Single-phase autotransformer with built-in impedance adjusting winding and adjusting method of single-phase autotransformer

Abstract

The invention discloses a single-phase autotransformer with a built-in impedance adjusting winding and an adjusting method of the single-phase autotransformer. The single-phase autotransformer comprises an iron core, a series winding, a common winding, a voltage regulating winding, a low-voltage winding and an impedance regulating winding, the low-voltage winding is arranged between the iron core and the impedance regulating winding, and the common winding is arranged between the impedance regulating winding and the series winding; the voltage regulating winding is arranged on the outermost side; the tail end of the series winding is connected with the head end of the common winding, the tail end of the common winding is connected to the head end of the impedance adjusting winding, and the tail end of the impedance adjusting winding is connected to the head end of the voltage adjusting winding; the impedance adjusting winding comprises two coils and is provided with a tap A, a tap B and a tap C. The short-circuit impedance of the transformer is adjusted by switching the connection positions of the tail end of the public winding and the different taps of the impedance adjusting winding, and the voltage transformation ratio of the transformer is not changed in the impedance adjusting process. Through an impedance adjusting function, the stability of the power grid and the load capacity of the main transformer are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of single-phase autotransformer technology, and in particular to a single-phase autotransformer with a built-in impedance regulating winding and its regulating method. Background Technology

[0002] 500kV transformers are key core equipment in hub substations. Most 500kV transformers are single-phase autotransformers. When a major defect or fault occurs that cannot be repaired on-site, the transformer needs to be returned to the factory for repair. An excessively long repair cycle will affect the safe operation of the power grid. Therefore, if one phase fails and needs to be taken out of service, replacing it with a spare phase can be considered to restore overall operation. Replacing the faulty phase with a spare transformer of the same model can shorten the main transformer outage time and alleviate the power supply pressure in the area. Configuring a sufficient number of spare transformers that meet operating conditions is an effective method to meet the requirements of emergency repair and rapid power supply restoration. However, due to the long production cycle of 500kV transformers, the timeliness of temporarily producing a spare after a fault is poor, and the power system faces the risk of prolonged outages. Furthermore, when connected to the grid, it is difficult to ensure that the impedance parameters of the spare phase and the original transformer are completely identical. Replacement may lead to asymmetry in the three-phase parameters of the main transformer, resulting in unbalanced electrical quantities during operation, affecting the operating characteristics and load capacity of the main transformer. In order to enable transformers to serve as backup phases for transformers with different voltages and impedances, it has become an urgent problem to develop a backup phase transformer that can simultaneously adjust voltage and impedance values ​​to adapt to multiple transformers.

[0003] The information disclosed in the background section is only intended to enhance the understanding of the background of the present invention, and therefore may contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] To address the shortcomings or defects of the existing technology, a single-phase autotransformer and method with a built-in impedance regulating winding are provided to solve the problem of low voltage and impedance compatibility of current 500kV transformers.

[0005] The objective of this invention is achieved through the following technical solutions.

[0006] In a first aspect, the present invention provides a single-phase autotransformer with a built-in impedance regulating winding, comprising a core, a series winding, a common winding, a voltage regulating winding, a low-voltage winding, and an impedance regulating winding, wherein... The low-voltage winding is positioned between the iron core and the impedance regulating winding; The common winding is positioned between the impedance adjustment winding and the series winding; The voltage regulating winding is located on the outermost side; The end of the series winding is connected to the beginning of the common winding, the end of the common winding is connected to the beginning of the impedance adjustment winding, and the end of the impedance adjustment winding is connected to the beginning of the voltage adjustment winding. The impedance regulating winding includes two coils and is equipped with taps A, B and C. By switching the connection positions of the end of the common winding with different taps of the impedance regulating winding, the short-circuit impedance of the transformer can be adjusted without changing the voltage ratio of the transformer during the impedance adjustment process.

[0007] Preferably, in the single-phase autotransformer with built-in impedance regulating winding, the voltage regulating winding is provided with multiple taps for independent adjustment of the medium-voltage side voltage.

[0008] Preferably, in the single-phase autotransformer with built-in impedance regulating winding, the series winding has a centrally input structure, including an upper series winding and a lower series winding arranged in parallel.

[0009] Preferably, in the single-phase autotransformer with built-in impedance regulating winding, the two coils in the impedance regulating winding are connected with opposite magnetic polarities under different tap states, so as to control the amount of magnetic energy absorbed during transformer operation and change the leakage flux distribution to achieve impedance regulation.

