Loop closing transformer based on single-core symmetrical phase-shifting transformer and control method thereof

Abstract

The invention discloses a closed-loop transformer based on a single-core symmetric phase-shifting transformer and a control method thereof. The control method comprises the following steps: establishing a target closed-loop transformer, and establishing a first connection strategy and a first access strategy based on the target closed-loop transformer; acquiring a first control target of the target loop closing transformer; and based on the first control target, the target loop closing transformer is controlled in combination with the first connection strategy and the first access strategy. By adopting the structure that the single-core symmetrical phase-shifting transformer bank and the voltage-regulating transformer bank are connected in series, the amplitude-phase decoupling regulation of the voltage phasor difference on the two sides of a loop closing point is realized, the control rule and mode are simpler, the wiring is simple and convenient, the regulation is flexible, and the regulation range is wider and the regulation precision is higher.

Description

Technical Field

[0001] The present invention relates to the technical field of 10KV distribution network closed-loop power transfer, and particularly relates to a closed-loop transformer based on a single-core symmetric phase-shifting transformer and a control method thereof. Background Art

[0002] With the rapid development of the national economy, the power demand of power users and the requirement for power supply reliability are getting higher and higher. Since the distribution network is directly facing power users, its structural design, operation mode and maintenance method will all be key factors directly affecting power supply reliability. Due to reasons such as cost and technology, for a long time, the distribution network in China has mainly adopted the mode of "closed-loop design and open-loop operation". This power supply mode cannot cope with the short-term power outage and closed-loop current impact problems brought by switching operations. Realizing flexible closed-loop operation of the distribution network is considered an effective means to solve the above problems and an important direction for the development of technologies in this field.

[0003] The significant advantage of the live closed-loop operation of the distribution network is that it reduces the power outage time of users, guarantees the reliability of power supply, and improves the satisfaction of users with the services of power enterprises. However, with the increasing complexity of the distribution network structure, it is difficult for the parameters of the two busbars on both sides that actually need to perform closed-loop operations to meet the closed-loop conditions. There is a voltage difference between the two sides of the closed-loop point, and there are differences in the equivalent impedance of the closed-loop path. A relatively large closed-loop current, including steady-state current and impact current, may be generated in the closed-loop path during the closed-loop operation. The steady-state current generated during the closed-loop process may trigger the over-current protection action of the relay protection device, and the impact current may also trigger the quick-break protection action of the relay protection. Therefore, it is necessary to design a device that can realize amplitude-phase decoupling regulation of the voltage phasor difference between the two sides of the closed-loop point to solve the above problems. Summary of the Invention

[0004] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and title of the specification of this application, to avoid obscuring the purpose of this part, the abstract and the title. However, such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above existing problems, the present invention is proposed.

[0006] Therefore, the present invention provides a closed-loop transformer based on a single-core symmetric phase-shifting transformer and a control method thereof, which can solve the problems mentioned in the background art.

[0007] To solve the above technical problems, the present invention provides the following technical solutions:

[0008] In the first aspect, the present invention provides a closed-loop transformer based on a single-core symmetric phase-shifting transformer, including:

[0009] The closed-loop transformer includes a single-core symmetric phase-shifting transformer bank and a voltage regulating transformer bank;

[0010] The voltage regulating transformer bank is connected in series with the single-core symmetric phase-shifting transformer bank;

[0011] The primary side coil of the single-core symmetric phase-shifting transformer bank is connected to the power supply;

[0012] Each secondary side coil of the single-core symmetric phase-shifting transformer outputs a compensation voltage phasor perpendicular to the voltage of the center tap of the primary side coil of this phase.

[0013] In a second aspect, the present invention provides a control method for a closed-loop transformer based on a single-core symmetric phase-shifting transformer, including:

[0014] Establish a first connection strategy and a first access strategy based on the target closed-loop transformer;

[0015] Obtain the first control target of the target closed-loop transformer;

[0016] Based on the first control target, combine the first connection strategy and the first access strategy to control the target closed-loop transformer.

[0017] As a preferred solution of the control method for a closed-loop transformer based on a single-core symmetric phase-shifting transformer according to the present invention, wherein: the first connection strategy includes:

[0018] The first-level connection strategy for the primary side connection terminals;

[0019] The second-level connection strategy for the secondary side connection terminals;

[0020] Both the first-level connection strategy and the second-level connection strategy at least include the configuration of the connection sequence and the connection direction.

[0021] As a preferred solution of the control method for a closed-loop transformer based on a single-core symmetric phase-shifting transformer according to the present invention, wherein: the first access strategy includes:

[0022] Establish a first constraint equation set;

[0023] The first constraint equation set is used to describe the constraint relationship between the compensation voltage phasor output by the closed-loop transformer based on the single-core symmetric phase-shifting transformer and the actual number of turns accessed by the secondary side coil in the single-core symmetric phase-shifting transformer.

[0024] As a preferred solution of the control method for a closed-loop transformer based on a single-core symmetric phase-shifting transformer according to the present invention, wherein: the first access strategy further includes:

[0025] Establish a first objective function;

[0026] The first objective function is any function that minimizes the two-norm of the difference between the compensated voltage vector output by the closed-loop transformer and the actually expected output voltage vector;

[0027] Solve the first objective function;

[0028] Dynamically adjust the actual number of turns of the secondary side coil in the single-core symmetric phase-shifting transformer according to the solution result of the first objective function.

