Online PT turn-to-turn short circuit detection method and system based on Lissajous figure

Abstract

The invention discloses a PT turn-to-turn short circuit online detection method and system based on a Lissajous figure, and the method comprises the following steps: S1, collecting PT primary side voltage # imgabs0 # and PT secondary side voltage # imgabs1 # and PT secondary side current signals # imgabs2 #; S2, calculating the characteristic parameters of the Lissajous figure according to the collected PT primary side voltage, PT secondary side voltage and PT secondary side current signals; the characteristic parameters comprise a long axis a, a short axis b and an inclination angle beta; s3, judging whether a set turn-to-turn short circuit rule is met or not according to the calculated characteristic parameters of the Lissajous figure; s4, if the set turn-to-turn short circuit rule is met, a PT primary side switch is switched off, and a PT turn-to-turn short circuit alarm signal is sent out; otherwise, turning to the step S1. According to the invention, the problem that the traditional detection method cannot accurately monitor the PT turn-to-turn short circuit fault in real time is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of PT online detection, and in particular relates to a PT turn-to-turn short circuit online detection method and system based on Lissajous figures. Background Art

[0002] The generator PT plays a role in metering, excitation and protection of the generator output voltage. However, due to factors such as the operating environment and manufacturing process, the generator PT turn-to-turn short circuit has caused unplanned shutdown of the unit. Therefore, the study of the online detection device and method for the generator PT turn-to-turn short circuit has improved the detection efficiency of the generator PT insulation fault and greatly reduced the risk of abnormal shutdown of the generator, which is of great significance to ensuring the safe production of electricity and the economic benefits of power generation enterprises.

[0003] The existing methods for detecting generator PT inter-turn short-circuit faults mainly include DC resistance measurement, no-load current measurement and inductive withstand voltage. The above traditional detection methods are capable of inspecting PT main insulation defects, but have disadvantages such as poor sensitivity in detecting inter-turn short-circuit faults. In addition, the detection of PT inter-turn insulation status must be carried out after the generator is shut down, which is not conducive to the timely and effective detection of insulation defects, and has low efficiency and poor accuracy. Therefore, it is urgent to design a PT inter-turn short-circuit online detection method and system based on Lissajous figures to help power plant operation and maintenance personnel detect faults in time and reduce the risk of unplanned shutdowns.

[0004] The Chinese patent with the publication number CN118641820A discloses a primary small current phasor measurement method suitable for PT turn-to-turn short circuit detection, which uses a through-core CT with source conversion function to collect three-phase PT-to-ground current, and the through-core CT converts the current small signal into a voltage signal, and uses a shielded grounding cable to send the signal to the protection device; the protection device uses a PT that matches the through-core CT secondary to collect the voltage signal, and obtains the secondary sampling instantaneous value of the three-phase PT-to-ground current of the protection device; the software of the protection device stores the original sampling instantaneous value to obtain a three-phase PT-to-ground current sampling sequence, and the protection program uses an anti-bad point processing algorithm to process the sampling points, and then uses a bandpass filter to filter out interference signals to obtain a new sampling value sequence; Based on the new sampling value sequence, Fourier calculation is used to obtain the phasor of the three-phase PT-to-ground current that can be directly used for PT turn-to-turn short circuit discrimination. Although the method described in the invention calculates the phasor through fast sampling and Fourier transform, the overall calculation process may cause delays, especially in the anti-bad point processing and filtering links. This delay may affect real-time performance; at the same time, although this method improves signal quality through bandpass filtering and anti-bad pixel processing, under conditions of strong electromagnetic interference or transient interference, the filtering effect may not be ideal, resulting in signal distortion. Summary of the invention

[0005] The present invention provides a PT turn-to-turn short circuit online detection method and system based on Lissajous figures, aiming to solve the problem that traditional detection methods cannot monitor PT turn-to-turn short circuit faults in real time and accurately.

