Phase-shifting transformer having symmetrical phase angles, and phase angle adjustment apparatus

Abstract

A phase-shifting transformer having symmetrical phase angles, and a phase angle adjustment apparatus comprising same. The phase-shifting transformer having symmetrical phase angles uses a single-core structure and includes three phases, wherein a first main winding of a current phase and a first auxiliary winding of a first adjacent phase are connected by means of a tap changer apparatus, and a second main winding of the current phase and a second auxiliary winding of a second adjacent phase are connected by means of a tap changer apparatus; two polarities at the first auxiliary winding and two polarities at the second auxiliary winding are connected in opposite polarity; the other ends of the first main winding and the second main winding are both connected to a power supply terminal or a load terminal of an external line; the auxiliary windings further lead out at least one neutral point output by means of connecting to the tap changer apparatuses; and the tap changer apparatuses allow switching between different tap positions. The present invention uses a single-core structure to realize symmetrical phase adjustment, thereby lowering costs and reducing the footprint; and a tap changer is located at the center point of a star-connected phase-adjusting winding, thereby preventing the tap changer from withstanding high-voltage impulses at a line terminal and lowering the insulation requirements for the tap changer.

Description

A phase-shifting transformer with symmetrical phase angle and a phase angle adjustment device

[0001] This application claims priority to Chinese Patent Application No. 202410939843.1, filed on July 15, 2024, entitled "A Phase Angle Symmetrical Phase Shifting Transformer and Phase Angle Adjustment Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention belongs to the field of phase-shifting transformer technology, specifically relating to a phase-shifting transformer with symmetrical phase angle and a phase angle adjustment device. Background Technology

[0003] A phase-shifting transformer is a special type of transformer capable of changing the phase and amplitude of voltage. When connected in series in a power line, it can effectively improve the voltage distribution of the power grid, reduce line losses, and is of great significance for optimizing power transmission, improving power grid structure, and enhancing power quality.

[0004] Currently, phase-shifting transformers on the market can be divided into single-core and double-core types based on differences in their core structure. Existing single-core phase-shifting transformers have a relatively small phase-shifting range, require the on-load tap changer to be located at the line end, and operate in harsh environments, making them unsuitable for high-voltage transmission lines. While double-core phase-shifting transformers allow the on-load tap changer to be located at the neutral point, they require a larger footprint and have higher manufacturing costs.

[0005] Summary of the Invention

[0006] In view of this, the present invention aims to provide a novel topology phase-shifting transformer suitable for high voltage levels, neutral point phase adjustment, and single-core structure, in order to solve the above-mentioned problems existing in existing single-core or dual-core phase-shifting transformers.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a phase-shifting transformer with symmetrical phase angles, employing a single-core structure comprising three phases, each phase including:

[0009] The main winding includes a first main winding and a second main winding;

[0010] The auxiliary winding includes a first auxiliary winding and a second auxiliary winding;

[0011] The tap changer is equipped with a polarity selection function at each auxiliary winding, which is used to connect the main winding with the auxiliary winding of the adjacent phase and can change the polarity of the connection.

[0012] One end of the first main winding of the current phase and the first auxiliary winding of the first adjacent phase, and one end of the second main winding of the current phase and the second auxiliary winding of the second adjacent phase, are respectively connected by a tap changer at the corresponding auxiliary winding with the same polarity.

[0013] The tap changer is connected with opposite polarities between the two polarities at the first auxiliary winding of the first adjacent phase and the two polarities at the second auxiliary winding of the second adjacent phase.

[0014] The other ends of the first and second main windings of the current phase are directly or indirectly connected to the power supply or load end of the external line to form a circuit loop.

[0015] The auxiliary winding also leads out at least one neutral point output through connection with the tap changer, which is used for the establishment or connection of the neutral point in the system.

[0016] The tap changer allows switching between different taps to adjust the voltage ratio of the auxiliary winding, thereby achieving simultaneous voltage and phase adjustment.

[0017] Furthermore, the tap changer achieves polarity selection by configuring a polarity selector.

