KR101984432B1 - Diagnosis device for monitoring degradation of cable and diagnosis method thereof - Google Patents

Abstract

The present invention relates to an apparatus and method for diagnosing a deterioration state of a cable that can detect a deterioration state in real time by detecting a voltage and a leakage current applied to the cable and calculating a leakage resistance and a capacitance value for each section of the cable.
For example, a detection step of detecting a voltage and a leakage current applied to a cable; Calculating a leakage resistance and a capacitance of each section of the cable by substituting the voltage and the leakage current detected in the detecting step into the degradation diagnosis algorithm; And a storage determining step of storing the calculated value in each of the sections in real time and determining that the section corresponding to the calculated value deviates from the reference range if the calculated value is out of the reference range. A method of diagnosing a deteriorated state of a cable is disclosed.

Description

[0001] The present invention relates to a cable deterioration diagnosis apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for diagnosing a deterioration state of a cable.

Generally, power cables such as power transmission lines are buried underground, so they are relatively safe because they are not exposed to the natural environment. However, once an accident occurs in such a cable, it is difficult to detect and repair the fault point, and it takes a long time to recover, so that the power failure time becomes longer and the recovery cost is increased. Further, in order to diagnose the insulation deterioration state of the cable, the state of the cable is diagnosed in a diagonal state by periodically performing a power interruption, resulting in a large maintenance cost.

The present invention relates to a cable deterioration state diagnostic apparatus capable of detecting a voltage and a leakage current applied to a cable and calculating a leakage resistance, a capacitance, a dielectric loss tangent, and a dielectric loss value for each section of the cable, Provides a diagnostic method.

A method for diagnosing a deterioration state of a cable according to the present invention includes: detecting a voltage and a leakage current applied to a cable; Calculating a leakage resistance and a capacitance of each section of the cable by substituting the voltage and the leakage current detected in the detecting step into the degradation diagnosis algorithm; And a storage determining step of storing the calculated value in each of the sections in real time and determining that the section corresponding to the calculated value deviates from the reference range if the calculated value is out of the reference range. do.

Wherein the cable includes a first section, a second section and a third section in sequence between a power transmission end and a power reception end, and the leakage resistance (r ₁ ) of the first section is calculated by the following equation,

The capacitance (c ₁ ) of the first section is calculated by the following equation,

The dielectric tangent (tan? ₁ ) of the first section is calculated by the following equation,

The dielectric loss (W ₁ ) of the first section is calculated by the following equation,

Wherein, Y ₁ is the admittance of the first section, θ ₁ is a phase difference between the first voltage and the starting point of the leakage current _{section, ΔI 1 = (I 11 ∠θI} 11 -I 12 ∠θI 12) and, θΔI ₁ = θI ₁₁ - θI be ₁₂ days.

The admittance (Y ₁ ) of the first section is calculated by the following equation,

Here, I ₁₁ is the starting point current of the first section, and I I ₁₁ Is the phase angle of the I _11, I ₁₂ is the first section end point current, θI ₁₂ Is the phase angle of I ₁₂ , V _d1 is the starting point voltage of the first section _{,? Vd1} Can represent the phase angle of V _d1 .

The start voltage (V _d1) of the first section is identical to the transmission-circuit voltage _{(V S), V d1 ∠θ} Vd1 = V _S ∠ 慮_Vs.

The leakage resistance (r ₂ ) of the second section is calculated by the following equation,

The capacitance (c ₂ ) of the second section is calculated by the following equation,

The dielectric tangent (tan? ₂ ) of the second section is calculated by the following equation,

The dielectric loss (W ₂ ) of the second section is calculated by the following equation,

Here, Y ₂ is the admittance of the second interval, θ ₂ is a phase difference between the second voltage and the starting point of the leakage current _{section, ΔI 2 = (I 21 ∠θI} 21 -I 22 ∠θI 22) and, θΔI ₂ = θI ₂₁ - θI be ₂₂ days.

The admittance (Y ₂ ) of the second section is calculated by the following equation,

Here, I is the starting point ₂₁ of the second current interval, θI ₂₁ Is the phase angle of the I _21, I ₂₂ is the second section end point current, θI ₂₂ Is a phase angle of ₂₂ I, V _d2 is the start voltage of the second period, θ _vd2 It may represent the phase angle of V _d2.

The starting point voltage V _d2 of the second section is calculated by the following equation,

Here, V _S is the transmission terminal voltage,? _Vs is the phase angle of V _S , Vr is the receiver front end voltage,? _Vr is the phase angle of Vr, d is the total cable length, and d ₁ is the length of the first section .

