A closed-loop transformer based on a single-core asymmetric phase-shifting transformer and its control method.

Abstract

This invention discloses a loop-closing transformer based on a single-core asymmetrical phase-shifting transformer and its control method. The loop-closing transformer includes a single-core asymmetrical phase-shifting transformer bank and a voltage-regulating transformer bank. One end of the primary winding of the single-core asymmetrical phase-shifting transformer is connected to a three-phase power supply, and the middle tap serves as the output terminal of the single-core asymmetrical phase-shifting transformer, connected to the primary side of the voltage-regulating transformer. The secondary winding of the single-core asymmetrical phase-shifting transformer is delta-connected. The other end of the primary winding of the voltage-regulating transformer is grounded. One end of the secondary winding of the voltage-regulating transformer is directly led out as the output terminal of the loop-closing transformer, and the other end is grounded. Compared with the prior art, this invention can achieve amplitude-phase decoupling adjustment of the voltage phasor difference on both sides of the loop-closing point. The control law and control method are simple, with simple wiring, flexible adjustment methods, and a large adjustment range and high adjustment accuracy.

Description

Technical Field

[0001] This invention relates to the field of 10kV distribution network loop switching technology, and in particular to a loop-connecting transformer based on a single-core asymmetrical phase-shifting transformer and its control method. Background Technology

[0002] With the rapid development of the national economy, electricity users have increasingly higher requirements for power supply reliability. Since the distribution network directly faces electricity users, its structural design, operation mode, and maintenance methods are all key factors directly affecting power supply reliability. Currently, China's distribution network mainly adopts a closed-loop design and open-loop operation power supply mode. Under normal power supply mode, the interconnecting switches between lines are in the open state, which makes the distribution network typically operate in a radial pattern. When certain lines need maintenance or faults require load switching, in the past, grid dispatchers would usually perform a short-term power outage, restoring power after the load switch was completed. This would lead to short-term power outages for electricity users.

[0003] As users increasingly demand higher power quality and grid security and stability, in order to maintain the public image of power grid companies, grid dispatchers and operators usually try their best to fulfill users' wishes to perform load switching or line maintenance without power interruption. Therefore, achieving uninterrupted load switching through loop closing and unclosing operations has become an indispensable part of distribution network operation.

[0004] The significant benefits of implementing live-loop operation in distribution networks include reduced power outage time for users, ensured power supply reliability, and improved user satisfaction with power company services. However, as distribution network structures become increasingly complex, the parameters of the two busbars required for live-loop operation often fail to meet the conditions for live-loop operation. Voltage differences exist on both sides of the live-loop point, as do differences in the equivalent impedance of the live-loop path. During live-loop operation, significant live-loop currents, including steady-state currents and inrush currents, may be generated in the live-loop path. The steady-state current generated during live-loop operation may trigger overcurrent protection of the relay protection device, while the inrush current may trigger instantaneous overcurrent protection of the relay protection device.

[0005] Therefore, when a distribution network performs a loop-closing operation, it may cause overload of distribution lines, which in severe cases could even burn out electrical equipment. It may also trigger relay protection devices to malfunction, leading to power outages in larger areas. In the most serious cases, it could even endanger the lives of power workers, posing a significant threat to the economic and safe operation of the power grid. Therefore, it is necessary to design a device that can decouple the amplitude and phase of the voltage phasor difference on both sides of the loop-closing point to solve the above problems.

[0006] Chinese invention patent CN114884410B discloses a loop-closing power regulation control method based on the polarity and tap position of a phase-shifting transformer. First, based on the amplitude and phase angle difference between the voltage to be regulated and the target voltage, the type of the adjustment vector diagram for the target phase voltage regulating winding and the target phase adjusting winding is determined. Then, based on the adjustment vector diagram, the polarity of the target phase voltage regulating winding and the target phase adjusting winding is determined, and the corresponding tap position is calculated. Finally, based on the determined polarity and tap position of the target phase voltage regulating winding and the target phase adjusting winding, the polarity and tap position of the target phase voltage regulating winding and the target phase adjusting winding of the phase-shifting transformer are adjusted to accurately regulate the phase angle and amplitude of the second bus voltage, making it as close as possible to the first bus voltage. This ensures that the voltage vector difference between the two power supplies is minimized during loop closure, achieving the goal of minimizing the loop closure current and thus achieving safe loop closure. Its shortcomings include dividing the regulation requirements into four categories, each corresponding to a different adjustment vector diagram, resulting in complex electrical connections between windings and limited anti-interference capability. Compared with Chinese invention patent CN114884410B, the present invention has a simple electrical connection relationship, can realize decoupling compensation adjustment of voltage phasor difference amplitude on both sides of the loop point, has a simple control law and control method, flexible adjustment method, large adjustment range and high adjustment accuracy. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a closed-loop transformer based on a single-core asymmetrical phase-shifting transformer and its control method. Specifically, it provides a closed-loop transformer consisting of a voltage-regulating transformer and a single-core asymmetrical phase-shifting transformer connected in series and its control method, in order to solve the problem of phasor difference in voltage on both sides of the closed-loop point mentioned in the background technology.

[0008] The present invention adopts the following technical solution. A first aspect of the present invention provides a closed-loop transformer based on a single-core asymmetrical phase-shifting transformer, the closed-loop transformer comprising:

[0009] Single-core asymmetrical phase-shifting transformer group and voltage regulating transformer group. The primary winding of the single-core asymmetrical phase-shifting transformer group is connected to the power supply. The secondary winding of each phase of the single-core asymmetrical phase-shifting transformer outputs a compensation voltage phasor perpendicular to the power supply of that phase.

[0010] A voltage regulating transformer bank is connected in series with a single-core asymmetrical phase-shifting transformer bank to change the voltage amplitude.