[0029] As a preferred scheme of the control method of the closed-loop transformer based on the single-core symmetric phase-shifting transformer of the present invention, wherein: the control of the target closed-loop transformer based on the first control objective, combined with the first connection strategy and the first access strategy includes:

[0030] Based on the first control objective, combined with the first connection strategy and the first access strategy, solve the iterative value of the turns ratio of each phase secondary winding coil in the single-core symmetric phase-shifting transformer;

[0031] Judge whether the theoretically deduced value is correct according to the iterative value of the turns ratio;

[0032] If the theoretically deduced value is correct, use the look-up table method for control.

[0033] As a preferred scheme of the control method of the closed-loop transformer based on the single-core symmetric phase-shifting transformer of the present invention, wherein: the control of the target closed-loop transformer based on the first control objective, combined with the first connection strategy and the first access strategy further includes:

[0034] Based on the first control objective, combined with the first connection strategy and the first access strategy, design a closed-loop control algorithm;

[0035] When the closed-loop transformer based on the single-core symmetric phase-shifting transformer is actually put into operation, obtain the voltage phasor difference on both sides of the closed-loop point through real-time detection, and input this phasor difference as a parameter into the controller;

[0036] The controller calculates and outputs control instructions in real time according to the pre-designed closed-loop control algorithm, and then dynamically adjusts the actual number of turns of each phase secondary coil of the single-core symmetric phase-shifting transformer in real time.

[0037] As a preferred scheme of the control method of the closed-loop transformer based on the single-core symmetric phase-shifting transformer of the present invention, wherein: the first connection strategy and the first access strategy include:

[0038] The first connection strategy is used to adjust the connection sequence and connection direction of the primary side terminal in the single-core symmetric phase-shifting transformer and the secondary side terminal in the single-core symmetric phase-shifting transformer;

[0039] The first access strategy is used to adjust the actual number of turns of the secondary side coil in the single-core symmetric phase-shifting transformer.

[0040] In a third aspect, the present invention provides a computer device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the method described above are implemented.

[0041] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described above are implemented.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention proposes a closed-loop transformer based on a single-core symmetric phase-shifting transformer and its control method, establishing a first connection strategy and a first access strategy based on the target closed-loop transformer; obtaining a first control target of the target closed-loop transformer; and controlling the target closed-loop transformer based on the first control target in combination with the first connection strategy and the first access strategy. By adopting a structure in which a single-core symmetric phase-shifting transformer bank is connected in series with a voltage regulating transformer bank, amplitude-phase decoupling adjustment of the voltage phasor difference on both sides of the closed-loop point is realized. Specifically, the single-core symmetric phase-shifting transformer bank can output a compensation voltage phasor perpendicular to the voltage of the middle tap of the primary side coil. By adjusting the actual number of turns of the secondary side coil, the output compensation voltage phasor can be accurately controlled, so as to achieve the purpose of adjusting the voltage phasor difference on both sides of the closed-loop point. At the same time, in combination with the first connection strategy and the second access strategy, efficient and flexible control of the closed-loop transformer can be realized, improving the reliability and safety of the closed-loop operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0044] Figure 1 is a method flow chart of a closed-loop transformer based on a single-core symmetric phase-shifting transformer and its control method provided by an embodiment of the present invention;

[0045] Figure 2 is a schematic topological structure diagram of a closed-loop transformer based on a single-core symmetric phase-shifting transformer provided by an embodiment of the present invention;

[0046] Figure 3Vector relationship diagram of input and output voltages during positive amplitude-phase regulation of the single-core symmetric phase-shifting transformer of a closed-loop transformer and its control method provided by an embodiment of the present invention;

[0047] Figure 4 Vector relationship diagram of input and output voltages during negative amplitude-phase regulation of the single-core symmetric phase-shifting transformer of a closed-loop transformer and its control method provided by an embodiment of the present invention;

[0048] Figure 5 PSCAD simulation diagram of the closed-loop transformer based on the single-core symmetric phase-shifting transformer of a closed-loop transformer and its control method provided by an embodiment of the present invention;

[0049] Figure 6 Simulated waveform diagram of the amplitude of the a-phase output voltage of the closed-loop transformer based on the single-core symmetric phase-shifting transformer of a closed-loop transformer and its control method provided by an embodiment of the present invention;

[0050] Figure 7 Simulated waveform diagram of the phase angle of the a-phase output voltage of the closed-loop transformer based on the single-core symmetric phase-shifting transformer of a closed-loop transformer and its control method provided by an embodiment of the present invention;

[0051] Figure 8 Simulated waveform diagram of the a-phase line current of the closed-loop transformer based on the single-core symmetric phase-shifting transformer of a closed-loop transformer and its control method provided by an embodiment of the present invention;

[0052] Figure 9 Internal structure diagram of a computer device of a closed-loop transformer and its control method based on a single-core symmetric phase-shifting transformer provided by an embodiment of the present invention. Detailed implementation manners

[0053] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following provides a detailed description of the specific implementation manners of the present invention with reference to the accompanying drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0054] Embodiment 1

[0055] Refer to Figures 1-9 , which is the first embodiment of the present invention. This embodiment provides a closed-loop transformer based on a single-core symmetric phase-shifting transformer and its control method, including:

[0056] In the existing related technologies, there are some problems. For example, a relatively large closing loop current may be generated during the closing loop operation, which includes steady-state current and impulse current. These currents may trigger the operation of the relay protection device, thus affecting the reliability and safety of power supply.

[0057] This application provides a method that can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to elaborate in detail how to implement the closing loop transformer based on the single-core symmetric phase-shifting transformer and its control method;

[0058] Figure 2 The schematic diagram of the topology structure of the closing loop transformer based on the single-core symmetric phase-shifting transformer is shown, including:

[0059] The closing loop transformer includes a single-core symmetric phase-shifting transformer bank and a voltage regulating transformer bank;

[0060] The voltage regulating transformer bank is connected in series with the single-core symmetric phase-shifting transformer bank;

[0061] The primary side coil of the single-core symmetric phase-shifting transformer bank is connected to the power supply;

[0062] Each secondary side coil of the single-core symmetric phase-shifting transformer outputs a compensation voltage phasor perpendicular to the voltage at the middle tap of the corresponding primary side coil.

