A capacity determination method, system, medium and device of a double-reflex star type transformer
By obtaining the load loss and effective value of harmonic current of the reference transformer, the set of harmonic coefficients is determined and the capacity calculation is corrected, thus solving the loss problem caused by harmonic current in the design of double-reverse star transformers and ensuring the reliability and lifespan of the transformer under harmonic conditions.
Patent Information
- Application Number
- CN202611139913.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-30
- Publication Date
- 2026-08-25
AI Technical Summary
The existing double-reverse star transformer design does not fully consider the losses and temperature rise caused by harmonic currents, resulting in temperature rise exceeding expectations during actual operation, which poses risks of abnormal heating, shortened lifespan, or even burnout.
By obtaining the load loss and effective value of harmonic current of a reference transformer under harmonic conditions, the set of harmonic coefficients is determined, and the traditional capacity calculation formula is corrected based on the capacity expansion coefficient to ensure the rationality of the transformer capacity design under harmonic conditions.
This enables reliable operation of the transformer under harmonic conditions, avoids excessive temperature rise, extends service life, and reduces the risk of equipment burnout.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of transformer design technology, and in particular to a method, system, medium, and equipment for determining the capacity of a double-reverse star transformer. Background Technology
[0002] A double-reverse star-type rectifier transformer, together with two sets of three-phase half-wave rectifiers, constitutes a rectifier power supply, widely used in low-voltage, high-current DC power applications such as water electrolysis and metal plating. This rectifier power supply has a simple circuit structure and low cost, but it contains a large amount of harmonic current that causes abnormal transformer heating, posing a challenge to the transformer's product stability. Currently, in the design phase of double-reverse star-type transformers, only the transformer capacity under fundamental wave conditions is typically considered. However, in actual operation, due to uncontrollable factors such as asymmetry in the firing angles of the positive and negative half-shafts of the rectifier, differences in voltage drops of rectifier devices, and asymmetry in phase-to-phase impedance, the harmonic current content increases significantly. In particular, the actual harmonic spectrum after superimposing even-order harmonics is much higher than the odd-order harmonic level under ideal 6-pulse rectification. This leads to a significant increase in transformer losses, and the actual temperature rise of the transformer far exceeds design expectations.
[0003] However, the losses and temperature rise caused by harmonic currents have not been fully considered in the current design phase, resulting in transformers designed according to traditional capacity experiencing higher-than-expected temperature rises during actual operation, posing risks of abnormal heating, shortened lifespan, or even burnout.
[0004] Therefore, there is an urgent need to provide a method for determining the capacity of a double-reverse star transformer that can take into account the load loss of the transformer under harmonic conditions, thereby reasonably determining the transformer capacity and ensuring the reliability of the transformer operation under harmonic conditions. Summary of the Invention
[0005] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method, system, medium and equipment for determining the capacity of a double-reverse star transformer, which can accurately calculate the losses caused by harmonics based on the actual harmonic conditions on site, thereby reasonably determining the transformer capacity and ensuring the reliability of transformer operation under harmonic conditions.
[0006] This invention is implemented according to the following scheme: A method for determining the capacity of a double-reverse star-connected transformer is provided, including: Obtain the load loss set of the reference transformer under the fundamental operating condition of the transformer to be designed, and the effective value of each harmonic current of the reference transformer under the harmonic operating condition of the transformer to be designed. Based on the effective values of each harmonic current and the set of load losses, determine the set of harmonic coefficients of the reference transformer under the harmonic operating conditions of the transformer to be designed. Based on the load loss set and the harmonic coefficient set, a capacity expansion factor is determined to quantify the impact of the harmonic operating condition on the capacity of the reference transformer. The capacity of the transformer to be designed is determined based on the capacity expansion factor.
[0007] Optionally, the load loss set includes DC loss, eddy current loss, and stray loss; Obtain the set of load losses of the reference transformer under the fundamental operating conditions of the transformer to be designed, including: A load loss test was performed on the reference transformer under rated load and a first frequency to obtain the first load loss; A load loss test was performed on the reference transformer at rated load and a second frequency to obtain the second load loss. A load loss test was performed on the reference transformer at rated load and third frequency to obtain the third load loss. The DC loss, the eddy current loss, and the stray loss are obtained based on the first load loss, the second load loss, and the third load loss.