[0006] In order to solve the above technical problems, the present invention provides a PT turn-to-turn short circuit online detection method based on Lissajous figures, comprising the following steps:

[0007] S1: Collect PT primary voltage and PT secondary voltage PT secondary current signal

[0008] S2: Calculate characteristic parameters of the Lissajous figure according to the collected PT primary voltage, PT secondary voltage and PT secondary current signals, wherein the characteristic parameters include a major axis a, a minor axis b and an inclination angle β.

[0009] S3: judging whether the set turn-to-turn short-circuit rule is satisfied according to the calculated characteristic parameters of the Lissajous figure.

[0010] S4: If the set turn-to-turn short-circuit rule is met, the PT primary side switch is disconnected and a PT turn-to-turn short-circuit alarm signal is issued; otherwise, go to step S1.

[0011] Preferably, in step S1, the PT primary voltage needs to be collected at all times. and PT secondary voltage PT secondary current signal In addition, signal acquisition must meet clock synchronization requirements and ensure that the phase difference between each signal after acquisition deviates from the actual value by less than ±5°.

[0012] Preferably, before calculating the characteristic parameters of the Lissajous figure in step S2, the PT primary side voltage and PT secondary voltage PT secondary current signal They are respectively converted into the corresponding primary side voltage per unit value U1, secondary side voltage per unit value U2, and secondary side current per unit value I2.

[0013] Preferably, when calculating the characteristic parameters of the Lissajous figure in step S2, the secondary side current per unit value I2 is used as the horizontal axis, and the difference ΔU=U1-U2 between the primary side voltage per unit value U1 and the secondary side voltage per unit value U2 is used as the vertical axis.

[0014] Preferably, the Lissajous figure is an ellipse, and when calculating the tilt angle β, the positive direction is the horizontal right horizontal axis direction and the counterclockwise rotation is taken as the positive direction.

[0015] Preferably, the turn-to-turn short-circuit rule in step S3 is specifically:

[0016] When the feature value f1 is greater than the set threshold f 1set And the feature value f2 is less than the set threshold f 2set When , it is determined that a turn-to-turn short circuit fault occurs in the PT.

[0017] The calculation formulas of the characteristic quantities f1 and f2 are:

[0018] f1=a / b

[0019] f2=cosβ

[0020] Where a, b, and β are the characteristic parameters of the Lissajous figure.

[0021] On the other hand, the present invention provides a PT turn-to-turn short circuit online detection system based on Lissajous figures, comprising a switch, a voltage divider, a voltage measurement unit, a current measurement unit and a microcomputer system.

[0022] The generator and the PT are connected through a switch, the primary side of the PT is connected to the input end of the voltage divider, the secondary side of the PT is connected to the input end of the voltage measuring unit and the input end of the current measuring unit respectively, and the microcomputer system is connected to the output end of the voltage divider, the output end of the voltage measuring unit, and the output end of the current measuring unit respectively.

[0023] The voltage divider is used to convert the PT primary side voltage into a weak current signal for easy collection and analysis; the voltage measurement unit and the current measurement unit are used to measure the voltage signal and the current signal of the PT secondary side respectively; the microcomputer system analyzes whether there is a turn-to-turn short circuit fault in the PT based on the collected PT primary side voltage signal, PT secondary side voltage signal and PT secondary side current signal through signal processing.

[0024] On the other hand, the present invention also provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the online detection method for PT turn-to-turn short circuit based on Lissajous figures as described in any embodiment of the present invention when executing the computer program.

[0025] On the other hand, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the method for online detection of PT turn-to-turn short circuit based on Lissajous figures as described in any embodiment of the present invention is implemented.

