Intelligent monitoring method for short-circuit reactance of asymmetric three-phase distribution transformer

Abstract

This invention discloses an intelligent monitoring method for the short-circuit reactance of an asymmetrical three-phase distribution transformer. The method comprises the following steps: S1, setting the number of data acquisitions N and the interval T for the asymmetrical three-phase distribution transformer operating conditions; S2, cyclically acquiring the phase voltage and phase current of each phase of the three-phase distribution transformer under N different load conditions; S3, calculating the condition number corresponding to each combination of operating conditions for the N acquired operating conditions, obtaining the operating condition combination with the smallest condition number and the phase voltage and phase current of each phase of the three-phase distribution transformer under four different load conditions in that operating condition combination; S4, substituting the values ​​into the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Yyn0 connection or the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Dyn11 connection to obtain the short-circuit reactance value. The intelligent monitoring method provided by this invention is simple to implement, easy to implement, and can meet the requirements of power grids for safety, reliability, and economy.

Description

Technical Field

[0001] This invention belongs to the field of power system analysis technology, specifically a smart monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer. Background Technology

[0002] Transformers are indispensable key components in power grid operation, especially in the distribution sector where they hold an irreplaceable position. As a core element for the safe and stable operation of the power grid, the normal operating condition of distribution transformers plays a decisive role in the smooth operation of the entire power network and the quality of power supply. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the prior art by providing an intelligent monitoring method for the short-circuit reactance of an asymmetrical three-phase distribution transformer.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A smart monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer, comprising the following steps:

[0006] S1. Set the number of data collections N and the interval T for the unbalanced three-phase distribution transformer operating conditions;

[0007] S2. Cyclicly collect and obtain the phase voltage and phase current of each phase of the three-phase distribution transformer under N different load conditions;

[0008] S3. Calculate the N sets of working conditions collected. The condition number corresponding to each of the various operating condition combinations is used to obtain the operating condition combination with the smallest condition number, as well as the phase voltage and phase current of each phase of the three-phase distribution transformer under four different load conditions in that operating condition combination.

[0009] S4. Based on the connection method of the three-phase distribution transformer, input the data obtained in step S3 into the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Yyn0 connection method or the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Dyn11 connection method to obtain the short-circuit reactance value.

[0010] In step S1, the number of sampling times N is no less than 50 times and the interval time T is 0.2s.

[0011] The short-circuit reactance measurement model of the Yyn0 connection mode asymmetrical three-phase distribution transformer or the Dyn11 connection mode asymmetrical three-phase distribution transformer short-circuit reactance measurement model in step S4 is obtained based on the short-circuit reactance measurement model of the single-phase double-winding distribution transformer.

[0012] The method for measuring the short-circuit reactance of the single-phase double-winding distribution transformer is as follows: A model of the single-phase double-winding distribution transformer is constructed, wherein... These represent the voltage and current on the primary side of a single-phase, double-winding distribution transformer, respectively. These are the voltage and current on the secondary side of a single-phase, double-winding distribution transformer, respectively. These are the induced electromotive forces on the primary and secondary sides of a single-phase double-winding distribution transformer, respectively. These represent the number of turns on the primary and secondary windings of a single-phase double-winding distribution transformer, respectively. Based on relevant knowledge of single-phase double-winding distribution transformers and circuit theory, we can obtain:

[0013] (1)

[0014] (2)

[0015] In equations (1) and (2), This refers to the turns ratio of a single-phase, double-winding distribution transformer. These are the leakage impedances of the primary and secondary windings of a single-phase double-winding distribution transformer, respectively.

[0016] From equation (1), it can be seen that... If we consider the unknown quantity and the rest as known quantities, then equation (1) can be regarded as about... A linear equation in two variables is used to measure two sets of different loads. The unknown quantity can then be calculated. ,in , , and These represent the short-circuit resistance and short-circuit reactance of the winding, respectively.

[0017] In the Yyn0 / Dyn11 connection configuration, for a three-phase distribution transformer, the phase transformation ratio is the ratio of the induced electromotive force of the primary and secondary windings, or the ratio of the number of turns of the primary and secondary windings. That is:

[0018] (3)

[0019] In equation (3), Represents the primary winding of a three-phase distribution transformer. This represents the secondary winding of a three-phase distribution transformer.