[0018] Furthermore, the tap changer is also connected to a control module, which is used to dynamically adjust the connection state between the auxiliary winding and the main winding according to a preset algorithm. The tap changer is configured to adjust the connection state between the auxiliary winding and the main winding according to the instructions of the control module, so as to dynamically adjust the phase angle.

[0019] Furthermore, the control module determines the phase shift angle according to the following formula: β=30°-α

[0020] In the formula, α is the phase angle difference between the auxiliary winding voltage and the input voltage, β is the angle between the input voltage vector and the vertical reference line, and k is the ratio of the amplitude of the main winding voltage to the amplitude of the auxiliary winding voltage.

[0021] Furthermore, the tap changer is also used to make the phase angle of the phase-shifting transformer symmetrical in the positive and negative tap modes.

[0022] Furthermore, the connection status includes the connection method and / or the turns ratio.

[0023] Furthermore, all windings and tap changer devices of a phase-shifting transformer with symmetrical phase angles are connected inside the same enclosure before being led out or led out and then connected.

[0024] In a second aspect, the present invention provides a phase angle adjustment device, comprising:

[0025] The control unit is configured to control the tap changer to adjust the phase-shifting transformer winding connection state according to the target phase angle, so as to dynamically adjust the phase angle;

[0026] In addition, a phase-shifting transformer connected to the control unit, wherein the phase-shifting transformer is a phase-angle symmetrical transformer as described in the first aspect.

[0027] Furthermore, the control unit determines the phase shift angle according to the following formula: β=30°-α

[0028] In the formula, α is the phase angle difference between the auxiliary winding voltage and the input voltage, β is the angle between the input voltage vector and the vertical reference line, and k is the ratio of the amplitude of the main winding voltage to the amplitude of the auxiliary winding voltage.

[0029] Furthermore, the tap changer is also used to make the phase angle of the phase-shifting transformer symmetrical in the positive and negative tap modes.

[0030] In summary, this invention provides a phase-shifting transformer with symmetrical phase angles and a phase angle adjustment device. It adopts a single-core structure and includes three phases, each phase comprising: a main winding, including a first main winding and a second main winding; an auxiliary winding, including a first auxiliary winding and a second auxiliary winding; and a tap changer device. The tap changer device is equipped with a polarity selection function at each auxiliary winding, used to connect the main winding to the auxiliary winding of the adjacent phase, and capable of changing the polarity of the connection. One end of the first main winding of the current phase and the first auxiliary winding of the first adjacent phase, and one end of the second main winding of the current phase and the second auxiliary winding of the second adjacent phase, are respectively connected by the tap changer device. The auxiliary windings are connected with the same polarity at their respective auxiliary windings; the two polarities of the tap changer at the first auxiliary winding of the first adjacent phase and the two polarities at the second auxiliary winding of the second adjacent phase are connected with opposite polarities; the other ends of the first and second main windings of the first phase are directly or indirectly connected to the power supply or load end of the external line to form a circuit loop; the auxiliary windings also lead out at least one neutral point output through connection with the tap changer for establishing or connecting the neutral point of the system; the tap changer allows switching between different tap positions to adjust the voltage ratio of the auxiliary windings, thereby achieving simultaneous adjustment of voltage and phase. This invention uses a single-core structure, which reduces the floor space compared to a two-core transformer; compared to existing single-core transformers, the phase-shifting transformer of this invention uses the above structure to position the tap changer at the center point of the star-connected phase-shifting winding, avoiding the tap changer being subjected to high-voltage surges at the line ends and reducing the insulation requirements of the tap changer. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 is a topology diagram of a phase-shifting transformer with symmetrical phase angle provided in an embodiment of the present invention;

[0033] Figure 2 shows the topology and voltage phase diagram of a single-core asymmetric phase-shifting transformer provided in an embodiment of the present invention.

[0034] Figure 3 is a topology and voltage phase diagram of a single-core phase-shifting transformer provided in an embodiment of the present invention;

[0035] Figure 4 shows the topology and voltage phase diagram of the triangular-hexagonal phase-shifting transformer provided in an embodiment of the present invention.

