Flux linkage saturation suppression method and device under flexible direct current converter transformer and sympathetic inrush current

Abstract

The invention provides a flux linkage saturation suppression method and device under a flexible direct current converter transformer and sympathetic inrush current. The flux linkage saturation suppression method under the flexible direct current converter transformer and the sympathetic inrush current comprises the following steps: determining a flux linkage of the flexible direct current converter transformer according to grid-side electrical characteristic parameters of the flexible direct current converter transformer; extracting a direct-current component of the flux linkage through a pre-generated low-pass filter; and generating a saturation criterion of the flexible DC converter transformer according to the DC component so as to suppress the flux linkage DC bias of the flexible DC converter transformer. According to the invention, the desaturation operation is carried out on the running converter transformer through the flexible direct current converter transformer, so that the magnitude of the sympathetic inrush current is reduced, and the safe operation of the flexible direct current system is ensured.

Description

Technical Field

[0001] The present application belongs to the field of flexible direct current transmission technology, and in particular to the field of relay protection technology for main equipment of power system during flexible direct current transmission, and in particular to a method and device for suppressing magnetic flux saturation under a flexible direct current converter transformer and a surge current. Background Art

[0002] Flexible direct current transmission has the characteristics of flexible control and good power quality, and has great advantages in the fields of asynchronous interconnection of AC power grids and offshore wind power transmission. With the increase in the capacity of the transmission system, the flexible direct current system mostly adopts a true bipolar topology structure, and the two-pole converters can be switched and operated independently, which improves the equipment utilization rate and economic benefits of the flexible direct current system. However, the true bipolar topology structure also brings some problems. Since the AC sides of the two poles of the true bipolar system are connected to the same common bus, when the converter transformer of one pole is put into operation without load, it often generates a large excitation inrush current, and at the same time, it will cause the converter transformer of the other pole to generate a response inrush current, thereby affecting the safe operation of the flexible direct current system. Summary of the invention

[0003] The method and device for suppressing flux saturation under inrush current of a flexible DC converter transformer provided by the present invention desaturate the operating converter transformer through the flexible DC converter transformer to reduce the inrush current, thereby ensuring the safe operation of the flexible DC system.

[0004] In order to solve the technical problems in the background technology of this application, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides a flexible DC converter transformer and a method for suppressing flux saturation under inrush current, the method comprising:

[0006] Determining the flux linkage of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer;

[0007] extracting a DC component of the flux linkage by a pre-generated low-pass filter;

[0008] A saturation criterion of the flexible DC converter transformer is generated according to the DC component to suppress the DC bias of the flux linkage of the flexible DC converter transformer.

[0009] In some embodiments of the present application, generating a saturation criterion of the flexible DC converter transformer according to the DC component includes:

[0010] Normalizing the DC component to generate a per-unit value of the DC component;

[0011] The saturation criterion is generated according to the per-unit value.

[0012] In some embodiments of the present application, the grid-side electrical characteristic parameters include: grid-side current, grid-side voltage, grid-side leakage resistance, grid-side leakage reactance and residual magnetism.

[0013] In some embodiments of the present application, the step of suppressing the flux DC bias of the flexible DC converter transformer includes:

[0014] generating an enable signal for a flux linkage DC bias suppressor according to the saturation criterion;

[0015] The flux DC bias of the flexible DC converter transformer is suppressed according to the enable signal.

[0016] In some embodiments of the present application, a flexible DC converter transformer and a method for suppressing flux saturation under inrush current further include:

[0017] The output voltage of the feedback loop of the flux DC bias suppressor is determined according to the DC component, the proportional coefficient and the integral coefficient of the flux controller.

[0018] In a second aspect, the present invention provides a device for suppressing flux saturation under a flexible DC converter transformer and an inrush current, the device comprising:

[0019] A flux linkage determination module, used to determine the flux linkage of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer;

[0020] A DC component extraction module, used to extract the DC component of the flux linkage through a pre-generated low-pass filter;

[0021] The flux DC bias suppression module is used to generate a saturation criterion of the flexible DC converter transformer according to the DC component to suppress the flux DC bias of the flexible DC converter transformer.

