Water-cooling multi-turn stator coil structure of power grid direct connection type ultra-high voltage phase modifier

Abstract

The invention relates to the technical field of ultrahigh-voltage phase modifier stator coils, and discloses a water-cooling multi-turn stator coil structure of a power grid direct connection type ultrahigh-voltage phase modifier, which comprises a plurality of coil bars, water connections at the nose ends of the coil bars are turn-dividing structures, and electric connections at the nose ends of the coil bars are turn-combining structures; the lower-layer winding bar comprises a first-turn winding bar and a second-turn winding bar, the upper-layer winding bar comprises a third-turn winding bar and a fourth-turn winding bar, and the upper-layer winding bar and the lower-layer winding bar jointly form a phase belt stator coil; the water-cooling multi-turn stator coil structure comprises a plurality of phase belt stator coils; the device is used for a 35kV power grid direct connection type ultra-high voltage phase modifier. According to the invention, the nose end of the coil bar is subjected to the separation design of water and electricity connection turn closing and turn separating, and the coil bar can be used in a 35kV power grid direct connection type ultra-high voltage phase modifier.

Description

Technical Field

[0001] This invention relates to a water-cooled multi-turn stator coil structure for a grid-connected ultra-high voltage synchronous condenser, belonging to the technical field of ultra-high voltage synchronous condenser stator coils. Background Technology

[0002] As the energy structure rapidly transitions towards renewable energy, distributed synchronous condensers (DCCs), as key equipment ensuring the stable operation of renewable energy power plants, play a crucial role in maintaining power system voltage stability and enhancing grid security. Direct-connected DCCs are directly connected to the 35kV busbar of renewable energy power plants or substations. This method reduces intermediate links, lowers energy losses, and improves system operating efficiency. Simultaneously, the direct-connection mode allows DCCs to respond more quickly and accurately to dynamic changes in the grid, effectively enhancing reactive power compensation and voltage support capabilities for renewable energy power plants. Direct-connected DCCs, with their dual technological and economic advantages, will become a significant choice for DCCs in future renewable energy power plants.

[0003] The stator coil is a key component for energy conversion and outputting electrical energy. When the voltage level rises to 35kV, a higher electric field strength and a more uneven electric field distribution will be generated. The structure of the stator coil needs to withstand higher voltages, but the current structure of the strip stator coil is already close to the limit of the synchronous condenser design and cannot be used for higher voltage conditions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a water-cooled multi-turn stator coil structure, wherein the strands of the coil bar adopt a combination of insulated copper flat wire and stainless steel air conductor, and the coil bar nose end has a separate form of water and electricity connection between the turns, which can be used in 35kV grid direct-connected ultra-high voltage synchronous condensers.

[0005] To address the aforementioned problems, the present invention provides a water-cooled multi-turn stator coil structure for a direct-connected ultra-high voltage synchronous condenser, comprising multiple coil bars. The water connection at the nose of the coil bars is a split-turn structure, and the electrical connection is a combined-turn structure. The lower coil bars include a first-turn coil bar and a second-turn coil bar, and the upper coil bars include a third-turn coil bar and a fourth-turn coil bar. The upper and lower coil bars together form a phase-band stator coil. The water-cooled multi-turn stator coil structure comprises multiple phase-band stator coils and is used in a 35kV direct-connected ultra-high voltage synchronous condenser.

[0006] The electrical connection in this technical solution is used to conduct 35kV current, while the water connection is used to transport cooling water. The two functions are independent to avoid mutual interference.

[0007] According to the present invention, the bar further comprises multiple insulated copper flat wires and at least one stainless steel hollow conductor, and the bar is transposed 360° along the axial direction in the groove.

[0008] According to the present invention, the stator coil has 48 slots, each slot has four turns of wire, and the number of poles is four.

[0009] According to the present invention, the ordinary ends of the electrical connection terminals of the upper and lower layer bars are connected by a frame-type copper sleeve structure with straight copper busbars, and the phase bars at the output terminals are connected to the connecting wires by a frame-type copper sleeve structure with bent copper busbars.

[0010] According to the present invention, the water connection terminal of the stator coil is further connected to a water box via a base plate.

[0011] According to the present invention, the cone angle of the stator coil structure is further 20°-30°.

[0012] According to the present invention, the cone angle of the stator coil structure is further 22°.

[0013] According to the present invention, all the said bars adopt a variable transition zone and variable span angle design, the starting circles of the upper and lower involutes are aligned, the involute segments of the bars are designed with variable gaps, the phase gap between each phase is greater than the same phase gap, and each bar in the upper and lower layers is an independent specification; the insulation thickness of the bar at the nose bifurcation point is a variable cross-section form.

