Independently flexible regulated delta-hexagon phase-shifting transformer and control method thereof

Abstract

The application discloses a kind of independent flexible adjustment delta-hexagon type phase-shifting transformer and its control method, three excitation windings are alternately connected with three voltage regulating windings to form a ring structure, so that the excitation windings and the voltage regulating windings intersect with each other, the voltage regulating windings are connected with the excitation windings on both sides thereof through two polarity switches arranged thereon, forming a transformer with symmetrical structure, the symmetrical structure can enable the taps on both sides of the phase-shifting transformer to be adjusted independently during adjustment, and the rear gear does not need to be symmetrical after adjustment. The design can not only independently and flexibly adjust the amplitude and phase of the line voltage, but also has high adjustment precision, and can independently adjust the active power flow and the reactive power flow of the line.

Description

Technical Field

[0001] This invention relates to a phase-shifting transformer, and more particularly to an independently adjustable delta-hexagonal phase-shifting transformer and its control method. Background Technology

[0002] Due to the separation of energy centers and load centers, the power systems of many countries around the world, including my country, are developing in the direction of high voltage, large capacity, large scale, interconnection and long-distance power transmission, forming regional power grid interconnection. Regional power grid interconnection has improved the reliability of power supply, but it has also brought many problems, such as uneven power flow distribution, circulating current, etc., with some lines being heavily loaded while others have low utilization rates, affecting the safety of the power system and the consumption of new energy.

[0003] Existing power systems typically use phase-shifting transformers for power flow control. A phase-shifting transformer, also known as a phase angle regulator, adds a suitable voltage phasor to the input voltage of the original line, thereby changing the phase difference between the voltages on both sides of the line and rationally distributing power transmission, which can improve the safety and efficiency of power system operation.

[0004] Although existing phase-shifting transformers have advantages such as low cost, high reliability, and high efficiency, they still have the following drawbacks:

[0005] 1. Existing phase-shifting transformers are set according to voltage levels. When adjusting the phase angle, the taps on both sides of the winding operate together. At the same time, the taps on both sides must be adjusted symmetrically. They cannot independently and flexibly adjust the amplitude and phase of the line voltage, and the adjustment accuracy is low.

[0006] The information disclosed in this background section is intended only to enhance understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies, such as the inability to independently and flexibly adjust the amplitude and phase of the line voltage and low adjustment accuracy, and to provide a triangular-hexagonal phase-shifting transformer and its control method that can independently and flexibly adjust the amplitude and phase of the line voltage with high adjustment accuracy.

[0008] To achieve the above objectives, the technical solution of the present invention is:

[0009] An independently adjustable delta-hexagonal phase-shifting transformer, the phase-shifting transformer comprising: three excitation windings and three voltage regulating windings;

[0010] The three excitation windings are the three-phase windings of the phase-shifting transformer, and the three voltage regulating windings are respectively set to correspond to the three excitation windings. The three excitation windings and the three voltage regulating windings are all set on the same magnetic core. The three excitation windings and the three voltage regulating windings are alternately connected end to end to form a triangular-hexagonal connection structure.

[0011] The three excitation windings and the three voltage regulating windings have the same structure. Each voltage regulating winding is equipped with two on-load tap changers and two polarity switches. One on-load tap changer is on the grid side of the phase-shifting transformer, and the other is on the valve side. The excitation winding's turns are divided into two parts, each with an on-load tap changer. Each voltage regulating winding includes three polarity switch connection points. Two of these connection points are the terminals on both sides of the voltage regulating winding, and the third connection point is located in the middle of the winding. Each polarity switch includes an input pin and two output pins. The input pins of the two polarity switches are connected to their corresponding excitation winding sides. One output pin of each polarity switch is simultaneously connected to the polarity switch connection point in the middle of the voltage regulating winding, and the other output pin of each polarity switch is connected to both ends of the voltage regulating winding.

[0012] The phase-shifting transformer includes phase A, phase B, and phase C, and phase Y is any one of phases A, B, and C of the phase-shifting transformer. After the compensation voltage is injected through the phase-shifting transformer, the active power injected into phase Y of the phase-shifting transformer is... and reactive power The expression is:

[0013] (1)

[0014] In formula (1) This refers to the Y-phase grid-side voltage of the phase-shifting transformer. Inject compensation voltage from the Y-phase line into the phase-shifting transformer. This refers to the voltage at the end of the Y-phase line. δ is the valve-side voltage after adjustment by the phase-shifting transformer; δ' is the phase difference between the valve-side voltage of the Y-phase line transformer before phase adjustment and the voltage at the end of the line; δ′ is the phase difference between the valve-side voltage of the Y-phase line transformer and the voltage at both ends of the line after phase adjustment. The phase difference between the grid side and the valve side of the phase-shifting transformer in a Y-phase line. This refers to the equivalent reactance of the line between the valve side of the phase-shifting transformer and the end of the line. The equivalent impedance of a phase-shifting transformer in a Y-phase line.