[0022] In some embodiments of the present application, the flux DC bias suppression module includes:

[0023] a per-unit value generating unit, used for normalizing the DC component to generate a per-unit value of the DC component;

[0024] A saturation criterion generating unit is used to generate the saturation criterion according to the per-unit value.

[0025] In some embodiments of the present application, the grid-side electrical characteristic parameters include: grid-side current, grid-side voltage, grid-side leakage resistance, grid-side leakage reactance and residual magnetism.

[0026] In some embodiments of the present application, the flux DC bias suppression module further includes:

[0027] An enable signal generating unit, used for generating an enable signal of a flux linkage DC bias suppressor according to the saturation criterion;

[0028] A flux DC bias suppression unit is used to suppress the flux DC bias of the flexible DC converter transformer according to the enable signal.

[0029] In some embodiments of the present application, a flexible DC converter transformer and a device for suppressing flux saturation under surge current further include:

[0030] The output voltage determination module is used to determine the output voltage of the feedback loop of the flux DC bias suppressor according to the DC component, the proportional coefficient and the integral coefficient of the flux controller.

[0031] In a third aspect, the present invention provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of a flexible DC converter transformer and a method for suppressing flux saturation under inrush current.

[0032] In a fourth aspect, the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, steps of a method for suppressing flux saturation of a flexible DC converter transformer and a surge current are implemented.

[0033] In a fifth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a flexible DC converter transformer and a method for suppressing flux saturation under inrush current.

[0034] From the above description, it can be seen that the embodiments of the present invention provide a flexible DC converter transformer and a method and device for suppressing flux saturation under surge current. The corresponding flexible DC converter transformer and the method for suppressing flux saturation under surge current include: first, determining the flux of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer; extracting the DC component of the flux through a pre-generated low-pass filter; generating a saturation criterion of the flexible DC converter transformer according to the DC component to suppress the DC bias of the flux of the flexible DC converter transformer.

[0035] The corresponding flexible DC converter transformer and the device for suppressing flux saturation under surge current include: a flux determination module, used to determine the flux of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer; a DC component extraction module, used to extract the DC component of the flux through a pre-generated low-pass filter; a flux DC bias suppression module, used to generate a saturation criterion of the flexible DC converter transformer according to the DC component to suppress the flux DC bias of the flexible DC converter transformer.

[0036] Firstly, the present invention uses a flexible DC converter to desaturate the converter transformer in operation, thereby reducing the size of the inrush current. Secondly, the present invention does not require additional primary equipment and has low cost. Finally, the present invention actively uses a flux DC bias suppressor when the converter transformer flux is saturated, without affecting the normal operation of the flexible DC system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic diagram of a flexible DC converter transformer and a method for suppressing flux saturation under inrush current in an embodiment of the present invention Figure 1 ;

[0039] Figure 2 FIG. 3 is a flow chart of step 300 of a flexible DC converter transformer and a method for suppressing flux saturation under inrush current in an embodiment of the present invention. Figure 1 ;

[0040] Figure 3 FIG. 3 is a flow chart of a flexible DC converter transformer and a method for suppressing flux saturation under inrush current in an embodiment of the present invention. Figure 2 ;

[0041] Figure 4 A schematic diagram of a flexible DC converter transformer and a method for suppressing flux saturation under inrush current in an embodiment of the present invention Figure 2 ;

[0042] Figure 5 It is a schematic diagram of a flow chart of a flexible DC converter transformer and a method for suppressing flux saturation under inrush current in a specific embodiment of the present invention;

[0043] Figure 6 is a block diagram of a flux control loop in a specific embodiment of the present invention;

[0044] Figure 7 It is a schematic diagram of the excitation current effect of the flexible DC converter transformer in a specific embodiment of the present invention;

