Reclosing locking setting method and system considering dynamic stability of transformer

Abstract

The invention discloses a reclosing locking setting method and system considering transformer dynamic stability, and relates to the technical field of power transformer dynamic stability assessment, and the method comprises the steps: building a short-circuit current calculation model, and calculating a steady-state current amplitude and a transformer short-circuit impact current; establishing a transformer model, and calculating the radial force and the axial force of a wire cake; performing function fitting on the obtained data to obtain a corresponding function relationship; and calculating a check stress value, and carrying out reclosing locking detection action based on a reclosing locking criterion. According to the method, whether reclosing locking needs to be carried out or not can be more accurately judged by calculating the stress of the transformer under the short-circuit impact; through the self-defined correction coefficient, various factors are considered, the state of the transformer can be evaluated more comprehensively, and the safety is improved; the method has better effects in the aspects of judging whether reclosing endanger the dynamic stability of the transformer or not, evaluating the state of the transformer and judging reclosing locking.

Description

Technical Field

[0001] The invention relates to the technical field of dynamic stability assessment of power transformers, and in particular to a reclosing lock setting method and system taking into account the dynamic stability of transformers. Background Art

[0002] The current method adopted by the power system to avoid the instability of transformer dynamic stability is to conduct short-circuit dynamic stability verification at the factory. The object of this type of verification is a new transformer that has just left the factory and has not been put into operation. However, for transformers in actual operation, they often experience long-term operation, which causes certain changes in their mechanical properties.

[0003] Taking into account the dynamic stability margin of the transformer will decrease due to two short-circuit shocks in a short period of time under short-circuit reclosing conditions. The long service life of the transformer will also lead to a decline in material parameter performance. At the same time, due to the influence of factors such as the transformer having undergone multiple overhauls resulting in a decrease in the strength of fixed devices and the transformer having experienced multiple short-circuit shocks resulting in the accumulation of deformation, the dynamic stability of the transformer winding under permanent fault conditions under reclosing often becomes unstable.

[0004] Moreover, after the initial short circuit occurs, the fault line is cut off and the transformer runs on other loads through the busbar. From the factors affecting the short-circuit current, it can be seen that if the load is light or no-load at this time, the short-circuit impact current value after reclosing will be greater than the initial short-circuit current value, further threatening the dynamic stability of the transformer under reclosing.

[0005] Therefore, the short-circuit impact current under the reclosing switch is predicted and the corresponding transformer winding stress value is calculated based on the predicted value. This stress value is checked. If it can be determined whether the possible stress value of the reclosing switch on the permanent fault transformer exceeds the corresponding stress limit value, it can be determined whether the reclosing switch endangers the dynamic stability of the transformer. If it endangers the dynamic stability, the reclosing switch should be locked and the fault should be eliminated by the operating personnel. If it does not endanger the dynamic stability, the reclosing switch should be carried out to improve the power supply reliability of the power system. Summary of the invention

[0006] In view of the above-mentioned problems, the present invention is proposed.

[0007] Therefore, the technical problem solved by the present invention is that the setting of the reclosing switch by the traditional relay protection system does not take into account the dynamic stability instability of the transformer after it is subjected to two short-circuit shocks in a short period of time, and how to solve the problem of more accurate reclosing switch lockout judgment.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: a reclosing lock setting method taking into account the dynamic stability of the transformer, comprising establishing a short-circuit current calculation model, calculating the steady-state current amplitude and the transformer short-circuit impact current; establishing a transformer model, calculating the radial force and axial force of the coil; performing function fitting on the obtained data to obtain the corresponding function relationship; calculating and checking the stress value, and based on the reclosing lock criterion, the reclosing lock detection action.