[0011] Preferably, the single-core asymmetrical phase-shifting transformer bank includes: a phase of a single-core asymmetrical phase-shifting transformer, a phase of a single-core asymmetrical phase-shifting transformer, and a phase of a single-core asymmetrical phase-shifting transformer; the voltage regulating transformer bank includes: a phase of a voltage regulating transformer, a phase of a voltage regulating transformer, and a phase of a voltage regulating transformer.

[0012] The output terminals of phases a, b, and c of a single-core asymmetrical phase-shifting transformer are connected to the primary phases of phases a, b, and c of a voltage regulating transformer.

[0013] The second terminal of the primary winding of phase A of the voltage regulating transformer is grounded; the first terminal of the secondary winding of phase A of the voltage regulating transformer is unconnected, and the conductor is directly led out as the output terminal U of phase A of the closed-loop transformer. La The second terminal is grounded;

[0014] The second terminal of the primary winding of phase B of the voltage regulating transformer is grounded; the first terminal of the secondary winding of phase B of the voltage regulating transformer is unconnected, and the conductor is directly led out as the output terminal U of phase B of the closed-loop transformer. Lb The second terminal is grounded;

[0015] The second terminal of the primary winding of phase C of the voltage regulating transformer is grounded; the first terminal of the secondary winding of phase C of the voltage regulating transformer is unconnected, and the wire is directly led out as the output terminal U of phase C of the closed-loop transformer. Lc The second terminal is grounded.

[0016] Preferably, the first terminal of the primary winding of phase a of the single-core asymmetrical phase-shifting transformer is unconnected, and the second terminal is connected to the phase a power supply U. Sa Directly connected, with the center tap serving as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a The first terminal of the primary winding of phase a of the voltage regulating transformer is connected to the first terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer and the second terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer; the second terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer and the first terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer are connected to the first terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer.

[0017] The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer is unconnected, and the second terminal is connected to the phase b power supply U. Sb Directly connected, with the center tap serving as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b The first terminal of the primary winding of phase b of the voltage regulating transformer is connected to the second terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer.

[0018] The first terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer is unconnected, and the second terminal is connected to the phase c power supply U. Sc Directly connected, with the center tap serving as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c It is connected to the first terminal of the primary winding of phase C of the voltage regulating transformer; the first terminal of the secondary winding of phase C of the single-core asymmetrical phase-shifting transformer is connected to the second terminal of the secondary winding of phase A of the single-core asymmetrical phase-shifting transformer.

[0019] Preferably, the first terminal of the primary winding of phase a of the single-core asymmetrical phase-shifting transformer is used as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a The first terminal of the primary winding of phase a of the voltage regulating transformer is connected, the second terminal is left unconnected, and the intermediate tap is connected to the phase a power supply U. Sa Directly connected;

[0020] The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b The first terminal of the primary winding of phase b of the voltage regulating transformer is connected, the second terminal is unconnected, and the intermediate tap is connected to the phase b power supply U. Sb Directly connected;

[0021] The first terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c The first terminal of the primary winding of phase C of the voltage regulating transformer is connected, the second terminal is unconnected, and the intermediate tap is connected to the phase C power supply U. Sc Directly connected.

[0022] Preferably, the first terminal of the primary winding of phase a of the single-core asymmetrical phase-shifting transformer is used as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a The first terminal of the primary winding of phase a of the voltage regulating transformer is connected, and the second terminal is connected to the phase a power supply U. Sa Direct connection, with the middle tap left unconnected;

[0023] The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b The first terminal of the primary winding of phase b of the voltage regulating transformer is connected, and the second terminal is connected to the phase b power supply U. Sb Direct connection, with the middle tap left unconnected;

[0024] The first terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c The first terminal of the primary winding of phase C of the voltage regulating transformer is connected, and the second terminal is connected to the phase C power supply U. Sc Connect directly, with the middle tap unconnected.

[0025] A second aspect of the present invention provides a control method for a closed-loop transformer based on a single-core asymmetrical phase-shifting transformer, comprising the following steps:

[0026] S1. Adjust the connection sequence and direction of the primary side terminals or the secondary side terminals in a single-core asymmetrical phase-shifting transformer.

[0027] S2. Adjust the actual number of turns connected to the secondary coil in the single-core asymmetrical phase-shifting transformer;

[0028] S3. To achieve the commutation of the closed-loop phase-shifting transformer.

[0029] Preferably, in step S1, the connection sequence and direction of the primary side terminals in the single-core asymmetrical phase-shifting transformer are adjusted as follows: the first terminal of the primary winding of phase a of the single-core asymmetrical phase-shifting transformer is connected to the phase a power supply U. Sa Directly connected, with the center tap serving as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a It is connected to the first terminal of the primary winding of phase a of the voltage regulating transformer, and the second terminal is left unconnected;

[0030] The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer is connected to the phase b power supply U. Sb Directly connected, with the center tap serving as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b It is connected to the first terminal of the primary winding of phase b of the voltage regulating transformer, and the second terminal is unconnected;

[0031] The first terminal of the primary winding of the c-phase of a single-core asymmetrical phase-shifting transformer is connected to the c-phase power supply U. Sc Directly connected, with the center tap serving as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1c It is connected to the first terminal of the primary winding of phase C of the voltage regulating transformer, and the second terminal is left unconnected.

[0032] Preferably, in step S1, the connection sequence and direction of the primary side terminals in the single-core asymmetrical phase-shifting transformer are adjusted as follows:

[0033] The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer is unconnected, and the intermediate tap is connected to the phase a power supply U. Sa Directly connected, the second terminal serves as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a It is connected to the first terminal of the primary winding of phase a of the voltage regulating transformer;

[0034] The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer is unconnected, and the intermediate tap is connected to the phase b power supply U. sb Directly connected, the second terminal serves as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b It is connected to the first terminal of the primary winding of phase b of the voltage regulating transformer;

[0035] The first terminal of the primary winding of phase C of a single-core asymmetrical phase-shifting transformer is unconnected, and the intermediate tap is connected to the phase C power supply U. scDirectly connected, the second terminal serves as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c It is connected to the first terminal of the primary winding of phase C of the voltage regulating transformer.

