Non-tapping voltage-adjustable method and transformer

Abstract

The invention relates to the technical field of non-tapping of transformers, in particular to a non-tapping voltage-adjustable method and a transformer, and the method comprises the step of determining the cross-sectional area of a non-tapping voltage-adjustable iron core and / or the number of turns of a winding according to an initial rated gear voltage value and a flux density and / or temperature rise design value. The transformer has the beneficial effects that by adopting the design method of low flux density and low temperature rise, the transformer successfully realizes the function of no-tapping voltage regulation, meanwhile, the material cost and the maintenance requirement are reduced, and the stability and the safety of a system are improved. The transformer is suitable for industrial and electric power systems needing high reliability and long service life, can adapt to power grid voltage fluctuation, and can maintain stable output voltage without manual intervention.

Description

Technical Field

[0001] The invention relates to the technical field of tapless transformer, in particular to a tapless voltage-adjustable method and a transformer. Background Art

[0002] Isolation transformers are commonly known as safety transformers. They are generally used to isolate impurities from the city grid and to maintain equipment. For isolation transformers of less than 1kV, if you want to achieve adjustable voltage, you need to set taps on the primary side, and usually the taps need to be led out with copper bars to achieve fine-tuning of the secondary voltage; and after the transformer is powered off, tools are used to change the taps to achieve voltage changes. This not only increases the workload of transformer production and manufacturing, but also increases the cost and volume of the transformer accordingly, and the voltage regulation range is relatively limited (usually linear voltage regulation, such as +5%, 0, -5%, etc.). Therefore, a low-voltage isolation transformer with no taps and adjustable voltage is considered. Summary of the invention

[0003] Some simplifications or omissions may be made in this section and the abstract and title of the present application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0004] In view of the above-mentioned prior art problems, the present invention is proposed.

[0005] The present invention aims to provide a tapless voltage-adjustable method, which aims to solve the problem of turns adjustment.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: a tapless adjustable voltage method, which comprises determining the cross-sectional area of ​​the tapless adjustable voltage core and / or the number of winding turns according to the initial rated voltage value, and the magnetic density and / or temperature rise design value.

[0007] As a preferred solution of the non-tap adjustable voltage method of the present invention, the initial rated voltage is 0.55 / 0.4 kV, and the magnetic density is 1.58 T; when the initial rated voltage is increased by 5%, the magnetic density is less than 1.7 T.

[0008] As a preferred solution of the non-tap adjustable voltage method of the present invention, the required core cross-sectional area is designed under the conditions that the initial rated voltage value is 0.55 / 0.4kV, the maximum floating is 5%, and the magnetic density is not greater than 1.7T. The formula is as follows:

[0009]

[0010] Among them, A represents the cross-sectional area of ​​the core; 450 is a constant; U represents the voltage of the transformer; B represents the magnetic flux density; and W represents the number of turns of the winding.

[0011] As a preferred solution of the non-tap adjustable voltage method of the present invention, the required number of winding turns is designed under the conditions that the initial rated voltage is 0.55 / 0.4 kV, the maximum floating is 5%, and the magnetic density is not greater than 1.7 T. The formula is as follows:

[0012]

[0013] Among them, W represents the number of turns of the winding; 450 is a constant; U represents the voltage of the transformer; B represents the magnetic flux density; and A represents the cross-sectional area of ​​the core.

[0014] As a preferred solution of the non-tap adjustable voltage method of the present invention, the required cross-sectional area of ​​the core and the number of turns of the winding are designed under the conditions that the initial rated voltage is 0.55 / 0.4 kV, the maximum floating is 5%, and the magnetic density is not greater than 1.7 T. The formula is as follows:

[0015]

[0016] Among them, e represents the induced electromotive force; 450 is a constant; B represents the magnetic flux density; A represents the cross-sectional area of ​​the iron core; U represents the voltage of the transformer; and W represents the number of turns of the winding.

[0017] As a preferred solution of the non-tap adjustable voltage method of the present invention, when the initial rated voltage is 0.55 / 0.4 kV and the minimum floating is 5%, it is ensured that the temperature rise becomes greater than 97K and less than 100K.