[0015] The expression for the compensation voltage formula at each tap input terminal of the phase-shifting transformer is as follows:

[0016] (2)

[0017] (3)

[0018] (4)

[0019] (5)

[0020] In formula (2) These represent the voltage values ​​between each tap on the grid side of the Y-phase line transformer. This refers to the transformer grid-side voltage in a Y-phase line. This represents the change in phase angle between two adjacent taps. For a given phase angle value, The phase difference between the grid side and the valve side of the phase-shifting transformer in a Y-phase line. This refers to the number of taps on the grid side of the phase-shifting transformer.

[0021] In formula (3) This is the grid-side compensation voltage for the k-th transformer. This is the i-th term of the voltage between each tap on the transformer grid side, where i is any value between 0 and k.

[0022] In formula (4) This refers to the voltage between each tap on the transformer valve side in a Y-phase line. This refers to the voltage on the valve side of the phase-shifting transformer in the Y-phase line.

[0023] In formula (5) This is the compensation voltage on the valve side of the kth valve in the Y phase. This is the i-th term of the voltage between each tap on the transformer valve side, where i is any value between 0 and k.

[0024] The magnetic core is a three-branch iron core.

[0025] A control method for an independently and flexibly adjustable delta-hexagonal phase-shifting transformer, the control method comprising:

[0026] S1, calculate the initial phase difference. The phase-shifting transformer includes phase A, phase B, and phase C. Phase Y is any one of phases A, B, and C of the phase-shifting transformer. The voltage and phase of each phase valve side and line end of the phase-shifting transformer are measured in real time by a synchronous phasor measuring device, and the initial phase difference and initial amplitude difference of each phase are calculated according to equations (6) and (7):

[0027] (6)

[0028] In formula (6) The initial phase difference in the Y phase. This refers to the phase on the valve side of the phase-shifting transformer in the Y phase. This refers to the phase of the voltage at the end of the line in the Y phase.

[0029] S2, calculate the target phase difference. Obtain the target values ​​of the power transmitted in each phase of the phase-shifting transformer and the target values ​​of the line voltage from the upper-level management system, and calculate the target phase difference according to formula (7) based on the obtained target values:

[0030] (7)

[0031] In equation (7) δ ref P represents the target phase difference of the Y phase. ref This represents the target transmission power value for the Y phase. The resistance of the line between the output terminal of the Y-phase of the phase-shifting transformer and the end of the line is given. This refers to the equivalent reactance of the line between the output terminal of the Y-phase of the phase-shifting transformer and the end of the line. This represents the target value of the voltage on the valve side of the phase-shifting transformer in the Y phase. This refers to the voltage value on the valve side of the phase-shifting transformer in the Y phase. This refers to the voltage value at the end of the Y-phase line.

[0032] S3, calculate the required phase shift angle, and calculate the initial phase difference δ1 of each phase of the phase-shifting transformer obtained from the initial phase difference calculation in S1 and the target phase difference obtained from the target phase difference calculation in S2. Then, calculate the required phase shift angle of each phase according to equation (8):

[0033] (8)

[0034] In equation (8) The target phase difference of the Y phase of the phase-shifting transformer;

[0035] S4, calculate the voltage amplitude, and statistically analyze the line voltage target values ​​of each phase of the phase-shifting transformer calculated in S2 using the target phase difference. and the valve-side voltage after phase-shifting transformer adjustment And calculate the voltage amplitude of each phase according to equation (9):

[0036] (9)

[0037] In equation (9) This refers to the voltage amplitude difference of the Y phase of the phase-shifting transformer;

[0038] S5, define the control dead zone, and calculate the phase shift angle of the control dead zone of the phase-shifting transformer according to equation (11):

[0039] (10)

[0040] In formula (10) This refers to the dead zone phase shift angle of the Y phase of the phase-shifting transformer;

[0041] The control dead zone voltage of the phase-shifting transformer is calculated according to equation (11):

[0042] (11)

[0043] In formula (11) Dead zone voltage, The voltage values ​​between taps on the grid side of the phase-shifting transformer are given when... When outside the control dead zone, enter S6 to select the switching position. When the system is within the control dead zone, the control method is completed.

[0044] S6. Select the switching position. Choose the tap position that is close to the target phase shift angle of each phase of the phase-shifting transformer as the candidate switching position, and calculate the change in line voltage amplitude ΔU of all candidate switching positions. x Compare the changes ΔU at each candidate cutting position. x With voltage amplitude ΔU ref The difference is determined by selecting the candidate throwing position with the smallest difference as the throwing position.

[0045] S7, Detect error, calculate the phase shift angle error Δα and voltage amplitude error ΔU of each phase after adjustment. V When any of the following conditions occur in any phase of the phase-shifting transformer, all phases will return to S1 to calculate the initial phase difference:

[0046] a) Δα> ,

[0047] b) Δα≤ ΔU V > ;

[0048] If none of the above conditions occur, the currently selected candidate switching position is output to the execution system as the system switching position for the grid side and valve side of the three-phase circuit, and the control method is completed.

[0049] The phase-shifting transformer includes a logic processing module;

[0050] The logic processing module includes a processor and a memory;

[0051] The memory is used to store computer program code and to transmit the computer program code to the processor;

[0052] The processor is used to execute the control method of the independently adjustable delta-hexagonal phase-shifting transformer as described in claim 5 according to the instructions in the computer program code.

