A current transformer disconnection fault positioning processing method and system

Abstract

The application discloses a kind of current transformer wire breakage fault positioning processing method and system, method includes: in protection device, additional redundant current transformer;With current mutation variable, real-time calculation N line and current amplitude and N line and current mutation variable amplitude;Set criterion, judge N line and current amplitude whether greater than flow threshold value, identify whether the stable CT wire breakage occurs outside protection device;And, judge N line and current mutation variable amplitude whether greater than mutation variable threshold, identify whether the intermittent CT wire breakage occurs outside protection device;According to the discrimination condition of conventional differential protection CT wire breakage, and in combination with criterion distinguishes wire breakage position, again in combination with three-phase CT sampling balance and distinguish result, determine the phase of specific CT wire breakage and position.The application has less demand to hardware resource, can distinguish whether CT wire breakage occurs in device CT primary side or secondary side, and according to fault position, provide corresponding processing mode.Improves the reliability of differential protection.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a method and system for locating and handling faults caused by open circuits in current transformers. Background Technology

[0002] The open circuit detection function of the CT circuit is an important component of relay protection. Relay protection technical regulations all require that the protection device should issue an open circuit signal when the current circuit is broken, allowing the differential protection to trip. However, relevant regulations have not provided guidance on whether to distinguish between a secondary-side open circuit and a primary-side open circuit in the internal CT, and how to resolve this. This function is also not found in devices from major protection manufacturers. A differential protection CT open circuit can occur on either the primary or secondary side of the CT. If it occurs on the primary side, it may generate high voltage, in which case the differential protection can trip. However, if it occurs on the secondary side, allowing the differential protection to trip is inappropriate.

[0003] Current conventional CT disconnection criteria vary among manufacturers, with typical criteria including: for internal faults, at least one of the following conditions must be met: the negative sequence phase voltage on any side is greater than 2V; the current in any phase on any side increases after startup compared to before startup; the maximum phase current after startup is greater than 1.2Ie; and three currents simultaneously decrease compared to before startup. However, none of these conditions are met when a CT disconnects. Existing technologies do not consider differentiating the location of the disconnection. Considering the possibility of internal CT disconnections and cold solder joints occurring during field operation, it is necessary to study CT disconnection fault location and subsequent handling methods. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the aforementioned existing problems, this invention is proposed. Therefore, this invention provides a method for locating and handling faults caused by open circuits in current transformers. This addresses the problems of noise inherent in barometers, the tendency for excessively small relative height difference update thresholds to accumulate static deviations, resulting in abnormally large climb values ​​even in static conditions, and the potential for complete neglect of climb values ​​during actual activities such as mountain climbing due to ups and downs.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a method for locating and handling faults of current transformer open circuits, comprising: adding redundant current transformers to the protection device, wherein the redundant current transformers collect the secondary neutral point and current of the N line of all differential CTs;

[0008] Calculate the current change Δ Real-time calculation of N-line and current amplitude And the magnitude of the N-line and the current surge Δ ;

[0009] Set criteria to determine the neutral line and current amplitude. Whether it exceeds the current threshold value, identify whether a stable CT disconnection has occurred outside the protection device; and determine the amplitude Δ of the neutral line and the current surge. Whether the value exceeds the mutation threshold, identify whether intermittent CT line disconnection occurs outside the protection device;

[0010] Based on the conventional differential protection CT disconnection criteria, and combined with the aforementioned criteria to distinguish the disconnection location, and further combined with the three-phase CT sampling balance and the aforementioned distinction results, the specific phase and location of the CT disconnection are determined.

[0011] As a preferred embodiment of the current transformer open circuit fault location and handling method described in this invention, the addition of redundant current transformers includes,

[0012] The sum of the neutral currents (N-line currents) of all differential CTs within the newly added CT acquisition cabinet;

[0013] The current sent by the through-heart CT is collected using the current transformer on the device side.

[0014] As a preferred embodiment of the current transformer open circuit fault location and handling method described in this invention, the addition of redundant current transformers includes,

[0015] The protection panel cabinet is uniformly grounded, while the neutral (N) line of the CT terminal box is not grounded. The device's CT collects the sum of the neutral (N) line currents of all differential CTs.

