Magnetic integrated hybrid distribution transformer

Abstract

A magnetic integrated hybrid distribution transformer includes a main transformer, a series isolation transformer and a converter, wherein: an iron core includes an iron beam unit, an iron yoke unit and a leakage magnetic core unit. The main transformer includes secondary windings, primary windings and control windings all of which are layer-windings and wound around main transformer iron beams. The series isolation transformer includes converter side windings and grid side windings all of which are pancake-windings and wound around isolation transformer iron beams. The converter side windings and the control windings are respectively connected with the converter by the star connection with neutral point. Leakage magnetic cores are respectively inserted between the primary windings and the control windings or between the converter side windings and the grid side windings, so as to achieve magnetic integration design of the transformer and output connection inductor of the converter.

Claims

1. A magnetic integrated hybrid distribution transformer, comprising an iron core, windings and a converter (22), wherein: the iron core comprises an iron beam unit, an iron yoke unit and a leakage magnetic core unit; the iron beam unit comprises three main transformer iron beams and three isolation transformer iron beams that connect with each other sequentially; the iron yoke unit comprises a bottom iron yoke (17), a middle iron yoke (16) and four connection iron yokes; the leakage magnetic core unit comprises four control winding leakage magnetic cores and three converter side winding leakage magnetic cores; the windings comprise main transformer windings and series isolation transformer windings; in each phase, the main transformer windings are a control winding, a primary winding and a secondary winding all of which are wrapped around a corresponding main transformer iron beam; in each phase, the series isolation transformer windings are a grid side winding and a converter winding both of which are wrapped around a corresponding isolation transformer iron beam; each main transformer iron beam connects to the bottom iron yoke (17) and the middle iron yoke (16); each connection iron yoke connects to the middle iron yoke (16) and an end of the corresponding series isolation transformer iron beam; the main transformer iron beams and the isolation transformer iron beams form two main transformer windows and three series isolation transformer windows by sharing the middle iron yoke (16); the control winding leakage magnetic cores are respectively inserted between primary windings and control windings within two main transformer windows; the converter side winding leakage magnetic cores are respectively inserted between converter side windings and grid side windings within the three series isolation transformer windows; the converter (22) connects to the control windings and converter side windings.

2. The magnetic integrated hybrid distribution transformer, as recited in claim 1, wherein: in each phase, the primary winding connects with the grid side winding in series, grid side windings connect to a power network by a star connection with neutral point; secondary windings supply load by a three-phase four-wire methods; in each phase, the control winding and the converter side winding connect to the converter (22) by the star connection with neutral point.

3. The magnetic integrated hybrid distribution transformer, as recited in claim 1, wherein: the converter (22) comprises current bridge arms, voltage bridge arms, a zero sequence bridge arm and a DC-link (direct current-link) capacitor all of which connect with each other in parallel, the control windings are respectively connected with middle points of the current bridge arms, the converter side windings are respectively connected with middle points of the voltage bridge arms, end points of control windings and converter side windings connect to a middle point of the zero sequence bridge arm.

4. The magnetic integrated hybrid distribution transformer, as recited in claim 1, wherein: the secondary winding, the primary winding and the control winding in each phase are layer-windings all of which are concentrically wound around the corresponding main transformer iron beam from inside to outside; the converter side winding and the grid side winding in each phase are pancake windings both of which are concentrically wound around the corresponding phase isolation transformer iron beam from left to right.

5. The magnetic integrated hybrid distribution transformer, as recited in claim 1, wherein: a bottom end of the main transformer iron beams connects to the bottom iron yoke (17), an upper end of the main transformer iron beams connects to the middle iron yoke (16); ends of the isolation transformer iron beams connect to an upper end of the four connection iron yokes in sequence, two adjacent isolation transformer iron beams share a common connection iron yoke, and a bottom end of the four connection iron yokes connects to the middle iron yoke (16).

