Winding wiring structure of step-down phase-shifting distribution transformer

Abstract

The invention discloses a winding wiring structure of a step-down phase-shifting distribution transformer, and particularly relates to the field of transformers, the winding wiring structure comprises a transformer winding wiring structure, the transformer is of a three-phase structure, an iron core column is arranged in the transformer, and the iron core column is sleeved with two phase modulation windings, an excitation winding, a voltage regulation winding and a low-voltage winding; one excitation winding and one voltage regulating winding are connected in series to form a high-voltage voltage regulating unit, the three-phase high-voltage voltage regulating units are connected end to end to form triangular connection, and the triangular connection comprises three vertexes. The phase-shifting transformer is of a single-body structure, the number of windings is small, wiring is simple, compared with a multi-transformer combined structure achieving the same function, cost is low, occupied space is small, additional devices such as newly-added lines and switches are not needed, compared with a phase-shifting step-down transformer of a double-body structure, the structure is greatly simplified, design and manufacturing difficulty is lowered, and the cost is reduced. And the operation reliability of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and more specifically, to a winding connection structure of a step-down phase-shifting distribution transformer. Background Art

[0002] The existing step-down transformers in the distribution network only have the function of voltage regulation and cannot control the power flow distribution of specific lines in the complex distribution network. Based on this, a combination of a conventional step-down transformer and a phase-shifting transformer is currently adopted, enabling the step-down transformer to change the phase of the voltages on both sides of the transmission line, thereby being able to control the power flow distribution of specific lines in the complex distribution network, and also having the step-down function of the original distribution transformer and providing a new function of closing the loop on the high-voltage side.

[0003] However, the combination of the conventional step-down transformer and the phase-shifting transformer adopted in the above-mentioned existing technology increases the number of transformers, resulting in a more complex wiring of the entire power system, increased land occupation, and also a very high cost due to the increased investment in related lines and switches, as well as a deterioration in the operation reliability and maintainability due to the complexity of the system. Summary of the Invention

[0004] The winding connection structure of a step-down phase-shifting distribution transformer provided by the present invention aims to solve the following problems: The existing method of combining a conventional step-down transformer and a phase-shifting transformer to control the power flow distribution of specific lines in the complex distribution network increases the number of transformers, resulting in a more complex wiring of the entire power system and increased land occupation.

[0005] To achieve the above object, the present invention provides the following technical solution: A winding connection structure of a step-down phase-shifting distribution transformer includes a transformer and a transformer winding connection structure. The transformer is of a three-phase structure, and an iron core column is arranged inside the transformer. Two phase-adjusting windings, an exciting winding, a voltage-regulating winding, and a low-voltage winding are sleeved on the iron core column;

[0006] An exciting winding and a voltage-regulating winding are connected in series to form a high-voltage voltage-regulating unit. The three-phase high-voltage voltage-regulating units are connected end to end to form a delta connection, and the delta connection includes three vertices;

[0007] The phase-adjusting winding includes a high-voltage side and a low-voltage side, and voltage-regulating switches are installed on both the high-voltage side and the low-voltage side. The three vertices are respectively connected to the three-phase phase-adjusting windings;

[0008] The low-voltage winding includes phase a, phase b, phase c, and phase zero. The low-voltage sides of the three-phase phase-adjusting windings are respectively connected to the connection terminals of the three-phase low-voltage windings.

[0009] In a preferred embodiment, the three-phase low-voltage windings are connected in a star connection.

[0010] In a preferred embodiment, the transformer is powered by high voltage on both sides, and the connection between the high voltage and the low voltage is Dy connection, where Dy represents Delta - Y connection.

[0011] In a preferred embodiment, the clock ordinal number labels between the high - voltage side and the low - voltage side of the transformer are the same as those commonly used in ordinary distribution transformers.

[0012] In a preferred embodiment, the connection between the two sides of the transformer is a corner - connected symmetric phase - shifting structure.

