Method for estimating residual magnetism of three-phase transformer, device for estimating residual magnetism of three-phase transformer, and electronic device

Abstract

The application provides a residual magnetism estimation method and device for a three-phase transformer and electronic equipment. The estimation method comprises: for any single-phase transformer in the three-phase transformer, obtaining the voltage amplitude U m , the angular frequency ω of the power supply and the primary-side coil turn number N1; calculating the residual magnetism amplitude Φ m according to the voltage amplitude U m and the angular frequency ω of the power supply in combination with formula (1); obtaining the voltage closing angle α, the opening-starting time t open and the opening-ending time t open + Δt of the single-phase transformer at no-load opening; and calculating the residual magnetism Φ r of the single-phase transformer after opening according to the residual magnetism amplitude Φ m , the voltage closing angle α, the opening-starting time t open and the opening-ending time t open + Δt in combination with formula (2). The application calculates the residual magnetism Φ r of the single-phase transformer after opening in combination with formula (2), thereby replacing the complex integral term containing U C , reducing the calculation difficulty, and optimizing the accuracy of the residual magnetism estimation method for the transformer.

Description

Technical Field

[0001] This application belongs to the field of transformer residual magnetism estimation technology, specifically relating to a method for estimating the residual magnetism of a three-phase transformer, as well as its estimation device and electronic equipment. Background Technology

[0002] The hysteresis effect of ferromagnetic materials often results in residual magnetism in transformers. When the transformer is switched on under no-load conditions, this residual magnetism accelerates core saturation, generating inrush currents that can reach 6-8 times the rated current, severely impacting the safe and stable operation of transformers, circuit breakers, and power systems. Accurate measurement and estimation of residual magnetism are crucial for avoiding the hazards of inrush currents, and scholars and professionals have already conducted extensive research on this topic.

[0003] However, empirical estimation methods, based on engineering experience, generally assume that the residual magnetism of a transformer ranges from 20% to 80% of the saturation flux, resulting in significant errors and an inability to determine the direction of residual magnetism. Residual magnetism calculation methods based on core magnetization models require modeling the core hysteresis loop for different transformers, but modeling different transformers is difficult and prone to significant errors. Residual magnetism measurement methods based on inrush current offer high accuracy but are currently only available in simulation stages, making practical engineering applications difficult and complex. Residual magnetism measurement methods based on transformer leakage flux estimate residual magnetism by establishing the transfer function between transformer leakage flux and core residual magnetism, theoretically offering the highest accuracy. However, the theoretical model for three-phase transformers has not yet been developed, and the method remains in the simulation stage. The voltage integration method, based on the law of electromagnetic induction, only requires the voltage waveform when the transformer is switched off; the magnitude and direction of residual magnetism can be obtained through voltage integration. The voltage integration method is simple in principle and requires few parameters, making it the most widely used residual magnetism estimation method in engineering. However, the error of the voltage integration method is generally 10% to 18% or even greater. Summary of the Invention

[0004] In view of this, the embodiments of this application aim to provide a method, apparatus and electronic device for estimating the residual magnetism of a three-phase transformer, so as to solve the problem that the residual magnetism estimated by the existing voltage integration method has a large error.

[0005] The first aspect of this application provides a method for estimating the residual magnetism of a three-phase transformer. This method includes: for any single-phase transformer in the three-phase transformer, obtaining the voltage amplitude U of that single-phase transformer. m The angular frequency ω of the power supply and the number of turns N1 of the primary coil; based on the voltage amplitude U m The remanent magnetization amplitude Φ is calculated using the angular frequency ω of the power supply and formula (1). m ,

[0006] Φ m =U m / (N1×ω) (1);

[0007] Using the voltage waveform diagram of a single-phase transformer during no-load tripping, the voltage closing angle α and the tripping start time t are obtained. open and the time t of the tripping end open +Δt; based on the residual magnetism amplitude Φ m Voltage closing angle α, opening start time t open and the time t of the tripping end open +Δt, combined with formula (2), the residual magnetism Φ of the single-phase transformer after the circuit breaker is calculated. r ,

[0008]

[0009] In the above scheme, by utilizing the real-time voltage waveform data from the voltage waveform diagram of a single-phase transformer during no-load tripping, parameters such as the voltage closing angle α and the tripping start time t are accurately determined. open and the time t of the tripping end open The residual magnetism of a single-phase transformer after tripping is calculated using key parameters such as +Δt and formula (2) above, thereby replacing the residual magnetism of the transformer containing U. C The complex integral terms are simplified, reducing the computational difficulty and increasing the engineering applicability of the residual magnetism estimation method. Furthermore, for any single-phase transformer in a three-phase transformer, the deviation in the actual opening and closing times of the three-phase circuit breakers is comprehensively considered, thus optimizing the accuracy of the transformer residual magnetism estimation method.