[0036] Figure 5 shows the topology of the bi-core asymmetrical and symmetrical phase-shifting transformers provided in the embodiments of the present invention;

[0037] Figure 6 is a schematic diagram of the phase-shifting transformer winding connection with symmetrical phase angle provided in an embodiment of the present invention;

[0038] Figure 7a shows the voltage vector of a phase-shifting transformer with symmetrical phase angle under positive tap under no-load conditions provided in an embodiment of the present invention.

[0039] Figure 7b shows the voltage vector of a phase-shifting transformer with symmetrical phase angle under negative tap under no-load conditions provided in an embodiment of the present invention.

[0040] Figure 8 is a diagram showing the relative relationship of phase angles provided in an embodiment of the present invention. Detailed Implementation

[0041] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0042] As energy supply centers separate from power load centers, power systems are gradually evolving towards higher voltage, larger capacity, larger scale, interconnection, and long-distance transmission. This trend has promoted the interconnection of regional power grids and effectively improved the reliability of power supply. However, the continuous increase in grid capacity and the increasing complexity of system structure have also brought a series of challenges and problems.

[0043] In the interconnection of regional power grids, system power flow depends on the load of each node. Without any control measures, the power flow of parallel lines and ring networks is distributed according to impedance. This natural power distribution can lead to an unreasonable power flow distribution on lines, causing some lines to be overloaded while others have relatively low utilization. This unbalanced load distribution not only affects the overall efficiency of the power system but may also threaten the safe and stable operation of the grid. Therefore, appropriate power flow control measures are needed to regulate the transmitted power on the lines.

[0044] A phase-shifting transformer is a special type of transformer capable of changing the phase and amplitude of voltage. When connected in series in a power line, it can effectively improve the voltage distribution of the power grid, reduce line losses, and is of great significance for optimizing power transmission, improving power grid structure, and enhancing power quality.

[0045] Currently, phase-shifting transformers on the market can be classified into single-core and double-core types based on differences in core structure, and into asymmetrical and symmetrical types based on changes in voltage amplitude after phase shift.

[0046] If the excitation unit and series unit of a phase-shifting transformer share a single core, it is a single-core type; if the excitation unit and series unit each use independent cores, it is a double-core type. A transformer that does not change the line voltage amplitude after phase shifting is a symmetrical type, and vice versa.

[0047] Advantages and disadvantages of single-core type: It has a simple structure, but the voltage regulating winding and the on-load tap changer are directly connected to the line end, directly withstanding short-circuit current and overvoltage. If necessary, series reactors and surge arresters are required. It is mostly used for voltage levels of 110kV and below.

[0048] Advantages and disadvantages of the dual-core design: The tap changer is located on the neutral point side, effectively reducing the insulation level. The dual-core PST structure still has sufficient impedance to meet the product's short-circuit withstand capability requirements at zero phase shift angle, eliminating the need for a series reactor. The disadvantage of this structure is its complexity, but it offers flexible combinations and a high degree of design freedom.

[0049] Please refer to Figure 1, which is a topology diagram of a phase-angle symmetrical phase-shifting transformer with phase 1 as an example in some embodiments.

[0050] The following is a brief introduction to the connection topology of a typical phase-shifting transformer.

[0051] Please refer to Figure 2, which is a diagram of the topology and voltage phase of a single-core asymmetric phase-shifting transformer.

[0052] Taking phase A as an example: the secondary voltage regulating winding coupled to VBC is connected in series in the phase A line, because V BC and V SA The phases of the voltages are perpendicular to each other, therefore the compensation voltage ΔV A With V SAThey are orthogonal. Adjusting the tap changer and polarity switch on the voltage regulating winding can change the compensation voltage ΔV. A The size and direction are adjusted to control the phase shift angle α.

[0053] Asymmetrical phase-shifting transformers change the voltage amplitude after phase shifting. The larger the phase shift angle, the greater the change in voltage amplitude, which may lead to the line voltage exceeding the limit after phase shifting. Therefore, the phase shifting range of asymmetrical phase-shifting transformers is relatively small.

[0054] Please refer to Figure 3, which is a diagram of the topology and voltage phase of a single-core symmetrical phase-shifting transformer.

[0055] The single-core symmetrical voltage regulating winding is divided into two parts: the source-side winding and the load-side winding. Both windings are equipped with on-load tap changers, and their positions must be kept consistent to ensure that the compensation voltage on both windings is equal.