6. The magnetic integrated hybrid distribution transformer, as recited in claim 1, wherein: a phase shift arrangement is adopted in the main transformer windings and the series isolation transformer windings.

7. The magnetic integrated hybrid distribution transformer, as recited in claim 6, wherein: the main transformer windings are respectively arranged on three main transformer iron beams as an order of Phase-A, Phase-B and Phase-C from left to right, the series isolation transformer windings are respectively arranged on three isolation transformer iron beams as an order of Phase-C, Phase-B and Phase-A from left to right.

8. The magnetic integrated hybrid distribution transformer, as recited in claim 1, wherein: each iron yoke is in 45-degree connection with a corresponding iron beam, lamination of the main transformer iron beams is larger than that of the isolation transformer iron beams, and lamination of the bottom iron yoke (17) and the middle iron yoke (16) is larger than that of the connection iron yokes.

9. The magnetic integrated hybrid distribution transformer, as recited in claim 8, wherein: the lamination of the iron core is a silicon steel sheet.

10. The magnetic integrated hybrid distribution transformer, as recited in claim 1, wherein: air gaps between the control winding leakage magnetic core and one of the middle iron yoke (16) and the bottom iron yoke (17) or between the converter side winding leakage magnetic core and one of the middle iron yoke (16) and the isolation transformer iron beam are adjustable; the control windings are elliptic or semi-elliptic.

11. The magnetic integrated hybrid distribution transformer, as recited in claim 2, wherein: the converter (22) comprises current bridge arms, voltage bridge arms, a zero sequence bridge arm and a DC-link (direct current-link) capacitor all of which connect with each other in parallel, the control windings are respectively connected with middle points of the current bridge arms, the converter side windings are respectively connected with middle points of the voltage bridge arms, end points of control windings and converter side windings connect to a middle point of the zero sequence bridge arm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1(a) is a schematic diagram of circuit topology and connection relationship of a main transformer and a series isolation transformer of a magnetic integrated hybrid distribution transformer provided by the present invention.

(2) FIG. 1(b) is a schematic diagram of circuit topology and connection relationship of a converter of the magnetic integrated hybrid distribution transformer provided by the present invention.

(3) FIG. 1(c) is a schematic diagram of circuit topology and connection relationship of a filter of the magnetic integrated hybrid distribution transformer provided by the present invention.

(4) FIG. 2 is a schematic diagram of winding arrangement and a connection method of iron core lamination of the magnetic integrated hybrid distribution transformer provided by the present invention.

(5) FIG. 3 is a three-dimensional schematic diagram of the magnetic integrated hybrid distribution transformer provided by the present invention.

(6) FIG. 4(a) is a main view of the magnetic integrated hybrid distribution transformer provided by the present invention.

(7) FIG. 4(b) is a right view of the magnetic integrated hybrid distribution transformer provided by the present invention.

(8) FIG. 4(c) is a top view of the magnetic integrated hybrid distribution transformer provided by the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(9) The present invention is further described according to the schematic diagrams as follows. It should be understood that the schematic diagrams described herein are merely illustrative for the present invention and are not intended to limit the present invention.