[0008] Optionally, the load loss set includes the eddy current loss of the reference transformer under the fundamental operating condition; Based on the effective values of each harmonic current and the set of load losses, the set of harmonic coefficients of the reference transformer under the harmonic operating conditions of the transformer to be designed is determined, including: The effective value of the fundamental current of the reference transformer under the fundamental operating condition, the harmonic order under the harmonic operating condition, and the winding eddy current loss of the reference transformer under the fundamental operating condition and when the leakage magnetic field shape meets the preset requirements are obtained. The set of harmonic coefficients is determined based on the effective values of each harmonic current, the eddy current loss of the reference transformer under the fundamental operating condition, the effective value of the fundamental current, the harmonic order, and the winding eddy current loss.
[0009] Optionally, the set of harmonic coefficients includes the effective value coefficient of non-sinusoidal line current, the harmonic coefficient of eddy current loss, and the harmonic coefficient of stray loss. Based on the effective values of each harmonic current, the eddy current loss of the reference transformer under the fundamental operating condition, the effective value of the fundamental current, the harmonic order, and the winding eddy current loss, the set of harmonic coefficients is determined, including: The effective value coefficient of the non-sinusoidal line current is determined based on the effective values of each harmonic current. The eddy current loss harmonic coefficient is determined based on the effective values of each harmonic current, the effective value of the fundamental current, the eddy current loss of the reference transformer under the fundamental operating condition, the harmonic order, and the winding eddy current loss. The stray loss harmonic coefficient is determined based on the effective values of each harmonic current, the effective value of the fundamental current, the eddy current loss of the reference transformer under the fundamental operating condition, and the harmonic order.
[0010] Optionally, based on the load loss set and the harmonic coefficient set, a capacity expansion factor is determined to quantify the impact of the harmonic operating condition on the reference transformer capacity, including: Obtain the effective value of the fundamental current of the reference transformer under fundamental operating conditions; The DC equivalent resistance is determined based on the effective value of the fundamental current and the set of load losses. The capacitance factor is determined based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance.
[0011] Optionally, the capacitance factor is determined based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance, including: Based on the load loss set, determine the fundamental load loss of the reference transformer under the fundamental operating condition; Based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance, the harmonic load loss of the reference transformer under the harmonic operating condition is determined. The capacity expansion factor is determined based on the fundamental load loss and the harmonic load loss.
[0012] Optionally, determining the capacity of the transformer to be designed based on the capacity expansion factor includes: Obtain the valve-side rated DC voltage and valve-side rated DC current of the transformer to be designed; The capacity of the transformer to be designed is determined based on the capacity expansion factor, the rated DC voltage on the valve side, and the rated DC current on the valve side.
[0013] A capacity determination system for a double-reverse star transformer is also provided, applied to the aforementioned capacity determination method for a double-reverse star transformer, comprising: The data acquisition module is used to acquire the load loss set of the reference transformer under the fundamental operating condition of the transformer under design, and the effective value of each harmonic current of the reference transformer under the harmonic operating condition of the transformer under design. The data processing module is used for: Based on the effective values of each harmonic current and the set of load losses, determine the set of harmonic coefficients of the reference transformer under the harmonic operating conditions of the transformer to be designed. Based on the load loss set and the harmonic coefficient set, a capacity expansion factor is determined to quantify the impact of the harmonic operating condition on the capacity of the reference transformer. The capacity determination module is used to determine the capacity of the transformer to be designed based on the capacity expansion factor.
[0014] A computer-readable storage medium is also provided, which is a computer-readable storage medium storing a computer program thereon, which, when executed, implements the method for determining the capacity of a double-reverse star transformer.
[0015] A computer device is also provided, including a processor and a memory, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and the processor loads and executes the at least one instruction, at least one program, code set or instruction set to implement the method for determining the capacity of a double anti-star transformer.
[0016] Compared with the prior art, the beneficial effects of the capacity determination method of the double-reverse star transformer of the present invention are as follows: By obtaining the load loss set of the reference transformer under the harmonic operating conditions of the transformer to be designed, the capacity expansion factor used to indicate the increase multiple of the required capacity of the reference transformer under harmonic operating conditions relative to the fundamental operating conditions is determined. This quantifies the impact of the actual harmonic operating conditions on the transformer loss as the capacity expansion factor, and the capacity of the transformer to be designed is determined based on the capacity expansion factor. This allows the transformer capacity to truly reflect the additional losses and temperature rise requirements brought about by harmonics, avoiding the problem of excessive temperature rise during actual operation caused by designing only according to the fundamental operating conditions in the traditional method. This ensures that the transformer can still operate reliably under actual operating conditions containing harmonics, effectively extending the service life of the transformer and reducing the risk of equipment burnout. Attached Figure Description
[0017] Figure 1 This is the circuit wiring diagram for a double-reverse star transformer. Figure 2 This is a flowchart of the capacity determination method of the present invention. Detailed Implementation
[0018] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0019] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of this application.