[0018] As a preferred solution of the non-tapped adjustable voltage method of the present invention, wherein: the value of the coil temperature rise is determined according to the load loss, the coil loss temperature rise and the floating value, ensuring that the value of the temperature rise plus the rated temperature does not reach 100K

[0019] As a preferred solution of the tapless voltage-adjustable method of the present invention, the load loss is expressed as follows:

[0020] P=P1+P2=3I 2 R+3I 2 RK%

[0021] Among them, P1 represents the power loss; P2 is the wire loss; K% is the percentage of eddy current loss in the wire to the resistance loss; I represents the current passing through the transformer winding; R represents the resistance of the transformer winding; the coefficient of 3 is because in a three-phase system, the loss of each phase needs to be multiplied by 3 to get the total copper loss.

[0022] As a preferred solution of the non-tapped adjustable voltage method of the present invention, the coil loss temperature rise is calculated as follows:

[0023]

[0024] Calibration temperature rise

[0025]

[0026] Where τ represents temperature rise in Kelvin; P represents active power; Q represents reactive power in VAR; ∑ 1-j Q represents the sum of reactive powers of all phases; 0.75 is an empirical coefficient used to convert power ratio into the magnitude of temperature rise; 80 is a constant used to convert the calculated result into the actual temperature rise value; Δτ represents the calibrated temperature rise; P represents the power loss under load, in watts (W); S represents the apparent power, in volt-amperes (VA); δ represents efficiency or other related coefficients; 0.005 is a coefficient used to convert power loss into temperature rise.

[0027] As a preferred solution of the non-tapped adjustable voltage method of the present invention, the temperature rise of the coil is as follows:

[0028]

[0029] Among them, G j Comprehensive weight; G 铜 is the copper wire weight; j is the time.

[0030] The beneficial effects of the tapless voltage-adjustable method of the present invention are as follows: by adopting a design method of low magnetic density and low temperature rise, the transformer successfully realizes the tapless voltage-adjustable function, while reducing material costs and maintenance requirements, and improving the stability and safety of the system. The transformer is suitable for industrial and power systems that require high reliability and long life, can adapt to grid voltage fluctuations, and can maintain a stable output voltage without manual intervention.

[0031] Another object of the present invention is to provide a transformer, which aims to solve the problem of adjusting the number of turns.

[0032] In order to solve the above technical problems, the present invention also provides the following technical solutions: comprising an iron core, an isolation transformer coil sleeved outside the iron core, wherein the isolation transformer coil comprises a primary side isolation transformer coil and a secondary side isolation transformer coil; an input end provided at one end of the primary side isolation transformer coil and an output end provided at one end of the secondary side isolation transformer coil;

[0033] A support frame is arranged below the iron core.

[0034] As a preferred solution of the transformer of the present invention, wherein: three isolation transformer coils are provided, and the iron cores are connected to each other;

[0035] Each of the isolation transformer coils is provided with an input end and an output end at both ends, and the input ends are connected to each other by a connecting plate, and the output ends are connected to each other by a connecting plate;

[0036] The input end comprises an external input copper busbar and an external input connection copper busbar, and the input copper busbar is provided with an external input hole and an internal connection hole;

[0037] The output end includes an external output copper busbar and an external output connecting copper busbar.

[0038] As a preferred solution of the transformer of the present invention, wherein: mounting plates are respectively provided at both ends of the iron core, and a fixing block and a buffer are provided between the mounting plate and the isolation transformer coil.

[0039] The transformer of the present invention has the beneficial effect of solving the problem of manually using tools to replace copper bars and change the number of tap turns to adjust the gear to meet voltage changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0041] Figure 1 It is a side view of the transformer structure in the present invention.

[0042] Figure 2 It is a front view of the transformer structure in the present invention.

[0043] Figure 3 It is the rear view of the transformer structure in the present invention.

[0044] Figure 4 This is an axial view of the transformer structure in the present invention.