[0010] A second aspect of this application provides an apparatus for estimating the residual magnetism of a three-phase transformer. The apparatus includes an acquisition module and a calculation module. The acquisition module is used to acquire the voltage amplitude U of any single-phase transformer in the three-phase transformer. m The angular frequency ω of the power supply and the number of turns N1 of the primary winding are obtained, and the voltage closing angle α and the opening time t are obtained using the voltage waveform diagram of a single-phase transformer during no-load opening. open and the time t of the tripping end open +Δt. The calculation module is used to calculate based on the voltage amplitude U. m The remanent magnetization amplitude Φ is calculated using the angular frequency ω of the power supply and formula (1). m ,

[0011] Φ m =U m / (N1×ω) (1);

[0012] And based on the residual magnetism amplitude Φ m Voltage closing angle α, opening start time t open and the time t of the tripping end open +Δt, combined with formula (2), the residual magnetism Φ of the single-phase transformer after the circuit breaker is calculated. r ,

[0013]

[0014] A third aspect of this application provides a computer-readable storage medium storing executable instructions for a computer. When executed by a processor, the executable instructions implement the method for estimating the residual magnetism of a three-phase transformer according to the first aspect of this application.

[0015] A fourth aspect of this application provides an electronic device including a processor and a memory. The processor is used to execute the method for estimating the residual magnetism of a three-phase transformer according to the first aspect of this application. The memory is used to store executable instructions of the processor. Attached Figure Description

[0016] Figure 1 The diagram shown is a flowchart illustrating a method for estimating the residual magnetism of a three-phase transformer according to an embodiment of this application.

[0017] Figure 2 The diagram shown is the equivalent circuit diagram of the transformer when it is open under no-load conditions.

[0018] Figure 3 The figure shows the voltage waveform of a single-phase transformer when it is unloaded and tripped.

[0019] Figure 4 The diagram shown is a structural schematic of a device for estimating the residual magnetism of a three-phase transformer according to an embodiment of this application.

[0020] Figure 5 The diagram shown is a structural schematic of an electronic device provided in an embodiment of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Figure 1 The diagram shown is a flowchart illustrating a method for estimating the residual magnetism of a three-phase transformer according to an embodiment of this application. The entity executing this estimation method can be a person, a processor, or a server, etc. Figure 1 As shown, the estimation method includes the following steps.

[0023] S100: For any single-phase transformer in a three-phase transformer, obtain the voltage amplitude U of the single-phase transformer. m The angular frequency ω of the power supply and the number of turns N1 of the primary coil.

[0024] S200: Based on voltage amplitude U mThe remanent magnetization amplitude Φ is calculated using the angular frequency ω of the power supply and formula (1). m .

[0025] Φ m =U m / (N1×ω) (1).

[0026] S300: Using the voltage waveform diagram of a single-phase transformer during no-load tripping, obtain the voltage closing angle α and the tripping start time t. open and the time t of the tripping end open +Δt.

[0027] S400: Based on the residual magnetism amplitude Φ m Voltage closing angle α, opening start time t open and the time t of the tripping end open +Δt, combined with formula (2), the residual magnetism Φ of the single-phase transformer after the circuit breaker is calculated. r .

[0028]

[0029] It should be noted that the voltage closing angle α can also be called the actual three-phase closing angle. The tripping start time t open It can also be referred to as the actual opening time of the circuit breaker.

[0030] According to the technical solution provided in the embodiments of this application, by utilizing the real-time voltage waveform data in the voltage waveform diagram of a single-phase transformer during no-load tripping, parameters such as the voltage closing angle α and the tripping start time t are accurately determined. open and the time t of the tripping end open The residual magnetism of a single-phase transformer after tripping is calculated using key parameters such as +Δt and formula (2) above, thereby replacing the residual magnetism of the transformer containing U. C The complex integral terms are simplified, reducing the computational difficulty and increasing the engineering applicability of the residual magnetism estimation method. Furthermore, for any single-phase transformer in a three-phase transformer, the deviation in the actual opening and closing times of the three-phase circuit breakers is comprehensively considered, thus optimizing the accuracy of the transformer residual magnetism estimation method.