(10) Referring to FIG. 1, the main parts of the magnetic integrated hybrid distribution transformer in this present invention is illustrated. Specifically, the magnetic integrated hybrid distribution transformer comprises a main transformer 20, a series isolation transformer 21, a converter 22 and a filter 32. As shown in FIG. 1(a), the main transformer 20 comprises a phase-A primary winding 1a, a phase-B primary winding 1b, a phase-C primary winding 1c, a phase-A secondary winding 2a, a phase-B secondary winding 2b, a phase-C secondary winding 2c, a phase-A control winding 3a, a phase-B control winding 3b and a phase-C control winding 3c. A beginning terminal and an end terminal of the phase-A primary winding are denoted as A and X, respectively. A beginning terminal and an end terminal of the phase-B primary winding are denoted as B and Y, respectively. A beginning terminal and an end terminal of the phase-C primary winding are denoted as C and Z, respectively. A beginning terminal and an end terminal of the phase-A secondary winding are denoted as a.sub.2 and x.sub.2, respectively. A beginning terminal and an end terminal of the Phase-B secondary winding are respectively denoted as b.sub.2 and y.sub.2. A beginning terminal and an end terminal of phase-C secondary winding are denoted as c.sub.2 and z.sub.2, respectively. A beginning terminal and an end terminal of the Phase-A control winding are denoted as a.sub.3 and x.sub.3, respectively. A beginning terminal and an end terminal of the Phase-B control winding are denoted as b.sub.3 and y.sub.3, respectively. A beginning terminal and an end terminal of the Phase-C control winding are denoted as c.sub.3 and z.sub.3, respectively. The series isolation transformer 21 comprises a Phase-A grid side winding 5a, a Phase-B grid side winding 5b, a Phase-C grid side winding 5c, a Phase-A converter side winding 4a, a Phase-B converter side winding 4b and a Phase-C converter side winding 4c. A beginning terminal and an end terminal of the Phase-A grid side winding are denoted as a.sub.5 and x.sub.5, respectively. A beginning terminal and an end terminal of the Phase-B grid side winding are denoted as b.sub.5 and y.sub.5, respectively. A beginning terminal and an end terminal of the Phase-C grid side winding are denoted as c.sub.5 and z.sub.5, respectively. A beginning terminal and an end terminal of the Phase-A converter side winding are denoted as a.sub.4 and x.sub.4, respectively. a beginning terminal and an end terminal of the Phase-B converter side winding are denoted as b.sub.4 and y.sub.4, respectively. A beginning terminal and an end terminal of the Phase-C converter side winding are denoted as c.sub.4 and z.sub.4, respectively. The primary winding connects with the grid side winding in series, and then connects to a power network by a star-connection with neutral point. Specifically, the beginning terminals A, B and C of the Phase-A primary winding 1a, the Phase-B primary winding 1b and the Phase-C primary winding 1c connect to the power network, while the end terminals X, Y and Z of the Phase-A primary winding 1a, the Phase-B primary winding 1b and the Phase-C primary winding 1c connect to the beginning terminals a.sub.5, b.sub.5 and c.sub.5 of the Phase-A grid side winding 5a, the Phase-B grid side winding 5b and the Phase-C grid side winding 5c, respectively. The end terminals x.sub.5, y.sub.5 and z.sub.5 of the Phase-A grid side winding 5a, the Phase-B grid side winding 5b and the Phase-C grid side winding 5c connect together and form a neutral point.

(11) As shown in FIG. 1(b), the converter 22 comprises a three-phase current bridge arm unit 23 (which is formed by three bridge arms connected with each other in parallel), a three-phase voltage bridge arm unit 24 (which is formed by another three bridge arms connected with each other in parallel), a zero sequence bridge arm 29 and a DC-link capacitor 25. All bridge arms connect to the DC-link capacitor 25 in parallel. Each bridge arm of the three-phase current bridge arm unit 23 comprises two first power switches 26 connected with each other in series. Each bridge arm of the three-phase voltage bridge arm unit 24 comprises two second power switches 27 connected with each other in series. The zero sequence bridge arm 29 comprises two third power switches 28 connected with each other in series. Three middle points of three bridge arms of the three-phase current bridge arm unit 23 are the three current output ends of the converter 22, namely, u.sub.3, v.sub.3 and w.sub.3 in FIG. 1(b), respectively. Three middle points of three bridge arms of the three-phase voltage bridge arm unit 24 are three voltage output ends of the converter 22, namely, u.sub.4, v.sub.4 and w.sub.4 in FIG. 1(b), respectively. A middle point of the zero sequence bridge arm 29 is represented as J.sub.3.

