A charging start control method, device and equipment of a direct current transformer and a medium

Abstract

The present application relates to the technical field of direct current transformer control strategy, and particularly relates to a charging start control method, device, equipment and medium of a direct current transformer. The direct current transformer comprises a high-voltage bridge arm, a low-voltage bridge arm and a common bridge arm, one of the high-voltage ports and the low-voltage ports formed by the three bridge arms is connected to an external active direct current port; the method comprises: controlling the external active direct current port to charge the two bridge arms corresponding to the connection port; unlocking the two bridge arms and adjusting the modulation ratio of the two bridge arms, and completing the charging of the two bridge arms; controlling the modulation ratio of the two bridge arms to be a sine wave, charging the other bridge arm not connected to the external active direct current port; unlocking the other bridge arm and controlling the modulation ratio of the other bridge arm, and completing the charging of the other bridge arm. Through the implementation of the present application, the charging of each bridge arm of the direct current transformer is realized, and the effective start of the direct current transformer before being connected to the system is ensured.

Description

Technical Field

[0001] This invention relates to the field of DC transformer control strategy technology, specifically to a charging start-up control method, device, equipment, and medium for a DC transformer. Background Technology

[0002] To address global challenges such as climate change and environmental pollution, energy transition, with the primary goal of developing renewable energy and reducing carbon emissions, has become a major direction for energy development in many countries worldwide. Efficient, economical, and reliable grid connection technologies are key to achieving large-scale development of new energy sources such as wind power and solar power.

[0003] Existing offshore wind power grid connection projects primarily employ two technologies: power frequency AC grid connection and flexible DC grid connection. Both technologies utilize AC collection in the wind power aggregation stage. However, due to technical bottlenecks such as the capacitive charging power of submarine cables, a single power frequency AC grid connection project cannot meet the grid connection requirements of offshore wind power. Similarly, applying flexible DC grid connection to offshore wind power also faces challenges such as difficulty in improving AC collection efficiency and the risk of broadband resonance jeopardizing system safety.

[0004] To address the aforementioned issues, in recent years, domestic and international research institutions have proposed offshore wind power DC collection systems based on full DC conversion. From the wind turbine outlet to the collection and transmission links, DC power conversion is used throughout. While taking into account the advantages of flexible DC high-voltage DC transmission technology, it effectively solves many problems caused by AC collection and has become an important development direction for offshore wind power grid connection technology.

[0005] As the core equipment of a full DC convergence system, the DC transformer enables DC voltage transformation and power transmission. Before system startup, the DC transformer needs to be charged for startup. However, current charging startup control is mostly focused on DC transformers that include an intermediate isolation transformer, with less attention paid to charging startup control for DC transformers that do not employ an intermediate isolation transformer. Summary of the Invention

[0006] In view of this, the present invention provides a charging start-up control method, apparatus, equipment and medium for DC transformers, to solve the problem of the lack of charging start-up control for DC transformers without intermediate isolation transformers in the prior art.

[0007] In a first aspect, the present invention provides a charging start-up control method for a DC transformer, the DC transformer including a high-voltage bridge arm, a low-voltage bridge arm, and a common bridge arm. One end of the high-voltage bridge arm is connected to one end of the low-voltage bridge arm and one end of the common bridge arm to form a common point. The other end of the low-voltage bridge arm and the other end of the common bridge arm form a low-voltage port, and the other end of the high-voltage bridge arm and the other end of the common bridge arm form a high-voltage port. The low-voltage port or the high-voltage port is connected to an external active DC port. The method includes: controlling the external active DC port to charge two bridge arms corresponding to the connected ports; unlocking the two bridge arms and adjusting the modulation ratio of the two bridge arms, thus completing the charging of the two bridge arms; controlling the modulation ratio of the two bridge arms to be a sine wave to charge another bridge arm not connected to the external active DC port; unlocking the other bridge arm and controlling the modulation ratio of the other bridge arm to complete the charging of the other bridge arm.

[0008] The charging start-up control method for a DC transformer provided in this invention involves connecting an external active DC port to either the high-voltage or low-voltage port of the DC transformer. The external active DC port charges the two bridge arms corresponding to the connected port. Then, the modulation ratio of the two bridge arms is adjusted to complete the charging process. Subsequently, the modulation ratios of the two bridge arms and another bridge arm are adjusted to complete the charging process of the remaining bridge arm. This achieves charging of all bridge arms of the DC transformer, ensuring effective start-up of the DC transformer before it is connected to the system.

