A method, device, equipment and medium for calculating the withstand voltage of a flexible DC transformer

Abstract

The present invention discloses a method, device, equipment and medium for calculating the withstand voltage of a flexible DC transformer. In response to received user request information, the method determines the symmetrical monopole flexible DC transmission system corresponding to the user request information and obtains corresponding target input parameters and voltage model construction parameters. The voltage model construction parameters are used to construct an instantaneous voltage model. The target input parameters are used to input the instantaneous voltage model to generate corresponding insulation withstand voltage data. According to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, a preset margin coefficient key-value pair database is retrieved, the target margin coefficient corresponding to the insulation withstand voltage data is matched, and the target withstand voltage is calculated using the insulation withstand voltage data and the target margin coefficient. The method solves the technical problems of the existing method, such as the complex modeling structure, the need to model the entire DC system in order to consider the insulation level of the connecting transformer equipment, the large workload of working condition scanning, the slow calculation speed and the low efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible DC transformers, and in particular to a method, device, equipment and medium for calculating the withstand voltage of a flexible DC transformer. Background Art

[0002] Flexible DC transmission is a new transmission technology based on voltage source converters, self-shutoff devices and pulse width modulation technology. Compared with traditional DC transmission technology, Flexible DC transmission technology does not have the problem of commutation failure, can independently adjust active power and reactive power, and has low harmonic levels.

[0003] There are two practical topologies for flexible DC transmission projects: a symmetrical unipolar system connection and a symmetrical bipolar system. A flexible DC transformer connects the AC grid to the flexible DC converter valve, providing voltage level conversion, isolating AC / DC faults, and limiting short-circuit current. It can be categorized by type as either three-phase or single-phase. The air clearance requirements between the grid-side and valve-side outgoing wires of the flexible DC transformer directly impact the design of the flexible DC transformer's bushings and the overall transformer structure. The calculation of this air clearance must be based on the insulation requirements for the grid-side and valve-side outgoing wires. However, existing air clearance calculation methods lack the ability to select the insulation requirements for the grid-side and valve-side windings of the flexible DC transformer. When designing the flexible DC transformer structure, transformer suppliers often rely on experience, which can lead to the flexible DC transformer structure not meeting the insulation requirements for the grid-side and valve-side outgoing wires in actual projects.

[0004] Because there is no significant overvoltage between the grid-side and valve-side outgoing conductors in traditional AC systems, existing standards for transformer equipment insulation requirements only provide reference values ​​for the insulation levels of outgoing conductors at each voltage level to ground and between phases, lacking insulation requirements across voltage levels. However, in symmetrical single-pole flexible DC projects, the valve-side neutral point is subject to DC voltage bias during a DC single-pole fault, resulting in significant overvoltage between the grid-side and valve-side winding outgoing conductors. Therefore, insulation requirements for the grid-side and valve-side winding outgoing conductors are necessary to guide flexible DC transformer design. Considering that the overvoltage characteristics of flexible DC transformers differ significantly from those of AC projects, the current approach is to use simulation software to build an offshore wind power flexible DC transmission system model, simulate various typical overvoltage conditions, read the maximum overvoltage between the grid-side and valve-side outgoing conductors, and calculate the insulation requirements between the grid-side and valve-side outgoing conductors based on this value, taking into account a certain insulation margin. However, this approach suffers from complex modeling structures, the need to model the entire DC system to account for the insulation level of the interconnected transformer equipment, and the heavy workload of operating condition scanning, slow calculation speed, and low efficiency. Summary of the Invention

[0005] The present invention provides a method, device, equipment and medium for calculating the withstand voltage of a flexible DC transformer, which solves the technical problems of existing methods, such as complex modeling structure, the need to model the entire DC system in order to consider the insulation level of the connected transformer equipment, large workload for operating condition scanning, slow calculation speed and low efficiency.

[0006] A first aspect of the present invention provides a method for calculating the withstand voltage of a flexible DC transformer, comprising:

[0007] In response to the received user request information, determining the symmetrical monopole flexible direct current transmission system corresponding to the user request information and obtaining corresponding target input parameters and voltage model construction parameters;

[0008] constructing a transient voltage model using the voltage model construction parameters;

[0009] Using the target input parameters to input the transient voltage model to generate corresponding insulation withstand voltage data;

[0010] Searching a preset margin coefficient key-value pair database according to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, and matching the target margin coefficient corresponding to the insulation withstand voltage data;

[0011] The target withstand voltage is calculated using the insulation withstand voltage data and the target margin coefficient.

[0012] Optionally, the voltage model construction parameters include grid-side rated voltage data, three-phase voltage initial phase angle data, valve-side rated voltage data, angular frequency, and rated pole-to-ground DC voltage data. The step of constructing the transient voltage model using the voltage model construction parameters includes:

[0013] Constructing a target grid-side three-phase transient voltage model using the three-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data;

[0014] Constructing a target valve-side three-phase transient voltage model using the three-phase voltage initial phase angle data, the angular frequency, the rated pole-to-ground DC voltage data, and the valve-side rated voltage data;

[0015] The target grid-side three-phase transient voltage model and the target valve-side three-phase transient voltage model are used to construct a transient voltage model.

[0016] Optionally, the three-phase voltage initial phase angle data includes phase A voltage initial phase angle data, phase B voltage initial phase angle data, and phase C voltage initial phase angle data. The step of constructing a target grid-side three-phase transient voltage model using the three-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data includes:

[0017] Constructing an initial grid-side a-phase voltage transient model using the a-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data;

[0018] Constructing an initial grid-side b-phase voltage transient model using the b-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data;

[0019] Constructing an initial grid-side C-phase voltage transient model using the C-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data;

[0020] The target grid-side three-phase transient voltage model is constructed by using the initial grid-side a-phase transient voltage model, the initial grid-side b-phase transient voltage model, and the initial grid-side c-phase transient voltage model.

[0021] Optionally, the step of constructing a target valve-side three-phase transient voltage model using the three-phase voltage initial phase angle data, the angular frequency, the rated pole-to-ground DC voltage data, and the valve-side rated voltage data includes:

[0022] Constructing an initial valve-side a-phase voltage transient model using the a-phase voltage initial phase angle data, the angular frequency, and the valve-side rated voltage data;

[0023] Constructing a target valve-side a-phase voltage transient model using the initial valve-side a-phase voltage transient model and the rated pole-to-ground DC voltage data;

[0024] Constructing an initial valve-side b-phase voltage transient model using the b-phase voltage initial phase angle data, the angular frequency, and the valve-side rated voltage data;

[0025] Constructing a target valve-side b-phase voltage transient model using the initial valve-side b-phase voltage transient model and the rated pole-to-ground DC voltage data;

[0026] Constructing an initial valve-side C-phase voltage transient model using the C-phase voltage initial phase angle data, the angular frequency, and the valve-side rated voltage data;

[0027] Constructing a target valve-side C-phase voltage transient model using the initial valve-side C-phase voltage transient model and the rated pole-to-ground DC voltage data;

[0028] The target valve side three-phase transient voltage model is constructed by using the target valve side a-phase transient voltage model, the target valve side b-phase transient voltage model and the target valve side c-phase transient voltage model.