The leakage resistance (r ₃ ) of the third section is calculated by the following equation,

The capacitance (c ₃ ) of the third section is calculated by the following equation,

The dielectric tangent (tan? ₃ ) of the third section is calculated by the following equation,

The dielectric loss (W ₃ ) in the third section is calculated by the following equation,

Wherein, Y ₃ is the admittance of the third section, θ ₃ is the phase difference between the third voltage and the starting point of the leakage current _{section, ΔI 3 = (I 31 ∠θI} 31 -I 32 ∠θI 32) and, θΔI ₃ = θI ₃₁ - θI may be ₃₂ days.

The admittance (Y ₃ ) of the third section is calculated by the following equation,

Here, I ₃₁ is the starting point current of the third section, and I I ₃₁ The phase angle of I ₃₁ , I ₃₂ the end point current of the third section, and I I ₃₂ Is a phase angle of ₃₂ I, V _d3 is the start voltage of the third period, θ _vd3 Can represent the phase angle of V _d3 .

The starting point voltage V _d3 of the third section is calculated by the following equation,

Here, V _S is a transmission-circuit voltage, θ _Vs is the phase angle of V _S, Vr is the front end voltage, θ _Vr is the phase angle of Vr, d cable full length, d ₁ is the length of the first interval, d ₂ is The length of the second section can be indicated.

The apparatus and method for diagnosing a deterioration state of a cable according to an embodiment of the present invention detect a voltage and a leakage current applied to a cable and calculate leakage resistance, capacitance, dielectric loss tangent and dielectric loss value for each section of the cable, Thus, the deterioration state of each section of the cable can be determined in real time. Accordingly, the apparatus and method for diagnosing a deteriorated state of a cable according to the present invention can reduce deterioration measurement time and cost, and can improve the safety of a cable.

1 is a block diagram showing an apparatus for diagnosing a deterioration state of a cable according to an embodiment of the present invention.
2 is a cross-sectional view of the cable.
3 is a schematic diagram showing an apparatus for diagnosing a deterioration state of a cable according to an embodiment of the present invention.
4 is a schematic circuit diagram showing a state in which a diagnostic device according to an embodiment of the present invention is installed in a three-phase cable used in a transmission line.
5 is a schematic circuit diagram showing a state in which a diagnostic apparatus according to an embodiment of the present invention is installed in a single-phase cable.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, The present invention is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more faithful and complete, and will fully convey the scope of the invention to those skilled in the art.

1 is a block diagram showing an apparatus for diagnosing a deterioration state of a cable according to an embodiment of the present invention. 2 is a cross-sectional view of the cable. 3 is a schematic diagram showing an apparatus for diagnosing a deterioration state of a cable according to an embodiment of the present invention.

1 to 3, an apparatus 100 for diagnosing a deterioration state of a cable according to an embodiment of the present invention includes a detection unit 110, an operation unit 120, a storage determination unit 130, and a signal output unit 140, .

Here, the cable 10 refers to a power cable used for a transmission line, a distribution line, a wiring of an electric device, an indoor wiring, and the like. 2, the cable 10 includes a core wire conductor 11 formed at the center, an insulation layer 12 surrounding the core wire conductor 11, and a sheath (not shown) for protecting the insulation layer 12 13). The core wire conductor 11 may be made of a conductive material through which a current can flow, for example, a metal such as copper or aluminum, and may be a wire with a single wire or a plurality of wire strands. The insulating layer 12 is for electrical insulation of the cable 10, and may be made of, for example, a polymer resin. The diameter of the core wire conductor 11 can be appropriately selected depending on the capacity of the cable 10 and the thickness of the insulation layer 12 can be appropriately selected by the voltage of the cable 10. [ The sheath 13 may be made of metal, and may be grounded by a cross-bond grounding system, a both-end grounding system, or a one-end grounding system. As shown in FIG. 3, the cable 10 has a connecting point for connecting the cables 10 to each other at a predetermined distance, and the cable 10 can be divided into a plurality of sections based on the connecting point.