[0020] In practical engineering applications, the three-phase turns ratios of a three-phase distribution transformer are all the same, that is:

[0021] (4).

[0022] The short-circuit reactance measurement model for the Yyn0 connection method asymmetrical three-phase distribution transformer in step S4 is established based on eliminating the neutral point voltage.

[0023] The method for constructing the short-circuit reactance measurement model of the Yyn0 connection asymmetrical three-phase distribution transformer in step S4 is as follows: In the circuit diagram of the three-phase distribution transformer with Yyn0 connection, This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the primary phase current of a three-phase distribution transformer. This refers to the induced electromotive force on the primary side of a three-phase distribution transformer. This refers to the neutral point voltage on the primary side of a three-phase distribution transformer. This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the secondary phase current of a three-phase distribution transformer. This refers to the induced electromotive force on the secondary side of a three-phase distribution transformer.

[0024] When the three-phase load on the secondary side of a three-phase distribution transformer is unbalanced, the neutral point voltage on the primary side will be... The value is not zero, resulting in neutral point displacement. Eliminating the neutral point voltage yields the short-circuit reactance measurement model for an asymmetrical three-phase distribution transformer with the Yyn0 connection method:

[0025] (5)

[0026] (6)

[0027] (7)

[0028] In equations (5), (6), and (7), The leakage impedance of the primary winding of a three-phase distribution transformer; The leakage impedance of the secondary winding of a three-phase distribution transformer;

[0029] In each of equations (5), (6), and (7), there are four unknowns. Therefore, by measuring the phase voltage and phase current of each phase of the three-phase distribution transformer under four different loads online, the short-circuit impedance of the three-phase windings can be solved.

[0030] (8)

[0031] The imaginary part of the short-circuit reactance of the three-phase winding is the corresponding short-circuit reactance of the three-phase winding:

[0032] (9)

[0033] Therefore, the short-circuit reactance of a three-phase distribution transformer is the average of the three values, i.e.:

[0034] (10).

[0035] The short-circuit reactance measurement model for the Dyn11 connection method asymmetrical three-phase distribution transformer in step S4 is based on eliminating circulating current. Establish.

[0036] The method for constructing the short-circuit reactance measurement model of the Dyn11-connected asymmetrical three-phase distribution transformer in step S4 is as follows:

[0037] In the circuit diagram of a three-phase distribution transformer with Dyn11 wiring configuration, This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the circulating current generated between the primary windings of a three-phase distribution transformer. This refers to the primary phase current of a three-phase distribution transformer. This refers to the primary line current of a three-phase distribution transformer. This refers to the induced electromotive force on the primary side of a three-phase distribution transformer. This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the secondary phase current of a three-phase distribution transformer. This refers to the induced electromotive force on the secondary side of a three-phase distribution transformer.

[0038] When the three-phase load on the secondary side of the distribution transformer is unbalanced, a circulating current will be generated between the delta-connected windings on the primary side of the distribution transformer. , will circulate Eliminating the faults yields the short-circuit reactance measurement model for an asymmetrical three-phase distribution transformer with Dyn11 wiring configuration:

[0039] (11)

[0040] (12)

[0041] (13)

[0042] In equations (11), (12), and (13), The leakage impedance of the primary winding of a three-phase distribution transformer; The leakage impedance of the secondary winding of a three-phase distribution transformer;

[0043] In each of equations (11), (12), and (13), there are four unknowns. Therefore, by measuring the phase voltage and phase current of each phase of the three-phase distribution transformer under four different loads online, the short-circuit impedance of the three-phase windings can be solved.

[0044] (9)

[0045] Therefore, the short-circuit reactance of the asymmetrical three-phase distribution transformer under the Dyn11 connection method can be obtained:

[0046] (10).

