A method, device and electronic equipment for identifying faults in the excitation winding of a generator

Abstract

The present invention belongs to the field of generator detection technology and relates to a method, device, and electronic device for identifying faults in a generator excitation winding. The method comprises: sampling the current of a branch group of a generator stator winding to obtain three-phase current data; using Clark transformation to transform the three-phase current data into two-phase current data; representing the two-phase current in a two-dimensional coordinate system to obtain the coordinate points of the two-phase current; obtaining, based on the coordinate points of the two-phase current, the trajectory of the coordinate points of the two-phase current changing with time in the two-dimensional coordinate system; fitting a circular curve to the trajectory; calculating the center offset of the fitted circle based on the expression of the fitted circle equation; and analyzing the fault state of the generator excitation winding. The present invention is not affected by inherent unbalanced current, does not have a monitoring dead zone, can realize the monitoring of small-turn short-circuit faults, does not require modification of the generator, and can realize sensitive identification of small-turn short-circuit faults, and can be widely used in practice.

Description

Technical Field

[0001] The present invention belongs to the technical field of power systems, and in particular relates to a method, device and electronic equipment for identifying faults in a generator excitation winding. Background Art

[0002] Generators are a key component of power systems, and their safe operation is essential for ensuring their stability. For generators operating for extended periods, excitation winding failures are common. While the initial characteristics of a short-circuit fault are subtle and have minimal impact on the generator's normal operation, if the fault is not promptly corrected, the spread of the short-circuit fault can lead to an increase in the generator's excitation current and a decrease in reactive power, causing violent oscillations in the unit and ultimately a serious short-circuit fault, potentially leading to an accident. Furthermore, inter-turn short-circuit faults (referred to as dynamic inter-turn short-circuit faults) caused by compression between the excitation windings and insufficient heat dissipation during generator operation often disappear after the generator shuts down, making them undetectable by on-site offline detection methods.

[0003] For an ideal generator, the spatial distribution of the faulty excitation magnetomotive force (MMF) caused by a fault in the field winding is no longer symmetrical, resulting in unbalanced currents between the same-phase branches of the stator winding. Existing methods have achieved online fault identification based on the effective value of the unbalanced current. However, real-world generators are not ideal motors. Factors such as poor manufacturing processes cause distortion of the excitation MMF during normal operation, resulting in inherent unbalanced currents. The presence of inherent unbalanced currents results in dead zones in existing fault identification methods, making it impossible to sensitively identify small-turn short-circuit faults. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method, device and electronic equipment for identifying generator excitation winding faults.

[0005] In a first aspect, the present disclosure provides a method for identifying a fault in an excitation winding of a generator, comprising:

[0006] Current sampling is performed on the branch group current of the generator stator winding to obtain three-phase current data;

[0007] Performing Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data;

[0008] Representing the two-phase currents in the two-phase current data in a two-dimensional coordinate system, with one phase current serving as the abscissa in the two-dimensional coordinate system and the other phase current serving as the ordinate in the two-dimensional coordinate system, to obtain coordinate points of the two-phase currents;

[0009] According to the coordinate points of the two-phase currents, the trajectory of the coordinate points of the two-phase currents changing with time in the two-dimensional coordinate system is obtained;

[0010] Performing circular curve fitting on the trajectory to obtain an expression for a fitting circle equation;

[0011] Calculating the center offset of the fitted circle according to the expression of the fitted circle equation;

[0012] The fault state of the generator excitation winding is analyzed according to the center offset of the fitting circle.

[0013] In a second aspect, the present disclosure provides a generator excitation winding fault identification device, comprising: a sampling unit, a transformation unit, a conversion unit, a trajectory generation unit, a fitting unit, a calculation unit, and an analysis and identification unit;

[0014] The sampling unit is used to sample the current of the branch group of the generator stator winding to obtain three-phase current data;

[0015] The transformation unit is configured to perform Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data;

[0016] The conversion unit is used to convert the two-phase currents in the two-phase current data into coordinate points in a two-dimensional coordinate system, with one phase current serving as the abscissa in the two-dimensional coordinate system and the other phase current serving as the ordinate in the two-dimensional coordinate system, to obtain the coordinate points of the two-phase currents;

[0017] The trajectory generating unit is used to obtain the trajectory of the coordinate points of the two-phase current changing with time in a two-dimensional coordinate system according to the coordinate points of the two-phase current;

[0018] The fitting unit is used to perform circular curve fitting on the trajectory to obtain an expression of the fitted circle equation;

[0019] The calculation unit is used to calculate the center offset of the fitting circle according to the expression of the fitting circle equation;

[0020] The analysis and identification unit analyzes and identifies the fault state of the generator excitation winding according to the center offset of the fitting circle.

