A method for judging excitation system rectifier bridge trigger pulse loss fault

Abstract

The application discloses a method for judging excitation system rectifier bridge trigger pulse loss fault, and a protection device measures three-phase current on a high-voltage side of an excitation transformer, three-phase current on a low-voltage side of the excitation transformer and a generator rotor voltage; calculates a fundamental wave effective value and a second harmonic effective value of three-phase differential current of the excitation transformer, a root mean square effective value and a fundamental wave effective value of the generator rotor voltage; in response to the fundamental wave effective value of the three-phase differential current of the excitation transformer being greater than a first fixed value threshold, the ratio of the maximum value of the second harmonic effective value of the three-phase differential current of the excitation transformer to the maximum value of the fundamental wave effective value being greater than a second fixed value threshold, and the ratio of the fundamental wave effective value of the generator rotor voltage to the root mean square effective value being greater than a third fixed value threshold, the excitation system rectifier bridge trigger pulse loss fault is judged, and the protection device is delayed for a time t and then acts to alarm. The method uses the electrical quantities collected by the generator protection device to judge, and can significantly improve the troubleshooting efficiency when the generator excitation system fails.

Description

Technical Field

[0001] This invention belongs to the field of power system relay protection and relates to a method for identifying faults caused by the loss of trigger pulses in the rectifier bridge of an excitation system. Background Technology

[0002] When the trigger pulse of the excitation system rectifier bridge is lost, it may cause the generator loss-of-excitation protection or the excitation transformer differential protection to trip. For example, the loss of the excitation rectifier bridge trigger pulse in a 700MW hydropower unit led to the tripping of the generator loss-of-excitation protection. A pumped-storage unit experienced a fault in the excitation rectifier bridge trigger pulse loss, causing the excitation transformer differential protection to trip. Because the protection action elements in these situations do not directly correspond to the actual fault type, it greatly confuses the fault diagnosis process, potentially misleading the direction of troubleshooting and delaying fault repair.

[0003] Therefore, there is an urgent need to study a rapid diagnostic method for the fault of lost trigger pulse in the rectifier bridge of the excitation system, which can greatly shorten the time for fault diagnosis and repair. Summary of the Invention

[0004] The main objective of this invention is to provide a method for identifying faults caused by the loss of trigger pulses in the rectifier bridge of an excitation system, thereby improving the efficiency of fault diagnosis in the excitation system.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] In a first aspect, the present invention provides a method for determining the fault of lost trigger pulse in a rectifier bridge of an excitation system, comprising:

[0007] Step (1): Obtain the three-phase current on the high-voltage side of the excitation transformer, the three-phase current on the low-voltage side of the excitation transformer, and the generator rotor voltage as measured by the protection device;

[0008] Step (2): Based on the three-phase current on the high-voltage side of the excitation transformer, the three-phase current on the low-voltage side of the excitation transformer, and the generator rotor voltage, calculate the fundamental effective value and the second harmonic effective value of the three-phase differential current of the excitation transformer, and the root mean square effective value and the fundamental effective value of the generator rotor voltage.

[0009] Step (3): In response to the fact that the fundamental effective value of the three-phase differential current of the excitation transformer is greater than the first set threshold and the ratio of the maximum value of the second harmonic effective value of the three-phase differential current of the excitation transformer to the maximum value of the fundamental effective value is greater than the second set threshold, and the ratio of the fundamental effective value to the root mean square effective value of the generator rotor voltage is greater than the third set threshold, it is determined that the excitation system rectifier bridge trigger pulse loss fault is present.

[0010] Step (4): In response to the judgment that the excitation system rectifier bridge trigger pulse is lost, after a delay t, the protection device will activate the alarm.

[0011] In step (1), the three-phase current on the high-voltage side of the excitation transformer, the three-phase current on the low-voltage side of the excitation transformer, and the generator rotor voltage measured by the protection device are respectively from the current transformer on the high-voltage side of the excitation transformer, the current transformer on the low-voltage side of the excitation transformer, and the positive and negative terminals of the rotor winding.

[0012] In some embodiments, the calculation method for the fundamental effective value and the second harmonic effective value of the three-phase differential current of the excitation transformer in step (2) includes: obtaining the three-phase differential current of the excitation transformer based on the three-phase current on the high-voltage side and the three-phase current on the low-voltage side of the excitation transformer, and calculating the fundamental effective value and the second harmonic effective value of the three-phase differential current of the excitation transformer using the Fourier algorithm based on the three-phase differential current of the excitation transformer;

[0013] In step (2), the fundamental effective value of the generator rotor voltage is calculated using the Fourier algorithm based on the generator rotor voltage;

[0014] In step (2), the method for calculating the root mean square effective value of the generator rotor voltage includes:

[0015]

[0016] Among them, U r.M (i) is the current root mean square effective value of the generator rotor voltage; U r (ij) represents the rotor voltage at the previous j points, and N represents the number of sampling points in one power frequency cycle.

