintenance method. Specifically, the non-transient software program and instructions required to implement the solid-state transformer on-line operation and maintenance method of the above-described embodiment are stored in the memory 620. When executed by the processor 610, the solid-state transformer on-line operation and maintenance method of the above-described embodiment is executed.

[0101] It is worth noting that since the controller 600 of the embodiment of the present disclosure can execute the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments, the specific implementation methods and technical effects of the controller 600 of the embodiment of the present disclosure can refer to the specific implementation methods and technical effects of the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments.

[0102] In addition, an embodiment of the present disclosure further provides a solid-state transformer system, which includes the solid-state transformer on-line operation and maintenance circuit or controller of the above-mentioned embodiment.

[0103] It is worth noting that since the solid-state transformer system of the embodiment of the present disclosure includes the solid-state transformer on-line operation and maintenance circuit or controller of the above-mentioned embodiment, and the controller of the above-mentioned embodiment can execute the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments, the specific implementation methods and technical effects of the solid-state transformer system of the embodiment of the present disclosure can refer to the specific implementation methods and technical effects of the solid-state transformer on-line operation and maintenance circuit or the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments.

[0104] In addition, an embodiment of the present disclosure further provides a power supply system, which includes the solid-state transformer system of the above embodiment.

[0105] It is worth noting that since the power supply system of the embodiment of the present disclosure includes the solid-state transformer system of the above-mentioned embodiment, and the solid-state transformer system of the above-mentioned embodiment includes the solid-state transformer on-line operation and maintenance circuit or controller of the above-mentioned embodiment, and the controller of the above-mentioned embodiment can execute the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments, therefore, the specific implementation methods and technical effects of the power supply system of the embodiment of the present disclosure can refer to the specific implementation methods and technical effects of the solid-state transformer on-line operation and maintenance circuit or the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments.

[0106] In addition, an embodiment of the present disclosure further provides a computer-readable storage medium storing computer-executable instructions for executing the above-described solid-state transformer in-network operation and maintenance method. For example, the method steps described above in Figures 5 to 9 are executed.

[0107] It is worth noting that since the computer-readable storage medium of the embodiment of the present disclosure can execute the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments, the specific implementation methods and technical effects of the computer-readable storage medium of the embodiment of the present disclosure can refer to the specific implementation methods and technical effects of the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments.

[0108] Those skilled in the art will appreciate that all or some of the steps and systems in the method disclosed above can be implemented as software, firmware, hardware, and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor, or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, and the computer-readable medium can include computer storage media (or non-transitory media) and communication media (or temporary media). As known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory, or other memory technology, CD-ROM, digital versatile disks (DVD), or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage, or other magnetic storage devices, or any other medium that can be configured to store desired information and can be accessed by a computer. Furthermore, as is well known to those skilled in the art, communication media typically includes computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0109] In addition, an embodiment of the present disclosure also provides a computer program product, including a computer program or computer instructions, wherein the computer program or computer instructions are stored in a computer-readable storage medium, a processor of a computer device reads the computer program or computer instructions from the computer-readable storage medium, and the processor executes the computer program or computer instructions, so that the computer device executes the method steps in Figures 5 to 9 described above.

[0110] It is worth noting that since the computer program product of the embodiment of the present disclosure can execute the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments, the specific implementation methods and technical effects of the computer program product of the embodiment of the present disclosure can refer to the specific implementation methods and technical effects of the solid-state transformer on-line operation and maintenance method of any of the above-mentioned embodiments.

[0111] The above is a specific description of the preferred implementation of the present disclosure, but the present disclosure is not limited to the above implementation. Technical personnel familiar with the art can also make various equivalent modifications or substitutions under the shared conditions that do not violate the spirit of the present disclosure. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present disclosure.

Claims

1. An on-site operation and maintenance circuit for a solid-state transformer, comprising: A solid-state transformer unit, with its input side configured to be connected to an input busbar and its output side configured to be connected to an output busbar; An input-side switch and an output-side switch, where the input-side switch is disposed between the input side of the solid-state transformer unit and the input busbar, and the output-side switch is disposed between the output side of the solid-state transformer unit and the output busbar; wherein, there are multiple of the solid-state transformer units, the input-side switches, and the output-side switches, and one solid-state transformer unit corresponds to one input-side switch and one output-side switch; An auxiliary charging circuit, with its voltage output terminal connected between the solid-state transformer unit and the output-side switch, configured to charge the solid-state transformer unit.

2. The on-grid operation and maintenance circuit of the solid-state transformer according to claim 1, wherein, The auxiliary charging circuit includes an operation and maintenance voltage output device and an operation and maintenance switch. One end of the operation and maintenance switch is connected to the operation and maintenance voltage output device, and the other end is connected between the solid-state transformer unit and the output-side switch. There are multiple operation and maintenance switches, and one operation and maintenance switch corresponds to one solid-state transformer unit.

3. The on-grid operation and maintenance circuit of the solid-state transformer according to claim 2, wherein, The operation and maintenance voltage output device includes a power-taking transformer and a first voltage converter. The input end of the power-taking transformer is configured to be connected to the input busbar, and the output end is connected to multiple operation and maintenance switches through the first voltage converter. The first voltage converter is configured to convert an AC voltage into a DC voltage.