[0009] In one optional implementation, controlling the external active DC port to charge the two bridge arms corresponding to the connection port includes: when the external active DC port is connected to the low-voltage port, controlling the external active DC port to output a rated voltage to charge the low-voltage bridge arm and the common bridge arm to a first voltage value; when the external active DC port is connected to the high-voltage port, controlling the external active DC port to output a rated voltage to charge the high-voltage bridge arm and the common bridge arm to the first voltage value.

[0010] In one optional implementation, the high-voltage bridge arm, the low-voltage bridge arm, and the common bridge arm each include multiple sub-modules, and the first voltage value is the ratio of the rated voltage to the sum of the number of sub-modules in the corresponding two bridge arms.

[0011] In one optional implementation, the two bridge arms are unlocked and their modulation ratios are adjusted to complete charging of the two bridge arms, including: unlocking and controlling the modulation ratio of the two bridge arms to 1; controlling the modulation ratio of the two bridge arms to decrease uniformly to a first threshold and a second threshold, respectively, to complete charging of the two bridge arms.

[0012] In one optional implementation, the first threshold and the second threshold are determined using the following formula:

[0013] (N1*m1+N2*m2)*Uc=U H

[0014] In the formula, N1 and N2 are the number of sub-modules per phase in the two arms, m1 and m2 are the first threshold and the second threshold, respectively, and U H U is the rated voltage of the external active DC port. C This refers to the submodule capacitor voltages of the two bridge arms when charging is complete.

[0015] In one optional implementation, each of the high-voltage arm, the low-voltage arm, and the common arm includes two phases, namely phase A and phase B. Controlling the modulation ratio of the two arms to a sine wave to charge the other arm not connected to an external active DC port includes: unlocking the two arms and controlling their modulation ratio to a sine wave to charge the other arm not connected to an external active DC port; unlocking the other arm and controlling its modulation ratio to complete charging the other arm includes: unlocking and controlling the modulation ratio of phase A in the other arm to 0, locking phase B in the other arm, and completing charging phase B in the other arm; unlocking and controlling the modulation ratio of phase B in the other arm to 0, locking phase A in the other arm, and completing charging phase A in the other arm.

[0016] In one optional implementation, the high-voltage arm, the low-voltage arm, and the common arm each include three phases, namely phase A, phase B, and phase C; controlling the modulation ratio of two arms to a sine wave to charge the other arm not connected to an external active DC port, unlocking the other arm and controlling its modulation ratio to complete charging the other arm, includes: unlocking phases A and B of the two arms and controlling the modulation ratio of phases A and B of the two arms to a sine wave, locking phase C of the two arms, charging phases A and B of the other arm not connected to an external active DC port, unlocking and controlling the modulation ratio of the other arm to complete charging the other arm. The modulation ratio of phases A and C in one arm is 0, phase B in the other arm is locked, and charging of phase B in the other arm is completed; unlock and control the modulation ratio of phases B and C in the other arm to 0, phase A in the other arm is locked, and charging of phase A in the other arm is completed; unlock phases A and C of both arms and control the modulation ratio of phases A and C of the two arms to a sine wave, lock phase B of both arms, charge phase C of the other arm that is not connected to an external active DC port, unlock and control the modulation ratio of phases A and B of the other arm to 0, phase C in the other arm is locked, and charging of phase C in the other arm is completed.

[0017] Secondly, the present invention provides a charging start-up control device for a DC transformer. The DC transformer includes a high-voltage bridge arm, a low-voltage bridge arm, and a common bridge arm. One end of the high-voltage bridge arm is connected to one end of the low-voltage bridge arm and one end of the common bridge arm to form a common point. The other end of the low-voltage bridge arm and the other end of the common bridge arm form a low-voltage port, and the other end of the high-voltage bridge arm and the other end of the common bridge arm form a high-voltage port. The low-voltage port or the high-voltage port is connected to an external active DC port. The device includes: a first charging module for controlling the external active DC port to charge the bridge arm corresponding to the connected port; a second charging module for unlocking the two bridge arms and adjusting the modulation ratio of the two bridge arms, thus completing the charging of the two bridge arms; a third charging module for controlling the modulation ratio of the two bridge arms to a sine wave to charge the other bridge arm not connected to the external active DC port; and a fourth charging module for unlocking the other bridge arm and controlling the modulation ratio of the other bridge arm to complete the charging of the other bridge arm.