[0045] Figure 8 It is a schematic diagram of the suppression effect of the DC component of the flux linkage of the flexible DC converter transformer in a specific embodiment of the present invention;

[0046] Fig. 9A block diagram of a flexible DC converter transformer and a device for suppressing flux saturation under surge current in an embodiment of the present invention Figure 1 ;

[0047] Fig.10 The block diagram of the flux DC bias suppression module 30 in the embodiment of the present invention is Figure 1 ;

[0048] Fig.11 The block diagram of the flux DC bias suppression module 30 in the embodiment of the present invention is Figure 2 ;

[0049] Fig.12 A block diagram of a flexible DC converter transformer and a device for suppressing flux saturation under surge current in an embodiment of the present invention Figure 2 ;

[0050] Fig.13 FIG. 4 is a schematic diagram of the structure of an electronic device in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 described embodiments are 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 creative work are within the scope of protection of the present invention.

[0052] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented 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.

[0053] It should be noted that the terms "including" and "having" in the specification and claims of the present application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices. In the absence of conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0054] In the prior art, most of the solutions to the inrush current of converter transformers are to reduce the magnitude of the inrush current by eliminating or reducing the excitation inrush current generated by the converter transformer when it is closed at no-load. The invention patent with publication number CN108767821B proposes a phase-selective closing and switching method and system. The invention is an improved method of transformer phase-selective closing technology, which is applied to a phase-selective closing device for controlling the circuit breaker of a high-impedance transformer, reduces the excitation inrush current of the high-impedance transformer when it is switched, can improve the closing success rate, and improve the operating efficiency of the power grid.

[0055] The invention patent with publication number CN116646144A discloses an excitation surge current suppression circuit based on residual magnetism elimination and its control method. This method performs controllable demagnetization on the transformer through an additional demagnetization module, which solves the problem that the phase selection closing method has too high control accuracy requirements and still has residual magnetism, and further improves the demagnetization effect of residual magnetism.

[0056] The invention patent with publication number CN108666974B proposes a transformer and excitation inrush current suppression method based on flux linkage control. This method connects a small-capacity DC / AC converter to the secondary winding or auxiliary winding of the transformer. No matter when the transformer is closed, the core flux linkage will be directly in a steady state without a transient process, thereby completely eliminating the excitation inrush current.

[0057] Although the above methods can eliminate or reduce the excitation surge current generated by the no-load closing transformer, thereby reducing the generation of the sum inrush current in the converter transformer, the above methods all require the addition of additional equipment to the original system, so there is a disadvantage of high cost; in addition, the above methods all operate to suppress the generation of the excitation surge current when the converter transformer is no-load closed, thereby reducing the size of the sum inrush current, and cannot directly suppress the sum inrush current generated by the running converter transformer.

[0058] Based on this, the embodiment of the present invention provides a specific implementation of a flexible DC converter transformer and a method for suppressing flux saturation under inrush current, see Figure 1 , the method comprising:

[0059] Step 100: determining the flux linkage of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer;

[0060] Step 200: extracting the DC component of the flux linkage through a pre-generated low-pass filter;

[0061] Step 300: Generate a saturation criterion of the flexible DC converter transformer according to the DC component to suppress the DC bias of the flux linkage of the flexible DC converter transformer.

[0062] From the above description, it can be seen that an embodiment of the present invention provides a flexible DC converter transformer and a method for suppressing flux saturation under surge current, including: first, determining the flux of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer; extracting the DC component of the flux through a pre-generated low-pass filter; generating a saturation criterion of the flexible DC converter transformer according to the DC component to suppress the DC bias of the flux of the flexible DC converter transformer.

[0063] The present invention can desaturate the flux of the converter transformer through the flexible DC converter, reduce the inrush current caused by saturation of the converter transformer, improve the current quality of the flexible DC converter, and facilitate the safe and stable operation of the flexible DC system.