[0036] Preferably, in step S1, the connection sequence and direction of the secondary side terminals in the single-core asymmetrical phase-shifting transformer are adjusted as follows: the first terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer is directly connected to the second terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer; the second terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer; and the second terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer.

[0037] Preferably, in step S2, the actual number of turns connected to the secondary coil of the single-core asymmetrical phase-shifting transformer is the same as the actual number of turns connected to the secondary coil of the single-core asymmetrical phase-shifting transformer when the loop transformer is adjusted in the forward amplitude phase.

[0038] Preferably, the actual number of turns connected to the secondary winding in a single-core asymmetrical phase-shifting transformer during forward amplitude-phase adjustment is determined by the following steps:

[0039] S2.1 Establish a system of equations to describe the constraint relationship between the compensation voltage phasor output by the closed-loop transformer based on a single-core asymmetrical phase-shifting transformer and the actual number of turns connected to the secondary coil in the single-core asymmetrical phase-shifting transformer.

[0040] S2.2. Iteratively solve the ideal connection turns ratio of the secondary winding in a single-core asymmetrical phase-shifting transformer, and design the initial value of the primary-secondary turns ratio accordingly.

[0041] S2.3 To minimize the L2 norm of the difference between the compensated voltage vector output by the closed-loop transformer and the actual expected output voltage vector, the actual number of turns connected to the secondary winding in the single-core asymmetrical phase-shifting transformer is dynamically adjusted.

[0042] Preferably, when the three phases are symmetrical, the equations for phase a are as follows:

[0043]

[0044] in This represents the secondary side voltage of phase a of a single-core asymmetrical phase-shifting transformer. This represents the voltage of phase c of the power supply. This represents the voltage of phase b of the power supply. The primary voltage of phase a of a single-core asymmetrical phase-shifting transformer, k ETa This indicates the primary and secondary turns ratio of phase a of a single-core asymmetrical phase-shifting transformer. k represents the output voltage of phase a of a single-core asymmetrical phase-shifting transformer. STa This indicates the primary and secondary turns ratio of phase a of the voltage regulating transformer. This represents the output voltage of phase a of the closed-loop transformer. This indicates the phase angle difference.

[0045] Preferably, step S3 uses a lookup table method for control, as follows:

[0046] Solve for the turns ratio iteration values ​​of each phase secondary winding coil in a single-core asymmetrical phase-shifting transformer;

[0047] A simulation model of a closed-loop transformer based on a single-core asymmetric phase-shifting transformer is built. Different voltage phasor differences are set on both sides of the closed-loop point. The turns ratio iteration value is used as the simulation parameter value. The simulation waveform or simulation data is observed. The L2 norm of the difference between the simulated output voltage phasor and the theoretically calculated output voltage phasor is compared to see if it is within the allowable error range. If it is, the theoretical derivation value is correct. If not, the equation set is wrong or the iterative solution value is incorrect. The derivation or solution should be repeated.

[0048] If the theoretical derivation is correct, the corresponding simulation data will be recorded in the table. When the closed-loop transformer based on the single-core asymmetrical phase-shifting transformer is actually put into operation, the actual number of turns connected to the secondary coil of each phase of the single-core asymmetrical phase-shifting transformer will be dynamically adjusted according to the voltage phasor difference on both sides of the closed-loop point detected in real time and the optimal turns ratio data of each phase secondary coil of the single-core asymmetrical phase-shifting transformer will be selected by looking up the table.

[0049] Preferably, step S3 is controlled by a controller, specifically as follows:

[0050] Design a closed-loop control algorithm;

[0051] When the closed-loop transformer based on the single-core asymmetrical phase-shifting transformer is put into operation, the voltage phasor difference on both sides of the closed-loop point is obtained in real time. This phasor difference is used as a parameter input to the controller. The controller calculates and outputs control commands in real time according to the pre-designed closed-loop control algorithm, thereby dynamically adjusting the actual number of turns connected to the secondary coil of each phase of the single-core asymmetrical phase-shifting transformer in real time.

[0052] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0053] 1. The closed-loop transformer designed in this invention is based on a single-core asymmetrical phase-shifting transformer. That is, the closed-loop transformer is composed of a voltage regulating transformer and a single-core asymmetrical phase-shifting transformer connected in series. The single-core asymmetrical phase-shifting transformer outputs a compensation voltage phasor perpendicular to the power supply of that phase on the secondary side of each phase. Then, the voltage amplitude is changed by the voltage regulating transformer group to realize the amplitude and phase decoupling compensation adjustment of the voltage phasors on both sides of the closed-loop point. The compensation method is more flexible and precise, and the actual closed-loop effect is more ideal.

[0054] 2. The compensation voltage phasor output by this invention is a voltage phasor perpendicular to the corresponding phase power supply in the three-phase power supply, and the topology and electrical connection relationship between the windings are relatively simple.

[0055] 3. By designing a suitable primary-secondary turns ratio of a single-core asymmetrical phase-shifting transformer and a voltage regulating transformer, this invention can inject a compensation voltage phasor with controllable phase angle and amplitude under no-load and load conditions. By dynamically adjusting the actual number of turns connected to the secondary coil of the single-core asymmetrical phase-shifting transformer and the primary-secondary turns ratio of the voltage regulating transformer, the desired compensation voltage phasor can be output. This can achieve decoupling compensation adjustment of the voltage phasor difference amplitude on both sides of the loop point. The control law and control method are simple, the adjustment method is flexible, the adjustment range is large, and the adjustment accuracy is high. Attached Figure Description

[0056] Figure 1 This is a topology of a closed-loop transformer based on a single-core asymmetric phase-shifting transformer;

[0057] Figure 2 This is a diagram showing the input-output voltage vector relationship of a closed-loop transformer based on a single-core asymmetric phase-shifting transformer during forward amplitude-phase adjustment.

