Generator field loss protection impedance circle checking method and related equipment

Abstract

The invention discloses a generator field loss protection impedance circle checking method and related equipment, and belongs to the technical field of field loss protection, working parameters of a generator, a main transformer and a power system are simply obtained, after the parameters are obtained, the system automatically checks the field loss protection impedance circle, convenience and rapidness are achieved, different types of units are selected, and the working efficiency is improved. The system can adapt to different impedance circle calculation methods of a thermal power generating unit, a hydroelectric generating unit and the like, the intersection area of a 100% equal active impedance circle and an asynchronous boundary impedance circle and the intersection area of a static stability limit impedance circle on an impedance plane are calculated respectively, a comparison algorithm is set, and calculation results are given. And the suitability of a system calculation model is greatly expanded.

Description

Technical Field

[0001] The invention belongs to the technical field of demagnetization protection, and in particular relates to a generator demagnetization protection impedance circle calibration method and related equipment. Background Art

[0002] Demagnetization protection is a solid line of defense for the safe operation of generators. It responds quickly when the excitation system fails or the excitation level is seriously insufficient due to a fault or operating error in the generator, aiming to prevent the generator from being damaged by serious consequences such as excessive phase advance and voltage collapse, and effectively curb the chain reaction that these events may cause to the overall stability of the power system. This protection mechanism monitors the electrical parameters of the generator in real time, such as terminal voltage, reactive power, current, etc. Once it detects that the generator is in a critical state of demagnetization or has already demagnetized, it immediately takes measures, such as cutting off the generator or reducing the load, to protect the safety of the generator and the system.

[0003] As a preventive control measure, the importance of low excitation limitation is self-evident. It constantly monitors the excitation state of the generator to ensure that the generator can be "pulled back" to the safe area in time when it is close to the edge of demagnetization. Specifically, the low excitation limitation automatically starts through the preset setting value when the generator absorbs too much reactive power and the excitation current drops to a certain level, and limits its further phase advance by reducing the reactive power emitted by the generator or increasing the reactive power it absorbs. This action is more sensitive and rapid than demagnetization protection because it intervenes before the generator reaches the severity of demagnetization, thereby effectively avoiding the risk of the generator entering an unstable state.

[0004] Therefore, low excitation limit and demagnetization protection complement each other and together constitute two solid barriers for generator excitation protection. Through scientific and reasonable setting and optimization, the synergy of the two can be fully utilized to provide strong guarantee for the safe operation of the generator and the stable power supply of the power system.

[0005] The selection of the stator impedance circle is a key link in the formulation of the demagnetization protection strategy. The asynchronous boundary impedance circle is mainly designed based on the asynchronous operation state that the generator may enter after demagnetization. When the generator loses its magnetism, its operation state will gradually transition from synchronous operation to asynchronous operation. At this time, the relationship between the stator current and voltage of the generator will form a specific circular area, namely the asynchronous boundary impedance circle. The setting of this circle is intended to quickly identify the dangerous state of the generator that is about to or has entered asynchronous operation, and quickly trigger the protection action.

[0006] The static stability limit refers to the maximum power limit at which the generator can maintain synchronous and stable operation after being subjected to a small disturbance. The static stability limit impedance circle is based on this principle. It determines whether the generator is close to or exceeds its static stability limit by monitoring the specific relationship between the generator stator current and voltage. The setting of this circle pays more attention to the stability assessment of the generator in the synchronous operation state, which is of great significance for preventing the generator from losing synchronization due to insufficient excitation.

[0007] For hydropower units, since their longitudinal synchronous reactance (Xd) and transverse synchronous reactance (Xq) are usually not equal (i.e., Xd ≠ Xq), this characteristic leads to significant differences in their static stability circles from those of thermal power units. Due to the similarity in design, the Xd and Xq of thermal power units are often close, so the shape and position of their static stability circles are relatively fixed. This difference in hydropower units increases the complexity of formulating demagnetization protection strategies, and requires more detailed consideration of the specific electrical parameters and operating characteristics of the units, and the selection of impedance circles that are more in line with the actual situation on site to avoid incorrect demagnetization protection. At present, the selection of impedance circles is often determined by historical experience rather than by calculating the intersection area with the 100% equal active impedance circle, which is not conducive to protecting the generator set. Summary of the invention

[0008] The present invention provides a generator demagnetization protection impedance circle calibration method and related equipment, which solves the problem that the impedance circle is currently selected based on historical experience rather than by calculating the intersection area with the 100% equal active impedance circle.