[0063] The single-core symmetric phase-shifting transformer bank and the voltage regulating transformer bank are transformers composed of three phases a, b, and c of the transformer, so they are called transformer banks.

[0064] In the embodiment of this application, as Figure 2 shown, the closing loop transformer is composed of a voltage regulating transformer and a single-core symmetric phase-shifting transformer connected in series, including the single-core symmetric phase-shifting transformer bank and the voltage regulating transformer bank; the single-core symmetric phase-shifting transformer bank includes: single-core symmetric phase-shifting transformer phase a, single-core symmetric phase-shifting transformer phase b, and single-core symmetric phase-shifting transformer phase c; the voltage regulating transformer bank includes: voltage regulating transformer phase a, voltage regulating transformer phase b, and voltage regulating transformer phase c.

[0065] In the embodiment of this application, one end of the primary side winding of the single-core symmetric phase-shifting transformer is connected to the three-phase power supply, and the other end is used as the output end of the single-core symmetric phase-shifting transformer and is connected to the primary side of the voltage regulating transformer. The three-phase power supply and the output of the single-core symmetric phase-shifting transformer are symmetric according to the middle tap of the primary side winding, and the middle tap is regularly connected to the secondary side winding of the single-core symmetric phase-shifting transformer;

[0066] In the embodiment of this application, the secondary side winding of the single-core symmetric phase-shifting transformer is connected in a delta connection;

[0067] In the embodiment of the present application, the other end of the primary side winding of the voltage regulating transformer is grounded. One end of the wire of the secondary side winding of the voltage regulating transformer is directly led out as the output end of the closed-loop transformer, and the other end is grounded.

[0068] Specifically, the connection relationship of the closed-loop transformer is as follows:

[0069] The second terminal of the a-phase primary side winding of the voltage regulating transformer is grounded; the first terminal of the a-phase secondary side winding of the voltage regulating transformer is left unconnected, and the wire is directly led out as the output end U of the a-phase of the closed-loop transformer La , and the second terminal is grounded;

[0070] The second terminal of the b-phase primary side winding of the voltage regulating transformer is grounded; the first terminal of the b-phase secondary side winding of the voltage regulating transformer is left unconnected, and the wire is directly led out as the output end U of the b-phase of the closed-loop transformer Lb , and the second terminal is grounded;

[0071] The second terminal of the c-phase primary side winding of the voltage regulating transformer is grounded; the first terminal of the c-phase secondary side winding of the voltage regulating transformer is left unconnected, and the wire is directly led out as the output end U of the c-phase of the closed-loop transformer Lc , and the second terminal is grounded.

[0072] In the embodiment of the present application, the first terminal of the a-phase primary side winding of the single-core symmetric phase-shifting transformer serves as the output end U of the a-phase of the single-core symmetric phase-shifting transformer 1a and is connected to the first terminal of the a-phase primary side winding of the voltage regulating transformer. The second terminal is directly connected to the a-phase power supply U Sa and is directly connected. The center tap is connected to the second terminal of the c-phase secondary side winding of the single-core symmetric phase-shifting transformer;

[0073] In the embodiment of the present application, the first terminal of the a-phase secondary side winding of the single-core symmetric phase-shifting transformer is connected to the second terminal of the b-phase secondary side winding of the single-core symmetric phase-shifting transformer, and the second terminal of the a-phase secondary side winding of the single-core symmetric phase-shifting transformer is connected to the first terminal of the c-phase secondary side winding of the single-core symmetric phase-shifting transformer;

[0074] In the embodiment of the present application, the first terminal of the b-phase primary side winding of the single-core symmetric phase-shifting transformer serves as the output end U of the b-phase of the single-core symmetric phase-shifting transformer 1b and is connected to the first terminal of the b-phase primary side winding of the voltage regulating transformer. The second terminal is directly connected to the b-phase power supply U Sb and is directly connected. The center tap is connected to the second terminal of the a-phase secondary side winding of the single-core symmetric phase-shifting transformer;

[0075] In the embodiment of the present application, the first terminal of the secondary winding of phase b of the single-core symmetric phase-shifting transformer is connected to the second terminal of the secondary winding of phase c of the single-core symmetric phase-shifting transformer, and the second terminal of the secondary winding of phase b of the single-core symmetric phase-shifting transformer is connected to the first terminal of the secondary winding of phase a of the single-core symmetric phase-shifting transformer;

[0076] In the embodiment of the present application, the first terminal of the primary winding of phase c of the single-core symmetric phase-shifting transformer serves as the output terminal U of phase c of the single-core symmetric phase-shifting transformer 1c and is connected to the first terminal of the primary winding of phase c of the regulating transformer, and the second terminal is directly connected to the phase c power supply U Sc and the center tap is connected to the second terminal of the secondary winding of phase b of the single-core symmetric phase-shifting transformer;

[0077] In the embodiment of the present application, the first terminal of the secondary winding of phase c of the single-core symmetric phase-shifting transformer is connected to the first terminal of the secondary winding of phase a of the single-core symmetric phase-shifting transformer, and the second terminal of the secondary winding of phase c of the single-core symmetric phase-shifting transformer is connected to the first terminal of the secondary winding of phase b of the single-core symmetric phase-shifting transformer.

