Transformer short-circuit complex impedance synchronous vector measurement method and device

Abstract

The invention relates to the technical field of power systems, and discloses a transformer short-circuit complex impedance synchronous vector measurement method and device, and the method comprises the steps: employing a small-power single-phase power supply, applying a detection voltage to a neutral point of a measured winding, and synchronously collecting corresponding current vectors and voltage vectors in a short-circuit and open-circuit combined state of other windings; according to the corresponding current vector and the voltage vector, respectively obtaining each-phase first complex impedance and three-phase first total complex impedance of the high-voltage winding to the low-voltage winding, each-phase second complex impedance and three-phase second total complex impedance of the high-voltage winding to the middle and low-voltage windings, and each-phase third complex impedance and three-phase third total complex impedance of the middle-voltage winding to the low-voltage winding; and calculating complex impedance parameters of the transformer through the first complex impedance of each phase, the first total complex impedance of the three phases, the second complex impedance of each phase, the second total complex impedance of the three phases, the third complex impedance of each phase and the third total complex impedance of the three phases. The low-power single-phase power supply is used for pressurizing the neutral point to obtain the complex impedance, the wiring is simple, and the measurement precision is high.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and particularly to an AC power transformer, a method, a system, a storage medium, and a device for synchronously measuring the short-circuit complex impedance of a converter transformer. Background Art

[0002] The three-winding transformer is the main structural form of large main transformers in the power system and is widely operated in the power system. Before leaving the factory or being put into operation, the transformer should undergo a short-circuit impedance test and a short-circuit loss test to ensure that the design of the transformer meets the requirements of relevant regulations and performance requirements. However, the short-circuit impedance test and short-circuit loss test of the transformer require three-phase high-power voltage and related test equipment, and these tests are generally carried out at transformer manufacturing plants, transformer testing institutions, etc., and it is difficult to carry out on-site at the transformer operation site.

[0003] In the existing technology, the patent case with the patent application number CN202121621672.6 discloses a detection device for a transformer no-load loss, capacity, and short-circuit impedance tester. The device includes a microprocessor and multiple detection units connected thereto, and can realize the testing of transformer capacity, no-load short-circuit loss, and short-circuit impedance. However, this detection device is large in volume and high in cost, so it is difficult to carry out tests at the actual operation site of the transformer, which brings inconvenience to the on-site detection of the short-circuit parameters of the transformer.

[0004] To improve the test efficiency and test accuracy of the transformer, the present invention proposes a method and device for testing the short-circuit complex impedance of a transformer, which can use a small-power single-phase power supply to complete the measurement of the complex impedance parameters of each phase, the total complex impedance, the short-circuit loss, and the percentage of short-circuit voltage of a three-winding transformer. The complex-domain measurement method has higher measurement accuracy than the traditional short-circuit impedance test method, higher test efficiency, and more convenient on-site testing. It can compare measurement data horizontally and vertically, which is beneficial to accurately judging the state of the transformer winding. Summary of the Invention

[0005] Based on this, it is necessary to propose a method for synchronously measuring the short-circuit complex impedance of a transformer in view of the above problems.

[0006] A method for synchronously measuring the short-circuit complex impedance of a transformer, the method comprising:

[0007] Using a small-power single-phase power supply, applying a detection voltage to the neutral point of the winding under test, and synchronously collecting the corresponding current vector and voltage vector under the combined states of short-circuit and open-circuit of the remaining windings;

[0008] Obtain the first complex impedance of each phase of the high-voltage winding to the low-voltage winding, the first total complex impedance of three phases, the second complex impedance of each phase of the high-voltage winding to the medium and low-voltage windings, the second total complex impedance of three phases, and the third complex impedance of each phase of the medium-voltage winding to the low-voltage winding and the third total complex impedance of three phases according to the corresponding current vectors and voltage vectors respectively;

[0009] Calculate the complex impedance parameters of the transformer through the first complex impedance of each phase and the first total complex impedance of three phases, the second complex impedance of each phase and the second total complex impedance of three phases, and the third complex impedance of each phase and the third total complex impedance of three phases.

[0010] In the above solution, the use of a small-power single-phase power supply to apply a detection voltage at the neutral point of the measured winding, and in the combined state of short-circuiting and opening the remaining windings, synchronously collect the corresponding current vectors and voltage vectors, specifically including:

[0011] Short-circuit the three phases of the high-voltage winding of the transformer, open the medium-voltage winding and the low-voltage winding, apply a first detection voltage between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding, and synchronously collect the first three-phase current vector flowing into the transformer, the first neutral-point current vector, and the first voltage vector between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding;

[0012] Short-circuit the three phases of the high-voltage winding of the transformer, short-circuit the three phases of the medium-voltage winding and the neutral point of the medium-voltage winding, open the low-voltage winding, apply a second detection voltage between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding, and synchronously collect the second three-phase current vector flowing into the transformer, the second neutral-point current vector, and the second voltage vector between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding;

[0013] Short-circuit the three phases of the medium-voltage winding of the transformer, open the high-voltage winding and the low-voltage winding, apply a third detection voltage between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding, and synchronously collect the third three-phase current vector flowing into the transformer, the third neutral-point current vector, and the third voltage vector between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding;

[0014] Short-circuit the three phases of the medium-voltage winding of the transformer, short-circuit the three phases of the high-voltage winding and the neutral point of the high-voltage winding, open the low-voltage winding, apply a fourth detection voltage between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding, and synchronously collect the fourth three-phase current vector flowing into the transformer, the fourth neutral-point current vector, and the fourth voltage vector between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding.

[0015] In the above solution, determine the first complex impedance of each phase of the high-voltage winding to the low-voltage winding and the second complex impedance of each phase of the high-voltage winding to the medium and low-voltage windings according to the following formula:

[0016]

[0017] where \(i = 1, 2\); \(Z\) 1sp is the first complex impedance of the p-phase of the high-voltage winding with respect to the low-voltage winding; is the first voltage vector; is the first current vector of the p-phase; \(Z\) 2sp is the second complex impedance of the p-phase of the high-voltage winding with respect to the neutral and low-voltage windings; is the second voltage vector; is the second current vector of the p-phase;

[0018] Determine the third complex impedance of each phase of the medium-voltage winding with respect to the low-voltage winding and the fourth complex impedance of each phase of the medium-voltage winding with respect to the high-voltage and low-voltage windings according to the following formulas:

[0019]

[0020] where \(m = 3, 4\); \(Z\) 3sp is the third complex impedance of the p-phase of the medium-voltage winding with respect to the low-voltage winding reduced to the high-voltage winding; is the third voltage vector; is the third current vector of the p-phase; \(Z\) 4sp is the fourth complex impedance of the p-phase of the medium-voltage winding with respect to the high- and low-voltage windings reduced to the high-voltage winding; is the fourth voltage vector; is the fourth current vector of the p-phase; \(k\) 12 is the rated voltage ratio of the high-voltage winding to the medium-voltage winding.