[0021] In a third aspect, the present disclosure provides an electronic device, comprising:

[0022] processor and memory;

[0023] The memory is used to store computer operating instructions;

[0024] The processor is used to execute any one of the methods for identifying a generator excitation winding fault by calling the computer operation instructions.

[0025] The beneficial effects of the present invention are as follows: the present invention is not affected by inherent unbalanced current, has no monitoring dead zone, can monitor small-turn short-circuit faults, does not require modification of the generator, and can sensitively identify small-turn short-circuit faults, and can be widely used in practice.

[0026] On the basis of the above technical solution, the present invention can also be improved as follows.

[0027] Furthermore, if the stator winding of the generator is a multi-branch parallel structure per phase, the current of one branch per phase is sampled.

[0028] Further, performing Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data includes:

[0029] By equivalently transforming the stator three-phase current into a two-dimensional coordinate system, we can obtain the relationship that the vector sum of the three-phase current is equal to the vector sum of the two-phase current;

[0030] Obtain the expression of the phase current of each phase stator winding when the generator is operating normally;

[0031] Substituting the expressions of the phase currents of the stator windings of each phase into the above relationship, the expressions of the two-phase currents are obtained.

[0032] Furthermore, when the generator is operating without an excitation winding fault, after the three-phase current data is transformed by Clark, the trajectory of the coordinate points in the two-dimensional coordinate system obtained as a function of time is a circle with the center coordinate located at the origin and a radius that is a multiple of the set current amplitude of the stator winding.

[0033] Further, analyzing and identifying the fault state of the generator excitation winding according to the center offset of the fitting circle includes:

[0034] It is determined whether the ratio of the center offset of the fitting circle to the set value is greater than or equal to a threshold value; if so, the generator excitation winding fails; otherwise, the generator excitation winding does not fail. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A flow chart of a method for identifying a generator excitation winding fault provided in Example 1 of the present invention;

[0036] Figure 2 This is a flowchart of a method for identifying a fault in a generator excitation winding according to embodiment 1 of the present invention;

[0037] Figure 3 The schematic diagram of Clark transformation;

[0038] Figure 4Clark transformation waveform diagram of the stator three-phase current under different working conditions of the experimental prototype and its center offset simulation diagram;

[0039] Figure 5 The Clark transformation waveform of the stator three-phase current and the center offset simulation diagram of the fitting circle when the experimental prototype has both faults and inherent unbalanced currents;

[0040] Figure 6 This is a statistical diagram of the center offset of the Clark transform waveform fitting circle when the experimental prototype considers different turns faults with inherent unbalanced current;

[0041] Figure 7 A schematic diagram of a generator excitation winding fault identification device provided in Example 2 of the present invention;

[0042] Figure 8 This is the simulation diagram of the three-phase current of the stator winding and its Clark transformation waveform under normal working conditions of the generator;

[0043] Figure 9 The Clark transformation waveform simulation diagram of the three-phase current of the stator winding when the generator excitation winding has different turns faults;

[0044] Figure 10 The fault identification sensitivity coefficient table based on Clark transformation for short circuits with different numbers of turns;

[0045] Figure 11 This is a schematic diagram of an electronic device provided in Example 3 of the present invention.

[0046] Icon: 50 - electronic device; 510 - processor; 520 - bus; 530 - memory; 540 - transceiver. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0048] Example 1

[0049] As an example, Figure 1 As shown, to solve the above technical problems, this embodiment provides a method for identifying faults in a generator excitation winding, comprising:

[0050] Current sampling is performed on the branch group current of the generator stator winding to obtain three-phase current data;

[0051] Performing Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data;

[0052] Converting the two-phase currents in the two-phase current data into coordinate points in a two-dimensional coordinate system, with one phase current serving as the abscissa in the two-dimensional coordinate system and the other phase current serving as the ordinate in the two-dimensional coordinate system, to obtain the coordinate points of the two-phase currents;

[0053] According to the coordinate points of the two-phase currents, the trajectory of the coordinate points of the two-phase currents changing with time in the two-dimensional coordinate system is obtained;

[0054] Performing circular curve fitting on the trajectory to obtain an expression for a fitting circle equation;

[0055] Calculating the center offset of the fitted circle according to the expression of the fitted circle equation;

[0056] The fault state of the generator excitation winding is identified based on the analysis of the center offset of the fitting circle.

