CN107976251A - A kind of transmission pressure structure destroys on-line monitoring system and monitoring method - Google Patents

Abstract

An on-line monitoring system for structure damage of transmission wires disclosed in the present invention includes an optical fiber acceleration sensor, an optical signal demodulator, an A/D converter and a microprocessor connected in sequence, the microprocessor is also connected with the wind speed and direction sensor, and the microprocessor The device is also connected with the 3G module and the monitoring center in turn. The system compares the natural frequency of the conductor calculated in the microprocessor with the natural frequency obtained by the modal analysis of the structurally intact conductor by the monitoring center to realize the judgment of the structural damage of the transmission conductor. The invention also discloses a monitoring method for wire structure damage. The specific steps include four steps: modeling and modal analysis of structurally complete wires, processing of acceleration signals, modal analysis based on acceleration signals, and diagnosis of wire structure damage.

Description

An on-line monitoring system and monitoring method for structural damage of transmission wires

technical field

The invention belongs to the technical field of state monitoring and diagnosis of power transmission lines, and in particular relates to an on-line monitoring system for structure damage of power transmission wires, and also relates to a monitoring method using the on-line monitoring system.

Background technique

In the power system, the transmission line is an important part of power transmission, and its safe operation is an important factor to ensure the ability of power transmission. In recent years, with the continuous promotion of ultra-high voltage lines and ultra-high voltage lines, there are more and more long-span transmission lines, and accidents such as broken strands of transmission wires and anti-vibration hammers falling off caused by breeze vibrations cannot be ignored.

Breeze vibration is a phenomenon that exists in all overhead transmission lines. At present, in order to reduce the damage to the transmission wire caused by breeze vibration, research has been done on vibration monitoring, vibration prevention, and wire repair technology at home and abroad, which has played a certain role. Effect. However, the current vibration monitoring of transmission wires is limited to the measurement of vibration characteristic parameters such as the vibration frequency, amplitude, and dynamic bending strain of the wires. Influenced by parameters such as vibration frequency and number of cycles, the overall effect is not ideal.

Contents of the invention

The purpose of the present invention is to provide an on-line monitoring system for structure damage of power transmission wires, which can realize on-line monitoring of broken strands of power transmission wires, falling off of anti-vibration hammers and the like.

The technical solution of the present invention is an on-line monitoring system for the damage of the transmission wire structure, including an optical fiber acceleration sensor, an optical signal demodulator, an A/D converter and a microprocessor connected in sequence, and the microprocessor is also connected with the wind speed and direction sensor , the microprocessor is also connected with the 3G module and the monitoring center in turn.

The present invention is also characterized in that,

The fiber grating acceleration sensor is installed on the transmission wire, and the optical signal demodulator is installed on the transmission tower.

The fiber grating acceleration sensor is connected to the optical signal demodulator through the optical fiber, and the optical signal demodulator is connected to the A/D conversion module through the shielded twisted pair.

The A/D conversion module is connected to the microprocessor through a synchronous serial communication interface; the wind speed and direction sensor is connected to the microprocessor through RS485.

Another object of the present invention is to provide a monitoring method using the on-line monitoring system, which can extract the modal parameters of the transmission wire through the collected vibration signals, as an important basis for judging the change of the wire structure.

Another technical solution of the present invention is a method for monitoring by using the structure of the transmission wire to destroy the online monitoring system, which is specifically implemented according to the following steps:

Step 1, establish a model, and obtain the natural frequency ω ₀ when the wire structure to be detected is normal;

Step 2, collect the actual wind speed and acceleration through the wind speed and direction sensor and the optical fiber acceleration sensor, and calculate the wind speed of the vertical wire;

Step 3, according to the signal collected by the optical fiber acceleration sensor, after processing by the optical signal modulator and A/D conversion module, the time domain signal is processed by the microprocessor, and the natural frequency ω of the wire is obtained by the random subspace analysis method ₁ ;

Step 4, compare the natural frequency ω ₁ measured in step 3 with the natural frequency ω ₀ in the normal state calculated in step 1, and judge the state of the wire structure.

The present invention is also characterized in that,

Step 1 is specifically:

Step 1.1, establish the finite element model of the wire to be diagnosed, which includes hardware such as wire and anti-vibration hammer, wherein the wire is set as a model made of multi-strand steel core and aluminum strands, and cannot be simplified;

Step 1.2, considering the weight of the wire and the anti-vibration hammer, apply wire pretension to the wire in the model, and impose omni-directional constraints on both ends of the wire, conduct modal analysis on the wire in this state, and obtain the wire structure in the normal state The natural frequency ω ₀ under .

