Power conversion system and distribution transformer

Abstract

The invention relates to the technical field of transformers, in particular to a power conversion system and a distribution transformer, and the power conversion system comprises a transformer body and a plurality of converter modules; the transformer body comprises a main transformer module and a series transformer module; the main transformer module comprises a middle iron yoke, a lower iron yoke and a plurality of first iron core columns; the series transformer module comprises an upper iron yoke and a plurality of second iron core columns; the compensation current output end is electrically connected with the first low-voltage winding, the compensation voltage output end is electrically connected with the second low-voltage winding, and the first high-voltage winding and the second high-voltage winding are connected in series. The power distribution transformer is complete in magnetic circuit, reasonable in structure, low in system loss, high in stability and reliability and capable of achieving regulation and control over the power grid high-voltage side current and the power grid low-voltage side load voltage, and the problems that according to an existing power distribution transformer fusion electronic power technology, the fusion degree is not high, products have many defects, and the stability and the reliability of the products are poor are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and in particular to a power conversion system and a distribution transformer. Background Art

[0002] With the acceleration of urbanization and the improvement of residents' living standards, the demand for electricity is growing, and the power grid is also constantly improving. Distribution transformers are key equipment for power grid supply, which can convert high-voltage electricity in the transmission system into low-voltage electricity to meet the needs of various electrical equipment. In recent years, the development trend of smart grids has put forward new requirements for the performance of distribution transformers, such as requiring the use of highly intelligent, energy-efficient, highly safe and highly reliable distribution transformers; requiring distribution transformers to have adaptive adjustment functions, data collection and analysis functions, etc.

[0003] The distribution transformer combined with electronic power technology is a current research hotspot, but the technical integration of the two is still not high enough, and the product has many defects, such as large no-load loss, large core consumption, and increased resistance loss and leakage due to the large number of windings, which cannot improve the performance of the distribution transformer. The product has poor stability and low reliability in practical applications. In addition, the overall system currently has problems such as high manufacturing cost, large space occupation and low product applicability. Summary of the invention

[0004] The main purpose of the present invention is to provide a power conversion system with a complete magnetic circuit, a small structural space occupation, a reasonable structure, low system loss, and high stability and reliability. It can realize the regulation of the current on the high-voltage side of the power grid and the load voltage on the low-voltage side of the power grid, and solves the problem that the current distribution transformer has a low degree of integration of electronic power technology and there are many defects in the product, resulting in poor stability and low reliability of the product in practical applications.

[0005] Another object of the present invention is to provide a distribution transformer using the above power conversion system, which has the characteristics of low loss, low cost, small structure volume, reasonable and compact structure, high product stability and reliability. It solves the problem that the current distribution transformer has a low degree of integration of electronic power technology, and the product has many defects, resulting in poor stability and low reliability of the product in practical applications.

[0006] To achieve the above-mentioned purpose, the power conversion system proposed in the present invention is applied to a distribution transformer, comprising a transformer body and a plurality of converter modules; The transformer body includes a main transformer module and a series transformer module; The main transformer module comprises a middle iron yoke, a lower iron yoke and a plurality of first iron core columns, each of which is sequentially provided with a first low-voltage winding and a first high-voltage winding outward; two ends of the first iron core column are respectively connected to the middle iron yoke and the lower iron yoke; The series transformer module comprises an upper iron yoke and a plurality of second iron core columns, each of which is sequentially provided with a second low-voltage winding and a second high-voltage winding outward; two ends of the second iron core column are respectively connected to the upper iron yoke and the middle iron yoke, and the second iron core column is arranged in one-to-one correspondence with the first iron core column; The converter module has a compensation current output terminal and a compensation voltage output terminal. The compensation current output terminal is electrically connected to the first low-voltage winding to adjust the current of the first low-voltage winding. The compensation voltage output terminal is electrically connected to the second low-voltage winding to adjust the voltage of the second low-voltage winding. The first high-voltage winding and the second high-voltage winding are connected in series.

[0007] Optionally, the converter module includes a first converter, a second converter and a DC bus, the compensation current output end of the first converter is connected to the first low-voltage winding, the compensation voltage output end of the second converter is connected to the second low-voltage winding, and the DC input end of the first converter and the DC input end of the second converter are respectively connected to the DC bus.

[0008] Optionally, both the first converter and the second converter are voltage source PWM converters.