[0018] Thirdly, the present invention provides a computer device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the charging start control method for a DC transformer as described in the first aspect or any corresponding embodiment.

[0019] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the charging start control method for a DC transformer according to the first aspect or any corresponding embodiment described above. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic flowchart of a charging start-up control method for a DC transformer according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of a DC transformer according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of the full-bridge submodule according to an embodiment of the present invention;

[0024] Figure 4This is a schematic diagram of the structure of a half-bridge submodule according to an embodiment of the present invention;

[0025] Figure 5 This is a structural block diagram of a charging start control device for a DC transformer according to an embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] According to an embodiment of the present invention, a charging start-up control method for a DC transformer is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0029] This embodiment provides a charging start-up control method for a DC transformer, which can be used in electronic devices. The DC transformer includes a high-voltage bridge arm, a low-voltage bridge arm, and a common bridge arm. One end of the high-voltage bridge arm is connected to one end of the low-voltage bridge arm and one end of the common bridge arm to form a common point. The other end of the low-voltage bridge arm and the other end of the common bridge arm form a low-voltage port. The other end of the high-voltage bridge arm and the other end of the common bridge arm form a high-voltage port. The low-voltage port or the high-voltage port is connected to an external active DC port. Figure 1 This is a flowchart of a charging start-up control method for a DC transformer according to an embodiment of the present invention, such as... Figure 1 As shown, the process includes the following steps:

[0030] Step S101 involves controlling the external active DC port to charge the two bridge arms corresponding to the connection port. Specifically, the DC transformer includes a high-voltage bridge arm, a low-voltage bridge arm, and a common bridge arm, which are connected to form a high-voltage port and a low-voltage port. In application, the high-voltage port is connected to an external high-voltage source, and the external high-voltage voltage is transformed through the three bridge arms to output a low voltage from the low-voltage port; or the low-voltage port is connected to an external low-voltage source, and the external low-voltage voltage is transformed through the three bridge arms to output a high voltage from the high-voltage port. Therefore, this DC transformer does not include an intermediate isolation transformer; voltage transformation is achieved solely through the three bridge arms.

[0031] This DC transformer includes at least two phases. Figure 2 Taking phase A and phase B as an example, the DC transformer includes two common points, A and B. Each of the three arms—the high-voltage arm, the low-voltage arm, and the common arm—includes a certain number of sub-modules SM. Each arm also contains an arm reactor. These sub-modules can be as follows: Figure 3 The full-bridge submodule shown can also be as follows: Figure 4 The half-bridge submodule shown. When charging the bridge arm, the capacitors in the submodule are mainly charged.

[0032] Before charging, all three bridge arms are in a locked state. When charging and starting the DC transformer is required, an external active DC port can be connected to either the high-voltage or low-voltage port. The output voltage of the active DC port charges the sub-modules in the two bridge arms corresponding to the connected ports until the voltage stabilizes. Specifically, when charging the two bridge arms connected to the external active DC port, both bridge arms are locked and the voltage of the sub-modules is zero. Since the sub-module trigger circuit usually obtains power through capacitor voltage division, the IGBTs in the sub-modules will lock due to insufficient trigger energy. Therefore, the capacitors can only be charged first through the diodes connected in anti-parallel with the IGBTs within the sub-modules.

[0033] Step S102: Unlock the two bridge arms and adjust their modulation ratios. Charging of the two bridge arms is then complete. The voltage output from the external active DC port is insufficient to charge the voltage of the two bridge arms to a stable operating state. Specifically, when the sub-modules in the two bridge arms are charged to a stable voltage, the IGBT becomes controllable and can be unlocked. This unlocks the two bridge arms, and the modulation ratio of the two bridge arms is adjusted, i.e., the ratio of the number of sub-modules in each bridge arm to the total number of sub-modules in that arm. This ensures that the sub-module capacitor voltages of the two bridge arms are ultimately charged to a stable operating state, completing the charging of the two bridge arms.