[0058] Figure 3 This is a diagram showing the input-output voltage vector relationship of a closed-loop transformer based on a single-core asymmetrical phase-shifting transformer during negative amplitude-phase adjustment.

[0059] Figure 4 A PSCAD simulation diagram of a loop transformer based on a single-core asymmetric phase-shifting transformer;

[0060] Figure 5 This is a simulation waveform of the output voltage amplitude of phase a of a closed-loop transformer based on a single-core asymmetrical phase-shifting transformer.

[0061] Figure 6 The simulation waveform of the phase angle of the output voltage of phase a of a closed-loop transformer based on a single-core asymmetrical phase-shifting transformer is shown.

[0062] Figure 7 This is a simulation waveform of the a-phase line current of a closed-loop transformer based on a single-core asymmetric phase-shifting transformer. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0064] like Figure 1 As shown, Embodiment 1 of the present invention provides a closed-loop transformer based on a single-core asymmetrical phase-shifting transformer. Specifically, it is a closed-loop transformer consisting of a voltage-regulating transformer and a single-core asymmetrical phase-shifting transformer connected in series, including: a single-core asymmetrical phase-shifting transformer group and a voltage-regulating transformer group; the single-core asymmetrical phase-shifting transformer group includes: single-core asymmetrical phase-shifting transformer phase a, single-core asymmetrical phase-shifting transformer phase b, and single-core asymmetrical phase-shifting transformer phase c; the voltage-regulating transformer group includes: voltage-regulating transformer phase a, voltage-regulating transformer phase b, and voltage-regulating transformer phase c.

[0065] One end of the primary winding of a single-core asymmetrical phase-shifting transformer is connected to a three-phase power supply, while the other end is unconnected. The intermediate tap serves as the output terminal of the single-core asymmetrical phase-shifting transformer and is connected to the primary side of a voltage-regulating transformer. Alternatively, one end of the primary winding of the single-core asymmetrical phase-shifting transformer is connected to a three-phase power supply, while the other end serves as the output terminal of the single-core asymmetrical phase-shifting transformer and is connected to the primary side of a voltage-regulating transformer. The intermediate tap is unconnected. The secondary winding of the single-core asymmetrical phase-shifting transformer is delta-connected. The other end of the primary winding of the voltage-regulating transformer is grounded. One end of the secondary winding of the voltage-regulating transformer is directly led out as the output terminal of the loop transformer, while the other end is grounded.

[0066] Specifically, the connection relationship of the closed-loop transformer is as follows:

[0067] The second terminal of the primary winding of phase A of the voltage regulating transformer is grounded; the first terminal of the secondary winding of phase A of the voltage regulating transformer is unconnected, and the conductor is directly led out as the output terminal U of phase A of the closed-loop transformer. La The second terminal is grounded;

[0068] The second terminal of the primary winding of phase B of the voltage regulating transformer is grounded; the first terminal of the secondary winding of phase B of the voltage regulating transformer is unconnected, and the conductor is directly led out as the output terminal U of phase B of the closed-loop transformer. Lb The second terminal is grounded;

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

[0070] The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer is unconnected, and the second terminal is connected to the phase a power supply U. Sa Directly connected, with the center tap serving as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a The first terminal of the primary winding of phase a of the voltage regulating transformer is connected to the first terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer and the second terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer; the second terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer and the first terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer are connected to the first terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer.

[0071] The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer is unconnected, and the second terminal is connected to the phase b power supply U. Sb Directly connected, with the center tap serving as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b It is connected to the first terminal of the primary winding of phase b of the voltage regulating transformer; the first terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer is connected to the second terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer; the second terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer is connected to the first terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer.

[0072] The first terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer is unconnected, and the second terminal is connected to the phase c power supply U. Sc Directly connected, with the center tap serving as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c It is connected to the first terminal of the primary winding of phase C of the voltage regulating transformer; the first terminal of the secondary winding of phase C of the single-core asymmetrical phase-shifting transformer is connected to the second terminal of the secondary winding of phase A of the single-core asymmetrical phase-shifting transformer, and the second terminal of the secondary winding of phase C of the single-core asymmetrical phase-shifting transformer is connected to the first terminal of the secondary winding of phase A of the single-core asymmetrical phase-shifting transformer.

[0073] Each phase of a single-core asymmetrical phase-shifting transformer outputs a voltage compensation phasor perpendicular to the power supply of that phase. Through the primary-secondary turns ratio of the single-core asymmetrical phase-shifting transformer, the voltage compensation phasor is connected as the output of the single-core asymmetrical phase-shifting transformer to a voltage regulating transformer. Then, the voltage regulating transformer performs amplitude transformation on the voltage compensation phasor of the single-core asymmetrical phase-shifting transformer, thereby realizing the adjustment of the voltage amplitude and phase value of each phase output terminal of the closed-loop transformer.

[0074] In three-phase symmetry, the vector relationship between the compensation voltage phasors of each phase and the input and output voltage phasors of each phase is as follows: Figure 2As shown, the closed-loop transformer described in this embodiment is in positive amplitude-phase regulation. Taking phase a as an example, the output of phase a of the single-core asymmetrical phase-shifting transformer is a voltage compensation phasor perpendicular to the phase a power supply. Through the primary and secondary turns ratio of the single-core asymmetrical phase-shifting transformer, the voltage compensation phasor is connected as the output of the single-core asymmetrical phase-shifting transformer to the voltage regulating transformer. Then, the voltage regulating transformer performs amplitude transformation on the voltage compensation phasor of the single-core asymmetrical phase-shifting transformer, thereby realizing the voltage U at the output terminal of phase a of the closed-loop transformer based on the single-core asymmetrical phase-shifting transformer. La Adjustment of amplitude and phase values.