[0064] The flux linkage of the flexible DC converter transformer in step 100 refers to the product of magnetic flux and the number of coil turns. In the flexible DC converter transformer, the change of flux linkage will affect the electromagnetic characteristics of the flexible DC converter transformer, such as voltage, current and power conversion efficiency. The key factors affecting the flux linkage of the flexible DC converter transformer include:

[0065] Magnetic flux density: Magnetic flux density is an important parameter that describes the strength of the magnetic field and is usually expressed in Tesla. The core material and design of the converter transformer will affect the distribution of magnetic flux density.

[0066] Core material: Core materials with high magnetic permeability and low loss can improve the efficiency of the transformer and reduce losses. Common core materials include silicon steel sheets and amorphous alloy materials.

[0067] Turns ratio: The turns ratio between the primary and secondary coils determines the voltage conversion ratio. The turns ratio design needs to consider the power level and operating voltage range of the transformer.

[0068] Hysteresis loop: The hysteresis loop describes the relationship between the magnetic flux density and the magnetic field strength during the magnetization process of the core material. Ideally, the hysteresis loop should be as narrow as possible to reduce hysteresis losses.

[0069] Saturation flux density: This is the flux density when the core material reaches saturation during the magnetization process. The design needs to avoid the core entering saturation to prevent nonlinear distortion and overheating.

[0070] In some embodiments of the present application, see Figure 2 , generating a saturation criterion of the flexible DC converter transformer according to the DC component in step 300 includes:

[0071] Step 301: normalizing the DC component to generate a per-unit value of the DC component;

[0072] Normalization is a process of converting actual physical quantities into dimensionless quantities relative to a certain reference value, so as to facilitate the comparison and calculation of parameters of power systems of different capacities and voltage levels. Its purpose is to simplify the calculation process so that parameters of power systems of different voltage levels and capacities can be compared and analyzed on the same scale.

[0073] Preferably, the steps of normalization are as follows:

[0074] Select benchmark values: Select appropriate benchmark values ​​based on the needs of the analysis. These benchmark values ​​are usually typical values ​​of key parameters in the power system, such as voltage, current, power, etc.

[0075] Convert actual value to per unit value: Divide the actual measured physical quantity by the corresponding reference value to obtain the dimensionless per unit value.

[0076] Comparison of per-unit analysis with other power system analysis methods:

[0077] Advantages: Normalization can simplify the calculation process, allowing the parameters of power systems of different voltage levels and capacities to be compared and analyzed on the same scale, improving the efficiency and accuracy of the analysis.

[0078] Limitations: Normalization depends on the choice of reference values, and different reference values ​​may lead to different results. In addition, although normalization eliminates the influence of units, the expression of physical meaning may not be as intuitive as directly using actual units.

[0079] Step 302: Generate the saturation criterion according to the per-unit value.

[0080] In some embodiments of the present application, the grid-side electrical characteristic parameters include: grid-side current, grid-side voltage, grid-side leakage resistance, grid-side leakage reactance and residual magnetism.

[0081] In some embodiments of the present application, see Figure 3 The step 300 of suppressing the flux DC bias of the flexible DC converter transformer includes:

[0082] Step 303: generating an enable signal of a flux DC bias suppressor according to the saturation criterion;

[0083] Step 304: Suppressing the flux DC bias of the flexible DC converter transformer according to the enable signal.

[0084] Specifically, when the saturation criterion is true, the enable signal of the flux DC bias suppressor is assigned a value of 1; when the saturation criterion is false, the enable signal of the flux DC bias suppressor is assigned a value of 0. Then, the flux DC bias suppressor is input according to the enable signal to suppress the converter transformer flux DC bias.

[0085] In some embodiments of the present application, see Figure 4 , a flexible DC converter transformer and a method for suppressing flux saturation under surge current, further comprising:

[0086] Step 400: Determine the output voltage of the feedback loop of the flux DC bias suppressor according to the DC component, the proportional coefficient and the integral coefficient of the flux controller.