[0045] Figure 5 It is a schematic diagram of the isolation transformer coil and its matching structure in the present invention.

[0046] Figure 6 It is a top view of the isolation transformer coil and matching structure in the present invention.

[0047] Figure 7 It is a front view of the isolation transformer coil and matching structure in the present invention. DETAILED DESCRIPTION

[0048] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0049] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0050] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

[0051] Example 1

[0052] This is the first embodiment of the present invention, which provides a tapless adjustable voltage method, including determining the cross-sectional area of ​​the core and / or the number of winding turns of the tapless adjustable voltage according to the initial rated voltage value, and the magnetic density and / or temperature rise design value. The initial rated voltage is 0.55 / 0.4kV, and the magnetic density is 1.58T; when the initial rated voltage is increased by 5%, the magnetic density is less than 1.7T. The initial rated voltage is 0.55 / 0.4kV, and the temperature rise design value is 89K; when the voltage is decreased by 5%, the temperature rise becomes greater than 97K and less than 100K.

[0053] Among them, the transformer has core components such as iron core and winding, and the winding is divided into two variable coils. According to the number of turns of different variable coils, the input voltage is adjusted to the voltage required by the load; then according to the magnetic density requirement of 1.58T, the required iron core cross-sectional area is calculated, and the appropriate cold-rolled silicon steel sheet thickness and number of stacking sheets are selected to ensure that the iron core will not be saturated and meet the magnetic density requirements.

[0054] Winding design: The two transformer coils in the winding are divided into primary side isolation transformer coil and secondary side isolation transformer coil; calculate the required number of winding turns to meet the voltage ratio of 0.55 / 0.4kV, while considering the cross-sectional area of ​​the wire to ensure that the temperature rise does not exceed 89K under maximum load.

[0055] By adopting the design method of low magnetic density and low temperature rise, the transformer successfully realizes the function of tapless voltage regulation, while reducing material costs and maintenance requirements, and improving the stability and safety of the system. The transformer is suitable for industrial and power systems that require high reliability and long life. It can adapt to grid voltage fluctuations and maintain a stable output voltage without manual intervention.

[0056] Example 2

[0057] For the second embodiment of the present invention, when selecting the magnetic flux density of the transformer, engineers usually consider the magnetic flux density of the transformer under the most unfavorable working conditions to ensure the long-term reliability and efficiency of the transformer. In this example, we selected a lower magnetic flux density value of 1.58T as the design basis. The purpose of this is to ensure that even when the voltage floats to the highest working point, the magnetic flux density will not exceed the safe value, thereby avoiding magnetic saturation, reducing iron loss, reducing noise, and extending the service life of the transformer.

[0058] To determine the number of turns in a winding, we can use the following formula:

[0059]

[0060] During the design process, determine the voltage ratio between the primary and secondary sides: According to the design requirements of the transformer, determine the voltage ratio between the primary and secondary sides, that is, u1 / u2; the magnetic flux density B we hope to achieve (1.58T in this case). Then, we can calculate the number of turns required for the primary and secondary sides (w1 and w2), and then determine the cross-sectional area A of the core.

[0061] To determine the cross-sectional area A of the core, we can use the following formula:

[0062]

[0063] Based on the voltage ratio and the voltage on each side, we can calculate the number of turns required for the primary and secondary sides. The number of turns is proportional to the voltage and inversely proportional to the flux density and the cross-sectional area of ​​the core. Design core cross-sectional area: Using the above formula, we can calculate the cross-sectional area A required to adjust the core in order to achieve the required number of turns at a given flux density value.

[0064] Design the coil: Design the primary and secondary isolation transformer coils based on the calculated number of turns and core cross-sectional area. Ensure that the coil size matches the core and that the coil winding method can meet the requirements of tapless voltage regulation. Ensure that the number of turns does not change when the voltage fluctuates: By selecting the appropriate wire cross-sectional area and winding technology, ensure that the number of turns of the coil does not need to change when the voltage fluctuates, thereby achieving tapless voltage regulation.

