Method and system for determining submodule type of bridge-arm multiplexing dc transformer

Abstract

The application relates to a bridge arm multiplexing type direct current transformer submodule type determination method and system. The method comprises the following steps: acquiring system parameters, direct current voltages of multiple bridge arms, and alternating current voltage amplitudes of multiple bridge arm connection points; based on the system parameters, the bridge arm current of each bridge arm is calculated; when the maximum value of the bridge arm current of each bridge arm is less than or equal to the maximum utilization current of an IGBT in the bridge arm multiplexing type direct current transformer, the bridge arm submodule type of each bridge arm in the bridge arm multiplexing type direct current transformer is determined based on the bridge arm current of each bridge arm, the direct current voltage and the alternating current voltage amplitude. The method can determine the configuration type of each bridge arm submodule of the bridge arm multiplexing type direct current transformer under different working conditions, simultaneously reduces the equipment cost of the direct current transformer, and ensures good economic benefits.

Description

Technical Field

[0001] This invention relates to the field of DC power grid technology, and specifically to a method and system for determining the submodule type of a bridge arm multiplexed DC transformer. Background Technology

[0002] As a crucial component of DC transmission systems, DC transformers perform functions such as DC voltage conversion, renewable energy aggregation and transmission, system power flow control, and fault current limiting. The bridge arm reuse type, a type of DC transformer topology, has become the mainstream topology due to its advantages such as eliminating the need for an intermediate frequency isolation transformer, requiring fewer submodules, and strong engineering applicability. However, a systematic method for determining the configuration of each bridge arm submodule in this topology is currently lacking. Especially under high transformer ratio conditions, due to the limitations of the low-voltage port voltage level, there is an urgent need to propose a method for configuring the bridge arm submodules of the bridge arm reuse type DC transformer that can meet both economic efficiency and high-capacity transmission requirements. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention proposes a method for determining the submodule type of a bridge arm reuse type DC transformer, the method comprising:

[0004] Obtain the system parameters of the bridge arm multiplexed DC transformer, the DC voltage of multiple bridge arms in the bridge arm multiplexed DC transformer, and the AC voltage amplitude of multiple bridge arm connection points;

[0005] Based on the system parameters, the bridge arm current of each bridge arm is calculated;

[0006] When the maximum value of the bridge arm current in each bridge arm is less than or equal to the maximum utilization current of the IGBT in the bridge arm reuse DC transformer, the bridge arm submodule type of each bridge arm in the bridge arm reuse DC transformer is determined based on the bridge arm current and DC voltage of each bridge arm and the AC voltage amplitude.

[0007] Optionally, determining the bridge arm submodule type of each bridge arm in the bridge arm multiplexed DC transformer based on the bridge arm current and DC voltage of each bridge arm and the AC voltage amplitude includes:

[0008] The difference between the DC voltage and the AC voltage amplitude of each bridge arm is calculated to obtain the voltage difference value of each bridge arm;

[0009] Based on the voltage difference and current of each bridge arm, the bridge arm submodule type of each bridge arm in the bridge arm multiplexed DC transformer is determined.

[0010] Optionally, determining the bridge arm submodule type of each bridge arm in the bridge arm multiplexed DC transformer based on the voltage difference and bridge arm current of each bridge arm includes:

[0011] When the voltage difference is greater than or equal to zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm sub-module type of the bridge arm in the bridge arm multiplexed DC transformer is determined to be a full bridge type; if the minimum value of the bridge arm current is less than zero, the bridge arm sub-module type of the bridge arm in the bridge arm multiplexed DC transformer is determined to be a half bridge type.

[0012] When the voltage difference is less than zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a full-bridge type; if the current difference is less than zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a hybrid type.

[0013] Optionally, after determining that the bridge arm submodule type of the bridge arm in the bridge arm multiplexed DC transformer is a hybrid type, the method further includes:

[0014] Based on the DC voltage of the bridge arm, the AC voltage amplitude, and the rated voltage of the bridge arm submodule, the number of full-bridge submodules in the hybrid type is calculated.

[0015] Optionally, the calculation method for the number of full-bridge sub-modules in the hybrid type satisfies the following inequality:

[0016]

[0017] Where, N 全 U represents the number of full-bridge submodules in the hybrid configuration. ac U represents the amplitude of AC voltage. dc U represents the DC voltage of the bridge arm. capN This represents the rated voltage of the bridge arm submodule, and this represents the rounding function, which rounds up.

[0018] Optionally, the system parameters include high-voltage port voltage, low-voltage port voltage, transmission capacity, number of phases, and number of poles;

[0019] The calculation of the bridge arm current for each bridge arm based on the system parameters includes:

[0020] Based on the high-voltage port voltage, the low-voltage port voltage, the transmission capacity, the number of phases, and the number of poles, the DC current component and AC current component of each bridge arm are calculated.

[0021] The DC current component and AC current component of each bridge arm are superimposed to obtain the bridge arm current of each bridge arm.

[0022] Optionally, the plurality of bridge arms are high-voltage bridge arms, multiplex bridge arms, and low-voltage bridge arms;

[0023] The calculation of the DC current component and AC current component of each bridge arm based on the high-voltage port voltage, the low-voltage port voltage, the transmission capacity, the number of phases, and the number of poles includes:

[0024] Based on the high-voltage port voltage, the transmission capacity, the number of phases, and the number of poles, the DC current component of the high-voltage bridge arm is calculated;

[0025] Based on the effective value of AC voltage, power factor angle, voltage of the high-voltage port, voltage of the low-voltage port, and DC current component of the high-voltage bridge arm at multiple bridge arm connection points, the AC current component of the high-voltage bridge arm is calculated using the energy balance principle of the high-voltage bridge arm.