[0078] In the embodiment of the present application, each phase of the single-core symmetric phase-shifting transformer outputs a voltage compensation phasor perpendicular to the voltage of the center tap of the primary winding of the single-core symmetric phase-shifting transformer. Through the turns ratio of the primary and secondary sides of the single-core symmetric phase-shifting transformer, the voltage compensation phasor is used as the output of the single-core symmetric phase-shifting transformer and connected to the regulating transformer. Then, through the regulating transformer, the amplitude of the voltage compensation phasor of the single-core symmetric phase-shifting transformer is transformed, so as to realize the adjustment of the voltage amplitude and phase values of the output terminals of each phase of the closed-loop transformer.

[0079] In an alternative embodiment, when three-phase symmetry exists, the vector relationship between the compensation voltage phasors of each phase and the input and output voltage phasors of each phase is as Figure 3 shown. The closed-loop transformer in this embodiment is in positive amplitude-phase regulation. Taking phase a as an example, the single-core symmetric phase-shifting transformer of phase a outputs a voltage compensation phasor perpendicular to the voltage of the center tap of the primary winding of the single-core symmetric phase-shifting transformer of phase a. Through the turns ratio of the primary and secondary sides of the single-core symmetric phase-shifting transformer, the voltage compensation phasor is used as the output of the single-core symmetric phase-shifting transformer and connected to the regulating transformer. Then, through the regulating transformer, the amplitude of the voltage compensation phasor of the single-core symmetric phase-shifting transformer is transformed, so as to realize the adjustment of the voltage amplitude and phase values of the output terminal U La of phase a of the closed-loop transformer based on the single-core symmetric phase-shifting transformer.

[0080] It should be noted that Figure 3 is the output voltage leading the input voltage, Figure 4 and is the output voltage lagging behind the input voltage ( Figure 4 that is, the vector relationship after the commutation operation is performed. Commutation means ΔUa opposite to the original ΔU a in the opposite direction, i.e., 180°). Taking phase a as an example, "for each secondary side coil of the single-core symmetric phase-shifting transformer, a compensation voltage phasor perpendicular to the voltage at the center tap of the primary side coil of this phase is output respectively". The voltage at the center tap here is U in the figure va , and the compensation voltage phasor here is ΔU a , due to the connection relationship of the transformer, the two are perpendicular. The input voltage U Sa superimposed with ΔU a is the output voltage U of the single-core symmetric phase-shifting transformer 1a , and then through the regulating transformer, a transformation ratio in terms of amplitude is obtained to get U La , which is the output voltage of the entire closed-loop transformer

[0081] It should be noted that in the closed-loop transformer in which the regulating transformer and the single-core symmetric phase-shifting transformer are connected in series, each phase of the single-core symmetric phase-shifting transformer outputs a section of compensation voltage phasor, and then the regulating transformer performs amplitude adjustment. In this way, phase adjustment first and then amplitude adjustment can achieve amplitude-phase decoupling compensation, and it is more flexible and accurate to compensate the voltage phasor differences on both sides of various closed-loop points, and the actual closed-loop effect is more ideal

[0082] Embodiment 2

[0083] In a preferred embodiment Figure 1 a method flow chart of a closed-loop transformer based on a single-core symmetric phase-shifting transformer and its control method is shown, including

[0084] S101: Establish a first connection strategy and a first access strategy based on the target closed-loop transformer

[0085] In the embodiments of the present application, the first connection strategy and the first access strategy include

[0086] The first connection strategy is used to adjust the connection sequence and connection direction of the primary side connection terminals in the single-core symmetric phase-shifting transformer and the secondary side connection terminals in the single-core symmetric phase-shifting transformer

[0087] The first access strategy is used to adjust the actual number of turns of the secondary side coil accessed in the single-core symmetric phase-shifting transformer

[0088] In an alternative embodiment, the first connection strategy can be flexibly designed according to the specific structural characteristics of the single-core symmetric phase-shifting transformer and the requirements of the target closed-loop transformer. For example, by changing the connection sequence of the connection terminals, the phase adjustment of the voltage phasor can be achieved; by changing the connection direction, the flexibility of control can be further increased

[0089] In an alternative embodiment, the first access strategy adjusts the amplitude of the output compensated voltage phasor by precisely controlling the number of turns of the secondary side coil connected. The selection of the number of turns can be calculated according to the specific situation of the voltage phasor difference on both sides of the loop closing point to achieve precise amplitude compensation.

[0090] It should be noted that in practical applications, the first connection strategy and the first access strategy can cooperate with each other to jointly achieve efficient and flexible control of the loop closing transformer.

[0091] In the embodiment of the present application, the first connection strategy includes:

[0092] The first - level connection strategy for the primary - side connection terminals;

[0093] The second - level connection strategy for the secondary - side connection terminals;

[0094] Both the first - level connection strategy and the second - level connection strategy at least include the configuration of the connection sequence and connection direction.

[0095] In an alternative embodiment, the first - level connection strategy mainly involves how to specifically set the connection sequence and connection direction of the primary - side connection terminals and the secondary - side connection terminals according to the structural characteristics of the single - core symmetric phase - shifting transformer and the requirements of the target loop closing transformer.

[0096] In an alternative embodiment, the first - level connection strategy may also include connecting the primary - side connection terminals to the power supply or other related devices in a specific sequence and direction to ensure the correct input of the voltage phasor and phase adjustment.

[0097] In an alternative embodiment, the second - level connection strategy focuses on the configuration of the secondary - side connection terminals, which are connected to the voltage - regulating transformer and are responsible for outputting the compensated voltage phasor.

[0098] In an alternative embodiment, in the second - level connection strategy, it is necessary to carefully consider how to connect the secondary - side connection terminals in an optimal way so as to precisely control the amplitude of the output compensated voltage phasor by adjusting the number of turns connected subsequently.