[0065] In the field of transformers, voltage changes can affect the magnetic flux density and current of the transformer, which in turn affect losses and temperature rise. We can calculate the parameters of the primary side without tap-changing regulating leads and the secondary side without tap-changing regulating leads when the voltage drops by 5% and the temperature rise changes from 89K to greater than 97K but less than 100K through the following steps. First, we consider the case of a 5% voltage drop: Since the number of turns of the transformer remains unchanged and voltage is proportional to current, the current will also increase by 5%. The increase in current will lead to an increase in copper loss, and the copper loss is proportional to the square of the current. Determine the terminal voltage; consider the load loss, coil loss temperature rise, and floating value to determine the value of the coil temperature rise. Assume the copper loss under the original conditions is P1. Since the voltage increases by 5%, the new copper loss is P2. Then, use the calibrated temperature rise formula to calculate the copper temperature rise and use the coil temperature rise formula to calculate the comprehensive coil temperature rise. If the new temperature rise plus the rated temperature does not reach 100K, the design is reasonable, thus achieving a design with a low temperature rise, improving the stability of the overall equipment under load conditions, and realizing a transformer without taps.

[0066] That is, the steps are as follows: (Here, for a 50Hz transformer, the load loss at 75°C)

[0067] Determine the design parameters, initial rated voltage: 0.55 / 0.4kV; initial temperature rise design value: 89K; voltage drop ratio: 5%; new voltage on the primary side: 0.55kV × 0.95; new voltage on the secondary side: 0.4kV × 0.95.

[0068] Current change: Since the voltage decreases, the current will increase. Use the voltage and current relationship of the transformer to estimate the new current value.

[0069] First, calculate the load consumption, P = P1 + P2 = 3I 2 R + 3I 2 RK%

[0070] Among them,

[0071] f is the frequency; H k --Average reactance height; a---Thickness of a single wire (bare wire); s---Cross-sectional area of a single wire (mm); p---Rockwell coefficient; m---Total number of wires perpendicular to the direction of the leakage magnetic field; For continuous winding: m = 卬 * m = number of turns per section * number of parallel strands; For spiral winding: m = number of parallel strands per turn of wire; n---Total number of wires parallel to the direction of the leakage magnetic field; For continuous winding: n = total number of coil sections; For spiral winding: n = number of turns * number of spirals; Then calculate the power generated under load conditions.

[0072] Calculate the new coil temperature rise: Use the following formula:

[0073]

[0074] Calibration temperature rise

[0075]

[0076] Comprehensive formula for coil temperature rise,

[0077]

[0078] By calculating the comprehensive temperature rise, if the comprehensive temperature rise can reach less than 100K under load, the number of coil turns is designed reasonably; by adjusting the parameters in the above formula, the temperature rise can be controlled within the tolerance range of the equipment under load. The size, material and cooling system of the coil can be designed according to the new current and copper loss. Consider using a more conductive material or increasing the cross-sectional area of ​​the coil to reduce resistance and copper loss, etc., to adjust the comprehensive temperature rise and achieve a low temperature rise.

[0079] By using a lower magnetic flux density, when the transformer is at the highest voltage (5% higher than the rated voltage), it avoids the problems of core overheating, insulation damage, transformer damage, etc. caused by long-term operation when the gear is not adjusted. It also avoids the problem that the output voltage cannot reach the rated value due to the magnetic flux saturation of the conventional isolation transformer, thereby ensuring that the output voltage meets the requirements of the secondary side load.

[0080] When the transformer is at the lowest voltage, conventional transformers will increase the transformer temperature by more than 10% of 100K, destroying insulation and reducing service life. This isolation transformer selects the appropriate wire cross-sectional area to ensure that the temperature rise is still less than 100K (F-level temperature rise requirement) at the lowest voltage.

[0081] When the voltage on the grid input side is 0.55*(-5%~+5%), conventional isolation transformers usually change the voltage by tapping the primary side, and a power outage is required to change the tap position. This patent does not require gear adjustment, and can meet the voltage change requirements without power outage and gear switching.

