A method and device for simulating transformer saturation state
By calculating the saturation reactance and biased flux unit of the transformer and setting the flux bias parameters in the simulation model, the accurate simulation of the saturation state of the transformer is achieved, and the problem of difficulty in simulation reproduction in the existing technology is solved.
Patent Information
- Application Number
- CN202210687990.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-06-17
- Publication Date
- 2025-03-18
- Estimated Expiration
- 2042-06-17
AI Technical Summary
The existing transformer saturation state simulation work has the problem of difficulty in reproducing simulation, especially because the harmonic components are complex and the degree of saturation are difficult to determine, resulting in large errors in the simulation results and on-site actual situation.
By obtaining the maximum excitation inrush current data of the target transformer, calculating its saturation reactance, and combining the peak current value of the neutral point of the Y-connection winding and the inflection point voltage of the core magnetization curve, the unity of the biased magnetic flux is calculated. Then, the flux bias parameters of the transformer excitation branch are set in the simulation model to realize the simulation of the transformer saturation state.
Through this method, the harmonic resonance phenomenon caused by transformer saturation can be more accurately simulated, solve the problem of difficulty in simulation reproduction, and improve the accuracy of simulation results.
Smart Images
Figure CN115062472B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of transformer simulation, and in particular to a method and device for simulating a transformer saturation state. Background Art
[0002] The resonance or harmonic phenomenon caused by transformer saturation due to various factors is common in power systems, and its simulation and reproduction is also a difficulty in analyzing such accidents. Typical harmonics caused by transformer saturation often have complex harmonic components and the degree of saturation is difficult to determine, which makes the simulation of transformer saturation state difficult to reproduce. Summary of the invention
[0003] The present application provides a transformer saturation state simulation method and device, which are used to solve the technical problem of difficulty in simulation reproduction in existing transformer saturation state simulation work.
[0004] In order to solve the above technical problems, the first aspect of the present application provides a transformer saturation state simulation method, comprising:
[0005] Obtain the maximum excitation inrush current data of the target transformer;
[0006] Based on the maximum excitation inrush current data and in combination with a saturation reactance calculation formula, the saturation reactance of the target transformer is calculated;
[0007] According to the saturated reactance, combined with the peak value of the neutral point current of the Y-connected winding of the target transformer and the inflection point voltage of the iron core magnetization curve of the target transformer, the bias magnetic flux per unit value of the target transformer is converted;
[0008] According to the calculated bias flux per unit value, the flux bias parameter of the transformer excitation branch is set in the simulation model, so as to simulate the transformer saturation state of the target transformer according to the flux bias parameter.
[0009] Preferably, the saturation reactance calculation formula is specifically:
[0010]
[0011] Where U j is the system voltage rating, I max is the maximum excitation inrush current, X air is the saturated reactance.
[0012] Preferably, when the target transformer is empty-charged from the high-voltage side or both sides are connected to the power grid, the system voltage rating is equal to the high-voltage side power grid voltage rating; when the target transformer is empty-charged from the low-voltage side, the system voltage rating is equal to the low-voltage side power grid voltage rating.
[0013] Preferably, the converting the bias flux per unit value of the target transformer according to the saturated reactance, in combination with the neutral point current peak value of the Y-connected winding of the target transformer and the inflection point voltage of the core magnetization curve of the target transformer specifically includes:
[0014] Based on the saturated reactance, calculating a saturated reactance per unit value corresponding to the saturated reactance;
[0015] Based on the saturated reactance per unit value, combined with the UI relationship curve of the excitation current and the peak value of the neutral point current of the Y-connected winding, the voltage per unit value corresponding to the bias magnetic flux of the target transformer is calculated;
[0016] A bias flux per unit value is determined based on the voltage per unit value.
[0017] Preferably, the calculation formula of the bias magnetic flux per unit value is specifically:
[0018] φ1=U1
[0019]
[0020] Where, φ1 is the bias flux per unit value, U1 is the voltage per unit value, X * is the per-unit value of the saturated reactance, and I0 is the peak value of the neutral point current of the Y-connected winding.
[0021] At the same time, the second aspect of the present application also provides a transformer saturation state simulation device, including:
[0022] An excitation inrush current data acquisition unit, used to acquire maximum excitation inrush current data of a target transformer;
[0023] A saturated reactance calculation unit, configured to calculate the saturated reactance of the target transformer based on the maximum excitation inrush current data and in combination with a saturated reactance calculation formula;
[0024] A transformer saturation degree conversion unit, used to convert the bias magnetic flux per unit value of the target transformer according to the saturation reactance, in combination with the peak value of the neutral point current of the Y-connected winding of the target transformer and the inflection point voltage of the iron core magnetization curve of the target transformer;
[0025] The saturation simulation configuration unit is used to set the flux bias parameter of the transformer excitation branch in the simulation model according to the converted bias flux per unit value, so as to simulate the transformer saturation state of the target transformer according to the flux bias parameter.
