Work condition identification and information reconstruction method and system under ct disconnection anomaly, and medium

Abstract

The application discloses a CT disconnection abnormality under working condition identification and information reconstruction method and system and a medium, and belongs to the field of power system relay protection. The method comprises the following steps: S1, when the current differential protection of an electrical element of a transformer substation is operated, collecting three-phase current information of all outgoing line measuring points of the electrical element; S2, judging whether there is a measuring point satisfying a CT disconnection abnormality working condition identification criterion among all outgoing line measuring points of the electrical element, if there is, determining that the measuring point is abnormal, and executing S3; S3, locking the on-site layer protection of the electrical element. The method further comprises reconstructing the current of the abnormal measuring point by using the currents of the remaining measuring points of the element directly connected with the abnormal measuring point, and realizing fault isolation based on the current of the information-reconstructed measuring point. The application can identify the abnormal working condition of the measuring information under the condition that the original CT disconnection criterion is invalid and the light-load current is small, lock the missing measuring information point to avoid the misoperation of the protection device, and reconstruct the abnormal information to lock the fault position and remove the fault.

Description

Technical Field

[0001] This invention belongs to the field of power system relay protection, and more specifically, relates to a method, system and medium for identifying operating conditions and reconstructing information under CT disconnection anomaly. Background Technology

[0002] Current transformers (CTs) are crucial electrical components in power systems, used for secondary equipment to obtain current information from the primary circuit. However, due to the complexity of the CT secondary circuit, abnormal operating conditions such as CT secondary circuit disconnection are not uncommon in power systems.

[0003] For relay protection devices, if a current transformer (CT) disconnection occurs and the CT disconnection criterion fails, the CT sampling signal cannot accurately reflect the branch current information, thereby increasing the risk of false tripping of the current differential protection. Existing protection devices primarily rely on differential current for CT disconnection alarm criteria. For lightly loaded systems, the load current is very small, and the current in the line will be even smaller when a CT disconnection occurs. Therefore, relying on existing differential current criteria is insufficient to accurately determine the CT disconnection anomaly. Furthermore, after identifying abnormal operating conditions, existing technologies typically employ complex algorithms to reconstruct missing information; these reconstruction methods are complex and lack versatility. Summary of the Invention

[0004] In view of the shortcomings of the existing technology and the need for improvement, the present invention provides a method, system and medium for identifying the working condition and reconstructing information under CT disconnection abnormality, the purpose of which is to realize the judgment of CT disconnection abnormality of electrical components in light load system.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for identifying working conditions and reconstructing information under CT ligation anomalies is provided, comprising:

[0006] S1. When the current differential protection of the electrical components of the substation operates, the three-phase current information of all outgoing measuring points of the electrical components is collected.

[0007] S2. Determine whether there is a measurement point k among all the measurement points of the electrical component that meets the identification criterion for CT disconnection abnormal working condition. If so, determine that measurement point k is abnormal and proceed to S3. The identification criterion for CT disconnection abnormal working condition is:

[0008]

[0009] In the formula, I kx I ky I kz These represent the three-phase currents at the measuring point k, respectively; I set This represents the unbalanced current value of an electrical component under normal operating conditions.

[0010] S3. Lock out the local layer protection of the electrical components.

[0011] Furthermore, it also includes the information reconstruction step:

[0012] S4. Reconstruct the current information of the measuring point k based on the current information of element 1 and element 2 directly connected to the measuring point k: I k1 and I k2 ;in:

[0013]

[0014] In the formula, i takes the value 1 or 2, representing the directly connected element 1 and element 2 connected to the measuring point k, respectively; I ki The current information at measurement point k is reconstructed based on element i; m is the set of measurement point numbers other than measurement point k; I ij The current at all outgoing lines connected to element i, except for measurement point k.

[0015] Furthermore, it also includes fault isolation steps:

[0016] S5. Current information at measurement point k reconstructed using component 1. k1 Replace the original current information at measuring point k, and determine whether the differential protection on component 2 meets the differential current criterion. If it does, execute S6.

[0017] Or / and the current information I at measurement point k reconstructed using element number 2 k2 Replace the original current information at measuring point k, and determine whether the differential protection on component 1 meets the differential current criterion. If it does, execute S6.