[0014] According to the present invention, it further includes at least one support plate, one end of which is connected to a frame-type copper sleeve with straight copper busbar or a frame-type copper sleeve with bent copper busbar, and the other end is connected to a stainless steel base plate to enhance the rigidity of the nose support.

[0015] According to the present invention, the two support plates are symmetrically arranged on both sides of the corresponding copper sleeve.

[0016] The beneficial effects of this invention are as follows: 1. The electrical connection of the present invention connects the circuits in series to form ultra-high voltage; the water connection separates the turns, which can realize water cooling. Combined with the insulation cross-section change and gap treatment, the insulation hazards of ultra-high voltage are solved.

[0017] 2. The conductor of this invention uses a combination of copper flat wire and stainless steel hollow conductor, and the water connector is connected in turns to improve heat dissipation efficiency, thereby improving heat dissipation efficiency under ultra-high pressure. Attached Figure Description

[0018] Figure 1 A three-dimensional schematic diagram of a water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser according to the present invention; Figure 2 This is a schematic diagram of the lower layer wire rod structure of the present invention; Figure 3 This is a schematic diagram of the upper layer wire rod structure of the present invention; Figure 4 This is a schematic diagram of the connection between the upper and lower layer bars of a phase band stator according to the present invention; Figure 5 This is a schematic diagram of the variable cross-section at the bifurcation point of the upper and lower coils of the stator at the nose end of the present invention; Figure 6a This is a schematic diagram of the frame-type copper sleeve structure with straight copper busbar of the present invention; Figure 6b This is a schematic diagram of the frame-type copper sleeve structure with variable cross-section bent copper busbar of the present invention; Figure 7a This is a schematic diagram of the nasal tip water connection structure of the present invention; Figure 7b This is a schematic diagram of the support plate of the present invention.

[0019] Reference numerals in the attached drawings: 1. First turn bar; 2. Second turn bar; 3. Third turn bar; 4. Fourth turn bar; 5. Frame-type copper sleeve with straight copper busbar; 6. Frame-type copper sleeve with variable cross-section bent copper busbar; 7. Base plate; 8. Water box; 9. Support plate. Detailed Implementation

[0020] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings: As shown in the figure, this application embodiment provides a water-cooled multi-turn stator coil structure for a grid-connected ultra-high voltage synchronous condenser. The strands of the coil bars are composed of insulated copper flat wire and stainless steel hollow conductor braid. The water connection at the end of the bar is a split-turn structure, and the electrical connection is a combined-turn structure. The coils of each phase together form a complete conductive circuit, which can be used in 35kV grid-connected ultra-high voltage synchronous condensers. The insulated copper flat wire ensures conductivity, while the stainless steel hollow conductor serves as a cooling water flow channel, achieving a synergistic effect of conductivity and heat dissipation. The split-turn and combined-turn structures separate the current from the cooling water, reducing mutual interference and eliminating safety hazards.

[0021] Specifically, the stator coil has 48 slots, with four turns of wire in each slot, and four poles. The entire stator coil structure includes twelve phase stator coils. Each phase stator coil consists of upper and lower layer wires. The upper layer wires include the third turn wire (3) and the fourth turn wire (4), and the lower layer wires include the first turn wire (1) and the second turn wire (2). That is, each turn wire consists of two rows of wires, and each row of wires consists of eight insulated copper flat wires and two stainless steel hollow wires, which are transposed 360° along the axial direction within the slot. The stainless steel hollow wires are of smaller cross-section. After the four turns of wire are embedded in the corresponding slots, the electrical connection at the nose end is a combined turn structure, and the water connection is an independent split turn structure, forming a complete conductive heat dissipation unit. The 360° transposition within the stator slots offsets eddy current losses.

[0022] The stator coil end electrical connections are connected in a combined-turn structure, with the upper and lower coil bars connected together. Ordinary coil ends are connected using a frame-type copper sleeve structure 5 with straight copper busbars, while the output phase coils and connecting leads are connected using a frame-type copper sleeve structure 6 with bent copper busbars. The stator coil end water connections are a split-turn structure, allowing independent water output for each turn. The water connection end is connected to a water box 8 via a base plate 7.

[0023] The water connection structure and electrical connection structure at the stator coil end are connected as a whole by support plate 9, which can enhance the rigidity of the nose end support. Two stainless steel support plates 9 are set on both sides of the copper sleeve. One end of the support plate 9 is welded to the copper sleeve, and the other end is welded to the stainless steel base plate 7.