[0009] Optionally, the first core column, the second core column, the upper iron yoke, the middle iron yoke and the lower iron yoke are fixed by through-hole screws.

[0010] Optionally, the number of the first core legs is 3, and the number of the second core legs is 3; The three first core columns are circumferentially distributed at the lower end of the middle iron yoke, and the three second core columns are circumferentially distributed at the upper end of the middle iron yoke; The three first core legs have the same height, and the three second core legs have the same height.

[0011] Optionally, the centers of the cross sections of the three first core columns form an equilateral triangle, and the centers of the cross sections of the three second core columns form another equilateral triangle; the shapes of the upper iron yoke, the middle iron yoke and the lower iron yoke are all equilateral triangles.

[0012] Optionally, the first core column and the second core column are respectively formed by stacking a plurality of silicon steel sheets; the upper iron yoke, the middle iron yoke and the lower iron yoke are respectively formed by winding amorphous strips.

[0013] Optionally, the ends of the first low-voltage winding and the first high-voltage winding in the height direction are flush, and the ends of the second low-voltage winding and the second high-voltage winding in the height direction are flush.

[0014] The present invention also provides a distribution transformer using any of the above-mentioned power conversion systems.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. In the power conversion system of the present invention, the transformer body includes a main transformer module and a series transformer module. The two ends of the first core column are respectively connected to the middle iron yoke and the lower iron yoke, and the two ends of the second core column are respectively connected to the upper iron yoke and the middle iron yoke, and the second core column is arranged one-to-one with the first core column. The main transformer module and the series transformer module share the middle iron yoke to form a complete magnetic circuit with low core consumption. The first core column and the second core column are arranged one-to-one. The system is arranged axially as a whole, and the structure occupies a small space, thereby improving space utilization. The main transformer module of the present invention uses only two windings, has a reasonable and compact structure, low copper consumption, and low loss, stability and reliability of the power conversion system, thereby improving the overall performance of the distribution transformer. It solves the problem that the current distribution transformer has a low degree of integration of electronic power technology, and there are many defects in the product, resulting in poor stability and low reliability of the product in practical applications.

[0016] 2. The converter module has a compensation current output terminal and a compensation voltage output terminal, the compensation current output terminal is electrically connected to the first low-voltage winding, the compensation voltage output terminal is electrically connected to the second low-voltage winding, and the first high-voltage winding and the second high-voltage winding are connected in series. When harmonics, reactive power, and asymmetric components appear in the load current on the low-voltage side of the power grid, the corresponding compensation current is generated by the converter module and output to the first low-voltage winding by means of the magnetomotive force balance principle of the transformer, so that the current on the high-voltage side of the power grid is always controlled to be a symmetrical sine wave, and the grid side is always close to the unity power factor. When the voltage on the high-voltage side of the power grid fluctuates, is asymmetric, etc., the corresponding compensation voltage is generated by the converter module and output to the second low-voltage winding, so that the voltage of the second high-voltage winding changes accordingly. Since the second high-voltage winding is connected in series with the first high-voltage winding in the high-voltage side of the power grid, the voltage of the first high-voltage winding is stabilized by the voltage change of the second high-voltage winding, so as to achieve the stability of the first low-voltage winding, thereby offsetting the fluctuation and asymmetric components in the voltage on the high-voltage side of the power grid, and finally stabilizing the voltage of each winding of the main transformer module and the load voltage on the low-voltage side of the power grid at the rated value. Therefore, the power conversion system of the present invention realizes the regulation of the current on the high-voltage side of the power grid and the load voltage on the low-voltage side of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a power conversion system according to an embodiment of the present invention; Figure 2 A circuit topology of a power conversion system according to an embodiment of the present invention; Figure 3 A top view of a power conversion system according to an embodiment of the present invention; Figure 4 for Figure 3 Cross-sectional view along CC.

[0018] Among them: 1. Transformer body; 11. Main transformer module; 111. Middle iron yoke; 112. Lower iron yoke; 113. First iron core column; 113a. First low-voltage winding; 113b. First high-voltage winding; 12. Series transformer module; 121. Upper iron yoke; 122. Second iron core column; 122a. Second low-voltage winding; 122b. Second high-voltage winding; 2. Converter module; 21. First converter; 22. Second converter. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0021] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text is to include three parallel solutions. Taking "A and / or B as an example", it includes solution A, or solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] The invention provides a power conversion system.