[0020] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0021] See Figure 1 The diagram shows the circuit wiring principle of a double-reverse star transformer. The high-voltage side of the double-reverse star transformer is star-connected, with the high-voltage windings of each phase connected in parallel, namely HVA upper, HVA lower, HVB upper, HVB lower, HVC upper, and HVC lower. The low-voltage side of the double-reverse star transformer has two star-connected windings, namely LVA upper, LVA lower, LVb upper, LVb lower, LVc upper, and LVc lower. On the low-voltage side of the double-reverse star transformer, the upper and lower windings are 180° out of phase and are connected to two three-phase half-wave rectifier circuits respectively, and are connected in parallel through a balancing reactor to output a 6-pulse voltage waveform.
[0022] See Figure 2 As shown, the present invention provides a method for determining the capacity of a double-reverse star-type transformer, comprising: S1: Obtain the load loss set of the reference transformer under the fundamental operating condition of the transformer to be designed, and the effective value of each harmonic current of the reference transformer under the harmonic operating condition of the transformer to be designed; wherein, the fundamental operating condition is used to indicate the ideal state of the transformer operating under pure sinusoidal current, and the harmonic operating condition is used to indicate the non-sinusoidal operating state of the transformer under actual rectified load containing each harmonic current.
[0023] In practical applications, the same transformer operates under different fundamental or harmonic conditions, resulting in different load loss sets and effective values of each harmonic current. Therefore, in this invention, the fundamental and harmonic conditions are determined based on the operating scenario of the transformer after production, to ensure that the obtained data matches the actual operating conditions of the transformer.
[0024] In the actual operation of a double-reverse star transformer, if the double-reverse star transformer is in the fundamental frequency condition, the transformer will not generate additional losses caused by harmonics. However, if the double-reverse star transformer is in the harmonic condition, the transformer will operate with each harmonic current superimposed on the fundamental frequency current, which will lead to additional losses caused by harmonics. At this time, the actual heat generation of the transformer far exceeds the design expectation under the fundamental frequency condition, which will cause the transformer temperature rise to exceed the limit, shorten its lifespan, or even burn out.
[0025] This invention uses a commercially available reference transformer as a design benchmark during the design phase of the transformer to be designed. By using the reference transformer, the design benchmark can be used to understand the loss characteristics of the transformer to be designed under actual fundamental wave conditions and the harmonic current distribution under actual harmonic wave conditions when the transformer to be designed is manufactured.
[0026] In one embodiment of the present invention, the load loss set includes the DC loss, eddy current loss, and stray loss of a reference transformer under fundamental operating conditions; obtaining the load loss set of the reference transformer under the fundamental operating conditions of the transformer to be designed includes: performing a load loss test on the reference transformer under rated load and a first frequency to obtain a first load loss; performing a load loss test on the reference transformer under rated load and a second frequency to obtain a second load loss; performing a load loss test on the reference transformer under rated load and a third frequency to obtain a third load loss; and obtaining the DC loss, eddy current loss, and stray loss based on the first load loss, the second load loss, and the third load loss.
[0027] In practical applications, the DC loss of a double-reverse star transformer is independent of frequency, the eddy current loss is proportional to the square of the frequency, and the stray loss is proportional to the 0.8th power of the frequency. Through load loss tests at three different frequencies, the proportions of DC loss, eddy current loss, and stray loss in the load loss can be calculated. Among them, the first load loss, the second load loss, and the third load loss are the load losses of the reference transformer at three different frequencies under the fundamental frequency condition.
[0028] In one embodiment of the present invention, with a reference frequency as the first frequency, the expression for the first load loss is as follows:
[0029] in, For the first load loss, For the first frequency, The DC resistance of the winding. The DC resistance of the connecting wire. DC loss, For eddy current losses, For stray loss, This refers to the eddy current loss in the connecting line. For stray losses of structural components, The reference transformer is defined as the effective value of the fundamental current at its rated current, specifically the root mean square value of the fundamental current at its rated current.
[0030] The expression for the second load loss is as follows:
[0031] in, For the second load loss, For the first frequency, For the second frequency, The DC resistance of the winding. The DC resistance of the connecting wire. DC loss, For eddy current losses, For stray loss, This refers to the eddy current loss in the connecting line. For stray losses of structural components, The reference transformer is defined as the effective value of the fundamental current at its rated current, specifically the root mean square value of the fundamental current at its rated current.