[0082] Example 3

[0083] Reference Figures 1 to 7 , which is the third embodiment of the present invention, and this embodiment further provides a transformer. It includes an iron core 101, an isolation transformer coil 102 sleeved outside the iron core 101, wherein the isolation transformer coil 102 includes a primary side isolation transformer coil 102a and a secondary side isolation transformer coil 102b; an input terminal 103 provided at one end of the primary side isolation transformer coil 102a and an output terminal 104 provided at one end of the secondary side isolation transformer coil 102b;

[0084] A support frame 200 is disposed below the iron core 101 .

[0085] Among them, the iron core 101, the primary side isolation transformer coil 101a and the secondary side isolation transformer coil 101b are designed using a tapless adjustable voltage method. The corresponding size parameters of the iron core 101, the primary side isolation transformer coil 101a and the secondary side isolation transformer coil 101b are designed according to the tapless adjustable voltage method to ensure that the equipment can operate stably under load conditions.

[0086] The isolation transformer coils 102 are provided with three, and the iron cores 102 are connected to each other;

[0087] Each of the isolation transformer coils 102 is provided with an input end 103 and an output end 104 at both ends, and the input ends 1030 are connected to each other by a connecting plate M, and the output ends 104 are connected to each other by a connecting plate M;

[0088] The input end 103 comprises an external input copper busbar 103a and an external input connection copper busbar 103b, wherein the input copper busbar 103a is provided with an external input hole 103a-1 and an internal connection hole 103a-2;

[0089] The output end 104 includes an external output copper bus 104a and an external output connection copper bus 104b

[0090] The input terminal 103 is arranged on the upper surface of the primary side isolation transformer coil 101a, and the three input terminals 103 are connected by a connecting plate M. Figure 4As shown, the external input connection copper bar 103b of the first input end 103 on the left is connected to the internal input copper bar 103a of the middle input end 103 through the connection plate M, and the external input connection copper bar 103b of the middle input end 103 is connected to the internal input copper bar 103a of the right input end 103 through the connection plate M; the external output connection copper bar 103a of the first input end 103 on the left is connected to the internal input copper bar 103b of the right input end 103 through the connection plate M; wherein the connection plate M can be adjusted to different shapes according to the space, so as to complete the connection and prevent mutual staggering; at the same time, the external input copper bar 103a is fixedly connected to the primary side isolation transformer coil 101a, and the external input copper bar 103a and the external input connection copper bar 103b are divided into three sections, wherein the first section 103a-1 of the external input copper bar is parallel to the first section 103b-1 of the external input connection copper bar. The external input copper bar is arranged in a row and vertically inserted into the primary side isolation transformer coil 101a. The second section 103a-2 of the external input copper bar and the second section 103b-2 of the external input connection copper bar are both folded outward and are not parallel. Then the third section 103a-3 of the external input copper bar and the third section 103b-3 of the external input connection copper bar are extended in the vertical direction. At the same time, the third section 103a-3 of the external input copper bar and the third section 103b-3 of the external input connection copper bar are parallel. Since the second section 103a-2 of the external input copper bar and the second section 103b-2 of the external input connection copper bar are not arranged in parallel, the distance between the third section 103a-3 of the external input copper bar and the third section 103b-3 of the external input connection copper bar becomes larger, thereby providing space for installing the insulator 103c. At the same time, the isolated space also prevents the external input voltage from directly contacting the internal coil, causing a short circuit or other situations. Similarly, if Figure 4As shown, three external output connection copper bars 104b are connected together through a connection plate M, wherein the external output copper bars 104a and the external output connection copper bars 104b are both divided into three sections, wherein the first section 104a-1 of the external output copper bar is parallel to the first section 104b-1 of the external output connection copper bar, and is vertically inserted into the lower surface of the secondary side isolation transformer coil 101b, the second section 104b-2 of the external output copper bar is folded outwards and is not parallel to the second section 104b-2 of the external output copper bar, and then the third section 104a-3 of the external output copper bar is vertically extended upwards with the third section 104b-3 of the external output copper bar, and at the same time, the third section 104a-3 of the external output copper bar is parallel to the external output connection copper bar. The third section 103b-3 of the external output copper bar is parallel to the third section 103b-3 of the external output copper bar; since the second section 104a-2 of the external output copper bar is not arranged in parallel with the second section 104b-2 of the external output connection copper bar, the distance between the third section 104a-3 of the external output copper bar and the third section 104b-3 of the external output connection copper bar becomes larger, thereby providing space for installing the insulator 103c. At the same time, the isolated space also prevents the external input voltage from directly contacting the internal coil, causing a short circuit or other situations; at the same time, the third section 104a-3 of the external input connection copper bar and the third section 104b-3 of the external output connection copper bar are both provided with a first screw hole 104a-4 for grid input and a second screw hole 104a-5 for screwing the connection plate M.