[0016] As a preferred embodiment of the current transformer open circuit fault location and handling method described in this invention, wherein: the current change Δ is calculated. , is represented as:

[0017] Δ =

[0018] in, Indicates the current sampling point. These are the sampling points two electrical cycles prior, where N is the number of points per cycle.

[0019] Real-time calculation of N-line and current amplitude , is represented as:

[0020] ;

[0021] N-line and current abrupt change amplitude Δ , is represented as:

[0022] .

[0023] As a preferred embodiment of the current transformer open-circuit fault location and processing method of the present invention, wherein: the current threshold value is set to, ;

[0024] The first criterion is set as follows:

[0025]

[0026] In the formula, I n For the rated current of the current-carrying device CT, This represents the sum of the maximum unbalanced zero-sequence currents of each group of CTs during normal operation of the unit, determined by the device at 0.25P. n 0.5P n 0.75P n P n The N-line and current at the four operating points are automatically adjusted to the maximum value, P n The rated power of the unit, This is the minimum value of the secondary rated current of each group of differential CTs;

[0027] It also includes setting a second criterion to limit the criterion conditions, expressed as:

[0028]

[0029] In the formula, U n I is the rated secondary voltage of the generator. e This is the generator's secondary rated current.

[0030] In a preferred embodiment of the current transformer open circuit fault location and processing method of the present invention, the sudden change threshold is expressed as: A third criterion is set, namely:

[0031]

[0032] The discrimination result is widened by 30ms.

[0033] As a preferred embodiment of the current transformer open circuit fault location processing method of the present invention, the method includes: determining the open circuit location based on the conventional differential protection CT open circuit identification and in conjunction with the criteria, including:

[0034] When the conventional differential protection CT disconnection criterion has already determined the disconnection, if the first criterion and the second criterion are satisfied at the same time, or if the second criterion and the third criterion are satisfied at the same time, then it is determined that the primary side of the device CT is disconnected. The disconnection range includes the primary side of the device CT, the device to the cabinet, and the cabinet to the CT terminal box.

[0035] If the first criterion and the third criterion do not meet the discrimination conditions, but the second criterion meets the discrimination conditions, then it is determined that the device CT secondary side is disconnected, and the disconnection range includes the device CT secondary side and the AD sampling conditioning circuit.

[0036] Based on the three-phase CT sampling balance and the aforementioned differentiation results, the specific phase and location of the CT line break are determined, including:

[0037] If the differential protection is locked on the secondary side of the CT in the device, an abnormality in the device's sampling circuit will be reported.

[0038] If a CT disconnection is reported on the primary side of the device, it should be handled according to the setting value for whether the differential circuit is locked due to the CT disconnection.

[0039] Secondly, the present invention provides an apparatus for locating and processing open-circuit faults in current transformers, comprising,

[0040] The acquisition module is used to add redundant current transformers in the protection device. The redundant current transformers acquire the secondary neutral point and current of the N line of all differential CTs.

[0041] The calculation module is used to calculate the current abrupt change Δ. Real-time calculation of N-line and current amplitude And the magnitude of the N-line and the current surge Δ ;

[0042] The first identification module is used to set criteria to determine the neutral line and current amplitude. Whether it exceeds the current threshold value, identify whether a stable CT disconnection has occurred outside the protection device; and determine the amplitude Δ of the neutral line and the current surge. Whether the value exceeds the mutation threshold, identify whether intermittent CT line disconnection occurs outside the protection device;

[0043] The second identification module is used to determine the phase and location of the CT breakage based on the judgment of the conventional differential protection CT breakage and the judgment criteria, and then to determine the specific CT breakage phase and location by combining the three-phase CT sampling balance and the judgment results.

[0044] Thirdly, the present invention provides a computing device, comprising:

[0045] Memory and processor;

[0046] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the current transformer open circuit fault location and processing method.

[0047] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the current transformer open circuit fault location processing method.