[0056] Please refer to Figure 4, which is a diagram of the topology and voltage phase of a delta-hexagonal phase-shifting transformer.

[0057] Similar to the single-core symmetrical design, the voltage regulating winding is divided into two equal parts: the source-side winding and the load-side winding. Both windings are equipped with on-load tap changers with consistent tap positions, and the compensation voltages on both windings are the same. The main difference is that the inner delta winding is connected to the voltage regulating coil and then connected in series to form a hexagonal connection.

[0058] Please refer to Figure 5, which shows the topology of a two-core asymmetric and symmetric phase-shifting transformers.

[0059] In a single-core phase-shifting transformer, the voltage regulating winding and the on-load tap changer are directly connected in series in the line. The on-load tap changer is directly affected by the system overvoltage and short-circuit current, which is detrimental to the safe and stable operation of the on-load tap changer. Therefore, it is not suitable for high voltage levels. When the voltage level is 220kV and above, a series transformer is required to isolate the voltage regulating winding from the line, i.e., a double-core type.

[0060] The excitation unit and series unit of the two-core phase-shifting transformer use separate transformers. The on-load tap changer is isolated from the system through the series transformer and is no longer directly affected by system overvoltage and short-circuit current, making it suitable for high voltage levels. Table 1 compares phase-shifting transformers with different topologies.

[0061] Table 1 Comparison of Phase-Shifting Transformers with Different Topologies

[0062] In summary, existing single-core phase-shifting transformers suffer from a small phase-shifting range, require on-load tap changers to be located at the line end, and operate in harsh environments, making them unsuitable for high-voltage transmission lines. While double-core phase-shifting transformers allow on-load tap changers to be located at the neutral point, they require a large footprint and have high manufacturing costs. Therefore, this invention proposes a phase-shifting transformer and its phase angle adjustment device suitable for high voltage levels (220kV and above), neutral point phase adjustment, and a single-core structure with symmetrical phase angles.

[0063] The following is a detailed description of an embodiment of a phase-shifting transformer with phase angle symmetry according to the present invention.

[0064] This embodiment provides a phase-shifting transformer with symmetrical phase angles, employing a single-core structure and comprising three phases. Each phase includes: a main winding, comprising a first main winding and a second main winding; an auxiliary winding, comprising a first auxiliary winding and a second auxiliary winding; and a tap changer, wherein the tap changer is equipped with a polarity selection function at each auxiliary winding for connecting the main winding with the auxiliary winding of the adjacent phase, and is capable of changing the polarity of the connection. Between one end of the first main winding of the current phase and the first auxiliary winding of the first adjacent phase, and between one end of the second main winding of the current phase and the second auxiliary winding of the second adjacent phase, the tap changer is used to select the polarity of the corresponding auxiliary winding. The windings are connected with the same polarity; the tap changer is connected with opposite polarities between the two polarities at the first auxiliary winding of the first adjacent phase and the two polarities at the second auxiliary winding of the second adjacent phase; the other ends of the first and second main windings of the current phase are directly or indirectly connected to the power supply or load end of the external line to form a circuit loop; the auxiliary windings also lead out at least one neutral point output through connection with the tap changer for the establishment or connection of the neutral point of the system; the tap changer allows switching between different positions to adjust the voltage ratio of the auxiliary windings, thereby achieving simultaneous adjustment of voltage and phase.

[0065] It should be noted that the phase-shifting transformer with symmetrical phase angle in this embodiment has a three-phase structure, which can handle three-phase AC power systems and is suitable for multi-phase application environments such as power transmission and motor control. Each phase includes four main parts: at least two main windings, a first auxiliary winding, a second auxiliary winding, and a tap changer device for adjusting voltage and phase.

[0066] The first main winding of the current phase (e.g., phase 1) is connected to the first auxiliary winding of the adjacent phase (phase 2 or phase 3) via the polarity selection function of the tap changer. This polarity selection function adjusts the voltage and phase by changing the polarity connected to the auxiliary winding of phase 2 (or phase 3). Specifically, one polarity is connected to the first auxiliary winding of phase 2 (or phase 3) via the polarity selection function, and the other polarity is connected to the second auxiliary winding of phase 3 (or phase 2).