[0013] In a preferred embodiment, a phase - regulating switch is installed on the high - voltage side of the phase - regulating winding, and the phase - regulating switch is used to change the phase difference of the voltage between the two sides.

[0014] The beneficial effects of the present invention are as follows:

[0015] 1. For the winding connection structure of the step - down phase - shifting distribution transformer proposed by the present invention, the phase - shifting transformer has a single - body structure, with fewer windings and simple wiring. Compared with the combined structure of multiple transformers with the same function, it has a lower cost, occupies less space, has no additional devices such as new lines and switches, and is much simpler than the phase - shifting step - down transformer structure with a double - body structure, reducing the design and manufacturing difficulty and improving the reliability of the system operation.

[0016] 2. For the winding connection structure of the step - down phase - shifting distribution transformer proposed by the present invention, the phase - shifting function between the two sides of the power supply and the step - down function between the power supply side and the load side are realized by adding a phase - regulating winding and switch to the wiring structure of the step - down distribution transformer with a Dy connection for the high - voltage and low - voltage connection groups and adopting a special wiring method. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the winding connection of the present invention.

[0018] Figure 2 It is a schematic diagram of the voltage vectors of each wire end of the present invention.

[0019] Figure 3 It is a schematic diagram of the current vectors of each wire end of the present invention.

[0020] The reference numerals are: 1. Phase - regulating winding; 2. Excitation winding; 3. Voltage - regulating winding; 4. Low - voltage winding. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following further describes the present application in detail with reference to the drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non - essential improvements and adjustments to the present application based on the above application content.

[0022] Referring to the attached description Figures 1 to 3 , a winding connection structure of a step-down phase-shifting distribution transformer, including a transformer and a winding connection structure of the transformer. The transformer is a three-phase structure, and a core column is arranged inside the transformer. Two phase-adjusting windings 1, one exciting winding 2, one voltage-regulating winding 3, and one low-voltage winding 4 are sleeved on the core column; one exciting winding 2 and one voltage-regulating winding 3 are connected in series to form a high-voltage voltage-regulating unit. The three-phase high-voltage voltage-regulating units are connected end to end to form a delta connection, and the delta connection includes three vertices; the phase-adjusting winding 1 includes a high-voltage side and a low-voltage side, and voltage-regulating switches are installed on both the high-voltage side and the low-voltage side. The three vertices are respectively connected to the three-phase phase-adjusting windings 1; the low-voltage winding 4 includes phase a, phase b, phase c, and phase zero. The low-voltage sides of the three-phase phase-adjusting windings 1 are respectively connected to the connection terminals of the three-phase low-voltage windings 4.

[0023] The implementation scenario is specifically as follows: The transformer is a three-phase structure, and there are a total of 5 windings in each phase, namely two phase-adjusting windings 1, one exciting winding 2, one voltage-regulating winding 3, and one low-voltage winding 4. There are a total of fifteen windings in three phases. The exciting winding 2 in each phase and the voltage-regulating winding 3 in this phase are connected in series to form a group of high-voltage voltage-regulating units in this phase. This connection method can realize the regulation and stabilization of the high-voltage side voltage. The exciting winding 2 provides exciting current, and the voltage-regulating winding 3 controls the voltage magnitude of the high-voltage side by adjusting the turn ratio of the winding. Then, the three groups of high-voltage voltage-regulating units in three phases are connected end to end to form a triangle, and the triangle connection forms a triangular loop. This connection method can realize the balance and stabilization of the high-voltage side voltage. The connection of the triangular loop forms a low-impedance power path, enabling the high-voltage side voltage to be evenly distributed among each phase. The vertices of the triangular connection in each phase are respectively connected to two phase-adjusting windings 1 of different phases, and the two phase-adjusting windings 1 of different phases are respectively connected to the vertices of the triangular loop. This connection method can realize the phase adjustment of the high-voltage side voltage. The phase-adjusting winding 1 changes the phase difference of the high-voltage side voltage by adjusting the turn ratio and relative position of the winding to achieve phase adjustment and control. Two phase-adjusting switches are respectively installed on the two phase-adjusting windings 1 in each phase, and the phase-adjusting switches are used to change the phase difference of the voltage between the two sides. By adjusting the state of the phase-adjusting switches, the phase difference of the high-voltage side voltage can be adjusted and controlled, and three line terminals are led out and respectively connected to the three phases of two high-voltage sides: S1, S2, S3, and the three phases of another high-voltage side: L1, L2, L3. The three-phase low-voltage windings 4 are connected in a conventional star connection, and three line terminals are led out and respectively connected to phases a, b, and c, and a neutral point line terminal is led out and connected to phase zero. By connecting the neutral point line terminal to phase zero, a grounding point can be provided, the three-phase load can be balanced, and a path for zero-sequence current can be provided, thereby improving the safety, stability, and reliability of the power system.