[0099] In the embodiment of the present application, the first - level connection strategy is used to adjust the connection sequence and connection direction of the primary - side connection terminals in the single - core symmetric phase - shifting transformer, specifically as follows:

[0100] The first connection terminal of the primary - side winding of phase a of the single - core symmetric phase - shifting transformer is directly connected to the phase - a power supply U Sa and the second connection terminal is used as the output terminal U of phase a of the single - core symmetric phase - shifting transformer 1a and is connected to the first connection terminal of the primary - side winding of phase a of the voltage - regulating transformer;

[0101] The first terminal of the primary winding of phase b of the single-core symmetric phase-shifting transformer is directly connected to the phase b power supply U Sb The second terminal serves as the output terminal U of phase b of the single-core symmetric phase-shifting transformer 1b and is connected to the first terminal of the primary winding of phase b of the voltage regulating transformer;

[0102] The first terminal of the primary winding of phase c of the single-core symmetric phase-shifting transformer is directly connected to the phase c power supply U Sc The second terminal serves as the output terminal U of phase c of the single-core symmetric phase-shifting transformer 1c and is connected to the first terminal of the primary winding of phase c of the voltage regulating transformer.

[0103] In the embodiment of the present application, the second-level connection strategy is used to adjust the connection sequence and connection direction of the primary-side terminals and secondary-side terminals in the single-core symmetric phase-shifting transformer, specifically as follows:

[0104] The middle tap of the primary winding of phase a of the single-core symmetric phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase c of the single-core symmetric phase-shifting transformer;

[0105] The first terminal of the secondary winding of phase a of the single-core symmetric phase-shifting transformer is directly connected to the second terminal of the secondary winding of phase c of the single-core symmetric phase-shifting transformer;

[0106] The second terminal of the secondary winding of phase a of the single-core symmetric phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase b of the single-core symmetric phase-shifting transformer;

[0107] The middle tap of the primary winding of phase b of the single-core symmetric phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase a of the single-core symmetric phase-shifting transformer;

[0108] The second terminal of the secondary winding of phase b of the single-core symmetric phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase c of the single-core symmetric phase-shifting transformer;

[0109] The middle tap of the primary winding of phase c of the single-core symmetric phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase b of the single-core symmetric phase-shifting transformer.

[0110] In the embodiment of the present application, the first access strategy includes:

[0111] Establish a first constraint equation set;

[0112] The first constraint equation set is used to describe the constraint relationship between the compensated voltage phasor output by the closed-loop transformer based on the single-core symmetric phase-shifting transformer and the actual number of turns of the secondary-side coil in the single-core symmetric phase-shifting transformer.

[0113] In an alternative embodiment, the first set of constraint equations can be established through mathematical formulas or physical laws, specifically considering factors such as the electrical characteristics of the single-core symmetric phase-shifting transformer, the number of turns of the secondary coil connected, and the desired compensation voltage phasor.

[0114] It should be noted that these sets of equations can ensure that in actual operation, by adjusting the number of turns connected, the desired compensation voltage phasor can be accurately obtained, thereby meeting the control requirements of the closed-loop transformer.

[0115] In an alternative embodiment, the first set of constraint equations can be solved based on the electrical characteristics of the single-core symmetric phase-shifting transformer and the desired compensation voltage phasor. By adjusting the number of turns of the secondary coil connected, precise control of the compensation voltage phasor can be achieved. This control method is not only flexible but also capable of achieving efficient amplitude-phase compensation to ensure the smooth progress of the closed-loop operation.

[0116] In the embodiment of the present application, the first access strategy further includes:

[0117] Establish a first objective function;

[0118] The first objective function is any function that minimizes the two-norm of the difference between the compensation voltage vector output by the closed-loop transformer and the actually desired output voltage vector;

[0119] Solve the first objective function;

[0120] Dynamically adjust the actual number of turns of the secondary coil in the single-core symmetric phase-shifting transformer according to the solution result of the first objective function.

[0121] In an alternative embodiment, the first objective function can be set in the form of a function based on the least squares method or other optimization algorithms. This function aims to minimize the difference between the compensation voltage vector actually output by the closed-loop transformer and the target desired voltage vector. By iteratively solving this objective function, the optimal configuration of the number of turns of the secondary coil connected can be obtained, thereby ensuring that the closed-loop transformer can accurately output the required voltage vector.

[0122] Specifically, the actual number of turns of the secondary coil in the single-core symmetric phase-shifting transformer is the actual number of turns of the secondary coil in the single-core symmetric phase-shifting transformer during the forward amplitude-phase adjustment of the closed-loop transformer, that is, by adjusting the tap position to change the turns ratio of the primary and secondary sides. The calculation method is as follows:

[0123] Establish a first set of constraint equations to describe the constraint relationship between the compensation voltage phasor output by the closed-loop transformer based on the single-core symmetric phase-shifting transformer and the actual number of turns of the secondary coil in the single-core symmetric phase-shifting transformer. Due to the three-phase symmetric operation of the closed-loop transformer, only one phase needs to be analyzed. Taking phase a as an example, when three-phase symmetry exists, the relevant equations for phase a are as follows:

[0124]

[0125] Among them, represents the output terminal voltage of phase a of the single-core symmetric phase-shifting transformer, represents the power supply voltage of phase a, is the compensation voltage output by phase a of the single-core symmetric phase-shifting transformer, represents the phase-shifting angle, represents the intermediate tap voltage of the primary side of phase a of the single-core symmetric phase-shifting transformer, represents the output terminal voltage of phase a of the closed-loop transformer, k STa represents the turns ratio of the primary and secondary sides of phase a of the voltage regulating transformer, represents the output terminal voltage of phase b of the single-core symmetric phase-shifting transformer, represents the output terminal voltage of phase c of the single-core symmetric phase-shifting transformer.