[0026] Preferably, the saturation reactance calculation formula is specifically:
[0027]
[0028] Where U j is the system voltage rating, I max is the maximum excitation inrush current, X air is the saturated reactance.
[0029] Preferably, when the target transformer is empty-charged from the high-voltage side or both sides are connected to the power grid, the system voltage rating is equal to the high-voltage side power grid voltage rating; when the target transformer is empty-charged from the low-voltage side, the system voltage rating is equal to the low-voltage side power grid voltage rating.
[0030] Preferably, the transformer saturation degree conversion unit is specifically used for:
[0031] Based on the saturated reactance, calculating a saturated reactance per unit value corresponding to the saturated reactance;
[0032] Based on the saturated reactance per unit value, combined with the UI relationship curve of the excitation current and the peak value of the neutral point current of the Y-connected winding, the voltage per unit value corresponding to the bias magnetic flux of the target transformer is calculated;
[0033] A bias flux per unit value is determined based on the voltage per unit value.
[0034] Preferably, the calculation formula of the bias magnetic flux per unit value is specifically:
[0035] φ1=U1
[0036]
[0037] Where, φ1 is the bias flux per unit value, U1 is the voltage per unit value, X * is the per-unit value of the saturated reactance, and I0 is the peak value of the neutral point current of the Y-connected winding.
[0038] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:
[0039] This application is based on the characteristic that core saturation usually produces periodic peak current at the neutral point of the Y-connected winding of the transformer. According to the calculated saturation reactance, combined with the peak current of the neutral point of the Y-connected winding of the target transformer and the inflection point voltage of the core magnetization curve of the target transformer, the bias flux per unit value of the target transformer is converted. According to the converted bias flux per unit value, the flux bias parameters of the transformer excitation branch are set in the simulation model to realize the simulation of the transformer saturation state of the target transformer. The scheme of this application can more accurately simulate the harmonic resonance phenomenon caused by transformer saturation on site, and solves the technical problem of difficult simulation reproduction in the existing transformer saturation state simulation work. BRIEF DESCRIPTION OF THE DRAWINGS
[0040] In order to more clearly illustrate the embodiments of the present application 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 only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0041] Figure 1 A schematic flow chart of an embodiment of a transformer saturation state simulation method provided in the present application.
[0042] Figure 2 This is the transformer magnetization curve.
[0043] Figure 3 A schematic structural diagram of an embodiment of a transformer saturation state simulation device provided in the present application. DETAILED DESCRIPTION
[0044] Existing electromagnetic transient simulation models often ignore the phenomenon of transformer core saturation. The modeling refers to the electromechanical transient model and can only reflect the power frequency characteristics of the transformer. Some models that have considered transformer core saturation lack relevant information on the degree of core saturation when reproducing on-site phenomena, and cannot accurately simulate the harmonic resonance phenomenon on site. The simulation results have a large error with the actual on-site situation. The resonance or harmonic phenomenon caused by transformer saturation due to various factors is relatively common in power systems, and its simulation and reproduction is also a difficulty in analyzing such accidents. Typical harmonics caused by transformer saturation often have complex harmonic components, difficult to determine the degree of saturation, and difficult simulation and reproduction.
[0045] However, the applicant has found through research that transformer core saturation also has relatively obvious characteristics, that is, core saturation usually produces periodic peak current at the neutral point of the transformer Y-connected winding. The harmonics caused by transformer core saturation can be simulated based on this characteristic.
[0046] In view of this, an embodiment of the present application provides a transformer saturation state simulation method and device, which are used to solve the technical problem of difficulty in simulation reproduction in existing transformer saturation state simulation work.
[0047] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the embodiments described below are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0048] See also Figure 1The first embodiment of the present application provides a transformer saturation state simulation method, comprising:
[0049] Step 101: Acquire maximum excitation inrush current data of a target transformer.
[0050] Step 102: Calculate the saturated reactance of the target transformer based on the maximum excitation inrush current data and the saturated reactance calculation formula.
[0051] It should be noted that the transformer saturation reactance X is calculated based on the maximum excitation inrush current. air In this step, the maximum excitation inrush current I is obtained based on field measurements and operating experience. max . Calculate the saturated reactance according to the formula:
[0052]
[0053] Where U j is the system voltage rating, I max is the maximum excitation inrush current, X air is the saturated reactance.
[0054] Among them, the system voltage rating U j If the transformer is charged from the high-voltage side, the voltage is the rated value of the high-voltage side grid voltage; if the transformer is charged from the low-voltage side, the voltage is the rated value of the low-voltage side grid voltage; if both sides of the transformer are connected to the grid, the voltage is the rated value of the high-voltage side grid voltage.