[0010] Preferably, in the single-phase autotransformer with built-in impedance regulating winding, the short-circuit impedance of the transformer is minimized when the end of the common winding is connected to tap B of the impedance regulating winding; the short-circuit impedance of the transformer is maximized when the end of the common winding is connected to tap A of the impedance regulating winding; and the short-circuit impedance of the transformer is both smaller than the maximum and larger than the minimum when the end of the common winding is connected to tap C of the impedance regulating winding.

[0011] Preferably, in the single-phase autotransformer with built-in impedance regulating winding, the transformer impedance parameters and medium-voltage output voltage are decoupled and controlled by adjusting the taps of the impedance regulating winding and the tap positions of the voltage regulating winding respectively.

[0012] Preferably, in the single-phase autotransformer with built-in impedance adjustment winding, the single-phase autotransformer is used as a spare phase in the phase autotransformer group, and its impedance value is adjusted to match the original impedance parameters of different operating phases.

[0013] Preferably, in the single-phase autotransformer with built-in impedance regulating winding, the transformer impedance is at least 21.61% and at most 41.66%.

[0014] Preferably, in the single-phase autotransformer with built-in impedance regulating winding, the single-phase autotransformer is a 500kV single-phase autotransformer.

[0015] Secondly, the present invention provides a method for adjusting the above-mentioned single-phase autotransformer with built-in impedance adjusting winding, comprising: Detect the original impedance parameters of the transformer in the faulty phase; Switch the end of the common winding of the standby phase transformer to the tap A, tap B or tap C corresponding to the impedance regulating winding so that its short-circuit impedance matches the fault. Adjust the tap position of the voltage regulating winding so that the output voltage on the medium voltage side meets the system operating requirements; The adjusted backup phase is put into operation to replace the faulty phase, thus achieving rapid power restoration.

[0016] Compared with existing technologies, the present invention has the following advantages: By incorporating taps A, B, and C of a built-in segmented impedance regulating winding and an independent voltage regulating winding, the transformer impedance value can be precisely adjusted (tap A has the highest impedance, tap B has the lowest impedance) without changing the voltage ratio, simply by switching the connection positions of the taps of the common winding and the impedance regulating winding (e.g., A / B / C). Simultaneously, independent voltage regulation on the medium-voltage side is achieved through the tap-connection of the voltage regulating winding. Traditionally, impedance differences in the standby phase lead to three-phase parameter imbalance, causing unbalanced operation of the power grid. The present invention, through its impedance regulation function, enables the same standby transformer to dynamically match the impedance parameters of multiple faulty transformers, eliminating the three-phase asymmetry problem after replacement and ensuring power grid stability and the main transformer's load capacity.

[0017] The description provided is merely an overview of the technical solution of this invention. In order to make the technical means of this invention clearer and more understandable, so that those skilled in the art can implement it according to the contents of the specification, and to make the described and other objects, features and advantages of this invention more obvious and understandable, specific embodiments of this invention are described below. Attached Figure Description

[0018] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0019] In the attached diagram: Figure 1 This is a winding arrangement diagram of a 500kV single-phase autotransformer with a built-in impedance adjustment winding proposed in this invention. Figure 2This is a winding connection diagram of a 500kV single-phase autotransformer with a built-in impedance adjustment winding proposed in this invention. Figure 3 This is a schematic diagram of the impedance adjustment of a 500kV single-phase autotransformer with a built-in impedance adjustment winding proposed in this invention.

[0020] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0021] Specific embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0022] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0023] To facilitate understanding of the embodiments of the present invention, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0024] To better understand, such as Figure 1-3 As shown, a single-phase autotransformer with a built-in impedance regulating winding includes an iron core, a series winding, a common winding, a voltage regulating winding, a low-voltage winding, and an impedance regulating winding, wherein... The low-voltage winding is positioned between the iron core and the impedance regulating winding; The common winding is positioned between the impedance adjustment winding and the series winding; The voltage regulating winding is located on the outermost side; The end of the series winding is connected to the beginning of the common winding, the end of the common winding is connected to the beginning of the impedance adjustment winding, and the end of the impedance adjustment winding is connected to the beginning of the voltage adjustment winding. The impedance regulating winding includes two coils and is equipped with taps A, B, and C. By switching the connection positions of the end of the common winding with different taps of the impedance regulating winding, the short-circuit impedance of the transformer can be adjusted without changing the voltage ratio of the transformer during the impedance adjustment process.