[0032] The expression for the second load loss is as follows:
[0033] in, The third load loss, For the first frequency, The third frequency, The DC resistance of the winding. The DC resistance of the connecting wire. DC loss, For eddy current losses, For stray loss, This refers to the eddy current loss in the connecting wire. For stray losses of structural components, The reference transformer is defined as the effective value of the fundamental current at its rated current, specifically the root mean square value of the fundamental current at its rated current.
[0034] By substituting the specific values of the first load loss, the second load loss, and the third load loss into the corresponding expressions mentioned above, the DC loss, eddy current loss, and stray loss of the reference transformer under the fundamental operating condition can be determined.
[0035] S2: Based on the effective values of each harmonic current and the set of load losses, determine the set of harmonic coefficients of the reference transformer under the harmonic operating conditions of the transformer to be designed, including: obtaining the effective value of the fundamental current of the reference transformer under the fundamental operating conditions, the harmonic order under the harmonic operating conditions, and the winding eddy current loss of the reference transformer under the fundamental operating conditions and when the leakage magnetic field shape meets the preset requirements; determine the set of harmonic coefficients based on the effective values of each harmonic current, the eddy current loss of the reference transformer under the fundamental operating conditions, the effective value of the fundamental current, the harmonic order, and the winding eddy current loss.
[0036] In one embodiment of the present invention, the harmonic coefficient set includes the effective value coefficient of the non-sinusoidal line current, the eddy current loss harmonic coefficient, and the stray loss harmonic coefficient. The harmonic coefficient set is determined based on the effective values of each harmonic current, the eddy current loss of the reference transformer under fundamental operating conditions, the effective value of the fundamental current, the harmonic order, and the winding eddy current loss. This includes: determining the effective value coefficient of the non-sinusoidal line current based on the effective values of each harmonic current; determining the eddy current loss harmonic coefficient based on the effective values of each harmonic current, the effective value of the fundamental current, the eddy current loss of the reference transformer under fundamental operating conditions, the harmonic order, and the winding eddy current loss; and determining the stray loss harmonic coefficient based on the effective values of each harmonic current, the effective value of the fundamental current, the eddy current loss of the reference transformer under fundamental operating conditions, and the harmonic order.
[0037] In one embodiment of the present invention, determining the effective value coefficient of the non-sinusoidal line current based on the effective values of each harmonic current and the fundamental current includes: determining the effective value of the non-sinusoidal line current based on the effective values of each harmonic current; and determining the effective value coefficient of the non-sinusoidal line current based on the effective value of the non-sinusoidal line current, specifically using the root mean square value of the effective value of the non-sinusoidal line current as the effective value coefficient. This part is described in standard number GB / T 18494.1-2014, Chinese standard name: Converter Transformers Part 1: Industrial Converter Transformers; wherein, the expression for the effective value of the non-sinusoidal line current is as follows:
[0038] in, This is the effective value of the non-sinusoidal line current. This is the effective value of the h-th harmonic current.
[0039] In one embodiment of the present invention, the expression for the eddy current loss harmonic coefficient is determined based on the effective values of each harmonic current, the effective value of the fundamental current, the eddy current loss of the reference transformer under fundamental operating conditions, the harmonic order, and the winding eddy current loss:
[0040] in, The harmonic coefficient represents the eddy current loss. The effective value of the h-th harmonic current. This is the effective value of the fundamental current. To reference the eddy current loss of the transformer under fundamental operating conditions, For harmonic order, To determine the winding eddy current loss of a reference transformer under fundamental frequency conditions and with a leakage magnetic field shape that meets preset requirements, the leakage magnetic field shape meets preset requirements specifically means that the leakage magnetic field shape of the reference transformer under fundamental frequency conditions is similar to its leakage magnetic field shape under harmonic frequency conditions. Specifically, a similarity threshold can be set. When the similarity between the leakage magnetic field shape of the reference transformer under fundamental frequency conditions and its leakage magnetic field shape under harmonic frequency conditions reaches this similarity threshold, the leakage magnetic field shape meets the preset requirements.
[0041] In one embodiment of the present invention, the expression for the stray loss harmonic coefficient is determined based on the effective values of each harmonic current, the effective value of the fundamental current, the eddy current loss of the reference transformer under fundamental operating conditions, and the harmonic order, as follows:
[0042] in, This is an additional coefficient for eddy current loss in the connecting line. Additional coefficients for stray losses in structural components and eddy current losses in connecting lines. and additional coefficient for stray losses of structural components They are equal, both being stray loss harmonic coefficients. The effective value of the h-th harmonic current. This is the effective value of the fundamental current. To reference the eddy current loss of the transformer under fundamental operating conditions, This represents the harmonic order.