[0126] Furthermore, the ideal access turn ratio of the secondary side coil in the single-core symmetric phase-shifting transformer is iteratively solved, and thus the initial value of the turns ratio of the primary and secondary sides is designed;

[0127] Furthermore, in order to minimize the two-norm of the difference between the compensation voltage vector output by the closed-loop transformer and the actually expected output voltage vector, the actual access turns of the secondary side coil in the single-core symmetric phase-shifting transformer are dynamically adjusted, and then the voltage phasor difference on both sides of the closed-loop point is accurately compensated in real time and dynamically to achieve shock-free closed-loop power transfer.

[0128] In the embodiment of the present application, the specific form of the first objective function is not limited, and as long as it is a related function that minimizes the two-norm of the difference between the compensation voltage vector output by the closed-loop transformer and the actually expected output voltage vector, it should fall within the protection scope of the present application.

[0129] It should be noted that establishing the first connection strategy and the first access strategy based on the target closed-loop transformer can ensure that in the subsequent steps, by accurately controlling the connection sequence and connection direction of the primary side wiring terminal and the secondary side wiring terminal in the single-core symmetric phase-shifting transformer, and the actual access turns of the secondary side coil, the accurate adjustment of the amplitude-phase value of the output terminal voltage of the closed-loop transformer is realized. The formulation of this strategy provides a solid foundation for the amplitude-phase compensation in the subsequent steps, making the entire control process more efficient, flexible and accurate. At the same time, through the mutual cooperation of the first connection strategy and the first access strategy, the flexible adjustment of the output terminal voltage of the closed-loop transformer can be realized, meeting the requirements in different application scenarios, and improving the reliability and stability of the closed-loop operation.

[0130] S102: Obtain the first control target of the target closed-loop transformer;

[0131] In an alternative embodiment, the first control objective may be the commutation operation of the closed-loop phase-shifting transformer, i.e., adjusting the direction of the voltage phasor output by the closed-loop transformer according to actual needs. For example, in some power systems, it may be necessary for the voltage phasor output by the closed-loop transformer to be in the opposite direction to the original system voltage phasor to achieve reverse power flow or reverse reactive power compensation. At this time, the commutation operation of the voltage phasor output by the closed-loop transformer can be achieved by adjusting the connection sequence or direction of the terminals in the single-core symmetric phase-shifting transformer and the number of turns of the secondary side coil connected.

[0132] In the embodiment of the present application, the first control objective is the commutation operation of the closed-loop phase-shifting transformer.

[0133] It should be noted that obtaining the first control objective of the target closed-loop transformer can accurately formulate a control strategy based on actual needs and optimize the operation effect of the closed-loop transformer. For example, in scenarios where reverse power flow or reverse reactive power compensation is required, by precisely controlling the direction of the voltage phasor output by the closed-loop transformer, the stability and efficiency of the power system can be effectively improved.

[0134] In an alternative embodiment, after obtaining the first control objective, a specific control scheme can be formulated according to the specific parameters and operating status of the target closed-loop transformer, in combination with the first connection strategy and the first access strategy.

[0135] It should be noted that this control scheme will describe in detail how to adjust the connection sequence and direction of the terminals in the single-core symmetric phase-shifting transformer and the number of turns of the secondary side coil connected to achieve the first control objective.

[0136] S103: Based on the first control objective, control the target closed-loop transformer in combination with the first connection strategy and the first access strategy.

[0137] In an alternative embodiment, controlling the target closed-loop transformer based on the first control objective, in combination with the first connection strategy and the first access strategy, may include:

[0138] Based on the first control objective, solve the iterative value of the transformation ratio of each phase secondary side winding coil in the single-core symmetric phase-shifting transformer in combination with the first connection strategy and the first access strategy;

[0139] Judge whether the theoretically deduced value is correct according to the iterative value of the transformation ratio;

[0140] If the theoretically deduced value is correct, use the look-up table method for control.

[0141] Specifically, the look-up table method is used for control, and the specific method is as follows:

[0142] Solve the iterative value of the turns ratio of the secondary winding coils of each phase in the single-core symmetric phase-shifting transformer based on the first control objective, combined with the first connection strategy and the first access strategy;

[0143] Build a simulation model of the closed-loop transformer based on the single-core symmetric phase-shifting transformer, set the voltage phasor difference on both sides of different closed-loop points, use the iterative value of the turns ratio as the simulation parameter value, observe the simulation waveform or simulation data, and compare whether the two-norm of the difference between the simulation output voltage phasor and the theoretically calculated output voltage phasor is within the allowable error range. If so, it means that the theoretically derived value is correct; if not, it means that the equations are incorrect or the iterative solution value is incorrect, and re-derivation or solution is required;

[0144] If the theoretically derived value is correct, record the corresponding simulation data in a table. When the closed-loop transformer based on the single-core symmetric phase-shifting transformer is actually put into operation, according to the voltage phasor difference on both sides of the closed-loop point detected in real time, select the best turns ratio data of the secondary side coils of each phase of the single-core symmetric phase-shifting transformer according to the look-up table, and dynamically adjust the actual number of turns connected to the secondary side coils of each phase of the single-core symmetric phase-shifting transformer.

[0145] It should be noted that theoretically, for each (voltage phasor difference on both sides of the closed-loop point), there corresponds a voltage compensation phasor, which also corresponds to different actual number of turns connected to the secondary side coils of each phase of the single-core symmetric phase-shifting transformer.