[0018] S6. Send a trip command to the circuit breaker at the common connection point k of the two components.

[0019] Furthermore, the differential current criterion is as follows:

[0020]

[0021] Among them: I j Let I be the current at the j-th measuring point of the component, and n be the number of measuring points of the component. M This is the setpoint for differential current operation.

[0022] Furthermore, it also includes the following steps:

[0023] S7. Based on the current of all outgoing measurement points of element 1, determine whether the differential protection on element 1 meets the differential current criterion. If it does, proceed to S9; otherwise, proceed to S8.

[0024] S8. Based on the current of all outgoing measurement points of element 2, determine whether the differential protection on element 2 meets the differential current criterion. If it does, execute S10; otherwise, end the fault investigation process.

[0025] S9. Send a trip command to the circuit breaker connected to component 1 to end the fault investigation process;

[0026] S10. Send a trip command to the circuit breaker connected to component 2 to end the fault investigation process.

[0027] Furthermore, the electrical components of the substation include busbars, transformers, or lines.

[0028] Furthermore, in the CT disconnection abnormality identification criteria, I set =0.06I n I n This is the rated current value.

[0029] According to another aspect of the present invention, a system for identifying working conditions and reconstructing information under CT suture disconnection anomalies is provided, comprising:

[0030] The information acquisition module is used to collect the three-phase current information of all outgoing measuring points of the electrical components when the current differential protection of the electrical components in the substation is activated.

[0031] The measurement point anomaly judgment module is used to determine whether there is a measurement point k among all the measurement points of the electrical component that meets the identification criteria for CT disconnection anomaly. If it exists, the measurement point k is determined to be abnormal, and S3 is executed; wherein, the identification criteria for CT disconnection anomaly is:

[0032]

[0033] In the formula, I kx I ky I kz These represent the three-phase currents at the measuring point k, respectively; I set This represents the unbalanced current value of an electrical component under normal operating conditions.

[0034] A latching module is used to latch the local layer protection of the electrical components.

[0035] Furthermore, it also includes an information reconstruction module, used to reconstruct the current information of the measuring point k based on the current information of element 1 and element 2 directly connected to the measuring point k: I k1 and I k2 ;in:

[0036]

[0037] In the formula, i takes the value 1 or 2, representing the directly connected element 1 and element 2 connected to the measuring point k, respectively; I ki The current information at measurement point k is reconstructed based on element i; m is the set of measurement point numbers other than measurement point k; I ij The current at all outgoing lines connected to element i, except for measurement point k.

[0038] According to another aspect of the invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the method as described in any of the first aspects.

[0039] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0040] (1) The method of the present invention collects the outgoing current measurement information of electrical components that meet the start-up criteria, and makes fault judgment based on the specific fault current characteristics under the fault scenario. When one phase of the three-phase current is lower than the unbalanced current value of the electrical component under normal operation, and two phase currents are greater than the unbalanced current value of the electrical component under normal operation, it is determined that the electrical component has lost measurement information. This criterion does not depend on the differential current signal, and can accurately identify the abnormal working condition of CT disconnection and lock the abnormal measurement point when the system light load current is small and the original CT disconnection criterion fails, so as to avoid the protection device from malfunctioning due to the collection of incorrect measurement information.

[0041] (2) Furthermore, the method of the present invention can also reconstruct abnormal measurement point information by utilizing the redundant information of the remaining measurement points of the components directly connected to the abnormal measurement point in the scenario of missing measurement information. It does not require complex algorithm implementation, and the method is simple and highly versatile.

[0042] (3) Furthermore, based on the current information of measurement point k after information reconstruction, the method of the present invention can also achieve fault isolation. The current information of measurement point k reconstructed using element 1 I k1 Replace the original current information at measurement point k with the differential current criterion used on component 2 to determine if a fault exists; or use the reconstructed current information I at measurement point k from component 2. k2 By replacing the current information of the original measuring point k and using the differential current criterion on element 1 to determine whether there is a fault, it can be determined whether the fault is on element 1 or / and element 2 which are directly connected to the abnormal measuring point, thus locking the scope of fault isolation. Then, the differential current criterion is used to specifically determine whether the fault is on element 1 or element 2, thereby achieving fault isolation.