[0009] As a preferred solution of the reclosing lock setting method taking into account the dynamic stability of the transformer described in the present invention, wherein: the calculation of the steady-state current amplitude and the transformer short-circuit impact current includes, according to the collected transformer parameters, establishing a short-circuit current calculation model of the power system containing the transformer; setting the line load rate to multiple values ​​between 10% and 100%, and recording the steady-state current amplitude under the current load rate. And the short-circuit impact current of three-phase short-circuit to ground at the corresponding load rate n represents the corresponding load rate number.

[0010] As a preferred solution of the reclosing lock setting method taking into account the dynamic stability of the transformer described in the present invention, the transformer parameters include transformer geometric parameters, transformer structural parameters, and transformer line parameters.

[0011] As a preferred solution of the reclosing lock setting method taking into account the dynamic stability of the transformer described in the present invention, wherein: the calculation of the radial force and axial force of the coil includes: constructing a transformer finite element model based on the geometric parameters and structural parameters of the transformer; using the short-circuit current calculated value as the excitation of the transformer finite element model, calculating the radial force F of each turn of the transformer winding under the action of the short-circuit impulse current at different load rates r ni With axial force F a ni , i represents the winding number.

[0012] As a preferred solution of the reclosing lock setting method taking into account the dynamic stability of the transformer described in the present invention, wherein: the corresponding functional relationship includes the functional relationship between the radial force, the axial force and the short-circuit impulse current, and the functional relationship between the short-circuit impulse current and the steady-state current amplitude under different load rates and the initial phase angle of the power supply; the obtained data includes the short-circuit impulse current and the data of the radial force and axial force of each coil, and the data of the short-circuit impulse current and the steady-state current under different load rates and the initial phase angle of the power supply; the radial force and axial force data of each coil obtained are used as dependent variables, and the short-circuit impulse current is used as an independent variable, and function fitting is performed through a multi-layer perceptron, and the fitted functional relationship between the radial force, axial force and the short-circuit impulse current is expressed as:

[0013]

[0014] The obtained short-circuit impulse current is used as the dependent variable, and the steady-state current amplitude under different load rates is used as the independent variable. Function fitting is performed through a multi-layer perceptron. The functional relationship between the short-circuit impulse current after fitting, the steady-state current amplitude under different load rates, and the initial phase angle of the power supply is expressed as:

[0015]

[0016] The distance protection of the relay protection system determines the distance to the fault point. If the transformer outlet is short-circuited, the next step of reclosing lockout determination is performed. Otherwise, the reclosing lockout determination is not performed. Based on the transformer outlet short-circuit, the short-circuit impact current under the initial short-circuit impact is read. The radial force of the initial short circuit is calculated based on the fitting functions f and g. and axial force Based on the transformer output short circuit, read the steady-state current value before the reclosing short circuit impact And the maximum reclosing short-circuit impact current is calculated based on the fitting function h The radial force of the reclosing short circuit is calculated based on the fitting functions f and g. and axial force

[0017] As a preferred solution of the reclosing lock setting method taking into account the dynamic stability of the transformer described in the present invention, the check stress value includes the average annular stress σ t1 , radial bending stress σ br , axial compressive stress σ act , axial bending stress σ ba ; Calculate the average annular stress σ t1 , expressed as:

[0018]

[0019] Among them, A cu Represents the cross-sectional area of ​​the winding conductor; calculates the radial bending stress σ br , expressed as:

[0020]

[0021] Among them, F r It represents the radial force on the coil conductor, Δ represents the radial displacement of the conductor, and the maximum allowable value is 1.5mm. v represents the radial thickness of a single ordinary wire, I0 represents the polar moment of inertia, n b Indicates the number of windings connected in parallel radially, n t Indicates the number of windings connected in parallel axially, w vIndicates the width of a single ordinary conductor or transposed conductor (along the winding axis); calculates the axial compressive stress σ act , expressed as:

[0022]

[0023] Among them, F a Indicates the inter-segment axial force or winding axial force, A z Indicates the effective area of ​​the spacer, paper insulation, end ring or pressure plate, σ act Indicates the axial compressive stress of the pad, paper insulation, end ring or pressure plate; calculates the axial bending stress σ ba , expressed as:

[0024]

[0025] Among them, Δ' represents the axial displacement of the conductor, and the maximum allowable value is 3mm.