The detection unit 110 detects in real time the voltage applied to the cable 10 to diagnose deterioration and the leakage current. At this time, the detection unit 110 can detect a voltage and a current in a state where the cable 10 is used. The detecting unit 110 may include a transformer 111 (PT: Potential Transform) capable of detecting a voltage and an output voltage applied to the cable 10. Also, the detecting unit 110 may include a current transformer 112 (CT) capable of detecting the current of the cable 10. The current transformer 112 is installed between the respective sections (connection points) of the cable 10, and can measure the current between the sections. For example, as shown in FIG. 4, the current transformers 112 may exist in pairs in each section. Specifically, CT ₁₁ and CT ₁₂ of the current transformer of the first section, CT ₂₁ and CT ₂₂ of the current transformer of the second section, CT ₃₁ and CT ₃₂ of the current transformer of the third section, respectively. Here, the voltage value between each section of the cable 10 can be calculated using the voltage value measured through the transformer 111. [ The current and voltage detected by the detecting unit 110 are transmitted to the calculating unit 120.

The calculation unit 120 substitutes the current and voltage detected by the detection unit 110 for the degradation diagnosis algorithm and calculates the leakage resistance and the capacitance value for each section of the cable 10. These algorithms will be described in more detail below. Also, the calculating unit 120 may calculate the dielectric dissipation factor (tan?) And the dielectric loss (W) using the leakage resistance and the capacitance value.

The storage determination unit 130 stores leakage resistance and capacitance values in real time for each section of the cable 10 calculated by the calculation unit 120 and analyzes the stored values to determine the deterioration state. Specifically, the storage determination unit 130 may determine that deterioration has occurred if the measured leakage resistance and capacitance change values are out of the reference range. Here, values for the reference range of the leakage resistance and the capacitance value for each section are stored in advance in the storage determination unit 130.

The signal output unit 140 outputs a signal according to the determination result of the storage determination unit 130. For example, when the storage determination unit 130 determines that the leakage resistance or the capacitance value of the cable 10 is out of the reference range, the signal output unit 140 generates an alarm and simultaneously outputs a leakage resistance or a capacitance value An interval beyond the reference range can be displayed. For example, the signal output unit 140 may be a display device such as a monitor. Therefore, the user can easily find the deteriorated section in the cable 10, and can easily recover. In addition, the signal output unit 140 may display the dielectric loss tangent and the dielectric loss value to inform the user. For example, it can be seen that the lower the dielectric loss tangent value displayed on the signal output unit 140 is, the better the insulation state of the user, and the higher the degree of deterioration is, the higher the user is.

Next, a method of diagnosing deterioration of a cable according to an apparatus for diagnosing a deterioration state of a cable according to an embodiment of the present invention will be described.

4 is a schematic circuit diagram showing a state in which a diagnostic device according to an embodiment of the present invention is installed in a three-phase cable used in a transmission line. 5 is a schematic circuit diagram showing a state in which a diagnostic apparatus according to an embodiment of the present invention is installed in a single-phase cable.

As shown in FIG. 4, the apparatus for diagnosing a deterioration state of a cable according to an embodiment of the present invention can measure the insulation state of a three-phase cable like a transmission line. On the other hand, the method for measuring the insulation state of the three-phase cable or the single-phase cable is the same, and therefore, for convenience of explanation, a method of measuring the insulation state of the single-phase cable will be described as shown in Fig.

As shown in FIG. 5, the cable 10 has a transmission terminal and a reception terminal, and is divided into a first section, a second section, and a third section. Of course, the cable 10 may be divided into more sections, but in the present invention, the cable 10 is divided into three sections.

In Figure 5 the transmission terminal voltage Vs, Vr is the front end voltage, V _d1 is the starting point of the first voltage range, V _d2 is the starting point of the second voltage range, V _d3 represents the start voltage of the third period. In addition, I ₁₁ is the start current of the first section, I ₁₂ the end current of the second interval, I ₂₁ is the starting point of the second period current, I ₂₂ is the second section end point current, I ₃₁ is the starting point of the third region Current, and I ₃₂ represents the end-point current of the third section. In addition, C ₁ denotes a first section capacitance, C ₂ denotes a second section capacitance, C ₃ denotes a third section capacitance, r ₁ denotes a first section leakage resistance, r ₂ denotes a second section leakage resistance, r ₃ denotes a third section Leakage resistance. In addition, all of the cable the distance d, the first time period the distance d _1, the second time period the distance d _2, the third section is a distance d _3.

First, the algorithm for detecting deterioration of the first section of the cable 10 in the calculator 120 is calculated according to the following equations ( ₁ ) to ( ₃ ), and finally the capacitance (c ₁ ) and The leakage resistance r ₁ can be obtained.

Here, Y ₁ is the first section admittance, and? I ₁₁ It is the phase angle of the I _11, θI ₁₂ Is the phase angle of I ₁₂ , and? _Vd1 V _d1 Respectively. And _{also, V d1 = V S, V} d1 ∠θ Vd1 = V _S ?? _Vs to be.