[0009] To achieve the above object, the present invention provides the following technical solutions: A generator demagnetization protection impedance circle calibration method, comprising: Obtain operating parameters of generators, main transformers and power systems; Calculate the per unit value of the connection reactance between the generator and the power system based on the operating parameters of the generator, main transformer and power system; Calculate the 100% equal active impedance circle based on the generator operating parameters and the per unit value of the connection reactance between the generator and the power system; Calculate other impedance circles that intersect with the 100% equal active impedance circle based on the generator operating parameters; Calculate the distance between the center of the 100% equal active impedance circle and other impedance circles; Calculate the intersection area of ​​the 100% equal active impedance circle and other impedance circles based on the distance between the circle centers; The stator impedance criterion is selected based on the intersection area.

[0010] Preferably, the generator operating parameters include: Generator capacity, generator longitudinal axis synchronous reactance, generator longitudinal axis transient reactance, generator transverse axis synchronous reactance and generator power factor, among which the generator longitudinal axis synchronous reactance, generator longitudinal axis transient reactance and generator transverse axis synchronous reactance are all unsaturated values; The main transformer operating parameters include: Main transformer capacity and main transformer short-circuit impedance; Power system operating parameters include: The power system benchmark capacity and the power system minimum mode positive sequence impedance.

[0011] Preferably, the step of calculating the per unit value of the connection reactance between the generator and the power system according to the operating parameters of the generator, the main transformer and the power system is specifically: Calculate the short-circuit impedance of the main transformer to the rated capacity of the generator: Calculate the minimum positive sequence impedance of the power system to the rated capacity of the generator; Calculate the per unit value of the connection reactance between the generator and the system, and add the short-circuit impedance of the main transformer calculated to the rated capacity of the generator and the minimum positive-sequence impedance of the power system calculated to the rated capacity of the generator.

[0012] Preferably, the step of calculating the impedance circle having an intersection with the 100% equal active impedance circle according to the generator operating parameters is specifically as follows: The intersection point of the impedance circle and the 100% equal active impedance circle is obtained according to the synchronous reactance of the generator longitudinal axis and the transient reactance of the generator longitudinal axis, and the center and position of the impedance circle are determined according to the intersection point.

[0013] Preferably, the steps of calculating the 100% equal active impedance circle according to the generator operating parameters and the per unit value of the connection reactance between the generator and the power system are specifically: The ordinate of the 100% equal active impedance circle is determined according to the per unit value of the connection reactance between the generator and the power system, and the abscissa and radius of the 100% equal active impedance circle are determined according to the operating parameters of the generator.

[0014] Preferably, other impedance circles include an asynchronous boundary impedance circle, a thermal power unit static stability limit impedance circle, and a hydropower unit static stability limit impedance circle.

[0015] Preferably, the step of selecting the stator impedance criterion according to the intersection area is specifically as follows: If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is smaller than the intersection area of ​​the thermal power unit static stability limit impedance circle and the 100% equal active impedance circle, the stator impedance criterion selects the thermal power unit static stability limit impedance circle; If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is larger than the intersection area of ​​the static stability limit impedance circle of the thermal power unit and the 100% equal active impedance circle, the asynchronous boundary impedance circle is selected as the stator impedance criterion; If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is smaller than the intersection area of ​​the hydropower unit static stability limit impedance circle and the 100% equal active impedance circle, the stator impedance criterion selects the hydropower unit static stability limit impedance circle; If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is larger than the intersection area of ​​the static stability limit impedance circle of the hydropower unit and the 100% equal active impedance circle, the asynchronous boundary impedance circle is selected as the stator impedance criterion.

[0016] A generator demagnetization protection impedance circle calibration system, comprising: Parameter acquisition module: used to obtain the operating parameters of the generator, main transformer and power system; The first calculation module is used to calculate the unit value of the connection reactance between the generator and the power system according to the working parameters of the generator, the main transformer and the power system; The second calculation module is used to calculate the 100% equal active impedance circle according to the generator working parameters and the per unit value of the connection reactance between the generator and the power system; The third calculation module is used to calculate other impedance circles that intersect with the 100% equal active impedance circle according to the generator operating parameters; The fourth calculation module is used to calculate the center distance between the 100% equal active impedance circle and other impedance circles; Intersection area calculation module: used to calculate the intersection area of ​​100% equal active impedance circle and other impedance circles according to the distance between the centers of the circles; Selection module: used to select the stator impedance criterion based on the intersection area.