[0026] As a preferred solution of the reclosing lock setting method considering the dynamic stability of the transformer described in the present invention, the reclosing lock criterion includes: according to the radial force of the initial short circuit Axial force and radial force of short circuit reclosing Axial force The average annular stress, radial bending stress, axial compression stress, and axial bending stress are calculated to obtain the initial short-circuit stress array σ1 and the reclosing short-circuit stress array σ2, which are expressed as:

[0027] σ1=[σ t1 , σ br1 , σ act1 , σ ba1 ]

[0028] σ2=[σ t2 , σ br2 , σ act2 , σ ba2 ]

[0029] The specified limit values ​​corresponding to the mean annular stress, radial bending stress, axial compression stress, and axial bending stress include the mean annular stress limit value σ t1_cr , radial bending stress limit value σ br_cr , axial compressive stress limit value σ act_cr , axial bending stress limit value σ ba_cr; According to the working conditions, the average annular stress limit value, radial bending stress limit value, axial compression stress limit value, and axial bending stress limit value are set with custom correction coefficients k1, k2, k3, and k4 respectively under the short-circuit impact of the reclosing switch. Considering the relationship between the value of the stress array σ1 and the limit value of the initial short circuit, the transformer's operating years, the number of overhauls, the number of short-circuit impacts after the last replacement of windings and fixed components, and the cumulative effect, the corrected average annular stress limit value, radial bending stress limit value, axial compression stress limit value, and axial bending stress limit value are set to the relay protection equipment to judge the stress under the short-circuit impact of the reclosing switch; suppose the stress limit value array is expressed as:

[0030]

[0031] Assume the correction coefficient array, expressed as:

[0032] k = [k1, k2, k3, k4]

[0033] when When , the reclosing switch will not be locked, otherwise the locking reclosing switch will be started as long as any one of the elements is not satisfied.

[0034] Another object of the present invention is to provide a reclosing lock setting system taking into account the dynamic stability of the transformer, which can determine whether the reclosing is locked by predicting the magnitude of the short-circuit impact current under the reclosing, thereby solving the problem of dynamic stability instability after the transformer short-circuit impact.

[0035] As a preferred solution of the reclosing lock setting system taking into account the dynamic stability of the transformer described in the present invention, it includes: a current calculation module, a force calculation module, a function fitting module, and a detection action module; the current calculation module is used to establish a short-circuit current calculation model, calculate the steady-state current amplitude and the transformer short-circuit impact current; the force calculation module is used to establish a transformer model, calculate the radial force and axial force of the coil; the function fitting module is used to perform function fitting on the obtained data to obtain the corresponding function relationship; the detection action module is used to calculate the verification stress value, and based on the reclosing lock criterion, the reclosing lock detection action.

[0036] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of a reclosing lock setting method taking into account the dynamic stability of a transformer.

[0037] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a reclosing lockout setting method taking into account the dynamic stability of a transformer.

[0038] Beneficial effects of the present invention: The reclosing lock setting method taking into account the dynamic stability of the transformer provided by the present invention calculates the stress of the transformer under short-circuit impact and compares it with the preset limit value, so as to more accurately determine whether reclosing lock is needed to avoid transformer instability caused by reclosing; by setting a custom correction coefficient, factors such as the transformer's operating years, the number of overhauls, and the number of short-circuit impacts can be considered to more comprehensively evaluate the transformer status and improve safety; through accurate reclosing lock judgment, the probability of false lock and missed lock can be reduced, thereby improving the reliability of the system; the present invention achieves better results in determining whether the reclosing endangers the dynamic stability of the transformer, evaluating the transformer status, and judging the reclosing lock. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0040] Figure 1 An overall flow chart of a reclosing lockout setting method taking into account transformer dynamic stability is provided for the first embodiment of the present invention.