[0043] (4) The method of the present invention is applicable to the identification and isolation of faults in busbars, transformers or lines, with few limitations and a wide range of applications.

[0044] (5) As a preferred option, I set =0.06I n I n The rated current value enables accurate identification of abnormal CT disconnection conditions under light load and low current, while also eliminating the possibility of criterion failure caused by unbalanced current. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the method for identifying and reconstructing information under abnormal CT lumbar disc herniation provided by the present invention.

[0046] Figure 2 The flowchart of the working condition identification and information reconstruction method under CT line breakage abnormality provided by the present invention is shown.

[0047] Figure 3 This is a schematic diagram of a power system provided for an embodiment of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0049] like Figure 1 , Figure 2 As shown, the method for identifying working conditions and reconstructing information under CT suture breakage anomalies of the present invention mainly includes the following steps:

[0050] S1. When the differential current protection of an electrical component in a power system substation operates, the three-phase current information of all outgoing measuring points of the electrical component is collected. In this embodiment of the invention, the three-phase current information of all outgoing measuring points of the electrical component is collected through the information module of the substation area protection device. In other embodiments, other substation protection systems can also be used to collect the corresponding information. The substation electrical components include busbars, transformers, or lines.

[0051] S2. Determine whether there is a measurement point k among all the measurement points of the electrical component that meets the identification criteria for CT disconnection abnormal condition. If so, determine that measurement point k is abnormal and proceed to S3. The identification criteria for CT disconnection abnormal condition are:

[0052]

[0053] In the formula, I kx I ky I kzRepresent the three-phase currents at measuring point k that satisfy the identification criteria for abnormal CT disconnection conditions; I set The current criterion setting represents the unbalanced current value of an electrical component under normal operating conditions. In this embodiment of the invention, I is taken as... set =0.06I n I n The rated current value of measuring point k under rated operating conditions.

[0054] S3. Lock out the local layer protection of this electrical component.

[0055] Since the above-mentioned CT disconnection abnormal condition identification criterion is based on the specific fault current characteristics under fault scenarios, when one phase of the three-phase current is lower than the unbalanced current value of the electrical component under normal operating conditions, and two phase currents are greater than the unbalanced current value of the electrical component under normal operating conditions, it is determined that the electrical component has a missing measurement information, that is, a CT disconnection abnormality has occurred. This criterion does not rely on differential current signals and can accurately identify the abnormal condition of missing measurement information and lock the measurement point with missing measurement information when the system is under light load and the original CT disconnection criterion fails, thus avoiding the protection device from malfunctioning due to the collection of incorrect measurement information.

[0056] Based on the abnormal operating condition identification in steps S1-S3 above, the method of the present invention further includes an information reconstruction step:

[0057] S4. Reconstruct the current information of measuring point k based on the current information of the two components directly connected to measuring point k (denoted as component 1 and component 2): I k1 and I k2 ;in:

[0058]

[0059] In the formula, i takes the value 1 or 2, representing the directly connected element 1 and element 2 connected to the measuring point k, respectively; I ki The current information at measurement point k is reconstructed based on element i; m is the set of measurement point numbers other than measurement point k; I ij The current at all outgoing lines connected to element i, except for measurement point k.

[0060] Based on the current information at measurement point k reconstructed from the above information, the method of the present invention further includes a fault isolation step:

[0061] S5. Current information at measurement point k reconstructed using component 1. k1Replace the current information at the original measuring point k, and use the differential current criterion on element 2 to determine if there is a fault. That is, determine whether the differential protection on element 2 meets the differential current criterion. If the differential current criterion is met, it means that there is a fault on element 1 or / and element 2, and execute S6; otherwise, directly end the fault investigation process.

[0062] Or / and the current information I at measurement point k reconstructed using element number 2 k2 Replace the original current information at measurement point k, and use the differential current criterion on component 1 to determine if there is a fault;

[0063] The differential current criterion is as follows:

[0064]

[0065] Among them: I j Let I be the current at the j-th measuring point of the component. When using the differential current criterion to determine whether a fault exists on component number 2, I... j Let I be the current at the j-th measuring point of component 2. When using the differential current criterion on component 1 to determine if a fault exists, I... j I represents the current at the j-th measuring point of component 1; n represents the number of measuring points of the component; M This is the setpoint for differential current operation.