[0017] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, steps of a method for calibrating the impedance circle of a generator demagnetization protection are implemented.

[0018] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a generator demagnetization protection impedance circle calibration method.

[0019] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a method for calibrating the impedance circle of demagnetization protection of a generator. The working parameters of the generator, the main transformer and the power system are simple to obtain. After obtaining the above parameters, the system automatically calibrates the impedance circle of demagnetization protection, which is convenient and fast. Different types of units can be selected to adapt to different impedance circle calculation methods. The system can adapt to different impedance circle calculation methods such as thermal power units and hydropower units, and respectively calculate the intersection area of ​​the 100% equal active impedance circle with the asynchronous boundary impedance circle and the intersection area of ​​the static stability limit impedance circle on the impedance plane, set a comparison algorithm, and give the calculation results, which greatly expands the adaptability of the system calculation model. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of a generator demagnetization protection impedance circle calibration method of the present invention; Figure 2 Selecting a demagnetization protection impedance circle for the embodiment of the present invention; Figure 3 This is a static stability limit impedance diagram of a drop-shaped curve for demagnetization protection according to an embodiment of the present invention; Figure 4 The present invention is a block diagram of a generator demagnetization protection impedance circle calibration system. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 here can be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0024] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0025] like Figure 1 As shown, a generator demagnetization protection impedance circle calibration method includes: S101 obtains the operating parameters of the generator, main transformer and power system; S102 calculates the per unit value of the connection reactance between the generator and the power system according to the operating parameters of the generator, the main transformer and the power system; S103 calculates a 100% equal active impedance circle according to the generator operating parameters and the per unit value of the connection reactance between the generator and the power system; S104 calculates other impedance circles that intersect with the 100% equal active impedance circle according to the generator operating parameters; S105 calculates the distance between the center of the 100% equal active impedance circle and other impedance circles; S106 calculates the intersection area of ​​the 100% equal active impedance circle and other impedance circles according to the distance between the centers of the circles; S107 selects a stator impedance criterion according to the intersection area.

[0026] Generator operating parameters include: Generator capacity, generator longitudinal axis synchronous reactance, generator longitudinal axis transient reactance, generator transverse axis synchronous reactance and generator power factor, among which the generator longitudinal axis synchronous reactance, generator longitudinal axis transient reactance and generator transverse axis synchronous reactance are all unsaturated values; The main transformer operating parameters include: Main transformer capacity and main transformer short-circuit impedance; Power system operating parameters include: The power system benchmark capacity and the power system minimum mode positive sequence impedance.

[0027] The specific steps for calculating the per unit value of the connection reactance between the generator and the power system based on the operating parameters of the generator, main transformer and power system are: Calculate the short-circuit impedance of the main transformer to the rated capacity of the generator: Calculate the minimum positive sequence impedance of the power system to the rated capacity of the generator; Calculate the per unit value of the connection reactance between the generator and the system, and add the short-circuit impedance of the main transformer calculated to the rated capacity of the generator and the minimum positive-sequence impedance of the power system calculated to the rated capacity of the generator.

[0028] The specific steps for calculating the impedance circle that intersects with the 100% equal active impedance circle according to the generator operating parameters are: The intersection point of the impedance circle and the 100% equal active impedance circle is obtained according to the synchronous reactance of the generator longitudinal axis and the transient reactance of the generator longitudinal axis, and the center and position of the impedance circle are determined according to the intersection point.

[0029] The specific steps for calculating the 100% equal active impedance circle based on the generator operating parameters and the per unit value of the connection reactance between the generator and the power system are as follows: The ordinate of the 100% equal active impedance circle is determined according to the per unit value of the connection reactance between the generator and the power system, and the abscissa and radius of the 100% equal active impedance circle are determined according to the operating parameters of the generator.

[0030] Other impedance circles include the asynchronous boundary impedance circle, the static stability limit impedance circle of thermal power units and the static stability limit impedance circle of hydropower units.