[0017] In some embodiments, the method for calculating the ratio of the maximum effective value of the second harmonic to the maximum effective value of the fundamental wave in step (3) of the excitation transformer includes:

[0018]

[0019] Where K1 is the ratio of the maximum effective value of the second harmonic to the maximum effective value of the fundamental harmonic of the three-phase differential current of the excitation transformer; I dA.2ω I dB.2ω I dC.2ω I represents the effective value of the second harmonic of the three-phase differential current of the excitation transformer. dA.1ω I dB.1ω I dC.1ω This represents the fundamental effective value of the three-phase differential current of the excitation transformer.

[0020] In some embodiments, the method for calculating the ratio of the fundamental effective value to the root mean square effective value of the generator rotor voltage in step (3) includes:

[0021]

[0022] Among them, K r U is the ratio of the fundamental RMS value to the root mean square RMS value of the rotor voltage. r.1ω U is the fundamental effective value of the rotor voltage; r.M This is the root mean square effective value of the rotor voltage.

[0023] In some embodiments, in step (3), the first fixed threshold I d.set The setting is based on 20%-30% of the rated current on the reference side of the excitation transformer, with the second setting threshold K. 1.set The value ranges from 0.1 to 0.15, with the third fixed threshold K. 2.set The value ranges from 0.5 to 0.7.

[0024] In some embodiments, in step (4), the delay t is 0.1s-5s.

[0025] In a second aspect, the present invention provides a fault detection device for the loss of trigger pulse of rectifier bridge in an excitation system, including a processor and a storage medium;

[0026] The storage medium is used to store instructions;

[0027] The processor is configured to operate according to the instructions to perform the steps of the method according to the first aspect.

[0028] Thirdly, the present invention provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0029] Fourthly, the present invention provides a computing device, comprising:

[0030] One or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing any of the methods described in the first aspect.

[0031] The beneficial effects of this invention are: by using the electrical quantities collected by the generator protection for discrimination, no additional sensors are needed, and the fault of lost trigger pulse of rectifier bridge in excitation system can be quickly identified, which greatly improves the efficiency of fault diagnosis in excitation system. Attached Figure Description

[0032] Figure 1 This invention provides a method for identifying faults caused by the loss of trigger pulses in the rectifier bridge of an excitation system. In the figure, K1 is the ratio of the maximum effective value of the second harmonic to the maximum effective value of the fundamental wave in the three-phase differential current of the excitation transformer; I dA.2ω I dB.2ω I dC.2ωI represents the effective value of the second harmonic of the three-phase differential current of the excitation transformer. dA.1ω I dB.1ω I dC.1ω K represents the fundamental effective value of the three-phase differential current of the excitation transformer. 1.set This is a set threshold for the ratio of the maximum effective value of the second harmonic to the maximum effective value of the fundamental harmonic of the three-phase differential current of the excitation transformer; I d.set K1 is the current-carrying setpoint threshold for the differential current of the excitation transformer; K2 is the ratio of the fundamental RMS value to the root mean square RMS value of the rotor voltage; U r.1ω U is the fundamental effective value of the rotor voltage; r.M K represents the root mean square effective value of the rotor voltage. 2.set t is the threshold value for the ratio of the fundamental effective value to the root mean square effective value of the rotor voltage; t is the protection action delay. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be used to limit the scope of protection of the present invention.

[0034] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0035] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0036] Example 1

[0037] A method for detecting faults in the rectifier bridge of an excitation system due to lost trigger pulses includes:

[0038] Step (1): Obtain the three-phase current on the high-voltage side of the excitation transformer, the three-phase current on the low-voltage side of the excitation transformer, and the generator rotor voltage as measured by the protection device;

[0039] Step (2): Based on the three-phase current on the high-voltage side of the excitation transformer, the three-phase current on the low-voltage side of the excitation transformer, and the generator rotor voltage, calculate the fundamental effective value and the second harmonic effective value of the three-phase differential current of the excitation transformer, and the root mean square effective value and the fundamental effective value of the generator rotor voltage.

[0040] Step (3): In response to the fact that the fundamental effective value of the three-phase differential current of the excitation transformer is greater than the first set threshold and the ratio of the maximum value of the second harmonic effective value of the three-phase differential current of the excitation transformer to the maximum value of the fundamental effective value is greater than the second set threshold, and the ratio of the fundamental effective value to the root mean square effective value of the generator rotor voltage is greater than the third set threshold, it is determined that the excitation system rectifier bridge trigger pulse loss fault is present.