[0034] Step S103: Control the modulation ratio of the two bridge arms to a sine wave to charge the other bridge arm that is not connected to the external active DC port. Specifically, after the two bridge arms are charged, the other bridge arm is charged. If the external active DC port is connected to a high-voltage port, the other bridge arm is a low-voltage bridge arm; if the external active DC port is connected to a low-voltage port, the other bridge arm is a high-voltage bridge arm. If the other bridge arm is a low-voltage bridge arm, the modulation ratio of the high-voltage bridge arm and the common bridge arm is controlled to a sine wave to charge the low-voltage bridge arm. At this time, the low-voltage bridge arm can be charged to half of the stable operating voltage.

[0035] Step S104: Unlock the other bridge arm and control its modulation ratio to complete charging. Specifically, charging of each phase in the other bridge arm can be completed by sequentially locking one phase and unlocking the other phases. When unlocking other phases, the modulation ratio of the other phases can be controlled to 0, meaning the number of submodules in the other phases is 0, thus completing charging of the locked phase.

[0036] After charging the high-voltage arm, low-voltage arm, and common arm, all arms are locked and await connection to the DC system.

[0037] The charging start-up control method for a DC transformer provided in this invention involves connecting an external active DC port to either the high-voltage or low-voltage port of the DC transformer. The external active DC port charges the two bridge arms corresponding to the connected port. Then, the modulation ratio of the two bridge arms is adjusted to complete the charging process. Subsequently, the modulation ratios of the two bridge arms and another bridge arm are adjusted to complete the charging process of the remaining bridge arm. This achieves charging of all bridge arms of the DC transformer, ensuring effective start-up of the DC transformer before it is connected to the system.

[0038] This embodiment provides a charging start-up control method for a DC transformer, the process of which includes the following steps:

[0039] Step S201: Control the external active DC port to charge the two bridge arms corresponding to the connection port.

[0040] Specifically, step S201 includes:

[0041] Step S2011: When the external active DC port is connected to the low-voltage port, the external active DC port is controlled to output a rated voltage to charge the low-voltage bridge arm and the common bridge arm to a first voltage value. The first voltage value is the ratio of the rated voltage to the sum of the number of submodules in the corresponding two bridge arms. Specifically, the first voltage value is represented as U. H / (N l +N w ), where U H The rated voltage of the external active DC port, N l Sum represents the number of submodules per phase in the low-voltage bridge arm, N. w This represents the number of each phase submodule in the common bridge arm.

[0042] Step S2012: When the external active DC port is connected to the high-voltage port, control the external active DC port to output the rated voltage to charge the high-voltage bridge arm and the common bridge arm to a first voltage value. Specifically, the first voltage value is represented as U. H / (N h +N w ), where Nh This represents the number of submodules per phase in the high-voltage bridge arm.

[0043] Step S202: Unlock the two bridge arms and adjust the modulation ratio of the two bridge arms. The charging of the two bridge arms is then complete.

[0044] Specifically, step S202 includes:

[0045] Step S2021: Unlock and control the modulation ratio of the two bridge arms to 1; wherein, controlling the modulation ratio of the two bridge arms to 1 means controlling the sub-modules in both bridge arms to be engaged.

[0046] Step S2022: Control the modulation ratios of the two bridge arms to decrease uniformly to a first threshold and a second threshold, respectively, thus completing the charging of the two bridge arms. The first threshold and the second threshold are determined using the following formula:

[0047] (N1*m1+N2*m2)*Uc=U H

[0048] In the formula, N1 and N2 are the number of sub-modules per phase in the two arms, m1 and m2 are the first threshold and the second threshold, respectively, and U H U is the rated voltage of the external active DC port. C This refers to the submodule capacitor voltages of the two bridge arms when charging is complete.

[0049] Wherein, when the two bridge arms are a high-voltage bridge arm and a common bridge arm, N1 and N2 are the number of sub-modules per phase in the high-voltage bridge arm and the common bridge arm, respectively, and m1 and m2 are the modulation ratios of the high-voltage bridge arm and the common bridge arm, respectively; when the two bridge arms are a low-voltage bridge arm and a common bridge arm, N1 and N2 are the number of sub-modules per phase in the low-voltage bridge arm and the common bridge arm, respectively, and m1 and m2 are the modulation ratios of the low-voltage bridge arm and the common bridge arm, respectively; specifically, by uniformly reducing the modulation ratios of the two bridge arms to the first threshold and the second threshold according to the above formula, that is, reducing the number of sub-modules put into the two bridge arms, the capacitor voltage of the sub-modules of the two bridge arms can be charged to the stable operating voltage U. C .