[0029] Optionally, the target input parameters include a target grid-side rated voltage, a target valve-side rated voltage, a target rated pole-to-ground DC voltage, and a grid-side arrester lightning impulse protection level voltage; the insulation withstand voltage data include a maximum switching overvoltage between same-phase grid-side valves, a maximum switching overvoltage between phases of grid-side valves, and a maximum lightning impulse voltage between same phases of grid-side valves; and the step of using the target input parameters to input the transient voltage model to generate corresponding insulation withstand voltage data includes:

[0030] The target grid-side rated voltage, the target valve-side rated voltage, and the target rated pole-to-ground DC voltage are input into the transient voltage model to generate a corresponding maximum switching overvoltage between same-phase grid-side valves;

[0031] The target grid-side rated voltage, the target valve-side rated voltage, and the target rated pole-to-ground DC voltage are input into the transient voltage model to generate a corresponding maximum value of an inter-phase grid-side and inter-valve-side switching overvoltage;

[0032] The target valve-side rated voltage and the grid-side arrester lightning impulse protection level voltage are input into the transient voltage model to generate a corresponding maximum value of the grid-side valve-side same-phase lightning impulse voltage.

[0033] Optionally, the target margin coefficient includes an operating impulse insulation margin coefficient and a lightning impulse insulation margin coefficient, and the step of searching a preset margin coefficient key-value pair database according to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system and matching the target margin coefficient corresponding to the insulation withstand voltage data includes:

[0034] Using the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, generating a corresponding composite key;

[0035] The composite key is input into a preset margin coefficient key-value pair database to match the switching impulse insulation margin coefficient and the lightning impulse insulation margin coefficient corresponding to the insulation withstand voltage data.

[0036] Optionally, the target withstand voltage includes an operating impulse insulation withstand voltage between same-phase grid-side valves, an operating impulse insulation withstand voltage between phase grid-side valves, and a lightning impulse insulation withstand voltage between same-phase grid-side valves. The step of calculating the target withstand voltage using the insulation withstand voltage data and the target margin coefficient includes:

[0037] Calculating the product of the maximum switching overvoltage between the valve sides on the same-phase network side and the switching impulse insulation margin coefficient to generate the corresponding switching impulse insulation withstand voltage between the valve sides on the same-phase network side;

[0038] Calculating the product of the maximum switching overvoltage between the phase-to-grid side valve sides and the switching impulse insulation margin coefficient to generate the corresponding switching impulse insulation withstand voltage between the phase-to-grid side valve sides;

[0039] The product of the maximum value of the lightning impulse voltage between the same phases on the grid-side valve side and the lightning impulse insulation margin coefficient is calculated to generate the corresponding lightning impulse insulation withstand voltage between the same phases on the grid-side valve side.

[0040] A second aspect of the present invention provides a device for calculating the withstand voltage of a flexible DC transformer, comprising:

[0041] a response module, configured to, in response to the received user request information, determine the symmetrical monopole flexible direct current transmission system corresponding to the user request information and obtain corresponding target input parameters and voltage model construction parameters;

[0042] A transient voltage model construction module, configured to construct a transient voltage model using the voltage model construction parameters;

[0043] an insulation withstand voltage data acquisition module, configured to input the transient voltage model using the target input parameters to generate corresponding insulation withstand voltage data;

[0044] a target margin coefficient acquisition module, configured to retrieve a preset margin coefficient key-value pair database according to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, and match the target margin coefficient corresponding to the insulation withstand voltage data;

[0045] A target withstand voltage acquisition module is used to calculate a target withstand voltage using the insulation withstand voltage data and the target margin coefficient.

[0046] A third aspect of the present invention provides an electronic device comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method for calculating the withstand voltage of a flexible DC transformer as described in any one of the above items.

[0047] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed, implements the method for calculating the withstand voltage of a flexible DC transformer as described in any one of the above items.

[0048] It can be seen from the above technical solutions that the present invention has the following advantages:

[0049] In response to the received user request information, the symmetrical monopole flexible direct current transmission system corresponding to the user request information is determined and the corresponding target input parameters and voltage model construction parameters are obtained, the voltage model construction parameters are used to construct an instantaneous voltage model, the target input parameters are used to input the instantaneous voltage model, and the corresponding insulation withstand voltage data is generated. According to the equipment type of the flexible direct current transformer in the symmetrical monopole flexible direct current transmission system, a preset margin coefficient key-value pair database is retrieved, the target margin coefficient corresponding to the insulation withstand voltage data is matched, and the target withstand voltage is calculated using the insulation withstand voltage data and the target margin coefficient; the technical problems of the existing method such as the complex modeling structure, the need to model the entire direct current system in order to consider the insulation level of the connecting transformer equipment, the large workload of the working condition scanning, the slow calculation speed and the low efficiency are solved; by establishing a mathematical model of the instantaneous voltage of the overvoltage mechanism between the grid side and the valve side of the flexible direct current transformer in the flexible direct current system, the withstand voltage required by its insulation level can be calculated quickly and accurately. After obtaining the rated voltages on the grid and valve sides of the project's flexible DC transformer, the rated DC voltage, and the lightning impulse protection level parameters of the flexible DC transformer's grid-side winding to ground, the transient voltage model can be used to obtain the maximum operating and lightning overvoltages between the grid and valve sides of the flexible DC transformer, greatly shortening the overvoltage calculation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0051] Figure 1 A flowchart of a method for calculating the withstand voltage of a flexible DC transformer provided in the first embodiment of the present invention;

[0052] Figure 2 A flowchart of a method for calculating the withstand voltage of a flexible DC transformer provided in the second embodiment of the present invention;

[0053] Figure 3 This is a structural block diagram of a device for calculating the withstand voltage of a flexible DC transformer provided in the third embodiment of the present invention. DETAILED DESCRIPTION

[0054] The embodiments of the present invention provide a method, device, equipment and medium for calculating the withstand voltage of a flexible DC transformer, which are used to solve the technical problems of existing methods, such as complex modeling structure, the need to model the entire DC system in order to consider the insulation level of the connected transformer equipment, large workload of operating condition scanning, slow calculation speed and low efficiency.