[0057] Specifically, the generator excitation winding fault identification method includes:

[0058] Sampling the current of a branch or a group of branches of the generator stator winding;

[0059] The collected three-phase current data is transformed by Clark to transform the ABC three-phase current into the two-phase current i α with i β ;

[0060] The obtained two-phase current i α Set as the horizontal axis coordinate in the αβ two-dimensional coordinate system, and set i β Set as the vertical axis coordinate in the two-dimensional coordinate system;

[0061] According to the coordinate points of the two-phase currents, the trajectory of the coordinate points of the two-phase currents changing with time in the two-dimensional coordinate system is obtained;

[0062] Fitting the circular curve, the expression of the fitted circle equation is:

[0063] (i α -i α0 ) 2 +(i β -i β0 ) 2 =r 2 ;

[0064] Where: i α0 is the horizontal coordinate of the center of the fitting circle in the αβ two-dimensional coordinate system, i β0 is the ordinate of the center of the fitting circle in the αβ two-dimensional coordinate system, and r is the radius of the fitting circle;

[0065] According to the expression of the fitting circle equation, the center offset c of the fitting circle is calculated. k :

[0066] c k =i α0 2 +i β0 2 ;

[0067] The generator excitation winding fault is identified by analyzing the size of the center offset of the fitting circle.

[0068] Optionally, if the stator winding of the generator is a multi-branch parallel structure per phase, the current of one branch per phase is sampled.

[0069] Optionally, performing Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data includes:

[0070] By equivalently transforming the stator three-phase current into a two-dimensional coordinate system, we can obtain the relationship that the vector sum of the three-phase current is equal to the vector sum of the two-phase current;

[0071] Obtain the expression of the phase current of each phase stator winding when the generator is operating normally;

[0072] Substituting the expressions of the phase currents of the stator windings of each phase into the above relationship, the expressions of the two-phase currents are obtained.

[0073] In practical applications, the stator three-phase current is equivalently transformed into the αβ two-dimensional coordinate system. The vector sum of the three-phase current is equal to the vector sum of the two-phase current. Taking the stator three-phase current as an example, the relationship between the currents iα and iβ in the αβ two-dimensional coordinate system and the stator currents iA, iB, and iC in the coordinate system where the ABC three-phase current is located is:

[0074]

[0075] Assuming that there is no excitation winding fault during normal operation of the generator, the expression of the stator winding A phase current is:

[0076] i A =Isinω r t;

[0077] Where I is the stator winding current amplitude, ω r is the synchronous speed.

[0078] Substituting the expressions of stator currents iA, iB, and iC into the above relationship, we get:

[0079]

[0080] Simplified:

[0081]

[0082] Optionally, when the generator is operating without an excitation winding fault, after the three-phase current data is transformed by Clark, the trajectory of the coordinate points in the two-dimensional coordinate system obtained as a function of time is a circle with the center coordinate at the origin and a radius that is a multiple of the set current amplitude of the stator winding.

[0083] From the above formula, it can be obtained that the three-phase current of the generator stator is symmetrical. Transforming the three-phase current of the generator stator into the αβ coordinate system can be obtained:

[0084]

[0085] Therefore, when the generator is operating normally and there is no excitation winding fault, the three-phase current of the generator stator is transformed by Clark to obtain the following equation in the αβ coordinate system (i α ,i β )The trajectory of its change with time is a circle with its center at the origin and a radius of 3I / 2.

[0086] Optionally, analyzing and identifying a fault state of a generator excitation winding according to the center offset of the fitting circle includes:

[0087] It is determined whether the ratio of the center offset of the fitting circle to the set value is greater than or equal to a threshold value; if so, the generator excitation winding fails; otherwise, the generator excitation winding does not fail.

[0088] In actual applications, when a generator has an excitation winding fault, the excitation magnetomotive force in space is no longer symmetrically distributed, and the three-phase current of the generator stator induced by this will also be distorted. At this time, the stator currents iA, iB, and iC no longer satisfy the trajectory of a circle with a center at the origin and a radius of 3I / 2 after Clark transformation. A circular curve fitting is performed on the expression after Clark transformation, and the distortion characteristics of the fitted circle are used to realize the identification of excitation winding faults.