[0067] The second main winding of the current phase (e.g., phase 1) is connected to the second auxiliary winding of another adjacent phase (phase 3 or phase 2) via the polarity selection function of the tap changer. This connection pattern is cross-connected with the auxiliary winding of the first main winding; that is, if the first main winding is connected to the auxiliary winding of phase 2, then the second main winding is connected to the auxiliary winding of phase 3, and vice versa. This cross-connection configuration increases the flexibility of voltage and phase adjustment. The first main winding of the current phase is connected to the first auxiliary winding of the first adjacent phase, and the second main winding is connected to the second auxiliary winding of the second adjacent phase with the same polarity via the tap changer, achieving precise phase control. The auxiliary windings of the first and second adjacent phases are connected with opposite polarities to further adjust the phase difference.

[0068] The other ends of the first and second main windings are respectively connected to the incoming or outgoing terminals of the power system, forming a closed loop to ensure the transmission of electrical energy.

[0069] The center point of the auxiliary winding (the neutral point of the star connection) is led out through its respective tap selector and can be used as the neutral point connection of the system or for grounding, which is crucial for system stability and control of the neutral point voltage.

[0070] This embodiment allows for flexible control of the voltage phase of phase 1 relative to the phase of phase 2 or phase 3 by adjusting the polarity selector and tap changer, thereby achieving fine-tuning of the phase relationship of the entire three-phase system. This is particularly important for complex power systems or motor drive applications requiring precise phase matching. Furthermore, this embodiment employs a single-core structure, with the main coil and the other two phase-adjusting coils achieving phase adjustment. The tap changer is located at the center point of the star-connected auxiliary winding, reducing the insulation requirements of the tap changer. The polarity switches of the two tap changers are connected to the corresponding terminals of the two auxiliary windings, ensuring consistent phase angles under extreme positive and negative taps, reducing the through-voltage of the main winding, and improving equipment reliability.

[0071] In a preferred embodiment of the present invention, the tap changer device achieves polarity selection function by configuring a polarity selector.

[0072] Please refer to Figure 1 again. Taking phase 1 as an example, its connection topology is as follows: The first main winding of phase 1 is connected to the tap changer polarity selector. One polarity of the tap changer polarity selector is connected to one auxiliary winding of phase 2 (or phase 3), and the other polarity is connected to one auxiliary winding of phase 3 (or phase 2). The second main winding of phase 1 is connected to another tap changer polarity selector. One polarity of the tap changer polarity selector is connected to one auxiliary winding of phase 3 (or phase 2), and the other polarity is connected to one auxiliary winding of phase 2 (or phase 3). The other output of the first main winding is connected to the incoming (or outgoing) terminal of the line, and the other output of the second main winding is connected to the outgoing (or incoming) terminal of the line. The tap changer output of the auxiliary winding is connected to the tap changer selector and then led out as the neutral point. The polarity selection function of the tap changer not only affects the phase but can also be used in conjunction with different taps (or tap positions) to change the neutral point potential, thereby indirectly regulating the output voltage of the transformer. In the phase-shifting transformer with symmetrical phase angles in this embodiment, this adjustment is very important for meeting the voltage requirements under different load conditions.

[0073] In a preferred embodiment of the present invention, the auxiliary winding and the tap changer are also connected to a control module. The control module is used to dynamically adjust the connection state between the auxiliary winding and the main winding according to a preset algorithm, so as to realize that the phase angle of the output voltage between the current phase and the adjacent phase is continuously adjustable. The tap changer is configured to adjust the connection state between the auxiliary winding and the main winding according to the instructions of the control module.

[0074] In a further embodiment of the present invention, the control module determines the size of the phase shift angle according to the following formula: β=30°-α

[0075] In the formula, α is the phase angle difference between the auxiliary coil voltage and the input voltage, β is the angle between the input voltage vector and the vertical reference line, and k is the ratio of the amplitude of the main coil voltage to the amplitude of the auxiliary coil voltage.

[0076] In a further embodiment of the present invention, when the tap changer is in a positive tap or a negative tap, the phase angle of the phase-shifting transformer is symmetrical under the positive and negative tap conditions.