[0053] The processor obtains the target values ​​for transmission power and line voltage from the scheduling center.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0055] 1. In this invention, an independently adjustable delta-hexagonal phase-shifting transformer features three excitation windings and three voltage regulating windings connected in series alternately to form a ring structure. The excitation and voltage regulating windings intersect each other. The voltage regulating windings are connected to the excitation windings on both sides via two polarity switches, forming a symmetrical transformer structure. This symmetrical structure allows for independent adjustment of the taps on both sides of the phase-shifting transformer during adjustment, eliminating the need for symmetrical tap positions after adjustment. Therefore, this design allows for independent and flexible adjustment of the amplitude and phase of the line voltage, while maintaining high adjustment accuracy.

[0056] 2. In the independently adjustable delta-hexagonal phase-shifting transformer of this invention, because the taps on both sides of each phase of the phase-shifting transformer can be individually and asymmetrically adjusted, the phase and effective value of the line voltage can be independently and flexibly adjusted. This allows for relatively independent adjustment of the active and reactive power flow of the line, further optimizing the adjustment performance of the phase-shifting transformer. Therefore, this design can effectively improve the adjustment performance of the phase-shifting transformer by independently adjusting the active and reactive power flow of the line.

[0057] 3. In the independently adjustable delta-hexagonal phase-shifting transformer of this invention, the excitation winding and the voltage regulating winding are arranged on the three-branch core, so that the ampere-turns between each pair of core branches are equal, and the ampere-turns are not zero, thus improving the accuracy of circuit analysis. Therefore, this design can effectively improve the accuracy of circuit analysis by arranging each winding on the three-branch core.

[0058] 4. In the control method of the independently adjustable delta-hexagonal phase-shifting transformer of the present invention, the required phase shift angle is calculated by using the initial phase difference and the target phase difference. The switch position closest to the required phase shift angle, and whose phase shift angle error and voltage amplitude error do not exceed the limit value, is selected as the switch position. Therefore, this design can select a suitable switch position by the required phase shift angle, effectively improving the rationality of the switch position combination.

[0059] 5. In the control method of the independently adjustable delta-hexagonal phase-shifting transformer of the present invention, a control dead zone is set to allow for a suitable allowable error during adjustment of the phase-shifting transformer, preventing frequent switching between two positions. Therefore, this design can effectively reduce the switching frequency of the phase-shifting transformer by setting a suitable allowable error through a control dead zone. Attached Figure Description

[0060] Figure 1This is a topological diagram of the present invention.

[0061] Figure 2 This is a circuit diagram of the winding connection method of the present invention.

[0062] Figure 3 This is the voltage phase diagram of the present invention.

[0063] Figure 4 This is a schematic diagram of the voltage regulating winding in Example 1.

[0064] Figure 5 This is a schematic diagram of the power transmission line in Example 1.

[0065] Figure 6 This is a phase change diagram of the transformer grid-side voltage after the injection of compensation voltage in Example 1.

[0066] Figure 7 This is a schematic diagram of constant voltage phase shift adjustment in Example 1.

[0067] Figure 8 This is a schematic diagram of the boost phase shift adjustment in Example 1.

[0068] Figure 9 This is a schematic diagram of the voltage reduction phase shift adjustment in Example 1.

[0069] Figure 10 This is a schematic diagram of the reverse polarity phase shift adjustment in Example 1.

[0070] Figure 11 This is a block diagram of the control strategy for Embodiment 1.

[0071] Figure 12 This is a flowchart of the switching process of the control method of the present invention.

[0072] In the diagram: excitation winding 1, voltage regulating winding 2, on-load tap changer 21, polarity switch 22. Detailed Implementation

[0073] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0074] See Figures 1 to 9 A triangular-hexagonal phase-shifting transformer with independent and flexible adjustment, the phase-shifting transformer comprising: three excitation windings 1 and three voltage regulating windings 2;

[0075] The three excitation windings 1 are the three-phase windings of the phase-shifting transformer, and the three voltage regulating windings 2 are respectively set to correspond to the three excitation windings 1. The three excitation windings 1 and the three voltage regulating windings 2 are all set on the same magnetic core. The three excitation windings 1 and the three voltage regulating windings 2 are alternately connected end to end to form a triangular-hexagonal connection structure.

[0076] The three excitation windings 1 have the same structure, and the three voltage regulating windings 2 have the same structure. The voltage regulating winding 2 is provided with two on-load tap changers 21 and two polarity switches 22. One on-load tap changer 21 is on the grid side of the phase-shifting transformer, and the other on-load tap changer 21 is on the valve side of the phase-shifting transformer. The windings of the excitation winding 1 are divided into two parts, and each part of the excitation winding 1 is provided with an on-load tap changer 21. The voltage regulating winding 2 includes three polarity switch connection points. Two polarity switch connection points are the terminals on both sides of the voltage regulating winding 2, and the other polarity switch connection point is located in the middle of the voltage regulating winding 2. The polarity switch 22 includes an input pin and two output pins. The input pins of the two polarity switches 22 are respectively connected to the excitation winding 1 on their corresponding sides. One output pin of the two polarity switches 22 is simultaneously connected to the polarity switch connection point in the middle of the voltage regulating winding 2, and the other output pin of the two polarity switches 22 is respectively connected to both ends of the voltage regulating winding 2.