[0089] For example, when When the generator excitation winding fault occurs; k is the maximum center offset value f setThe threshold is a preset value, selected based on the maximum center offset of the Clark transform waveform of the three-phase currents A, B, and C under normal generator operation. Under ideal normal generator operation, the Clark transform waveform is a perfect circle with no center offset. Inherent unbalanced current distorts the Clark transform waveform into an ellipse, resulting in a nearly zero center offset. Faults, however, can cause a significant center offset in the Clark transform fitted circle. By comparing the center offset with the threshold, sensitive fault identification is achieved.

[0090] In order to verify the above method, a field-circuit coupling model of the experimental prototype was established in the ANSYS platform, and the inherent unbalanced current generated by the three conditions of stator out-of-roundness, rotor out-of-roundness and rotor eccentricity in the actual generator was simulated and calculated, as shown in the attached figure. Figure 4 shown.

[0091] As attached Figure 4-1 As shown in the figure, Q401 is the Clark transformation waveform under normal working conditions, and Q402 is the fitting circle of the waveform; under normal working conditions, the fitting circle equation of the a1, b1, and c1 branch currents in the three-phase current obtained by Clark transformation in the αβ coordinate system is:

[0092] (x-0.0026) 2 +(y-0.0720) 2 =13.5635 2 ;

[0093] As attached Figure 4-2 As shown in the figure, Q403 is the Clark transformation waveform under the fault condition, and Q404 is the fitting circle of the waveform; under the excitation winding fault condition, the circle equation of the αβ coordinate system obtained by Clark transformation of the a1, b1, and c1 branch currents in the three-phase current is obtained from the fitting circle:

[0094] (x-0.6525) 2 +(y-1.0408) 2 =12.4439 2 ;

[0095] As attached Figure 4-3 As shown in the figure, Q405 is the Clark transformation waveform under the stator out-of-round condition, and Q406 is the fitting circle of the waveform. Under the stator out-of-round condition, the circle equation of the αβ coordinate system obtained by Clark transformation of the a1, b1, and c1 branch currents in the three-phase current is:

[0096] (x-0.006) 2 +(y-0.0127) 2 =13.5208 2 ;

[0097] As attached Figure 4-4 As shown in the figure, Q407 is the Clark transformation waveform under the rotor out-of-round condition, and Q408 is the fitting circle of the waveform. Under the rotor out-of-round condition, the circle equation of the αβ coordinate system obtained by Clark transformation of the a1, b1, and c1 branch currents in the three-phase current is:

[0098] (x-0.0806) 2 +(y-0.0116) 2 =13.3837 2 ;

[0099] As attached Figure 4-5 As shown in the figure, Q409 is the Clark transformation waveform under the rotor eccentricity condition, and Q410 is the fitting circle of the waveform. Under the rotor eccentricity condition, the circle equation of the αβ coordinate system obtained by Clark transformation of the a1, b1, and c1 branch currents in the three-phase current is:

[0100] (x-0.0861) 2 +(y-0.0275) 2 =12.9651 2 ;

[0101] According to the above equation, the center offset of the fitting circle under each working condition is calculated as shown in the attached figure. Figure 4-6 As shown in the figure, the data show that the coordinates of the center of the fitting circle in the fault condition have obvious changes compared with the normal working condition, but the offset of the coordinates of the center of the fitting circle obtained when there is an inherent unbalanced current is smaller. Therefore, by combining the Clark transform and the center offset obtained by the fitting circle, the fault unbalanced current and the inherent unbalanced current can be distinguished.

[0102] The simulation of the generator excitation winding fault is obtained by the ideal motor model. In actual application, the generator excitation winding fault and the inherent unbalanced current exist at the same time. In order to further verify the effectiveness of the method of the present invention, the fault condition of the inherent unbalanced current is considered for simulation. The waveform obtained by Clark transformation is shown in the attached figure. Figure 5 As shown, attached Figure 5-1 5-2, 5-3 Under the fault condition with inherent unbalanced current, the center offset value of the fitting circle obtained by Clark transformation of the stator winding a1, b1, c1 branch current is shown in the attached figure. Figure 5-4 As shown, Figure 5-1 Q501 is the Clark transform waveform of the faulty stator and the stator is out of round, and Q502 is the fitting curve of the waveform; Figure 5-2 Q503 is the Clark transform waveform of the faulty rotor and out-of-roundness, and Q504 is the fitting curve of the waveform; Figure 5-3Q505 is the Clark transform waveform of the faulty rotor and eccentricity, and Q506 is the fitting curve of the waveform. The results in the figure show that the effectiveness of the fault identification method based on Clark transform is not affected by the inherent unbalanced current.