[0031] The following will explain in detail the derivation process of the above formula (2).

[0032] The three-phase transformer is equivalent to a single-phase transformer to facilitate the analysis of the transient process of the transformer closing under no-load conditions. The input voltage U1 on the primary side of the transformer when it is closed under no-load conditions can be expressed as the following formula (3).

[0033] U1=U m sin(ωt+α) (3).

[0034] In equation (3), α is the voltage closing angle, Um ω represents the voltage amplitude, and ω represents the angular frequency of the power supply.

[0035] According to the switching operation procedure of the transformer, the voltage equation when the transformer is closed can be expressed as the following formula (4).

[0036]

[0037] In equation (4), R1 is the equivalent resistance of the primary side and L1 is the equivalent inductance of the primary side. Substituting the inductance L1 = Φ / i1 into equation (4) yields the following equation (5).

[0038]

[0039] Solving the differential equation of formula (5) yields the instantaneous magnetic flux of the transformer, which can be expressed as formula (6) below.

[0040]

[0041] After a period of stable operation, the steady-state instantaneous magnetic flux of the transformer can be expressed as the following formula (7).

[0042] Φ(t)=-Φ m cos(ωt+α) (7).

[0043] Due to the presence of transformer magnetizing inductance, windings, and distributed capacitance of the line, the voltage of the transformer windings does not immediately drop to zero after the circuit breaker has opened. Therefore, the calculation model of the residual magnetism circuit during transformer opening can be equivalent to... Figure 3 , Figure 3 Middle U c This indicates the supporting capacitor.

[0044] Depend on Figure 3 It can be seen that after the circuit breaker CB is disconnected, the primary side of the transformer forms a second-order oscillating circuit. The primary side voltage will undergo a period of attenuation, that is, the core magnetic flux needs a period of attenuation time before it can reach the steady-state residual magnetic flux value.

[0045] Because the capacitor voltage cannot change abruptly at the instant the circuit breaker opens, U... C (t open -)=U C (t open +)=U1(t open -), the magnetic flux equation at the moment the transformer is disconnected can be expressed as the following formula (8).

[0046]

[0047] Therefore, the key to the voltage integration method lies in optimizing the detection accuracy of the measurement system to accurately obtain the upper and lower limits of the integration term.

[0048] According to Kirchhoff's voltage law, we can obtain the following formula (9).

[0049]

[0050] Solving the above differential equation (8) yields the following formula (10).

[0051]

[0052] Analysis of equation (10) shows that the transient voltage exhibits exponential decay, making it difficult to calculate. Considering practical engineering, the voltage of a transformer can be obtained using waveform recording data to capture complete voltage change data, such as... Figure 3 As shown.

[0053] In summary, to simplify the calculation process, t is obtained directly using the waveform recording data. open Key parameters such as α are selected, and the sampling accuracy is chosen as the time scale for discretization integration to ensure the accuracy of the integral calculation. The residual magnetism of the transformer after the circuit breaker is opened can be expressed as the following formula (2).

[0054]

[0055] Considering that the actual opening and closing times of the three-phase circuit breaker are all different, the residual magnetism of the three-phase transformer can be expressed as the following formula (11).

[0056]

[0057] Based on the above analysis, it can be seen that the embodiments of this application, taking into account the actual situation of the transformer and the voltage support effect of the capacitor, established a circuit model for the transformer during tripping, and made full use of the real-time voltage recording data of the transformer, replacing the U-shaped circuit. C The complex integral term was used to derive a formula for calculating the residual magnetism of a transformer (2), thereby reducing the difficulty of calculating the residual magnetism and increasing the engineering applicability of the estimation method. For any single-phase transformer in a three-phase transformer, the voltage waveform diagram corresponding to each single-phase transformer is used to obtain parameters such as the voltage closing angle α and the opening start time t. open and the time t of the tripping end open Key parameters such as +Δt are included to fully account for the deviation in the actual opening and closing time of the three-phase circuit breaker, thereby optimizing the accuracy of the estimation method for transformer residual magnetism.