[0021] In the above scheme, determine the three-phase first total complex impedance of the high-voltage winding with respect to the low-voltage winding and the three-phase second total complex impedance of the high-voltage winding with respect to the neutral and low-voltage windings according to the following formulas:

[0022]

[0023] where \(i = 1, 2\); \(Z\) 1a is the three-phase first total complex impedance of the high-voltage winding with respect to the low-voltage winding; is the first voltage vector; is the first neutral point current vector; \(Z\) 2a is the three-phase second total complex impedance of the high-voltage winding with respect to the neutral and low-voltage windings; is the second voltage vector; is the second neutral point current vector;

[0024] Determine the three-phase third total complex impedance of the medium-voltage winding with respect to the low-voltage winding and the three-phase fourth total complex impedance of the medium-voltage winding with respect to the high-voltage winding according to the following formulas:

[0025]

[0026] where \(m = 3, 4\); \(Z\) 3ais the three-phase third total complex impedance of the medium-voltage winding with respect to the low-voltage winding; is the third voltage vector; is the third neutral point current vector; k 12 is the rated voltage ratio of the high-voltage winding to the medium-voltage winding; Z 4a is the three-phase fourth total complex impedance of the medium-voltage winding with respect to the high- and low-voltage windings; is the fourth voltage vector; is the fourth neutral point current vector.

[0027] In the above solution, by means of the first complex impedance of each phase, the second complex impedance of each phase, the third complex impedance of each phase, and the fourth complex impedance of each phase, the complex impedance parameters of each phase of each winding reduced to the high-voltage winding are calculated, including:

[0028] For phase p, write the first complex impedance equation of phase p: Z 1sp = Z Ip + Z IIIp ;

[0029] Write the second complex impedance equation of phase p:

[0030] Write the third complex impedance equation of phase p: Z 3sp = Z IIp + Z IIIp ;

[0031] Write the fourth complex impedance equation of phase p:

[0032] Arbitrarily select three equations from the first complex impedance equation of phase p, the second complex impedance equation of phase p, the third complex impedance equation of phase p, and the fourth complex impedance equation of phase p to form a first system of equations;

[0033] Solve the first system of equations to obtain the complex impedance parameters of phase p of each winding;

[0034] Among them, Z 1sp is the first complex impedance of phase p; Z 2sp is the second complex impedance of phase p; Z 3sp is the third complex impedance of phase p; Z 4sp is the fourth complex impedance of phase p; Z Ip is the complex impedance of phase p of the high-voltage winding; Z IIp is the complex impedance of phase p of the medium-voltage winding; Z IIIp is the complex impedance of phase p of the low-voltage winding.

[0035] In the above solution, by means of the three-phase first total complex impedance, the three-phase second total complex impedance, the three-phase third total complex impedance, and the three-phase fourth total complex impedance, the complex impedance parameters of each winding reduced to the high-voltage winding are calculated, including:

[0036] Write the first total complex impedance equation: Z 1a = Z I + Z III ;

[0037] Write the second total complex impedance equation:

[0038] Write the third total complex impedance equation: Z 3a = Z II + Z III ;

[0039] Write the fourth total complex impedance equation:

[0040] Arbitrarily select three equations from the first total complex impedance equation, the second total complex impedance equation, the third total complex impedance equation, and the fourth total complex impedance equation to form a second system of equations;

[0041] Solve the second system of equations to obtain the complex impedances of each winding;

[0042] Among them, Z 1a is the three-phase first total complex impedance; Z 2a is the three-phase first total complex impedance; Z 3a is the three-phase first total complex impedance; Z 4a is the three-phase first total complex impedance; Z I is the high-voltage winding complex impedance; Z II is the complex impedance of the medium-voltage winding referred to the high-voltage winding; Z III is the complex impedance of the low-voltage winding referred to the high-voltage winding.

[0043] In the above solution, after calculating the complex impedance parameters of the transformer, the method further includes calculating the short-circuit loss and short-circuit voltage percentage of the transformer:

[0044] Calculate the total complex impedance between each winding of the transformer;

[0045] Determine the short-circuit loss and short-circuit voltage percentage of the transformer according to the total complex impedance between each winding. In the above solution, the calculation of the total complex impedance between each winding of the transformer specifically includes:

[0046] Determine the complex impedance Z 12 or Z 21 between the high-voltage winding and the medium-voltage winding of the transformer, the complex impedance Z 13 or Z 31 between the high-voltage winding and the low-voltage winding of the transformer, and the complex impedance Z 23 or Z 32 of the medium-voltage winding to the low-voltage winding referred to the high-voltage winding according to the following formula:

[0047] Z in =Z ni =Z i +Z n

[0048] where i = 1, 2; n = 2, 3; Z 12 and Z 21 is the complex impedance between the high-voltage winding and the medium-voltage winding of the transformer; Z Ⅰ is the complex impedance of the high-voltage winding; Z Ⅱ is the complex impedance of the medium-voltage winding referred to the high-voltage winding; Z 13 and Z 31 is the complex impedance between the high-voltage winding and the low-voltage winding of the transformer; Z Ⅰ is the complex impedance of the high-voltage winding; Z 23 and Z 32 is the complex impedance between the medium-voltage winding and the low-voltage winding of the transformer; Z Ⅱ is the complex impedance of the medium-voltage winding referred to the high-voltage winding; Z Ⅲ is the complex impedance of the low-voltage winding referred to the high-voltage winding.

[0049] In the above solution, determining the short-circuit loss and short-circuit voltage percentage of the transformer according to the total complex impedance between the windings specifically includes:

[0050] Determining the short-circuit loss and short-circuit voltage percentage between the windings of the transformer according to the following formula:

[0051]

[0052] where P fj is the short-circuit loss between the f-th winding and the j-th winding; U fj is the short-circuit voltage percentage between the f-th winding and the j-th winding; Zf j is the total complex impedance between the f-th winding and the j-th winding; when f, j = 1, it is the high-voltage winding; when f, j = 2, it is the medium-voltage winding; when f, j = 3, it is the low-voltage winding; S N is the transformer capacity; the unit is kVA; U N is the rated voltage of the high-voltage winding of the transformer; real() is the real part function; imag() is the imaginary part function; f, j = 1, 2, 3 and f ≠ j.