[0077] The phase-shifting transformer includes phase A, phase B, and phase C, and phase Y is any one of phases A, B, and C of the phase-shifting transformer. After the compensation voltage is injected through the phase-shifting transformer, the active power injected into phase Y of the phase-shifting transformer is... and reactive power The expression is:

[0078] (1)

[0079] In formula (1) This refers to the Y-phase grid-side voltage of the phase-shifting transformer. Inject compensation voltage from the Y-phase line into the phase-shifting transformer. This refers to the voltage at the end of the Y-phase line. δ is the valve-side voltage after adjustment by the phase-shifting transformer; δ' is the phase difference between the valve-side voltage of the Y-phase line transformer before phase adjustment and the voltage at the end of the line; δ′ is the phase difference between the valve-side voltage of the Y-phase line transformer and the voltage at both ends of the line after phase adjustment. The phase difference between the grid side and the valve side of the phase-shifting transformer in a Y-phase line. This refers to the equivalent reactance of the line between the valve side of the phase-shifting transformer and the end of the line. The equivalent impedance of a phase-shifting transformer in a Y-phase line.

[0080] The expression for the compensation voltage formula at each tap input terminal of the phase-shifting transformer is as follows:

[0081] (2)

[0082] (3)

[0083] (4)

[0084] (5)

[0085] In formula (2) These represent the voltage values ​​between each tap on the grid side of the Y-phase line transformer. This refers to the transformer grid-side voltage in a Y-phase line. This represents the change in phase angle between two adjacent taps. For a given phase angle value, The phase difference between the grid side and the valve side of the phase-shifting transformer in a Y-phase line. This refers to the number of taps on the grid side of the phase-shifting transformer.

[0086] In formula (3) This is the grid-side compensation voltage for the k-th transformer. This is the i-th term of the voltage between each tap on the transformer grid side, where i is any value between 0 and k.

[0087] In formula (4) This refers to the voltage between each tap on the transformer valve side in a Y-phase line. This refers to the voltage on the valve side of the phase-shifting transformer in the Y-phase line.

[0088] In formula (5) This is the compensation voltage on the valve side of the kth valve in the Y phase. This is the i-th term of the voltage between each tap on the transformer valve side, where i is any value between 0 and k.

[0089] The magnetic core is a three-branch iron core.

[0090] A control method for an independently and flexibly adjustable delta-hexagonal phase-shifting transformer, the control method comprising:

[0091] S1, calculate the initial phase difference. The phase-shifting transformer includes phase A, phase B, and phase C. Phase Y is any one of phases A, B, and C of the phase-shifting transformer. The voltage and phase of each phase valve side and line end of the phase-shifting transformer are measured in real time by a synchronous phasor measuring device, and the initial phase difference and initial amplitude difference of each phase are calculated according to equations (6) and (7):

[0092] (6)

[0093] In formula (6) The initial phase difference in the Y phase. This refers to the phase on the valve side of the phase-shifting transformer in the Y phase. This refers to the phase of the voltage at the end of the line in the Y phase.

[0094] S2, calculate the target phase difference. Obtain the target values ​​of the power transmitted in each phase of the phase-shifting transformer and the target values ​​of the line voltage from the upper-level management system, and calculate the target phase difference according to formula (7) based on the obtained target values:

[0095] (7)

[0096] In equation (7) δ ref P represents the target phase difference of the Y phase. ref This represents the target transmission power value for the Y phase. The resistance of the line between the output terminal of the Y-phase of the phase-shifting transformer and the end of the line is given. This refers to the equivalent reactance of the line between the output terminal of the Y-phase of the phase-shifting transformer and the end of the line. This represents the target value of the voltage on the valve side of the phase-shifting transformer in the Y phase. This refers to the voltage value on the valve side of the phase-shifting transformer in the Y phase. This refers to the voltage value at the end of the Y-phase line.

[0097] S3, calculate the required phase shift angle, and calculate the initial phase difference δ1 of each phase of the phase-shifting transformer obtained from the initial phase difference calculation in S1 and the target phase difference obtained from the target phase difference calculation in S2. Then, calculate the required phase shift angle of each phase according to equation (8):

[0098] (8)

[0099] In equation (8) The target phase difference of the Y phase of the phase-shifting transformer;

[0100] S4, calculate the voltage amplitude, and statistically analyze the line voltage target values ​​of each phase of the phase-shifting transformer calculated in S2 using the target phase difference. and the valve-side voltage after adjustment by the phase-shifting transformer And calculate the voltage amplitude of each phase according to equation (9):

[0101] (9)

[0102] In equation (9) This refers to the voltage amplitude difference of the Y phase of the phase-shifting transformer;

[0103] S5, define the control dead zone, and calculate the phase shift angle of the control dead zone of the phase-shifting transformer according to equation (11):

[0104] (10)

[0105] In formula (10) This refers to the dead zone phase shift angle of the Y phase of the phase-shifting transformer;

[0106] The control dead zone voltage of the phase-shifting transformer is calculated according to equation (11):

[0107] (11)

[0108] In formula (11) Dead zone voltage, The voltage values ​​between taps on the grid side of the phase-shifting transformer are given when... When outside the control dead zone, enter S6 to select the switching position. When the system is within the control dead zone, the control method is completed.