[0103] Sensitivity analysis of the generator excitation winding fault identification method of the present invention:

[0104] Under the rotor eccentricity condition obtained by the fitting circle, the maximum center deviation caused by the inherent unbalanced current can be 0.0082. If the reliability coefficient is 1.2, the setting value f of the fault identification is set is 0.0098. In order to reflect the sensitivity of the fault identification method, the sensitivity coefficient k of fault identification is introduced. sen , the calculation method of the sensitivity coefficient is:

[0105]

[0106] The sensitivity coefficient obtained is different for different short-circuit turns. If the sensitivity coefficient k obtained for a certain fault is sen ≥1.3, the generator excitation winding fault identification method of the present invention has good sensitivity. Since the fault identification setting value is set according to the center offset value obtained by rotor eccentricity, the experimental prototype excitation winding 1-turn, 2-turn and 3-turn short-circuit faults and the existence of rotor eccentricity are simulated and calculated. The center offset values of the fitting circle obtained by simulation calculation under each working condition are shown in the attached figure. Figure 6 As shown in the figure, the sensitivity coefficients under the three fault conditions are 1.54, 2.03 and 2.59 respectively. It can be seen that for the experimental prototype, the sensitivity coefficient when short-circuiting one turn has met the requirements (k sen ≥1.3), which shows that the fault identification method based on Clark transform has good sensitivity and no dead zone.

[0107] Example 2

[0108] Based on the same principle as the method shown in Example 1 of the present invention, as shown in the attached Figure 7 As shown, an embodiment of the present invention further provides a generator excitation winding fault identification device, comprising: a sampling unit, a transformation unit, a conversion unit, a trajectory generation unit, a fitting unit, a calculation unit and an analysis and identification unit;

[0109] The sampling unit is used to sample the current of the branch group of the generator stator winding to obtain three-phase current data;

[0110] The transformation unit is configured to perform Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data;

[0111] The conversion unit is used to convert the two-phase currents in the two-phase current data into coordinate points in a two-dimensional coordinate system, with one phase current serving as the abscissa in the two-dimensional coordinate system and the other phase current serving as the ordinate in the two-dimensional coordinate system, to obtain the coordinate points of the two-phase currents;

[0112] The trajectory generating unit is used to obtain the trajectory of the coordinate points of the two-phase current changing with time in a two-dimensional coordinate system according to the coordinate points of the two-phase current;

[0113] The fitting unit is used to perform circular curve fitting on the trajectory to obtain an expression of the fitted circle equation;

[0114] The calculation unit is used to calculate the center offset of the fitting circle according to the expression of the fitting circle equation;

[0115] The analysis and identification unit analyzes and identifies the fault state of the generator excitation winding according to the center offset of the fitting circle.

[0116] Optionally, if the stator winding of the generator is a multi-branch parallel structure per phase, the current of one branch per phase is sampled.

[0117] Optionally, performing Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data includes:

[0118] By equivalently transforming the stator three-phase current into a two-dimensional coordinate system, we can obtain the relationship that the vector sum of the three-phase current is equal to the vector sum of the two-phase current;

[0119] Obtain the expression of the phase current of each phase stator winding when the generator is operating normally;

[0120] Substituting the expressions of the phase currents of the stator windings of each phase into the above relationship, the expressions of the two-phase currents are obtained.

[0121] Optionally, when the generator is operating without an excitation winding fault, after the three-phase current data is transformed by Clark, the trajectory of the coordinate points in the two-dimensional coordinate system obtained as a function of time is a circle with the center coordinate at the origin and a radius that is a multiple of the set current amplitude of the stator winding.

[0122] Optionally, analyzing and identifying a fault state of a generator excitation winding according to the center offset of the fitting circle includes:

[0123] It is determined whether the ratio of the center offset of the fitting circle to the set value is greater than or equal to a threshold value; if so, the generator excitation winding fails; otherwise, the generator excitation winding does not fail.