[0026] Based on the low-voltage port voltage, the transmission capacity, the number of phases, the number of poles, and the number of low-voltage ports, the DC current component of the low-voltage bridge arm is calculated.

[0027] Based on the DC current component of the low-voltage bridge arm, the AC current component of the low-voltage bridge arm is determined using the energy balance principle of the low-voltage bridge arm.

[0028] The DC current component of the multiplexed bridge arm is calculated based on the DC current component of the high-voltage bridge arm, the DC current component of the low-voltage bridge arm, and the number of low-voltage ports.

[0029] The AC current component of the multiplexed bridge arm is calculated based on the low-voltage port voltage, the DC current component of the multiplexed bridge arm, the effective value of the AC voltage at the connection points of the multiple bridge arms, and the power factor angle.

[0030] Optionally, after calculating the arm current of each arm based on the system parameters, the method further includes:

[0031] When the maximum value of the bridge arm current in any bridge arm is greater than the maximum utilization current of the IGBT in the bridge arm reuse DC transformer, the AC voltage amplitude of the multiple bridge arm connection points is reacquired.

[0032] Based on the same inventive concept, the present invention also provides a submodule type determination system for a bridge arm multiplexed DC transformer, the system comprising:

[0033] The parameter acquisition unit is used to acquire the system parameters of the bridge arm multiplexed DC transformer, the DC voltage of multiple bridge arms in the bridge arm multiplexed DC transformer, and the AC voltage amplitude of multiple bridge arm connection points;

[0034] The arm current calculation unit is used to calculate the arm current of each arm based on the system parameters.

[0035] The submodule type determination unit is used to determine the submodule type of each bridge arm in the bridge arm multiplexed DC transformer based on the bridge arm current and DC voltage of each bridge arm and the AC voltage amplitude, when the maximum value of the bridge arm current of each bridge arm is less than or equal to the maximum utilization current of the IGBT in the bridge arm multiplexed DC transformer.

[0036] Optionally, the submodule type determination unit includes:

[0037] The voltage difference determination module is used to calculate the difference between the DC voltage and the AC voltage amplitude of each bridge arm to obtain the voltage difference of each bridge arm.

[0038] The submodule type determination module is used to determine the submodule type of each bridge arm in the bridge arm multiplexed DC transformer based on the voltage difference and bridge arm current of each bridge arm.

[0039] Optionally, the submodule type determination module is specifically used for:

[0040] When the voltage difference is greater than or equal to zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm sub-module type of the bridge arm in the bridge arm multiplexed DC transformer is determined to be a full bridge type; if the minimum value of the bridge arm current is less than zero, the bridge arm sub-module type of the bridge arm in the bridge arm multiplexed DC transformer is determined to be a half bridge type.

[0041] When the voltage difference is less than zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a full-bridge type; if the current difference is less than zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a hybrid type.

[0042] Optionally, the submodule type determination module is specifically used for:

[0043] Based on the DC voltage of the bridge arm, the AC voltage amplitude, and the rated voltage of the bridge arm submodule, the number of full-bridge submodules in the hybrid type is calculated.

[0044] Optionally, the calculation method for the number of full-bridge sub-modules in the hybrid type satisfies the following inequality:

[0045]

[0046] Where, N 全 U represents the number of full-bridge submodules in the hybrid configuration. ac U represents the amplitude of AC voltage. dc U represents the DC voltage of the bridge arm. capN This represents the rated voltage of the bridge arm submodule, and this represents the rounding function, which rounds up.

[0047] Optionally, the system parameters include high-voltage port voltage, low-voltage port voltage, transmission capacity, number of phases, and number of poles;

[0048] The bridge arm current calculation unit includes:

[0049] The current component determination module is used to calculate the DC current component and AC current component of each bridge arm based on the high voltage port voltage, the low voltage port voltage, the transmission capacity, the number of phases, and the number of poles.

[0050] The arm current determination module is used to superimpose the DC current component and AC current component of each arm to obtain the arm current of each arm.

[0051] Optionally, the plurality of bridge arms are high-voltage bridge arms, multiplex bridge arms, and low-voltage bridge arms;

[0052] The current component determination module is specifically used for:

[0053] Based on the high-voltage port voltage, the transmission capacity, the number of phases, and the number of poles, the DC current component of the high-voltage bridge arm is calculated;

[0054] Based on the effective value of AC voltage, power factor angle, voltage of the high-voltage port, voltage of the low-voltage port, and DC current component of the high-voltage bridge arm at multiple bridge arm connection points, the AC current component of the high-voltage bridge arm is calculated using the energy balance principle of the high-voltage bridge arm.

[0055] Based on the low-voltage port voltage, the transmission capacity, the number of phases, the number of poles, and the number of low-voltage ports, the DC current component of the low-voltage bridge arm is calculated.

[0056] Based on the DC current component of the low-voltage bridge arm, the AC current component of the low-voltage bridge arm is determined using the energy balance principle of the low-voltage bridge arm.

[0057] The DC current component of the multiplexed bridge arm is calculated based on the DC current component of the high-voltage bridge arm, the DC current component of the low-voltage bridge arm, and the number of low-voltage ports.

[0058] The AC current component of the multiplexed bridge arm is calculated based on the low-voltage port voltage, the DC current component of the multiplexed bridge arm, the effective value of the AC voltage at the connection points of the multiple bridge arms, and the power factor angle.

