KR-102959833-B1 - APPARATUS FOR DIAGNOSING CABLE TANGENT DELTA CONDITION

Abstract

An apparatus and method for predicting the tan delta of a cable are disclosed. An apparatus for predicting the tan delta of a cable according to one aspect of the present invention comprises a communication interface, a memory in which relational information regarding prediction coefficients according to the tan delta standard deviation is stored, and a processor connected to the communication interface and the memory. The processor receives a first tan delta and a first tan delta standard deviation, which are the results of an ultra-low frequency tan delta test for a cable performed under a first voltage condition, through the communication interface, detects a prediction coefficient corresponding to the first tan delta standard deviation from the relational information stored in the memory, and applies the detected prediction coefficient to the first tan delta to predict a second tan delta, which is the tan delta of the cable under a second voltage condition.

Inventors

• 장병한
• 송민규
• 김명동

Assignees

• 한국전력공사

Dates

Publication Date

20260508

Application Date

20250522

Claims (1)

1. Communication interface; A memory storing relationship information regarding prediction coefficients based on tan delta standard deviations; and It includes the above communication interface and a processor connected to the above memory, The processor receives a first tan delta and a first tan delta standard deviation, which are the results of an ultra-low frequency tan delta test for a cable performed under a first voltage condition, through the communication interface, detects a prediction coefficient corresponding to the first tan delta standard deviation from relation information stored in the memory, and applies the detected prediction coefficient to the first tan delta to predict a second tan delta, which is the tan delta of the cable under a second voltage condition. The above-mentioned memory stores the above-mentioned relationship information for each tan delta level interval, and The processor determines a tan delta level interval based on the first tan delta, detects the prediction coefficient from relationship information corresponding to the determined tan delta level interval, and A cable tan delta state diagnosis device characterized by the processor collecting diagnostic result data of an ultra-low frequency tan delta test through the communication interface and calculating the relationship information for each tan delta level section based on the collected diagnostic result data.

Description

Apparatus for Diagnosing Cable Tangent Delta Condition The present invention relates to an apparatus and method for predicting the tan delta of a cable, and more specifically, to an apparatus and method for predicting the tan delta of a cable under relatively high voltage conditions from information regarding the tan delta of a cable measured under relatively low voltage conditions. Very Low Frequency Tangent Delta (VLF TD) diagnosis is a method of diagnosing the degree of cable degradation by applying a very low frequency power source to a cable, measuring the tan delta—the deviation between leakage current and voltage—and using the measured tan delta. Meanwhile, if a voltage higher than the system voltage is applied to the cable during VLF TD diagnosis, insulation breakdown may occur, and the cable's lifespan may be reduced due to the stress applied during VLF TD diagnosis. Accordingly, there is a need for technology capable of performing VLF TD diagnosis at low voltages. The background technology of the present invention is disclosed in Korean Published Patent Application No. 10-2022-0116965 (August 23, 2022). FIG. 1 is a block diagram showing a tan delta prediction device for a cable according to one embodiment of the present invention. FIG. 2 is a first flowchart showing a method for predicting the tan delta of a cable according to one embodiment of the present invention. FIG. 3 is an exemplary diagram showing relationship information according to one embodiment of the present invention. FIG. 4 is a second flowchart showing a method for predicting the tan delta of a cable according to one embodiment of the present invention. Figure 5 is an example diagram showing the Weibull distribution regarding tan delta according to diagnostic voltage. Figure 6 is an example diagram showing the results of analyzing the correlation between the tan delta standard deviation and the tan delta. FIGS. 7a and 7b are exemplary diagrams showing the accuracy of a cable tan delta prediction method according to an embodiment of the present invention. Hereinafter, a device and method for predicting the tan delta of a cable according to an embodiment of the present invention will be described in detail with reference to the attached drawings. In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of explanation. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intention or convention of the user or operator. Therefore, the definitions of these terms should be based on the content throughout this specification. FIG. 1 is a block diagram showing a tan delta prediction device for a cable according to one embodiment of the present invention. Referring to FIG. 1, a tan delta prediction device for a cable according to one embodiment of the present invention may include a communication interface (100), a memory (200), and a processor (300). Each component included in the tan delta prediction device for a cable according to one embodiment of the present invention may be connected and communicate via a bus. Each component may be connected via an individual interface or an individual bus centered on the processor (300), rather than a common bus. The tan delta prediction device for a cable according to one embodiment of the present invention may include various additional components in addition to the components shown in FIG. 1, or may omit some of the above components. The communication interface (100) can communicate with an external device. The communication interface (100) can communicate with various types of external devices according to various types of communication methods. Various information required during the operation of the processor (300) may be stored in the memory (200). Relational information regarding prediction coefficients based on the tan delta standard deviation (stdev, standard deviation) may be stored in advance in the memory (200). Here, the prediction coefficient may refer to a conversion coefficient used to convert the tan delta (Tan δ, dielectric loss tangent) of the cable measured under a first voltage condition into the tan delta under a second voltage condition. The tan delta standard deviation may refer to the standard deviation of several (e.g., 8) tan deltas measured through a Very Low Frequency Tangent Delta test (VLF TD test). Here, the first voltage condition may correspond to 1 Uo (13.2 kV), and the second voltage condition may correspond to 1.5 Uo (17.5 kV). That is, the prediction coefficient may correspond to a conversion coefficient for predicting the tan delta when 1.5 Uo is applied to the cable from the tan delta measured when 1 Uo is applied to the cable. The processor (300) can be operatively connected to the communication interface (100) and the memory (200). The processor (300) can be implemented as a Central Processing U