[0024] Referring to the attached description Figures 1 to 3 , the three-phase low-voltage windings 4 are connected in a star connection.

[0025] It should be noted that in a star connection, the ends of the three low-voltage windings 4 are connected together through a neutral point, which can provide a shared neutral point that can be used to connect to the ground wire or guide the zero-sequence current, thereby achieving current balance and symmetry. The neutral point can be connected to the ground, and grounding can reduce the voltage to the ground, which is very important for reducing the amplitude of the voltage to the ground and reducing the impact of ground faults.

[0026] Refer to the attached drawings of the specification Figures 1 to 3 The transformer is powered by high voltage on both sides, and the connection method between the high voltage and the low voltage is Dy connection, where Dy represents Delta-Y connection.

[0027] It should be noted that Dy connection in a three-phase transformer can reduce harmonic voltage, reduce the flow of zero-sequence current, and improve the reliability of the system.

[0028] Refer to the attached drawings of the specification Figures 1 to 3 The clock ordinal number label between the high-voltage side and the low-voltage side of the transformer is the same as that commonly used in ordinary distribution transformers.

[0029] It should be noted that when the clock ordinal number label between the high voltage and the low voltage is the same as that of an ordinary distribution transformer, it is convenient for design, installation, and operation and maintenance. Transformers with the same label can be directly selected for replacement, or new transformers compatible with the existing system can be added without additional adjustment or re-labeling.

[0030] Refer to the attached drawings of the specification Figures 1 to 3 The two phase-adjusting windings 1 are respectively connected to two phase-adjusting switches.

[0031] It should be noted that by connecting the two phase-adjusting windings 1 to two phase-adjusting switches, independent adjustment of the phase difference of each phase can be achieved. This enables more flexible control of the voltage waveform and phase angle of each phase in a three-phase system. Independent phase adjustment is very useful for achieving precise power factor correction, improving power quality, and enhancing the stability of the power system. Connecting the phase-adjusting windings 1 to the phase-adjusting switches respectively can achieve isolation of phase adjustment. In this way, when the phase difference of a certain phase needs to be adjusted, it will not interfere with other phases. This design of interference isolation can effectively ensure the stability and reliability of the system.

[0032] Refer to the attached drawings of the specification Figures 1 to 3 The phase-adjusting winding 1 is connected to a voltage regulating switch, which is used to change the voltage transformation ratio and adjust the amplitude of the voltage without changing the phase angle difference between the high voltage and the low voltage.