[0048] Compared with existing technologies, the beneficial effects of this invention are as follows: This method, applied to protection devices, uses redundant CTs to sample the secondary neutral points and currents of all differential CTs, and determines the status of the current channel in real time. It requires fewer hardware resources, can distinguish whether a CT disconnection occurs on the primary or secondary side of the CT, and provides corresponding handling methods based on the fault location. This improves the reliability of differential protection and provides more detailed CT disconnection locations, facilitating maintenance personnel in troubleshooting. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0050] Figure 1 This is a schematic diagram of the overall process of the current transformer open circuit fault location and processing method according to an embodiment of the present invention;

[0051] Figure 2 This is a schematic diagram of the through-core CT + device CT acquiring the N line and current in the current transformer open circuit fault location and processing method according to an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the CT device acquiring the N line and current in the current transformer open circuit fault location and processing method according to an embodiment of the present invention;

[0053] Figure 4 This is a logic block diagram of the primary side open circuit identification device CT in the current transformer open circuit fault location and processing method according to an embodiment of the present invention;

[0054] Figure 5 This is a logic block diagram for identifying open circuit on the secondary side of the current transformer (CT) in a current transformer open circuit fault location and processing method according to an embodiment of the present invention. Detailed Implementation

[0055] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0056] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0057] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0058] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0059] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0060] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0061] Example 1

[0062] Reference Figure 1-5As an embodiment of the present invention, a method for locating and handling faults in a current transformer open circuit is provided, comprising:

[0063] S1: Add redundant current transformers to the protection device. The redundant current transformers collect the secondary neutral point and current of the N line of all differential CTs.

[0064] As one possible implementation method, such as Figure 2 Adding redundant current transformers can,

[0065] The sum of the neutral currents (N-line currents) of all differential CTs within the newly added CT acquisition cabinet;

[0066] The current sent by the through-heart CT is collected using the current transformer on the device side.

[0067] It should be noted that this method does not require any changes to the existing grounding method of the N line in the CT terminal box.

[0068] As one possible implementation method, such as Figure 3 Adding redundant current transformers can also provide...

[0069] The protection panel cabinet is uniformly grounded, while the neutral (N) line of the CT terminal box is not grounded. The device's CT collects the sum of the neutral (N) line currents of all differential CTs.

[0070] It should be noted that this method requires very little modification to the hardware circuit, but it does require changing the grounding method of the N line in the original CT terminal box.

[0071] S2: Calculation of current surge Δ Real-time calculation of N-line and current amplitude And the magnitude of the N-line and the current surge Δ ;

[0072] Furthermore, the calculation and current mutation Δ , is represented as:

[0073] Δ =

[0074] in, Indicates the current sampling point. These are the sampling points two electrical cycles prior, where N is the number of points per cycle.

[0075] Real-time calculation of N-line and current amplitude , is represented as:

[0076] ;

[0077] N-line and current abrupt change amplitude Δ , is represented as:

[0078] .

[0079] S3: Set criteria to determine the neutral line and current amplitude. Whether it exceeds the current threshold value, identify whether a stable CT disconnection has occurred outside the protection device; and determine the amplitude Δ of the neutral line and the current surge. Whether the value exceeds the mutation threshold, identify whether intermittent CT line disconnection occurs outside the protection device;

[0080] Furthermore, the flow threshold is set to, ;

[0081] The first criterion is set as follows:

[0082]

[0083] In the formula, I n For the rated current of the current-carrying device CT, This represents the sum of the maximum unbalanced zero-sequence currents of each group of CTs during normal operation of the unit, determined by the device at 0.25P. n 0.5P n 0.75P n P n The N-line and current at the four operating points are automatically adjusted to the maximum value, P n The rated power of the unit, This is the minimum value of the secondary rated current of each group of differential CTs;

[0084] It also includes setting a second criterion to limit the criterion conditions, expressed as:

[0085]

[0086] In the formula, U n I is the rated secondary voltage of the generator. e This is the generator's secondary rated current.

[0087] It should be noted that the purpose of setting the second criterion is to limit the criterion operating conditions while avoiding interference from external faults.

[0088] Furthermore, the mutation threshold is expressed as: A third criterion is set, namely:

[0089]

[0090] The discrimination result is widened by 30ms.