[0025] In a preferred embodiment of the single-phase autotransformer with built-in impedance regulating winding, the voltage regulating winding is provided with multiple taps for independent adjustment of the medium-voltage side voltage.

[0026] In a preferred embodiment of the single-phase autotransformer with built-in impedance regulating winding, the series winding has a centrally input structure, including an upper series winding and a lower series winding connected in parallel.

[0027] In a preferred embodiment of the single-phase autotransformer with built-in impedance regulating winding, the two coils in the impedance regulating winding are connected with opposite magnetic polarities under different tap states to control the amount of magnetic energy absorbed during transformer operation and change the leakage flux distribution to achieve impedance regulation.

[0028] In a preferred embodiment of the single-phase autotransformer with built-in impedance regulating winding, the short-circuit impedance of the transformer is minimum when the end of the common winding is connected to tap B of the impedance regulating winding; the short-circuit impedance of the transformer is maximum when the end of the common winding is connected to tap A of the impedance regulating winding; and the short-circuit impedance of the transformer is intermediate when the end of the common winding is connected to tap C of the impedance regulating winding.

[0029] In a preferred embodiment of the single-phase autotransformer with built-in impedance regulating winding, decoupling control of the transformer impedance parameters and medium-voltage output voltage is achieved by adjusting the taps of the impedance regulating winding and the tap positions of the voltage regulating winding respectively.

[0030] In a preferred embodiment of the single-phase autotransformer with built-in impedance adjustment winding, the single-phase autotransformer is used as a spare phase in the phase autotransformer group, and its impedance value is adjusted to match the original impedance parameters of different operating phases.

[0031] In a preferred embodiment of the single-phase autotransformer with built-in impedance regulating winding, the transformer impedance is at least 21.61% and at most 41.66%.

[0032] In a preferred embodiment of the single-phase autotransformer with built-in impedance regulating winding, the single-phase autotransformer is a 500kV single-phase autotransformer.

[0033] The adjustment methods for a single-phase autotransformer with a built-in impedance regulating winding include: Detect the original impedance parameters of the transformer in the faulty phase; Switch the end of the common winding of the standby phase transformer to the tap A, tap B or tap C corresponding to the impedance regulating winding so that its short-circuit impedance matches the fault. Adjust the tap position of the voltage regulating winding so that the output voltage on the medium voltage side meets the system operating requirements; The adjusted backup phase is put into operation to replace the faulty phase, thus achieving rapid power restoration.

[0034] In one embodiment, a 500kV single-phase autotransformer with a built-in impedance regulating winding includes a series winding, a common winding, an impedance regulating winding, a voltage regulating winding, a low-voltage winding, and a core. The low-voltage winding is located between the core and the impedance regulating coil, the common winding is located between the impedance regulating winding and the series winding, and the voltage regulating winding is located on the outermost side.

[0035] The end of the series winding is connected in series with the beginning of the common winding, the end of the common winding is connected in series with the beginning of the impedance adjustment winding, and the end of the impedance adjustment winding is connected in series with the beginning of the voltage adjustment winding.

[0036] The series winding is a center-entry type, comprising an upper series winding and a lower series winding connected in parallel.

[0037] The impedance regulating winding is divided into two coils to control the magnetic energy absorbed by the transformer during operation. These coils are connected with opposite magnetic polarities at different tap points, thereby achieving impedance regulation under a given voltage configuration (i.e. without changing the voltage ratio).

[0038] The impedance adjustment winding has three taps, A, B, and C. The impedance adjustment function is achieved by changing the connection position between the end of the common winding and the tap of the impedance adjustment winding.

[0039] When the end of the common winding is connected to tap B of the impedance regulating winding, the transformer impedance is at its minimum; when the end of the common winding is connected to tap A of the impedance regulating winding, the transformer impedance is at its maximum.

[0040] The voltage regulating winding has several taps, and medium-voltage regulation is achieved by changing the position of the taps.

[0041] In one embodiment, a 500kV single-phase autotransformer with a built-in impedance regulating winding includes a series winding, a common winding, an impedance regulating winding, a voltage regulating winding, a low-voltage winding, and a core. The low-voltage winding is located between the core and the impedance regulating coil, the common winding is located between the impedance regulating winding and the series winding, and the voltage regulating winding is located on the outermost side. The winding arrangement diagram is shown below. Figure 1 As shown.