[0050] Step S203: Control the modulation ratio of the two bridge arms to a sine wave to charge the other bridge arm that is not connected to an external active DC port; for details, please refer to [link to relevant documentation]. Figure 1 Step S103 of the illustrated embodiment will not be described again here.

[0051] Step S204: Unlock the other bridge arm and control its modulation ratio to complete charging. See details below. Figure 1 Step S104 of the illustrated embodiment will not be described again here.

[0052] This embodiment provides a charging start-up control method for a DC transformer, which includes the following steps:

[0053] Step S301: Control the external active DC port to charge the two bridge arms corresponding to the connection port; for details, please refer to [link to relevant documentation]. Figure 1 Step S101 of the illustrated embodiment will not be described again here.

[0054] Step S302: Unlock the two bridge arms and adjust the modulation ratio of the two bridge arms. Charging of the two bridge arms is now complete. For details, please refer to [link to relevant documentation]. Figure 1 Step S102 of the illustrated embodiment will not be described again here.

[0055] Step S303: Control the modulation ratio of the two bridge arms to a sine wave to charge the other bridge arm that is not connected to an external active DC port.

[0056] Specifically, when each of the high-voltage arm, low-voltage arm, and common arm includes two phases, step S303 above includes:

[0057] Step S3031: Unlock two bridge arms and control the modulation ratio of the two bridge arms to a sine wave to charge the other bridge arm that is not connected to an external active DC port. Specifically, unlock two phases of the two bridge arms that have completed charging, and control the modulation ratio of each bridge arm to a sine wave. At this time, the voltage difference between the common points A and B formed by phases A and B is a sine wave, and the amplitude of this sine wave is equal to the number of sub-modules per phase and the voltage U in the other bridge arm. C The product of these two values ​​can charge the voltage of the other arm neutron module to Uc / 2.

[0058] Step S304: Unlock the other bridge arm and control the modulation ratio of the other bridge arm to complete the charging of the other bridge arm.

[0059] Specifically, step S304 includes:

[0060] Step S3041: Unlock and control the modulation ratio of phase A in the other bridge arm to 0, lock phase B in the other bridge arm, and complete the charging of phase B in the other bridge arm, that is, charge phase B in the other bridge arm to Uc.

[0061] Step S3042: Unlock and control the modulation ratio of phase B in the other bridge arm to 0, lock phase A in the other bridge arm, and complete the charging of phase A in the other bridge arm, that is, charge phase A in the other bridge arm to Uc.

[0062] It should be noted that there is no sequential relationship between steps S3041 and S3042. Step S3041 can be executed first, or step S3042 can be executed first, and the charging of the other bridge arm can be completed in either case.

[0063] This embodiment provides a charging start-up control method for a DC transformer, which includes the following steps:

[0064] Step S401: Control the external active DC port to charge the two bridge arms corresponding to the connection port; for details, please refer to [link to relevant documentation]. Figure 1 Step S101 of the illustrated embodiment will not be described again here.

[0065] Step S402: Unlock the two bridge arms and adjust their modulation ratios. Charging of the two bridge arms is now complete. For details, please refer to [link to relevant documentation]. Figure 1 Step S102 of the illustrated embodiment will not be described again here.

[0066] Step S403: Control the modulation ratio of the two bridge arms to a sine wave to charge the other bridge arm that is not connected to an external active DC port.

[0067] Step S404: Unlock the other bridge arm and control the modulation ratio of the other bridge arm to complete the charging of the other bridge arm.

[0068] Specifically, when each of the high-voltage arm, low-voltage arm, and common arm includes three phases A, B, and C, the above steps S403 and S404 include:

[0069] Step S4041: Unlock phases A and B of the two bridge arms and control the modulation ratio of phases A and B of the two bridge arms to a sine wave; lock phase C of the two bridge arms; charge phases A and B of the other bridge arm that is not connected to an external active DC port; unlock and control the modulation ratio of phases A and C in the other bridge arm to 0; lock phase B in the other bridge arm; complete charging phase B in the other bridge arm; unlock and control the modulation ratio of phases B and C in the other bridge arm to 0; lock phase A in the other bridge arm; complete charging phase A in the other bridge arm.