[0024] In the embodiment of the present invention, Figures 1 to 4 As shown, the power conversion system is applied to a distribution transformer, including a transformer body 1 and a plurality of converter modules 2; The transformer body 1 includes a main transformer module 11 and a series transformer module 12; The main transformer module 11 includes a middle iron yoke 111, a lower iron yoke 112 and a plurality of first iron core columns 113, each of which is sequentially provided with a first low-voltage winding 113a and a first high-voltage winding 113b outwardly; two ends of the first iron core column 113 are respectively connected to the middle iron yoke 111 and the lower iron yoke 112; The series transformer module 12 includes an upper iron yoke 121 and a plurality of second iron core columns 122, each of which is sequentially provided with a second low-voltage winding 122a and a second high-voltage winding 122b outward; the two ends of the second iron core column 122 are respectively connected to the upper iron yoke 121 and the middle iron yoke 111, and the second iron core column 122 is arranged one by one with the first iron core column 113; The converter module 2 has a compensation current output terminal and a compensation voltage output terminal. The compensation current output terminal is electrically connected to the first low-voltage winding 113a to adjust the current of the first low-voltage winding 113a. The compensation voltage output terminal is electrically connected to the second low-voltage winding 122a to adjust the voltage of the second low-voltage winding 122a. The first high-voltage winding 113b and the second high-voltage winding 122b are connected in series.

[0025] The transformer body 1 in the power conversion system of the present invention includes a main transformer module 11 and a series transformer module 12, the two ends of the first core column 113 are respectively connected to the middle iron yoke 111 and the lower iron yoke 112, the two ends of the second core column 122 are respectively connected to the upper iron yoke 121 and the middle iron yoke 111, and the second core column 122 is arranged one-to-one with the first core column 113, and the main transformer module 11 and the series transformer module 12 share the middle iron yoke 111 to form a complete magnetic circuit, low iron core consumption, and the first core column 113 and the second core column 122 are arranged one-to-one. The system is arranged axially as a whole, the structure occupies a small space, and the space utilization rate is improved. The main transformer module 11 of the present invention uses only two windings, has a reasonable and compact structure, low copper consumption, and the power conversion system has low loss, high stability and reliability, thereby improving the overall performance of the distribution transformer. It solves the problem that the current distribution transformer has a low degree of integration of electronic power technology, and there are many defects in the product, resulting in poor stability and low reliability of the product in practical applications.

[0026] The converter module 2 has a compensation current output terminal and a compensation voltage output terminal. The compensation current output terminal is electrically connected to the first low-voltage winding 113a to adjust the current of the first low-voltage winding 113a. The compensation voltage output terminal is electrically connected to the second low-voltage winding 122a to adjust the voltage of the second low-voltage winding 122a. The first high-voltage winding 113b and the second high-voltage winding 122b are connected in series. When harmonics, reactive power, and asymmetric components appear in the load current on the low-voltage side of the power grid, the corresponding compensation current is generated by the converter module 2 and output to the first low-voltage winding 113a by means of the magnetomotive force balance principle of the transformer, so that the current on the high-voltage side of the power grid is always controlled to be a symmetrical sine wave, and the power factor on the grid side is always close to unity. When the voltage on the high-voltage side of the power grid fluctuates or is asymmetric, the corresponding compensation voltage is generated by the converter module 2 and output to the second low-voltage winding 122a, so that the voltage of the second high-voltage winding 122b changes accordingly. Since the second high-voltage winding 122b is connected in series with the first high-voltage winding 113b in the high-voltage side of the power grid, the voltage of the first high-voltage winding 113b is stabilized by the voltage change of the second high-voltage winding 122b, and the stability of the first low-voltage winding 113a is achieved, thereby offsetting the fluctuation and asymmetric components in the voltage on the high-voltage side of the power grid, and finally stabilizing the voltage of each winding of the main transformer module 11 and the load voltage on the low-voltage side of the power grid at the rated value. Therefore, the power conversion system of the present invention realizes the regulation of the current on the high-voltage side of the power grid and the load voltage on the low-voltage side of the power grid.

[0027] Specifically, the converter module 2 is arranged in parallel with the output side of the first low-voltage winding 113 a.

[0028] Specifically, the first low-voltage winding 113a is connected to the low-voltage side load of the power grid and supplies power to the low-voltage side load of the power grid, and the first high-voltage winding 113b and the second high-voltage winding 122b are connected in series and connected to the high-voltage side of the power grid as a whole.