(12) The control windings and the converter side windings connect to the converter 22 by the star connection with a neutral point. Specifically, the beginning terminal a.sub.3 of the Phase-A control winding 3a, the beginning terminal b.sub.3 of the Phase-B control winding 3b, and the beginning terminal c.sub.3 of the Phase-C control winding 3c connect to the current output ends u.sub.3, v.sub.3 and w.sub.3 of the converter 22, respectively. The beginning terminal a.sub.4 of the Phase-A converter side winding 4a, the beginning terminal b.sub.4 of the Phase-B converter side winding 4b, and the beginning terminal c.sub.4 of the Phase-C converter side winding 4c connect to the voltage output ends u.sub.4, v.sub.4 and w.sub.4 of the converter 22, respectively. The end terminal x.sub.3 of the Phase-A control winding 3a, the end terminal y.sub.3 of the Phase-B control winding 3b, the end terminal z.sub.3 of the Phase-C control winding 3c, the end terminal x.sub.4 of the Phase-A converter side winding 4a, the end terminal y.sub.4 of the Phase-B converter side winding 4b and the end terminal z.sub.4 of the Phase-C converter side winding 4c connect to the middle point J.sub.3 of the zero sequence bridge arm 29 of the converter 22.

(13) The secondary windings supply load by a three-phase four-wire method. Specifically, the beginning terminal a.sub.2 of the Phase-A secondary winding 2a, the beginning terminal b.sub.2 of the Phase-B secondary winding 2b and the beginning terminal c.sub.2 of the Phase-C secondary winding 2c connected to three beginning terminals u.sub.2, v.sub.2, w.sub.2 of the load, respectively. The end terminal x.sub.2 of the Phase-A secondary winding 2a, the end terminal y.sub.2 of the Phase-B secondary winding 2b, and the end terminal z.sub.2 of the Phase-C secondary winding 2c connect to the middle point J.sub.2 of the load.

(14) As shown in FIG. 1(c), the filter 32 connects to the secondary windings in parallel by the star connection with neutral point. Specifically, each phase of the filter 32 comprises a filter capacitor 31 and a damping resistor 30 that connects to the filter capacitor 31 in series. Three beginning terminals of three phases of the filter 32 connect to u.sub.2, v.sub.2 and w.sub.2, respectively. Three end terminals of the three phases of the filter 32 connect to the middle point J.sub.2 of the load. The filter 32 can significantly reduce the higher harmonic content of the load voltage.

(15) Referring to FIG. 2 and FIG. 3, the iron core of the magnetic integrated hybrid distribution transformer comprises an iron beam unit, an iron yoke unit and a leakage magnetic core unit. In these two drawings, the iron beam unit comprises a Phase-A main transformer iron beam 10a, a Phase-B main transformer iron beam 10b, a Phase-C main transformer iron beam 10c, a Phase-A isolation transformer iron beam 11a, a Phase-B isolation transformer iron beam 11b and a Phase-C isolation transformer iron beam 11c. The iron yoke unit comprises a bottom iron yoke 17, a middle iron yoke 16, a Phase-C independent iron yoke 12, a C/A phase common iron yoke 13, an A/B phase common iron yoke 14 and a Phase-B independent iron yoke 15. The leakage magnetic core unit comprises a Phase-A main transformer leakage magnetic core 6a, a left Phase-B main transformer leakage magnetic core 6b1, a right Phase-B main transformer leakage magnetic core 6b2, a Phase-C main transformer leakage magnetic core 6c, a Phase-A isolation transformer leakage magnetic core 18a, a Phase-B isolation transformer leakage magnetic core 18b and a Phase-C isolation transformer leakage magnetic core 18c.