[0109] S6. Select the switching position. Choose the tap position that is close to the target phase shift angle of each phase of the phase-shifting transformer as the candidate switching position, and calculate the change in line voltage amplitude ΔU of all candidate switching positions. x Compare the changes ΔU at each candidate cutting position. x With voltage amplitude ΔU ref The difference is determined by selecting the candidate throwing position with the smallest difference as the throwing position.

[0110] S7, Detect error, calculate the phase shift angle error Δα and voltage amplitude error ΔU of each phase after adjustment. V When any of the following conditions occur in any phase of the phase-shifting transformer, all phases will return to S1 to calculate the initial phase difference:

[0111] a) Δα> ,

[0112] b) Δα≤ ΔU V > ;

[0113] If none of the above conditions occur, the currently selected candidate switching position is output to the execution system as the system switching position for the grid side and valve side of the three-phase circuit, and the control method is completed.

[0114] The phase-shifting transformer includes a logic processing module;

[0115] The logic processing module includes a processor and a memory;

[0116] The memory is used to store computer program code and to transmit the computer program code to the processor;

[0117] The processor is used to execute the control method of the independently adjustable delta-hexagonal phase-shifting transformer as described in claim 5 according to the instructions in the computer program code.

[0118] The processor obtains the target values ​​for transmission power and line voltage from the scheduling center.

[0119] The principle of this invention is explained as follows:

[0120] The basic electrical parameters of the phase-shifting transformer in this design are as follows:

[0121] The rated voltage U on the primary side of the phase-shifting transformer t1 for:

[0122] (12)

[0123] In equation (12) The rated voltage coefficient, U n This refers to the rated voltage level of the line.

[0124] The rated parameters of the secondary grid side and valve side voltage regulating winding 2 are the same, and the rated current I on the secondary grid side and valve side is the same. t2 With the maximum allowable current I of the line max equal;

[0125] The maximum phase shift angle of a single voltage regulating winding 2 is θ. Since the turns of voltage regulating winding 2 are divided into two parts, the maximum phase shift angle of any part is θ / 2. The maximum voltage on voltage regulating winding 2 is the maximum compensation voltage that can be injected into the line. The rated voltage of the voltage regulating winding is:

[0126] (13)

[0127] In equation (13) U t2 This is the rated voltage of the voltage regulating winding;

[0128] Rated capacity S n Equal to the sum of the capacities of the three voltage regulating windings on the secondary side (one voltage regulating winding in each phase of the line), the rated capacity S n for:

[0129] (14)

[0130] The rated current It1 on the primary side of the phase-shifting transformer is:

[0131] (15)

[0132] Example 1:

[0133] An independently adjustable delta-hexagonal phase-shifting transformer, the phase-shifting transformer comprising: three excitation windings 1 and three voltage regulating windings 2;

[0134] The three excitation windings 1 are the three-phase windings of the phase-shifting transformer, and the three voltage regulating windings 2 are respectively set to correspond to the three excitation windings 1. The three excitation windings 1 and the three voltage regulating windings 2 are all set on the same magnetic core. The three excitation windings 1 and the three voltage regulating windings 2 are alternately connected end to end to form a triangular-hexagonal connection structure.

[0135] The three excitation windings 1 have the same structure, and the three voltage regulating windings 2 have the same structure. The voltage regulating winding 2 is provided with two on-load tap changers 21 and two polarity switches 22. One on-load tap changer 21 is on the grid side of the phase-shifting transformer, and the other on-load tap changer 21 is on the valve side of the phase-shifting transformer. The windings of the excitation winding 1 are divided into two parts, and each part of the excitation winding 1 is provided with an on-load tap changer 21. The voltage regulating winding 2 includes three polarity switch connection points. Two polarity switch connection points are the terminals on both sides of the voltage regulating winding 2, and the other polarity switch connection point is located in the middle of the voltage regulating winding 2. The polarity switch 22 includes an input pin and two output pins. The input pins of the two polarity switches 22 are respectively connected to the excitation winding 1 on their corresponding sides. One output pin of the two polarity switches 22 is simultaneously connected to the polarity switch connection point in the middle of the voltage regulating winding 2, and the other output pin of the two polarity switches 22 is respectively connected to both ends of the voltage regulating winding 2.

[0136] The phase-shifting transformer includes phase A, phase B, and phase C, and phase Y is any one of phases A, B, and C of the phase-shifting transformer. After the compensation voltage is injected through the phase-shifting transformer, the active power injected into phase Y of the phase-shifting transformer is... and reactive power The expression is:

[0137] (1)

[0138] In formula (1) This refers to the Y-phase grid-side voltage of the phase-shifting transformer. Inject compensation voltage from the Y-phase line into the phase-shifting transformer. This is the voltage at the end of the Y-phase line. δ is the valve-side voltage after adjustment by the phase-shifting transformer; δ' is the phase difference between the valve-side voltage of the Y-phase line transformer before phase adjustment and the voltage at the end of the line; δ′ is the phase difference between the valve-side voltage of the Y-phase line transformer and the voltage at both ends of the line after phase adjustment. The phase difference between the grid side and the valve side of the phase-shifting transformer in a Y-phase line. This refers to the equivalent reactance of the line between the valve side of the phase-shifting transformer and the end of the line. The equivalent impedance of a phase-shifting transformer in a Y-phase line.