[0075] It should be noted that, Figure 1 The closed-loop transformer shown is based on a single-core asymmetrical phase-shifting transformer. The equivalent topology of this closed-loop transformer, consisting of a voltage-regulating transformer and a single-core asymmetrical phase-shifting transformer connected in series, is only one preferred but non-limiting implementation of the present invention. Changing the connection method of the primary winding of the single-core asymmetrical phase-shifting transformer can yield the following two additional configurations:

[0076] (1) Wiring method 1:

[0077] The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a The first terminal of the primary winding of phase a of the voltage regulating transformer is connected, the second terminal is left unconnected, and the intermediate tap is connected to the phase a power supply U. Sa Directly connected;

[0078] The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b The first terminal of the primary winding of phase b of the voltage regulating transformer is connected, the second terminal is unconnected, and the intermediate tap is connected to the phase b power supply U. Sb Directly connected;

[0079] The first terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c The first terminal of the primary winding of phase C of the voltage regulating transformer is connected, the second terminal is unconnected, and the intermediate tap is connected to the phase C power supply U. Sc Directly connected;

[0080] (2) Wiring method 2:

[0081] The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a The first terminal of the primary winding of phase a of the voltage regulating transformer is connected, and the second terminal is connected to the phase a power supply U. sa Direct connection, with the middle tap left unconnected;

[0082] The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1y The first terminal of the primary winding of phase b of the voltage regulating transformer is connected, and the second terminal is connected to the phase b power supply U. Sb Direct connection, with the middle tap left unconnected;

[0083] The first terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c The first terminal of the primary winding of phase C of the voltage regulating transformer is connected, and the second terminal is connected to the phase C power supply U. Sc Connect directly, with the middle tap unconnected.

[0084] In a loop transformer consisting of a voltage regulating transformer and a single-core asymmetrical phase-shifting transformer connected in series, the single-core asymmetrical phase-shifting transformer outputs a compensation voltage phasor for each phase, and the voltage regulating transformer then adjusts the amplitude. This phase adjustment followed by amplitude adjustment enables phase-amplitude decoupling compensation, and the compensation for voltage phasor differences on both sides of various loop closing points is more flexible and precise, resulting in a more ideal actual loop closing effect.

[0085] Embodiment 2 of the present invention provides a control method for a closed-loop transformer based on a single-core asymmetrical phase-shifting transformer, comprising the following steps:

[0086] S1. Adjust the connection sequence and direction of the primary side terminals or the secondary side terminals in a single-core asymmetrical phase-shifting transformer.

[0087] Specifically, in step S1, the connection sequence and direction of the primary side terminals in the single-core asymmetrical phase-shifting transformer are adjusted as follows:

[0088] The second terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer is unconnected, and the first terminal is connected to the phase a power supply U. Sa Directly connected, with the center tap serving as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a It is connected to the first terminal of the primary winding of phase a of the voltage regulating transformer;

[0089] The second terminal of the primary winding of phase b of the single-core asymmetrical phase-shifting transformer is unconnected, and the first terminal is connected to the phase b power supply U. Sb Directly connected, with the center tap serving as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b It is connected to the first terminal of the primary winding of phase b of the voltage regulating transformer;

[0090] The second terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer is unconnected, and the first terminal is connected to the phase c power supply U. ScDirectly connected, with the center tap serving as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c It is connected to the first terminal of the primary winding of phase C of the voltage regulating transformer.

[0091] In another embodiment, step S1 involves adjusting the connection sequence and direction of the primary side terminals in the single-core asymmetrical phase-shifting transformer as follows:

[0092] The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer is unconnected, and the intermediate tap is connected to the phase a power supply U. Sa Directly connected, the second terminal serves as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a It is connected to the first terminal of the primary winding of phase a of the voltage regulating transformer;

[0093] The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer is unconnected, and the intermediate tap is connected to the phase b power supply U. 2b Directly connected, the second terminal serves as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b It is connected to the first terminal of the primary winding of phase b of the voltage regulating transformer;

[0094] The first terminal of the primary winding of phase C of a single-core asymmetrical phase-shifting transformer is unconnected, and the intermediate tap is connected to the phase C power supply U. Sc Directly connected, the second terminal serves as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c It is connected to the first terminal of the primary winding of phase C of the voltage regulating transformer.

[0095] In another embodiment, step S1 involves adjusting the connection sequence and direction of the secondary side terminals in the single-core asymmetrical phase-shifting transformer as follows:

[0096] The first terminal of the secondary winding of phase A of the single-core asymmetrical phase-shifting transformer is directly connected to the second terminal of the secondary winding of phase C of the single-core asymmetrical phase-shifting transformer; the second terminal of the secondary winding of phase A of the single-core asymmetrical phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase B of the single-core asymmetrical phase-shifting transformer; the second terminal of the secondary winding of phase B of the single-core asymmetrical phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase C of the single-core asymmetrical phase-shifting transformer.