[0047] Step S3 requires constructing an asymmetrical three-phase distribution transformer short-circuit reactance data analysis model based on the Yyn0 connection asymmetrical three-phase distribution transformer short-circuit reactance measurement model or the Dyn11 connection asymmetrical three-phase distribution transformer short-circuit reactance measurement model in step S4. The method for constructing this asymmetrical three-phase distribution transformer short-circuit reactance data analysis model is as follows:

[0048] S31. Expand the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Yyn0 connection or the asymmetrical three-phase distribution transformer with Dyn11 connection based on the phase voltage and phase current of each phase of the three-phase distribution transformer under four different load conditions, and rewrite it as a set of matrix equations: ;

[0049] S32. The condition number of matrix A is as follows:

[0050] (19)

[0051] S33. For matrix equation systems Let the perturbations of the observations corresponding to matrices A and B be called... The equation obtained after the disturbance is:

[0052] (20)

[0053] S34. For equation (20), the following inequality exists:

[0054] (twenty one)

[0055] As shown in equation (21), the smaller the condition number of matrix A, the more accurate the result. Therefore, multiple measurements are needed to obtain the most suitable combination of working conditions to improve accuracy. Increasing the number of working conditions N will result in a larger number of equations than the number of unknowns, allowing the selection of the optimal working condition. After obtaining N sets of working conditions, the computer is used to calculate the results. The condition combination with the smallest condition number is selected from the combination of conditions corresponding to the various combinations.

[0056] The present invention has the following advantages over the prior art:

[0057] The intelligent monitoring method provided by this invention is based on a single-phase double-winding distribution transformer model to obtain a short-circuit reactance measurement model for a single-phase double-winding distribution transformer, and extends this method to an asymmetrical three-phase distribution transformer short-circuit reactance measurement model; it is simple and easy to implement, does not require the measurement of a large number of physical parameters, and can meet the requirements of power grid for safety, reliability and economy.

[0058] The intelligent monitoring method of the present invention simplifies the measurement process by eliminating the need to set complex coefficients when measuring the on-circuit reactance of an unbalanced three-phase distribution transformer.

[0059] The intelligent monitoring method of the present invention eliminates the need to measure the neutral point voltage when measuring the short-circuit reactance of a three-phase distribution transformer with an asymmetrical Yyn0 connection, thus reducing measurement errors.

[0060] The intelligent monitoring method of this invention eliminates the influence of circulating current on the measured value when measuring the short-circuit reactance of a three-phase distribution transformer with an asymmetrical Dyn11 wiring configuration.

[0061] The intelligent monitoring method of the present invention only requires measuring the phase voltage and phase current on the primary and secondary sides of the distribution transformer when calculating short-circuit reactance, which is easy to implement. Attached Figure Description

[0062] The intelligent monitoring method for short-circuit reactance of asymmetrical three-phase distribution transformers provided by the present invention will be further described below with reference to the accompanying drawings:

[0063] Appendix Figure 1 The single-phase dual-winding distribution transformer model used in the intelligent monitoring method for short-circuit reactance of asymmetrical three-phase distribution transformers provided by this invention;

[0064] Appendix Figure 2 Wiring diagram of a three-phase distribution transformer under the Yyn0 connection method used in the intelligent monitoring method for short-circuit reactance of asymmetrical three-phase distribution transformers provided by the present invention;

[0065] Appendix Figure 3 The wiring diagram of a three-phase distribution transformer under the Dyn11 wiring method used in the intelligent monitoring method for short-circuit reactance of asymmetrical three-phase distribution transformers provided by the present invention. Detailed Implementation

[0066] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that the invention will be thorough and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed description will be omitted.

[0067] The terms “a,” “one,” “the,” and “the” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended meaning of inclusion and that other elements / components / etc. may exist in addition to the listed elements / components / etc.

[0068] This invention provides an intelligent monitoring method for the short-circuit reactance of an asymmetrical three-phase distribution transformer. The method comprises the following steps:

[0069] S1. Set the number of data collections N and the interval T for the unbalanced three-phase distribution transformer operating conditions. The number of data collections N shall not be less than 50 and the interval T shall be 0.2s.

[0070] S2. Cyclicly collect and obtain the phase voltage and phase current of each phase of the three-phase distribution transformer under N different load conditions;

[0071] S3. Calculate the N sets of working conditions collected. The condition number corresponding to each of the various operating condition combinations is used to obtain the operating condition combination with the smallest condition number, as well as the phase voltage and phase current of each phase of the three-phase distribution transformer under four different load conditions in that operating condition combination.