[0024] To accommodate the influence of factors such as the phase spacing of ultra-high voltage conductor bars, the nose gap of conductor bars, the space behind conductor bars, the axial length of the ends, and the cone angle, as well as the operability of the manufacturing process at the bends of the involute curves, the cone angle of the stator coil structure is 20°-30°, preferably 22°. All conductor bars adopt a variable transition zone and variable span angle design, with the starting circles of the upper and lower involute curves aligned. The involute curve segments of the conductor bars have a variable gap design, and the phase spacing between each phase band is greater than the same-phase spacing. The span angle of the upper and lower conductor bars within each phase band is adapted to the slot allocation of that phase band, and each conductor bar in the upper and lower layers is an independent specification.

[0025] The variable cross-sectional design of the insulation thickness of the bar at the nose-end bifurcation provides a compact and solid foundation for the end phase, making it suitable for altitudes up to 2000m. Preferably, the insulation thickness is 9.8mm before the bar nose-end bifurcation and gradually decreases to 3.9mm after the bifurcation.

[0026] The assembly process of this invention is as follows: Lower layer rods consisting of the first and second coiled rods 1 and 2, upper layer rods consisting of the third and fourth coiled rods 3 and 4 are sequentially embedded into grooves. The grooves are filled with insulating filler and compacted to ensure the rods are fixed. The third and fourth coiled rods 3 and 4 on the upper layer at the outlet end are aligned with the first and second coiled rods 1 and 2 on the lower layer, respectively. The third and fourth coiled rods 3 and 4 on the upper layer at the non-outlet end are aligned with the first and second coiled rods 2 and 1 on the lower layer, respectively, and are fixedly connected with corresponding copper sleeves for sealing and reducing contact resistance. The stainless steel hollow conduits of each coiled rod are welded to the water box 8 at both ends via the base plate 7, forming independent cooling channels. The water connectors are arranged with variable gaps, with a phase spacing ≥90mm and a same-phase spacing ≤20mm. Two support plates 9 are symmetrically welded to both sides of the corresponding copper sleeves, and the other end is welded to the base plate to improve the rigidity of the nose end. Electrical performance is tested after installation.

[0027] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A water-cooled multi-turn stator coil structure for a direct-connection ultra-high voltage synchronous condenser, characterized in that, It includes multiple coils, with the water connection at the coil nose being a split-turn structure and the electrical connection being a combined-turn structure; the lower coil includes a first-turn coil and a second-turn coil, and the upper coil includes a third-turn coil and a fourth-turn coil, the upper and lower coils together forming a phase-band stator coil; the water-cooled multi-turn stator coil structure includes multiple phase-band stator coils; it is used in 35kV grid direct-connected ultra-high voltage synchronous condensers.

2. The water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser as described in claim 1, characterized in that, The bar comprises multiple insulated copper flat wires and at least one stainless steel hollow conductor, and the bar is transposed 360° along the axial direction in the stator slot.

3. The water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser as described in claim 1, characterized in that, The stator coil has 48 slots, each slot contains four turns of wire, and has four poles.

4. The water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser as described in claim 1, characterized in that, The ordinary ends of the electrical connection terminals of the upper coil and the lower coil are connected by a frame-type copper sleeve structure with a straight copper busbar, and the phase wire bar at the output end is connected to the connecting wire lead using a frame-type copper sleeve structure with a bent copper busbar.

5. The water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser as described in claim 1, characterized in that, The water connection terminal of the stator coil is connected to a water box via the base plate.

6. The water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser as described in claim 1, characterized in that, The cone angle of the stator coil structure is 20°-30°.

7. The water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser as described in claim 6, characterized in that, The cone angle of the stator coil structure is 22°.

8. The water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser as described in claim 1, characterized in that, All the aforementioned bars adopt a variable transition zone and variable span angle design, with the starting circles of the upper and lower involutes aligned. The involute segments of the bars have a variable gap design, with the phase gap between each phase being greater than the same phase gap. Each bar in the upper and lower layers is an independent specification. The insulation thickness of the bars at the nose bifurcation point is a variable cross-section form.

9. The water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser as described in claim 4, characterized in that, It also includes at least one support plate, one end of which is connected to a copper sleeve with a straight copper busbar or a copper sleeve with a bent copper busbar, and the other end is connected to a stainless steel base plate to enhance the rigidity of the nose support.

10. The water-cooled multi-turn stator coil structure of a grid-connected ultra-high voltage synchronous condenser as described in claim 6, characterized in that, The two support plates are symmetrically arranged on both sides of the corresponding copper sleeve.

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