[0042] The end of the series winding is connected in series with the beginning of the common winding, the end of the common winding is connected in series with the beginning of the impedance regulating winding, and the end of the impedance regulating winding is connected in series with the beginning of the voltage regulating winding. The winding connection method is as follows: Figure 2 As shown.

[0043] The series winding is a center-entry type, comprising an upper series winding and a lower series winding connected in parallel.

[0044] The impedance regulating winding is divided into two coils to control the magnetic energy absorbed by the transformer during operation. These coils are connected with opposite magnetic polarities at different tap points, thereby achieving impedance regulation under a given voltage configuration (i.e., without changing the voltage ratio). The impedance regulating winding has three taps A, B, and C. Impedance regulation is achieved by changing the connection position between the end of the common winding and the taps of the impedance regulating winding. Different connection methods are as follows: Figure 3 As shown.

[0045] When the end of the common winding is connected to tap B of the impedance regulating winding, the transformer impedance is at its minimum of 21.61%; when the end of the common winding is connected to tap A of the impedance regulating winding, the transformer impedance is at its maximum of 41.66%; and when the end of the common winding is connected to tap C of the impedance regulating winding, the transformer impedance is 38.73%. The voltage regulating winding has several taps, and medium-voltage regulation is achieved by changing the position of the taps.

[0046] Furthermore, in this invention, the low-voltage winding is located between the core and the impedance regulating winding, the common winding is located between the impedance regulating winding and the series winding, and the voltage regulating winding is located on the outermost side. This concentric winding arrangement optimizes the electromagnetic field distribution, rationally allocates the ampere-turn balance among the windings, reduces leakage flux, and improves electromagnetic coupling efficiency. It ensures insulation reliability at high voltage levels (500kV) and reduces the risk of partial discharge; simultaneously, it provides a good magnetic coupling environment for the impedance regulating winding, improving impedance regulation sensitivity and linearity.

[0047] The series winding is a center-entry type, consisting of parallel upper and lower series windings. The center-entry design allows for symmetrical current distribution in the upper and lower windings, reducing axial electrodynamic forces and improving short-circuit mechanical strength. This enhances the transformer's short-circuit withstand capability and strengthens operational safety, making it particularly suitable for large-capacity, high-voltage 500kV autotransformers, effectively suppressing winding deformation caused by short-circuit faults.

[0048] The impedance adjustment winding is divided into two coils and has three taps A, B, and C, as follows: Figure 2As shown, the common winding end is connected to tap A of the impedance regulating winding. By segmenting the impedance regulating winding and setting multiple connection points, a switchable magnetic circuit path is formed, changing the effective number of winding turns and leakage magnetic path participating in the main magnetic flux coupling. This achieves step-wise adjustment of the short-circuit impedance (e.g., 21.61%~41.66%), meeting the impedance matching requirements under different main transformer operating conditions and improving the universal adaptability of the spare phase. The two impedance regulating coils are connected with opposite magnetic polarities at different tap points. The opposite polarity connection causes the leakage magnetic flux generated by the two coils to be in opposite directions, and the overall leakage magnetic flux can be controlled through magnetic flux cancellation or superposition effects. Without changing the main transformer voltage ratio, the equivalent leakage reactance can be significantly changed simply by switching the connection points, achieving "pure impedance regulation," avoiding voltage fluctuations, and ensuring stable system operation.

[0049] Impedance adjustment is achieved by connecting the end of the common winding to different taps (A / B / C) of the impedance regulating winding, such as... Figure 3 The diagram shows three different connection methods. Tap switching alters the number of turns and magnetomotive force distribution in the actual current-carrying portion of the impedance regulating winding, thereby adjusting the transformer's equivalent short-circuit impedance. For example... Figure 3 As shown, when tap A is connected, all impedance regulating windings are engaged, resulting in maximum leakage flux and the highest impedance (41.66%). When tap B is connected, some windings are short-circuited or reverse-compensated, resulting in minimum leakage flux and the lowest impedance (21.61%). When tap C is connected, the impedance is in an intermediate state (38.73%), achieving multi-level adjustment. This enables precise, discrete impedance matching, adapting to impedance differences in transformers of different models or service lives.