[0077] The calculation of the phase angle in the above embodiments will be described below with reference to Figures 6-8.

[0078] Figure 6 shows a schematic diagram of the winding connection of the phase-shifting transformer with symmetrical phase angles in this technical solution, where A3-C4 are the two auxiliary windings of the three phases, and A1-C2 are the two main windings of the three phases. Figures 7a and 7b show the voltage vectors of the phase-shifting transformer with symmetrical phase angles under no-load conditions with positive and negative taps, respectively. Figure 8 shows the relative relationship of the phase angle adjustment of the phase-shifting transformer with symmetrical phase angles. As shown in Figure 7, according to the definition of three-phase electricity, the phase difference between phase voltages in the same voltage system of a normally operating transformer is 120°. In addition, according to the principle of magnetic induction, the coils on the same iron core column have the same phase angle. As shown in Figure 8, taking the vertical direction as the reference, we have U A1 The phase angle is 0°, let U SA The phase angle difference is β, U SA with U B3 Phase angle difference α.

[0079] Let U B3 =kU A1 Then we have:

[0080] Substituting into formula (1), we get:

[0081] According to geometric relations, we have: β=120°-90°-α=30°-α (7)

[0082] Furthermore, in one embodiment, in the topology shown in Figure 6, the connection positions of the first main winding and the second winding can be interchanged; the connection positions of the first auxiliary winding and the second auxiliary winding can also be interchanged. In this embodiment, the connection positions of the first main winding and the second main winding can be interchanged. This means that the design has a certain degree of flexibility, allowing the winding connection method to be adjusted according to specific needs or installation conditions without changing the overall operating principle. This design can simplify the production process, reduce the types of spare parts, and provide convenience during maintenance and fault replacement.

[0083] In one implementation, in the topology shown in Figure 6, the two tap changers can be adjusted synchronously or asynchronously to adjust the voltage amplitude simultaneously. The polarity selector of the tap changer can be eliminated; one end of the main winding is directly connected to one end of the phase-adjusting winding, achieving unidirectional phase angle adjustment. In this embodiment, the polarity selector of the tap changer is eliminated, and the main winding is directly connected to the phase-adjusting (auxiliary) winding. While this eliminates the bidirectional phase angle adjustment capability, it simplifies the structure, reduces costs, and still achieves unidirectional phase angle adjustment. This is a feasible solution for applications requiring only unidirectional phase shift, such as load regulation where phase requirements are not so stringent.

[0084] In one implementation, all windings and tap changers can be connected within the same enclosure and then brought out, or brought out and then connected. All windings and tap changers can be pre-connected and integrated within a single enclosure, or connected separately and then integrated. The former improves the overall compactness and ease of installation, reducing on-site assembly workload and the probability of errors. The latter facilitates customized needs or on-site adjustments, especially in situations requiring flexible configuration based on actual conditions. This design considers both manufacturing flexibility and convenience for on-site applications.

[0085] In one implementation, the tap changer also serves to ensure phase angle symmetry of the phase-shifting transformer in both positive and negative tap modes. Phase angle symmetry is crucial for stable operation in multiphase systems. By selecting appropriate connection methods and polarities between auxiliary windings of different phases, the tap changer can fine-tune the phase difference, ensuring symmetrical phase angles among the three phases across different voltage levels (including positive and negative taps). This means that the phase relationship between the three-phase currents or voltages remains consistent regardless of the tap changer's position, avoiding potential imbalances in the system and improving system compatibility and efficiency.

[0086] The above is a detailed description of an embodiment of a phase-angle symmetrical phase-shifting transformer of the present invention. The following is a detailed description of an embodiment of a phase angle adjustment device for a phase-angle symmetrical phase-shifting transformer of the present invention.

[0087] This embodiment provides a phase angle adjustment device for a phase-shifting transformer with symmetrical phase angles, including:

[0088] The control unit is configured to control the tap changer to adjust the connection state of the phase-shifting transformer windings according to the target phase angle, so as to dynamically adjust the phase angle of the output voltage.