[0087] Specifically, the feedback loop of the flux DC bias suppressor can be expressed as:

[0088]

[0089] in, It is the output voltage of the flux feedback loop, which is added to the voltage output by the current loop and then participates in the modulation; is the given value of the DC component of the flux linkage, which is generally taken as 0; is the DC component of the extracted flux; K p is the proportional coefficient of the flux controller, K i is the integral coefficient of the flux controller.

[0090] From the above description, it can be seen that an embodiment of the present invention provides a flexible DC converter transformer and a method for suppressing flux saturation under surge current, including: collecting the grid-side voltage and current of the converter transformer, estimating the flux of the converter transformer; extracting the estimated DC component of the flux; giving an enable signal of a flux DC bias suppressor according to the DC component of the flux and a saturation criterion; and inputting the flux DC bias suppressor according to the enable signal to suppress the DC bias of the flux of the converter transformer.

[0091] Firstly, the present invention uses a flexible DC converter to desaturate the converter transformer in operation, thereby reducing the size of the inrush current. Secondly, the present invention does not require additional primary equipment and has low cost. Finally, the present invention actively uses a flux DC bias suppressor when the converter transformer flux is saturated, without affecting the normal operation of the flexible DC system.

[0092] To further illustrate the solution, the present invention also provides a specific implementation of a flexible DC converter transformer and a method for suppressing flux saturation under surge current, see Figure 5 , the method includes the following contents:

[0093] S1: Collect the voltage and current on the grid side of the converter transformer and estimate the flux linkage of the converter transformer;

[0094] Collect the voltage and current on the grid side of the converter transformer and estimate the flux of the converter transformer. The flux estimation formula of the converter transformer is:

[0095]

[0096] Among them, u g is the grid-side phase voltage of the converter transformer, i g is the grid-side phase current of the converter transformer, R1 is the grid-side leakage group of the converter transformer, L1 is the grid-side leakage reactance of the converter transformer, It is the residual magnetism of converter transformer.

[0097] S2: Extract the estimated DC component of the flux and standardize it;

[0098] The estimated DC component of the flux is extracted. A low-pass filter is used to extract the DC component of the flux. The transfer function of the single-input single-output low-pass filter is:

[0099]

[0100] ω c =2πf c

[0101] Where, ξ is the damping coefficient; f c is the cut-off frequency. Both parameters need to be adjusted according to the actual situation. Generally, ξ is taken as 0.707 and f is taken as c The DC component of the flux obtained by filtering is 5 to 15 Hz. The DC component of the flux is normalized to per unit, and the normalization formula is:

[0102]

[0103] in, is the reference value of magnetic flux; U B is the voltage reference value, i.e. the phase voltage peak value; ω B It is the reference value of angular velocity, and its general value is 100π.

[0104] S3: giving a flux DC bias suppressor enable signal according to the flux DC component and saturation criterion;

[0105] The flux DC bias suppressor enable signal is given according to the flux DC component and saturation criterion. The converter transformer saturation criterion is:

[0106] S: or

[0107] in, is the per unit value of the DC component of the flux linkage of the converter transformer described in step S2; a and b are judgment thresholds, which are usually set according to the actual equipment, and generally a and b are 0.1 to 0.2. When the judgment criterion S is true, the flux linkage DC bias suppressor enable signal is assigned a value of 1; when the judgment criterion S is false, the flux linkage DC bias suppressor enable signal is assigned a value of 0.

[0108] S4: The flux DC bias suppressor is activated according to the enable signal to suppress the flux DC bias of the converter transformer.

[0109] The flux DC bias suppressor is input according to the enable signal to suppress the flux DC bias of the converter transformer. The feedback loop of the flux DC bias suppressor can be expressed as:

[0110]

[0111] in, It is the voltage output by the flux feedback loop, which participates in the modulation after being added to the voltage output by the current loop; is the given value of the DC component of the flux linkage, which is generally taken as 0; is the DC component of the flux extracted in step S2; K p is the proportional coefficient of the flux controller, K i is the integral coefficient of the flux controller.