[0053] This application also proposes a transformer short-circuit complex impedance measuring device, including:

[0054] A single-phase power frequency power supply for providing a stable power frequency detection voltage to the winding under test;

[0055] A detection unit, configured to synchronously collect corresponding current vectors and voltage vectors when the remaining windings are in a short-circuit and open-circuit combined state;

[0056] An impedance calculation unit, configured to receive the current vector and voltage vector data from the detection unit, and respectively calculate the first complex impedance of each phase and the first total complex impedance of three phases, the second complex impedance of each phase and the second total complex impedance of three phases, the third complex impedance of each phase and the third total complex impedance of three phases, and the fourth complex impedance of each phase and the fourth total complex impedance of three phases;

[0057] A test parameter calculation unit, configured to calculate and output the complex impedance parameters of the transformer according to the complex impedance of each phase and the total complex impedance of three phases calculated by the impedance calculation unit.

[0058] By applying a detection voltage to the neutral point of the winding under test using a small-power single-phase power supply, the present invention effectively reduces the energy consumption and equipment burden during the detection process. When the remaining windings are in a short-circuit and open-circuit combined state, the corresponding current vectors and voltage vectors are synchronously collected to ensure the consistency and accuracy of the data. Then, according to the collected current vectors and voltage vectors, the complex impedance of each phase and the total complex impedance between the high-voltage winding and the low-voltage winding, between the high-voltage winding and the medium- and low-voltage windings, and between the medium-voltage winding and the low-voltage winding are respectively calculated. Finally, the complex impedance parameters of the transformer are calculated by synthesizing the complex impedance of each phase and the total complex impedance. The present invention only uses a small-power single-phase power supply to complete the measurement of the short-circuit impedance and short-circuit loss of the transformer, reduces the cost of parameter measurement, and enables the on-site performance evaluation of the transformer to be more convenient and efficient. Brief Description of the Drawings

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0060] Among them,

[0061] Figure 1 It is a schematic flowchart of a method for synchronously measuring the short-circuit complex impedance of a transformer in an embodiment;

[0062] Figure 2 It is a schematic diagram of the implementation process of a method for synchronously measuring the short-circuit complex impedance of a transformer;

[0063] Figure 3 It is a second schematic diagram of the implementation process of a method for synchronously measuring the short-circuit complex impedance of a transformer;

[0064] Figure 4It is the third schematic diagram of the implementation process of a synchronous vector measurement method for the short-circuit complex impedance of a transformer;

[0065] Figure 5 It is the fourth schematic diagram of the implementation process of a synchronous vector measurement method for the short-circuit complex impedance of a transformer;

[0066] Figure 6 It is a schematic diagram of a device for measuring the short-circuit complex impedance of a transformer. Specific implementation manner

[0067] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0068] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of the present invention. When used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, determine the presence of the described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. When used herein, the term "and / or" includes any and all combinations of the related listed items.

[0069] As Figure 1 shown, in one embodiment, a synchronous vector measurement method for the short-circuit complex impedance of a transformer is provided. This synchronous vector measurement method for the short-circuit complex impedance of a transformer includes steps S101 to S103, which are described in detail as follows:

[0070] S101. Use a small-power single-phase power supply to apply a detection voltage to the neutral point of the measured winding. Under the combined states of short-circuit and open-circuit of the remaining windings, synchronously collect the corresponding current vectors and voltage vectors;

[0071] The use of a small-power single-phase power supply in the present invention not only reduces energy consumption and equipment costs, but also reduces safety risks during the measurement process. Applying a detection voltage to the neutral point of the measured winding can accurately control the measurement conditions and ensure the accuracy of the data. The combined states of short-circuit and open-circuit of the remaining windings simulate various fault conditions that may occur in actual operation, making the measurement results more practical. Synchronously collecting current and voltage vectors ensures the consistency of the data and provides a reliable basis for subsequent calculations.

[0072] In some embodiments, a low-power single-phase power supply is used to apply a detection voltage to the neutral point of the winding under test. When the remaining windings are in a combined state of short circuit and open circuit, the corresponding current vectors and voltage vectors are synchronously collected, specifically including:

[0073] Short-circuit the three phases of the high-voltage winding of the transformer, and open the medium-voltage winding and the low-voltage winding. Apply a first detection voltage between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding, and synchronously collect the first three-phase current vector flowing into the transformer, the first neutral-point current vector, and the first voltage vector between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding;

[0074] Short-circuit the three phases of the high-voltage winding of the transformer, short-circuit the three phases and the neutral point of the medium-voltage winding, and open the low-voltage winding. Apply a second detection voltage between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding, and synchronously collect the second three-phase current vector flowing into the transformer, the second neutral-point current vector, and the second voltage vector between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding;

[0075] Short-circuit the three phases of the medium-voltage winding of the transformer, and open the high-voltage winding and the low-voltage winding. Apply a third detection voltage between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding, and synchronously collect the third three-phase current vector flowing into the transformer, the third neutral-point current vector, and the third voltage vector between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding;

[0076] Short-circuit the three phases of the medium-voltage winding of the transformer, short-circuit the three phases and the neutral point of the high-voltage winding, and open the low-voltage winding. Apply a fourth detection voltage between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding, and synchronously collect the fourth three-phase current vector flowing into the transformer, the fourth neutral-point current vector, and the fourth voltage vector between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding.

[0077] S102. Respectively obtain the first complex impedance of each phase and the first total complex impedance of three phases of the high-voltage winding to the low-voltage winding, the second complex impedance of each phase and the second total complex impedance of three phases of the high-voltage winding to the medium- and low-voltage windings, and the third complex impedance of each phase and the third total complex impedance of three phases of the medium-voltage winding to the low-voltage winding according to the corresponding current vectors and voltage vectors;

[0078] By calculating the complex impedance of each phase and the total complex impedance under different winding combinations respectively, the short-circuit impedance characteristics of the transformer under different working conditions are comprehensively revealed. These detailed impedance parameters provide important data support for in-depth analysis of the electrical performance, design optimization, and fault diagnosis of the transformer.

[0079] In some embodiments, the first complex impedance of each phase of the high-voltage winding to the low-voltage winding and the second complex impedance of each phase of the high-voltage winding to the medium- and low-voltage windings are determined according to the following formula:

[0080]

[0081] where \(i = 1, 2\); \(Z\) 1sp is the first complex impedance of the p-phase of the high-voltage winding with respect to the low-voltage winding; is the first voltage vector; is the first current vector of the p-phase; \(Z\) 2sp is the second complex impedance of the p-phase of the high-voltage winding with respect to the medium-voltage and low-voltage windings; is the second voltage vector; is the second current vector of the p-phase;

[0082] The third complex impedance of each phase of the medium-voltage winding with respect to the low-voltage winding and the fourth complex impedance of each phase of the medium-voltage winding with respect to the high-voltage and low-voltage windings are determined according to the following formulas:

[0083]

[0084] where \(m = 3, 4\); \(Z\) 3sp is the third complex impedance of the p-phase of the medium-voltage winding with respect to the low-voltage winding reduced to the high-voltage winding; is the third voltage vector; is the third current vector of the p-phase; \(Z\) 4sp is the fourth complex impedance of the p-phase of the medium-voltage winding with respect to the high- and low-voltage windings reduced to the high-voltage winding; is the fourth voltage vector; is the fourth current vector of the p-phase; \(k\) 12 is the rated voltage ratio between the high-voltage winding and the medium-voltage winding.