[0026] Compared with the prior art, the present invention has the following technical effects:

[0027] The PT turn-to-turn short-circuit online detection method based on Lissajous figures proposed in the present invention can realize real-time monitoring of the PT operating status by continuously collecting the PT primary voltage, secondary voltage and secondary current signals. This real-time performance enables the system to respond quickly to potential turn-to-turn short-circuit faults, ensuring that timely measures are taken when faults occur to reduce the risk of equipment damage; by constructing Lissajous figures based on the per-unit current and voltage difference, the relationship between current and voltage is reflected, which helps to more accurately determine whether a turn-to-turn short-circuit occurs. The method described in the present invention significantly improves the fault detection capability of the PT through real-time monitoring, precise calculation, effective fault discrimination mechanism and automated response. This method not only enhances the safety and stability of the power system, but also reduces the operation and maintenance costs, providing a strong guarantee for the reliable operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is an overall flow chart of the online detection method for PT turn-to-turn short circuit based on Lissajous figures of the present invention;

[0029] Figure 2 is a schematic diagram of defining characteristic parameters of the Lissajous figure of the present invention;

[0030] Figure 3 It is a simulation result diagram of the Lissajous figure when the PT turns are short-circuited according to the present invention;

[0031] Figure 4 It is an overall structural diagram of the PT turn-to-turn short circuit online detection system based on Lissajous figures described in the present invention.

[0032] In the figure: 1. switch; 2. voltage divider; 3. voltage measuring unit; 4. current measuring unit; 5. microcomputer system. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in combination with specific embodiments of the present application and with reference to the accompanying drawings.

[0034] Embodiment 1

[0035] This embodiment provides a PT turn-to-turn short circuit online detection method based on Lissajous figures, see Figure 1 As shown, the following steps are included:

[0036] S1: Collect PT primary voltage and PT secondary voltage PT secondary current signal

[0037] S2: Calculate characteristic parameters of the Lissajous figure according to the collected PT primary voltage, PT secondary voltage and PT secondary current signals, wherein the characteristic parameters include a major axis a, a minor axis b and an inclination angle β.

[0038] S3: judging whether the set turn-to-turn short-circuit rule is satisfied according to the calculated characteristic parameters of the Lissajous figure.

[0039] S4: If the set turn-to-turn short-circuit rule is met, the PT primary side switch is disconnected and a PT turn-to-turn short-circuit alarm signal is issued; otherwise, go to step S1.

[0040] As a preferred implementation of this embodiment, the step S1 needs to collect the PT primary side voltage at all times. and PT secondary voltage PT secondary current signal In addition, signal acquisition must meet clock synchronization requirements and ensure that the phase difference between each signal after acquisition deviates from the actual value by less than ±5°.

[0041] As a preferred implementation of this embodiment, before calculating the characteristic parameters of the Lissajous figure in step S2, the PT primary side voltage and PT secondary voltage PT secondary current signal They are respectively converted into the corresponding primary side voltage per unit value U1, secondary side voltage per unit value U2, and secondary side current per unit value I2.

[0042] As a preferred implementation of this embodiment, when calculating the characteristic parameters of the Lissajous figure in step S2, the secondary side current per unit value I2 is used as the horizontal axis, and the difference ΔU=U1-U2 between the primary side voltage per unit value U1 and the secondary side voltage per unit value U2 is used as the vertical axis.

[0043] I2 and ΔU are both sinusoidal signals, and their mathematical expressions can be expressed as the following formula:

[0044]

[0045] Where A1 and A2 are the signal amplitudes of I2 and ΔU respectively; ω1 and ω2 are the angular frequencies of I2 and ΔU respectively; t is the time, usually in milliseconds; They are the initial phases of I2 and ΔU respectively.

[0046] make:

[0047]

[0048] The mathematical expression of the Lissajous figure is:

[0049]

[0050] In the formula, is the phase difference.