[0059] Optionally, the system further includes:

[0060] An AC voltage amplitude update unit is used to update the AC voltage amplitude at the multiple bridge arm connection points when the maximum value of the bridge arm current in any bridge arm is greater than the maximum utilization current of the IGBT in the bridge arm multiplexed DC transformer.

[0061] Based on the same inventive concept, the present invention also provides a computing device, comprising: one or more processors;

[0062] A processor is used to execute one or more programs;

[0063] When the one or more programs are executed by the one or more processors, a method for determining the submodule type of a bridge arm multiplexed DC transformer as described above is implemented.

[0064] Based on the same inventive concept, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, it implements the method for determining the sub-module type of a bridge arm multiplexed DC transformer as described above.

[0065] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0066] This invention provides a method and system for determining the submodule type of a bridge arm reuse type DC transformer. This submodule type determination method effectively obtains the bridge arm current of each bridge arm through the system parameters of the bridge arm reuse type DC transformer. When the maximum value of the bridge arm current in each bridge arm is less than or equal to the maximum utilization current of the IGBT in the bridge arm reuse type DC transformer, the submodule type of each bridge arm in the bridge arm reuse type DC transformer is determined based on the bridge arm current, DC voltage, and AC voltage amplitude. This allows for determining the configuration of each bridge arm submodule of the bridge arm reuse type DC transformer under different operating conditions, while reducing the equipment cost of the DC transformer and ensuring good economic benefits. Furthermore, when the maximum value of the bridge arm current in any bridge arm is greater than the maximum utilization current of the IGBT, by increasing the AC voltage amplitude, the submodule type of the reused bridge arm becomes a hybrid type, improving the high-capacity power transmission capability of the DC transformer under high transformation ratio conditions. Attached Figure Description

[0067] Figure 1 A flowchart illustrating a method for determining the submodule type of a bridge arm multiplexed DC transformer provided by the present invention;

[0068] Figure 2 A schematic diagram of the phase unit topology of a bridge arm multiplexed DC transformer provided by the present invention;

[0069] Figure 3 A flowchart of another method for determining the submodule type of a bridge arm multiplexed DC transformer provided by the present invention;

[0070] Figure 4 This invention provides a schematic diagram of a phase unit topology suitable for a high-capacity, high-ratio bridge arm reuse type DC transformer.

[0071] Figure 5 A flowchart illustrating a method for determining the submodule type of another bridge arm reuse type DC transformer provided by the present invention;

[0072] Figure 6 A flowchart for determining the type of a bridge arm multiplexed DC transformer submodule provided by the present invention;

[0073] Figure 7 A block diagram of a submodule type determination system for a bridge arm multiplexed DC transformer provided by the present invention;

[0074] Figure 8 A computer device provided by the present invention. Detailed Implementation

[0075] Example 1:

[0076] Figure 1 A flowchart illustrating a method for determining the submodule type of a bridge arm multiplexed DC transformer provided by this invention is shown below. Figure 1 As shown, the method may include the following steps:

[0077] In step 101, the system parameters of the bridge arm multiplexing DC transformer, the DC voltage of multiple bridge arms in the bridge arm multiplexing DC transformer, and the AC voltage amplitude of multiple bridge arm connection points are obtained.

[0078] The system parameters may include high-voltage port voltage, low-voltage port voltage, transmission capacity, number of phases and number of poles. The multiple arms in a bridge arm reuse type DC transformer can be high-voltage arms, reused arms and low-voltage arms.

[0079] It should be noted that the system parameters of the bridge arm multiplexing DC transformer, the DC voltage of multiple bridge arms in the bridge arm multiplexing DC transformer, and the AC voltage amplitude of multiple bridge arm connection points can be obtained through a preset interface. Multiple bridge arm connection points can also be referred to as common points.

[0080] In step 102, the bridge arm current of each bridge arm is calculated based on the system parameters.

[0081] The bridge arm current can include both DC current and AC current components.

[0082] In step 103, when the maximum value of the bridge arm current in each bridge arm is less than or equal to the maximum utilization current of the IGBT (Insulated Gate Bipolar Transistor) in the bridge arm multiplexed DC transformer, the bridge arm submodule type of each bridge arm in the bridge arm multiplexed DC transformer is determined based on the bridge arm current and DC voltage of each bridge arm and the AC voltage amplitude.

[0083] For example, since the utilization rate of IGBT devices should not be too high, the current of each bridge arm should not exceed 75% of the rated current of the IGBT:

[0084] I H I W I L ≤75%I IGBT

[0085] Among them, I H I represents the maximum value of the high-voltage bridge arm current. W To reuse the maximum value of the bridge arm current, I L The maximum value of the low-voltage bridge arm current is obtained by superimposing the DC current component with the AC current component.

[0086] The maximum value I of the high-voltage bridge arm current H Satisfy the following formula:

[0087]

[0088] Among them, I ac_H I represents the DC current component of the high-voltage bridge arm. dc_H This represents the DC current component of the high-voltage bridge arm.

[0089] Maximum value I of the multiplexed bridge arm current W Satisfy the following formula:

[0090] I L =I dc_L

[0091] Among them, I dc_L This represents the DC current component of the low-voltage bridge arm.

[0092] The maximum value of the low-voltage bridge arm current I L Satisfy the following formula:

[0093]

[0094] Among them, I ac_W I represents the AC current component of the multiplexed bridge arm. dc_W This represents the DC current component of the multiplexed bridge arm.