[0029] like Figure 2 As shown, in one embodiment of the present application, the converter module 2 includes a first converter 21, a second converter 22 and a DC bus, the compensation current output terminal of the first converter 21 is connected to the first low-voltage winding 113a, the compensation voltage output terminal of the second converter 22 is connected to the second low-voltage winding 122a, and the DC input terminal of the first converter 21 and the DC input terminal of the second converter 22 are respectively connected to the DC bus.

[0030] The converter module 2 includes a first converter 21 and a second converter 22. The compensation current output terminal of the first converter 21 is connected to the first low-voltage winding 113a, and the compensation voltage output terminal of the second converter 22 is connected to the second low-voltage winding 122a. The two converters independently process the electric energy of two different low-voltage windings, so that the system can more flexibly respond to different load requirements and power quality requirements. The DC input terminal of the first converter 21 and the DC input terminal of the second converter 22 are respectively connected to the DC bus. Through such a connection method, the energy loss in the power conversion process can be reduced, a stable power supply environment can be provided, and the stability and reliability of the entire system can be improved; in addition, the system structure can be simplified and the production cost can be reduced.

[0031] In an embodiment of the present application, the first converter 21 and the second converter 22 are both voltage source PWM converters.

[0032] By adopting a voltage source PWM converter, the output voltage and current can be accurately controlled to achieve efficient power conversion. At the same time, it can also effectively suppress low-order harmonics, reduce harmonic pollution to the power grid, and improve the power quality of the power conversion system.

[0033] In one embodiment of the present application, the first core column 113 , the second core column 122 , the upper iron yoke 121 , the middle iron yoke 111 and the lower iron yoke 112 are fixed by through-hole screws.

[0034] The first core column 113, the second core column 122, the upper iron yoke 121, the middle iron yoke 111 and the lower iron yoke 112 are connected by through-screws and fixed tightly together, thereby effectively improving the structural stability of the product and preventing displacement or deformation during operation.

[0035] Of course, according to actual conditions, the first core column 113, the second core column 122, the upper iron yoke 121, the middle iron yoke 111 and the lower iron yoke 112 can be fixed in combination with other limiting structures. For example, clamps can be respectively arranged on the outer sides of the upper iron yoke 121, the middle iron yoke 111 and the lower iron yoke 112 along the length direction of the iron yoke, and the clamps in the same iron yoke can be connected with bolts and nuts.

[0036] like Figure 1 , 3 As shown in FIG. 4 , in one embodiment of the present application, the number of first core legs 113 is 3, and the number of second core legs 122 is 3; The three first core columns 113 are circumferentially distributed at the lower end of the middle iron yoke 111 , and the three second core columns 122 are circumferentially distributed at the upper end of the middle iron yoke 111 ; The three first core legs 113 have the same height, and the three second core legs 122 have the same height.

[0037] Since the number of the first core columns 113 and the number of the second core columns 122 are the same, the three first core columns 113 are distributed circumferentially at the lower end of the middle iron yoke 111, and the three second core columns 122 are distributed circumferentially at the upper end of the middle iron yoke 111, and the three first core columns 113 have the same height, and the three second core columns 122 have the same height. In this way, when the first core columns 113 and the second core columns 122 are arranged one by one, the overall structure of the power conversion system is more aesthetically pleasing.

[0038] like Figure 1 As shown, in one embodiment of the present application, the centers of the cross sections of the three first core columns 113 form an equilateral triangle, and the centers of the cross sections of the three second core columns 122 form another equilateral triangle; the shapes of the upper iron yoke 121, the middle iron yoke 111 and the lower iron yoke 112 are all equilateral triangles.

[0039] The centers of the cross sections of the three first core columns 113 form an equilateral triangle, which can make the three-phase magnetic circuit of the main transformer module 11 symmetrical; the centers of the cross sections of the three second core columns 122 form another equilateral triangle, which can make the three-phase magnetic circuit of the series transformer module 12 symmetrical, and the shapes of the upper iron yoke 121, the middle iron yoke 111 and the lower iron yoke 112 are all equilateral triangles. At this time, the transformer body 1 forms a "pin"-shaped structure, and the magnetic resistance of the three-phase magnetic circuit of both the main transformer module 11 and the series transformer module 12 is equal, and the no-load current is balanced, so that the magnetic flux distribution in each phase winding of the main transformer module 11 and the series transformer module 12 can be uniform, so that the waveforms of the induced electromotive force of both the main transformer module 11 and the series transformer module 12 are closer to the sine wave, which helps to reduce the energy loss of both, and thus improve the overall stability and reliability of the system.