From the above equation (1), the following equations (2) and (3) can be derived.

Here,? ₁ represents the phase difference between the starting point voltage of the first section and the leakage current.

In addition, the leakage resistance (r ₁ ) of the first section can be obtained from the above equation (2).

In addition, the capacitance (c ₁ ) of the first section can be obtained from Equation (3).

The calculation unit 120 can obtain the dielectric loss tangent tan? ₁ of the first section and the dielectric loss W ₁ from the leakage resistance r ₁ and the capacitance c ₁ .

Here, ΔI ₁ = (I ₁₁ ∠θI ₁₁ -I ₁₂ ∠θI ₁₂ ) and θΔI ₁ = θI ₁₁ -θI ₁₂ .

Next, the algorithm for detecting deterioration of the second section of the cable 10 in the calculator 120 is calculated according to the following equations (4) to (6), and finally the capacitance c ₂ of the second section And the leakage resistance (r ₂ ) can be obtained.

Here, Y ₂ is the second section admittance, and? I ₂₁ It is the phase angle of the I _21, θI ₂₂ It is a phase angle of ₂₂ I, θ _vd2 V _d2 Respectively. Further, the starting point voltage V _d2 of the second section can be obtained as follows with reference to FIG.

Here, Vs is a voltage at the transmission end, Vr is a voltage at the front end, and? _Vs It is the phase angle of V _s, θ _{Vr Represents} the phase angle of V _r .

From Equation (4), the following Equations (5) and (6) can be derived.

Here,? ₂ represents the phase difference between the starting point voltage of the second section and the leakage current.

In addition, the leakage resistance r _{2 in} the second section can be obtained from the above equation (5).

In addition, the capacitance c ₂ of the second section can be obtained from the equation (6).

Also, the calculation unit 120 can obtain the dielectric loss tangent tan ( ₂ ) and the dielectric loss (W ₂ ) of the second section from the leakage resistance (r ₂ ) and the capacitance (c ₂ ).

Here, the _{ΔI 2 = (I 21 ∠θI 21} -I 22 ∠θI 22) _{and, θΔI 2 = θI 21 -θI 22} .

Next, the algorithm for detecting deterioration of the third section of the cable 10 in the calculator 120 is calculated according to the following equations (7) to (9), and finally the capacitance c3 and The leakage resistance r ₃ can be obtained.

Here, Y ₃ is the third section admittance, and? I ₃₁ Is the phase angle of I ₃₁ , &thetas; I ₃₂ It is a phase angle of ₃₂ I, θ _vd3 V _d3 Respectively. Further, the starting point voltage V _d3 of the third section can be obtained as follows with reference to FIG.

Here, Vs is a voltage at the transmission end, Vr is a voltage at the front end, and? _Vs It is the phase angle of V _s, θ _{Vr Represents} the phase angle of V _r .

From Equation (7), the following Equations (8) and (9) can be derived.

Here,? ₃ represents the phase difference between the starting point voltage of the third section and the leakage current.

From equation (8), the leakage resistance (r ₃ ) of the third section can be obtained.

In addition, the capacitance c _{3 in} the third section can be obtained from the above equation (9).

In addition, the computing unit 120 may obtain the leakage resistance (r ₃₎ and the capacitance dielectric loss tangent (tanδ ₃₎ and dielectric loss (W ₃₎ of the third section from (c _3).

Here, ΔI ₃ = (I ₃₁ ∠θI ₃₁ -I ₃₂ ∠θI ₃₂ ), and θΔI ₃ = θI ₃₁ -θI ₃₂ .

The apparatus and method for diagnosing a deterioration state of a cable according to an embodiment of the present invention detect a voltage and a leakage current applied to a cable in real time to detect leakage resistance, capacitance, dielectric loss tangent, and dielectric loss And the deterioration state of each section of the cable can be determined in real time. Accordingly, the apparatus and method for diagnosing a deteriorated state of a cable according to the present invention can reduce deterioration measurement time and cost, and can improve the safety of a cable.