[0043] S3: Based on the load loss set and the harmonic coefficient set, determine the capacity expansion factor used to quantify the impact of harmonic operating conditions on the reference transformer capacity, including: obtaining the effective value of the fundamental current of the reference transformer under the fundamental operating condition; determining the DC equivalent resistance based on the effective value of the fundamental current and the load loss set; and determining the capacity expansion factor based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance.
[0044] In one embodiment of the present invention, determining the capacity expansion factor based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance includes: determining the fundamental load loss of the reference transformer under the fundamental wave operating condition based on the load loss set; determining the harmonic load loss of the reference transformer under the harmonic operating condition based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance; and determining the capacity expansion factor based on the fundamental load loss and the harmonic load loss.
[0045] In one embodiment of the present invention, determining the fundamental load loss of the reference transformer under fundamental operating conditions based on the load loss set includes: determining the fundamental load loss based on DC loss, eddy current loss, and stray loss, the expression of which is as follows:
[0046] in, For fundamental frequency load loss, The DC resistance of the winding. The DC resistance of the connecting wire. DC loss, For eddy current losses, For stray loss, This refers to the eddy current loss in the connecting wire. For stray losses of structural components, The reference transformer is defined as the effective value of the fundamental current at its rated current, specifically the root mean square value of the fundamental current at its rated current.
[0047] In one embodiment of the present invention, the harmonic load loss of the reference transformer under harmonic operating conditions is determined based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance, and its expression is as follows:
[0048] in, For harmonic load losses, For the effective value coefficient of non-sinusoidal line current, The DC resistance of the winding. The DC resistance of the connecting wire. To reference the DC loss of the transformer under harmonic conditions, The harmonic coefficient represents the eddy current loss. To reference the eddy current loss of the transformer under fundamental operating conditions, To reference the eddy current loss of a transformer under harmonic conditions, This is an additional coefficient for eddy current loss in the connecting line. To reference the eddy current loss of the connecting wires of the transformer under fundamental frequency conditions, To reference the eddy current loss of the connecting wires of a transformer under harmonic conditions, An additional coefficient is added for stray losses of structural components. To reference the stray losses of structural components in a transformer under fundamental frequency conditions, To reference the stray losses of structural components in a transformer under harmonic conditions, This is for reference transformer stray losses under harmonic conditions.
[0049] In practical applications, the increased losses under harmonic conditions are considered as equivalent heating current. With increased current and constant voltage, this can be equivalent to an increase in transformer capacity. The equivalent heating current under harmonic conditions is described in standard GB / T 18494.1-2014, Chinese standard title: Converter Transformers Part 1: Industrial Converter Transformers, and its expression is as follows:
[0050] in, This is the equivalent heating current under harmonic conditions. For harmonic load losses, For the effective value coefficient of non-sinusoidal line current, The DC resistance of the winding. The DC resistance of the connecting wire. To reference the DC loss of the transformer under harmonic conditions, The harmonic coefficient represents the eddy current loss. To reference the eddy current loss of the transformer under fundamental operating conditions, To reference the eddy current loss of a transformer under harmonic conditions, This is an additional coefficient for eddy current loss in the connecting line. To reference the eddy current loss of the connecting wires of the transformer under fundamental frequency conditions, To reference the eddy current loss of the connecting wires of a transformer under harmonic conditions, An additional coefficient is added for stray losses of structural components. To reference the stray losses of structural components in a transformer under fundamental frequency conditions, To reference the stray losses of structural components in a transformer under harmonic conditions, For reference transformer stray losses under harmonic conditions; For fundamental frequency load loss, The DC resistance of the winding. The DC resistance of the connecting wire. DC loss, For eddy current losses, For stray loss, This refers to the eddy current loss in the connecting wire. For stray losses of structural components, The reference transformer is defined as the effective value of the fundamental current at its rated current, specifically the root mean square value of the fundamental current at its rated current.
[0051] The standard number GB / T 18494.1-2014, Chinese standard name: Converter Transformers Part 1: Industrial Converter Transformers, also contains the formula for calculating the rated capacity, as follows:
[0052] in, For rated capacity, Rated voltage, The rated current is used in practical applications. Since the transformer input voltage and turns ratio remain constant, the only factor affecting transformer capacity expansion under different operating conditions is the current. Therefore, the rated current in the above formula for calculating rated capacity is replaced with the effective value of the fundamental current. The rated capacity under fundamental frequency conditions is obtained. Replace the rated current in the above formula for calculating rated capacity with the equivalent heating current under harmonic conditions. The rated capacity under harmonic operating conditions is obtained. .