[0097] S2. Adjust the actual number of turns connected to the secondary coil in the single-core asymmetrical phase-shifting transformer;

[0098] Furthermore, in step S2, the actual number of turns connected to the secondary winding of the single-core asymmetrical phase-shifting transformer is the same as the actual number of turns connected to the secondary winding of the single-core asymmetrical phase-shifting transformer when the loop transformer is adjusted in the forward amplitude-phase regulation. That is, by adjusting the tap position and changing the primary-secondary turns ratio, the calculation method is as follows:

[0099] S2.1 Establish a system of equations to describe the constraint relationship between the compensation voltage phasor output of the closed-loop transformer based on a single-core asymmetrical phase-shifting transformer and the actual number of turns connected to the secondary winding in the single-core asymmetrical phase-shifting transformer. Since the closed-loop transformer operates symmetrically in three phases, only one phase needs to be analyzed. Taking phase a as an example, the relevant system of equations is as follows:

[0100]

[0101] in:

[0102] This represents the secondary side voltage of phase a of a single-core asymmetrical phase-shifting transformer.

[0103] This represents the voltage of phase c of the power supply.

[0104] This represents the voltage of phase b of the power supply.

[0105] The primary side voltage of phase a of a single-core asymmetrical phase-shifting transformer.

[0106] k ETa This indicates the primary and secondary turns ratio of phase a of a single-core asymmetrical phase-shifting transformer.

[0107] This represents the output voltage of phase a of a single-core asymmetrical phase-shifting transformer.

[0108] k STa This indicates the primary and secondary turns ratio of phase a of the voltage regulating transformer.

[0109] This represents the output voltage of phase a of the closed-loop transformer.

[0110] This indicates the phase angle difference.

[0111] S2.2. Iteratively solve the ideal connection turns ratio of the secondary winding in a single-core asymmetrical phase-shifting transformer, and design the initial value of the primary-secondary turns ratio accordingly.

[0112] S2.3 To minimize the L2 norm of the difference between the compensated voltage vector output by the closed-loop transformer and the actual desired output voltage vector, the actual number of turns connected to the secondary coil in the single-core asymmetrical phase-shifting transformer is dynamically adjusted. This allows for real-time and dynamic precise compensation of the voltage phasor difference on both sides of the closed-loop point, thereby achieving shock-free closed-loop power supply.

[0113] It is worth noting that the control methods for single-core phase-shifting transformers can be divided into two main categories:

[0114] The first type involves table lookup. Theoretically, each voltage phasor difference (on both sides of the loop closure point) corresponds to a voltage compensation phasor, which in turn corresponds to the actual number of turns connected to the secondary windings of each phase of a single-core asymmetrical phase-shifting transformer. First, the turns ratio iteration value of each phase of the single-core asymmetrical phase-shifting transformer is calculated. Then, a corresponding simulation model of the loop-closure transformer is built in PSCAD, setting different voltage phasor differences on both sides of the loop closure point. The turns ratio iteration value is used as the simulation parameter value, and the simulation waveform or data is observed. The L2 norm of the difference between the simulated output voltage phasor and the theoretically calculated output voltage phasor is compared to see if it is within the allowable error range. This verifies the correctness of the theoretically calculated turns ratio of each phase of the single-core asymmetrical phase-shifting transformer. If, regardless of how the desired compensation voltage phasor changes, the error between the simulation data obtained by using the iterative solution value as the simulation parameter value and the theoretically derived value is within the allowable range, then the theoretical derivation is correct. If the error is not within the allowable range, then the theoretical derivation may be incorrect or the iterative solution value is faulty. If there are no errors, record the corresponding simulation data in the table. When the closed-loop transformer is actually put into operation, the turns ratio data of each phase secondary coil of the single-core asymmetrical phase-shifting transformer can be selected by referring to the table based on the real-time detected voltage phasor difference on both sides of the closed-loop point. The taps of each phase secondary coil of the single-core asymmetrical phase-shifting transformer can be dynamically adjusted to accurately compensate for the voltage phasor difference on both sides of the closed-loop point, so as to achieve fast, shock-free, and safe closed-loop operation.

[0115] S3. To achieve the commutation of the closed-loop phase-shifting transformer.

[0116] The following is a verification example of a set of turns ratios: the closed-loop parameter settings and some theoretically calculated parameter values ​​are shown in columns 1 and 2 of Table 1.

[0117] Table 1. Parameter settings and simulation data for the flexible loop closing device.

[0118]

[0119] in This represents the effective value of the output voltage at phase a of the closed-loop transformer. This represents the effective value of phase a power supply. This represents the effective value of the current in phase a.

[0120] Build such in PSCAD Figure 4 The transformer model shown is based on a single-core asymmetrical phase-shifting transformer. The simulated waveform of the output voltage amplitude of phase a of the closed-loop transformer is as follows: Figure 5 As shown, the verification formula is: Where u La,p The peak value of phase a; the simulated waveform of the phase a output voltage phase angle of the closed-loop transformer based on a single-core asymmetrical phase-shifting transformer is as follows. Figure 6As shown; the simulation waveform of the a-phase line current of the closed-loop transformer based on a single-core asymmetrical phase-shifting transformer is as follows. Figure 7 As shown, the errors between the simulation data and the theoretical derivation values ​​are all within the allowable range. Therefore, the theoretical calculation values ​​of a set of turns ratios of each phase secondary winding of the single-core asymmetrical phase-shifting transformer are correct. The corresponding data are recorded in Table 1.

[0121] The second category is the controller: designing a closed-loop control algorithm for the closed-loop transformer body. When the closed-loop transformer is actually put into operation, the voltage phasor difference on both sides of the closing point is obtained by real-time detection. This phasor difference is used as a parameter input to the controller. The controller calculates in real time according to the pre-designed closed-loop control algorithm and outputs control commands, thereby dynamically adjusting a set of actual connected turns of each phase secondary winding of the single-core asymmetrical phase-shifting transformer in real time, so as to achieve dynamic and accurate compensation of the voltage phasor difference on both sides of the closing point.