[0070] Specifically, any two phases of the two bridge arms that have completed charging are unlocked, and the modulation ratio of each bridge arm is controlled to be a sine wave. At this time, the voltage difference between the two common points formed by these two phases is a sine wave, and the amplitude of this sine wave is equal to the number of sub-modules per phase and the voltage U in the other bridge arm. C The product of these two phases can charge the voltage of the corresponding two-phase submodule in the other arm to Uc / 2. Then, the corresponding two phases in the other arm are separately locked and charged until both phases are charged to Uc.

[0071] Step S4042: Unlock phases A and C of the two bridge arms and control the modulation ratio of phases A and C of the two bridge arms to a sine wave. Lock phase B of the two bridge arms. Charge phase C of the other bridge arm that is not connected to an external active DC port. Unlock and control the modulation ratio of phases A and B in the other bridge arm to 0. Lock phase C in the other bridge arm. The charging of phase C in the other bridge arm is complete. Specifically, after two phases, such as phases A and B, in the other bridge arm are fully charged, unlock two phases, such as phases A and C or phases B and C (as long as phase C is included), in the two bridge arms that have been fully charged, so that the modulation ratio of these two phases is a sine wave, thereby charging phase C in the other bridge arm to Uc / 2. Then lock phase C in the other bridge arm and charge it until phase C is charged to Uc.

[0072] It should be noted that since phases A, B, and C are identical phase units, when three phases are included, phases A and B of two bridge arms can be unlocked first, i.e., the charging of the other bridge arm can be completed using the steps S4041 and S4041 described above; alternatively, phases A and C of two bridge arms can be unlocked first, phases A and C can be charged first, and then phase B can be charged; or phases B and C can be unlocked first, phases B and C can be charged first, and then phase A can be charged.

[0073] As a specific application embodiment of the present invention, the DC transformer consists of three arms: a high-voltage arm H, a low-voltage arm L, and a common arm W. Each arm has two phases, A and B. The number of sub-modules in the high-voltage arm H, the low-voltage arm L, and the common arm W are 180, 50, and 100, respectively. The rated voltage of the high-voltage port is 320kV, and the rated voltage of the low-voltage port is 100kV. During steady-state operation, the capacitor voltage of each arm sub-module is 2kV. The initial state of the DC transformer is that all arms are in a locked state, and the capacitor voltage of all sub-modules is 0.

[0074] Taking charging from the high-voltage port as an example (the principle of charging from the low-voltage port is the same as that of charging from the high-voltage port, but the low-voltage port needs to be connected to an external active DC port, and the charging order of the high-voltage bridge arm H and the low-voltage bridge arm L in the following steps should be interchanged), the specific starting control method of the DC transformer is as follows:

[0075] (1) When T = 0s, connect the high-voltage port of the DC transformer to the external 320kV active DC port to charge the submodule capacitors of the high-voltage bridge arm H and the common bridge arm W.

[0076] (2) T = 0.5s, unlock the high voltage bridge arm H and the common bridge arm W. When unlocking, control the modulation ratio of the high voltage bridge arm H and the common bridge arm W to be 1.

[0077] (3) T = 0.5s - 1s, control the modulation ratio of the high voltage bridge arm H to decrease from 1 to 0.65 at a constant speed, control the modulation ratio of the common bridge arm W to decrease from 1 to 0.43 at a constant speed, charge the capacitor voltage of the high voltage bridge arm H and the common bridge arm W to 2kV, and the charging of the high voltage bridge arm H and the common bridge arm W is completed.

[0078] (4) T = 1s, control the modulation ratio of the high voltage bridge arm H and the common bridge arm W to be a sine wave, so that the voltage difference between the common points A and B is a sine wave, and the amplitude of this sine wave is 100kV. This process can charge the voltage of the low voltage bridge arm L submodule to 1kV.

[0079] (5) T = 2s, unlock phase A of low voltage bridge arm L, control the modulation ratio of phase A of low voltage bridge arm L to 0, phase B of low voltage bridge arm L continues to be locked, the voltage of the capacitor of phase B submodule of low voltage bridge arm L is charged to 2kV, and the charging of phase B of low voltage bridge arm L is completed.

[0080] (6) T = 2.2s, lock the A phase of the low-voltage bridge arm L, unlock the B phase of the low-voltage bridge arm L, control the modulation ratio of the B phase of the low-voltage bridge arm L to 0, charge the capacitor voltage of the A phase submodule of the low-voltage bridge arm L to 2kV, and the charging of the A phase of the low-voltage bridge arm L is completed.