[0040] In one embodiment of the present application, the first core column 113 and the second core column 122 are respectively formed by stacking a number of silicon steel sheets; the upper iron yoke 121, the middle iron yoke 111 and the lower iron yoke 112 are respectively formed by winding amorphous strips.

[0041] Silicon steel sheets have excellent magnetic conductivity and are also helpful in reducing eddy current losses, thereby improving the efficiency of the main transformer module 11 and the series transformer module 12, and ensuring stable operation of both. Amorphous materials have excellent properties such as high magnetic permeability and low loss. The upper iron yoke 121, the middle iron yoke 111, and the lower iron yoke 112 are wound with amorphous strips, which can effectively reduce the losses of the main transformer module 11 and the series transformer module 12, such as reducing no-load losses, so that the main transformer module 11 and the series transformer module 12 have the characteristics of low loss and high stability, and can also reduce manufacturing costs.

[0042] In one embodiment of the present invention, the magnetic flux of the yoke is 1 / √3 (0.577 times) of the column magnetic flux. The present invention can utilize the low loss performance of the amorphous material while avoiding the amorphous material from reaching the saturation magnetic induction density state, so that the upper iron yoke 121, the middle iron yoke 111 and the lower iron yoke 112 have low loss performance and maintain a low loss state; in addition, it can also improve the column magnetic density and filling rate while reducing material consumption under the same loss conditions.

[0043] Preferably, the first core column 113 and the second core column 122 are made of high-grade silicon steel sheets stacked into a circle, and the coil is directly wound on the core column. The main transformer module 11 and the series transformer module 12 have high filling performance and high short-circuit resistance.

[0044] like Figure 4 As shown, in one embodiment of the present application, the ends of the first low voltage winding 113a and the first high voltage winding 113b in the height direction are flush, and the ends of the second low voltage winding 122a and the second high voltage winding 122b in the height direction are flush.

[0045] The ends of the first low-voltage winding 113a and the first high-voltage winding 113b are flush in height direction, and the ends of the second low-voltage winding 122a and the second high-voltage winding 122b are flush in height direction. This helps to reduce electromagnetic interference and leakage caused by irregular arrangement of windings, improve the electrical performance of the system, and make the system look neater and more beautiful.

[0046] Specifically, the first low voltage winding 113a is sleeved on the first core column 113 and distributed along the axial direction of the first core column 113, the first high voltage winding 113b is wound on the side of the first low voltage winding 113a away from the first core column 113, and a gap is provided between the first high voltage winding 113b and the first low voltage winding 113a. The second low voltage winding 122a and the second high voltage winding 122b are wound in the same manner.

[0047] The present invention also provides a distribution transformer using the above power conversion system.

[0048] By using the above-mentioned power conversion system, the distribution transformer has the characteristics of low loss, low cost, small structure volume, reasonable and compact structure, high product stability and reliability. It solves the problem that the current distribution transformer is not integrated with electronic power technology to a high degree, and the product has many defects, resulting in poor stability and low reliability of the product in practical applications.

[0049] In one embodiment of the present invention, the distribution transformer of the present invention can be used to adjust the voltage within the range of -20%-20% of the rated voltage, the reactive power compensation capability can reach 30% of the rated capacity of the main transformer module 11, the three-phase unbalance compensation capability can reach 30% of the current of the converter module 2, the voltage regulation response capability is <20ms, and the current compensation response capability is <20ms.