[0091] It should be noted that the first criterion is set to judge the neutral line and the current amplitude. Whether it exceeds the current threshold is used to identify whether a stable CT disconnection has occurred outside the protection device; a third criterion is set to judge the amplitude Δ of the neutral line and the current surge. Whether the value exceeds the threshold for sudden change is used to identify whether intermittent CT disconnection occurs outside the protection device. Given that the conventional differential protection CT disconnection criterion has already identified a CT disconnection, the first and third criteria can identify all external CT disconnections. To ensure the reliability of the criteria and eliminate interference from primary-side faults, a second criterion is set to ensure that CT disconnection fault location processing is performed under normal system operating conditions.

[0092] The decision result is extended by 30ms because the third criterion is a change criterion. When the line breaks, the fault characteristics of the criterion only last for a very short time, existing from normal operation to the moment of line breakage. After the line breaks, the change between two power frequency cycles will return to zero. The result is extended by 30ms to ensure that the device has a stable processing time window.

[0093] S4: Based on the judgment of the conventional differential protection CT disconnection, and combined with the criteria to distinguish the disconnection location, and combined with the three-phase CT sampling balance and the distinction results, determine the specific phase and location of the CT disconnection.

[0094] Furthermore, such as Figure 4 As shown, when the conventional differential protection CT disconnection criterion has already determined the disconnection, if the first criterion and the second criterion simultaneously meet the discrimination conditions, or if the second criterion and the third criterion simultaneously meet the discrimination conditions, then it is determined that the primary side of the device CT is disconnected. The disconnection range includes the primary side of the device CT, the device to the cabinet, and the cabinet to the CT terminal box.

[0095] like Figure 5 As shown, if the first criterion and the third criterion do not meet the discrimination conditions, but the second criterion meets the discrimination conditions, then it is determined that the device CT secondary side is disconnected, and the disconnection range includes the device CT secondary side and the AD sampling conditioning circuit.

[0096] Based on the three-phase CT sampling balance and differentiation results, the specific phase and location of the CT line break are determined, including,

[0097] Specifically, the sampling balance of the three-phase CT is determined by identifying the phase with the smallest current as the broken phase. This is combined with the identification of broken wires on the primary and secondary sides of the CT to ultimately determine the specific phase and location of the broken wire.

[0098] If the differential protection is locked on the secondary side of the CT in the device, an abnormality in the device's sampling circuit will be reported.

[0099] If a CT disconnection is reported on the primary side of the device, it should be handled according to the setting value for whether the differential circuit is locked due to the CT disconnection.

[0100] The above is a schematic scheme of a current transformer open circuit fault location and processing method according to this embodiment. It should be noted that the technical solution of the current transformer open circuit fault location and processing device belongs to the same concept as the technical solution of the current transformer open circuit fault location and processing method described above. For details not described in detail in the technical solution of the current transformer open circuit fault location and processing push device in this embodiment, please refer to the description of the technical solution of the current transformer open circuit fault location and processing push method described above.

[0101] The current transformer open circuit fault location and processing system in this embodiment includes:

[0102] The acquisition module is used to add redundant current transformers in the protection device. The redundant current transformers acquire the secondary neutral point and current of the N line of all differential CTs.

[0103] The calculation module is used to calculate the current surge Δ. Real-time calculation of N-line and current amplitude And the magnitude of the N-line and the current surge Δ ;

[0104] The first identification module is used to set criteria to determine the neutral line and current amplitude. Whether it exceeds the current threshold value, identify whether a stable CT disconnection has occurred outside the protection device; and determine the amplitude Δ of the neutral line and the current surge. Whether the value exceeds the mutation threshold, identify whether intermittent CT line disconnection occurs outside the protection device;

[0105] The second identification module is used to determine the phase and location of the CT breakage based on the judgment of the conventional differential protection CT breakage and the criteria for distinguishing the breakage location. It also combines the three-phase CT sampling balance and the distinction results to determine the specific CT breakage phase and location.

[0106] This embodiment also provides a computing device applicable to the location and handling of current transformer open circuit faults, including:

[0107] The system includes a memory and a processor. The memory stores computer-executable instructions, and the processor executes these instructions to implement the current transformer open-circuit fault location and handling method proposed in the above embodiments.