[0051] As a preferred implementation of this embodiment, refer to Figure 2 As shown, the Lissajous figure is an ellipse, and the major axis a, minor axis b and tilt angle β of the ellipse are used as characteristic parameters. When calculating the tilt angle β, the horizontal right horizontal axis direction and counterclockwise rotation are regarded as the positive direction. Specifically, the calculation formula of the characteristic parameters is:

[0052] a=2A1

[0053] b=2A2

[0054]

[0055] As a preferred implementation of this embodiment, the turn-to-turn short-circuit rule in step S3 is specifically:

[0056] When the feature value f1 is greater than the set threshold f 1set And the feature value f2 is less than the set threshold f 2set When the PT is judged to have a turn-to-turn short circuit fault, it should be noted that the f 1set and f 2set It is a constant calculated based on the factory parameters of the PT, such as the rated voltage, short-circuit impedance, no-load excitation current, etc. It can be modified according to the specific equipment conditions. 1set The value range of f is generally 2 to 3. 2set The value range is generally 0.8 to 0.9.

[0057] The calculation formulas of the characteristic quantities f1 and f2 are:

[0058] f1=a / b

[0059] f2=cosβ

[0060] Where a, b, and β are the characteristic parameters of the Lissajous figure.

[0061] See also Figure 3 As shown in the figure, when a turn-to-turn short circuit occurs in the PT, the characteristic parameters of the Lissajous figure, the major axis a, the minor axis b and the inclination angle β, are significantly different from those of the normal winding, and the characteristic quantities f1 and f2 change significantly, which can be used as a criterion for detecting PT turn-to-turn short circuits.

[0062] Embodiment 2

[0063] Accordingly, see Figure 4As shown, this embodiment provides a PT turn-to-turn short-circuit online detection system based on Lissajous figures, and the system implements the PT turn-to-turn short-circuit online detection method based on Lissajous figures as described in any embodiment of the present invention, including a switch 1, a voltage divider 2, a voltage measurement unit 3, a current measurement unit 4 and a microcomputer system 5.

[0064] The generator and the PT are connected via a switch 1, the primary side of the PT is connected to the input end of the voltage divider 2, the secondary side of the PT is connected to the input end of the voltage measuring unit 3 and the input end of the current measuring unit 4 respectively, and the microcomputer system 5 is connected to the output end of the voltage divider 2, the output end of the voltage measuring unit 3, and the output end of the current measuring unit 4 respectively.

[0065] The voltage divider 2 is used to convert the PT primary side voltage into a weak current signal for easy collection and analysis; the voltage measurement unit 3 and the current measurement unit 4 are used to measure the voltage signal and current signal of the PT secondary side respectively; the microcomputer system 5 analyzes whether there is a turn-to-turn short circuit fault in the PT based on the collected PT primary side voltage signal, PT secondary side voltage signal and PT secondary side current signal through signal processing. The switch 1 is opened and closed under the control of the microcomputer system 5. When a turn-to-turn short circuit fault occurs in the PT, the microcomputer system 5 sends a PT turn-to-turn short circuit alarm signal and controls the switch 1 to be disconnected.

[0066] As a preferred implementation of this embodiment, the maximum offset of the phase-frequency characteristic of the voltage divider 2, voltage measuring unit 3 and current measuring unit 4 in the frequency range of 20Hz to 1000Hz is less than ±3°. The current measuring unit 4 is a high-precision current measuring unit with a resolution of not less than 1mA.

[0067] Embodiment 3

[0068] This embodiment provides an electronic device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the online detection method for PT turn-to-turn short circuit based on Lissajous figures as described in any embodiment of the present invention is implemented.

[0069] Embodiment 4

[0070] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for online detection of PT turn-to-turn short circuit based on Lissajous figures as described in any embodiment of the present invention is implemented.

[0071] In the embodiments of the present application, "at least one" refers to one or more, and "more than one" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can be represented by: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, c can be single or multiple.

[0072] Those of ordinary skill in the art will appreciate that the various units and algorithm steps described in the embodiments disclosed herein can be implemented in a combination of electronic hardware, computer software, and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0073] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0074] In several embodiments provided in the present application, if any 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 application, 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, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory; hereinafter referred to as: ROM), random access memory (Random Access Memory; hereinafter referred to as: RAM), disk or optical disk, and other media that can store program codes.