[0072] S4. Based on the connection method of the three-phase distribution transformer, input the data obtained in step S3 into the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Yyn0 connection method or the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Dyn11 connection method to obtain the short-circuit reactance value.

[0073] In the intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer provided by this invention, both the Yyn0 connection asymmetrical three-phase distribution transformer short-circuit reactance measurement model and the Dyn11 connection asymmetrical three-phase distribution transformer short-circuit reactance measurement model are obtained based on the single-phase double-winding distribution transformer short-circuit reactance measurement model.

[0074] Single-phase dual-winding distribution transformer model as follows Figure 1 As shown, the method for measuring the short-circuit reactance of a single-phase, two-winding distribution transformer is as follows: Construct a model of a single-phase, two-winding distribution transformer, where... These represent the voltage and current on the primary side of a single-phase, double-winding distribution transformer, respectively. These are the voltage and current on the secondary side of a single-phase, double-winding distribution transformer, respectively. These are the induced electromotive forces on the primary and secondary sides of a single-phase double-winding distribution transformer, respectively. These represent the number of turns on the primary and secondary windings of a single-phase double-winding distribution transformer, respectively. Based on relevant knowledge of single-phase double-winding distribution transformers and circuit theory, we can obtain:

[0075] (1)

[0076] (2)

[0077] In equations (1) and (2), This refers to the turns ratio of a single-phase, double-winding distribution transformer. These are the leakage impedances of the primary and secondary windings of a single-phase double-winding distribution transformer, respectively.

[0078] From equation (1), it can be seen that... If we consider the unknown quantity and the rest as known quantities, then equation (1) can be regarded as about... A linear equation in two variables is used to measure two sets of different loads. The unknown quantity can then be calculated. ,in , , and These represent the short-circuit resistance and short-circuit reactance of the winding, respectively.

[0079] For three-phase distribution transformers, the most common wiring configurations are Yyn0 and Dyn11. The phase transformation ratio of a three-phase distribution transformer is the ratio of the induced electromotive force (EMF) of the primary and secondary windings, or the ratio of the number of turns of the primary and secondary windings. That is:

[0080] (3)

[0081] In equation (3), Represents the primary winding of a three-phase distribution transformer. This represents the secondary winding of a three-phase distribution transformer.

[0082] In practical engineering applications, the three-phase turns ratios of a three-phase distribution transformer are all the same, that is:

[0083] (4).

[0084] Based on the short-circuit reactance measurement model of a single-phase double-winding distribution transformer and the basic knowledge of three-phase distribution transformers, short-circuit reactance measurement models of asymmetrical three-phase distribution transformers with Yyn0 connection mode and Dyn11 connection mode are established.

[0085] The method for constructing the short-circuit reactance measurement model of the Yyn0-connected asymmetrical three-phase distribution transformer is as follows:

[0086] The circuit diagram of a three-phase distribution transformer with Yyn0 wiring is as follows: Figure 2 As shown, This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the primary phase current of a three-phase distribution transformer. This refers to the induced electromotive force on the primary side of a three-phase distribution transformer. This refers to the neutral point voltage on the primary side of a three-phase distribution transformer. This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the secondary phase current of a three-phase distribution transformer. This refers to the induced electromotive force on the secondary side of a three-phase distribution transformer.

[0087] When the three-phase load on the secondary side of a three-phase distribution transformer is unbalanced, the neutral point voltage on the primary side will be... The value is not zero, resulting in neutral point displacement. Eliminating the neutral point voltage yields the short-circuit reactance measurement model for an asymmetrical three-phase distribution transformer with the Yyn0 connection method:

[0088] (5)

[0089] (6)

[0090] (7)

[0091] In equations (5), (6), and (7), The leakage impedance of the primary winding of a three-phase distribution transformer; This refers to the leakage impedance of the secondary winding of a three-phase distribution transformer.

[0092] In each of equations (5), (6), and (7), there are four unknowns. Therefore, by measuring the phase voltage and phase current of each phase of the three-phase distribution transformer under four different loads online, the short-circuit impedance of the three-phase windings can be solved.