[0033] It should be noted that by adjusting the voltage regulating switch, precise control of the voltage transformation ratio and amplitude can be achieved. This is very useful for meeting different load requirements, grid regulation, and power system stability. By adjusting the voltage amplitude, load changes can be accommodated and normal operation of equipment ensured; since the voltage regulating switch only changes the voltage amplitude without changing the phase angle difference, this connection method can keep the phase angle difference between the high and low voltages unchanged. In a power system, the phase angle difference is very important for maintaining grid stability and proper operation. By keeping the phase angle difference unchanged, grid instability or other problems can be avoided; in a power system, when changing the voltage transformation ratio and regulating the voltage, if the phase angle difference is changed simultaneously, it may have an adverse impact on other equipment and systems. By connecting the phase regulating winding 1 to the voltage regulating switch, the voltage amplitude can be independently controlled without affecting the phase angle difference, thereby reducing unnecessary interference to other equipment and systems.

[0034] Refer to the attached drawings of the specification Figures 1 to 3 , the connection between the two sides of the transformer is a corner-connected symmetric phase-shifting structure.

[0035] It should be noted that the transformer connection method of the corner-connected symmetric phase-shifting structure can achieve the advantages of a wide phase adjustment range, uniform current distribution, and power control and regulation, providing greater flexibility and stability for the operation and management of the power system.

[0036] Refer to the attached drawings of the specification Figures 1 to 3 , a phase regulating switch is installed on the high-voltage side of the phase regulating winding 1, the connection between the two high-voltage sides is a corner-connected symmetric phase-shifting structure, and the phase regulating switch is used to change the phase angle difference of the voltage between the two sides.

[0037] It should be noted that by using the phase regulating switch, the phase angle difference between the two high-voltage sides can be changed, that is, the phase angle of the voltage waveform can be adjusted. This is very important for the operation and control of the power system. The adjustment of the phase angle difference can achieve power factor correction, improvement of power quality, and enhancement of grid stability in the power system; by adjusting the phase angle difference, the flow direction and magnitude of power in the power system can be controlled. In a complex power system, it is necessary to adjust the power flow according to the load demand and system operating conditions to maintain the balance and stability of the system. The application of the phase regulating switch can achieve flexible power flow control and adjust the relative power flow direction between each node in the power system.

[0038] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the present invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A winding connection structure of a step-down phase-shifting distribution transformer, characterized in that: include: A transformer winding connection structure, wherein the transformer is a three-phase structure, an iron core column is arranged inside the transformer, and two phase-adjusting windings (1), an excitation winding (2), a voltage-adjusting winding (3) and a low-voltage winding (4) are sleeved on the iron core column; An excitation winding (2) and a voltage regulating winding (3) are connected in series to form a high-voltage voltage regulating unit, and the three-phase high-voltage voltage regulating units are connected end to end to form a triangle connection, and the triangle connection includes three vertices; The phase-adjusting winding (1) comprises a high-voltage side and a low-voltage side, both the high-voltage side and the low-voltage side are equipped with voltage regulating switches, and the three vertices are respectively connected to the three-phase phase-adjusting winding (1); The low voltage winding (4) comprises phase a, phase b, phase c and a zero phase, and the low voltage side of the three-phase phase-modulating winding (1) is respectively connected to the connection terminals of the three-phase low voltage winding (4); the three-phase low voltage winding (4) is star-connected.

2. The winding connection structure of a step-down phase-shifting distribution transformer according to claim 1 is characterized in that: The transformer is powered by high voltage on both sides, and the connection between the high and low voltages is a Dy connection, where Dy stands for Delta-Y connection.

3. The winding connection structure of a step-down phase-shifting distribution transformer according to claim 2 is characterized in that: The clock sequence number between the high voltage side and the low voltage side of the transformer is consistent with the number of the distribution transformer.

4. The winding connection structure of a step-down phase-shifting distribution transformer according to claim 3 is characterized in that: The connection between the two sides of the transformer is a delta-connected symmetrical phase-shifting structure.

5. The winding connection structure of a step-down phase-shifting distribution transformer according to claim 4 is characterized in that: A phase-adjusting switch is installed on the high-voltage side of the phase-adjusting winding (1), and the phase-adjusting switch is used to change the phase difference of the voltage between the two sides.

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