[0041] Figure 2 A short-circuit current calculation model diagram of a reclosing lockout setting method taking into account the dynamic stability of a transformer provided in the first embodiment of the present invention.

[0042] Figure 3 A transformer finite element model diagram of a reclosing lockout setting method taking into account the dynamic stability of the transformer provided in the first embodiment of the present invention.

[0043] Figure 4 A low voltage winding short-circuit current diagram of a reclosing lockout setting method taking into account the dynamic stability of a transformer is provided in accordance with a second embodiment of the present invention.

[0044] Figure 5 The third embodiment of the present invention provides an overall flow chart of a reclosing lock setting system taking into account the dynamic stability of the transformer. DETAILED DESCRIPTION

[0045] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0046] Example 1, reference Figure 1-Figure 3 , which is an embodiment of the present invention, provides a reclosing lock setting method taking into account the dynamic stability of the transformer, comprising:

[0047] S1: Establish a short-circuit current calculation model to calculate the steady-state current amplitude and the transformer short-circuit impact current.

[0048] Furthermore, the calculation of the steady-state current amplitude and the transformer short-circuit impact current includes: establishing a short-circuit current calculation model for the power system including the transformer according to the collected transformer parameters; setting the line load rate to multiple values ​​between 10% and 100%, and recording the steady-state current amplitude under the current load rate And the short-circuit impact current of three-phase short-circuit to ground at the corresponding load rate n represents the corresponding load rate number.

[0049] It should be noted that the short-circuit current calculation model of the power system including transformer is established as follows: Figure 2 As shown in the figure, the model adopts the operating condition that the high-voltage winding and the medium-voltage winding are powered by an infinite system, the medium-voltage side is a small-capacity power supply, and the low-voltage side is a winding without power supply. In order to obtain the maximum possible short-circuit impact current and ensure that the reclosing short-circuit impact current value i rec ≥Corrected short-circuit impulse current limit value i cr ,make and Close to 90°, set the load to a pure inductive charge, regard the 110KV voltage source as an ideal voltage source, set the 35KV voltage source X / R ratio to 90, regard the circuit breaker as an ideal circuit breaker and set the circuit breaker resistance to 0.

[0050] S2: Establish a transformer model and calculate the radial force and axial force of the coil.

[0051] Furthermore, the calculation of the steady-state current amplitude and the transformer short-circuit impact current includes: establishing a short-circuit current calculation model for the power system including the transformer according to the collected transformer parameters; setting the line load rate to multiple values ​​between 10% and 100%, and recording the steady-state current amplitude under the current load rate And the short-circuit impact current of three-phase short-circuit to ground at the corresponding load rate n represents the corresponding load rate number.

[0052] It should be noted that transformer parameters include transformer geometric parameters, transformer structural parameters, and transformer line parameters.

[0053] It should also be noted that the calculation of the radial force and axial force of the coil includes constructing a transformer finite element model based on the transformer geometric parameters and structural parameters under ANSYS Maxwell, such as Figure 3 As shown in the figure, the short-circuit current calculated value is used as the excitation of the transformer finite element model to calculate the radial force F of each winding of the transformer under the short-circuit impulse current of different load rates. r ni With axial force F a ni , i represents the winding number.

[0054] S3: Perform function fitting on the acquired data to obtain the corresponding functional relationship.

[0055] Furthermore, the corresponding functional relationships include the functional relationship between radial force, axial force and short-circuit impulse current, and the functional relationship between short-circuit impulse current and the steady-state current amplitude running under different load rates and the initial phase angle of the power supply; the data obtained include the data of short-circuit impulse current and the radial force and axial force of each coil, and the data of short-circuit impulse current and the steady-state current running under different load rates and the initial phase angle of the power supply.