[0055] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0056] See also Figure 1 , Figure 1 This is a flowchart of a method for calculating the withstand voltage of a flexible DC transformer provided in the first embodiment of the present invention.

[0057] The present invention provides a method for calculating the withstand voltage of a flexible DC transformer, comprising:

[0058] Step 101: In response to received user request information, determine a symmetrical monopole flexible direct current transmission system corresponding to the user request information and obtain corresponding target input parameters and voltage model building parameters.

[0059] The user request information refers to a calculation request for the withstand voltage of the flexible DC transformer sent by the user.

[0060] A symmetrical monopole flexible direct current transmission system refers to a power grid system consisting of a wind farm / boost station, a flexible direct current transformer, a converter valve, a direct current cable and an onshore alternating current grid.

[0061] The target input parameters refer to the target grid-side rated voltage, target valve-side rated voltage, target rated pole-to-ground DC voltage, and grid-side arrester lightning impulse protection level voltage of the symmetrical monopole flexible DC transmission system. These parameters are used to calculate the insulation withstand voltage of the symmetrical monopole flexible DC transmission system. It is important to note that the target grid-side rated voltage refers to the grid-side rated voltage of the flexible DC transformer, the target valve-side rated voltage refers to the valve-side rated voltage of the flexible DC transformer, and the grid-side arrester lightning impulse protection level voltage refers to the grid-side lightning impulse protection level of the flexible DC transformer.

[0062] Voltage model construction parameters refer to the model parameters used to construct the transient voltage model. Specifically, they include the grid-side rated voltage data, the three-phase voltage initial phase angle data, the valve-side rated voltage data, the angular frequency, and the rated pole-to-ground DC voltage data.

[0063] In an embodiment of the present invention, in response to a received user request for calculating the withstand voltage of a flexible DC transformer, a symmetrical monopole flexible DC transmission system corresponding to the user request information is determined, and corresponding target input parameters and voltage model construction parameters are obtained.

[0064] Step 102: construct a transient voltage model using voltage model construction parameters.

[0065] The transient voltage model refers to the mathematical model used to obtain insulation withstand voltage data.

[0066] In the embodiment of the present invention, a transient voltage model is constructed according to the acquired voltage model construction parameters.

[0067] Step 103: Use target input parameters to input a transient voltage model to generate corresponding insulation withstand voltage data.

[0068] Insulation withstand voltage data refers to one of the parameters used to calculate the target withstand voltage.

[0069] In an embodiment of the present invention, the acquired target input parameters are input into a constructed transient voltage model, thereby outputting corresponding insulation withstand voltage data.

[0070] Step 104: Search a preset margin coefficient key-value pair database according to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, and match the target margin coefficient corresponding to the insulation withstand voltage data.

[0071] Device type refers to the device type corresponding to the flexible DC transformer.

[0072] The margin coefficient key-value pair database refers to a key-value pair database established based on the association between the device type corresponding to each component device in the symmetrical monopole flexible direct current transmission system and the target margin coefficient, wherein the device type corresponding to each component device in the symmetrical monopole flexible direct current transmission system serves as the key and the target margin coefficient serves as the value.

[0073] The target margin coefficient refers to one of the parameters used to calculate the target withstand voltage, and the margin coefficient data is obtained by matching the margin coefficient key-value pair database.

[0074] In an embodiment of the present invention, a preset margin coefficient key-value pair database is retrieved according to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, and a target margin coefficient corresponding to the insulation withstand voltage data is matched.

[0075] Step 105: Calculate the target withstand voltage using the insulation withstand voltage data and the target margin coefficient.

[0076] In the embodiment of the present invention, the acquired insulation withstand voltage data is multiplied by the target margin coefficient to obtain the target withstand voltage.

[0077] In an embodiment of the present invention, in response to received user request information, a symmetrical monopole flexible direct current transmission system corresponding to the user request information is determined and corresponding target input parameters and voltage model construction parameters are obtained, a transient voltage model is constructed using the voltage model construction parameters, the target input parameters are input into the transient voltage model, corresponding insulation withstand voltage data is generated, a preset margin coefficient key-value pair database is retrieved according to the device type of the flexible direct current transformer in the symmetrical monopole flexible direct current transmission system, the target margin coefficient corresponding to the insulation withstand voltage data is matched, and the target withstand voltage is calculated using the insulation withstand voltage data and the target margin coefficient; the technical problems of the existing method, such as the complex modeling structure, the need to model the entire direct current system in order to consider the insulation level of the connected transformer equipment, the large workload of the working condition scanning, the slow calculation speed, and the low efficiency are solved; by establishing a mathematical model of the instantaneous voltage of the overvoltage mechanism between the grid side and the valve side of the flexible direct current transformer in the flexible direct current system, the withstand voltage required by its insulation level can be quickly and accurately calculated. After obtaining the rated voltages on the grid and valve sides of the project's flexible DC transformer, the rated DC voltage, and the lightning impulse protection level parameters of the flexible DC transformer's grid-side winding to ground, the transient voltage model can be used to obtain the maximum operating and lightning overvoltages between the grid and valve sides of the flexible DC transformer, greatly shortening the overvoltage calculation time.

[0078] See also Figure 2 , Figure 2 This is a flowchart of a method for calculating the withstand voltage of a flexible DC transformer provided in the second embodiment of the present invention.

[0079] The present invention provides a method for calculating the withstand voltage of a flexible DC transformer, comprising:

[0080] Step 201: In response to received user request information, determine the symmetrical monopole flexible direct current transmission system corresponding to the user request information and obtain corresponding target input parameters and voltage model building parameters.

[0081] In the embodiment of the present invention, the specific implementation process of step 201 is similar to that of step 101 and will not be repeated here.

[0082] It is worth mentioning that the target input parameters are shown in the following table:

[0083]

[0084] Step 202: construct a transient voltage model using voltage model construction parameters.

[0085] Furthermore, the voltage model construction parameters include grid-side rated voltage data, three-phase voltage initial phase angle data, valve-side rated voltage data, angular frequency, and rated pole-to-ground DC voltage data. Step 202 may further include the following sub-steps:

[0086] S11. Construct a target grid-side three-phase transient voltage model using the initial phase angle data, angular frequency, and grid-side rated voltage data of the three-phase voltage.

[0087] Furthermore, S1 may further include the following sub-steps:

[0088] S111. Construct an initial grid-side a-phase voltage transient model using the initial phase angle data, angular frequency, and grid-side rated voltage data of the a-phase voltage.