[0146] First, solve the iterative value of the turns ratio of the secondary winding coils of each phase of the single-core symmetric phase-shifting transformer;

[0147] After that, build the corresponding simulation model of the closed-loop transformer in PSCAD, set the voltage phasor difference on both sides of different closed-loop points, use the iterative value of the turns ratio as the simulation parameter value, observe the simulation waveform or simulation data, and compare whether the two-norm of the difference between the simulation output voltage phasor and the theoretically calculated output voltage phasor is within the allowable error range, so as to verify the correctness of the theoretically calculated value of the turns ratio of the secondary side coils of each phase of the single-core symmetric phase-shifting transformer. If the error between the simulation data obtained with the iterative solution value as the simulation parameter value and the theoretically derived value is within the allowable range regardless of how the desired compensation voltage phasor changes, it means that the theoretical derivation is correct; if the error is not within the allowable range, it means that the theoretical derivation may be incorrect or the iterative solution value is incorrect.

[0148] If there is no error, record the corresponding simulation data in a table. When the closed-loop transformer is actually put into operation, according to the voltage phasor difference on both sides of the closed-loop point detected in real time, select the best turns ratio data of the secondary side coils of each phase of the single-core symmetric phase-shifting transformer according to the look-up table, and dynamically adjust the tap of the secondary side coils of each phase of the single-core symmetric phase-shifting transformer, so as to accurately compensate the voltage phasor difference on both sides of the closed-loop point and achieve fast and non-impact safe closed-loop.

[0149] In another alternative embodiment, the control of the target closed-loop transformer based on the first control objective, in combination with the first connection strategy and the first access strategy, may further include:

[0150] Design a closed-loop control algorithm based on the first control objective, in combination with the first connection strategy and the first access strategy;

[0151] When the closed-loop transformer based on the single-core symmetric phase-shifting transformer is actually put into operation, the voltage phasor difference on both sides of the closed-loop point is obtained through real-time detection, and this phasor difference is used as a parameter to input into the controller;

[0152] The controller calculates and outputs control instructions in real time according to the pre-designed closed-loop control algorithm, and then dynamically adjusts the actual number of turns of the secondary side coils of each phase of the single-core symmetric phase-shifting transformer in real time.

[0153] Specifically, design the closed-loop control algorithm of the closed-loop transformer body. When the closed-loop transformer is actually put into operation, the voltage phasor difference on both sides of the closed-loop point is obtained through real-time detection, and this phasor difference is used as a parameter to input into the controller. The controller calculates in real time according to the pre-designed closed-loop control algorithm and outputs control instructions, and then dynamically adjusts a set of actual number of turns of the secondary side coils of each phase of the single-core symmetric phase-shifting transformer in real time to achieve dynamic and accurate compensation of the voltage phasor difference on both sides of the closed-loop point.

[0154] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as Figure 9 shown. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a carrier network, NFC (Near Field Communication), or other technologies. The computer program, when executed by the processor, implements a control method for a closed-loop transformer based on a single-core symmetric phase-shifting transformer. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covered on the display screen, or a button, a trackball, or a touchpad provided on the housing of the computer device, or an external keyboard, touchpad, or mouse, etc.

[0155] This embodiment also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by the processor, the following steps are implemented:

[0156] Establish a first connection strategy and a first access strategy based on the target closed-loop transformer;

[0157] Obtain the first control objective of the target closed-loop transformer;

[0158] Based on the first control objective, combine the first connection strategy and the first access strategy to control the target closed-loop transformer.

[0159] Embodiment 3

[0160] Refer to Figures 5-8 , an embodiment of the present invention provides a closed-loop transformer based on a single-core symmetric phase-shifting transformer and its control method. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0161] The following is a set of verified turns ratio examples: The set values of the closed-loop parameters and the theoretical calculation values of some parameters are shown in the first column and the second column of Table 1:

[0162] Table 1 Parameter settings and simulation data table of the flexible closed-loop device

[0163]

[0164] Among them, k ETa represents the turns ratio of the primary and secondary sides of phase a of the single-core symmetric phase-shifting transformer, and k STa represents the turns ratio of the primary and secondary sides of phase a of the voltage regulating transformer. represents the effective value of the phase a power supply. represents the effective value of the voltage at the output end of phase a of the single-core symmetric phase-shifting transformer. represents the effective value of the voltage at the output end of phase a of the closed-loop transformer. represents the effective value of the phase a line current.

[0165] Build a transformer model as shown in Figure 5 in PSCAD. The simulation waveform of the amplitude of the output voltage of phase a of the closed-loop transformer based on the single-core symmetric phase-shifting transformer is as shown in Figure 6 . The verification formula is: Where is the peak value of the output voltage of phase a of the closed-loop transformer; The simulation waveform of the phase angle of the output voltage of phase a of the closed-loop transformer based on the single-core symmetric phase-shifting transformer is as shown in Figure 7 ; The simulation waveform of the phase a line current of the closed-loop transformer based on the single-core symmetric phase-shifting transformer is as shown in Figure 8 . The errors between the simulation data and the theoretically derived values are all within the allowable range. Therefore, the theoretically calculated values of a set of turns ratios of the secondary side coils of each phase of the single-core symmetric phase-shifting transformer are calculated correctly, and the corresponding data are recorded in Table 1.

[0166] The closed-loop transformer designed in this application based on a single-core symmetric phase-shifting transformer, that is, the closed-loop transformer formed by connecting a voltage regulating transformer and a single-core symmetric phase-shifting transformer in series, includes a single-core symmetric phase-shifting transformer and a voltage regulating transformer. Among them, the secondary side coils of each phase of the single-core symmetric phase-shifting transformer respectively output compensation voltage phasors perpendicular to the voltages at the center taps of the primary side coils of this phase. Then, the voltage amplitudes are changed through a voltage regulating transformer bank to achieve amplitude-phase decoupling compensation adjustment of the voltage phasors on both sides of the closed-loop point. The compensation method is more flexible and accurate, and the actual closed-loop effect is more ideal.