[0112] The feedback loop of the flux DC bias suppressor is as follows: Figure 6 As shown, the grid-side phase voltage u is collected g Phase current i g After the flux estimation step, the converter transformer flux is obtained The DC component is extracted by filtering. is the given value of the DC component of the flux, which is taken as 0; and the DC component of the flux extracted by the filter Subtract the voltage output by the PI controller to get the flux feedback loop Then add it to the voltage e output by the traditional grid-connected control loop to get e sum Participate in modulation. The excitation current effect of the flexible DC converter transformer is as follows Figure 7 As shown in the figure, the DC component suppression effect of the flexible DC converter transformer is as follows: Figure 8 shown.

[0113] From the above description, it can be seen that the specific application example of the present invention provides a flexible DC converter transformer and a method for suppressing flux saturation under surge current, including: collecting the grid-side voltage and current of the converter transformer to estimate the flux of the converter transformer; extracting the estimated DC component of the flux; giving an enable signal of a flux DC bias suppressor according to the DC component of the flux and a saturation criterion; and inputting the flux DC bias suppressor according to the enable signal to suppress the DC bias of the flux of the converter transformer.

[0114] Firstly, the present invention uses a flexible DC converter to desaturate the converter transformer in operation, thereby reducing the size of the inrush current. Secondly, the present invention does not require additional primary equipment and has low cost. Finally, the present invention actively uses a flux DC bias suppressor when the converter transformer flux is saturated, without affecting the normal operation of the flexible DC system.

[0115] Based on the same inventive concept, the embodiments of the present application also provide a flexible DC converter transformer and a device for suppressing flux saturation under surge current, which can be used to implement the methods described in the above embodiments, such as the following embodiments. Since the principles of solving problems by the flexible DC converter transformer and the device for suppressing flux saturation under surge current are similar to those of the flexible DC converter transformer and the method for suppressing flux saturation under surge current, the implementation of the flexible DC converter transformer and the device for suppressing flux saturation under surge current can refer to the implementation of the flexible DC converter transformer and the method for suppressing flux saturation under surge current, and the repeated parts will not be repeated. As used below, the terms "unit" or "module" can be a combination of software and / or hardware that implements predetermined functions. Although the system described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0116] The embodiment of the present invention provides a specific implementation of a flexible DC converter transformer and a flux saturation suppression device under surge current that can realize a flexible DC converter transformer and a flux saturation suppression method under surge current, see Fig. 9 A flexible DC converter transformer and a device for suppressing flux saturation under surge current specifically include the following contents:

[0117] A flux linkage determination module 10, configured to determine the flux linkage of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer;

[0118] A DC component extraction module 20, configured to extract the DC component of the flux linkage through a pre-generated low-pass filter;

[0119] The flux DC bias suppression module 30 is used to generate a saturation criterion of the flexible DC converter transformer according to the DC component to suppress the flux DC bias of the flexible DC converter transformer.

[0120] In some embodiments of the present application, see Fig.10 , the flux linkage DC bias suppression module 30 includes:

[0121] A per-unit value generating unit 30a, configured to perform per-unit normalization on the DC component to generate a per-unit value of the DC component;

[0122] The saturation criterion generating unit 30b is used to generate the saturation criterion according to the per-unit value.

[0123] In some embodiments of the present application, the grid-side electrical characteristic parameters include: grid-side current, grid-side voltage, grid-side leakage resistance, grid-side leakage reactance and residual magnetism.

[0124] In some embodiments of the present application, see Fig.11 , the flux linkage DC bias suppression module 30 further includes:

[0125] An enable signal generating unit 30c, used to generate an enable signal of the flux linkage DC bias suppressor according to the saturation criterion;

[0126] The flux DC bias suppression unit 30d is used to suppress the flux DC bias of the flexible DC converter transformer according to the enable signal.