[0058] Figure 4 The diagram shown is a structural schematic of a device for estimating the residual magnetism of a three-phase transformer according to an embodiment of this application. Figure 4As shown, the estimation device 100 includes an acquisition module 110 and a calculation module 120. The acquisition module 110 is used to acquire the voltage amplitude U of any single-phase transformer in a three-phase transformer. m The angular frequency ω of the power supply and the number of turns N1 of the primary winding are obtained, and the voltage closing angle α and the opening time t are obtained using the voltage waveform diagram of a single-phase transformer during no-load opening. open and the time t of the tripping end open +Δt. Calculation module 120 is used to calculate based on voltage amplitude U m The remanent magnetization amplitude Φ is calculated using the angular frequency ω of the power supply and formula (1). m ,

[0059] Φ m =U m / (N1×ω) (1);

[0060] And based on the residual magnetism amplitude Φ m Voltage closing angle α, opening start time t open and the time t of the tripping end open +Δt, combined with formula (2), the residual magnetism Φ of the single-phase transformer after the circuit breaker is calculated. r ,

[0061]

[0062] It should be noted that the estimation device 100 is the device corresponding to the estimation method for the residual magnetism of a three-phase transformer provided in the above-described embodiments of this application. Therefore, each module in the estimation device can implement the corresponding evaluation method, and the estimation device can at least achieve the above-described corresponding technical effects, which will not be elaborated here.

[0063] Figure 5 The diagram shown is a block diagram of an electronic device provided in one embodiment of this application.

[0064] Reference Figure 5 The electronic device 10 includes a processor 11 and a memory 12. The memory 12 stores instructions executable by the processor 11, such as application programs. There can be one or more processors 11. The application programs stored in the memory 12 can include one or more modules, each corresponding to a set of instructions. Furthermore, the processor 11 is configured to execute instructions to perform the aforementioned method for estimating the residual magnetism of a three-phase transformer.

[0065] Electronic device 10 may also include a power supply component configured for power management, a wired or wireless network interface configured to connect electronic device 10 to a network, and an input / output (I / O) interface. Electronic device 10 can operate on an operating system, such as Windows Server, stored in memory 12.TM Mac OSX TM Unix TM Linux TM FreeBSD TM Or similar.

[0066] A non-transitory computer-readable storage medium, when the instructions in the storage medium are executed by the processor of the aforementioned electronic device 10, enables the electronic device 10 to execute a method for estimating the residual magnetism of a three-phase transformer. The estimation method is executed by an agent program and includes: for any single-phase transformer in the three-phase transformer, obtaining the voltage amplitude U of the single-phase transformer. m The angular frequency ω of the power supply and the number of turns N1 of the primary coil; based on the voltage amplitude U m The remanent magnetization amplitude Φ is calculated using the angular frequency ω of the power supply and formula (1). m ,

[0067] Φ m =U m / (N1×ω) (1);

[0068] Using the voltage waveform diagram of a single-phase transformer during no-load tripping, the voltage closing angle α and the tripping start time t are obtained. open and the time t of the tripping end open +Δt; based on the residual magnetism amplitude Φ m Voltage closing angle α, opening start time t open and the time t of the tripping end open +Δt, combined with formula (2), the residual magnetism Φ of the single-phase transformer after the circuit breaker is calculated. r .

[0069]

[0070] Those skilled in the art will recognize that the algorithmic steps of the various examples described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0071] In the several embodiments provided in this application, it should be understood that the disclosed estimation methods and devices can be implemented in other ways. For example, the estimation device embodiments described above are merely illustrative. For instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules may be combined or integrated into another system, or some features may be ignored or not executed.

[0072] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program verification codes, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0073] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the estimation device and electronic device described above can be referred to the corresponding process in the foregoing estimation method embodiments, and will not be repeated here.

[0074] It should be noted that the combination of the technical features in the embodiments of this application is not limited to the combination methods described in the embodiments of this application or the combination methods described in specific embodiments. All technical features described in this application can be freely combined or combined in any way, unless they contradict each other.