[0167] The compensation voltage phasors output in this application are compensation voltage phasors perpendicular to the voltages at the center taps of the primary side coils of each phase of the single-core symmetric phase-shifting transformer, and the topological structure and the electrical connection relationship between windings are relatively simple.

[0168] By designing appropriate turns ratios of the primary and secondary sides of the single-core symmetric phase-shifting transformer and the voltage regulating transformer in this application, compensation voltage phasors with controllable phase angles and amplitudes can be injected under no-load and load conditions. By dynamically adjusting the actual number of turns connected to the secondary side coils of the single-core symmetric phase-shifting transformer and the turns ratio of the primary and secondary sides of the voltage regulating transformer, the desired compensation voltage phasors can be output, and amplitude-phase decoupling compensation adjustment of the voltage phasor difference on both sides of the closed-loop point can be achieved. The control law and control method are simple, the adjustment method is flexible, the adjustment range is large, and the adjustment accuracy is high.

[0169] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

[0170] Those skilled in the art should understand that the embodiments of this application can be provided as a method, a system, or a computer program product. Therefore, this application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes. The solutions in the embodiments of this application can be implemented using various computer languages. For example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript.

[0171] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a means for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or a means for implementing the functions specified in multiple blocks.

[0172] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction means, and the instruction means implements the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or a means for implementing the functions specified in multiple blocks.

[0173] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or a means for implementing the functions specified in multiple blocks.

[0174] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0175] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these changes and modifications.

Claims

1. A ring transformer based on a single-core symmetrical phase-shifting transformer, characterized in that: include: The ring-closed transformer comprises a single-core symmetrical phase-shifting transformer group and a voltage-regulating transformer group; The voltage regulating transformer group is connected in series with the single-core symmetrical phase-shifting transformer group; The primary side coil of the single-core symmetrical phase-shifting transformer group is connected to a power supply; The secondary coil of each phase of the single-core symmetrical phase-shifting transformer outputs a compensation voltage phasor perpendicular to the middle tap voltage of the primary coil of the phase.

2. A control method for a ring-closing transformer based on a single-core symmetrical phase-shifting transformer, characterized in that: include: Establishing a first connection strategy and a first access strategy based on the target closed-loop transformer; Obtaining a first control target of a target closed-loop transformer; Based on the first control target, the target closed-loop transformer is controlled in combination with the first connection strategy and the first access strategy.

3. The control method of the ring-closed transformer based on the single-core symmetrical phase-shifting transformer according to claim 2 is characterized in that: The first connection strategy includes: First-level connection strategy for primary terminals; Second level connection strategy for secondary terminals; The first-level connection strategy and the second-level connection strategy both include at least the configuration of the connection sequence and the connection direction.

4. The control method of the ring-closed transformer based on the single-core symmetrical phase-shifting transformer according to claim 3 is characterized in that: The first access strategy includes: Establish the first set of constraint equations; The first set of constraint equations is used to describe the constraint relationship between the compensation voltage phasor output by the ring transformer based on the single-core symmetrical phase-shifting transformer and the actual number of connected turns of the secondary side coil in the single-core symmetrical phase-shifting transformer.

5. The control method of the ring-closed transformer based on the single-core symmetrical phase-shifting transformer according to claim 4 is characterized in that: The first access strategy also includes: Establish the first objective function; The first objective function is an arbitrary function that minimizes the second norm of the difference between the compensation voltage vector output by the loop transformer and the voltage vector actually expected to be output; solving the first objective function; The actual number of connected turns of the secondary side coil in the single-core symmetrical phase-shifting transformer is dynamically adjusted according to the solution result of the first objective function.

6. The control method of the ring-closed transformer based on the single-core symmetrical phase-shifting transformer according to claim 5, characterized in that: The controlling of the target closed-loop transformer based on the first control target and in combination with the first connection strategy and the first access strategy includes: Based on the first control target, in combination with the first connection strategy and the first access strategy, solving the transformation ratio iteration value of the secondary winding coil of each phase in the single-core symmetrical phase-shifting transformer; Judging that the theoretically derived value is correct according to the transformation ratio iteration value; If the theoretically derived value is correct, the table lookup method is used for control.

7. The control method of the ring-closing transformer based on the single-core symmetrical phase-shifting transformer according to claim 6 is characterized in that: The controlling of the target closed-loop transformer based on the first control target and in combination with the first connection strategy and the first access strategy also includes: Based on the first control objective, design a closed-loop control algorithm in combination with the first connection strategy and the first access strategy; When the ring-closing transformer based on the single-core symmetrical phase-shifting transformer is actually put into operation, the voltage phase difference on both sides of the closing point is obtained through real-time detection, and the phase difference is input into the controller as a parameter; The controller calculates and outputs control instructions in real time according to a pre-designed closed-loop control algorithm, and then dynamically adjusts the actual connected turns value of the secondary side coils of each phase of the single-core symmetrical phase-shifting transformer in real time.

8. The control method of the ring-closed transformer based on the single-core symmetrical phase-shifting transformer according to claim 7, characterized in that: The first connection strategy and the first access strategy include: The first connection strategy is used to adjust the connection sequence and connection direction of the primary side terminal in the single-core symmetrical phase-shifting transformer and the secondary side terminal in the single-core symmetrical phase-shifting transformer; The first access strategy is used to adjust the actual access turns of the secondary side coil in the single-core symmetrical phase-shifting transformer.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 2 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 2 to 8 are implemented.

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