[0085] In some embodiments, the three-phase first total complex impedance of the high-voltage winding with respect to the low-voltage winding and the three-phase second total complex impedance of the high-voltage winding with respect to the medium-voltage and low-voltage windings are determined according to the following formulas:

[0086]

[0087] where \(i = 1, 2\); \(Z\) 1a is the three-phase first total complex impedance of the high-voltage winding with respect to the low-voltage winding; is the first voltage vector; is the first neutral point current vector; \(Z\) 2a is the three-phase second total complex impedance of the high-voltage winding with respect to the medium-voltage and low-voltage windings; is the second voltage vector; is the second neutral point current vector;

[0088] The three-phase third total complex impedance of the medium-voltage winding with respect to the low-voltage winding and the three-phase fourth total complex impedance of the medium-voltage winding with respect to the high-voltage winding are determined according to the following formulas:

[0089]

[0090] where \(m = 3, 4\); \(Z\) 3ais the three-phase third total complex impedance of the medium-voltage winding with respect to the low-voltage winding; is the third voltage vector; is the third neutral point current vector; k 12 is the rated voltage ratio of the high-voltage winding to the medium-voltage winding; Z 4a is the three-phase fourth total complex impedance of the medium-voltage winding with respect to the high- and low-voltage windings; is the fourth voltage vector; is the fourth neutral point current vector.

[0091] In some embodiments, by means of the first complex impedance of each phase, the second complex impedance of each phase, the third complex impedance of each phase, and the fourth complex impedance of each phase, the complex impedance parameters of each winding of each phase reduced to the high-voltage winding are calculated, including:

[0092] For phase p, write the first complex impedance equation for phase p: Z 1sp =Z Ip +Z IIIp ;

[0093] Write the second complex impedance equation for phase p:

[0094] Write the third complex impedance equation for phase p: Z 3sp =Z IIp +Z IIIp ;

[0095] Write the fourth complex impedance equation for phase p:

[0096] Arbitrarily select three equations from the first complex impedance equation for phase p, the second complex impedance equation for phase p, the third complex impedance equation for phase p, and the fourth complex impedance equation for phase p to form the first system of equations;

[0097] Solve the first system of equations to obtain the complex impedance parameters of each winding of phase p;

[0098] Among them, Z 1sp is the first complex impedance of phase p; Z 2sp is the second complex impedance of phase p; Z 3sp is the third complex impedance of phase p; Z 4sp is the fourth complex impedance of phase p; Z Ip is the complex impedance of phase p of the high-voltage winding; Z IIp is the complex impedance of phase p of the medium-voltage winding; Z IIIp is the complex impedance of phase p of the low-voltage winding.

[0099] In some embodiments, by means of the three-phase first total complex impedance, the three-phase second total complex impedance, the three-phase third total complex impedance, and the three-phase fourth total complex impedance, the complex impedance parameters of each winding reduced to the high-voltage winding are calculated, including:

[0100] Write the first total complex impedance equation: Z 1a = Z I + Z III ;

[0101] Write the second total complex impedance equation:

[0102] Write the third total complex impedance equation: Z 3a = Z II + Z III ;

[0103] Write the fourth total complex impedance equation:

[0104] Arbitrarily select three equations from the first total complex impedance equation, the second total complex impedance equation, the third total complex impedance equation, and the fourth total complex impedance equation to form a second set of equations;

[0105] Solve the second set of equations to obtain the complex impedances of each winding;

[0106] Among them, Z 1a is the three-phase first total complex impedance; Z 2a is the three-phase first total complex impedance; Z 3a is the three-phase first total complex impedance; Z 4a is the three-phase first total complex impedance; Z I is the complex impedance of the high-voltage winding; Z II is the complex impedance of the medium-voltage winding reduced to the high-voltage winding; Z III is the complex impedance of the low-voltage winding reduced to the high-voltage winding.

[0107] Specifically, take the first total complex impedance equation, the second total complex impedance equation, and the third total complex impedance equation to form a set of equations, and its corresponding solutions are:

[0108]

[0109] Among them, Z 1a is the three-phase first total complex impedance; Z 2a is the three-phase first total complex impedance; Z 3a is the three-phase first total complex impedance; Z I is the complex impedance of the high-voltage winding; Z II is the complex impedance of the medium-voltage winding reduced to the high-voltage winding; Z III is the complex impedance of the low-voltage winding reduced to the high-voltage winding.

[0110] Take the first total complex impedance equation, the second total complex impedance equation, and the fourth total complex impedance equation to form a set of equations, and its corresponding solutions are:

[0111]

[0112] Take the first total complex impedance equation, the third total complex impedance equation, and the fourth total complex impedance equation to form a system of equations, and its corresponding solutions are:

[0113]

[0114] Among them, Z 1a is the three-phase first total complex impedance; Z 3a is the three-phase first total complex impedance; Z 4a is the three-phase first total complex impedance; Z I is the complex impedance of the high-voltage winding; Z II is the complex impedance of the medium-voltage winding reduced to the high-voltage winding; Z III is the complex impedance of the low-voltage winding reduced to the high-voltage winding.

[0115] Take the second total complex impedance equation, the third total complex impedance equation, and the fourth total complex impedance equation to form a system of equations, and its corresponding solutions are:

[0116]

[0117] Among them, Z 2a is the three-phase first total complex impedance; Z 3a is the three-phase first total complex impedance; Z 4a is the three-phase first total complex impedance; Z I is the complex impedance of the high-voltage winding; Z II is the complex impedance of the medium-voltage winding reduced to the high-voltage winding; Z III is the complex impedance of the low-voltage winding reduced to the high-voltage winding.

[0118] It can be seen that by writing and solving four total complex impedance equations, the short-circuit impedance characteristics of the transformer under different winding combinations are covered, ensuring the comprehensiveness and no omission of parameter calculation. Then, by arbitrarily taking three equations to form a system of equations for solution, the complex impedance parameters of each winding are obtained. This method of solving multiple systems of equations effectively eliminates the errors that may be brought by a single equation and improves the accuracy of the parameters. At the same time, multiple combinations of systems of equations are provided, such as the first, second, and third total complex impedance systems of equations, or the first, second, and fourth total complex impedance systems of equations, etc. This flexibility enables the calculation to adapt to different measurement conditions and requirements. It realizes fast and efficient parameter calculation and greatly shortens the time for measuring the short-circuit complex impedance of the transformer.

[0119] S103. Calculate the complex impedance parameters of the transformer through the first complex impedance of each phase and the three-phase first total complex impedance, the second complex impedance of each phase and the three-phase second total complex impedance, and the third complex impedance of each phase and the three-phase third total complex impedance.