[0056] It should be noted that the radial force and axial force data of each coil are taken as dependent variables, and the short-circuit impulse current is taken as the independent variable. The function is fitted by a multi-layer perceptron. The functional relationship between the fitted radial force, axial force and short-circuit impulse current is expressed as:

[0057]

[0058] The obtained short-circuit impulse current is used as the dependent variable, and the steady-state current amplitude under different load rates is used as the independent variable. Function fitting is performed through a multi-layer perceptron. The functional relationship between the short-circuit impulse current after fitting, the steady-state current amplitude under different load rates, and the initial phase angle of the power supply is expressed as:

[0059]

[0060] It should also be noted that the distance protection of the relay protection system determines the distance to the fault point. If the transformer outlet is short-circuited, the next step of reclosing lockout judgment is carried out, otherwise the reclosing lockout judgment is not carried out; based on the transformer outlet short-circuit, the short-circuit impact current under the initial short-circuit impact is read The radial force of the initial short circuit is calculated based on the fitting functions f and g. and axial force Based on the transformer output short circuit, read the steady-state current value before the reclosing short circuit impact And the maximum reclosing short-circuit impact current is calculated based on the fitting function h The radial force of the reclosing short circuit is calculated based on the fitting functions f and g. and axial force

[0061] S4: Calculate and check the stress value, and based on the reclosing lock criterion, perform the reclosing lock detection action.

[0062] Furthermore, the stress values ​​to be checked include the mean annular stress σ t1 , radial bending stress σ br , axial compressive stress σ act , axial bending stress σ ba ; Calculate the average annular stress σ t1 , expressed as:

[0063]

[0064] Among them, A cu Represents the cross-sectional area of ​​the winding conductor; calculates the radial bending stress σ br , expressed as:

[0065]

[0066] Among them, F r It represents the radial force on the coil conductor, Δ represents the radial displacement of the conductor, and the maximum allowable value is 1.5mm. v represents the radial thickness of a single ordinary wire, I0 represents the polar moment of inertia, n b Indicates the number of windings connected in parallel radially, n t Indicates the number of windings connected in parallel axially, w v Indicates the width of a single ordinary conductor or transposed conductor (along the winding axis); calculates the axial compressive stress σ act , expressed as:

[0067]

[0068] Among them, F a Indicates the inter-segment axial force or winding axial force, A z Indicates the effective area of ​​the spacer, paper insulation, end ring or pressure plate, σ act Indicates the axial compressive stress of the pad, paper insulation, end ring or pressure plate; calculates the axial bending stress σ ba , expressed as:

[0069]

[0070] Wherein, Δ' represents the axial displacement of the conductor, and the maximum allowable value is 3mm.

[0071] It should be noted that the reclosing lock criterion includes the radial force of the initial short circuit. Axial force and radial force of short circuit reclosing Axial force The average annular stress, radial bending stress, axial compression stress, and axial bending stress are calculated to obtain the initial short-circuit stress array σ1 and the reclosing short-circuit stress array σ2, which are expressed as:

[0072] σ1=[σ t1 , σ br1 , σ act1 , σ ba1 ]

[0073] σ2=[σ t2 , σ br2 , σ act2 , σ ba2 ]

[0074] The specified limit values ​​corresponding to the mean annular stress, radial bending stress, axial compression stress, and axial bending stress include the mean annular stress limit value σ t1_cr , radial bending stress limit value σ br_cr , axial compressive stress limit value σ act_cr , axial bending stress limit value σ ba_cr ; According to the working conditions, the average annular stress limit value, radial bending stress limit value, axial compression stress limit value, and axial bending stress limit value are set with custom correction coefficients k1, k2, k3, and k4 respectively under the short-circuit impact of the reclosing switch. Considering the relationship between the value of the stress array σ1 and the limit value of the initial short circuit, the transformer's operating years, the number of overhauls, the number of short-circuit impacts after the last replacement of windings and fixed components, and the cumulative effect, the corrected average annular stress limit value, radial bending stress limit value, axial compression stress limit value, and axial bending stress limit value are set to the relay protection equipment to judge the stress under the short-circuit impact of the reclosing switch; suppose the stress limit value array is expressed as:

[0075]

[0076] Assume the correction coefficient array, expressed as:

[0077] k = [k1, k2, k3, k4]

[0078] when When , the reclosing switch will not be locked, otherwise the locking reclosing switch will be started as long as any one of the elements is not satisfied.