[0095] This invention proposes a method for determining the sub-module type of a bridge arm multiplexed DC transformer, which improves the utilization rate of components and enhances the economic benefits of DC equipment.

[0096] The bridge arm reuse type DC transformer has become the mainstream topology due to its excellent characteristics such as not requiring an intermediate frequency isolation transformer, requiring fewer sub-modules, and strong engineering applicability. However, there is currently a lack of systematic methods for determining the form of each bridge arm sub-module in this topology. In particular, under high transformation ratio conditions, due to the limitation of the low voltage port voltage level, there is an urgent need to propose a method for configuring the form of each bridge arm sub-module of the bridge arm reuse type DC transformer that can meet the requirements of large-capacity transmission while ensuring economic benefits.

[0097] To address existing problems, this invention proposes a method for determining the sub-module type of a bridge arm reuse type DC transformer. This method can determine the configuration type of each bridge arm sub-module of the bridge arm reuse type DC transformer under different operating conditions, while improving the utilization rate of IGBT devices and ensuring good economic benefits.

[0098] For example, the present invention aims to provide a parameter design method for a high-capacity, high-ratio bridge arm reused DC transformer. By increasing the AC voltage amplitude and using a hybrid full- and half-bridge submodule for the reused bridge arm, the high-capacity power transmission capability of the DC transformer under high-ratio operating conditions is improved.

[0099] Basic topology of bridge arm multiplexed DC transformer as follows Figure 2 As shown:

[0100] This topology comprises three arms: a high-voltage arm, a multiplexed arm, and a low-voltage arm. The connection point of these three arms is a common point. To meet economic requirements, the DC voltage component of the low-voltage arm is set to zero, the DC voltage component of the multiplexed arm is equal to the DC voltage at the low-voltage port, and the amplitude of the AC voltage at the common point must be lower than that of the DC voltage component of the multiplexed arm. Under low transformer ratio conditions (ratio not greater than 3), the amplitude of the AC voltage at the common point is generally controlled at 60% to 80% of the DC voltage component of the multiplexed arm. The high-voltage arm and the multiplexed arm require a half-bridge submodule (HBSM), while the low-voltage arm requires a full-bridge submodule (FBSM).

[0101] Figure 3 A flowchart illustrating another method for determining the submodule type of a bridge arm multiplexed DC transformer provided by the present invention is shown below. Figure 3 As shown above, Figure 1 A specific implementation of step 103 shown may include the following steps:

[0102] In step 1031, the difference between the DC voltage and the AC voltage amplitude of each bridge arm is calculated to obtain the voltage difference value of each bridge arm.

[0103] In step 1032, the bridge arm submodule type of each bridge arm in the bridge arm multiplexed DC transformer is determined based on the voltage difference and bridge arm current of each bridge arm.

[0104] Possible implementation methods in this step include: when the voltage difference is greater than or equal to zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a full-bridge type; if the minimum value of the bridge arm current is less than zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a half-bridge type; when the voltage difference is less than zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a full-bridge type; if the current difference is less than zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a hybrid type.

[0105] For example, in a bridge arm multiplexed DC transformer, the low-voltage port voltage U L The relatively small current results in excessively large AC current components in the high-voltage bridge arm and the multiplexed bridge arm, as well as excessively large DC current components in the low-voltage bridge arm. The total current of each bridge arm far exceeds the maximum utilization rate of the IGBT device, making it difficult to meet the design requirements.

[0106] To address the aforementioned issues, a method for determining the submodule type of a bridge-arm multiplexed DC transformer is proposed, as detailed below. Figure 4 As shown:

[0107] By increasing the AC voltage amplitude at the common point, the AC current component of the high-voltage arm and the reused arm can be significantly reduced. Since the AC voltage amplitude is greater than the DC voltage component of the reused arm at this time, the voltage of the reused arm will be less than zero. Based on the magnitude of the arm current, there are four possible operating conditions for the arm. Submodule configuration methods are proposed for each of the four operating conditions.

[0108] When the AC voltage amplitude U ac Less than the DC voltage U of the bridge arm dc At this time, the bridge arm voltage output is positive, and the bridge arm current is at its minimum value (i.e., I). dc -I ac When the current crosses zero, the bridge arm is equipped with a half-bridge sub-module; when the minimum current of the bridge arm does not cross zero, the bridge arm is equipped with a full-bridge sub-module.

[0109] When the AC voltage amplitude U ac Greater than the DC voltage U of the bridge arm dc At this time, the bridge arm voltage output is negative, and the bridge arm current is at its minimum value (i.e., I). dc-I ac However, when the minimum current of the bridge arm crosses zero, a full-bridge sub-module is required; when the minimum current of the bridge arm crosses zero, a hybrid full-bridge and half-bridge sub-module is required.

[0110] For example, consider a ±200kV / ±50kV bridge arm reused DC transformer transmitting a 200MW capacity.

[0111] When the AC voltage amplitude at the common point is selected as 30kV, the configuration of each bridge arm submodule of the transformer is as follows: High voltage / common (i.e., reused) / Low voltage: half bridge / half bridge / full bridge;

[0112] When the AC voltage amplitude at the common point is selected as 60kV, the configuration of each bridge arm submodule of the transformer is as follows: High voltage / common (i.e., reused) / Low voltage: half bridge / half bridge hybrid / full bridge;

[0113] When the AC voltage amplitude at the common point is selected as 80kV, the configuration of each bridge arm submodule of the transformer is as follows: High voltage / common (i.e., reused) / low voltage: half bridge / full bridge / full bridge.