[0120] Based on the combined complex impedance parameters of each phase and the total complex impedance parameters, the overall complex impedance parameters of the transformer are calculated, which directly reflect the short-circuit performance of the transformer. Accurate complex impedance parameters are of great significance for the operation and maintenance, fault prevention, energy efficiency evaluation, and design improvement of the transformer. The entire measurement and calculation process is efficient and accurate, improving the technical level of the short-circuit complex impedance measurement of the transformer and providing a strong guarantee for the stable operation of the power system and the safety of equipment.

[0121] In some embodiments, after calculating the complex impedance parameters of the transformer, the method further includes calculating the short-circuit loss and the percentage of short-circuit voltage of the transformer:

[0122] Calculate the total complex impedance between each winding of the transformer;

[0123] Determine the short-circuit loss and the percentage of short-circuit voltage of the transformer according to the total complex impedance between each winding.

[0124] In some embodiments, calculating the total complex impedance between each winding of the transformer specifically includes:

[0125] Determine the complex impedance Z between the high-voltage winding and the medium-voltage winding of the transformer according to the following formula 12 or Z 21 , the complex impedance Z between the high-voltage winding and the low-voltage winding of the transformer 13 or Z 31 and the complex impedance Z of the medium-voltage winding to the low-voltage winding reduced to the high-voltage winding of the transformer 23 or Z 32 :

[0126] Z in =Z ni =Z i +Z n

[0127] where i = 1, 2; n = 2, 3; Z 12 , Z 21 is the complex impedance between the high-voltage winding and the medium-voltage winding of the transformer; Z Ⅰ is the complex impedance of the high-voltage winding; Z Ⅱ is the complex impedance of the medium-voltage winding reduced to the high-voltage winding; Z 13 , Z 31 is the complex impedance between the high-voltage winding and the low-voltage winding of the transformer; Z Ⅰ is the complex impedance of the high-voltage winding; Z 23 , Z 32 is the complex impedance between the medium-voltage winding and the low-voltage winding of the transformer; Z Ⅱ is the complex impedance of the medium-voltage winding reduced to the high-voltage winding; Z Ⅲ is the complex impedance of the low-voltage winding reduced to the high-voltage winding.

[0128] In some embodiments, the short-circuit loss and the percentage of short-circuit voltage of the transformer are determined according to the total complex impedance between windings, specifically including:

[0129] Determine the short-circuit loss and the percentage of short-circuit voltage between each winding of the transformer according to the following formula:

[0130]

[0131] where P fj is the short-circuit loss between the f-th winding and the j-th winding; U fj is the percentage of short-circuit voltage between the f-th winding and the j-th winding; Z fj is the total complex impedance between the f-th winding and the j-th winding; when f,j = 1, it is the high-voltage winding; when f,j = 2, it is the medium-voltage winding; when f,j = 3, it is the low-voltage winding; S N is the transformer capacity; the unit is kVA; U N is the rated voltage of the high-voltage winding of the transformer; real() is the real-part function; imag() is the imaginary-part function; f,j = 1, 2, 3 and f ≠ j.

[0132] As Figures 2 to 5 shown, the three-winding transformer is set according to the on-load tap-changer transformer of the SSZ11-63000 / 110 type. The transformer connection group is YNyn0d11, the rated capacity is 63 MVA, the rated voltages of the high-voltage winding, the medium-voltage winding, and the low-voltage winding of the transformer are 110 / 38.5 / 10.5 kV, and the rated currents of the high-voltage winding, the medium-voltage winding, and the low-voltage winding of the transformer are 330.65 A, 944.7 A, and 3463.95 A respectively; the connection group is YNyn0d11. The total short-circuit loss of the transformer is set to 0.00404 p.u., that is, 0.00404×63000 = 254.52 kW. The short-circuit losses between the high-voltage winding and the medium-voltage winding, between the high-voltage winding and the low-voltage winding, and between the medium-voltage winding and the low-voltage winding of the transformer are all 169.68 kW. The impedance voltage between the high-voltage winding and the medium-voltage winding of the transformer is set to 0.102 p.u., that is, 10.2%; the impedance voltage between the high-voltage winding and the low-voltage winding of the transformer is set to 0.1816 p.u., that is, 18.16%; the impedance voltage between the medium-voltage winding and the low-voltage winding of the transformer is set to 0.06 p.u., that is, 6%.

[0133] In some embodiments, as Figure 2As shown, short-circuit the three phases of the high-voltage winding of the transformer, open the medium-voltage winding and the low-voltage winding, apply a first detection voltage between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding, and synchronously collect the first three-phase current vector flowing into the transformer, the first neutral-point current vector, and the first voltage vector between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding to obtain the first complex impedance of each phase of the high-voltage winding to the low-voltage winding and the first total complex impedance of the three phases of the high-voltage winding to the low-voltage winding.

[0134] Among them, after applying the first detection voltage, the synchronously collected first three-phase current vectors are all -i11.022 A, the first neutral-point current vector is -i33.065 A, and the first voltage vector is 384.422 - i5.69 V. The first complex impedance of each phase of the high-voltage winding to the low-voltage winding calculated is 0.516 + i34.879 Ω, and the first total complex impedance of the three phases of the high-voltage winding to the low-voltage winding is 0.172 + i11.626 Ω.

[0135] As Figure 3 shown, short-circuit the three phases of the high-voltage winding of the transformer, short-circuit the three phases of the medium-voltage winding and the neutral point of the medium-voltage winding, open the low-voltage winding, apply a second detection voltage between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding, and synchronously collect the second three-phase current vector flowing into the transformer, the second neutral-point current vector, and the second voltage vector between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding to obtain the second complex impedance of each phase of the high-voltage winding to the medium- and low-voltage windings and the second total complex impedance of the three phases of the high-voltage winding to the medium- and low-voltage windings.

[0136] Among them, after applying the second monitoring voltage, the synchronously collected second three-phase current vectors are all -i11.022 A, the second neutral-point current vector is -i33.065 A, and the second neutral-point voltage vector is 212.644 - i6.786 V. The second complex impedance of each phase of the medium-voltage winding to the high- and low-voltage windings reduced to the high-voltage winding, that is, the second complex impedance of each phase of the high-voltage winding to the medium- and low-voltage windings, is 0.616 + i19.293 Ω, and the second total complex impedance of the three phases of the high-voltage winding to the medium- and low-voltage windings is 0.205 + i6.431 Ω.

[0137] As Figure 4 shown, short-circuit the three phases of the medium-voltage winding of the transformer, open the high-voltage winding and the low-voltage winding, apply a third detection voltage between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding, and synchronously collect the third three-phase current vector flowing into the transformer, the third neutral-point current vector, and the third voltage vector between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding to obtain the impedance of the medium-voltage winding to the low-voltage winding, the third complex impedance of each phase of the medium-voltage winding to the low-voltage winding reduced to the high-voltage winding, and the third total complex impedance of the three phases of the medium-voltage winding to the low-voltage winding.