[0079] It should also be noted that user-defined corrections include user-defined corrections based on the radial and axial stress judgment standards taking into account the aging of the transformer and the cumulative effects of the reclosing switch, and using the fitted functional relationship between the radial force, axial force and the short-circuit impulse current to inversely solve the corresponding corrected short-circuit impulse current limit value, and then using the line's measuring elements to obtain real-time steady-state current data, and using the functional relationship between the short-circuit impulse current and the steady-state current operating at different load rates to calculate the reclosing short-circuit impulse current value.

[0080] It should also be noted that, considering the reliability of system operation, when the system fault type is a three-phase short circuit to ground on the low-voltage side, the reclosing lock detection action is activated. The reclosing lock judgment criterion is: the reclosing short-circuit impulse current value i rec ≥Corrected short-circuit impulse current limit value i cr .

[0081] It should also be noted that the limit values ​​corresponding to the average annular stress, radial bending stress, axial compression stress, and axial bending stress are as shown in Table 1 below:

[0082] Table 1 Limit value regulations corresponding to four stress values

[0083]

[0084]

[0085] Example 2, reference Figure 4 As an embodiment of the present invention, a reclosing lock setting method taking into account the dynamic stability of the transformer is provided. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0086] Firstly, the geometric parameters, structural parameters and line parameters of the transformer are collected, and a MATLAB Simulink short-circuit current calculation model is established. A set of working conditions when the line load factor is designed as the initial short circuit, the load factor is 100%, the line is unloaded before reclosing, and the load factor is 0% are used as examples for verification.

[0087] Secondly, the obtained data is fitted with a multi-layer perceptron MLP to obtain three fitting function expressions of f, g, and h, and read the short-circuit impact current under the initial short-circuit impact. And directly calculate the radial force of the initial short circuit based on the fitting functions f and g and axial force Taking this example as an example, the short-circuit impulse current under the first short-circuit impulse is The value is 29934A, and The maximum values ​​are 87059.49N and 89678.78N; read the steady-state current before the reclosing short-circuit impact The value is 0A, and the maximum possible reclosing short-circuit impact current is calculated according to the fitting function h The value is 31792A, and the radial force of the reclosing short circuit is calculated based on the fitting functions f and g. and axial force The maximum values ​​are 97999.07N and 100811.2N.

[0088] Finally, the initial short-circuit stress array, reclosing short-circuit stress array, and stress limit value array are calculated as σ1 = [31.43, 31.77, 6.94, 21.36], σ2 = [35.38, 35.76, 7.80, 24.02], and σ cr =[49, 126, 35, 126], refer to the calculation results of array σ1, consider the recent transformer preventive test report, consider the operating life of 20 years, take into account the cumulative effect of reclosing, and take the correction coefficient array k = [0.9, 0.9, 0.95, 0.95].

[0089] Determine σ2=[35.38, 35.76, 7.80, 24.02]<σ cr ·k=[46.55,119.7,31.5,119.7] The inequality holds, so the reclosing switch should be allowed not to be locked.

[0090] In addition, in this process, this example calculates the maximum possible reclosing short-circuit impact current according to the fitting function h The value is 31792A, and Figure 4 The simulation model calculates the maximum possible reclosing short-circuit impact current value to be 31781A, a difference of 11A. This shows that our invention has a more accurate reclosing lockout judgment.