[0055] Step 103: Calculate the per unit value of the bias flux of the target transformer according to the saturated reactance, in combination with the peak value of the neutral point current of the Y-connected winding of the target transformer and the inflection point voltage of the core magnetization curve of the target transformer.
[0056] More specifically, the process of step 103 specifically includes:
[0057] Based on the saturated reactance, calculate the saturated reactance per unit value corresponding to the saturated reactance;
[0058] Based on the per-unit value of saturated reactance, combined with the UI relationship curve of excitation current and the peak value of neutral point current of Y-connected winding, the per-unit voltage value corresponding to the bias magnetic flux of the target transformer is calculated;
[0059] The bias flux per unit value is determined based on the voltage per unit value.
[0060] Next, the transformer saturation degree is calculated based on the peak value of the neutral point current of the Y-connected winding of the transformer, the saturation reactance value, and the inflection point of the magnetization curve (also known as the BH curve). The simplified transformer core magnetization curve is shown as the abc line in the figure below. Since the excitation current of the transformer is very small during normal operation, usually not more than 2A, it is negligible compared to the neutral point current when the transformer is saturated. The magnetization curve can be approximately considered as follows: Figure 2 As shown by straight line bc.
[0061] When the magnetic field strength is below the rated value, the magnetic induction intensity B is linearly related to the magnetic field intensity H, as shown in the abc segment. After H continues to increase to the inflection point b, the rate at which the magnetic induction intensity B increases with H will significantly slow down, as shown in the bc segment. The magnetic field intensity H is proportional to the excitation current i, as shown in the following formula:
[0062] Hl=Ni
[0063] Where l is the length of the magnetic circuit and N is the number of turns.
[0064] For AC sinusoidal analysis, the relationship between the induced electromotive force or voltage E and the magnetic flux φ is:
[0065]
[0066] In the formula, φ m The flux amplitude, f is the grid frequency.
[0067] The relationship between magnetic flux φ and magnetic induction intensity B is:
[0068] φ=BA
[0069] Where B is the magnetic induction intensity and A is the cross-sectional area of the magnetic material.
[0070] Therefore, the UI curve relationship between voltage and excitation current can correspond to the magnetization curve one by one. If both are expressed in per unit value, the curves should be consistent. The UI curve above the inflection point can be expressed as:
[0071]
[0072]
[0073]
[0074] Where U0 is the inflection point voltage, X * is the per unit value of the saturated reactance, X j is the reference reactance, U j is the system voltage rating, S j The base capacity.
[0075] Taking the measured peak value I0 of the neutral point current of the Y-connected transformer winding, the voltage per unit value U1 corresponding to the bias magnetic flux is:
[0076]
[0077] The per-unit value of the bias magnetic flux φ1 is:
[0078] φ1=U1
[0079] Step 104: according to the calculated bias flux per unit value, the flux bias parameter of the transformer excitation branch is set in the simulation model, so as to simulate the transformer saturation state of the target transformer according to the flux bias parameter.
[0080] Next, the transformer core flux bias parameters in the simulation model are set according to the converted transformer saturation degree. In this step, the flux bias parameters of the transformer excitation branch are set in the simulation model to simulate the transformer saturation state of the target transformer according to the flux bias parameters. Taking a sine wave as an example, its flux is expressed as:
[0081] φ(t)=φ1+φ m sin(ωt+θ0)
[0082] In the formula, φ m is the magnetic flux amplitude, θ0 is the initial phase angle.
[0083] The above content is a detailed description of an embodiment of a transformer saturation state simulation method provided by the present application. The following is a detailed description of an embodiment of a transformer saturation state simulation device provided by the present application.
[0084] See also Figure 3 The second embodiment of the present application further provides a transformer saturation state simulation device, comprising:
[0085] An excitation inrush current data acquisition unit 201, used to acquire maximum excitation inrush current data of a target transformer;
[0086] A saturated reactance calculation unit 202 is used to calculate the saturated reactance of the target transformer based on the maximum excitation inrush current data and the saturated reactance calculation formula;
[0087] The transformer saturation degree conversion unit 203 is used to convert the bias magnetic flux per unit value of the target transformer according to the saturation reactance, combined with the peak value of the neutral point current of the Y-connected winding of the target transformer and the inflection point voltage of the iron core magnetization curve of the target transformer;
[0088] The saturation simulation configuration unit 204 is used to set the flux bias parameter of the transformer excitation branch in the simulation model according to the converted bias flux per unit value, so as to simulate the transformer saturation state of the target transformer according to the flux bias parameter.
[0089] Furthermore, the saturation reactance calculation formula is as follows:
[0090]
[0091] Where U j is the system voltage rating, I max is the maximum excitation inrush current, X air is the saturated reactance.