[0138] Among them, after applying the third detection voltage, the third three-phase currents collected synchronously are all -i31.5 A, the third neutral point current vector is -i94.5 A, and the third neutral point voltage is 44.467 - i1.996 V. The third complex impedance of each phase of the medium-voltage winding with respect to the low-voltage winding reduced to the high-voltage winding is 0.517 + i11.524 Ω, and the three-phase third total complex impedance of the medium-voltage winding with respect to the low-voltage winding is 0.172 + i3.841 Ω;

[0139] As Figure 5 shown, short-circuit the three phases of the medium-voltage winding of the transformer, short-circuit the three phases of the high-voltage winding and the neutral point of the high-voltage winding, and open the low-voltage winding. Apply the fourth detection voltage between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding and synchronously collect the fourth three-phase current vector, the fourth neutral point current vector, and the fourth voltage vector between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding, and obtain the fourth complex impedance of each phase of the medium-voltage winding with respect to the high- and low-voltage windings reduced to the high-voltage winding and the three-phase fourth total complex impedance of the medium-voltage winding with respect to the high-voltage winding.

[0140] Among them, after applying the fourth monitoring voltage, the fourth three-phase current vectors collected synchronously are all -i31.5 A, the fourth neutral point current vector is -i94.5 A, and the fourth neutral point voltage vector is 24.585 - i1.524 V. The fourth complex impedance of each phase of the medium-voltage winding with respect to the high- and low-voltage windings reduced to the high-voltage winding is 0.395 + i6.371 Ω, and the three-phase fourth total complex impedance of the medium-voltage winding with respect to the high-voltage winding is 0.132 + i2.124 Ω.

[0141] In this embodiment, the first complex impedance of each phase is the same, the second complex impedance of each phase is the same, the third complex impedance of each phase is the same, and the fourth complex impedance of each phase is the same. Therefore, only one phase needs to be calculated.

[0142] Specifically, taking phase A as an example, write the first complex impedance equation of phase A:

[0143] Z 1sp =Z Ip +Z IIIp =0.516 + i34.879 Ω;

[0144] Write the second complex impedance equation of phase A:

[0145] Write the third complex impedance equation of phase A: Z 3sp =Z IIp +Z IIIp =0.517 + i11.524 Ω;

[0146] Write the fourth complex impedance equation of phase A:

[0147] Take the first complex impedance equation of phase A, the second complex impedance equation of phase A, and the third complex impedance equation of phase A to form the corresponding system of equations:

[0148] By solving the above system of equations, the complex impedance of phase A of the high-voltage winding is obtained as 0.258 + i21.473 Ω; the complex impedance of phase A of the medium-voltage winding of the transformer reduced to the high-voltage winding of the transformer is calculated as 0.259 - i1.882 Ω; the complex impedance of phase A of the low-voltage winding of the transformer reduced to the high-voltage winding of the transformer is calculated as 0.258 + i13.406 Ω.

[0149] In some embodiments, write the first total complex impedance equation: Z 1a = Z I + Z III = 0.172 + i11.626 Ω;

[0150] Write the second total complex impedance equation:

[0151] Write the third total complex impedance equation: Z 3a = Z II + Z III = 0.172 + i3.841 Ω;

[0152] Write the fourth total complex impedance equation:

[0153] Take the first total complex impedance equation, the second total complex impedance equation, and the third total complex impedance equation to form the corresponding system of equations:

[0154] By solving the above system of equations, the total complex impedance of the high-voltage winding of the transformer is obtained as: 0.086 + i7.158 Ω; the total complex impedance of the medium-voltage winding of the transformer reduced to the high-voltage winding of the transformer is: 0.086 - i0.627 Ω; the total complex impedance of the low-voltage winding of the transformer reduced to the high-voltage winding of the transformer is: 0.086 + i4.469 Ω.

[0155] Furthermore, the complex impedance Z 12 or Z 21 between the high-voltage winding and the medium-voltage winding of the transformer is:

[0156] Z 12 = Z 21 = Z Ⅰ + Z Ⅱ = 0.172 + i6.531 Ω

[0157] The total complex impedance Z 13 or Z 31 between the high-voltage winding and the low-voltage winding of the transformer is calculated by the following formula:

[0158] Z 13 = Z 31 = Z Ⅰ + Z Ⅲ = 0.172 + i11.627 Ω

[0159] The total complex impedance Z of the medium-voltage winding of the transformer referred to the high-voltage winding with respect to the low-voltage winding 23 or Z 32 is calculated by the following formula:

[0160] Z 23 = Z 32 = Z Ⅱ + Z Ⅲ = 0.172 + i3.842 Ω

[0161] The short-circuit loss and the percentage of short-circuit voltage between the windings of the transformer are calculated by the following formula:

[0162]

[0163] where P fj is the short-circuit loss between the f-th winding and the j-th winding; U fj is the percentage of short-circuit voltage between the f-th winding and the j-th winding; Z fj is the total complex impedance between the f-th winding and the j-th winding; when f,j = 1, it is the high-voltage winding; when f,j = 2, it is the medium-voltage winding; when f,j = 3, it is the low-voltage winding; S N is the transformer capacity; U N is the rated voltage of the high-voltage winding of the transformer; real() is the real part extraction function; imag() is the imaginary part extraction function; f,j = 1, 2, 3 and f ≠ j.

[0164] The calculated short-circuit loss of the high-voltage winding of the transformer and the medium-voltage winding of the transformer is 169.26 kW, and the impedance voltage is 10.2%; the calculated short-circuit loss of the high-voltage winding of the transformer and the low-voltage winding of the transformer is 169.26 kW, and the impedance voltage is 18.16%; the calculated short-circuit loss of the medium-voltage winding of the transformer and the low-voltage winding of the transformer is 169.26 kW, and the impedance voltage is 6%.

[0165] It can be seen that the calculated short-circuit loss of the high-voltage winding of the transformer and the medium-voltage winding of the transformer differs from the set value by 0.42 kW, and the error is 0.25%; the calculated result of the short-circuit loss of the high-voltage winding of the transformer and the low-voltage winding of the transformer differs from the set value by 0.42 kW, and the error is 0.25%; the calculated result of the short-circuit loss of the medium-voltage winding of the transformer and the low-voltage winding of the transformer differs from the set value by 0.42 kW, and the error is 0.25%.

[0166] The impedance voltages of the high-voltage winding and the medium-voltage winding of the transformer, the impedance voltages of the high-voltage winding and the low-voltage winding of the transformer, and the impedance voltages of the medium-voltage winding and the low-voltage winding of the transformer are calculated to be 10.2%, 18.16%, and 6% respectively, which are the same as the set values.