[0139] The expression for the compensation voltage formula at each tap input terminal of the phase-shifting transformer is as follows:

[0140] (2)

[0141] (3)

[0142] (4)

[0143] (5)

[0144] In formula (2) These represent the voltage values ​​between each tap on the grid side of the Y-phase line transformer. This refers to the transformer grid-side voltage in a Y-phase line. This represents the change in phase angle between two adjacent taps. For a given phase angle value, The phase difference between the grid side and the valve side of the phase-shifting transformer in a Y-phase line. The number of taps on the grid side of the phase-shifting transformer; in formula (3) This is the grid-side compensation voltage for the k-th transformer. The term is the i-th term of the voltage between each tap on the transformer grid side, where i is any value between 0 and k; in equation (4) This refers to the voltage between each tap on the transformer valve side in a Y-phase line. The voltage on the valve side of the phase-shifting transformer in the Y-phase line; in equation (5) This is the compensation voltage on the valve side of the kth valve in the Y phase. This is the i-th term of the voltage between each tap on the transformer valve side, where i is any value between 0 and k.

[0145] A control method for an independently and flexibly adjustable delta-hexagonal phase-shifting transformer, the control method comprising:

[0146] S1, calculate the initial phase difference. The phase-shifting transformer includes phase A, phase B, and phase C. Phase Y is any one of phases A, B, and C of the phase-shifting transformer. The voltage and phase of each phase valve side and line end of the phase-shifting transformer are measured in real time by a synchronous phasor measuring device, and the initial phase difference and initial amplitude difference of each phase are calculated according to equations (6) and (7):

[0147] (6)

[0148] In formula (6) The initial phase difference in the Y phase. This refers to the phase on the valve side of the phase-shifting transformer in the Y phase. This refers to the phase of the voltage at the end of the line in the Y phase.

[0149] S2, calculate the target phase difference. Obtain the target values ​​of the power transmitted in each phase of the phase-shifting transformer and the target values ​​of the line voltage from the upper-level management system, and calculate the target phase difference according to formula (7) based on the obtained target values:

[0150] (7)

[0151] In equation (7) δ ref P represents the target phase difference of the Y phase. ref This represents the target transmission power value for the Y phase. The resistance of the line between the output terminal of the Y-phase of the phase-shifting transformer and the end of the line is given. This refers to the equivalent reactance of the line between the output terminal of the Y-phase of the phase-shifting transformer and the end of the line. This represents the target value of the voltage on the valve side of the phase-shifting transformer in the Y phase. This refers to the voltage value on the valve side of the phase-shifting transformer in the Y phase. This refers to the voltage value at the end of the Y-phase line.

[0152] S3, calculate the required phase shift angle, and calculate the initial phase difference δ1 of each phase of the phase-shifting transformer obtained from the initial phase difference calculation in S1 and the target phase difference obtained from the target phase difference calculation in S2. Then, calculate the required phase shift angle of each phase according to equation (8):

[0153] (8)

[0154] In equation (8) The target phase difference of the Y phase of the phase-shifting transformer;

[0155] S4, calculate the voltage amplitude, and statistically analyze the line voltage target values ​​of each phase of the phase-shifting transformer calculated in S2 using the target phase difference. and the valve-side voltage after adjustment by the phase-shifting transformer And calculate the voltage amplitude of each phase according to equation (9):

[0156] (9)

[0157] In equation (9) This refers to the voltage amplitude difference of the Y phase of the phase-shifting transformer;

[0158] S5, define the control dead zone, and calculate the phase shift angle of the control dead zone of the phase-shifting transformer according to equation (11):

[0159] (10)

[0160] In formula (10) This refers to the dead zone phase shift angle of the Y phase of the phase-shifting transformer;

[0161] The control dead zone voltage of the phase-shifting transformer is calculated according to equation (11):

[0162] (11)

[0163] In formula (11) Dead zone voltage, The voltage values ​​between taps on the grid side of the phase-shifting transformer are given when... When outside the control dead zone, enter S6 to select the switching position. When the system is within the control dead zone, the control method is completed.

[0164] S6. Select the switching position. Choose the tap position that is close to the target phase shift angle of each phase of the phase-shifting transformer as the candidate switching position, and calculate the change in line voltage amplitude ΔU of all candidate switching positions. x Compare the changes ΔU at each candidate cutting position. x With voltage amplitude ΔU ref The difference is determined by selecting the candidate throwing position with the smallest difference as the throwing position.

[0165] S7, Detect error, calculate the phase shift angle error Δα and voltage amplitude error ΔU of each phase after adjustment. V When any of the following conditions occur in any phase of the phase-shifting transformer, all phases will return to S1 to calculate the initial phase difference:

[0166] a) Δα> ,

[0167] b) Δα≤ ΔU V > ;

[0168] If none of the above conditions occur, the currently selected candidate switching position is output to the execution system as the system switching position for the grid side and valve side of the three-phase circuit, and the control method is completed.