[0089] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the initial grid-side a phase voltage transient model can be as follows:

[0090]

[0091] Where U wa Indicates the instantaneous value of phase a voltage on the grid side of the flexible DC transformer, θ a It represents the initial phase angle of phase a voltage, which is 120° apart, and w represents the angular frequency.

[0092] S112. Construct an initial grid-side b-phase voltage transient model using the b-phase voltage initial phase angle data, angular frequency, and grid-side rated voltage data.

[0093] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the initial grid-side b-phase voltage transient model can be as follows:

[0094]

[0095] Where U wb Indicates the instantaneous value of phase b voltage on the grid side of the flexible DC transformer, θ b Indicates the initial phase angle of phase b voltage.

[0096] S113 , constructing an initial grid-side c-phase voltage transient model using the c-phase voltage initial phase angle data, angular frequency, and grid-side rated voltage data.

[0097] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the initial grid-side c-phase voltage transient model can be as follows:

[0098]

[0099] Where U wc Indicates the instantaneous value of phase C voltage on the grid side of the flexible DC transformer, θ c Indicates the initial phase angle of phase C voltage.

[0100] S114 , constructing a target grid-side three-phase instantaneous voltage model using the initial grid-side phase a voltage instantaneous model, the initial grid-side phase b voltage instantaneous model, and the initial grid-side phase c voltage instantaneous model.

[0101] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the target grid-side three-phase transient voltage model can be calculated as follows:

[0102]

[0103] S12. Construct a target valve-side three-phase transient voltage model using the three-phase voltage initial phase angle data, angular frequency, rated pole-to-ground DC voltage data, and valve-side rated voltage data.

[0104] S121. Construct an initial valve side a phase voltage transient model using the a phase voltage initial phase angle data, angular frequency, and valve side rated voltage data.

[0105] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the initial valve side a phase voltage transient model can be as follows:

[0106]

[0107] Where U va1 Indicates the instantaneous value of the initial valve-side a-phase voltage of the flexible DC transformer.

[0108] S122. Construct a target valve side a phase voltage transient model using the initial valve side a phase voltage transient model and the rated pole-to-ground DC voltage data.

[0109] It is worth mentioning that since the grid-side neutral point is directly grounded and the valve-side neutral point is high-resistance grounded, when a DC pole line fault occurs, the grid-side voltage remains unchanged, and the valve-side voltage is the superposition of the AC component and the DC component, thus obtaining the target valve-side phase a voltage instantaneous model:

[0110] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the target valve side a phase voltage transient model can be as follows:

[0111]

[0112] Where U va Indicates the instantaneous value of phase A voltage on the target valve side of the flexible DC transformer.

[0113] S123. Construct an initial valve side b-phase voltage transient model using the b-phase voltage initial phase angle data, angular frequency, and valve side rated voltage data.

[0114] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the initial valve side b-phase voltage transient model can be as follows:

[0115]

[0116] Where U vb1 Indicates the instantaneous value of the initial valve-side b-phase voltage of the flexible DC transformer.

[0117] S124. Construct a target valve side b-phase voltage transient model using the initial valve side b-phase voltage transient model and the rated pole-to-ground DC voltage data.

[0118] It is worth mentioning that since the grid-side neutral point is directly grounded and the valve-side neutral point is high-resistance grounded, when a DC pole line fault occurs, the grid-side voltage remains unchanged, and the valve-side voltage is the superposition of the AC component and the DC component, thus obtaining the target valve-side b-phase voltage instantaneous model:

[0119] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the target valve side b-phase voltage transient model can be as follows:

[0120]

[0121] Where U vb Indicates the instantaneous value of the b-phase voltage on the target valve side of the flexible DC transformer.

[0122] S125. Construct an initial valve side C phase voltage transient model using the C phase voltage initial phase angle data, angular frequency and valve side rated voltage data.

[0123] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the initial valve side c-phase voltage transient model can be as follows:

[0124]

[0125] Where U vc1 Indicates the instantaneous value of the initial valve-side C-phase voltage of the flexible DC transformer.

[0126] S126. Construct a target valve side C-phase voltage transient model using the initial valve side C-phase voltage transient model and the rated pole-to-ground DC voltage data.

[0127] It is worth mentioning that since the grid-side neutral point is directly grounded and the valve-side neutral point is high-resistance grounded, when a DC pole line fault occurs, the grid-side voltage remains unchanged, and the valve-side voltage is the superposition of the AC component and the DC component, thus obtaining the target valve-side C-phase voltage transient model.

[0128] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the target valve side c-phase voltage transient model can be as follows:

[0129]

[0130] Where U vc Indicates the instantaneous value of the C-phase voltage on the target valve side of the flexible DC transformer.

[0131] S127. Construct a three-phase instantaneous voltage model on the target valve side using the target valve side a phase voltage instantaneous model, the target valve side b phase voltage instantaneous model, and the target valve side c phase voltage instantaneous model.

[0132] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the target valve-side three-phase transient voltage model can be calculated as follows:

[0133]

[0134] S13. Construct a transient voltage model using the target grid-side three-phase transient voltage model and the target valve-side three-phase transient voltage model.

[0135] In an example of the present invention, in a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the calculation method of the transient voltage model can be as follows:

[0136]

[0137] In the embodiment of the present invention, a transient voltage model is constructed according to a target grid-side three-phase transient voltage model and a target valve-side three-phase transient voltage model.

[0138] Step 203: Use target input parameters to input a transient voltage model to generate corresponding insulation withstand voltage data.

[0139] Furthermore, the target input parameters include a target grid-side rated voltage, a target valve-side rated voltage, a target rated pole-to-ground DC voltage, and a grid-side arrester lightning impulse protection level voltage; the insulation withstand voltage data include a maximum switching overvoltage between same-phase grid-side valves, a maximum switching overvoltage between phases grid-side valves, and a maximum lightning impulse voltage between same phases on the grid-side valve side. Step 203 may further include the following sub-steps:

[0140] S21. Use the target grid-side rated voltage, the target valve-side rated voltage, and the target rated pole-to-ground DC voltage to input the transient voltage model to generate the corresponding maximum switching overvoltage between the same-phase grid-side valve sides.

[0141] It is worth mentioning that for the same-phase grid-side valve-side switching overvoltage, the absolute value can be obtained by subtracting the instantaneous voltage between the grid side and the valve side of each phase, and considering the case where the electrical angle is 90°, the U va -U wa The maximum operating overvoltage between the valve sides on the same-phase grid side can be obtained.