[0114] Optionally, after determining that the bridge arm submodule type of the bridge arm in the bridge arm multiplexed DC transformer is a hybrid type, the method further includes:

[0115] Based on the DC voltage of the bridge arm, the AC voltage amplitude, and the rated voltage of the bridge arm submodule, the number of full-bridge submodules in the hybrid type is calculated.

[0116] It should be noted that the minimum number of full-bridge submodules in the hybrid full-and-half-bridge configuration is calculated by dividing the difference between the peak AC voltage and the DC voltage by the submodule's rated voltage, rounded up. This minimum number of full-bridge submodules in the hybrid configuration is calculated using the DC voltage and AC voltage amplitude of the bridge arm and the rated voltage of the bridge arm submodules. This avoids increasing equipment costs due to full-bridge submodules, thereby improving economic efficiency. The calculation method for the number of full-bridge submodules in the hybrid configuration satisfies the following inequality:

[0117]

[0118] Where, N 全 U represents the number of full-bridge submodules in the hybrid configuration. ac U represents the amplitude of AC voltage. dc U represents the DC voltage of the bridge arm. capN This represents the rated voltage of the bridge arm submodule, and this represents the rounding function, which rounds up.

[0119] To meet the requirements of larger transmission capacity, the AC voltage amplitude needs to be increased to exceed the DC voltage amplitude of the bridge arm. Compared with traditional design schemes, replacing components with larger current ratings would significantly increase equipment costs and result in lower economic efficiency. The bridge arm submodule configuration proposed in this application offers good economic benefits and can enable the bridge arm reuse-type DC transformer to complete large-capacity power transmission under high transformation ratio conditions.

[0120] Figure 5 A flowchart illustrating another method for determining the submodule type of a bridge arm multiplexed DC transformer provided by the present invention, wherein when the system parameters include high-voltage port voltage, low-voltage port voltage, transmission capacity, number of phases, and number of poles, such as... Figure 5 As shown above, Figure 1 A specific implementation of step 102 shown may include the following steps:

[0121] In step 1021, the DC current component and AC current component of each bridge arm are calculated based on the high voltage port voltage, the low voltage port voltage, the transmission capacity, the number of phases, and the number of poles.

[0122] In step 1022, the DC current component and AC current component of each bridge arm are superimposed to obtain the bridge arm current of each bridge arm.

[0123] It should be noted that when the multiple bridge arms are high-voltage bridge arms, reused bridge arms, and low-voltage bridge arms, the above... Figure 5 Possible implementations of step 1021 shown may include the following steps:

[0124] In step 501, the DC current component of the high-voltage bridge arm is calculated based on the high-voltage port voltage, the transmission capacity, the number of phases, and the number of poles.

[0125] It should be noted that the calculation method for the DC current component of the high-voltage bridge arm satisfies the following formula:

[0126] I dc_H =P / (N×M×U) H )

[0127] Among them, I dc_H This represents the DC current component of the high-voltage bridge arm, where N represents the number of phases, M represents the number of poles, and U... H This indicates the high-voltage port voltage, and P represents the transmission capacity of the DC transformer.

[0128] In step 502, based on the effective value of AC voltage, power factor angle, voltage of the high-voltage port, voltage of the low-voltage port, and DC current component of the high-voltage bridge arm at multiple bridge arm connection points, the AC current component of the high-voltage bridge arm is calculated using the high-voltage bridge arm energy balance principle.

[0129] It should be noted that the calculation method for the AC current component of the high-voltage bridge arm satisfies the following formula:

[0130] I ac_H =(U H -U L )I dc_H / U ac_rms cosφ

[0131] Among them, I ac_H U represents the DC current component of the high-voltage bridge arm. H U represents the high-voltage port voltage. L Indicates the low-voltage port voltage, I dc_H U represents the DC current component of the high-voltage bridge arm. ac_rms This represents the effective value of the AC voltage at multiple bridge arm connection points, and φ represents the power factor angle.

[0132] In step 503, the DC current component of the low-voltage bridge arm is calculated based on the low-voltage port voltage, the transmission capacity, the number of phases, the number of poles, and the number of low-voltage ports.

[0133] It should be noted that the calculation method for the DC current component of the low-voltage bridge arm satisfies the following formula:

[0134] I dc_L =P / (N×M×U) L ×n)

[0135] Among them, I dc_L This represents the DC current component of the low-voltage bridge arm, where N represents the number of phases, M represents the number of poles, and U... L The value represents the low-voltage port voltage, P represents the transmission capacity of the DC transformer, and n represents the number of low-voltage ports.

[0136] In step 504, the AC current component of the low-voltage bridge arm is determined based on the DC current component of the low-voltage bridge arm using the low-voltage bridge arm energy balance principle.

[0137] It should be noted that, by setting the DC voltage component of the low-voltage bridge arm to 0, and using the energy balance principle of the low-voltage bridge arm, we can determine that the AC power of the low-voltage bridge arm is 0. Therefore, we can also determine that the AC current component of the low-voltage bridge arm is 0, i.e., I... ac_L =0, where I ac_L This represents the AC current component of the low-voltage bridge arm.

[0138] In step 505, the DC current component of the multiplexed bridge arm is calculated based on the DC current component of the high-voltage bridge arm, the DC current component of the low-voltage bridge arm, and the number of low-voltage ports.