[0091] Example 3, reference Figure 5 , which is an embodiment of the present invention, provides a reclosing lock setting system taking into account the dynamic stability of the transformer, including a current calculation module, a force calculation module, a function fitting module, and a detection action module.

[0092] The current calculation module is used to establish a short-circuit current calculation model, calculate the steady-state current amplitude and the transformer short-circuit impact current; the force calculation module is used to establish a transformer model, calculate the radial force and axial force of the coil; the function fitting module is used to perform function fitting on the acquired data to obtain the corresponding functional relationship; the detection action module is used to calculate the verification stress value, and based on the reclosing lock criterion, the reclosing lock detection action.

[0093] If the function 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 technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0094] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0095] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0096] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc. It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and are not limited. Although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

[0097] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A reclosing lock setting method taking into account the dynamic stability of the transformer, characterized in that: include: Establish a short-circuit current calculation model to calculate the steady-state current amplitude and transformer short-circuit impact current; Establish transformer model and calculate radial force and axial force of coil; Perform function fitting on the acquired data to obtain the corresponding functional relationship; Calculate and check stress value, based on reclosing lock criteria, and perform reclosing lock detection action.

2. The reclosing lock setting method taking into account the dynamic stability of the transformer as claimed in claim 1, characterized in that: The calculation of the steady-state current amplitude and the transformer short-circuit impact current includes establishing a short-circuit current calculation model of the power system including the transformer according to the collected transformer parameters; Set the line load rate to multiple values ​​between 10% and 100%, and record the steady-state current amplitude at the current load rate And the short-circuit impact current of three-phase short-circuit to ground at the corresponding load rate n represents the corresponding load rate number.

3. The reclosing lock setting method taking into account the dynamic stability of the transformer as claimed in claim 2, characterized in that: The transformer parameters include transformer geometric parameters, transformer structural parameters, and transformer line parameters.

4. The reclosing lock setting method taking into account the dynamic stability of the transformer as claimed in claim 3 is characterized in that: The calculation of the radial force and the axial force of the coil comprises constructing a transformer finite element model based on the transformer geometric parameters and structural parameters; The short-circuit current calculated value is used as the excitation of the transformer finite element model to calculate the radial force F of each winding of the transformer under the short-circuit impulse current of different load rates. r ni With axial force i represents the winding number.

5. The reclosing lock setting method taking into account the dynamic stability of the transformer as claimed in claim 4 is characterized in that: The corresponding functional relationships include the functional relationships between radial force, axial force and short-circuit impulse current, and the functional relationships between short-circuit impulse current and steady-state current amplitude and initial phase angle of power supply under different load rates; The data obtained include short-circuit impulse current, radial force and axial force of each coil, short-circuit impulse current, steady-state current under different load rates and initial phase angle of power supply; The radial force and axial force data of each coil are taken as dependent variables, and the short-circuit impulse current is taken as the independent variable. The function is fitted by a multi-layer perceptron. The functional relationship between the radial force, axial force and short-circuit impulse current after fitting is expressed as: The obtained short-circuit impulse current is used as the dependent variable, and the steady-state current amplitude under different load rates is used as the independent variable. Function fitting is performed through a multi-layer perceptron. The functional relationship between the short-circuit impulse current after fitting, the steady-state current amplitude under different load rates, and the initial phase angle of the power supply is expressed as: The distance protection of the relay protection system determines the distance to the fault point. If the transformer outlet is short-circuited, the next step of reclosing lockout determination is performed. Otherwise, the reclosing lockout determination is not performed. Based on the transformer output short circuit, read the short circuit impact current under the initial short circuit impact The radial force of the initial short circuit is calculated based on the fitting functions f and g. and axial force Based on the transformer output short circuit, read the steady-state current value before the reclosing short circuit impact And the maximum reclosing short-circuit impact current is calculated based on the fitting function h And the radial force of the reclosing short circuit is calculated based on the fitting function numbers f and g and axial force 6. The reclosing lock setting method taking into account the dynamic stability of the transformer as claimed in claim 5, characterized in that: The check stress value includes the average annular stress σ t1 , radial bending stress σ br , axial compressive stress σ act , axial bending stress σ ba ; Calculate the mean annular stress σ t1 , expressed as: Among them, A cu Indicates the cross-sectional area of ​​the winding conductor; Calculation of radial bending stress σ br , expressed as: Among them, F r It represents the radial force on the coil conductor, Δ represents the radial displacement of the conductor, and the maximum allowable value is 1.5mm. v represents the radial thickness of a single ordinary wire, I0 represents the polar moment of inertia, n b Indicates the number of windings connected in parallel radially, n t Indicates the number of windings connected in parallel axially, w v Indicates the width of a single common conductor or transposed conductor (along the winding axis); Calculation of axial compressive stress σ act , expressed as: Among them, F a Indicates the inter-segment axial force or winding axial force, A z Indicates the effective area of ​​the spacer, paper insulation, end ring or pressure plate, σ act Indicates the axial compressive stress of the spacer, paper insulation, end ring or pressure plate; Calculation of axial bending stress σ ba , expressed as: Wherein, Δ' represents the axial displacement of the conductor, and the maximum allowable value is 3mm.