[0093] (8)

[0094] The imaginary part of the short-circuit reactance of the three-phase winding is the corresponding short-circuit reactance of the three-phase winding:

[0095] (9)

[0096] Therefore, the short-circuit reactance of a three-phase distribution transformer is the average of the three values, i.e.:

[0097] (10).

[0098] The method for constructing the short-circuit reactance measurement model of the Dyn11-connected asymmetrical three-phase distribution transformer is as follows:

[0099] The circuit diagram of a three-phase distribution transformer with Dyn11 wiring is as follows: Figure 3 As shown, This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the circulating current generated between the primary windings of a three-phase distribution transformer. This refers to the primary phase current of a three-phase distribution transformer. This refers to the primary line current of a three-phase distribution transformer. This refers to the induced electromotive force on the primary side of a three-phase distribution transformer. This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the secondary phase current of a three-phase distribution transformer. This refers to the induced electromotive force on the secondary side of a three-phase distribution transformer.

[0100] When the three-phase load on the secondary side of the distribution transformer is unbalanced, a circulating current will be generated between the delta-connected windings on the primary side of the distribution transformer. , will circulate Eliminating the faults yields the short-circuit reactance measurement model for an asymmetrical three-phase distribution transformer with Dyn11 wiring configuration:

[0101] (11)

[0102] (12)

[0103] (13)

[0104] In equations (11), (12), and (13), The leakage impedance of the primary winding of a three-phase distribution transformer; This refers to the leakage impedance of the secondary winding of a three-phase distribution transformer.

[0105] In each of equations (11), (12), and (13), there are four unknowns. Therefore, by measuring the phase voltage and phase current of each phase of the three-phase distribution transformer under four different loads online, the short-circuit impedance of the three-phase windings can be solved.

[0106] (9)

[0107] Therefore, the short-circuit reactance of the asymmetrical three-phase distribution transformer under the Dyn11 connection method can be obtained:

[0108] (10).

[0109] A data analysis model for the short-circuit reactance of an asymmetrical three-phase distribution transformer is established to reduce ill-conditioned errors and ensure the accuracy of the algorithm. Taking equations (5), (6), and (7) as examples, each of the above three equations has four unknowns. Therefore, it is only necessary to measure the phase voltage and phase current of each phase of the three-phase distribution transformer under four different loads online to solve for the short-circuit impedance value of the three-phase winding. Equation (5) can be expanded as follows:

[0110] (14)

[0111] In equation (14), , , Given the four sets of data that need to be measured, the above equation can be rewritten as a system of matrix equations:

[0112] (15)

[0113] in:

[0114] (16)

[0115] (17)

[0116] (18)

[0117] As can be seen from equations (15)-(18), due to measurement errors, the solution of the final equation system will deviate significantly when measuring the four sets of parameters. This is called an ill-conditioned equation system. Therefore, it is necessary to process the matrix equation system to ensure the accuracy of the algorithm.

[0118] The condition number of matrix A is as follows:

[0119] (19)

[0120] For matrix equations Let the perturbations of the observations corresponding to matrices A and B be called... The equation obtained after the disturbance is:

[0121] (20)

[0122] For equation (20), the following inequality exists:

[0123] (twenty one)

[0124] As shown in equation (21), the smaller the condition number of matrix A, the more accurate the result. Therefore, multiple measurements are needed to obtain the most suitable combination of working conditions to improve accuracy. Increasing the number of working conditions N will result in a larger number of equations than the number of unknowns, allowing the selection of the optimal working condition. After obtaining N sets of working conditions, the computer is used to calculate the results. The condition combination with the smallest condition number is selected from the combination of conditions corresponding to the various combinations.

[0125] The intelligent monitoring method provided by this invention is based on a single-phase double-winding distribution transformer model to obtain a short-circuit reactance measurement model for a single-phase double-winding distribution transformer, and extends this method to an asymmetrical three-phase distribution transformer short-circuit reactance measurement model; it is simple and easy to implement, does not require the measurement of a large number of physical parameters, and can meet the requirements of power grid for safety, reliability and economy.

[0126] In this embodiment of the invention, the term "multiple" refers to two or more, unless otherwise explicitly defined. The terms "install," "connect," and "fix" should be interpreted broadly. For example, "connect" can mean a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this embodiment of the invention based on the specific circumstances.