[0081] (7) T = 2.4s, all bridge arm sub-modules of the DC transformer have completed charging, and all bridge arms are locked, waiting to be connected to the DC system.

[0082] This embodiment also provides a charging start-up control device for a DC transformer, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0083] This embodiment provides a charging start-up control device for a DC transformer. The DC transformer includes a high-voltage bridge arm, a low-voltage bridge arm, and a common bridge arm. One end of the high-voltage bridge arm connects to one end of the low-voltage bridge arm and one end of the common bridge arm to form a common point. The other end of the low-voltage bridge arm and the other end of the common bridge arm form a low-voltage port, and the other end of the high-voltage bridge arm and the other end of the common bridge arm form a high-voltage port. The low-voltage port or the high-voltage port is connected to an external active DC port. Figure 5 As shown, the device includes:

[0084] The first charging module 501 is used to control the external active DC port to charge the two bridge arms corresponding to the connection port;

[0085] The second charging module 502 is used to unlock the two bridge arms and adjust the modulation ratio of the two bridge arms, so that the charging of the two bridge arms is completed.

[0086] The third charging module 503 is used to control the modulation ratio of the two bridge arms to a sine wave and to charge the other bridge arm that is not connected to an external active DC port.

[0087] The fourth charging module 504 is used to unlock another bridge arm and control the modulation ratio of the other bridge arm to complete the charging of the other bridge arm.

[0088] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0089] This invention also provides a computer device having the above-described features. Figure 5 The shown is a charging start control device for a DC transformer.

[0090] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 6 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 6 Take a processor 10 as an example.

[0091] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0092] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0093] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device as shown by a landing page for an app. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, which can be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0094] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0095] The computer device also includes a communication interface 30 for communicating with other devices or communication networks.

[0096] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0097] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A charging start-up control method for a DC transformer, characterized in that, The DC transformer includes a high-voltage bridge arm, a low-voltage bridge arm, and a common bridge arm. One end of the high-voltage bridge arm is connected to one end of the low-voltage bridge arm and one end of the common bridge arm to form a common point. The other end of the low-voltage bridge arm and the other end of the common bridge arm form a low-voltage port, and the other end of the high-voltage bridge arm and the other end of the common bridge arm form a high-voltage port. The low-voltage port or the high-voltage port is connected to an external active DC port. The method includes: Control the external active DC port to charge the two bridge arms corresponding to the connection port; Unlock the two bridge arms and adjust the modulation ratio of the two bridge arms. The charging of the two bridge arms is then complete. The modulation ratio of the two bridge arms is controlled to be a sine wave to charge the other bridge arm that is not connected to an external active DC port; Unlock the other bridge arm and control its modulation ratio to complete charging. The high-voltage bridge arm, the low-voltage bridge arm, and the common bridge arm each include two phases, namely phase A and phase B; Controlling the modulation ratio of the two bridge arms to a sine wave to charge the other bridge arm that is not connected to an external active DC port includes: Unlock two bridge arms and control the modulation ratio of the two bridge arms to a sine wave to charge the other bridge arm that is not connected to an external active DC port; Unlocking the other bridge arm and controlling its modulation ratio to complete charging includes: Unlock and control the modulation ratio of phase A in another bridge arm to 0, lock phase B in another bridge arm, and complete the charging of phase B in another bridge arm; Unlock and control the modulation ratio of phase B in the other bridge arm to 0, lock phase A in the other bridge arm, and complete the charging of phase A in the other bridge arm.