[0108] This embodiment also provides a storage medium storing a computer program, which, when executed by a processor, implements the current transformer open circuit fault location processing method proposed in the above embodiments.

[0109] The storage medium proposed in this embodiment and the method for locating and handling current transformer open circuit faults proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0110] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0111] Example 2

[0112] Referring to Table 1, an embodiment of the present invention provides a method for locating and handling faults caused by open circuits in current transformers. To verify its beneficial effects, a comparison of two schemes is provided.

[0113] Table 1 Comparison of Schemes

[0114] plan CT line breakage detection speed Disconnection location identification function Is there a possibility that a fault in the device's data acquisition circuit could cause the differential protection to malfunction? Traditional solution Within 30ms Not supported exist This invention Within 28ms support Does not exist

[0115] The typical criteria for traditional solutions are as follows:

[0116] In the event of an internal failure, at least one of the following conditions must be met:

[0117] (1) The negative sequence phase voltage on either side is greater than 2V;

[0118] (2) After startup, the current in any phase on any side increases compared to before startup;

[0119] (3) The maximum phase current after startup is greater than 1.2Ie;

[0120] (4) At the same time, the current in three circuits is reduced compared to before startup.

[0121] When the CT disconnects, none of the above conditions are met. Therefore, if none of the above conditions are met within 40ms after the differential protection is activated, it is judged as a CT disconnection. If the "CT disconnection blocking ratio differential activation" is set to 1 at this time, the differential protection is blocked and a differential CT disconnection alarm signal is issued. If the control word is set to 0, the differential protection operates at the output and a differential CT disconnection alarm signal is issued at the same time.

[0122] Our solution addresses the difficulty in distinguishing between primary and secondary side disconnections in the CT (Clipper Detector) system. Existing CT disconnection criteria, based on current CT systems, cannot differentiate whether a CT disconnection occurs on the primary or secondary side after acquiring differential current data from each side.

[0123] Therefore, this invention adds a redundant CT to collect the secondary neutral point and current of all differential CTs. If the secondary side of the device CT is disconnected, the redundant CT will not have any current; if the primary side of the device CT is disconnected, the redundant CT will have a significantly increased current. Therefore, the scheme of collecting the secondary neutral point and current of all differential CTs based on the redundant CT can identify whether the disconnection occurs on the primary or secondary side of the device CT.

[0124] Based on the data in Table 1, the broken wires are further divided into stable broken wires and intermittent short-term CT broken wires. For stable broken wires, the full-wave Fourier algorithm is used for identification, and for intermittent broken wires, the half-wave Fourier algorithm is used for discrimination, thereby improving the applicability of the protection criteria.

[0125] Finally, after identifying the specific location of the disconnection, the protection handling method is given: if it is on the secondary side of the device CT, the differential protection is blocked and the device sampling circuit is reported as abnormal; if it is on the primary side of the device CT, the CT disconnection is reported and the handling is carried out according to the setting value of whether the differential protection is blocked when the CT disconnection is in the setting value, which improves the reliability of the differential protection.