[0124] In actual application, a generator is equipped with a generator excitation winding fault identification device. This device installs a total of 6 current transformers (CTs) in the stator winding in two groups. One group installs a current transformer (CT) in each of the three-phase first branches, and the other group installs a current transformer (CT) on each of the three-phase main conductors A, B, and C. This device obtains data on the three-phase current of the generator stator winding. The recorded waveforms (secondary values) of the stator winding branch currents a1, b1, and c1 under normal generator operation and their Clark transforms are shown in the attached figure. Figure 8 9-1 in i a1 、i b1 、i c1 , attached Figure 8 In Figure 9-2, Q801 is the Clark transform waveform, and Q802 is the fitting curve of the waveform.

[0125] Under normal operating conditions of the generator, the coordinates of the center of the fitting circle obtained by transforming the three-phase current of the stator winding into the αβ coordinate system are (-0.0194, 0.0194), and the center offset is 0.0008. Based on Clark transformation, the setting value f of fault identification set Take: f set =λ rel c m , where c m is the maximum center offset value, λ rel is the reliability coefficient, and c can be calculated from the field recording data. m The value is 0.0008; if the reliability coefficient λ rel is 1.2, then the setting value f of fault identification set It is 0.00096.

[0126] The Clark transformation waveforms of the stator a1, b1, and c1 branch currents are obtained from the generator simulation model when the excitation winding has different turns short-circuit faults, as shown in the attached figure. Figure 9 In, attached Figure 9-1 Q901 is the Clark transformation waveform when a 1-turn short circuit fault occurs, and Q902 is the fitting curve of the waveform. Figure 9-2 Q903 is the Clark transformation waveform when there is a 2-turn short circuit fault, and Q904 is the fitting curve of the waveform; Figure 9-3 Q905 is the Clark transformation waveform when there is a 3-turn short circuit fault, and Q906 is the fitting curve of the waveform. Figure 9-4 Q907 is the Clark transformation waveform when there is a 4-turn short circuit fault, and Q908 is the fitting curve of the waveform; Figure 9-5 Q909 is the Clark transformation waveform when there is a 5-turn short circuit fault, and Q910 is the fitting curve of the waveform; Figure 9-6Q911 is the Clark transformation waveform when there is a 6-turn short-circuit fault, and Q912 is the fitting curve of the waveform. set is 0.00096. According to the definition of sensitivity coefficient, the sensitivity coefficients obtained by Clark transformation method when the generator excitation winding has different turns faults are as shown in the attached figure. Figure 10 As shown in the table, when the number of short-circuit turns is 1, the fault identification sensitivity coefficient reaches 1.35, and the fault identification at this time is already relatively sensitive; and as the number of short-circuit turns increases, the sensitivity coefficient increases rapidly. This shows that the fault identification method based on Clark transform has good sensitivity when applied to generators.

[0127] Example 3

[0128] Based on the same principle as the method shown in the embodiment of the present invention, an electronic device is also provided in the embodiment of the present invention, as shown in the attached Figure 11 As shown, the electronic device may include but is not limited to: a processor and a memory; the memory is used to store a computer program; the processor is used to execute the method shown in any embodiment of the present invention by calling the computer program.

[0129] In an alternative embodiment, an electronic device is provided, Figure 11 The electronic device 50 shown includes a processor 510 and a memory 550 , wherein the processor 510 and the memory 550 are connected, for example, via a bus 520 .

[0130] Optionally, the electronic device 50 may further include a transceiver 540. The transceiver 540 may be used for data exchange between the electronic device and other electronic devices, such as data transmission and / or data reception. It should be noted that in actual applications, there is not limited to one transceiver 540, and the structure of the electronic device 50 does not constitute a limitation on the embodiments of the present invention.

[0131] Processor 510 may be a CPU, a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, a hardware component, or any combination thereof. Processor 510 may also be a combination that implements computing functions, such as a combination of one or more microprocessors, or a combination of a DSP and a microprocessor.

[0132] The bus 520 may include a path for transmitting information between the above components. The bus 520 may be a PCI peripheral component interconnect standard bus or an EISA extended industry standard architecture bus. The bus 520 may be divided into a control bus, a data bus, an address bus, etc. For ease of representation, Figure 11 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0133] The memory 550 can be a ROM read-only memory or other type of static storage device that can store static information and instructions, a RAM random access memory or other type of dynamic storage device that can store information and instructions, or an EEPROM electrically erasable programmable read-only memory, a CD-ROM read-only optical disc or other optical disc storage, an optical disc storage (including optical disc, laser disc, compact disc, digital versatile disc, etc.), a magnetic disk storage medium, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited to these.