[0167] It can be seen that this scheme accurately calculates the complex impedance parameters between the windings of the transformer, including the total complex impedance of the high-voltage winding to the medium-voltage winding, the high-voltage winding to the low-voltage winding, and the medium-voltage winding to the low-voltage winding reduced to the high-voltage winding, and further derives the short-circuit losses and short-circuit voltage percentages between the windings. The calculation results show that the short-circuit losses between the high-voltage winding and the medium-voltage winding, the high-voltage winding and the low-voltage winding, and the medium-voltage winding and the low-voltage winding of the transformer are 169.26 kW respectively, with a difference of only 0.42 kW from the set value and an error of only 0.25%; while the corresponding impedance voltages are 10.2%, 18.16%, and 6% respectively, which are exactly the same as the set values. This fully demonstrates the high accuracy and reliability of this scheme in measuring the short-circuit complex impedance of the transformer, provides accurate data support for the performance evaluation, design optimization, and operation and maintenance of the transformer, and effectively improves the technical level of transformer parameter measurement.

[0168] As Figure 6 shown, this application also proposes a device for measuring the short-circuit complex impedance of a transformer, including:

[0169] A single-phase power frequency power supply for providing a stable power frequency detection voltage to the winding under test;

[0170] A detection unit for synchronously collecting the corresponding current vectors and voltage vectors when the remaining windings are in a short-circuit and open-circuit combination state;

[0171] An impedance calculation unit for receiving the current vector and voltage vector data from the detection unit and calculating the first complex impedance of each phase and the first total complex impedance of three phases, the second complex impedance of each phase and the second total complex impedance of three phases, the third complex impedance of each phase and the third total complex impedance of three phases, and the fourth complex impedance of each phase and the fourth total complex impedance of three phases respectively;

[0172] A test parameter calculation unit for calculating and outputting the complex impedance parameters of the transformer according to the complex impedance of each phase and the total complex impedance of three phases calculated by the impedance calculation unit.

[0173] The above embodiments only illustrate several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. In this embodiment, the transformer refers to an AC power transformer or a commutation power transformer, including a high-voltage winding, a medium-voltage winding, and a low-voltage winding. It should be noted that through simple transformation by those skilled in the art, a two-winding transformer including only a high-voltage winding and a low-voltage winding can also be used. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. The above-disclosed is only the preferred embodiment of the present invention, and of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A synchronous vector measurement method for the short-circuit complex impedance of a transformer, characterized in that The method includes: Using a low-power single-phase power supply, applying a detection voltage to the neutral point of the winding under test, and synchronously collecting the corresponding current vectors and voltage vectors under the combined states of short-circuit and open-circuit of the remaining windings. Respectively obtaining the first complex impedance of each phase and the first total complex impedance of three phases from the high-voltage winding to the low-voltage winding, the second complex impedance of each phase and the second total complex impedance of three phases from the high-voltage winding to the medium- and low-voltage windings, and the third complex impedance of each phase and the third total complex impedance of three phases from the medium-voltage winding to the low-voltage winding according to the corresponding current vectors and voltage vectors. Calculating the complex impedance parameters of the transformer through the first complex impedance of each phase and the first total complex impedance of three phases, the second complex impedance of each phase and the second total complex impedance of three phases, and the third complex impedance of each phase and the third total complex impedance of three phases.

2. A method for synchronously measuring the short-circuit complex impedance vector of a transformer according to claim 1, characterized in that, The step of using a low-power single-phase power supply, applying a detection voltage to the neutral point of the winding under test, and synchronously collecting the corresponding current vectors and voltage vectors under the combined states of short-circuit and open-circuit of the remaining windings specifically includes: Short-circuiting the three phases of the high-voltage winding of the transformer, opening the medium-voltage winding and the low-voltage winding, applying a first detection voltage between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding, and synchronously collecting the first three-phase current vector flowing into the transformer, the first neutral point current vector, and the first voltage vector between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding. Short-circuiting the three phases of the high-voltage winding of the transformer, short-circuiting the three phases and the neutral point of the medium-voltage winding, opening the low-voltage winding, applying a second detection voltage between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding, and synchronously collecting the second three-phase current vector flowing into the transformer, the second neutral point current vector, and the second voltage vector between the short-circuit point of the high-voltage winding and the neutral point of the high-voltage winding. Short-circuiting the three phases of the medium-voltage winding of the transformer, opening the high-voltage winding and the low-voltage winding, applying a third detection voltage between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding, and synchronously collecting the third three-phase current vector flowing into the transformer, the third neutral point current vector, and the third voltage vector between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding. Short-circuiting the three phases of the medium-voltage winding of the transformer, short-circuiting the three phases and the neutral point of the high-voltage winding, opening the low-voltage winding, applying a fourth detection voltage between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding, and synchronously collecting the fourth three-phase current vector flowing into the transformer, the fourth neutral point current vector, and the fourth voltage vector between the short-circuit point of the medium-voltage winding and the neutral point of the medium-voltage winding.

3. A method for synchronously measuring the short-circuit complex impedance vector of a transformer according to claim 1, characterized in that, Determining the first complex impedance of each phase from the high-voltage winding to the low-voltage winding and the second complex impedance of each phase from the high-voltage winding to the medium- and low-voltage windings according to the following formulas: where \(i = 1, 2\); \(Z\) 1sp is the first complex impedance of the p-phase of the high-voltage winding with respect to the low-voltage winding; is the first voltage vector; is the first current vector of the p-phase; \(Z\) 2sp is the second complex impedance of the p-phase of the high-voltage winding with respect to the neutral and low-voltage windings; is the second voltage vector; is the second current vector of the p-phase; Determining the third complex impedance of each phase from the medium-voltage winding to the low-voltage winding and the fourth complex impedance of each phase from the medium-voltage winding to the high- and low-voltage windings according to the following formulas: where m = 3, 4; Z 3sp is the third complex impedance of phase p of the medium-voltage winding referred to the high-voltage winding with respect to the low-voltage winding; is the third voltage vector; is the third current vector of phase p; Z 4sp is the fourth complex impedance of phase p of the medium-voltage winding referred to the high-voltage winding with respect to the high- and low-voltage windings; is the fourth voltage vector; is the fourth current vector of phase p; k 12 is the rated voltage ratio between the high-voltage winding and the medium-voltage winding.