[0050] The voltage regulating winding is independently set up and has multiple taps for medium-voltage side voltage regulation. This independent voltage regulating winding handles the voltage regulation function, decoupled from the impedance regulation function. This ensures that voltage and impedance regulation do not interfere with each other, allowing for independent adjustment of impedance parameters while maintaining the target voltage output, improving control flexibility and system compatibility. The voltage ratio is not changed during impedance regulation. Regulation is achieved by changing only the leakage reactance without affecting the main flux turns ratio. This avoids output voltage fluctuations caused by impedance regulation, ensuring stable power supply quality and compliance with grid operation standards, making it particularly suitable for voltage-sensitive critical hub substations. As a backup phase, it matches different main transformer impedance parameters. Utilizing adjustable impedance characteristics, one backup transformer can replace multiple faulty phases with different impedance parameters. This significantly reduces the grid's demand for backup transformers, saving equipment investment and storage costs; it also shortens fault recovery time, improving the power system's emergency response capability and power supply reliability. After replacement, impedance regulation ensures the impedance value of the newly engaged phase matches the other two phases. This eliminates three-phase current and voltage imbalances, prevents circulating currents, additional losses, and protection malfunctions, ensures safe load operation of the main transformer, and extends equipment life.

[0051] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0052] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A single-phase autotransformer with a built-in impedance regulating winding, characterized in that, It includes the core, series winding, common winding, voltage regulating winding, low-voltage winding, and impedance regulating winding; The low-voltage winding is positioned between the iron core and the impedance regulating winding; The common winding is positioned between the impedance adjustment winding and the series winding; The voltage regulating winding is located on the outermost side; The end of the series winding is connected to the beginning of the common winding, the end of the common winding is connected to the beginning of the impedance adjustment winding, and the end of the impedance adjustment winding is connected to the beginning of the voltage adjustment winding. The impedance regulating winding includes two coils and is equipped with taps A, B and C. By switching the connection positions of the end of the common winding with different taps of the impedance regulating winding, the short-circuit impedance of the transformer can be adjusted without changing the voltage ratio of the transformer during the impedance adjustment process.

2. The single-phase autotransformer with a built-in impedance regulating winding as described in claim 1, characterized in that, The voltage regulating winding is equipped with multiple taps for independent adjustment of the medium-voltage side voltage.

3. The single-phase autotransformer with a built-in impedance regulating winding as described in claim 1, characterized in that, The series winding has a centrally input structure, including an upper series winding and a lower series winding arranged in parallel.

4. The single-phase autotransformer with a built-in impedance regulating winding as described in claim 1, characterized in that, The two coils in the impedance regulating winding are connected with opposite magnetic polarities under different tap states to control the amount of magnetic energy absorbed during transformer operation and change the leakage flux distribution to achieve impedance regulation.

5. The single-phase autotransformer with a built-in impedance regulating winding as described in claim 1, characterized in that, When the end of the common winding is connected to tap B of the impedance regulating winding, the transformer's short-circuit impedance is at its minimum; when the end of the common winding is connected to tap A of the impedance regulating winding, the transformer's short-circuit impedance is at its maximum; when the end of the common winding is connected to tap C of the impedance regulating winding, the transformer's short-circuit impedance is both smaller than its maximum and larger than its minimum.

6. The single-phase autotransformer with a built-in impedance regulating winding as described in claim 1, characterized in that, By adjusting the taps of the impedance regulating winding and the tap positions of the voltage regulating winding respectively, decoupled control of the transformer impedance parameters and the medium-voltage output voltage can be achieved.

7. The single-phase autotransformer with a built-in impedance regulating winding as described in claim 1, characterized in that, A single-phase autotransformer is used as a spare phase in a phase autotransformer bank. Its impedance value is adjusted to match the original impedance parameters of different operating phases.

8. The single-phase autotransformer with a built-in impedance regulating winding as described in claim 1, characterized in that, The transformer impedance ranges from a minimum of 21.61% to a maximum of 41.66%.

9. The single-phase autotransformer with a built-in impedance regulating winding as described in claim 1, characterized in that, The single-phase autotransformer is a 500kV single-phase autotransformer.

10. The adjustment method of a single-phase autotransformer with a built-in impedance regulating winding as described in any one of claims 1-9, characterized in that, It includes, Detect the original impedance parameters of the transformer in the faulty phase; Switch the end of the common winding of the standby phase transformer to the tap A, tap B or tap C corresponding to the impedance regulating winding so that its short-circuit impedance matches the fault. Adjust the tap position of the voltage regulating winding so that the output voltage on the medium voltage side meets the system operating requirements; The adjusted backup phase is put into operation to replace the faulty phase, thus achieving rapid power restoration.

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