[0091] This plan needs to explain that if Figure 2 As shown, there is a height difference h between the mounting plate 105 and the input end 103, and the height difference h is greater than 0; the advantage of such a design is that the externally connected devices above can be more convenient for people to observe.

[0092] Mounting plates 105 are respectively provided at both ends of the iron core 101 , and a fixing block 106 and a buffer member 107 are provided between the mounting plate 105 and the isolation transformer coil 102 .

[0093] Among them, mounting plates 105 are fixedly arranged at the upper and lower ends of the iron core 101, the upper mounting plate 105 extends a straight plate 105a toward the input end 103, and the lower mounting plate 105 extends a straight plate 105a toward the output end 104. The main function of the straight plate 105a is to connect the fixing block 106 with the straight plate 105 through bolts, and a buffer 107 is placed between the fixing block 106 and the isolation transformer coil 102. The buffer 107 is made of deformable material, and its main function is to provide a buffer to prevent the isolation transformer coil 102 from shaking during transportation of the equipment, thereby increasing the service life of the equipment.

[0094] The mounting plate 105 below is screwed to the support frame 200 by bolts, wherein the support frame 200 includes two horizontal square tubes 201, and below the horizontal square tubes 201 there are two vertical square tubes 202 placed perpendicular to the horizontal square tubes 201, which support the above structure, lift it off the ground, and improve moisture resistance.

[0095] The iron core adopts a parametric design with low magnetic density to complete the production and assembly of the iron core. The isolation coil adopts a low electrical density design. After winding and pouring, it is mounted on the iron core. At the same time, the coil needs to be connected to the tap copper bar 101. The present invention adopts a single tap copper bar 101 to replace the original multiple tap copper bars. When in use, there is no need to switch the tap or adjust the gear position to meet the impact of voltage changes on the transformer. This solves the problem of manually using tools to change the copper bar to change the number of tap turns to adjust the gear to meet the voltage change.

[0096] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0097] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0098] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0099] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A tapless voltage-adjustable method, characterized in that: include, The cross-sectional area of ​​the core and / or the number of winding turns of the non-tapped adjustable voltage are determined according to the initial rated voltage value, and the magnetic density and / or temperature rise design value.

2. The tapless voltage-adjustable method according to claim 1, characterized in that: When the initial rated voltage value is 0.55 / 0.4 kV and the maximum increase is 5%, it is ensured that the magnetic flux density is not greater than 1.7 T.

3. The tapless voltage-adjustable method according to claim 2, characterized in that: Under the conditions that the initial rated voltage is 0.55 / 0.4kV, the maximum floating is 5%, and the magnetic density is not greater than 1.7T, the required core cross-sectional area is designed according to the following formula: Among them, A represents the cross-sectional area of ​​the core; 450 is a constant; U represents the voltage of the transformer; B represents the magnetic flux density; and W represents the number of turns of the winding.

4. The tapless voltage-adjustable method according to claim 2, characterized in that: Under the conditions that the initial rated voltage is 0.55 / 0.4kV, the maximum floating is 5%, and the magnetic density is not greater than 1.7T, the required number of winding turns is designed, and the formula is as follows: Among them, W represents the number of turns of the winding; 450 is a constant; U represents the voltage of the transformer; B represents the magnetic flux density; and A represents the cross-sectional area of ​​the core.