[0142] In a specific implementation, in order to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the maximum switching overvoltage between the valve sides of the same-phase network side can be calculated as follows:

[0143]

[0144] Where U wv(a-a，SI) Indicates the maximum operating overvoltage between valves on the same-phase network side.

[0145] S22. Use the target grid-side rated voltage, the target valve-side rated voltage, and the target rated pole-to-ground DC voltage to input the transient voltage model to generate the corresponding maximum value of the phase-to-phase grid-side and valve-side switching overvoltage.

[0146] It is worth mentioning that using U vb -U wa The maximum operating overvoltage between the phase-to-phase grid-side and valve-to-valve sides can be obtained.

[0147] In a specific implementation, in order to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form, and the maximum value of the switching overvoltage between the phase-to-grid side valve sides can be calculated as follows:

[0148]

[0149] Where U wv(a-b，SI) Indicates the maximum value of the operating overvoltage between the phase-to-grid side and the valve side.

[0150] S23. Use the target valve-side rated voltage and the grid-side arrester lightning impulse protection level voltage to input the transient voltage model to generate the corresponding maximum value of the grid-side valve-side same-phase lightning impulse voltage.

[0151] It is worth mentioning that when the grid side phase a is struck by lightning, assuming that the grid side phase voltage rises to the lightning impulse protection level U Li , then the lightning impulse overvoltage between the grid side and the valve side in the same phase is U Li -U va , considering it strictly, the valve side voltage is at its peak position at the moment of lightning strike, and the grid side lightning impulse voltage is opposite in polarity to the valve side. At this time, the maximum lightning impulse voltage between the same phases on the grid side and the valve side can be obtained.

[0152] In a specific implementation, to facilitate the implementation of the method, the above process can be converted into a formula encapsulation form. The maximum lightning impulse voltage between the same phases on the grid-side and valve-side can be calculated as follows:

[0153]

[0154] Where U wv(a-a，LI) Indicates the maximum value of the lightning impulse voltage between the same phases on the grid side and the valve side.

[0155] It is worth mentioning that the maximum value of lightning impulse overvoltage between different phases on the grid side and the valve side can be considered to be equal to the maximum value between the same phases.

[0156] Furthermore, the target margin factor includes a switching impulse insulation margin factor and a lightning impulse insulation margin factor.

[0157] Step 204: Use the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system to generate a corresponding composite key.

[0158] A composite key refers to a key composed of device types input into the margin coefficient key-value pair database. The composed key is used to construct a composite filtering condition.

[0159] In the embodiment of the present invention, the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system is used to generate a corresponding composite key.

[0160] Step 205: input the composite key into a preset margin coefficient key-value pair database to match the switching impulse insulation margin coefficient and the lightning impulse insulation margin coefficient corresponding to the insulation withstand voltage data.

[0161] The margin coefficient key-value pair database is as follows:

[0162]

[0163]

[0164] Step 206: Calculate the target withstand voltage using the insulation withstand voltage data and the target margin coefficient.

[0165] Furthermore, the target withstand voltage includes the operating impulse insulation withstand voltage between the same-phase grid-side valves, the operating impulse insulation withstand voltage between the phase grid-side valves, and the lightning impulse insulation withstand voltage between the same phases on the grid-side valves. Step 206 may further include the following sub-steps:

[0166] S31. Calculate the product of the maximum switching overvoltage between valve sides on the same-phase grid side and the switching impulse insulation margin coefficient to generate a corresponding switching impulse insulation withstand voltage between valve sides on the same-phase grid side.

[0167] In the embodiment of the present invention, the maximum switching overvoltage between the same-phase network-side valve sides is multiplied by the switching impulse insulation margin coefficient to generate the corresponding switching impulse insulation withstand voltage between the same-phase network-side valve sides.

[0168] S32. Calculate the product of the maximum switching overvoltage between the phase-to-grid side valve sides and the switching impulse insulation margin coefficient to generate a corresponding switching impulse insulation withstand voltage between the phase-to-grid side valve sides.

[0169] In the embodiment of the present invention, the maximum switching overvoltage between the phase-to-grid side valve sides is multiplied by the switching impulse insulation margin coefficient to generate the corresponding switching impulse insulation withstand voltage between the phase-to-grid side valve sides.

[0170] S33. Calculate the product of the maximum lightning impulse voltage between the same phases on the grid-side valve side and the lightning impulse insulation margin coefficient to generate the corresponding lightning impulse insulation withstand voltage between the same phases on the grid-side valve side.

[0171] In the embodiment of the present invention, the maximum lightning impulse voltage between the same phases on the grid-side valve side is multiplied by the lightning impulse insulation margin coefficient to generate the corresponding lightning impulse insulation withstand voltage between the same phases on the grid-side valve side.

[0172] In a specific example of the present invention:

[0173]

[0174] By inputting the target grid-side rated voltage, target valve-side rated voltage, target rated pole-to-ground DC voltage and grid-side arrester lightning impulse protection level voltage into the transient voltage model, the maximum switching overvoltage between the same-phase grid-side valve sides is 520.4 kV, the maximum switching overvoltage between the phase-to-phase grid-side valve sides is 1260.2 kV, and the maximum lightning impulse voltage between the same phases on the grid-side valve side is 1355.0 kV.

[0175] Based on the matching switching impulse insulation margin factor of 1.15 and lightning impulse insulation margin factor of 1.2, the switching impulse insulation withstand voltage between the same phase and the grid-side valve of the flexible DC transformer is 599kV, and the switching impulse insulation withstand voltage between the phase and the grid-side valve is 1450kV. The lightning impulse insulation withstand voltage between the same phase and the grid-side valve is 1626kV.

[0176] In an embodiment of the present invention, in response to received user request information, a symmetrical monopole flexible direct current transmission system corresponding to the user request information is determined and corresponding target input parameters and voltage model construction parameters are obtained, a transient voltage model is constructed using the voltage model construction parameters, the target input parameters are input into the transient voltage model, corresponding insulation withstand voltage data is generated, a preset margin coefficient key-value pair database is retrieved according to the device type of the flexible direct current transformer in the symmetrical monopole flexible direct current transmission system, the target margin coefficient corresponding to the insulation withstand voltage data is matched, and the target withstand voltage is calculated using the insulation withstand voltage data and the target margin coefficient; the technical problems of the existing method, such as the complex modeling structure, the need to model the entire direct current system in order to consider the insulation level of the connected transformer equipment, the large workload of the working condition scanning, the slow calculation speed, and the low efficiency are solved; by establishing a mathematical model of the instantaneous voltage of the overvoltage mechanism between the grid side and the valve side of the flexible direct current transformer in the flexible direct current system, the withstand voltage required by its insulation level can be quickly and accurately calculated. After obtaining the rated voltages on the grid and valve sides of the project's flexible DC transformer, the rated DC voltage, and the lightning impulse protection level parameters of the flexible DC transformer's grid-side winding to ground, the transient voltage model can be used to obtain the maximum operating and lightning overvoltages between the grid and valve sides of the flexible DC transformer, greatly shortening the overvoltage calculation time.