[0139] It should be noted that the calculation method for the DC current component of the multiplexed bridge arm satisfies the following formula:

[0140] I dc_W =I dc_H -I dc_L ×n

[0141] Among them, I dc_W I represents the DC current component of the multiplexed bridge arm. dc_H I represents the DC current component of the high-voltage bridge arm. dc_L This represents the DC current component of the low-voltage bridge arm, and n represents the number of low-voltage ports.

[0142] In step 506, the AC current component of the multiplexed bridge arm is calculated based on the low-voltage port voltage, the DC current component of the multiplexed bridge arm, the effective value of the AC voltage at the connection points of the multiple bridge arms, and the power factor angle.

[0143] It should be noted that the calculation method for the AC current component of the multiplexed bridge arm satisfies the following formula:

[0144] I ac_W =U L I dc_W / U ac_rms cosφ

[0145] Among them, I ac_W U represents the AC current component of the multiplexed bridge arm. L Indicates the low-voltage port voltage, I dc_W U represents the DC current component of the multiplexed bridge arm. ac_rms This represents the effective value of the AC voltage at multiple bridge arm connection points, and φ represents the power factor angle.

[0146] Optionally, after calculating the arm current of each arm based on the system parameters, the method further includes:

[0147] When the maximum value of the bridge arm current in any bridge arm is greater than the maximum utilization current of the IGBT in the bridge arm reuse DC transformer, the AC voltage amplitude of the multiple bridge arm connection points is reacquired.

[0148] It should be noted that by re-acquiring the AC voltage amplitude at multiple bridge arm connection points, increasing the peak AC voltage at the common point, and reducing the current in each bridge arm, the maximum utilization limit of the IGBT can be met while also allowing the selection of devices with lower current ratings. This enables the DC transformer to have a large transmission capacity under various operating conditions, while ensuring good economic benefits.

[0149] For example, Figure 6 The flowchart for determining the type of the bridge arm multiplexed DC transformer submodule provided by this invention will be described below in conjunction with...Figure 6 The specific implementation schemes of the present invention are described in detail below:

[0150] Step S1: Input system parameters.

[0151] It should be noted that before confirming the type of the bridge arm reuse type DC transformer submodule, the system parameters of the DC transformer (i.e., system parameters) need to be entered. The system parameters include port voltage (including high voltage port voltage and low voltage port voltage), transmission capacity, number of phases and number of poles.

[0152] Step S2: Determine the AC voltage amplitude at the common point S.

[0153] Among them, the common point can be multiple bridge arm connection points.

[0154] Step S3: Calculate the current of each bridge arm using the system parameters of the DC transformer and the amplitude of the AC voltage at the common point. Determine whether the current of each bridge arm is less than the maximum utilization current of the IGBT device. If it is greater than the maximum utilization current of the IGBT device, increase the amplitude of the AC voltage at the common point until the current of each bridge arm is less than the maximum utilization current of the IGBT device. If the current of each bridge arm is less than the maximum utilization current of the IGBT device, proceed to step S4.

[0155] One method is to increase the AC voltage amplitude at the common point by re-receiving the AC voltage amplitude at the common point through a preset interface, so that the current in each bridge arm is less than the maximum utilization current of the IGBT device.

[0156] Step S4: Determine the relationship between the AC voltage amplitude at the common point and the DC voltage of each bridge arm (i.e., U). dc -U ac >0?) and the sign of the bridge arm current (i.e., I dc -I ac >0?), if the AC voltage amplitude is less than the DC voltage of the bridge arm (U dc -U ac >0) and the minimum value of the bridge arm current is not zero (I dc -I ac If the AC voltage amplitude is less than 0, then the bridge arm is equipped with a full-bridge module; if the AC voltage amplitude is less than the DC voltage of the bridge arm (U dc -U ac >0<0) and the minimum value of the bridge arm current crosses zero (I dc -I ac If the AC voltage amplitude is greater than the DC voltage of the bridge arm (U), then the bridge arm is equipped with a half-bridge module; if the AC voltage amplitude is greater than the DC voltage of the bridge arm (U), then the bridge arm is equipped with a half-bridge module. dc -U ac <0) and the minimum value of the bridge arm current does not exceed zero (I dc -I ac If the AC voltage amplitude is greater than the DC voltage of the bridge arm (U<0), then the bridge arm is equipped with a full-bridge module; if the AC voltage amplitude is greater than the DC voltage of the bridge arm (U0), then the bridge arm is equipped with a full-bridge module. dc -Uac <0) and the minimum value of the bridge arm current crosses zero (I dc -I ac If the value is greater than 0), then the bridge arm is equipped with a hybrid full-bridge / half-bridge module.

[0157] The present invention aims to provide a method for determining the type of each arm submodule of a bridge arm multiplexed DC transformer, so as to ensure that the DC transformer can have a large transmission capacity under various operating conditions, while also having good economic benefits.

[0158] Example 2:

[0159] Figure 7 A block diagram of a submodule type determination system for a bridge arm multiplexed DC transformer provided by the present invention is shown below. Figure 7 As shown, the system includes:

[0160] The parameter acquisition unit 701 is used to acquire the system parameters of the bridge arm multiplex DC transformer, the DC voltage of multiple bridge arms in the bridge arm multiplex DC transformer, and the AC voltage amplitude of multiple bridge arm connection points;

[0161] The bridge arm current calculation unit 702 is used to calculate the bridge arm current of each bridge arm based on the system parameters.

[0162] The submodule type determination unit 703 is used to determine the submodule type of each bridge arm in the bridge arm multiplexed DC transformer based on the bridge arm current and DC voltage of each bridge arm and the AC voltage amplitude, when the maximum value of the bridge arm current of each bridge arm is less than or equal to the maximum utilization current of the IGBT in the bridge arm multiplexed DC transformer.