5. The tapless voltage-adjustable method according to claim 2, characterized in that: The required cross-sectional area of ​​the core and the number of turns of the winding are designed under the conditions that the initial rated voltage is 0.55 / 0.4kV, the maximum floating is 5%, and the magnetic density is not greater than 1.7T. The formula is as follows: Among them, e represents the induced electromotive force; 450 is a constant; B represents the magnetic flux density; A represents the cross-sectional area of ​​the iron core; U represents the voltage of the transformer; and W represents the number of turns of the winding.

6. The tapless voltage regulating method according to any one of claims 1 to 5, characterized in that: When the initial rated voltage is 0.55 / 0.4 kV and the minimum floating is 5%, it is ensured that the temperature rise becomes greater than 97K and less than 100K.

7. A method for evaluating a tapless adjustable voltage method, characterized in that: The value of the coil temperature rise is determined based on the load loss, coil loss temperature rise and floating value, ensuring that the value of the temperature rise plus the rated temperature does not reach 100K.

8. The evaluation method of the tapless adjustable voltage method according to claim 7, characterized in that: The load loss formula is as follows: <h2 style=";text-align:left;direction:ltr">P = P1 + P2 = 3I<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> R+3I<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> RK% Among them, P1 represents the power loss; P2 is the wire loss; K% is the percentage of eddy current loss in the wire to the resistance loss; I represents the current passing through the transformer winding; R represents the resistance of the transformer winding; the coefficient of 3 is because in a three-phase system, the loss of each phase needs to be multiplied by 3 to get the total copper loss.

9. The evaluation method for the tapless adjustable voltage method according to claim 7 or 8, characterized in that: The coil loss temperature rise is as follows: Calibration temperature rise Where τ represents temperature rise in Kelvin; P represents active power; Q represents reactive power in VAR; ∑ 1-j Q represents the sum of reactive powers of all phases; 0.75 is an empirical coefficient used to convert power ratio into the magnitude of temperature rise; 80 is a constant used to convert the calculated result into the actual temperature rise value; Δτ represents the calibrated temperature rise; P represents the power loss under load, in watts (W); S represents the apparent power, in volt-amperes (VA); δ represents efficiency or other related coefficients; 0.005 is a coefficient used to convert power loss into temperature rise.

10. The evaluation method for the tapless adjustable voltage method according to claim 7 or 8, characterized in that: The coil temperature rise is given by the following formula: Among them, G j Comprehensive weight; G 铜 is the copper wire weight; j is the time.

11. A transformer, characterized in that: The invention comprises an iron core (101), and an isolation transformer coil (102) sleeved outside the iron core (101), wherein the isolation transformer coil (102) comprises a primary side isolation transformer coil (102a) and a secondary side isolation transformer coil (102b); an input end (103) arranged at one end of the primary side isolation transformer coil (102a) and an output end (104) arranged at one end of the secondary side isolation transformer coil (102b); A support frame (200) is arranged below the iron core (101).

12. The transformer according to claim 11, characterized in that: The isolation transformer coils (102) are provided in three pieces, and the iron cores (102) are connected to each other; Each of the isolation transformer coils (102) is provided with an input end (103) and an output end (104) at both ends, and the input ends (1030) are connected to each other via a connection plate (M), and the output ends (104) are connected to each other via a connection plate (M); The input end (103) comprises an external input copper busbar (103a) and an external input connection copper busbar (103b); the input copper busbar (103a) is provided with an external input hole (103a-1) and an internal connection hole (103a-2); The output end (104) comprises an external output copper busbar (104a) and an external output connecting copper busbar (104b).

13. The transformer according to claim 12, characterized in that: Mounting plates (105) are respectively provided at both ends of the iron core (101), and a fixing block (106) and a buffer component (107) are provided between the mounting plate (105) and the isolation transformer coil (102).

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