[0169] from Figure 6 As can be seen from the phase diagram, the transformer grid-side voltage in this phase line is... The compensation voltage of the DHPST injection line is superimposed. Then, the voltage on the valve side was obtained. Its phase angle change is α, which is related to the receiving voltage. The phase difference changes from δ to δ′. It is evident that the injection of DHPST compensation voltage alters the phase difference between the voltages at both ends of the line, thus achieving power flow control.

[0170] In this design, the compensation voltage of phase A in the phase-shifting transformer is the compensation voltage injected by the voltage regulating winding on the transformer grid side. Compensation voltage injected with the transformer valve-side regulating winding The sum of these values ​​indicates that the phase of phase A in the phase-shifting transformer is the grid-side adjustment phase. Adjusting the phase with the valve side The sum of the phase coefficients of phase A in a phase-shifting transformer is also equal to the sum of the winding coefficients at both ends. The product; when |k N | = |k V When |k|, the line voltage amplitude remains unchanged after phase shift; when |k| N | < |k V |The line voltage amplitude increases after the phase shift; and|k N | and |k V The greater the difference in voltage |k, the higher the line voltage amplitude; when |k N | > |k V When |kN| and |kV| are shifted, the line voltage amplitude decreases; and the greater the difference between |kN| and |kV|, the lower the line voltage amplitude.

[0171] The independent adjustment feature of this invention patent also lies in its ability to independently adjust the voltage phase and amplitude, maintain a constant voltage amplitude, and independently adjust the phase angle; Figure 7 In the middle, the voltage amplitude remains unchanged, only the phase angle changes. ; Figure 7 and Figure 8 In the middle, the changing phase remains unchanged. Change the voltage amplitude; as shown in the attached document. Figure 9 In addition, it can also be used for reverse polarity regulation.

[0172] Example 2:

[0173] Example 2 is basically the same as Example 1, except that:

[0174] The phase-shifting transformer includes a logic processing module; the logic processing module includes a processor and a memory; the memory is used to store computer program code and transmit the computer program code to the processor; the processor is used to execute a control method for an independently adjustable delta-hexagonal phase-shifting transformer according to the instructions in the computer program code.

[0175] Example 3:

[0176] Example 3 is basically the same as Example 2, except that:

[0177] The magnetic core is a three-branch iron core; the processor obtains the target value of transmission power and the target value of line voltage from the scheduling center.

[0178] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A triangular-hexagonal phase-shifting transformer with independent and flexible adjustment, characterized in that: The phase-shifting transformer includes: three excitation windings (1) and three voltage regulating windings (2); The three excitation windings (1) are the three-phase windings of the phase-shifting transformer, and the three voltage regulating windings (2) are respectively set to correspond to the three excitation windings (1). The three excitation windings (1) and the three voltage regulating windings (2) are all set on the same magnetic core. The three excitation windings (1) and the three voltage regulating windings (2) are connected end to end to form a triangular-hexagonal connection structure. The three excitation windings (1) have the same structure, and the three voltage regulating windings (2) have the same structure. Each voltage regulating winding (2) is equipped with two on-load tap changers (21) and two polarity switches (22). One on-load tap changer (21) is on the grid side of the phase-shifting transformer, and the other is on the valve side of the phase-shifting transformer. The windings of the excitation winding (1) are divided into two parts, and each part of the excitation winding (1) is equipped with an on-load tap changer (21). The voltage regulating winding (2) includes three polarity switch connection points. Two polarity switch connection points are the terminals on both sides of the voltage regulating winding (2), and another polarity switch connection point is located in the middle of the voltage regulating winding (2). The polarity switch (22) includes an input pin and two output pins. The input pins of the two polarity switches (22) are respectively connected to the excitation winding (1) on their corresponding sides. One of the output pins of the two polarity switches (22) is simultaneously connected to the polarity switch connection point in the middle of the voltage regulating winding (2), and the other output pin of the two polarity switches (22) is respectively connected to both ends of the voltage regulating winding (2).

2. The independently adjustable delta-hexagonal phase-shifting transformer according to claim 1, characterized in that: The phase-shifting transformer includes phase A, phase B, and phase C, and phase Y is any one of phases A, B, and C of the phase-shifting transformer. After the compensation voltage is injected through the phase-shifting transformer, the active power injected into phase Y of the phase-shifting transformer is... and reactive power The expression is: （1） In formula (1) This refers to the Y-phase grid-side voltage of the phase-shifting transformer. Inject compensation voltage from the Y-phase line into the phase-shifting transformer. This is the voltage at the end of the Y-phase line. δ is the valve-side voltage after adjustment by the phase-shifting transformer; δ' is the phase difference between the valve-side voltage of the Y-phase line transformer before phase adjustment and the voltage at the end of the line; δ′ is the phase difference between the valve-side voltage of the Y-phase line transformer and the voltage at both ends of the line after phase adjustment. The phase difference between the grid side and the valve side of the phase-shifting transformer in a Y-phase line. This refers to the equivalent reactance of the line between the valve side of the phase-shifting transformer and the end of the line. The equivalent impedance of a phase-shifting transformer in a Y-phase line.