4. The on-grid operation and maintenance circuit of the solid-state transformer according to claim 2, wherein, The operation and maintenance voltage output device includes a second voltage converter. The input end of the second voltage converter is configured to be connected to the output busbar, and the output end is connected to multiple operation and maintenance switches. The second voltage converter is configured to convert the value of the DC voltage of the output busbar.

5. The in-network operation and maintenance circuit of the solid-state transformer according to claim 4, wherein, The operation and maintenance voltage output device further includes an operation and maintenance power supply switch. One end of the operation and maintenance power supply switch is connected to the output busbar, and the other end is connected to the second voltage converter.

6. The on-network operation and maintenance circuit of the solid-state transformer according to claim 2, wherein, The operation and maintenance voltage output device includes a power supply battery and a third voltage converter. The input end of the third voltage converter is connected to the power supply battery, and the output end is connected to multiple operation and maintenance switches. The third voltage converter is configured to convert the value of the DC voltage of the power supply battery.

7. The on-grid operation and maintenance circuit of the solid-state transformer according to claim 6, wherein, The operation and maintenance voltage output device further includes an operation and maintenance power supply switch. One end of the operation and maintenance power supply switch is connected to the power supply battery, and the other end is connected to the third voltage converter.

8. The in-network operation and maintenance circuit of the solid-state transformer according to any one of claims 2 to 7, wherein, The solid-state transformer unit includes a bridge isolation module, which includes a high-voltage side cascaded module and a low-voltage side cascaded module. The high-voltage side cascaded module is provided with high-voltage side capacitors, and the low-voltage side cascaded module is provided with low-voltage side capacitors. The high-voltage side capacitors are connected to the input-side switch, and the low-voltage side capacitors are connected to the output-side switch and the operation and maintenance switch.

9. An on-site operation and maintenance method for a solid-state transformer, applied to the on-site operation and maintenance circuit for a solid-state transformer according to any one of claims 1 to 8, the on-site operation and maintenance method for a solid-state transformer includes: Receiving an operation and maintenance shutdown instruction, and determining a corresponding target solid-state transformer unit according to the operation and maintenance shutdown instruction; Disconnect the input - side switch and the output - side switch corresponding to the target solid - state transformer unit to control the target solid - state transformer unit to shut down, and maintain power supply to the load through the solid - state transformer units other than the target solid - state transformer unit; After the target solid - state transformer unit completes operation and maintenance, control the auxiliary charging circuit to charge the target solid - state transformer unit, and close the input - side switch and the output - side switch.

10. The method for on-grid operation and maintenance of the solid-state transformer according to claim 9, wherein, The auxiliary charging circuit includes an operation - and - maintenance voltage output device and an operation - and - maintenance switch. The operation - and - maintenance voltage output device is connected between the solid - state transformer unit and the output - side switch through the operation - and - maintenance switch; Controlling the auxiliary charging circuit to charge the target solid - state transformer unit includes: Closing the operation - and - maintenance switch corresponding to the target solid - state transformer unit to charge the low - voltage - side capacitor and the high - voltage - side capacitor in the target solid - state transformer unit.

11. The on-grid operation and maintenance method of the solid-state transformer according to claim 10, wherein, The closing of the input - side switch includes: Obtain the voltage value of the high - voltage - side capacitor; When the voltage value of the high - voltage - side capacitor is greater than the peak value of the grid voltage, close the input - side switch corresponding to the target solid - state transformer unit.

12. The method for on-network operation and maintenance of the solid-state transformer according to claim 11, wherein, After closing the input - side switch corresponding to the target solid - state transformer unit, the on - grid operation - and - maintenance method of the solid - state transformer further includes: Disconnect the operation - and - maintenance switch corresponding to the target solid - state transformer unit and start the target solid - state transformer unit.

13. The on-grid operation and maintenance method of the solid-state transformer according to claim 9, wherein, The closing of the output - side switch includes: Obtain the single - unit output voltage of the output side of the target solid - state transformer unit and the bus output voltage of the output bus; Determine the voltage difference between the single - unit output voltage and the bus output voltage; When the voltage difference is less than a preset threshold, close the output - side switch corresponding to the target solid - state transformer unit.

14. A controller, comprising: At least one processor; At least one memory configured to store at least one program; When at least one of the at least one program is run by at least one of the at least one processor, it executes the on - grid operation - and - maintenance method of the solid - state transformer according to any one of claims 9 to 13.

15. A computer - readable storage medium, in which a program executable by a processor is stored. When the program executable by the processor is run by the processor, it executes the on - grid operation - and - maintenance method of the solid - state transformer according to any one of claims 9 to 13.

16. A computer program product, including a computer program or computer instructions. The computer program or the computer instructions are stored in a computer - readable storage medium. A processor of a computer device reads the computer program or the computer instructions from the computer - readable storage medium, and the processor executes the computer program or the computer instructions, so that the computer device executes the on - grid operation - and - maintenance method of the solid - state transformer according to any one of claims 9 to 13.

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