[0126] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for locating and handling faults caused by open circuits in current transformers, characterized in that, include: A redundant current transformer is added to the protection device, and the redundant current transformer collects the secondary neutral point and current of the N line of all differential CTs. Calculate the current change Δ Real-time calculation of N-line and current amplitude And the magnitude of the N-line and the current surge Δ ; The criteria are set, with the first criterion being the determination of the neutral line and the current amplitude. Whether it exceeds the current threshold value, it identifies whether a stable CT disconnection has occurred outside the protection device; the third criterion is to judge the amplitude Δ of the neutral line and the current surge. Whether the value exceeds the threshold of sudden change, it identifies whether intermittent CT disconnection occurs outside the protection device; and the second criterion is to limit the criterion operating conditions, eliminate the interference of primary side faults on the disconnection criterion, and ensure that the CT disconnection fault location processing is carried out under the normal operating conditions of the system. Based on the conventional differential protection CT line breakage identification, and combined with the aforementioned criteria to distinguish the breakage location, and further combined with the three-phase CT sampling balance and the aforementioned distinction results, the specific phase and location of the CT line breakage are determined, including: When the conventional differential protection CT disconnection criterion has already determined the disconnection, if the first criterion and the second criterion are satisfied at the same time, or if the second criterion and the third criterion are satisfied at the same time, then it is determined that the primary side of the device CT is disconnected. The disconnection range includes the primary side of the device CT, the device to the cabinet, and the cabinet to the CT terminal box. If the first criterion and the third criterion do not meet the discrimination conditions, but the second criterion meets the discrimination conditions, then it is determined that the device CT secondary side is disconnected, and the disconnection range includes the device CT secondary side and the AD sampling conditioning circuit. Based on the three-phase CT sampling balance and the aforementioned differentiation results, the specific phase and location of the CT line break are determined, including: If the differential protection is locked on the secondary side of the CT in the device, an abnormality in the device's sampling circuit will be reported. If a CT disconnection is reported on the primary side of the device, it should be handled according to the setting value for whether the differential circuit is locked due to the CT disconnection.

2. The method for locating and handling open-circuit faults in current transformers as described in claim 1, characterized in that, The addition of redundant current transformers includes... The sum of the neutral currents (N-line currents) of all differential CTs within the newly added CT acquisition cabinet; The current sent by the through-heart CT is collected using the current transformer on the device side.

3. The method for locating and handling open-circuit faults in current transformers as described in claim 2, characterized in that, The addition of redundant current transformers includes... The protection panel cabinet is uniformly grounded, while the neutral (N) line of the CT terminal box is not grounded. The device's CT collects the sum of the neutral (N) line currents of all differential CTs.

4. The method for locating and handling open-circuit faults in current transformers as described in claim 3, characterized in that, Calculate the current change Δ , is represented as: D = in, Indicates the current sampling point. These are the sampling points two electrical cycles prior, where N is the number of points per cycle. Real-time calculation of N-line and current amplitude , is represented as: ； N-line and current abrupt change amplitude Δ , is represented as: 。 5. The method for locating and handling open-circuit faults in current transformers as described in claim 4, characterized in that, The flow threshold value is set to, ; The first criterion is set as follows: In the formula, I n For the rated current of the current-carrying device CT, This represents the sum of the maximum unbalanced zero-sequence currents of each group of CTs during normal operation of the unit, determined by the device at 0.25P. n 0.5P n 0.75P n P n The N-line and current at the four operating points are automatically adjusted to the maximum value, P n The rated power of the unit, This is the minimum value of the secondary rated current of each group of differential CTs; It also includes setting a second criterion to limit the criterion conditions, expressed as: In the formula, U n I is the rated secondary voltage of the generator. e This is the generator's secondary rated current.

6. The method for locating and handling open-circuit faults in current transformers as described in claim 5, characterized in that, The mutation threshold is expressed as: A third criterion is set, namely: The discrimination result is widened by 30ms.

7. A current transformer open-circuit fault location and processing system, using the method described in any one of claims 1-6, characterized in that, include, The acquisition module is used to add redundant current transformers in the protection device. The redundant current transformers acquire the secondary neutral point and current of the N line of all differential CTs. The calculation module is used to calculate the current abrupt change Δ. Real-time calculation of N-line and current amplitude And the magnitude of the N-line and the current surge Δ ; The first identification module is used to set criteria to determine the neutral line and current amplitude. Whether it exceeds the current threshold value, identify whether a stable CT disconnection has occurred outside the protection device; and determine the amplitude Δ of the neutral line and the current surge. Whether the value exceeds the mutation threshold, identify whether intermittent CT line disconnection occurs outside the protection device; The second identification module is used to determine the phase and location of the CT breakage based on the judgment of the conventional differential protection CT breakage and the judgment criteria, and then to determine the specific CT breakage phase and location by combining the three-phase CT sampling balance and the judgment results.

8. An electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the current transformer open circuit fault location processing method according to any one of claims 1 to 6.

9. A computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the current transformer open-circuit fault location processing method according to any one of claims 1 to 6.

Images