[0053] In one embodiment of the present invention, the capacity enhancement factor is determined based on the fundamental load loss and harmonic load loss, and its expression is as follows:
[0054] in, This is the capacity expansion factor. For fundamental frequency load loss, This refers to harmonic load loss.
[0055] S4: Determine the capacity of the transformer to be designed based on the capacity expansion factor, including: obtaining the valve-side rated DC voltage and valve-side rated DC current of the transformer to be designed; and determining the capacity of the transformer to be designed based on the capacity expansion factor, the valve-side rated DC voltage, and the valve-side rated DC current.
[0056] In one embodiment of the present invention, the capacity of the transformer to be designed includes the valve-side capacity and the grid-side capacity. The valve-side capacity is the capacity of the transformer winding connected to the converter, and the grid-side capacity is the capacity of the transformer winding connected to the AC power grid, expressed as follows:
[0057]
[0058] in, For network-side capacity, Valve-side capacity, This is the capacity expansion factor. The rated DC voltage on the valve side. This refers to the rated DC current on the valve side. Traditional capacity determination methods do not consider the impact of harmonic conditions on transformer capacity. The traditional capacity expression is described in the document "Special Transformer Theory and Design," as follows:
[0059]
[0060] in, The network-side capacity is obtained using traditional methods. The valve-side capacity is obtained using traditional methods. The rated DC voltage on the valve side. The rated DC current on the valve side means that this invention modifies the traditional capacity calculation formula by using a capacity expansion factor M, converting the additional losses under harmonic conditions into an equivalent capacity margin. This ensures that the final transformer capacity can cover the additional heat demand caused by harmonic currents in actual operation. Compared with traditional methods, this avoids overload operation of the transformer under actual conditions due to ignoring the influence of harmonics, and ensures that the temperature rise of the transformer under actual operating conditions containing harmonics does not exceed the rated limit, effectively extending the service life of the transformer and reducing the risk of burnout.
[0061] Next, using a reference transformer with product model ZSCB-3300 / 6.6 / 2X0.434, we will explain how the capacity of the transformer to be designed, which has the same structure as the reference transformer, is determined using the capacity determination scheme of this invention: Load loss tests were conducted on the reference transformer under rated load at three frequencies: 50Hz (first frequency), 55Hz (second frequency), and 60Hz (third frequency). The load loss data are shown in Table 1 below. Table 1 Load Loss Data Table
[0062] Based on the data in Table 1, we substitute 20427W as the first load loss into the expression for the first load loss, 20780W as the second load loss into the expression for the second load loss, 21154W as the third load loss into the expression for the third load loss, 50Hz as the first frequency into the expressions for the second and third load losses, 55Hz as the second frequency into the expression for the second load loss, and 66Hz as the third frequency into the expression for the third load loss. This yields the following load loss set: DC loss is 17721W, eddy current loss is 1050W, and stray loss is 1656W.
[0063] Based on the harmonic content of a 6-pulse waveform, a set of harmonic coefficients for a reference transformer under odd-order harmonic conditions is obtained. Specifically, this set includes the effective value coefficients of the non-sinusoidal line current. It is 1.044 Eddy current loss harmonic coefficient The additional coefficient for eddy current loss in the connecting line is 16.83. and additional coefficient for stray losses of structural components All are used as stray loss harmonic coefficients, with a value of 1.5523.
[0064] Based on the above set of load losses and the set of harmonic coefficients under odd-harmonic conditions, the harmonic load loss of the reference transformer under odd-harmonic conditions is 1.044. 2 ×17721+16.83×1050+1.5523×1656=39557W, fundamental load loss is 20427W, calculate the capacity expansion factor. = That is, after considering odd harmonics, the capacity needs to be increased by about 39% in order to ensure that the temperature rise of the transformer under design does not exceed the rated limit.
[0065] By adding even-order harmonic content to the above-mentioned odd-order harmonic operating conditions, a set of harmonic coefficients for the reference transformer under both odd-order and even-order harmonic operating conditions is obtained. Specifically, this set includes the effective value coefficient of the non-sinusoidal line current. 1.204 Eddy current loss harmonic coefficient The additional coefficient for eddy current loss in the connecting line is 33.88. and additional coefficient for stray losses of structural components All are used as stray loss harmonic coefficients, with a value of 2.5752.