[0066] S6. Send a trip command to the circuit breaker at the common connection point k of the two components.

[0067] S7. Based on the current of all outgoing measurement points of element 1, determine whether the differential protection on element 1 meets the differential current criterion. If the differential current criterion is met, it indicates that there is a fault on element 1, and proceed to S9; otherwise, proceed to S8.

[0068] S8. Based on the current of all outgoing measurement points of element 2, determine whether the differential protection on element 2 meets the differential current criterion. If the differential current criterion is met, it indicates that there is a fault on element 2, and execute S10; otherwise, directly end the fault investigation process.

[0069] S9. Send a trip command to the circuit breaker connected to component 1 to end the fault investigation process;

[0070] S10. Send a trip command to the circuit breaker connected to component 2 to end the fault investigation process.

[0071] To facilitate understanding of the present invention, the method of the present invention will be further explained and described below with specific embodiments.

[0072] like Figure 3 As shown, assuming Figure 3A phase-a CT disconnection anomaly occurs at measuring point a, and a phase-a ground fault F1 occurs on line ab. At this time, the local protection device between line ab and the 220kV bus I of station A, or the station-area protection device of station A, detects that the differential current protection of line ab (i.e., element 1) and 220kV bus I of station A (i.e., element 2) meets the tripping conditions. Collect all current measurement information of the two elements of line ab and 220kV bus I of station A (i.e.,... Figure 3 The measurement information of the three-phase current at each of the measurement points (c, d, a, and b) is substituted into the CT disconnection abnormal condition identification criterion in this invention. The three-phase current at measurement point a is determined to satisfy the CT disconnection abnormal condition identification criterion. Measurement point a is identified as a CT disconnection abnormal measurement point, indicating a CT disconnection in phase a. Local protection of the ab line and the 220kV busbar I at station A is blocked to prevent false tripping.

[0073] The station area device obtains the current information of measuring point a reconstructed by two components, I, from the ab line and the 220kV busbar I of station A, respectively: I a1 and I a2 The station domain device will I a1 After the reconstructed current replaces the original current at measuring point a, the differential current criterion of the 220kV bus I at station A is used for judgment, and the station area device will I. a2 After the reconstructed current replaces the original current at measuring point a, the differential current criterion of the ab line is used for judgment. When the local current differential protection criterion of one of the components meets the operating conditions, the station protection sends a trip command to the circuit breaker at measuring point a. If the circuit breaker at measuring point a is detected to be open, then the local current differential protection criterion of the two components is used to judge the current at all outgoing measuring points of the ab line and the 220kV bus I of station A, respectively, and the fault is investigated and isolated according to S7-S10.

[0074] According to another aspect of the present invention, an abnormal operating condition identification and information reconstruction system for addressing missing measurement information is provided, comprising:

[0075] The information acquisition module is used to collect three-phase current information from all outgoing measuring points of the electrical components when the differential current protection of the electrical components in the substation operates.

[0076] The measurement point anomaly judgment module is used to determine whether there is a measurement point k among all the measurement points of the electrical component that meets the identification criteria for CT disconnection anomaly. If it exists, the measurement point k is determined to be abnormal, and S3 is executed. The identification criteria for CT disconnection anomaly are as follows:

[0077]

[0078] In the formula, I kx I ky I kzThese represent the three-phase currents at measuring point k, respectively; I set This represents the unbalanced current value of an electrical component under normal operating conditions.

[0079] A locking module is used to lock the local layer protection of electrical components.

[0080] Furthermore, it also includes an information reconstruction module, used to reconstruct the current information of measuring point k based on the current information of components 1 and 2 directly connected to measuring point k: I k1 and I k2 ;in:

[0081]

[0082] In the formula, i takes the value 1 or 2, representing the directly connected element 1 and element 2 connected to the measuring point k, respectively; I ki I represents the current information at measurement point k reconstructed from component i; m is the set of measurement point numbers excluding k; I ij The current at all outgoing lines connected to element i, except for measurement point k.

[0083] Each module is used to perform the corresponding steps in the above-mentioned method for identifying and reconstructing abnormal operating conditions in response to missing measurement information.