[0050] The working process of the power conversion system of the present invention is as follows: The main transformer module 11 and the series transformer module 12 include phases A, B, and C respectively. Figure 2 , taking the A phase of the main transformer module 11 and the A phase of the series transformer module 12 as examples: the A phase winding of the main transformer module 11 includes the A phase first high voltage winding 113b and the A phase first low voltage winding 113a, wherein the first / end terminals of the A phase first high voltage winding 113b are A / A1, and the first / end terminals of the A phase first low voltage winding 113a are a / a1; the A phase winding of the series transformer module 12 includes the A phase second high voltage winding 122b and the A phase second low voltage winding 122a, wherein the first / end terminals of the A phase second high voltage winding 122b are A2 / X, and the first / end terminals of the A phase second low voltage winding 122a are a2 / x. The compensation current output terminal of the converter module 2 is electrically connected to the A phase first low voltage winding 113a, and the compensation voltage output terminal is electrically connected to the A phase second low voltage winding 122a. The first / last terminal a / a1 of the first low-voltage winding 113a of phase A are respectively connected to the load on the low-voltage side of the power grid, the terminal A1 of the first high-voltage winding 113b of phase A and the first terminal A2 of the second high-voltage winding 122b of phase A are connected in series, and the first terminal A of the first high-voltage winding 113b of phase A and the terminal X of the second high-voltage winding 122b of phase A are respectively connected to the high-voltage side of the power grid. The main transformer module 11 is monitored and sampled. When harmonics, reactive power, and asymmetric components appear in the load current on the low-voltage side of the power grid, the converter module 2 generates a corresponding compensation current and outputs it to the first low-voltage winding 113a of phase A, thereby regulating the current on the high-voltage side of the power grid. When the voltage on the high-voltage side of the power grid fluctuates or becomes asymmetric, the converter module 2 generates a corresponding compensation voltage and outputs it to the second low-voltage winding 122a of phase A, causing the voltage of the second high-voltage winding 122b of phase A to change accordingly, thereby further stabilizing the voltage of the first high-voltage winding 113b, and thus stabilizing the voltage of each winding of the main transformer module 11 and the load voltage on the low-voltage side of the power grid at the rated value.

[0051] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A power conversion system, applied to a distribution transformer, characterized in that: It includes a transformer body and several converter modules; The transformer body includes a main transformer module and a series transformer module; The main transformer module comprises a middle iron yoke, a lower iron yoke and a plurality of first iron core columns, each of which is sequentially provided with a first low-voltage winding and a first high-voltage winding outward; two ends of the first iron core column are respectively connected to the middle iron yoke and the lower iron yoke; The series transformer module comprises an upper iron yoke and a plurality of second iron core columns, each of which is sequentially provided with a second low-voltage winding and a second high-voltage winding outward; two ends of the second iron core column are respectively connected to the upper iron yoke and the middle iron yoke, and the second iron core column is arranged in one-to-one correspondence with the first iron core column; The converter module has a compensation current output terminal and a compensation voltage output terminal. The compensation current output terminal is electrically connected to the first low-voltage winding to adjust the current of the first low-voltage winding. The compensation voltage output terminal is electrically connected to the second low-voltage winding to adjust the voltage of the second low-voltage winding. The first high-voltage winding and the second high-voltage winding are connected in series.

2. The power conversion system according to claim 1, characterized in that: The converter module includes a first converter, a second converter and a DC bus, the compensation current output end of the first converter is connected to the first low-voltage winding, the compensation voltage output end of the second converter is connected to the second low-voltage winding, and the DC input end of the first converter and the DC input end of the second converter are respectively connected to the DC bus.

3. The power conversion system according to claim 2, characterized in that: The first converter and the second converter are both voltage source PWM converters.

4. The power conversion system according to claim 1, characterized in that: The first core column, the second core column, the upper iron yoke, the middle iron yoke and the lower iron yoke are fixed by through-core screws.

5. The power conversion system according to claim 1, characterized in that: The number of the first core legs is 3, and the number of the second core legs is 3; The three first core columns are circumferentially distributed at the lower end of the middle iron yoke, and the three second core columns are circumferentially distributed at the upper end of the middle iron yoke; The three first core legs have the same height, and the three second core legs have the same height.

6. The power conversion system according to claim 5, characterized in that: The centers of the cross sections of the three first core columns form an equilateral triangle, and the centers of the cross sections of the three second core columns form another equilateral triangle; the shapes of the upper iron yoke, the middle iron yoke and the lower iron yoke are all equilateral triangles.

7. The power conversion system according to claim 1, characterized in that: The first core column and the second core column are respectively formed by stacking a plurality of silicon steel sheets; the upper iron yoke, the middle iron yoke and the lower iron yoke are respectively formed by winding amorphous strips.

8. The power conversion system according to claim 1, characterized in that: The ends of the first low-voltage winding and the first high-voltage winding in the height direction are flush with each other, and the ends of the second low-voltage winding and the second high-voltage winding in the height direction are flush with each other.

9. A distribution transformer, characterized in that: Use the power conversion system as claimed in any one of claims 1 to 8.

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