[0041] Step (4): In response to the judgment that the excitation system rectifier bridge trigger pulse is lost, after a delay t, the protection device will activate the alarm.

[0042] In step (1), the three-phase current on the high-voltage side of the excitation transformer, the three-phase current on the low-voltage side of the excitation transformer, and the generator rotor voltage measured by the protection device are respectively from the current transformer on the high-voltage side of the excitation transformer, the current transformer on the low-voltage side of the excitation transformer, and the positive and negative terminals of the rotor winding.

[0043] In some embodiments, the calculation method for the fundamental effective value and the second harmonic effective value of the three-phase differential current of the excitation transformer in step (2) includes: obtaining the three-phase differential current of the excitation transformer based on the three-phase current on the high-voltage side and the three-phase current on the low-voltage side of the excitation transformer, and calculating the fundamental effective value and the second harmonic effective value of the three-phase differential current of the excitation transformer using the Fourier algorithm based on the three-phase differential current of the excitation transformer;

[0044] In step (2), the fundamental effective value of the generator rotor voltage is calculated using the Fourier algorithm based on the generator rotor voltage;

[0045] In step (2), the method for calculating the root mean square effective value of the generator rotor voltage includes:

[0046]

[0047] Among them, U r.M (i) is the current root mean square effective value of the generator rotor voltage; U r (ij) represents the rotor voltage at the previous j points, and N represents the number of sampling points in one power frequency cycle.

[0048] In some embodiments, the method for calculating the ratio of the maximum effective value of the second harmonic to the maximum effective value of the fundamental wave in step (3) of the excitation transformer includes:

[0049]

[0050] Where K1 is the ratio of the maximum effective value of the second harmonic to the maximum effective value of the fundamental harmonic of the three-phase differential current of the excitation transformer; I dA.2ω I dB.2ω I dC.2ω I represents the effective value of the second harmonic of the three-phase differential current of the excitation transformer. dA.1ω I dB.1ω I dC.1ω This represents the fundamental effective value of the three-phase differential current of the excitation transformer.

[0051] In some embodiments, the method for calculating the ratio of the fundamental effective value to the root mean square effective value of the generator rotor voltage in step (3) includes:

[0052]

[0053] Among them, K r U is the ratio of the fundamental RMS value to the root mean square RMS value of the rotor voltage. r.1ω U is the fundamental effective value of the rotor voltage; r.M This is the root mean square effective value of the rotor voltage.

[0054] In some embodiments, in step (3), the first fixed threshold I d.set The setting is based on 20%-30% of the rated current on the reference side of the excitation transformer, with the second setting threshold K. 1.set The value ranges from 0.1 to 0.15, with the third fixed threshold K. 2.set The value ranges from 0.5 to 0.7.

[0055] In some embodiments, in step (4), the delay t is 0.1s-5s.

[0056] Furthermore, the fault criterion for the loss of trigger pulses in the rectifier bridge of the excitation system is as follows:

[0057] [max(I dA .1ω,I dB .1ω,I dC.1 ω)>I d.set ]&&(K1>K 1.set )&&(K2>K 2.set )

[0058] Among them, I dA.1ω I dB.1ω I dC.1ω I represents the fundamental effective value of the three-phase differential current of the excitation transformer. d.set The first setting threshold is set at 20%-30% of the rated current on the reference side of the excitation transformer; K1 is the ratio of the maximum effective value of the second harmonic of the three-phase differential current of the excitation transformer to the maximum effective value of the fundamental harmonic; K1.set The second setting threshold is set at 10%-15%; K2 is the ratio of the fundamental effective value to the root mean square effective value of the generator rotor voltage; K 2.set The third threshold is set at 50%-70%.

[0059] Example 2

[0060] Secondly, this embodiment provides a fault detection device for the loss of trigger pulses in the rectifier bridge of an excitation system, including a processor and a storage medium;

[0061] The storage medium is used to store instructions;

[0062] The processor is configured to operate according to the instructions to perform the steps of the method according to Embodiment 1.

[0063] Example 3

[0064] Thirdly, this embodiment provides a storage medium on which a computer program is stored, which, when executed by a processor, implements the steps of the method described in Embodiment 1.

[0065] Example 4

[0066] Fourthly, the present invention provides a computing device, comprising:

[0067] One or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing any of the methods described in Embodiment 1.