Step 2 is specifically to calculate the wind speed v _x of the vertical wire according to the angle θ between the wind direction and the wire,

v _x ＝v×sinθ (1)

Where v _x is the wind speed of the vertical wire, and v is the actual wind speed.

Step 3 is specifically,

Step 3.1, digitally filter the acceleration signal to filter out high-frequency interference signals above 1kHz;

Step 3.2, constructing the processed wire acceleration signal into a Hankel matrix,

Among them, H _{n1, n2} is the Hankel matrix, which is a matrix composed of the covariance of the conductor vibration acceleration signal, R _i represents the covariance, R _i =E[a _i+1 a _i ], and a _i is the conductor vibration at time i Acceleration, E means expectation, the value range of i is: 1≤i≤(n1+n2-1);

The singular value decomposition of the matrix can be decomposed into the following form,

Among them, U ₁ , V ₁ are unitary matrix, ∑ ₁ is singular value matrix

In addition, according to the state space equation of the randomly excited N-degree-of-freedom system, the covariance of the vibration response of the wire at time i can be written as

R _i =A ^i-1 G (4)

Among them, G=E[v _x a _i ], A is the system matrix

Substituting (4) into (2), we can get

From formula (5), we can get,

Among them, according to formula (3) and formula (5), we can get

Substituting (7) and (8) into (6), the system matrix A can be calculated;

Step 3.3, determine the stable mode of the system matrix A calculated in step 3.2, and obtain the eigenvalue μ _k of the system matrix according to formulas (9) and (10), and then obtain the natural frequency ω _i of the wire through the eigenvalues;

Among them, μ _k is the eigenvalue of the system matrix, Im represents the imaginary part, ξ _i represents the damping ratio of the calculated wire, ω _i is the natural frequency of the calculated wire, and represents the natural frequency of the wire calculated from the acceleration signal measured at the i-th moment; λ It is an intermediate quantity introduced during formula derivation;

Step 3.4: Carry out calculations from steps 3.1 to 3.3 on the acceleration signals collected at different times i, and average the results as the measured natural frequency ω ₁ .

Step 4 specifically is to compare the natural frequency ω ₁ measured in step 3 with the natural frequency ω ₀ in the normal state calculated in step 1, when When , it is determined that the wire structure is in an abnormal state, otherwise, when , it is judged that the wire structure is in a normal state.

The beneficial effects of the present invention are:

1. The present invention establishes the finite element model of the transmission wire, and obtains the natural frequency of the wire under the fault-free state through the finite element analysis method, and uses it as a state parameter of the wire structure being intact.

2. In the monitoring center, the finite element model of the transmission wire established by the present invention can change the wire structure parameters, span, fitting type, etc. according to different lines, thereby realizing the calculation of the modal parameters under the normal state of different lines.

3. The present invention adopts the empirical mode decomposition method to analyze the working mode of the transmission wire. The natural frequency of the wire can be analyzed according to the acceleration signal collected by the sensor, and then compared with the modal parameters of the wire in the non-fault state to realize the destruction of the wire structure status diagnostics.

4. The modal analysis model based on the acceleration signal of the present invention is embedded in the microprocessor STM32, and the data sent by the 3G module is the calculated natural frequency, which reduces the calculation workload of the monitoring center.

Description of drawings

Fig. 1 is the overall block diagram of the on-line monitoring system for the damage of the transmission wire structure in the present invention;

Fig. 2 is a flow chart of the wire structure damage diagnosis method in the present invention.

In the figure, 1. Optical fiber acceleration sensor, 2. Optical signal demodulator, 3. A/D converter, 4. Wind speed and direction sensor, 5. Microprocessor, 6.3G communication unit, 7. Monitoring center.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The on-line monitoring system for the damage of the power transmission wire structure of the present invention, as shown in Figure 1, includes an optical fiber acceleration sensor 1, an optical signal demodulator 2, an A/D converter 3 and a microprocessor 5 connected in sequence, and the microprocessor 5 is also connected with the microprocessor 5. Wind speed and direction sensor 4 connection,

The microprocessor 5 is also connected with the 3G module 6 and the monitoring center 7 in turn;

The fiber grating acceleration sensor 1 is installed on the power transmission wire, and is used for measuring the acceleration of the vertical direction of the wire,

The fiber grating acceleration sensor 1 is connected with the optical signal demodulator 2 through an optical fiber,

The optical signal demodulator 2 is installed on the transmission tower;

The optical signal demodulator 2 is connected to the A/D conversion module 3 through a shielded twisted pair;

The A/D conversion module 3 is connected to the microprocessor 5 through a synchronous serial communication interface;

Wind speed and direction sensor 4 is connected to microprocessor 5 by RS485;