2. A charging start-up control method for a DC transformer, characterized in that, The DC transformer includes a high-voltage bridge arm, a low-voltage bridge arm, and a common bridge arm. One end of the high-voltage bridge arm is connected to one end of the low-voltage bridge arm and one end of the common bridge arm to form a common point. The other end of the low-voltage bridge arm and the other end of the common bridge arm form a low-voltage port, and the other end of the high-voltage bridge arm and the other end of the common bridge arm form a high-voltage port. The low-voltage port or the high-voltage port is connected to an external active DC port. The method includes: Control the external active DC port to charge the two bridge arms corresponding to the connection port; Unlock the two bridge arms and adjust the modulation ratio of the two bridge arms. The charging of the two bridge arms is then complete. The modulation ratio of the two bridge arms is controlled to be a sine wave to charge the other bridge arm that is not connected to an external active DC port; Unlock the other bridge arm and control its modulation ratio to complete charging. The high-voltage bridge arm, the low-voltage bridge arm, and the common bridge arm all include three phases, namely phase A, phase B, and phase C; Controlling the modulation ratio of the two bridge arms to a sine wave, charging the other bridge arm that is not connected to an external active DC port, unlocking the other bridge arm and controlling its modulation ratio to complete the charging of the other bridge arm, includes: Unlock phases A and B of two bridge arms and control the modulation ratio of phases A and B of the two bridge arms to a sine wave; lock phase C of the two bridge arms; charge phases A and B of the other bridge arm that is not connected to an external active DC port; unlock and control the modulation ratio of phases A and C of the other bridge arm to 0; lock phase B of the other bridge arm; charging phase B of the other bridge arm is complete; unlock and control the modulation ratio of phases B and C of the other bridge arm to 0; lock phase A of the other bridge arm; charging phase A of the other bridge arm is complete. Unlock phases A and C of two bridge arms and control the modulation ratio of phases A and C of the two bridge arms to a sine wave. Lock phase B of the two bridge arms. Charge phase C of the other bridge arm that is not connected to an external active DC port. Unlock and control the modulation ratio of phases A and B in the other bridge arm to 0. Lock phase C in the other bridge arm. The charging of phase C in the other bridge arm is completed.

3. The method according to claim 1 or 2, characterized in that, Controlling the external active DC port to charge the two bridge arms corresponding to the connection port includes: When the external active DC port is connected to the low-voltage port, the external active DC port is controlled to output the rated voltage to charge the low-voltage bridge arm and the common bridge arm to the first voltage value. When the external active DC port is connected to the high voltage port, the external active DC port is controlled to output the rated voltage to charge the high voltage bridge arm and the common bridge arm to the first voltage value.

4. The method according to claim 3, characterized in that, The high-voltage bridge arm, the low-voltage bridge arm, and the common bridge arm each include multiple sub-modules, and the first voltage value is the ratio of the rated voltage to the sum of the number of sub-modules in the corresponding two bridge arms.

5. The method according to claim 4, characterized in that, Unlock the two bridge arms and adjust their modulation ratios. Charging of the two bridge arms is then complete, including: Unlock and control the modulation ratio of the two bridge arms to 1; The modulation ratios of the two bridge arms are controlled to decrease uniformly to the first threshold and the second threshold, respectively, and the charging of the two bridge arms is completed.

6. The method according to claim 5, characterized in that, The first threshold and the second threshold are determined using the following formula: (N1 m1+N2 m2) Uc=U H In the formula, N1 and N2 are the number of sub-modules per phase in the two arms, m1 and m2 are the first threshold and the second threshold, respectively, and U H U is the rated voltage of the external active DC port. C This refers to the submodule capacitor voltages of the two bridge arms when charging is complete.

7. A charging start-up control device for a DC transformer, used to implement the charging start-up control method for a DC transformer as described in any one of claims 1 to 6, characterized in that, The DC transformer includes a high-voltage bridge arm, a low-voltage bridge arm, and a common bridge arm. One end of the high-voltage bridge arm is connected to one end of the low-voltage bridge arm and one end of the common bridge arm to form a common point. The other end of the low-voltage bridge arm and the other end of the common bridge arm form a low-voltage port, and the other end of the high-voltage bridge arm and the other end of the common bridge arm form a high-voltage port. The low-voltage port or the high-voltage port is connected to an external active DC port. The device includes: The first charging module is used to control the external active DC port to charge the two bridge arms corresponding to the connection port; The second charging module is used to unlock the two bridge arms and adjust the modulation ratio of the two bridge arms, after which the charging of the two bridge arms is completed. The third charging module is used to control the modulation ratio of the two bridge arms to a sine wave and to charge the other bridge arm that is not connected to an external active DC port. The fourth charging module is used to unlock another bridge arm and control the modulation ratio of the other bridge arm to complete the charging of the other bridge arm.

8. A computer device, characterized in that, include: The system includes a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes the computer instructions to perform the charging start-up control method for a DC transformer as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the charging start-up control method for the DC transformer according to any one of claims 1 to 6.

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