[0177] See also Figure 3 , Figure 3 This is a structural block diagram of a device for calculating the withstand voltage of a flexible DC transformer provided in the third embodiment of the present invention.

[0178] An embodiment of the present invention provides a device for calculating the withstand voltage of a flexible DC transformer, comprising:

[0179] The response module 301 is configured to respond to the received user request information, determine the symmetrical monopole flexible direct current transmission system corresponding to the user request information, and obtain corresponding target input parameters and voltage model construction parameters.

[0180] The transient voltage model building module 302 is configured to build a transient voltage model using voltage model building parameters.

[0181] The insulation withstand voltage data acquisition module 303 is configured to input a transient voltage model using target input parameters to generate corresponding insulation withstand voltage data.

[0182] The target margin coefficient acquisition module 304 is used to search a preset margin coefficient key-value pair database according to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, and match the target margin coefficient corresponding to the insulation withstand voltage data.

[0183] The target withstand voltage acquisition module 305 is configured to calculate the target withstand voltage using the insulation withstand voltage data and the target margin coefficient.

[0184] Furthermore, the voltage model construction parameters include grid-side rated voltage data, three-phase voltage initial phase angle data, valve-side rated voltage data, angular frequency, and rated pole-to-ground DC voltage data. The transient voltage model construction module 302 includes:

[0185] The target grid-side three-phase transient voltage model construction submodule is used to construct the target grid-side three-phase transient voltage model using the three-phase voltage initial phase angle data, angular frequency and grid-side rated voltage data.

[0186] The target valve-side three-phase transient voltage model construction submodule is used to construct the target valve-side three-phase transient voltage model using the three-phase voltage initial phase angle data, angular frequency, rated pole-to-ground DC voltage data and valve-side rated voltage data.

[0187] The first construction submodule is used to construct a transient voltage model using a target grid-side three-phase transient voltage model and a target valve-side three-phase transient voltage model.

[0188] Furthermore, the three-phase voltage initial phase angle data includes the a-phase voltage initial phase angle data, the b-phase voltage initial phase angle data, and the c-phase voltage initial phase angle data. The target grid-side three-phase transient voltage model construction submodule includes:

[0189] The initial grid-side phase a voltage transient model unit is used to construct an initial grid-side phase a voltage transient model using the initial phase angle data, angular frequency and grid-side rated voltage data of the phase a voltage.

[0190] The initial grid-side b-phase voltage transient model unit is used to construct an initial grid-side b-phase voltage transient model by using the initial phase angle data, angular frequency and grid-side rated voltage data of the b-phase voltage.

[0191] The initial grid-side C-phase voltage transient model unit is used to construct an initial grid-side C-phase voltage transient model by using the initial phase angle data, angular frequency and grid-side rated voltage data of the C-phase voltage.

[0192] The first construction unit is used to construct a target grid-side three-phase instantaneous voltage model by using an initial grid-side phase a voltage instantaneous model, an initial grid-side phase b voltage instantaneous model, and an initial grid-side phase c voltage instantaneous model.

[0193] Furthermore, the target valve-side three-phase transient voltage model construction submodule includes:

[0194] The initial valve side a-phase voltage transient model unit is used to construct an initial valve side a-phase voltage transient model by using the initial phase angle data, angular frequency and valve side rated voltage data of the a-phase voltage.

[0195] The target valve side a-phase voltage transient model unit is used to construct a target valve side a-phase voltage transient model by using the initial valve side a-phase voltage transient model and the rated pole-to-ground DC voltage data.

[0196] The initial valve side b-phase voltage transient model unit is used to construct an initial valve side b-phase voltage transient model by using the b-phase voltage initial phase angle data, angular frequency and valve side rated voltage data.

[0197] The target valve side b-phase voltage transient model unit is used to construct a target valve side b-phase voltage transient model by using the initial valve side b-phase voltage transient model and the rated pole-to-ground DC voltage data.

[0198] The initial valve side C-phase voltage transient model unit is used to construct an initial valve side C-phase voltage transient model by using the initial phase angle data, angular frequency and valve side rated voltage data of the C-phase voltage.

[0199] The target valve side C-phase voltage transient model unit is used to construct a target valve side C-phase voltage transient model by using the initial valve side C-phase voltage transient model and the rated pole-to-ground DC voltage data.

[0200] The second construction unit is used to construct a target valve side three-phase transient voltage model by using a target valve side a-phase voltage transient model, a target valve side b-phase voltage transient model and a target valve side c-phase voltage transient model.

[0201] Furthermore, the target input parameters include the target grid-side rated voltage, the target valve-side rated voltage, the target rated pole-to-ground DC voltage, and the grid-side arrester lightning impulse protection level voltage. The insulation withstand voltage data includes the maximum switching overvoltage between the same-phase grid-side valves, the maximum switching overvoltage between the phase-to-phase grid-side valves, and the maximum lightning impulse voltage between the same phases on the grid-side valves. The insulation withstand voltage data acquisition module 303 includes:

[0202] The submodule of maximum switching overvoltage between valve sides on the same phase grid side is used to input the transient voltage model by using the target grid side rated voltage, the target valve side rated voltage and the target rated pole-to-ground DC voltage to generate the corresponding maximum switching overvoltage between valve sides on the same phase grid side.

[0203] The phase-to-grid side valve-to-valve side switching overvoltage maximum value submodule is used to use the target grid-side rated voltage, the target valve-side rated voltage and the target rated pole-to-ground DC voltage to input the transient voltage model and generate the corresponding phase-to-grid side valve-to-valve side switching overvoltage maximum value.

[0204] The grid-side valve-side same-phase lightning impulse voltage maximum value submodule is used to use the target valve-side rated voltage and the grid-side lightning arrester lightning impulse protection level voltage input transient voltage model to generate the corresponding grid-side valve-side same-phase lightning impulse voltage maximum value.

[0205] Furthermore, the target margin coefficient includes an operating impulse insulation margin coefficient and a lightning impulse insulation margin coefficient. The target margin coefficient acquisition module 304 includes:

[0206] The composite key submodule is used to generate corresponding composite keys for the equipment type of flexible DC transformer in a symmetrical monopole flexible DC transmission system.