It is to be understood that the present invention is not limited to the above-described embodiment, and that various modifications and changes may be made by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

10: Cable
110:
120:
130:
140: Signal output section

Claims (11)

A detecting step of detecting a voltage and a leakage current applied to the cable;
Calculating a leakage resistance and a capacitance of each section of the cable by substituting the voltage and the leakage current detected in the detecting step into the degradation diagnosis algorithm; And
And a storage determination step of storing the calculated value in each of the sections in real time and determining that the section corresponding to the calculated value deviates from the reference range when the calculated value is out of the reference range,
The cable includes a first section, a second section and a third section in sequence between a transmission end and a reception end,
The leakage resistance (r ₁ ) of the first section is calculated by the following equation,

The capacitance (c ₁ ) of the first section is calculated by the following equation,

The dielectric tangent (tan? ₁ ) of the first section is calculated by the following equation,

The dielectric loss (W ₁ ) of the first section is calculated by the following equation,

Wherein, Y ₁ is the admittance of the first section, θ ₁ is a phase difference between the first voltage and the starting point of the leakage current _{section, ΔI 1 = (I 11 ∠θI} 11 -I 12 ∠θI 12) and, θΔI ₁ = θI ₁₁ - degradation diagnostic method of the cable, characterized in that θI _12. delete The method according to claim 1,
The admittance (Y ₁ ) of the first section is calculated by the following equation,

Here, I ₁₁ is the phase angle, I ₁₂ is the phase angle, V _d1 of the end point current, θI ₁₂ of the first section is I ₁₂ is the starting point the voltage of the first period of the first period starting point for the current, θI ₁₁ is I _11, the θ is _vd1 degradation diagnostic method of the cable, characterized in that represents the phase angle of V _d1. The method of claim 3,
The starting point voltage V _d1 of the first section is equal to the transmission terminal voltage V _S ,
V _d1 = V _S ∠θ _Vd1 ∠θ degradation diagnostic method of the cable, characterized in that _Vs. The method according to claim 1,
The leakage resistance (r ₂ ) of the second section is calculated by the following equation,

The capacitance (c ₂ ) of the second section is calculated by the following equation,

The dielectric tangent (tan? ₂ ) of the second section is calculated by the following equation,

The dielectric loss (W ₂ ) of the second section is calculated by the following equation,

Here, Y ₂ is the admittance of the second interval, θ ₂ is a phase difference between the second voltage and the starting point of the leakage current _{section, ΔI 2 = (I 21 ∠θI} 21 -I 22 ∠θI 22) and, θΔI ₂ = θI ₂₁ - degradation diagnostic method of the cable, characterized in that θI _22. 6. The method of claim 5,
The admittance (Y ₂ ) of the second section is calculated by the following equation,

Here, I is the starting point ₂₁ of the second current interval, θI ₂₁ Is the phase angle of the I _21, I ₂₂ is the second section end point current, θI ₂₂ Is a phase angle of ₂₂ I, V _d2 is the start voltage of the second period, θ _vd2 And the phase angle of the cable is V _d2 . The method according to claim 6,
The starting point voltage V _d2 of the second section is calculated by the following equation,

Here, V _S is a transmission-circuit voltage, θ _Vs is the phase angle of V _S, Vr is the front end voltage, θ _Vr is the phase angle of Vr, d cable full length, d ₁ is characterized by indicating the length of the first section The method comprising the steps of: The method according to claim 1,
The leakage resistance (r ₃ ) of the third section is calculated by the following equation,

The capacitance (c ₃ ) of the third section is calculated by the following equation,

The dielectric tangent (tan? ₃ ) of the third section is calculated by the following equation,

The dielectric loss (W ₃ ) in the third section is calculated by the following equation,

Wherein, Y ₃ is the admittance of the third section, θ ₃ is the phase difference between the third voltage and the starting point of the leakage current _{section, ΔI 3 = (I 31 ∠θI} 31 -I 32 ∠θI 32) and, θΔI ₃ = θI ₃₁ - degradation diagnostic method of the cable, characterized in that θI _32. 9. The method of claim 8,
The admittance (Y ₃ ) of the third section is calculated by the following equation,

Here, I ₃₁ is the starting point current of the third section, and I I ₃₁ The phase angle of I ₃₁ , I ₃₂ the end point current of the third section, and I I ₃₂ Is a phase angle of ₃₂ I, V _d3 is the start voltage of the third period, θ _{vd3 Gt;} a < / RTI > phase angle of V _d3 . 10. The method of claim 9,
The starting point voltage V _d3 of the third section is calculated by the following equation,

Here, V _S is a transmission-circuit voltage, θ _Vs is the phase angle of V _S, Vr is the front end voltage, θ _Vr is the phase angle of Vr, d cable full length, d ₁ is the length of the first interval, d ₂ is And the length of the second section is indicative of the length of the second section. An apparatus for diagnosing a deterioration state of a cable characterized by diagnosing a deterioration state of a cable by the diagnostic method according to any one of claims 1 to 10.

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