[0089] In addition, a phase-shifting transformer connected to the control unit, wherein the phase-shifting transformer is a phase-angle symmetrical phase-shifting transformer as provided in the aforementioned embodiments.

[0090] In a further embodiment of the present invention, the control unit determines the magnitude of the phase shift angle according to the following formula: β=30°-α

[0091] In the formula, α is the phase angle difference between the auxiliary coil voltage and the input voltage, β is the angle between the input voltage vector and the vertical reference line, and k is the ratio of the amplitude of the main coil voltage to the amplitude of the auxiliary coil voltage.

[0092] In a further embodiment of the invention, the tap changer is also used to make the phase angle of the phase-shifting transformer symmetrical in the positive and negative tap modes.

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A phase angle symmetrical phase-shifting transformer, characterized in that The single-core structure contains three phases, each of which includes: a main winding including a first main winding and a second main winding; an auxiliary winding including a first auxiliary winding and a second auxiliary winding; a tapping switch device, which is equipped with a polarity selection function at each auxiliary winding, is used to connect the main winding with the auxiliary winding of the adjacent phase and can change the polarity of the connection; one end of the first main winding of the current phase and the first auxiliary winding of the first adjacent phase, and one end of the second main winding of the current phase and the second auxiliary winding of the second adjacent phase, are respectively connected in the same polarity through the tapping switch device at the corresponding auxiliary winding; the two polarities of the first auxiliary winding of the first adjacent phase and the two polarities of the second auxiliary winding of the second adjacent phase are connected in different polarities through the tapping switch device; the other end of the first main winding and the second main winding of the current phase are directly or indirectly connected to the power supply end or load end of the external circuit to form a circuit loop; the auxiliary winding also leads at least one neutral point output through the connection with the tapping switch device, which is used to establish or connect the neutral point of the system; the tapping switch device allows switching between different gears to adjust the voltage ratio of the auxiliary winding, thereby achieving simultaneous adjustment of voltage and phase.

2. The phase angle symmetrical phase shifting transformer of claim 1, wherein, The tapping switch device realizes the polarity selection function through the configuration of a polarity selector.

3. The phase angle symmetrical phase shifting transformer of claim 2, wherein, The tapping switch device is also connected to a control module, which is used to dynamically adjust the connection state between the auxiliary winding and the main winding according to a preset algorithm, and the tapping switch device is configured to adjust the connection state between the auxiliary winding and the main winding according to the instructions of the control module to dynamically adjust the phase angle.

4. The phase angle symmetrical phase shifting transformer of claim 3, wherein, The control module determines the size of the phase shift angle according to the following formula: β = 30° - a In the formula, α is the phase angle difference between the auxiliary winding voltage and the input voltage, β is the included angle between the input voltage vector and the vertical reference line, and k is the ratio of the amplitude of the main winding voltage to the auxiliary winding voltage.

5. The phase angle symmetrical phase shifting transformer of claim 3, wherein, The tapping switch device is also used to make the phase angle of the phase-shifting transformer symmetric in the positive and negative tapping modes.

6. The phase angle symmetrical phase shifting transformer of claim 3, wherein, The connection state includes the connection mode and / or the number of turns.

7. The phase angle symmetrical phase shifting transformer of claim 1, wherein, All windings of the phase angle symmetric phase-shifting transformer and the tapping switch device are connected inside the same box shell and then led out or led out and then connected.

8. A phase angle adjusting device, characterized by It includes: a control unit configured to control the tapping switch device to adjust the connection state of the phase-shifting transformer winding according to the target phase angle to dynamically adjust the phase angle; and a phase-shifting transformer connected to the control unit, which is a phase angle symmetric phase-shifting transformer as claimed in any one of claims 1-7.

9. The phase angle adjusting device according to claim 8, characterized in that The control unit determines the size of the phase shift angle according to the following formula: β = 30° - a In the formula, α is the phase angle difference between the auxiliary winding voltage and the input voltage, β is the included angle between the input voltage vector and the vertical reference line, and k is the ratio of the amplitude of the main winding voltage to the auxiliary winding voltage.

10. The phase angle adjustment device of claim 8, wherein, The tapping switch device is also used to make the phase angle of the phase-shifting transformer symmetric in the positive and negative tapping modes.

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