[0163] Optionally, the submodule type determination unit 703 includes:

[0164] The voltage difference determination module is used to calculate the difference between the DC voltage and the AC voltage amplitude of each bridge arm to obtain the voltage difference of each bridge arm.

[0165] The submodule type determination module is used to determine the submodule type of each bridge arm in the bridge arm multiplexed DC transformer based on the voltage difference and bridge arm current of each bridge arm.

[0166] Optionally, the submodule type determination module is specifically used for:

[0167] When the voltage difference is greater than or equal to zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm sub-module type of the bridge arm in the bridge arm multiplexed DC transformer is determined to be a full bridge type; if the minimum value of the bridge arm current is less than zero, the bridge arm sub-module type of the bridge arm in the bridge arm multiplexed DC transformer is determined to be a half bridge type.

[0168] When the voltage difference is less than zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a full-bridge type; if the current difference is less than zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a hybrid type.

[0169] Optionally, the submodule type determination module is specifically used for:

[0170] Based on the DC voltage of the bridge arm, the AC voltage amplitude, and the rated voltage of the bridge arm submodule, the number of full-bridge submodules in the hybrid type is calculated.

[0171] Optionally, the calculation method for the number of full-bridge sub-modules in the hybrid type satisfies the following inequality:

[0172]

[0173] Where, N 全 U represents the number of full-bridge submodules in the hybrid configuration. ac U represents the amplitude of AC voltage. dc U represents the DC voltage of the bridge arm. capN This represents the rated voltage of the bridge arm submodule, and this represents the rounding function, which rounds up.

[0174] Optionally, the system parameters include high-voltage port voltage, low-voltage port voltage, transmission capacity, number of phases, and number of poles;

[0175] The bridge arm current calculation unit 702 includes:

[0176] The current component determination module is used to calculate the DC current component and AC current component of each bridge arm based on the high voltage port voltage, the low voltage port voltage, the transmission capacity, the number of phases, and the number of poles.

[0177] The arm current determination module is used to superimpose the DC current component and AC current component of each arm to obtain the arm current of each arm.

[0178] Optionally, the plurality of bridge arms are high-voltage bridge arms, multiplex bridge arms, and low-voltage bridge arms;

[0179] The current component determination module is specifically used for:

[0180] Based on the high-voltage port voltage, the transmission capacity, the number of phases, and the number of poles, the DC current component of the high-voltage bridge arm is calculated;

[0181] Based on the effective value of AC voltage, power factor angle, voltage of the high-voltage port, voltage of the low-voltage port, and DC current component of the high-voltage bridge arm at multiple bridge arm connection points, the AC current component of the high-voltage bridge arm is calculated using the energy balance principle of the high-voltage bridge arm.

[0182] Based on the low-voltage port voltage, the transmission capacity, the number of phases, the number of poles, and the number of low-voltage ports, the DC current component of the low-voltage bridge arm is calculated.

[0183] Based on the DC current component of the low-voltage bridge arm, the AC current component of the low-voltage bridge arm is determined using the energy balance principle of the low-voltage bridge arm.

[0184] The DC current component of the multiplexed bridge arm is calculated based on the DC current component of the high-voltage bridge arm, the DC current component of the low-voltage bridge arm, and the number of low-voltage ports.

[0185] The AC current component of the multiplexed bridge arm is calculated based on the low-voltage port voltage, the DC current component of the multiplexed bridge arm, the effective value of the AC voltage at the connection points of the multiple bridge arms, and the power factor angle.

[0186] Optionally, the system further includes:

[0187] An AC voltage amplitude update unit is used to re-acquire the AC voltage amplitude of the multiple bridge arm connection points when the maximum value of the bridge arm current in any bridge arm is greater than the maximum utilization current of the IGBT in the bridge arm multiplexed DC transformer.

[0188] Example 3:

[0189] Based on the same inventive concept, the present invention also provides a computer device, such as... Figure 8 As shown, the computer device includes a processor and a memory. The memory stores a computer program, which includes program instructions. The processor executes the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), or application-specific integrated circuits (ASICs).

[0190] Application Specific Integrated Circuit (ASIC), Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., are the computing core and control core of the terminal. They are suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to realize the corresponding method flow or corresponding function, so as to realize the steps of the sub-module type determination method of a bridge arm multiplexed DC transformer in the above embodiments.

[0191] Example 4:

[0192] Based on the same inventive concept, this invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device used to store programs and data. It is understood that the computer-readable storage medium here can include both the built-in storage medium in the computer device and extended storage media supported by the computer device. The computer-readable storage medium provides storage space that stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more computer programs (including program code). It should be noted that the computer-readable storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the submodule type determination method for a bridge arm multiplexed DC transformer in the above embodiments.

[0193] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0194] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0195] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0196] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0197] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A method for determining the submodule type of a bridge arm multiplexed DC transformer, characterized in that, The method includes: Obtain the system parameters of the bridge arm multiplexed DC transformer, the DC voltage of multiple bridge arms in the bridge arm multiplexed DC transformer, and the AC voltage amplitude of multiple bridge arm connection points; Based on the system parameters, the bridge arm current of each bridge arm is calculated; When the maximum value of the bridge arm current in each bridge arm is less than or equal to the maximum utilization current of the IGBT in the bridge arm reuse DC transformer, the bridge arm submodule type of each bridge arm in the bridge arm reuse DC transformer is determined based on the bridge arm current and DC voltage of each bridge arm and the AC voltage amplitude.