(16) The Phase-A main transformer iron beam 10a, the Phase-B main transformer iron beam 10b, and the Phase-C main transformer iron beam 10c are longitudinally arranged in parallel from left to right. The upper ends of the Phase-A main transformer iron beam 10a, the Phase-B main transformer iron beam 10b, and the Phase-C main transformer iron beam 10c connect to a bottom end of the middle iron yoke 16. Bottom ends of the Phase-A main transformer iron beam 10a, the Phase-B main transformer iron beam 10b and the Phase-C main transformer iron beam 10c connect to the bottom iron yoke 17. The Phase-C isolation transformer iron beam 11c, the Phase-A isolation transformer iron beam 11a and the Phase-B isolation transformer iron beam 11b are horizontally arranged and connected with each other from left to right. An end of the Phase-C isolation transformer iron beam 11c connects to an upper end of the Phase-C independent iron yoke 12. Both the Phase-C isolation transformer iron beam 11c and the Phase-A isolation transformer iron beam 11a connect to an upper end of the C/A phase common iron yoke 13. Both the Phase-A isolation transformer iron beam 11a and the Phase-B isolation transformer iron beam 11b connect to an upper end of the A/B phase common iron yoke 14. An end of the Phase-B isolation transformer iron beam 11b connects to an upper end of the Phase-B independent iron yoke 15. As a result, the phase shifting arrangement of the main transformer and the series isolation transformer winding is achieved. Bottom ends of the Phase-C independent iron yoke 12, the C/A phase common iron yoke 13, the A/B phase common iron yoke 14 and the Phase-B independent iron yoke 15 connect to an upper end of the middle iron yoke 16.

(17) The connection between the iron beams and the iron yokes is introduced as follows. A left end of the bottom iron yoke 17 connects to the bottom end of the Phase-A main transformer iron beam 10a, a middle portion of the bottom iron yoke 17 connects to a bottom end of the Phase-B main transformer iron beam 10b, a right end of the bottom iron yoke 17 connects to a bottom end of the Phase-C main transformer iron beam 10c. A left bottom portion of the middle iron yoke 16 connects to an upper end of the Phase-A main transformer iron beam 10a, while a left upper portion of the middle iron yoke 16 connects to a bottom end of the Phase-C independent iron yoke 12. The upper end of the Phase-C independent iron yoke 12 connects to a left end of the Phase-C isolation transformer iron beam 11c. A right bottom portion of the middle iron yoke 16 connects to an upper end of the Phase-C main transformer iron beam 10c, while a right upper portion of the middle iron yoke 16 connects to a bottom end of the Phase-B independent iron yoke 15. The upper end of the Phase-B independent iron yoke 15 connects to a right end of the Phase-B isolation transformer iron beam 11b. A middle bottom portion of the middle iron yoke 16 connects to an upper end of the Phase-B main transformer iron beam 10b, ⅓ of the upper portion of the middle iron yoke 16 connects to the bottom end of the C/A phase common iron yoke 13, and ⅔ of the upper portion of the middle iron yoke 16 connects to the bottom end of the A/B phase common iron yoke 14. A right end of the Phase-C isolation transformer iron beam 11c connects to the left end of the Phase-A isolation transformer iron beam 11a. Both the Phase-C isolation transformer iron beam 11c and the Phase-A isolation transformer iron beam 11a connect with the upper end of the C/A phase common iron yoke 13. The left end of the Phase-B isolation transformer iron beam 11b connects to the right end of the Phase-A isolation transformer iron beam 11a. Both the Phase-B isolation transformer iron beam 11b and the Phase-A isolation transformer iron beam 11a connect to the upper end of the A/B phase common iron yoke 14.