[0122] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A closed-loop transformer based on a single-core asymmetrical phase-shifting transformer, characterized in that, The closed-loop transformer includes: Single-core asymmetrical phase-shifting transformer group and voltage regulating transformer group. The primary winding of the single-core asymmetrical phase-shifting transformer group is connected to the power supply. The secondary winding of each phase of the single-core asymmetrical phase-shifting transformer outputs a compensation voltage phasor perpendicular to the power supply of that phase. A voltage regulating transformer bank is connected in series with a single-core asymmetrical phase-shifting transformer bank to change the voltage amplitude. The single-core asymmetrical phase-shifting transformer group includes: single-core asymmetrical phase-shifting transformers a-phase, b-phase, and c-phase; the voltage regulating transformer group includes: voltage regulating transformers a-phase, b-phase, and c-phase. The output terminals of phases a, b, and c of a single-core asymmetrical phase-shifting transformer are connected to the primary phases of phases a, b, and c of a voltage regulating transformer. The second terminal of the primary winding of phase A of the voltage regulating transformer is grounded; the first terminal of the secondary winding of phase A of the voltage regulating transformer is unconnected, and the conductor is directly led out as the output terminal U of phase A of the closed-loop transformer. La The second terminal is grounded; The second terminal of the primary winding of phase B of the voltage regulating transformer is grounded; the first terminal of the secondary winding of phase B of the voltage regulating transformer is unconnected, and the conductor is directly led out as the output terminal U of phase B of the closed-loop transformer. Lb The second terminal is grounded; The second terminal of the primary winding of phase C of the voltage regulating transformer is grounded; the first terminal of the secondary winding of phase C of the voltage regulating transformer is unconnected, and the wire is directly led out as the output terminal U of phase C of the closed-loop transformer. Lc The second terminal is grounded; Each phase of the single-core asymmetrical phase-shifting transformer outputs a compensation voltage phasor, which is then adjusted by a voltage regulating transformer to achieve amplitude-phase decoupling compensation and to compensate for the voltage phasor difference on both sides of the loop closing point.

2. A closed-loop transformer based on a single-core asymmetric phase-shifting transformer according to claim 1, characterized in that: The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer is unconnected, and the second terminal is connected to the phase a power supply U. Sa Directly connected, with the center tap serving as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a The first terminal of the primary winding of phase a of the voltage regulating transformer is connected to the first terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer and the second terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer; the second terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer and the first terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer are connected to the first terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer. The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer is unconnected, and the second terminal is connected to the phase b power supply U. Sb Directly connected, with the center tap serving as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b The first terminal of the primary winding of phase b of the voltage regulating transformer is connected to the second terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer. The first terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer is unconnected, and the second terminal is connected to the phase c power supply U. Sc Directly connected, with the center tap serving as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c It is connected to the first terminal of the primary winding of phase C of the voltage regulating transformer.

3. A closed-loop transformer based on a single-core asymmetric phase-shifting transformer according to claim 1, characterized in that: The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a The first terminal of the primary winding of phase a of the voltage regulating transformer is connected, the second terminal is left unconnected, and the intermediate tap is connected to the phase a power supply U. Sa Directly connected; The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b The first terminal of the primary winding of phase b of the voltage regulating transformer is connected, the second terminal is unconnected, and the intermediate tap is connected to the phase b power supply U. Sb Directly connected; The first terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c The first terminal of the primary winding of phase C of the voltage regulating transformer is connected, the second terminal is unconnected, and the intermediate tap is connected to the phase C power supply U. Sc Directly connected.

4. A closed-loop transformer based on a single-core asymmetric phase-shifting transformer according to claim 1, characterized in that: The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a The first terminal of the primary winding of phase a of the voltage regulating transformer is connected, and the second terminal is connected to the phase a power supply U. Sa Direct connection, with the middle tap left unconnected; The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b The first terminal of the primary winding of phase b of the voltage regulating transformer is connected, and the second terminal is connected to the phase b power supply U. Sb Direct connection, with the middle tap left unconnected; The first terminal of the primary winding of phase c of a single-core asymmetrical phase-shifting transformer serves as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c The first terminal of the primary winding of phase C of the voltage regulating transformer is connected, and the second terminal is connected to the phase C power supply U. Sc Connect directly, with the middle tap unconnected.

5. A control method for a loop transformer based on a single-core asymmetrical phase-shifting transformer according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Adjust the connection sequence and direction of the primary side terminals or the secondary side terminals in a single-core asymmetrical phase-shifting transformer. S2. Adjust the actual number of turns connected to the secondary coil in the single-core asymmetrical phase-shifting transformer; S3. Perform commutation of the closed-loop transformer.

6. The control method for a loop transformer based on a single-core asymmetrical phase-shifting transformer according to claim 5, characterized in that: In step S1, the connection sequence and direction of the primary side terminals in the single-core asymmetrical phase-shifting transformer are adjusted as follows: The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer is connected to the phase a power supply U. Sa Directly connected, with the center tap serving as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a It is connected to the first terminal of the primary winding of phase a of the voltage regulating transformer, and the second terminal is left unconnected; The first terminal of the primary winding of phase b of a single-core asymmetrical phase-shifting transformer is connected to the phase b power supply U. Sb Directly connected, with the center tap serving as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b It is connected to the first terminal of the primary winding of phase b of the voltage regulating transformer, and the second terminal is unconnected; The first terminal of the primary winding of the c-phase of a single-core asymmetrical phase-shifting transformer is connected to the c-phase power supply U. Sc Directly connected, with the center tap serving as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1c It is connected to the first terminal of the primary winding of phase C of the voltage regulating transformer, and the second terminal is left unconnected.