[0084] According to another aspect of the present invention, a computer-readable storage medium is also provided, on which a computer program is stored, which, when executed by a processor, implements each step of the above-described method for identifying and reconstructing abnormal operating conditions in response to missing measurement information.

[0085] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for identifying working conditions and reconstructing information under CT suture anomalies, characterized in that, include: S1. When the current differential protection of the electrical components of the substation operates, the three-phase current information of all outgoing measuring points of the electrical components is collected. S2. Determine whether there is a measurement point k among all the measurement points of the electrical component that meets the identification criterion for CT disconnection abnormal working condition. If so, determine that measurement point k is abnormal and proceed to S3. The identification criterion for CT disconnection abnormal working condition is: In the formula, I kx , I ky , I kz These represent the three-phase currents at the measuring point k, respectively. I set This represents the unbalanced current value of an electrical component under normal operating conditions. S3. Lock out the local layer protection of the electrical components; It also includes the information reconstruction step: S4. Reconstruct the current information of the measuring point k based on the current information of element 1 and element 2 directly connected to the measuring point k: I k1 and I k2 ;in: In the formula, i Take 1 or 2, which respectively represent the 1st and 2nd components directly connected to the measuring point k; I ki According to i The current information of measurement point k reconstructed by component number; m is the set of measurement point numbers other than measurement point k; I ij To and i The current at all outgoing lines connected to component number excluding measuring point k; It also includes fault isolation steps: S5. Current information at measurement point k reconstructed using component 1. k1 Replace the original current information at measuring point k, and determine whether the differential protection on component 2 meets the differential current criterion. If it does, execute S6. Or / and the current information I at measurement point k reconstructed using element number 2 k2 Replace the original current information at measuring point k, and determine whether the differential protection on component 1 meets the differential current criterion. If it does, execute S6. S6. Send a trip command to the circuit breaker at the common connection point k of the two components. It also includes the following steps: S7. Based on the current of all outgoing measurement points of element 1, determine whether the differential protection on element 1 meets the differential current criterion. If it does, proceed to S9; otherwise, proceed to S8. S8. Based on the current of all outgoing measurement points of element 2, determine whether the differential protection on element 2 meets the differential current criterion. If it does, execute S10; otherwise, end the fault investigation process. S9. Send a trip command to the circuit breaker connected to component 1 to end the fault investigation process; S10. Send a trip command to the circuit breaker connected to component 2 to end the fault investigation process.

2. The method according to claim 1, characterized in that, The differential current criterion is: in: I j For the first component j The current at each measuring point, where n is the number of measuring points on the component. I M This is the setpoint for differential current operation.

3. The method according to claim 1, characterized in that, The electrical components of the substation include busbars, transformers, or lines.

4. The method according to claim 1, characterized in that, The CT disconnection abnormality identification criteria are as follows: I set = 0.06I n , I n The rated current value of measuring point k under rated operating conditions.

5. A system for identifying working conditions and reconstructing information under abnormal CT suture lines, characterized in that, The system for identifying and reconstructing operational conditions under CT line breakage anomalies, as described in any one of claims 1-4, comprises: The information acquisition module is used to collect the three-phase current information of all outgoing measuring points of the electrical components when the current differential protection of the electrical components in the substation is activated. The measurement point anomaly judgment module is used to determine whether there is a measurement point k among all the measurement points of the electrical component that meets the identification criteria for CT disconnection anomaly. If it exists, the measurement point k is determined to be abnormal, and S3 is executed; wherein, the identification criteria for CT disconnection anomaly is: In the formula, I kx , I ky , I kz These represent the three-phase currents at the measuring point k, respectively. I set This represents the unbalanced current value of an electrical component under normal operating conditions. A locking module is used to lock the local layer protection of the electrical components; It also includes an information reconstruction module, used to reconstruct the current information of the measuring point k based on the current information of element 1 and element 2 directly connected to the measuring point k: I k1 and I k2 ;in: In the formula, i Take 1 or 2, which respectively represent the 1st and 2nd components directly connected to the measuring point k; I ki According to i The current information of measurement point k reconstructed by component number; m is the set of measurement point numbers other than measurement point k; I ij To and i The current at all outgoing lines connected to component number 1, except for measuring point k.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the method as described in any one of claims 1-4.

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