[0066] Based on the aforementioned load loss set and the harmonic coefficient set under odd and even harmonic conditions, the harmonic load loss of the reference transformer under odd harmonic conditions is 1.204. 2 ×17721+33.88×1050+2.5752×1656=65527W, fundamental load loss is 20427W, calculate the capacity expansion factor. = That is, after considering odd and even harmonics, the capacity needs to be increased by about 79% in order to ensure that the temperature rise of the transformer under design does not exceed the rated limit.
[0067] This invention employs a reference transformer with the same structure as the transformer under design. Under actual operating conditions, it measures load losses at different frequency points, accurately separating DC losses, eddy current losses, and stray losses. Combined with actual harmonics on-site, it determines the effective value coefficient of non-sinusoidal line current, the harmonic coefficient of eddy current loss, and the harmonic coefficient of stray loss. This allows for precise calculation of the equivalent load loss and capacity expansion coefficient under harmonic conditions. The capacity expansion coefficient is then incorporated into the traditional capacity calculation formula, achieving accurate correction of the transformer capacity. Compared to traditional capacity determination methods, this invention can accurately quantify the impact of harmonic current on transformer capacity based on the harmonic content under actual operating conditions. This ensures that the determined transformer capacity can cover the additional losses and temperature rise requirements caused by harmonics during actual operation, avoiding excessive temperature rise, shortened lifespan, or even burnout after transformer commissioning due to neglecting actual harmonic factors. This improves the operational reliability and service life of the transformer under actual harmonic conditions.
[0068] The present invention provides a capacity determination system for a double-reverse star transformer, applied to the aforementioned capacity determination method for a double-reverse star transformer, comprising: The data acquisition module is used to acquire the load loss set of the reference transformer under the fundamental operating condition of the transformer under design, and the effective value of each harmonic current of the reference transformer under the harmonic operating condition of the transformer under design. The data processing module is used for: Based on the effective values of each harmonic current and the set of load losses, determine the set of harmonic coefficients of the reference transformer under the harmonic operating conditions of the transformer to be designed. Based on the load loss set and the harmonic coefficient set, determine the capacity expansion factor used to quantify the impact of harmonic operating conditions on the reference transformer capacity; The capacity determination module is used to determine the capacity of the transformer to be designed based on the capacity expansion factor.
[0069] This invention discloses a computer device readable storage medium, which is a computer device readable storage medium storing a computer program thereon. When the computer program is executed, it implements the above-mentioned method for determining the capacity of a double anti-star transformer.
[0070] Optionally, the readable storage medium of the computer device may include: read-only memory (ROM), random access memory (RAM), solid-state drive (SSD), or optical disk, etc. The random access memory may include resistive random access memory (ReRAM) and dynamic random access memory (DRAM).
[0071] The computer device of the present invention includes a processor and a memory. The memory stores at least one instruction, at least one program, code set or instruction set. The processor loads and executes the at least one instruction, at least one program, code set or instruction set to implement the above-described method for determining the capacity of a double anti-star transformer.
[0072] The processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
[0073] Memory can be used to store computer programs or modules. The processor, by running or executing the computer programs or modules stored in the memory and calling data stored in the memory, implements various functions of the capacity determination method for the double-anti-star transformer. Memory can mainly include a program storage area and a data storage area. The program storage area can store the operating system, at least one application program required for a function, etc.; the data storage area can store data created based on terminal usage, etc. Furthermore, memory can include high-speed random access memory, and can also include non-volatile memory, such as hard disks, RAM, plug-in hard disks, SmartMediaCard (SMC), Secure Digital (SD) cards, FlashCards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.
[0074] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for determining the capacity of a double-reverse star-type transformer, characterized in that, include: Obtain the load loss set of the reference transformer under the fundamental operating condition of the transformer to be designed, and the effective value of each harmonic current of the reference transformer under the harmonic operating condition of the transformer to be designed. Based on the effective values of each harmonic current and the set of load losses, determine the set of harmonic coefficients of the reference transformer under the harmonic operating conditions of the transformer to be designed. Based on the load loss set and the harmonic coefficient set, a capacity expansion factor is determined to quantify the impact of the harmonic operating condition on the capacity of the reference transformer. The capacity of the transformer to be designed is determined based on the capacity expansion factor.
2. The method for determining the capacity of a double-reverse star transformer according to claim 1, characterized in that, The load loss set includes DC loss, eddy current loss, and stray loss; Obtain the set of load losses of the reference transformer under the fundamental operating conditions of the transformer to be designed, including: A load loss test was performed on the reference transformer under rated load and a first frequency to obtain the first load loss; A load loss test was performed on the reference transformer at rated load and a second frequency to obtain the second load loss. A load loss test was performed on the reference transformer at rated load and third frequency to obtain the third load loss. The DC loss, the eddy current loss, and the stray loss are obtained based on the first load loss, the second load loss, and the third load loss.