3. The independently adjustable delta-hexagonal phase-shifting transformer according to claim 2, characterized in that: The expression for the compensation voltage formula at each tap input terminal of the phase-shifting transformer is as follows: （2） （3） （4） （5） In formula (2) These represent the voltage values ​​between each tap on the grid side of the Y-phase line transformer. This refers to the transformer grid-side voltage in a Y-phase line. This represents the change in phase angle between two adjacent taps. For a given phase angle value, The phase difference between the grid side and the valve side of the phase-shifting transformer in a Y-phase line. This refers to the number of taps on the grid side of the phase-shifting transformer. In formula (3) This is the grid-side compensation voltage for the k-th transformer. This is the i-th term of the voltage between each tap on the transformer grid side, where i is any value between 0 and k. In formula (4) This refers to the voltage between each tap on the transformer valve side in a Y-phase line. This refers to the voltage on the valve side of the phase-shifting transformer in the Y-phase line. In formula (5) This is the compensation voltage on the valve side of the kth valve in the Y phase. This is the i-th term of the voltage between each tap on the transformer valve side, where i is any value between 0 and k.

4. A triangular-hexagonal phase-shifting transformer with independent and flexible adjustment according to any one of claims 1, 2, or 3, characterized in that: The magnetic core is a three-branch iron core.

5. A control method for an independently adjustable delta-hexagonal phase-shifting transformer as described in any one of claims 1 to 4, characterized in that: The control method includes: S1, calculate the initial phase difference. The phase-shifting transformer includes phase A, phase B, and phase C. Phase Y is any one of phases A, B, and C of the phase-shifting transformer. The voltage and phase of each phase valve side and line end of the phase-shifting transformer are measured in real time by a synchronous phasor measuring device, and the initial phase difference and initial amplitude difference of each phase are calculated according to equations (6) and (7): （6） In formula (6) The initial phase difference in the Y phase. This refers to the phase on the valve side of the phase-shifting transformer in the Y phase. This refers to the phase of the voltage at the end of the line in the Y phase. S2, calculate the target phase difference. Obtain the target values ​​of the power transmitted in each phase of the phase-shifting transformer and the target values ​​of the line voltage from the upper-level management system, and calculate the target phase difference according to formula (7) based on the obtained target values: （7） In equation (7) δ ref P represents the target phase difference of the Y phase. ref This represents the target transmission power value for the Y phase. The resistance of the line between the output terminal of the Y-phase of the phase-shifting transformer and the end of the line is given. This refers to the equivalent reactance of the line between the output terminal of the Y-phase of the phase-shifting transformer and the end of the line. This represents the target value of the voltage on the valve side of the phase-shifting transformer in the Y phase. This refers to the voltage value on the valve side of the phase-shifting transformer in the Y phase. This refers to the voltage value at the end of the Y-phase line. S3, calculate the required phase shift angle, and calculate the initial phase difference δ1 of each phase of the phase-shifting transformer obtained from the initial phase difference calculation in S1 and the target phase difference obtained from the target phase difference calculation in S2. Then, calculate the required phase shift angle of each phase according to equation (8): （8） In equation (8) The target phase difference of the Y phase of the phase-shifting transformer; S4, calculate the voltage amplitude, and statistically analyze the line voltage target values ​​of each phase of the phase-shifting transformer calculated in S2 using the target phase difference. and the valve-side voltage after adjustment by the phase-shifting transformer And calculate the voltage amplitude of each phase according to equation (9): （9） In equation (9) This refers to the voltage amplitude difference of the Y phase of the phase-shifting transformer; S5, define the control dead zone, and calculate the phase shift angle of the control dead zone of the phase-shifting transformer according to equation (11): （10） In formula (10) This refers to the dead zone phase shift angle of the Y phase of the phase-shifting transformer; The control dead zone voltage of the phase-shifting transformer is calculated according to equation (11): （11） In formula (11) Dead zone voltage, The voltage values ​​between taps on the grid side of the phase-shifting transformer are given when... When outside the control dead zone, enter S6 to select the switching position. When the system is within the control dead zone, the control method is completed. S6. Select the switching position. Choose the tap position that is close to the target phase shift angle of each phase of the phase-shifting transformer as the candidate switching position, and calculate the change in line voltage amplitude ΔU of all candidate switching positions. x Compare the changes ΔU at each candidate cutting position. x With voltage amplitude ΔU ref The difference is determined by selecting the candidate throwing position with the smallest difference as the throwing position. S7, Detect error, calculate the phase shift angle error Δα and voltage amplitude error ΔU of each phase after adjustment. V When any of the following conditions occur in any phase of the phase-shifting transformer, all phases will return to S1 to calculate the initial phase difference: a) Yes> , b)Δα≤ ,ΔU V > ; If none of the above conditions occur, the currently selected candidate switching position is output to the execution system as the system switching position for the grid side and valve side of the three-phase circuit, and the control method is completed.

6. The control method for an independently and flexibly adjustable delta-hexagonal phase-shifting transformer according to claim 5, characterized in that: The phase-shifting transformer includes a logic processing module; The logic processing module includes a processor and a memory; The memory is used to store computer program code and to transmit the computer program code to the processor; The processor is used to execute the control method of the independently adjustable delta-hexagonal phase-shifting transformer as described in claim 5 according to the instructions in the computer program code.

7. The control method for an independently and flexibly adjustable delta-hexagonal phase-shifting transformer according to claim 6, characterized in that: The processor obtains the target values ​​for transmission power and line voltage from the scheduling center.

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