[0068] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0069] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0070] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0071] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0072] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for identifying a trigger pulse loss fault of a rectifier bridge of an excitation system, characterized in that, The method comprises: Step (1): obtaining the three-phase current on the high-voltage side of the excitation transformer, the three-phase current on the low-voltage side of the excitation transformer and the generator rotor voltage measured by the protection device; Step (2): based on the three-phase current on the high-voltage side of the excitation transformer, the three-phase current on the low-voltage side of the excitation transformer and the generator rotor voltage, calculating the fundamental effective value and the second harmonic effective value of the three-phase differential current of the excitation transformer, and the root mean square effective value and the fundamental effective value of the generator rotor voltage; Step (3): in response to the fundamental effective value of the three-phase differential current of the excitation transformer being greater than a first fixed threshold, the ratio of the maximum value of the second harmonic effective value to the maximum value of the fundamental effective value of the three-phase differential current of the excitation transformer being greater than a second fixed threshold, and the ratio of the fundamental effective value to the root mean square effective value of the generator rotor voltage being greater than a third fixed threshold, determining that the excitation system rectifier bridge trigger pulse loss fault occurs; Step (4): in response to determining that the excitation system rectifier bridge trigger pulse loss fault occurs, after a delay t, the protection device is operated to alarm.

2. The method of claim 1, wherein the method further comprises: determining whether the trigger pulse is lost based on the comparison. In the step (1), the three-phase current on the high-voltage side of the excitation transformer, the three-phase current on the low-voltage side of the excitation transformer and the generator rotor voltage measured by the protection device are respectively from the current transformer on the high-voltage side of the excitation transformer, the current transformer on the low-voltage side of the excitation transformer and the positive and negative terminals of the rotor winding.

3. The method of claim 1, wherein the method further comprises: determining whether the trigger pulse is lost based on the comparison of the first and second voltage signals. In the step (2), the calculation method of the fundamental effective value and the second harmonic effective value of the three-phase differential current of the excitation transformer comprises: obtaining the three-phase differential current of the excitation transformer according to the three-phase current on the high-voltage side of the excitation transformer and the three-phase current on the low-voltage side of the excitation transformer, and calculating the fundamental effective value and the second harmonic effective value of the three-phase differential current of the excitation transformer according to the three-phase differential current of the excitation transformer by using the Fourier algorithm; And / or, the fundamental effective value of the generator rotor voltage is calculated according to the generator rotor voltage by using the Fourier algorithm; And / or, in the step (2), the calculation method of the root mean square effective value of the generator rotor voltage comprises: where U r.M (i) is the current root mean square value of the generator rotor voltage; U r (i-j) is the rotor voltage at the previous j point in time, and N is the number of sampling points in one power frequency cycle.

4. The method of claim 1, wherein the method further comprises: determining whether the trigger pulse is lost based on the comparison of the first and second voltage signals. In the step (3), the calculation method of the ratio of the maximum value of the second harmonic effective value to the maximum value of the fundamental effective value of the three-phase differential current of the excitation transformer comprises: wherein K1 is the ratio of the maximum value of the second harmonic effective value of the three-phase differential current of the field transformer to the maximum value of the fundamental effective value; I dA.2ω , dB.2ω , I dC.2ω is the second harmonic effective value of the three-phase differential current of the field transformer. dA.1ω , dB.1ω , I dC.1ω is the fundamental effective value of the three-phase differential current of the field transformer.

5. The method of claim 1, wherein the method further comprises: determining whether the trigger pulse is lost based on the comparison of the first and second voltage signals. In the step (3), the calculation method of the ratio of the fundamental effective value to the root mean square effective value of the generator rotor voltage comprises: wherein K r is the ratio of the fundamental effective value to the root-mean-square effective value of the rotor voltage; U r.1ω is the fundamental effective value of the rotor voltage; U r.M is the root-mean-square effective value of the rotor voltage.

6. The method of claim 1, wherein the method further comprises: determining whether the trigger pulse is lost based on the comparison of the first and second voltage signals. In the step (3), the first fixed threshold I dset The second fixed threshold K is set at 20%-30% of the rated current of the transformer base side 1.set The third fixed threshold K is set at 0.1-0.15 2.set The fourth fixed threshold K is set at 0.5-0.

7.

7. The method of claim 1, wherein the method further comprises: determining whether the trigger pulse is lost based on the comparison of the first and second voltage signals. In the step (4), the delay t is 0.1s-5s.

8. A device for discriminating a trigger pulse loss fault of a rectifier bridge of an excitation system, characterized by, The method comprises a processor and a storage medium. The storage medium is used to store instructions. The processor is used to operate according to the instructions to perform the steps of the method according to any one of claims 1 to 7.

9. A storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to implement the steps of the method according to any one of claims 1 to 7.

10. A computing device, comprising: The method comprises: one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs comprise instructions for executing any one of the methods according to claims 1 to 7.

Images