7. The reclosing lock setting method taking into account the dynamic stability of the transformer as claimed in claim 6, characterized in that: The reclosing lock criterion includes: Axial force and radial force of short circuit reclosing Axial force The average annular stress, radial bending stress, axial compression stress, and axial bending stress are calculated to obtain the initial short-circuit stress array σ1 and the reclosing short-circuit stress array σ2, which are expressed as: σ1=[σ t1 ,s br1 ,s act1 ,s ba1 ] σ2=[σ t2 ,s br2 ,s act2 ,s ba2 ] The specified limit values ​​corresponding to the mean annular stress, radial bending stress, axial compression stress, and axial bending stress include the mean annular stress limit value σ t1_cr , radial bending stress limit value σ br_cr , axial compressive stress limit value σ act_cr , axial bending stress limit value σ ba_cr ; According to the working conditions, the self-defined correction coefficients are set for the average annular stress limit value, radial bending stress limit value, axial compression stress limit value, and axial bending stress limit value under the short-circuit impact of the reclosing switch, which are k1, k2, k3, and k4 respectively. The relationship between the value of the stress array σ1 and the limit value of the initial short circuit, the transformer's operating years, the number of overhauls, the number of short-circuit impacts after the last replacement of windings and fixed parts, and the cumulative effect are comprehensively considered, and the corrected average annular stress limit value, radial bending stress limit value, axial compression stress limit value, and axial bending stress limit value are set to the relay protection equipment to judge the stress under the short-circuit impact of the reclosing switch; Assume the stress limit value array is expressed as: Assume the correction coefficient array, expressed as: k = [k1, k2, k3, k4] When σ2<σ cr k=[k1σ t1_cr , k2σ br_cr , k3σ act_cr , k4σ ba_cr ], the reclosing switch will not be locked, otherwise the reclosing switch will be locked as long as any one of the elements is not satisfied.

8. A system using the reclosing lock setting method taking into account the dynamic stability of the transformer as claimed in any one of claims 1 to 7, characterized in that: It includes current calculation module, force calculation module, function fitting module and action detection module; The current calculation module is used to establish a short-circuit current calculation model to calculate the steady-state current amplitude and the transformer short-circuit impact current; The radial force calculation module is used to establish a transformer model and calculate the radial force and axial force of the coil; The function fitting module is used to perform function fitting on the acquired data to obtain a corresponding function relationship; The detection action module is used to calculate the verification stress value and perform the reclosing lock detection action based on the reclosing lock criterion.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the reclosing lock setting method taking into account the dynamic stability of the transformer as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the reclosing lock setting method taking into account the dynamic stability of the transformer as described in any one of claims 1 to 7 are implemented.

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