[0031] The specific steps for selecting the stator impedance criterion based on the intersection area are: If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is smaller than the intersection area of ​​the thermal power unit static stability limit impedance circle and the 100% equal active impedance circle, the stator impedance criterion selects the thermal power unit static stability limit impedance circle; If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is larger than the intersection area of ​​the static stability limit impedance circle of the thermal power unit and the 100% equal active impedance circle, the asynchronous boundary impedance circle is selected as the stator impedance criterion; If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is smaller than the intersection area of ​​the hydropower unit static stability limit impedance circle and the 100% equal active impedance circle, the stator impedance criterion selects the hydropower unit static stability limit impedance circle; If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is larger than the intersection area of ​​the static stability limit impedance circle of the hydropower unit and the 100% equal active impedance circle, the asynchronous boundary impedance circle is selected as the stator impedance criterion.

[0032] Another embodiment of the present invention provides a method for calibrating the impedance circle of a generator demagnetization protection. Choosing the asynchronous boundary impedance circle or the static limit impedance circle will directly affect the sensitivity of the demagnetization protection. Generally, the static limit impedance circle can capture the signal of insufficient generator excitation earlier, but it may also cause false protection; while the asynchronous boundary impedance circle is relatively conservative, but in some cases it may not trigger the protection in time.

[0033] Low excitation limitation is another protection measure to prevent generator demagnetization. It avoids demagnetization by limiting the lower limit of the excitation current of the generator. The coordination between demagnetization protection and low excitation limitation is crucial. The two need to be coordinated with each other to prevent false protection and ensure that the fault can be removed in time and effectively when demagnetization occurs. Due to the particularity of hydropower units, the verification of this coordination relationship becomes more complicated, and it is necessary to comprehensively consider multiple factors such as the electrical characteristics of the unit, operating conditions, and performance of the protection device.

[0034] We have developed a demagnetization protection impedance circle calibration system. Based on the setting calculation of relay protection for equipment in the plant, we have developed a system that is in line with actual working conditions, has powerful functions, flexible applications, and has integrated functions such as set value calibration. There is no need for a complicated modeling process. You only need to manually input the equivalent impedance parameters of the power grid and the plant equipment parameters. The system automatically matches the model algorithm and automatically performs demagnetization protection impedance circle calibration. This system not only meets the needs of set value calibration of power plants, but also meets the needs of current digital construction.

[0035] 1. First set the rated capacity of the generator as the base capacity. , and then set the rated voltage of the generator as the reference voltage, .

[0036] 2. Enter the generator capacity (MVA) "Vertical axis synchronous reactance (unsaturated value) "Vertical axis transient reactance (unsaturated value) "Horizontal axis synchronous reactance (unsaturated value) "Power Factor ”.

[0037] 3. Input "Main transformer capacity (MVA) "Short circuit impedance ”; 4. Enter the system base capacity (MVA) "Minimum positive sequence impedance ”.

[0038] 5. Calculate the short-circuit impedance of the main transformer to the rated capacity of the generator. .

[0039] 6. Calculate the system minimum positive sequence impedance to the rated capacity of the generator. .

[0040] 7. Calculate the per unit value of the connection reactance (including the step-up transformer impedance) between the generator and the system (with the rated value of the generator as the base value), that is, the per unit value of the equivalent reactance of the system converted to the generator bus under the minimum operating mode, .

[0041] 8. Calculate the center of the 100% equal active impedance circle as ( , ), the radius is .in , , , so it can be simplified to the circle center is ( , ), the radius is ,like Figure 2 As shown in circle 3.

[0042] 9. Calculate the two points where the asynchronous boundary impedance circle intersects the impedance plane jx axis and , , , then the center of the asynchronous boundary impedance circle is (0, ), the radius is ,like Figure 2 As shown in circle 1.

[0043] 10. Calculate the two points where the static stability limit impedance circle (thermal power unit) intersects with the impedance plane jx axis and , , , then the center of the static limit impedance circle is (0, ), the radius is ,like Figure 2 As shown in circle 2.

[0044] 11. Calculate the two points where the static stability limit impedance circle (hydropower unit) intersects with the impedance plane jx axis and , , , then the center of the static limit impedance circle is (0, ), the radius is ,like Figure 3 Shown 12. Calculate the distance between the center of the 100% equal active power circle and the center of the asynchronous circle .

[0045] 13. Calculate the distance between the center of the 100% equal active power circle and the center of the static stable power circle (thermal power) .

[0046] 14. Calculate the distance between the center of the 100% equal active power circle and the center of the static stable circle (hydropower) .

[0047] 15. Calculate the intersection area of ​​the 100% equal active impedance circle and the asynchronous circle , , intersection area .