[0075] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A PT turn-to-turn short circuit online detection method based on Lissajous figures, characterized in that: The following steps are involved: S1: Collect PT primary voltage and PT secondary voltage PT secondary current signal S2: Calculate characteristic parameters of the Lissajous figure according to the collected PT primary side voltage, PT secondary side voltage and PT secondary side current signals, wherein the characteristic parameters include a major axis a, a minor axis b and an inclination angle β; S3: judging whether the set turn-to-turn short-circuit rule is satisfied according to the characteristic parameters of the calculated Lissajous figure; S4: If the set turn-to-turn short-circuit rule is met, the PT primary side switch is disconnected and a PT turn-to-turn short-circuit alarm signal is issued; otherwise, go to step S1.

2. The PT turn-to-turn short circuit online detection method based on Lissajous figures according to claim 1 is characterized in that: In step S1, the PT primary voltage needs to be collected at all times. and PT secondary voltage PT secondary current signal In addition, signal acquisition must meet clock synchronization requirements and ensure that the phase difference between each signal after acquisition deviates from the actual value by less than ±5°.

3. The PT turn-to-turn short circuit online detection method based on Lissajous figures according to claim 1 is characterized in that: Before calculating the characteristic parameters of the Lissajous figure in step S2, the PT primary side voltage and PT secondary voltage PT secondary current signal They are respectively converted into the corresponding primary side voltage per unit value U1, secondary side voltage per unit value U2, and secondary side current per unit value I2.

4. The method for online detection of PT turn-to-turn short circuit based on Lissajous figures according to claim 1 is characterized in that: When calculating the characteristic parameters of the Lissajous figure in step S2, the secondary current per unit value I2 is used as the horizontal axis, and the difference ΔU=U1-U2 between the primary voltage per unit value U1 and the secondary voltage per unit value U2 is used as the vertical axis.

5. The PT turn-to-turn short circuit online detection method based on Lissajous figures according to any one of claims 1 to 4, characterized in that: The Lissajous figure is an ellipse, and when calculating the tilt angle β, the positive direction is the horizontal right horizontal axis direction and the counterclockwise rotation direction.

6. The method for online detection of PT turn-to-turn short circuit based on Lissajous figures according to claim 1, characterized in that: The turn-to-turn short-circuit rule in step S3 is specifically: When the feature value f1 is greater than the set threshold f 1set And the feature value f2 is less than the set threshold f 2set When , it is determined that the PT has a turn-to-turn short circuit fault; The calculation formulas of the characteristic quantities f1 and f2 are: f1=a / b f2=cosβ Where a, b, and β are the characteristic parameters of the Lissajous figure.

7. A PT turn-to-turn short circuit online detection system based on Lissajous figures, characterized in that: The system is implemented based on the PT turn-to-turn short circuit online detection method based on Lissajous figures according to any one of claims 1 to 6, and comprises a switch (1), a voltage divider (2), a voltage measurement unit (3), a current measurement unit (4) and a microcomputer system (5); The generator and the PT are connected via a switch (1); the primary side of the PT is connected to the input end of a voltage divider (2); the secondary side of the PT is respectively connected to the input end of a voltage measuring unit (3) and the input end of a current measuring unit (4); and the microcomputer system (5) is respectively connected to the output end of the voltage divider (2), the output end of the voltage measuring unit (3), and the output end of the current measuring unit (4); The voltage divider (2) is used to convert the PT primary side voltage into a weak current signal for easy collection and analysis; the voltage measurement unit (3) and the current measurement unit (4) are used to measure the voltage signal and the current signal of the PT secondary side respectively; the microcomputer system (5) analyzes whether the PT has an inter-turn short circuit fault through signal processing based on the collected PT primary side voltage signal, PT secondary side voltage signal and PT secondary side current signal.

8. An electronic device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the PT turn-to-turn short circuit online detection method based on Lissajous figures as described in any one of claims 1 to 6 when executing the computer program.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the online detection method for PT turn-to-turn short circuit based on Lissajous figures according to any one of claims 1 to 6 is implemented.

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