[0127] In the description of the embodiments of the present invention, it should be understood that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0128] In the description of this specification, the terms "an embodiment," "a preferred embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0129] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention. Technologies not covered in this invention can be implemented using existing technologies.

Claims

1. An intelligent monitoring method for the short-circuit reactance of an asymmetrical three-phase distribution transformer, characterized in that: The steps of this method are as follows: S1. Set the number of data collections N and the interval T for the unbalanced three-phase distribution transformer operating conditions; S2. Cyclicly collect and obtain the phase voltage and phase current of each phase of the three-phase distribution transformer under N different load conditions; S3. Calculate the N sets of working conditions collected. The condition number corresponding to each of the various operating condition combinations is used to obtain the operating condition combination with the smallest condition number, as well as the phase voltage and phase current of each phase of the three-phase distribution transformer under four different load conditions in that operating condition combination. S4. Based on the connection method of the three-phase distribution transformer, input the data obtained in step S3 into the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Yyn0 connection method or the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Dyn11 connection method to obtain the short-circuit reactance value.

2. The intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer according to claim 1, characterized in that: In step S1, the number of sampling times N is no less than 50 times and the interval time T is 0.2s.

3. The intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer according to claim 1, characterized in that: The short-circuit reactance measurement model of the Yyn0 connection mode asymmetrical three-phase distribution transformer or the Dyn11 connection mode asymmetrical three-phase distribution transformer short-circuit reactance measurement model in step S4 is obtained based on the short-circuit reactance measurement model of the single-phase double-winding distribution transformer.

4. The intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer according to claim 3, characterized in that: The method for measuring the short-circuit reactance of the single-phase double-winding distribution transformer is as follows: A model of the single-phase double-winding distribution transformer is constructed, wherein... These represent the voltage and current on the primary side of a single-phase, double-winding distribution transformer, respectively. These are the voltage and current on the secondary side of a single-phase, double-winding distribution transformer, respectively. These are the induced electromotive forces on the primary and secondary sides of a single-phase double-winding distribution transformer, respectively. These represent the number of turns on the primary and secondary windings of a single-phase double-winding distribution transformer, respectively. Based on relevant knowledge of single-phase double-winding distribution transformers and circuit theory, we can obtain: （1） （2） In equations (1) and (2), This refers to the turns ratio of a single-phase, double-winding distribution transformer. These are the leakage impedances of the primary and secondary windings of a single-phase double-winding distribution transformer, respectively. From equation (1), it can be seen that... If we consider the unknown quantity and the rest as known quantities, then equation (1) can be regarded as about... A linear equation in two variables is used to measure two sets of different loads. The unknown quantity can then be calculated. ,in , , and These represent the short-circuit resistance and short-circuit reactance of the winding, respectively.

5. The intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer according to claim 4, characterized in that: In the Yyn0 / Dyn11 connection configuration, for a three-phase distribution transformer, the phase transformation ratio is the ratio of the induced electromotive force of the primary and secondary windings, or the ratio of the number of turns of the primary and secondary windings. That is: （3） In equation (3), Represents the primary winding of a three-phase distribution transformer. This represents the secondary winding of a three-phase distribution transformer. In practical engineering applications, the three-phase turns ratios of a three-phase distribution transformer are all the same, that is: （4）。 6. The intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer according to claim 5, characterized in that: The short-circuit reactance measurement model for the Yyn0 connection method asymmetrical three-phase distribution transformer in step S4 is established based on eliminating the neutral point voltage.