[0092] Furthermore, when the target transformer is empty-charged from the high-voltage side or both sides are connected to the grid, the system voltage rating is equal to the high-voltage side grid voltage rating; when the target transformer is empty-charged from the low-voltage side, the system voltage rating is equal to the low-voltage side grid voltage rating.
[0093] Furthermore, the transformer saturation degree conversion unit 203 is specifically used for:
[0094] Based on the saturated reactance, calculate the saturated reactance per unit value corresponding to the saturated reactance;
[0095] Based on the per-unit value of saturated reactance, combined with the UI relationship curve of excitation current and the peak value of neutral point current of Y-connected winding, the per-unit voltage value corresponding to the bias magnetic flux of the target transformer is calculated;
[0096] The bias flux per unit value is determined based on the voltage per unit value.
[0097] Furthermore, the calculation formula of the bias magnetic flux per unit value is specifically:
[0098] φ1=U1
[0099]
[0100] In the formula, φ1 is the bias flux per unit value, U1 is the voltage per unit value, X * is the per unit value of saturated reactance, and I0 is the peak current of the neutral point of the Y-connected winding.
[0101] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the terminals, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.
[0102] In the several embodiments provided in the present application, it should be understood that the disclosed terminals, devices and methods can be implemented in other ways. For example, 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, 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.
[0103] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0104] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
[0105] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.
[0106] 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 is essentially 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, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.
[0107] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. 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 application.
Claims
1. A transformer saturation state simulation method, characterized in that: include: Obtain the maximum excitation inrush current data of the target transformer; Based on the maximum excitation inrush current data and in combination with a saturation reactance calculation formula, the saturation reactance of the target transformer is calculated; Based on the saturated reactance, calculating a saturated reactance per unit value corresponding to the saturated reactance; Based on the saturated reactance per unit value, combined with the UI relationship curve of the excitation current and the peak value of the neutral point current of the Y-connected winding, the voltage per unit value corresponding to the bias magnetic flux of the target transformer is calculated; The bias magnetic flux per unit value is determined based on the voltage per unit value, wherein the calculation formula of the bias magnetic flux per unit value is specifically: φ1=U1 Where, φ1 is the bias flux per unit value, U1 is the voltage per unit value, X * is the per-unit value of the saturated reactance, and I0 is the peak value of the neutral point current of the Y-connected winding; According to the calculated bias flux per unit value, the flux bias parameter of the transformer excitation branch is set in the simulation model, so as to simulate the transformer saturation state of the target transformer according to the flux bias parameter.
2. A transformer saturation state simulation method according to claim 1, characterized in that: The saturation reactance calculation formula is specifically: Where U j is the system voltage rating, I max is the maximum excitation inrush current, X air is the saturated reactance.
3. A transformer saturation state simulation method according to claim 2, characterized in that: When the target transformer is empty-charged from the high-voltage side or both sides are connected to the power grid, the system voltage rating is equal to the high-voltage side power grid voltage rating; when the target transformer is empty-charged from the low-voltage side, the system voltage rating is equal to the low-voltage side power grid voltage rating.
4. A transformer saturation state simulation device, characterized in that: include: An excitation inrush current data acquisition unit, used to acquire maximum excitation inrush current data of a target transformer; A saturated reactance calculation unit, configured to calculate the saturated reactance of the target transformer based on the maximum excitation inrush current data and in combination with a saturated reactance calculation formula; The transformer saturation degree conversion unit is used to calculate the saturation reactance per unit value corresponding to the saturation reactance based on the saturation reactance, calculate the voltage per unit value corresponding to the bias magnetic flux of the target transformer based on the saturation reactance per unit value, combined with the UI relationship curve of the excitation current and the peak value of the neutral point current of the Y-connected winding, and determine the bias magnetic flux per unit value based on the voltage per unit value, wherein the calculation formula of the bias magnetic flux per unit value is specifically: φ1=U1 Where, φ1 is the bias flux per unit value, U1 is the voltage per unit value, X * is the per-unit value of the saturated reactance, and I0 is the peak value of the neutral point current of the Y-connected winding; The saturation simulation configuration unit is used to set the flux bias parameter of the transformer excitation branch in the simulation model according to the converted bias flux per unit value, so as to simulate the transformer saturation state of the target transformer according to the flux bias parameter.
5. A transformer saturation state simulation device according to claim 4, characterized in that: The saturation reactance calculation formula is specifically: Where U j is the system voltage rating, I max is the maximum excitation inrush current, X air is the saturated reactance.
6. A transformer saturation state simulation device according to claim 4, characterized in that: When the target transformer is empty-charged from the high-voltage side or both sides are connected to the grid, the system voltage rating is equal to the high-voltage side grid voltage rating; when the target transformer is empty-charged from the low-voltage side, the system voltage rating is equal to the low-voltage side grid voltage rating.