[0048] 16. Calculate the intersection area of ​​the 100% equal active impedance circle and the static stability circle (thermal power) , , intersection area .

[0049] 17. Calculate the intersection area of ​​the 100% equal active impedance circle and the static stability circle (hydropower) , , intersection area .

[0050] 18. For thermal power units, That is, the intersection area of ​​the 100% equal active impedance circle and the asynchronous boundary impedance circle on the impedance plane is smaller than that of the statically stable limit impedance circle, which proves that the 100% equal active impedance circle and the asynchronous boundary impedance circle intersect very little or not at all on the impedance plane, but intersects deeply with the statically stable limit impedance circle. In order to detect demagnetization faults earlier, the statically stable limit impedance circle should be selected as the stator impedance criterion.

[0051] 19. For thermal power units, That is, the intersection area of ​​the 100% equal active impedance circle and the asynchronous boundary impedance circle on the impedance plane is larger than that of the static limit impedance circle, which proves that the 100% equal active impedance circle, the static limit impedance circle and the asynchronous boundary impedance circle all intersect and intersect deeply on the impedance plane, and all can detect demagnetization faults earlier. Therefore, the asynchronous boundary impedance circle should be selected as the stator impedance criterion.

[0052] 20. For hydropower units, That is, the intersection area of ​​the 100% equal active impedance circle and the asynchronous boundary impedance circle on the impedance plane is smaller than that of the statically stable limit impedance circle, which proves that the 100% equal active impedance circle and the asynchronous boundary impedance circle intersect very little or not at all on the impedance plane, but intersects deeply with the statically stable limit impedance circle. In order to detect demagnetization faults earlier, the statically stable limit impedance circle should be selected as the stator impedance criterion.

[0053] 21. For hydropower units, That is, the intersection area of ​​the 100% equal active impedance circle and the asynchronous boundary impedance circle on the impedance plane is larger than that of the static limit impedance circle, which proves that the 100% equal active impedance circle, the static limit impedance circle and the asynchronous boundary impedance circle all intersect and intersect deeply on the impedance plane, and all can detect demagnetization faults earlier. Therefore, the asynchronous boundary impedance circle should be selected as the stator impedance criterion.

[0054] like Figure 4 As shown, another embodiment of the present invention provides a generator demagnetization protection impedance circle calibration system, comprising: Parameter acquisition module: used to obtain the operating parameters of the generator, main transformer and power system; The first calculation module is used to calculate the per unit value of the connection reactance between the generator and the power system according to the working parameters of the generator, the main transformer and the power system; The second calculation module is used to calculate the 100% equal active impedance circle according to the generator working parameters and the per unit value of the connection reactance between the generator and the power system; The third calculation module is used to calculate other impedance circles that intersect with the 100% equal active impedance circle according to the generator operating parameters; The fourth calculation module is used to calculate the center distance between the 100% equal active impedance circle and other impedance circles; Intersection area calculation module: used to calculate the intersection area of ​​100% equal active impedance circle and other impedance circles according to the distance between the centers of the circles; Selection module: used to select the stator impedance criterion based on the intersection area.

[0055] A terminal device is provided in one embodiment of the present invention. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned method embodiments are implemented. Alternatively, when the processor executes the computer program, the functions of the modules / units in the above-mentioned device embodiments are implemented.

[0056] The computer program may be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to accomplish the present invention.

[0057] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0058] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0059] The memory may be used to store the computer programs and / or modules, and the processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory.

[0060] If the module / unit integrated in the terminal device is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above-mentioned various method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0061] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields, and the above-mentioned specific embodiments are only illustrative and instructive, rather than restrictive. Under the guidance of the specification, a person skilled in the art can make many forms without departing from the scope of protection of the claims of the present invention, all of which belong to the scope of protection of the present invention.

Claims

1. A method for verifying the impedance circle of a generator demagnetization protection, characterized in that: include: Obtain operating parameters of generators, main transformers and power systems; Calculate the per unit value of the connection reactance between the generator and the power system based on the operating parameters of the generator, main transformer and power system; Calculate the 100% equal active impedance circle based on the generator operating parameters and the per unit value of the connection reactance between the generator and the power system; Calculate other impedance circles that intersect with the 100% equal active impedance circle based on the generator operating parameters; Calculate the distance between the center of the 100% equal active impedance circle and other impedance circles; Calculate the intersection area of ​​the 100% equal active impedance circle and other impedance circles based on the distance between the circle centers; The stator impedance criterion is selected based on the intersection area.