7. The intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer according to claim 6, characterized in that: The method for constructing the short-circuit reactance measurement model of the Yyn0 connection asymmetrical three-phase distribution transformer in step S4 is as follows: In the circuit diagram of the Yyn0 connection three-phase distribution transformer, This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the primary phase current of a three-phase distribution transformer. This refers to the induced electromotive force on the primary side of a three-phase distribution transformer. This refers to the neutral point voltage on the primary side of a three-phase distribution transformer. This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the secondary phase current of a three-phase distribution transformer. This refers to the induced electromotive force on the secondary side of a three-phase distribution transformer. When the three-phase load on the secondary side of a three-phase distribution transformer is unbalanced, the neutral point voltage on the primary side will be... The value is not zero, resulting in neutral point displacement. Eliminating the neutral point voltage yields the short-circuit reactance measurement model for an asymmetrical three-phase distribution transformer with the Yyn0 connection method: （5） （6） （7） In equations (5), (6), and (7), The leakage impedance of the primary winding of a three-phase distribution transformer; The leakage impedance of the secondary winding of a three-phase distribution transformer; In each of equations (5), (6), and (7), there are four unknowns. Therefore, by measuring the phase voltage and phase current of each phase of the three-phase distribution transformer under four different loads online, the short-circuit impedance of the three-phase windings can be solved. （8） The imaginary part of the short-circuit reactance of the three-phase winding is the corresponding short-circuit reactance of the three-phase winding: （9） Therefore, the short-circuit reactance of a three-phase distribution transformer is the average of the three values, i.e.: （10）。 8. The intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer according to claim 5, characterized in that: The short-circuit reactance measurement model for the Dyn11 connection method asymmetrical three-phase distribution transformer in step S4 is based on eliminating circulating current. Establish.

9. The intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer according to claim 8, characterized in that: The method for constructing the short-circuit reactance measurement model of the Dyn11-connected asymmetrical three-phase distribution transformer in step S4 is as follows: In the circuit diagram of a three-phase distribution transformer with Dyn11 wiring configuration, This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the circulating current generated between the primary windings of a three-phase distribution transformer. This refers to the primary phase current of a three-phase distribution transformer. This refers to the primary line current of a three-phase distribution transformer. This refers to the induced electromotive force on the primary side of a three-phase distribution transformer. This refers to the primary phase voltage of a three-phase distribution transformer. This refers to the secondary phase current of a three-phase distribution transformer. This refers to the induced electromotive force on the secondary side of a three-phase distribution transformer. When the three-phase load on the secondary side of the distribution transformer is unbalanced, a circulating current will be generated between the delta-connected windings on the primary side of the distribution transformer. , will circulate Eliminating the faults yields the short-circuit reactance measurement model for an asymmetrical three-phase distribution transformer with Dyn11 wiring configuration: （11） （12） （13） In equations (11), (12), and (13), The leakage impedance of the primary winding of a three-phase distribution transformer; The leakage impedance of the secondary winding of a three-phase distribution transformer; In each of equations (11), (12), and (13), there are four unknowns. Therefore, by measuring the phase voltage and phase current of each phase of the three-phase distribution transformer under four different loads online, the short-circuit impedance of the three-phase windings can be solved. （9） Therefore, the short-circuit reactance of the asymmetrical three-phase distribution transformer under the Dyn11 connection method can be obtained: （10）。 10. The intelligent monitoring method for short-circuit reactance of an asymmetrical three-phase distribution transformer according to claim 1, characterized in that: Step S3 requires constructing an asymmetrical three-phase distribution transformer short-circuit reactance data analysis model based on the Yyn0 connection asymmetrical three-phase distribution transformer short-circuit reactance measurement model or the Dyn11 connection asymmetrical three-phase distribution transformer short-circuit reactance measurement model in step S4. The method for constructing this asymmetrical three-phase distribution transformer short-circuit reactance data analysis model is as follows: S31. Expand the short-circuit reactance measurement model of the asymmetrical three-phase distribution transformer with Yyn0 connection or the asymmetrical three-phase distribution transformer with Dyn11 connection based on the phase voltage and phase current of each phase of the three-phase distribution transformer under four different load conditions, and rewrite it as a set of matrix equations: ; S32. The condition number of matrix A is as follows: （19） S33. For matrix equation systems Let the perturbations of the observations corresponding to matrices A and B be called... The equation obtained after the disturbance is: （20） S34. For equation (20), the following inequality exists: （21） As shown in equation (21), the smaller the condition number of matrix A, the more accurate the result. Therefore, multiple measurements are needed to obtain the most suitable combination of working conditions to improve accuracy. Increasing the number of working conditions N will result in a larger number of equations than the number of unknowns, allowing the selection of the optimal working condition. After obtaining N sets of working conditions, the computer is used to calculate the results. The condition combination with the smallest condition number is selected from the combination of conditions corresponding to the various combinations.

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