(18) The Phase-A secondary winding 2a, the Phase-A primary winding 1a and the Phase-A control winding 3a are layer-windings and concentrically wound around the Phase-A main transformer iron beam 10a from inside to outside. The Phase-A main transformer leakage magnetic core 6a is arranged at a left window of the main transformer and inserted between the Phase-A primary winding 1a and the Phase-A control winding 3a. The Phase-B secondary winding 2b, the Phase-B primary winding 1b and the Phase-B control winding 3b are layer-windings and concentrically wound around the Phase-B main transformer iron beam 10b from inside to outside. The Phase-B main transformer leakage magnetic core contains two parts, namely, a left Phase-B main transformer leakage magnetic core 6b1 and a right Phase-B main transformer leakage magnetic core 6b2. Both of them are inserted between the Phase-B primary winding 1b and the Phase-B control winding 3b, wherein: the left Phase-B main transformer leakage magnetic core 6b1 is arranged at the left window of the main transformer. While the right Phase-B main transformer leakage magnetic core 6b2 is arranged at a right window of the main transformer. The left Phase-B main transformer leakage magnetic core 6b1 and the right Phase-B main transformer leakage magnetic core 6b2 are symmetrically distributed around the Phase-B main transformer iron beam 10b. The Phase-C secondary winding 2c, the Phase-C primary winding 1c and the Phase-C control winding 3c are layer-windings and concentrically wound around the Phase-C main transformer iron beam 10c from inside to outside. The Phase-C main transformer leakage magnetic core 6c is arranged at the right window of the main transformer and inserted between the Phase-C primary winding 1c and the Phase-C control winding 3c.

(19) The Phase-C converter side winding 4c and the Phase-C grid side winding 5c are pancake windings and concentrically wound around the Phase-C isolation transformer iron beam 11c from left to right. The Phase-C isolation transformer leakage magnetic core 18c is sandwiched between the Phase-C converter side winding 4c and the Phase-C grid side winding 5c. The Phase-A converter side winding 4a and the Phase-A grid side winding 5a are pancake windings and concentrically wound around the Phase-A isolation transformer iron beam 11a from left to right. The Phase-A isolation transformer leakage magnetic core 18a is sandwiched between the Phase-A converter side winding 4a and the Phase-A grid side winding 5a. The Phase-B converter side winding 4b and the Phase-B grid side winding 5b are pancake windings and concentrically wound around the Phase-B isolation transformer iron beam 11b from left to right. The Phase-B isolation transformer leakage magnetic core 18b is sandwiched between the Phase-B converter side winding 4b and the Phase-B grid side winding 5b.

(20) As shown in FIG. 2, each iron yoke is in 45-degree connection with a corresponding iron beam (formed by laminations). FIG. 4(b) shows that the sizes of the Phase-A main transformer iron beam, the Phase-B main transformer iron beam, the Phase-C main transformer iron beam, the bottom iron yoke and the middle iron yoke are larger than sizes of the Phase-A isolation transformer iron beam, the Phase-B isolation transformer iron beam, the Phase-C isolation transformer iron beam, the C/A phase common iron yoke, and the A/B phase common iron yoke, which is beneficial for making full use of ferromagnetic materials. As shown in FIG. 4(a), air gaps between main transformer leakage magnetic cores and the middle/bottom iron yokes or between the isolation transformer leakage magnetic cores and the middle iron yoke/isolation transformer iron beam are adjustable, which contributes to flexible adjustment of leakage inductance.

(21) Referring to FIG. 4(c), a horizontal cross section of the Phase-A control winding 3a and the Phase-C control winding 3c is a combination of semicircle and ellipse, the horizontal cross section is an ellipse in the window of the main transformer and is a semicircle at an outer side of the window. A horizontal cross section of the Phase-B control winding 3b is completely elliptical. The elliptical and semi-elliptical windings not only provide sufficient space for the leakage magnetic core unit, but also reduce the circumference of the wire when the coil is wound, thereby saving materials.

(22) By controlling each bridge arm of the converter 22, the load voltage and the grid current can be controlled. For example, by controlling the current of the three-phase current converter, the harmful components such as harmonic, asymmetric, and negative components in the load current are compensated in real time. Based on the principle of the three-winding transformer, the grid currents are controlled to be sinusoidal, symmetric and unity power factor. By controlling the voltage of the three-phase voltage converter, the fluctuation, distortion and asymmetric components in the grid voltage are compensated in real time, so that the load voltage can be kept as a symmetric and stable sine wave.