[0127] In some embodiments of the present application, see Fig.12 , a flexible DC converter transformer and a device for suppressing flux saturation under surge current, further comprising:

[0128] The output voltage determination module 40 is used to determine the output voltage of the feedback loop of the flux DC bias suppressor according to the DC component, the proportional coefficient and the integral coefficient of the flux controller.

[0129] From the above description, it can be seen that an embodiment of the present invention provides a flexible DC converter transformer and a device for suppressing flux saturation under surge current, including: a flux determination module, used to determine the flux of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer; a DC component extraction module, used to extract the DC component of the flux through a pre-generated low-pass filter; a flux DC bias suppression module, used to generate a saturation criterion of the flexible DC converter transformer according to the DC component, so as to suppress the flux DC bias of the flexible DC converter transformer.

[0130] Firstly, the present invention uses a flexible DC converter to desaturate the converter transformer in operation, thereby reducing the size of the inrush current. Secondly, the present invention does not require additional primary equipment and has low cost. Finally, the present invention actively uses a flux DC bias suppressor when the converter transformer flux is saturated, without affecting the normal operation of the flexible DC system.

[0131] The embodiments of the present application also provide a specific implementation of an electronic device capable of implementing all steps in the flexible DC converter transformer and the method for suppressing flux saturation under inrush current in the above embodiments, see Fig.13 , electronic equipment specifically includes the following:

[0132] Processor (processor) 1201, memory (memory) 1202, communication interface (CommunicationsInterface) 1203 and bus 1204;

[0133] The processor 1201, the memory 1202, and the communication interface 1203 communicate with each other through the bus 1204; the communication interface 1203 is used to realize information transmission between the server device and the client device and other related devices;

[0134] The processor 1201 is used to call the computer program in the memory 1202. When the processor executes the computer program, all the steps in the flexible DC converter transformer and the method for suppressing flux saturation under inrush current in the above embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0135] Step 100: determining the flux linkage of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer;

[0136] Step 200: extracting the DC component of the flux linkage through a pre-generated low-pass filter;

[0137] Step 300: Generate a saturation criterion of the flexible DC converter transformer according to the DC component to suppress the DC bias of the flux linkage of the flexible DC converter transformer.

[0138] The embodiments of the present application also provide a computer-readable storage medium capable of implementing all the steps in the flexible DC converter transformer and the method for suppressing flux saturation under surge current in the above embodiments. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the flexible DC converter transformer and the method for suppressing flux saturation under surge current in the above embodiments are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0139] Step 100: determining the flux linkage of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer;

[0140] Step 200: extracting the DC component of the flux linkage through a pre-generated low-pass filter;

[0141] Step 300: Generate a saturation criterion of the flexible DC converter transformer according to the DC component to suppress the DC bias of the flux linkage of the flexible DC converter transformer.

[0142] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0143] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0144] Although the present application provides method operation steps such as embodiments or flow charts, more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the order of many steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in the order of the method shown in the embodiments or the drawings or in parallel (for example, in a parallel processor or multi-threaded processing environment).

[0145] For the convenience of description, the above devices are described in various modules according to their functions. Of course, when implementing the embodiments of this specification, the functions of each module can be implemented in the same or more software and / or hardware, or the module implementing the same function can be implemented by a combination of multiple sub-modules or sub-units. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, 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 through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0146] Those skilled in the art also know that, in addition to implementing the controller in a purely computer-readable program code, the controller can be made to implement the same function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, such a controller can be considered as a hardware component, and the devices for implementing various functions included therein can also be considered as structures within the hardware component. Or even, the devices for implementing various functions can be considered as both software modules for implementing the method and structures within the hardware component.