[0207] The matching submodule is used to input the composite key into a preset margin coefficient key-value pair database to match the switching impulse insulation margin coefficient and the lightning impulse insulation margin coefficient corresponding to the insulation withstand voltage data.

[0208] Furthermore, the target withstand voltage includes the same-phase grid-side valve-side operation impulse insulation withstand voltage, the phase-to-phase grid-side valve-side operation impulse insulation withstand voltage, and the grid-side valve-side same-phase lightning impulse insulation withstand voltage. The target withstand voltage acquisition module 305 includes:

[0209] The switching impulse insulation withstand voltage submodule between the valve sides on the same phase network is used to calculate the product of the maximum switching overvoltage between the valve sides on the same phase network and the switching impulse insulation margin coefficient to generate the corresponding switching impulse insulation withstand voltage between the valve sides on the same phase network.

[0210] The phase-to-grid side valve-to-valve switching impulse insulation withstand voltage submodule is used to calculate the product of the maximum switching overvoltage between the phase-to-grid side valves and the switching impulse insulation margin coefficient to generate the corresponding phase-to-grid side valve-to-valve switching impulse insulation withstand voltage.

[0211] The grid-side valve-side same-phase lightning impulse insulation withstand voltage submodule is used to calculate the product of the maximum grid-side valve-side same-phase lightning impulse voltage and the lightning impulse insulation margin coefficient to generate the corresponding grid-side valve-side same-phase lightning impulse insulation withstand voltage.

[0212] In an embodiment of the present invention, in response to received user request information, a symmetrical monopole flexible direct current transmission system corresponding to the user request information is determined and corresponding target input parameters and voltage model construction parameters are obtained, a transient voltage model is constructed using the voltage model construction parameters, the target input parameters are input into the transient voltage model, corresponding insulation withstand voltage data is generated, a preset margin coefficient key-value pair database is retrieved according to the device type of the flexible direct current transformer in the symmetrical monopole flexible direct current transmission system, the target margin coefficient corresponding to the insulation withstand voltage data is matched, and the target withstand voltage is calculated using the insulation withstand voltage data and the target margin coefficient; the technical problems of the existing method, such as the complex modeling structure, the need to model the entire direct current system in order to consider the insulation level of the connected transformer equipment, the large workload of the working condition scanning, the slow calculation speed, and the low efficiency are solved; by establishing a mathematical model of the instantaneous voltage of the overvoltage mechanism between the grid side and the valve side of the flexible direct current transformer in the flexible direct current system, the withstand voltage required by its insulation level can be quickly and accurately calculated. After obtaining the rated voltages on the grid and valve sides of the project's flexible DC transformer, the rated DC voltage, and the lightning impulse protection level parameters of the flexible DC transformer's grid-side winding to ground, the transient voltage model can be used to obtain the maximum operating and lightning overvoltages between the grid and valve sides of the flexible DC transformer, greatly shortening the overvoltage calculation time.

[0213] An electronic device according to an embodiment of the present invention includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor executes the method for calculating the withstand voltage of a flexible DC transformer according to any of the above embodiments.

[0214] The memory can be an electronic memory such as a flash memory, an EEPROM (Electrically Erasable Programmable Read-Only Memory), an EPROM, a hard disk, or a ROM. The memory has storage space for program codes for executing any of the method steps in the above method. For example, the storage space for program codes can include individual program codes for implementing the various steps in the above method. These program codes can be read from or written to one or more computer program products. These computer program products include program code carriers such as a hard disk, a compact disc (CD), a memory card, or a floppy disk. The program code can, for example, be compressed in an appropriate form. When these codes are run by a computing and processing device, they cause the computing and processing device to execute the various steps in the above-described method.

[0215] An embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed, the method for calculating the withstand voltage of a flexible DC transformer according to any embodiment of the present invention is implemented.

[0216] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0217] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0218] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0219] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0220] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0221] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the withstand voltage of a flexible DC transformer, characterized in that: include: In response to the received user request information, determining the symmetrical monopole flexible direct current transmission system corresponding to the user request information and obtaining corresponding target input parameters and voltage model construction parameters; constructing a transient voltage model using the voltage model construction parameters; The voltage model construction parameters include grid-side rated voltage data, three-phase voltage initial phase angle data, valve-side rated voltage data, angular frequency, and rated pole-to-ground DC voltage data. The step of using the voltage model construction parameters to construct a transient voltage model includes: Constructing a target grid-side three-phase transient voltage model using the three-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data; Constructing a target valve-side three-phase transient voltage model using the three-phase voltage initial phase angle data, the angular frequency, the rated pole-to-ground DC voltage data, and the valve-side rated voltage data; Constructing a transient voltage model using the target grid-side three-phase transient voltage model and the target valve-side three-phase transient voltage model; Using the target input parameters to input the transient voltage model to generate corresponding insulation withstand voltage data; The target input parameters include a target grid-side rated voltage, a target valve-side rated voltage, a target rated pole-to-ground DC voltage, and a grid-side arrester lightning impulse protection level voltage; the insulation withstand voltage data include a maximum switching overvoltage between same-phase grid-side valves, a maximum switching overvoltage between phases of grid-side valves, and a maximum lightning impulse voltage between same phases of grid-side valves; and the step of using the target input parameters to input the transient voltage model to generate corresponding insulation withstand voltage data includes: The target grid-side rated voltage, the target valve-side rated voltage, and the target rated pole-to-ground DC voltage are input into the transient voltage model to generate a corresponding maximum switching overvoltage between same-phase grid-side valves; The target grid-side rated voltage, the target valve-side rated voltage, and the target rated pole-to-ground DC voltage are input into the transient voltage model to generate a corresponding maximum value of an inter-phase grid-side and inter-valve-side switching overvoltage; The target valve-side rated voltage and the grid-side arrester lightning impulse protection level voltage are input into the transient voltage model to generate a corresponding maximum value of the grid-side valve-side same-phase lightning impulse voltage; Searching a preset margin coefficient key-value pair database according to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, and matching the target margin coefficient corresponding to the insulation withstand voltage data; The target withstand voltage is calculated using the insulation withstand voltage data and the target margin coefficient.