3. The method for determining the capacity of a double-reverse star transformer according to claim 1, characterized in that, The load loss set includes the eddy current loss of the reference transformer under the fundamental operating condition; Based on the effective values of each harmonic current and the set of load losses, the set of harmonic coefficients of the reference transformer under the harmonic operating conditions of the transformer to be designed is determined, including: The effective value of the fundamental current of the reference transformer under the fundamental operating condition, the harmonic order under the harmonic operating condition, and the winding eddy current loss of the reference transformer under the fundamental operating condition and when the leakage magnetic field shape meets the preset requirements are obtained. The set of harmonic coefficients is determined based on the effective values of each harmonic current, the eddy current loss of the reference transformer under the fundamental operating condition, the effective value of the fundamental current, the harmonic order, and the winding eddy current loss.
4. The method for determining the capacity of a double-reverse star transformer according to claim 3, characterized in that, The set of harmonic coefficients includes the effective value coefficient of non-sinusoidal line current, the harmonic coefficient of eddy current loss, and the harmonic coefficient of stray loss. Based on the effective values of each harmonic current, the eddy current loss of the reference transformer under the fundamental operating condition, the effective value of the fundamental current, the harmonic order, and the winding eddy current loss, the set of harmonic coefficients is determined, including: The effective value coefficient of the non-sinusoidal line current is determined based on the effective values of each harmonic current. The eddy current loss harmonic coefficient is determined based on the effective values of each harmonic current, the effective value of the fundamental current, the eddy current loss of the reference transformer under the fundamental operating condition, the harmonic order, and the winding eddy current loss. The stray loss harmonic coefficient is determined based on the effective values of each harmonic current, the effective value of the fundamental current, the eddy current loss of the reference transformer under the fundamental operating condition, and the harmonic order.
5. The method for determining the capacity of a double-reverse star transformer according to claim 1, characterized in that, Based on the load loss set and the harmonic coefficient set, a capacity expansion factor is determined to quantify the impact of the harmonic operating condition on the reference transformer capacity, including: Obtain the effective value of the fundamental current of the reference transformer under fundamental operating conditions; The DC equivalent resistance is determined based on the effective value of the fundamental current and the set of load losses. The capacitance factor is determined based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance.
6. The method for determining the capacity of a double-reverse star transformer according to claim 5, characterized in that, The capacitance factor is determined based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance, including: Based on the load loss set, determine the fundamental load loss of the reference transformer under the fundamental operating condition; Based on the load loss set, the harmonic coefficient set, and the DC equivalent resistance, the harmonic load loss of the reference transformer under the harmonic operating condition is determined. The capacity expansion factor is determined based on the fundamental load loss and the harmonic load loss.
7. The method for determining the capacity of a double-reverse star transformer according to claim 1, characterized in that, The capacity of the transformer to be designed is determined based on the capacity expansion factor, including: Obtain the valve-side rated DC voltage and valve-side rated DC current of the transformer to be designed; The capacity of the transformer to be designed is determined based on the capacity expansion factor, the rated DC voltage on the valve side, and the rated DC current on the valve side.
8. A capacity determination system for a double-reverse star transformer, applied to the capacity determination method for a double-reverse star transformer as described in any one of claims 1-7, characterized in that, include: The data acquisition module is used to acquire the load loss set of the reference transformer under the fundamental operating condition of the transformer under design, and the effective value of each harmonic current of the reference transformer under the harmonic operating condition of the transformer under design. The data processing module is used for: Based on the effective values of each harmonic current and the set of load losses, determine the set of harmonic coefficients of the reference transformer under the harmonic operating conditions of the transformer to be designed. Based on the load loss set and the harmonic coefficient set, a capacity expansion factor is determined to quantify the impact of the harmonic operating condition on the capacity of the reference transformer. The capacity determination module is used to determine the capacity of the transformer to be designed based on the capacity expansion factor.
9. A computer-readable storage medium, characterized in that, It is a computer-readable storage medium on which a computer program is stored, which, when executed, implements a method for determining the capacity of a double-reverse star transformer as described in any one of claims 1-7.
10. A computer device, characterized in that, The computer device includes a processor and a memory, the memory storing at least one instruction, at least one program, code set, or instruction set, the at least one instruction, at least one program, code set, or instruction set being loaded and executed by the processor to implement the capacity determination method for a double anti-star transformer as described in any one of claims 1 to 7.