2. A generator demagnetization protection impedance circle calibration method according to claim 1, characterized in that: Generator operating parameters include: Generator capacity, generator longitudinal axis synchronous reactance, generator longitudinal axis transient reactance, generator transverse axis synchronous reactance and generator power factor, among which the generator longitudinal axis synchronous reactance, generator longitudinal axis transient reactance and generator transverse axis synchronous reactance are all unsaturated values; The main transformer operating parameters include: Main transformer capacity and main transformer short-circuit impedance; Power system operating parameters include: The power system benchmark capacity and the power system minimum mode positive sequence impedance.

3. A generator demagnetization protection impedance circle calibration method according to claim 2, characterized in that: The specific steps for calculating the per unit value of the connection reactance between the generator and the power system based on the operating parameters of the generator, main transformer and power system are: Calculate the short-circuit impedance of the main transformer to the rated capacity of the generator: Calculate the minimum positive sequence impedance of the power system to the rated capacity of the generator; Calculate the per unit value of the connection reactance between the generator and the system, and add the short-circuit impedance of the main transformer calculated to the rated capacity of the generator and the minimum positive-sequence impedance of the power system calculated to the rated capacity of the generator.

4. A generator demagnetization protection impedance circle calibration method according to claim 2, characterized in that: The specific steps for calculating the impedance circle that intersects with the 100% equal active impedance circle according to the generator operating parameters are: The intersection point of the impedance circle and the 100% equal active impedance circle is obtained according to the synchronous reactance of the generator longitudinal axis and the transient reactance of the generator longitudinal axis, and the center and position of the impedance circle are determined according to the intersection point.

5. The method for calibrating the impedance circle of a generator demagnetization protection according to claim 1, characterized in that: The specific steps for calculating the 100% equal active impedance circle based on the generator operating parameters and the per unit value of the connection reactance between the generator and the power system are as follows: The ordinate of the 100% equal active impedance circle is determined according to the per unit value of the connection reactance between the generator and the power system, and the abscissa and radius of the 100% equal active impedance circle are determined according to the operating parameters of the generator.

6. A generator demagnetization protection impedance circle calibration method according to claim 1, characterized in that: Other impedance circles include the asynchronous boundary impedance circle, the static stability limit impedance circle of thermal power units and the static stability limit impedance circle of hydropower units.

7. A generator demagnetization protection impedance circle calibration method according to claim 6, characterized in that: The specific steps for selecting the stator impedance criterion based on the intersection area are: If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is smaller than the intersection area of ​​the thermal power unit static stability limit impedance circle and the 100% equal active impedance circle, the stator impedance criterion selects the thermal power unit static stability limit impedance circle; If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is larger than the intersection area of ​​the static stability limit impedance circle of the thermal power unit and the 100% equal active impedance circle, the asynchronous boundary impedance circle is selected as the stator impedance criterion; If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is smaller than the intersection area of ​​the hydropower unit static stability limit impedance circle and the 100% equal active impedance circle, the stator impedance criterion selects the hydropower unit static stability limit impedance circle; If the intersection area of ​​the asynchronous boundary impedance circle and the 100% equal active impedance circle is larger than the intersection area of ​​the static stability limit impedance circle of the hydropower unit and the 100% equal active impedance circle, the asynchronous boundary impedance circle is selected as the stator impedance criterion.

8. A generator demagnetization protection impedance circle calibration system, characterized in that: include: Parameter acquisition module: used to obtain the operating parameters of the generator, main transformer and power system; The first calculation module is used to calculate the per unit value of the connection reactance between the generator and the power system according to the working parameters of the generator, the main transformer and the power system; The second calculation module is used to calculate the 100% equal active impedance circle according to the generator working parameters and the per unit value of the connection reactance between the generator and the power system; The third calculation module is used to calculate other impedance circles that intersect with the 100% equal active impedance circle according to the generator operating parameters; The fourth calculation module is used to calculate the center distance between the 100% equal active impedance circle and other impedance circles; Intersection area calculation module: used to calculate the intersection area of ​​100% equal active impedance circle and other impedance circles according to the distance between the centers of the circles; Selection module: used to select the stator impedance criterion based on the intersection area.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the generator demagnetization protection impedance circle calibration method as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of a generator demagnetization protection impedance circle calibration method as described in any one of claims 1 to 7 are implemented.

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