2. The method for calculating the withstand voltage of a flexible DC transformer according to claim 1, wherein: The three-phase voltage initial phase angle data includes phase A voltage initial phase angle data, phase B voltage initial phase angle data, and phase C voltage initial phase angle data. The step of using the three-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data to construct a target grid-side three-phase transient voltage model includes: Constructing an initial grid-side a-phase voltage transient model using the a-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data; Constructing an initial grid-side b-phase voltage transient model using the b-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data; Constructing an initial grid-side C-phase voltage transient model using the C-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data; The target grid-side three-phase transient voltage model is constructed by using the initial grid-side a-phase transient voltage model, the initial grid-side b-phase transient voltage model, and the initial grid-side c-phase transient voltage model.

3. The method for calculating the withstand voltage of a flexible DC transformer according to claim 2, wherein: The step of constructing a target valve-side three-phase transient voltage model using the three-phase voltage initial phase angle data, the angular frequency, the rated pole-to-ground DC voltage data, and the valve-side rated voltage data includes: Constructing an initial valve-side a-phase voltage transient model using the a-phase voltage initial phase angle data, the angular frequency, and the valve-side rated voltage data; Constructing a target valve-side a-phase voltage transient model using the initial valve-side a-phase voltage transient model and the rated pole-to-ground DC voltage data; Constructing an initial valve-side b-phase voltage transient model using the b-phase voltage initial phase angle data, the angular frequency, and the valve-side rated voltage data; Constructing a target valve-side b-phase voltage transient model using the initial valve-side b-phase voltage transient model and the rated pole-to-ground DC voltage data; Constructing an initial valve-side C-phase voltage transient model using the C-phase voltage initial phase angle data, the angular frequency, and the valve-side rated voltage data; Constructing a target valve-side C-phase voltage transient model using the initial valve-side C-phase voltage transient model and the rated pole-to-ground DC voltage data; The target valve side three-phase transient voltage model is constructed by using the target valve side a-phase transient voltage model, the target valve side b-phase transient voltage model and the target valve side c-phase transient voltage model.

4. The method for calculating the withstand voltage of a flexible DC transformer according to claim 1, wherein: The target margin coefficient includes an operating impulse insulation margin coefficient and a lightning impulse insulation margin coefficient. The step of searching a preset margin coefficient key-value pair database according to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system and matching the target margin coefficient corresponding to the insulation withstand voltage data includes: Using the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, generating a corresponding composite key; The composite key is input into a preset margin coefficient key-value pair database to match the switching impulse insulation margin coefficient and the lightning impulse insulation margin coefficient corresponding to the insulation withstand voltage data.

5. The method for calculating the withstand voltage of a flexible DC transformer according to claim 4, wherein: The target withstand voltage includes an operating impulse insulation withstand voltage between same-phase grid-side valves, an operating impulse insulation withstand voltage between phase grid-side valves, and a lightning impulse insulation withstand voltage between same-phase grid-side valves. The step of calculating the target withstand voltage using the insulation withstand voltage data and the target margin coefficient includes: Calculating the product of the maximum switching overvoltage between the valve sides on the same-phase network side and the switching impulse insulation margin coefficient to generate the corresponding switching impulse insulation withstand voltage between the valve sides on the same-phase network side; Calculating the product of the maximum switching overvoltage between the phase-to-grid side valve sides and the switching impulse insulation margin coefficient to generate the corresponding switching impulse insulation withstand voltage between the phase-to-grid side valve sides; The product of the maximum value of the lightning impulse voltage between the same phases on the grid-side valve side and the lightning impulse insulation margin coefficient is calculated to generate the corresponding lightning impulse insulation withstand voltage between the same phases on the grid-side valve side.

6. A device for calculating the withstand voltage of a flexible DC transformer, characterized in that: include: a response module, configured to, in response to the received user request information, determine the symmetrical monopole flexible direct current transmission system corresponding to the user request information and obtain corresponding target input parameters and voltage model construction parameters; A transient voltage model construction module, configured to construct a transient voltage model using the voltage model construction parameters; The voltage model construction parameters include grid-side rated voltage data, three-phase voltage initial phase angle data, valve-side rated voltage data, angular frequency and rated pole-to-ground DC voltage data. The transient voltage model construction module includes: A target grid-side three-phase transient voltage model construction submodule is configured to construct a target grid-side three-phase transient voltage model using the three-phase voltage initial phase angle data, the angular frequency, and the grid-side rated voltage data; a target valve-side three-phase transient voltage model construction submodule, configured to construct a target valve-side three-phase transient voltage model using the three-phase voltage initial phase angle data, the angular frequency, the rated pole-to-ground DC voltage data, and the valve-side rated voltage data; A first construction submodule is configured to construct a transient voltage model using the target grid-side three-phase transient voltage model and the target valve-side three-phase transient voltage model; an insulation withstand voltage data acquisition module, configured to input the transient voltage model using the target input parameters to generate corresponding insulation withstand voltage data; The target input parameters include the target grid-side rated voltage, the target valve-side rated voltage, the target rated pole-to-ground DC voltage, and the grid-side arrester lightning impulse protection level voltage. The insulation withstand voltage data includes the maximum switching overvoltage between the same-phase grid-side valves, the maximum switching overvoltage between the phase-to-phase grid-side valves, and the maximum lightning impulse voltage between the same phases on the grid-side valves. The insulation withstand voltage data acquisition module includes: a same-phase grid-side valve-side switching overvoltage maximum value submodule, configured to use the target grid-side rated voltage, the target valve-side rated voltage, and the target rated pole-to-ground DC voltage as inputs into the transient voltage model to generate a corresponding same-phase grid-side valve-side switching overvoltage maximum value; a phase-to-grid-side valve-to-valve switching overvoltage maximum value submodule, configured to use the target grid-side rated voltage, the target valve-side rated voltage, and the target rated pole-to-ground DC voltage as inputs into the transient voltage model to generate a corresponding phase-to-grid-side valve-to-valve switching overvoltage maximum value; A submodule for the maximum lightning impulse voltage between the same phases on the grid-side valve side is configured to input the target valve-side rated voltage and the grid-side arrester lightning impulse protection level voltage into the transient voltage model to generate a corresponding maximum lightning impulse voltage between the same phases on the grid-side valve side; a target margin coefficient acquisition module, configured to retrieve a preset margin coefficient key-value pair database according to the device type of the flexible DC transformer in the symmetrical monopole flexible DC transmission system, and match the target margin coefficient corresponding to the insulation withstand voltage data; A target withstand voltage acquisition module is used to calculate a target withstand voltage using the insulation withstand voltage data and the target margin coefficient.

7. An electronic device, characterized in that: The method comprises a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of the method for calculating the withstand voltage of a flexible DC transformer according to any one of claims 1 to 5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed, the method for calculating the withstand voltage of a flexible DC transformer according to any one of claims 1 to 5 is implemented.

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