[0147] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0148] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0149] The present specification embodiments may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The present specification embodiments may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0150] Each embodiment in this specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. In the description of this specification, the description of the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of this specification. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, in the absence of contradiction, a person skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0151] The above is only an example of the embodiment of the present specification and is not intended to limit the embodiment of the present specification. For those skilled in the art, the embodiment of the present specification may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiment of the present specification shall be included in the scope of the claims of the embodiment of the present specification.

Claims

1. A flexible DC converter transformer and a method for suppressing flux saturation under inrush current, characterized in that: include: Determining the flux linkage of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer; extracting a DC component of the flux linkage by a pre-generated low-pass filter; A saturation criterion of the flexible DC converter transformer is generated according to the DC component to suppress the DC bias of the flux linkage of the flexible DC converter transformer.

2. The method for suppressing magnetic flux saturation under the combined surge current according to claim 1, characterized in that: Generating a saturation criterion of the flexible DC converter transformer according to the DC component includes: Normalizing the DC component to generate a per-unit value of the DC component; The saturation criterion is generated according to the per-unit value.

3. The method for suppressing magnetic flux saturation under the combined inrush current according to claim 1, characterized in that: The grid-side electrical characteristic parameters include: grid-side current, grid-side voltage, grid-side leakage resistance, grid-side leakage reactance and residual magnetism.

4. The method for suppressing magnetic flux saturation under a reactive surge current according to any one of claims 1 to 3, characterized in that: The step of suppressing the flux DC bias of the flexible DC converter transformer comprises: generating an enable signal for a flux linkage DC bias suppressor according to the saturation criterion; The flux DC bias of the flexible DC converter transformer is suppressed according to the enable signal.

5. The method for suppressing magnetic flux saturation under the combined surge current according to claim 4, characterized in that: Also includes: The output voltage of the feedback loop of the flux DC bias suppressor is determined according to the DC component, the proportional coefficient and the integral coefficient of the flux controller.

6. A flexible DC converter transformer and a device for suppressing flux saturation under inrush current, characterized in that: include: A flux linkage determination module, used to determine the flux linkage of the flexible DC converter transformer according to the grid-side electrical characteristic parameters of the flexible DC converter transformer; A DC component extraction module, used to extract the DC component of the flux linkage through a pre-generated low-pass filter; The flux DC bias suppression module is used to generate a saturation criterion of the flexible DC converter transformer according to the DC component to suppress the flux DC bias of the flexible DC converter transformer.

7. The device for suppressing magnetic flux saturation under the combined surge flow according to claim 6, characterized in that: The flux linkage DC bias suppression module comprises: a per-unit value generating unit, used for normalizing the DC component to generate a per-unit value of the DC component; A saturation criterion generating unit is used to generate the saturation criterion according to the per-unit value.

8. The device for suppressing magnetic flux saturation under the combined surge flow according to claim 6, characterized in that: The grid-side electrical characteristic parameters include: grid-side current, grid-side voltage, grid-side leakage resistance, grid-side leakage reactance and residual magnetism.

9. The device for suppressing magnetic flux saturation under a responsive surge flow according to any one of claims 6 to 7, characterized in that: The flux linkage DC bias suppression module also includes: An enable signal generating unit, used for generating an enable signal of a flux linkage DC bias suppressor according to the saturation criterion; A flux DC bias suppression unit is used to suppress the flux DC bias of the flexible DC converter transformer according to the enable signal.

10. The device for suppressing magnetic flux saturation under the combined surge flow according to claim 9, characterized in that: Also includes: The output voltage determination module is used to determine the output voltage of the feedback loop of the flux DC bias suppressor according to the DC component, the proportional coefficient and the integral coefficient of the flux controller.

11. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the steps of the flexible DC converter transformer and the method for suppressing flux saturation under inrush current described in any one of claims 1 to 5 are implemented.

12. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the flexible DC converter transformer and the method for suppressing flux saturation under inrush current described in any one of claims 1 to 5 are implemented.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the flexible DC converter transformer and the method for suppressing flux saturation under inrush current described in any one of claims 1 to 5 are implemented.

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