7. The control method for a loop transformer based on a single-core asymmetrical phase-shifting transformer according to claim 5, characterized in that: In step S1, the connection sequence and direction of the primary side terminals in the single-core asymmetrical phase-shifting transformer are adjusted as follows: The first terminal of the primary winding of phase a of a single-core asymmetrical phase-shifting transformer is unconnected, and the intermediate tap is connected to the phase a power supply U. Sa Directly connected, the second terminal serves as the output terminal U of phase a of the single-core asymmetrical phase-shifting transformer. 1a It is connected to the first terminal of the primary winding of phase a of the voltage regulating transformer; The first terminal of the primary winding of phase b of the single-core asymmetrical phase-shifting transformer is unconnected, and the intermediate tap is connected to the phase b power supply U. Sb Directly connected, the second terminal serves as the output terminal U of phase b of the single-core asymmetrical phase-shifting transformer. 1b It is connected to the first terminal of the primary winding of phase b of the voltage regulating transformer; The first terminal of the primary winding of phase C of a single-core asymmetrical phase-shifting transformer is unconnected, and the intermediate tap is connected to the phase C power supply U. Sc Directly connected, the second terminal serves as the output terminal U of phase c of the single-core asymmetrical phase-shifting transformer. 1c It is connected to the first terminal of the primary winding of phase C of the voltage regulating transformer.

8. The control method for a loop transformer based on a single-core asymmetrical phase-shifting transformer according to claim 5, characterized in that: In step S1, the connection sequence and direction of the secondary side terminals in the single-core asymmetrical phase-shifting transformer are adjusted as follows: the first terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer is directly connected to the second terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer; the second terminal of the secondary winding of phase a of the single-core asymmetrical phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer; and the second terminal of the secondary winding of phase b of the single-core asymmetrical phase-shifting transformer is directly connected to the first terminal of the secondary winding of phase c of the single-core asymmetrical phase-shifting transformer.

9. The control method for a loop transformer based on a single-core asymmetrical phase-shifting transformer according to claim 5, characterized in that: In step S2, the actual number of turns connected to the secondary coil of the single-core asymmetrical phase-shifting transformer is the same as the actual number of turns connected to the secondary coil of the single-core asymmetrical phase-shifting transformer when the loop transformer is adjusted in the forward amplitude phase.

10. The control method for a loop transformer based on a single-core asymmetrical phase-shifting transformer according to claim 9, characterized in that: The actual number of turns connected to the secondary winding in a single-core asymmetrical phase-shifting transformer during forward amplitude-phase adjustment is determined by the following steps: S2.1 Establish a system of equations to describe the constraint relationship between the compensation voltage phasor output by the closed-loop transformer based on a single-core asymmetrical phase-shifting transformer and the actual number of turns connected to the secondary coil in the single-core asymmetrical phase-shifting transformer. S2.

2. Iteratively solve the ideal connection turns ratio of the secondary winding in a single-core asymmetrical phase-shifting transformer, and design the initial value of the primary-secondary turns ratio accordingly. S2.3 To minimize the L2 norm of the difference between the compensated voltage vector output by the closed-loop transformer and the actual expected output voltage vector, the actual number of turns connected to the secondary winding in the single-core asymmetrical phase-shifting transformer is dynamically adjusted.

11. The control method for a loop transformer based on a single-core asymmetrical phase-shifting transformer according to claim 10, characterized in that: When the three phases are symmetrical, the equations for phase a are as follows: in This represents the secondary side voltage of phase a of a single-core asymmetrical phase-shifting transformer. This represents the voltage of phase c of the power supply. This represents the voltage of phase b of the power supply. This represents the voltage of phase a of the power supply. k represents the primary voltage of phase a of a single-core asymmetrical phase-shifting transformer. ETa This indicates the primary and secondary turns ratio of phase a of a single-core asymmetrical phase-shifting transformer. k represents the output voltage of phase a of a single-core asymmetrical phase-shifting transformer. STa This indicates the primary and secondary turns ratio of phase a of the voltage regulating transformer. This represents the output voltage of phase a of the closed-loop transformer. This indicates the phase angle difference.

12. The control method for a loop transformer based on a single-core asymmetrical phase-shifting transformer according to claim 5, characterized in that: Step S3 uses a lookup table method for control, as follows: Solve for the turns ratio iteration values ​​of each phase secondary winding coil in a single-core asymmetrical phase-shifting transformer; A simulation model of a closed-loop transformer based on a single-core asymmetric phase-shifting transformer is built. Different voltage phasor differences are set on both sides of the closed-loop point. The turns ratio iteration value is used as the simulation parameter value. The simulation waveform or simulation data is observed. The L2 norm of the difference between the simulated output voltage phasor and the theoretically calculated output voltage phasor is compared to see if it is within the allowable error range. If it is, the theoretical derivation value is correct. If not, the equation set is wrong or the iterative solution value is incorrect. The derivation or solution should be repeated. If the theoretical derivation is correct, the corresponding simulation data will be recorded in the table. When the closed-loop transformer based on the single-core asymmetrical phase-shifting transformer is actually put into operation, the turns ratio data of each phase secondary winding of the single-core asymmetrical phase-shifting transformer will be selected by looking up the table based on the real-time detected voltage phasor difference on both sides of the closed-loop point, and the actual number of turns connected to each phase secondary winding of the single-core asymmetrical phase-shifting transformer will be dynamically adjusted.

13. The control method for a loop transformer based on a single-core asymmetrical phase-shifting transformer according to claim 5, characterized in that: Step S3 is controlled by a controller, as follows: Design a closed-loop control algorithm; When the closed-loop transformer based on the single-core asymmetrical phase-shifting transformer is put into operation, the voltage phasor difference on both sides of the closed-loop point is obtained in real time. This phasor difference is used as a parameter input to the controller. The controller calculates and outputs control commands in real time according to the pre-designed closed-loop control algorithm, thereby dynamically adjusting the actual number of turns connected to the secondary coil of each phase of the single-core asymmetrical phase-shifting transformer in real time.

Images