2. The method according to claim 1, characterized in that, The determination of the bridge arm submodule type for each bridge arm in the bridge arm multiplexed DC transformer, based on the bridge arm current and DC voltage of each bridge arm and the AC voltage amplitude, includes: The difference between the DC voltage and the AC voltage amplitude of each bridge arm is calculated to obtain the voltage difference value of each bridge arm; Based on the voltage difference and current of each bridge arm, the bridge arm submodule type of each bridge arm in the bridge arm multiplexed DC transformer is determined.

3. The method according to claim 2, characterized in that, The process of determining the bridge arm submodule type of each bridge arm in the bridge arm multiplexed DC transformer based on the voltage difference and bridge arm current of each bridge arm includes: When the voltage difference is greater than or equal to zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm sub-module type of the bridge arm in the bridge arm multiplexed DC transformer is determined to be a full bridge type; if the minimum value of the bridge arm current is less than zero, the bridge arm sub-module type of the bridge arm in the bridge arm multiplexed DC transformer is determined to be a half bridge type. When the voltage difference is less than zero, if the minimum value of the bridge arm current is greater than or equal to zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a full-bridge type; if the current difference is less than zero, the bridge arm submodule type of the bridge arm in the bridge arm reuse DC transformer is determined to be a hybrid type.

4. The method according to claim 3, characterized in that, After determining that the bridge arm submodule type in the bridge arm multiplexed DC transformer is a hybrid type, the method further includes: Based on the DC voltage of the bridge arm, the AC voltage amplitude, and the rated voltage of the bridge arm submodule, the number of full-bridge submodules in the hybrid type is calculated.

5. The method according to claim 4, characterized in that, The calculation method for the number of full-bridge sub-modules in the hybrid type satisfies the following inequality: Where, N 全 U represents the number of full-bridge submodules in the hybrid configuration. ac U represents the amplitude of AC voltage. dc U represents the DC voltage of the bridge arm. capN Indicates the rated voltage of the bridge arm submodule. This represents the floor function, which rounds up.

6. The method according to any one of claims 1-5, characterized in that, The system parameters include high-voltage port voltage, low-voltage port voltage, transmission capacity, number of phases, and number of poles; The calculation of the bridge arm current for each bridge arm based on the system parameters includes: Based on the high-voltage port voltage, the low-voltage port voltage, the transmission capacity, the number of phases, and the number of poles, the DC current component and AC current component of each bridge arm are calculated. The DC current component and AC current component of each bridge arm are superimposed to obtain the bridge arm current of each bridge arm.

7. The method according to claim 6, characterized in that, The multiple bridge arms are high-voltage bridge arms, reused bridge arms, and low-voltage bridge arms; The calculation of the DC current component and AC current component of each bridge arm based on the high-voltage port voltage, the low-voltage port voltage, the transmission capacity, the number of phases, and the number of poles includes: Based on the high-voltage port voltage, the transmission capacity, the number of phases, and the number of poles, the DC current component of the high-voltage bridge arm is calculated; Based on the effective value of AC voltage, power factor angle, voltage of the high-voltage port, voltage of the low-voltage port, and DC current component of the high-voltage bridge arm at multiple bridge arm connection points, the AC current component of the high-voltage bridge arm is calculated using the energy balance principle of the high-voltage bridge arm. Based on the low-voltage port voltage, the transmission capacity, the number of phases, the number of poles, and the number of low-voltage ports, the DC current component of the low-voltage bridge arm is calculated. Based on the DC current component of the low-voltage bridge arm, the AC current component of the low-voltage bridge arm is determined using the energy balance principle of the low-voltage bridge arm. The DC current component of the multiplexed bridge arm is calculated based on the DC current component of the high-voltage bridge arm, the DC current component of the low-voltage bridge arm, and the number of low-voltage ports. The AC current component of the multiplexed bridge arm is calculated based on the low-voltage port voltage, the DC current component of the multiplexed bridge arm, the effective value of the AC voltage at the connection points of the multiple bridge arms, and the power factor angle.

8. The method according to claim 1, characterized in that, After calculating the bridge arm current for each bridge arm based on the system parameters, the method further includes: When the maximum value of the bridge arm current in any bridge arm is greater than the maximum utilization current of the IGBT in the bridge arm reuse DC transformer, the AC voltage amplitude of the multiple bridge arm connection points is reacquired.

9. A submodule type determination system for a bridge arm multiplexed DC transformer, characterized in that, The system includes: The parameter acquisition unit is used to acquire the system parameters of the bridge arm multiplexed DC transformer, the DC voltage of multiple bridge arms in the bridge arm multiplexed DC transformer, and the AC voltage amplitude of multiple bridge arm connection points; The arm current calculation unit is used to calculate the arm current of each arm based on the system parameters. The submodule type determination unit is used to determine the submodule type of each bridge arm in the bridge arm multiplexed DC transformer based on the bridge arm current and DC voltage of each bridge arm and the AC voltage amplitude, when the maximum value of the bridge arm current of each bridge arm is less than or equal to the maximum utilization current of the IGBT in the bridge arm multiplexed DC transformer.

10. A computer device, characterized in that, include: One or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the method for determining the submodule type of the bridge arm multiplexed DC transformer as described in any one of claims 1 to 8 is implemented.

11. A computer-readable storage medium, characterized in that, It contains a computer program, which, when executed, implements the method for determining the submodule type of the bridge arm multiplexed DC transformer as described in any one of claims 1 to 8.

Images