4. A method for synchronously measuring the short-circuit complex impedance vector of a transformer according to any one of claims 4, characterized in that, Determining the first total complex impedance of three phases from the high-voltage winding to the low-voltage winding and the second total complex impedance of three phases from the high-voltage winding to the medium- and low-voltage windings according to the following formulas: where i = 1, 2; Z 1a is the three-phase first total complex impedance of the high-voltage winding with respect to the low-voltage winding; is the first voltage vector; is the first neutral point current vector; Z 2a is the three-phase second total complex impedance of the high-voltage winding with respect to the neutral and low-voltage windings; is the second voltage vector; is the second neutral point current vector; Determining the third total complex impedance of three phases from the medium-voltage winding to the low-voltage winding and the fourth total complex impedance of three phases from the medium-voltage winding to the high-voltage winding according to the following formulas: where m = 3, 4; Z 3a is the three-phase third total complex impedance of the medium-voltage winding with respect to the low-voltage winding; is the third voltage vector; is the third neutral point current vector; k 12 is the rated voltage ratio of the high-voltage winding to the medium-voltage winding; Z 4a is the three-phase fourth total complex impedance of the medium-voltage winding with respect to the high- and low-voltage windings; is the fourth voltage vector; is the fourth neutral point current vector.

5. A method for synchronously measuring the short-circuit complex impedance vector of a transformer according to claim 1, characterized in that, By using the first complex impedance of each phase, the second complex impedance of each phase, the third complex impedance of each phase, and the fourth complex impedance of each phase, the complex impedance parameters of each phase of each winding reduced to the high-voltage winding are calculated, including: For phase p, write the first complex impedance equation for phase p: Z 1sp = Z Ip + Z IIIp ; Write the p-phase second complex impedance equation: Write the third complex impedance equation for the p-phase: Z 3sp = Z IIp + Z IIIp ; Write the fourth complex impedance equation for the p-phase: Arbitrarily select three equations from the first complex impedance equation of the p phase, the second complex impedance equation of the p phase, the third complex impedance equation of the p phase, and the fourth complex impedance equation of the p phase to form a first set of equations; Solve the first set of equations to obtain the complex impedance parameters of the p phase of each winding; Among them, Z 1sp is the first complex impedance of phase p; Z 2sp is the second complex impedance of phase p; Z 3sp is the third complex impedance of phase p; Z 4sp is the fourth complex impedance of phase p; Z Ip is the complex impedance of phase p of the high-voltage winding; Z IIp is the complex impedance of phase p of the medium-voltage winding; Z IIIp is the complex impedance of phase p of the low-voltage winding.

6. A method for synchronously measuring the short-circuit complex impedance vector of a transformer according to claim 1, characterized in that, By using the first total complex impedance of the three phases, the second total complex impedance of the three phases, the third total complex impedance of the three phases, and the fourth total complex impedance of the three phases, the complex impedance parameters of each winding reduced to the high-voltage winding are calculated, including: Write the first total complex impedance equation: Z 1a = Z I + Z III ; Write the second total complex impedance equation: Write the third total complex impedance equation: Z 3a = Z II + Z III ; Write out the fourth total complex impedance equation: Arbitrarily select three equations from the first total complex impedance equation, the second total complex impedance equation, the third total complex impedance equation, and the fourth total complex impedance equation to form a second set of equations; Solve the second set of equations to obtain the complex impedance of each winding; Among them, Z 1a is the three-phase first total complex impedance; Z 2a is the three-phase first total complex impedance; Z 3a is the three-phase first total complex impedance; Z 4a is the three-phase first total complex impedance; Z I is the complex impedance of the high-voltage winding; Z II is the complex impedance of the medium-voltage winding referred to the high-voltage winding; Z III is the complex impedance of the low-voltage winding referred to the high-voltage winding.

7. A method for synchronously measuring the short-circuit complex impedance vector of a transformer according to claim 1, characterized in that After calculating the complex impedance parameters of the transformer, the method further includes calculating the short-circuit loss and the percentage of short-circuit voltage of the transformer: Calculate the total complex impedance between each winding of the transformer; Determine the short-circuit loss and the percentage of short-circuit voltage of the transformer according to the total complex impedance between each winding.

8. A method for synchronously measuring the short-circuit complex impedance vector of a transformer according to claim 7, characterized in that The calculation of the total complex impedance between each winding of the transformer specifically includes: Determine the complex impedance Z between the high-voltage winding and the medium-voltage winding of the transformer according to the following formula 12 or Z 21 and the complex impedance Z between the high-voltage winding and the low-voltage winding of the transformer 13 or Z 31 and the complex impedance Z of the medium-voltage winding to the low-voltage winding referred to the high-voltage winding of the transformer 23 or Z 32 : Z in = Z ni = Z i + Z n where, i = 1, 2; n = 2, 3; Z 12 and Z 21 are the complex impedances between the high-voltage winding and the medium-voltage winding of the transformer; Z Ⅰ is the complex impedance of the high-voltage winding; Z Ⅱ is the complex impedance of the medium-voltage winding referred to the high-voltage winding; Z 13 and Z 31 are the complex impedances between the high-voltage winding and the low-voltage winding of the transformer; Z Ⅰ is the complex impedance of the high-voltage winding; Z 23 and Z 32 are the complex impedances between the medium-voltage winding and the low-voltage winding of the transformer; Z Ⅱ is the complex impedance of the medium-voltage winding referred to the high-voltage winding; Z Ⅲ is the complex impedance of the low-voltage winding referred to the high-voltage winding.

9. A method for synchronously measuring the short-circuit complex impedance vector of a transformer according to claim 8, characterized in that, The determination of the short-circuit loss and the percentage of short-circuit voltage of the transformer according to the total complex impedance between each winding specifically includes: Determine the short-circuit loss and the percentage of short-circuit voltage between each winding of the transformer according to the following formula: Among them, Pf j is the short-circuit loss between the f-th winding and the j-th winding; Uf j is the percentage of short-circuit voltage between the f-th winding and the j-th winding; Z fj is the total complex impedance between the f-th winding and the j-th winding; when f,j = 1, it is the high-voltage winding; when f,j = 2, it is the medium-voltage winding; when f,j = 3, it is the low-voltage winding; S N is the transformer capacity; the unit is kVA; U N is the rated voltage of the high-voltage winding of the transformer; real() is the function of taking the real part; imag() is the function of taking the imaginary part; f,j = 1, 2, 3 and f ≠ j.

10. A transformer short-circuit complex impedance measurement device, characterized in that, Including: A single-phase power frequency power supply for providing a stable power frequency detection voltage to the winding under test; A detection unit for synchronously collecting corresponding current vectors and voltage vectors when the remaining windings are in a short-circuit and open-circuit combination state; An impedance calculation unit for receiving the current vector and voltage vector data from the detection unit and respectively calculating the first complex impedance of each phase and the first total complex impedance of the three phases, the second complex impedance of each phase and the second total complex impedance of the three phases, the third complex impedance of each phase and the third total complex impedance of the three phases, and the fourth complex impedance of each phase and the fourth total complex impedance of the three phases; A test parameter calculation unit for calculating and outputting the complex impedance parameters of the transformer according to the complex impedance of each phase and the total complex impedance of the three phases calculated by the impedance calculation unit.

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