[0134] The memory 550 is used to store application code (computer program) for executing the solution of the present invention, and is controlled by the processor 510. The processor 510 is used to execute the application code stored in the memory 550 to implement the content shown in the above method embodiment.

[0135] The present invention is not affected by inherent unbalanced current, has no monitoring dead zone, can monitor small-turn short-circuit faults, does not require generator modification, and can sensitively identify small-turn short-circuit faults, and can be widely used in practice.

[0136] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for identifying faults in a generator excitation winding, characterized in that: include: Current sampling is performed on the branch group current of the generator stator winding to obtain three-phase current data; Performing Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data; Converting the two-phase currents in the two-phase current data into coordinate points in a two-dimensional coordinate system, with one phase current serving as the abscissa in the two-dimensional coordinate system and the other phase current serving as the ordinate in the two-dimensional coordinate system, to obtain the coordinate points of the two-phase currents; According to the coordinate points of the two-phase currents, the trajectory of the coordinate points of the two-phase currents changing with time in the two-dimensional coordinate system is obtained; Performing circular curve fitting on the trajectory to obtain an expression for a fitting circle equation; Calculating the center offset of the fitted circle according to the expression of the fitted circle equation; The fault state of the generator excitation winding is identified based on the analysis of the center offset of the fitting circle.

2. A method for identifying faults in a generator excitation winding according to claim 1, characterized in that: If the stator winding of the generator is a multi-branch parallel structure per phase, the current of one branch per phase is sampled.

3. The method for identifying a fault in a generator excitation winding according to claim 1, wherein: Performing Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data includes: By equivalently transforming the stator three-phase current into a two-dimensional coordinate system, we can obtain the relationship that the vector sum of the three-phase current is equal to the vector sum of the two-phase current; Obtain the expression of the phase current of each phase stator winding when the generator is operating normally; Substituting the expressions of the phase currents of the stator windings of each phase into the above relationship, the expressions of the two-phase currents are obtained.

4. The method for identifying a fault in a generator excitation winding according to claim 1, wherein: When the generator is operating without an excitation winding fault, after the three-phase current data is subjected to Clark transformation, the trajectory of the coordinate points in the two-dimensional coordinate system changing with time is a circle with the center coordinate located at the origin and the radius being a multiple of the set current amplitude of the stator winding.

5. The method for identifying faults in a generator excitation winding according to claim 1, characterized in that: Analyzing and identifying a fault state of a generator excitation winding according to the center offset of the fitting circle includes: It is determined whether the ratio of the center offset of the fitting circle to the set value is greater than or equal to a threshold value; if so, the generator excitation winding fails; otherwise, the generator excitation winding does not fail.

6. A generator excitation winding fault identification device, characterized in that: include: Sampling unit, transformation unit, conversion unit, trajectory generation unit, fitting unit, calculation unit and analysis and identification unit; The sampling unit is used to sample the current of the branch group of the generator stator winding to obtain three-phase current data; The transformation unit is configured to perform Clark transformation on the three-phase current data to transform the three-phase current data into two-phase current data; The conversion unit is used to convert the two-phase currents in the two-phase current data into coordinate points in a two-dimensional coordinate system, with one phase current serving as the abscissa in the two-dimensional coordinate system and the other phase current serving as the ordinate in the two-dimensional coordinate system, to obtain the coordinate points of the two-phase currents; The trajectory generating unit is used to obtain the trajectory of the coordinate points of the two-phase current changing with time in a two-dimensional coordinate system according to the coordinate points of the two-phase current; The fitting unit is used to perform circular curve fitting on the trajectory to obtain an expression of the fitted circle equation; The calculation unit is used to calculate the center offset of the fitting circle according to the expression of the fitting circle equation; The analysis and identification unit analyzes and identifies the fault state of the generator excitation winding according to the center offset of the fitting circle.

7. An electronic device, characterized in that: include: processor and memory; The memory is used to store computer operating instructions; The processor is configured to execute a generator excitation winding fault identification method according to any one of claims 1 to 5 by calling the computer operation instruction.

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