[0075] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for estimating the residual magnetism of a three-phase transformer, characterized in that, include: For any single-phase transformer in a three-phase transformer, obtain the voltage amplitude U of the single-phase transformer. m The angular frequency ω of the power supply and the number of turns N1 of the primary coil; According to the voltage amplitude U m The residual magnetism amplitude Φ is calculated using the angular frequency ω of the power supply and formula (1). m , Φ m =U m / (N1×ω) (1); Using the voltage waveform diagram of the single-phase transformer during no-load opening, the voltage closing angle can be obtained. α , circuit breaker start time t open and the time t of the tripping end open + t; According to the remanence amplitude Φ m The voltage closing angle α、 The tripping start time t open and the tripping end time t open + t, combined with formula (2), the residual magnetism Φ of the single-phase transformer after the circuit breaker is calculated. r , （2）； The derivation process of formula (2) is as follows: The three-phase transformer is equivalent to a single-phase transformer to facilitate the analysis of the transient process of the transformer being closed under no-load conditions. The input voltage U1 of the primary side of the transformer when it is closed under no-load conditions is expressed as the following formula (3). （3）， In formula (3), α It is the voltage closing angle. U m Voltage amplitude, ω The angular frequency of the power supply. According to the switching operation procedure of the transformer, the voltage equation when the transformer is closed is expressed as the following formula (4). （4）， In formula (4), R 1 represents the equivalent resistance of the primary side. L 1 represents the primary-side equivalent inductance, and the inductance... L 1= Φ / i Substituting 1 into formula (4) yields the following formula (5). （5）， Solving the differential equation of formula (5) yields the instantaneous magnetic flux of the transformer, which is expressed as formula (6) below. （6）， After a period of stable operation, the steady-state instantaneous magnetic flux of the transformer is expressed by the following formula (7). （7）， Because the capacitor voltage cannot change abruptly at the instant the circuit breaker opens. U C ( t open -)= U C ( t open +)= U 1( t open -), the magnetic flux equation at the moment the transformer is disconnected is expressed as the following formula (8). （8）， According to Kirchhoff's voltage law, we have the following formula (9). （9）， Solving formula (8) yields the following formula (10). （10）， According to formula (10), the voltage of the transformer is obtained by using waveform recording data to obtain complete voltage change data. Key parameters are directly obtained using waveform recording data. Sampling accuracy is selected as the time scale for discretization integration. The residual magnetism of the transformer after switching off is expressed as formula (2). Key parameters include... t open , α .

2. A device for estimating the residual magnetism of a three-phase transformer, characterized in that, include: The acquisition module is used to acquire the voltage amplitude U of any single-phase transformer in a three-phase transformer. m The angular frequency ω of the power supply and the number of turns N1 of the primary winding are determined, and the voltage closing angle is obtained using the voltage waveform diagram of the single-phase transformer during no-load opening. α , circuit breaker start time t open and the time t of the tripping end open + t; The calculation module is used to calculate the voltage amplitude U. m The residual magnetism amplitude Φ is calculated using the angular frequency ω of the power supply and formula (1). m , Φ m =U m / (N1×ω) (1); And based on the remanent magnetization amplitude Φ m Voltage closing angle α、 Tripping start time t open and the time t of the tripping end open + t, combined with formula (2), the residual magnetism Φ of the single-phase transformer after the circuit breaker is calculated. r , （2）， The derivation process of formula (2) is as follows: The three-phase transformer is equivalent to a single-phase transformer to facilitate the analysis of the transient process of the transformer being closed under no-load conditions. The input voltage U1 of the primary side of the transformer when it is closed under no-load conditions is expressed as the following formula (3). （3）， In formula (3), α It is the voltage closing angle. U m Voltage amplitude, ω The angular frequency of the power supply. According to the switching operation procedure of the transformer, the voltage equation when the transformer is closed is expressed as the following formula (4). （4）， In formula (4), R 1 represents the equivalent resistance of the primary side. L 1 represents the primary-side equivalent inductance, and the inductance... L 1= Φ / i Substituting 1 into formula (4) yields the following formula (5). （5）， Solving the differential equation of formula (5) yields the instantaneous magnetic flux of the transformer, which is expressed as formula (6) below. （6）， After a period of stable operation, the steady-state instantaneous magnetic flux of the transformer is expressed by the following formula (7). （7）， Because the capacitor voltage cannot change abruptly at the instant the circuit breaker opens. U C ( t open -)= U C ( t open +)= U 1( t open -), the magnetic flux equation at the moment the transformer is disconnected is expressed as the following formula (8). （8）， According to Kirchhoff's voltage law, we have the following formula (9). （9）， Solving formula (8) yields the following formula (10). （10）， According to formula (10), the voltage of the transformer is obtained by using waveform recording data to obtain complete voltage change data. Key parameters are obtained directly using waveform recording data. The sampling accuracy is selected as the time scale for discretization integration. The residual magnetism of the transformer after the circuit breaker is opened is expressed as formula (2).

3. A computer-readable storage medium having executable instructions stored thereon, characterized in that, When the executable instructions are executed by the processor, they implement the method for estimating the residual magnetism of a three-phase transformer as described in claim 1.

4. An electronic device, characterized in that, include: A processor for executing the method for estimating the residual magnetism of a three-phase transformer as described in claim 1; as well as Memory for storing the executable instructions of the processor.

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