The installation and working process of the on-line monitoring system for the structure damage of the power transmission wire of the present invention are as follows: at first the fiber grating acceleration sensor 1 is installed on the power transmission wire, the acceleration in the vertical direction of the wire is measured, and then the optical signal of the fiber grating acceleration sensor 1 is transmitted to the In the optical signal demodulator 2, the optical signal demodulator 2 is installed on the transmission tower, and the optical signal demodulator 2 converts the acceleration optical signal into an acceleration electrical signal analog quantity, and connects to the A/D conversion module through a shielded twisted pair 3 carries out analog-to-digital conversion, and the A/D conversion module 3 connects the digital quantity of the acceleration electric signal after conversion to the microprocessor 5 through a synchronous serial communication interface, and the wind speed and direction sensor 4 transmits the electric signal digital quantity of the wind speed and direction to the Microprocessor 5. Microprocessor 5 uses the received acceleration data and wind speed and direction data to conduct modal analysis of the power transmission line, and finally sends the analyzed natural frequency to the monitoring center 7 through the 3G module 6, and the monitoring center 7 finally diagnoses the transmission line Whether the structure is abnormal.

The method of using the transmission wire structure to destroy the online monitoring system for monitoring, as shown in Figure 2, is specifically implemented according to the following steps:

Step 1: Build a model to obtain the natural frequency ω ₀ when the wire structure to be tested is normal.

Step 1.1, establish the finite element model of the wire to be diagnosed, which includes hardware such as wire and anti-vibration hammer, wherein the wire is set as a model made of multi-strand steel core and aluminum strands, and cannot be simplified.

Step 1.2, considering the weight of the wire and the anti-vibration hammer, apply wire pretension to the wire in the model, and impose omni-directional constraints on both ends of the wire, conduct modal analysis on the wire in this state, and obtain the wire structure in the normal state The natural frequency ω ₀ under .

Step 2: Collect the actual wind speed and acceleration through the wind speed and direction sensor and the optical fiber acceleration sensor, and calculate the wind speed of the vertical wire.

According to the angle θ between the wind direction and the wire, calculate the wind speed v _x of the vertical wire,

v _x ＝v×sinθ (1)

Where v _x is the wind speed of the vertical wire, and v is the actual wind speed.

Step 3: According to the signal collected by the optical fiber acceleration sensor, after processing with the optical signal modulator and A/D conversion module, the time domain signal is processed by the microprocessor, and the random subspace analysis (SSI) method is used to obtain the wire The natural frequency ω ₁ .

Step 3.1, digitally filter the acceleration signal to filter out high-frequency interference signals above 1kHz;

Step 3.2, constructing the processed wire acceleration signal into a Hankel matrix,

Among them, H _{n1, n2} is the Hankel matrix, which is a matrix composed of the covariance of the conductor vibration acceleration signal, R _i represents the covariance, R _i =E[a _i+1 a _i ], and a _i is the conductor vibration at time i Acceleration, E means expectation, the value range of i is: 1≤i≤(n1+n2-1).

The singular value decomposition of the matrix can be decomposed into the following form,

Among them, U ₁ , V ₁ are unitary matrix, ∑ ₁ is singular value matrix

In addition, according to the state space equation of the randomly excited N-degree-of-freedom system, the covariance of the vibration response of the wire at time i can be written as

R _i =A ^i-1 G(4)

Among them, G=E[v _x a _i ], A is the system matrix

Substituting (4) into (2), we can get

From formula (5), we can get,

Among them, according to formula (3) and formula (5), we can get

Substituting (7) and (8) into (6), the system matrix A can be calculated;

Step 3.3, determine the stable mode of the system matrix A calculated in step 3.2, and obtain the eigenvalue μ _k of the system matrix according to formulas (9) and (10), and then obtain the natural frequency ω _i of the wire through the eigenvalues;

Among them, μ _k is the eigenvalue of the system matrix, Im represents the imaginary part, ξ _i represents the damping ratio of the calculated wire, and ω _i is the natural frequency of the calculated wire, which represents the natural frequency of the wire calculated from the acceleration signal measured at the i-th moment. λ is an intermediate quantity introduced during the derivation of the formula.

Step 3.4: Carry out calculations from steps 3.1 to 3.3 on the acceleration signals collected at different times i, and average the results as the measured natural frequency ω ₁ .

Step 4: Compare the natural frequency ω ₁ measured in step 3 with the natural frequency ω ₀ in the normal state calculated in step 1, when , it is determined that the wire structure is in an abnormal state,

Otherwise, when , it is judged that the wire structure is in a normal state.

Claims (9)

1. a transmission line structure damages on-line monitoring system, is characterized in that, comprises the optical fiber acceleration sensor (1), optical signal demodulator (2), A/D converter (3) and microprocessor (5) that are connected successively ), the microprocessor (5) is also connected with the wind speed and direction sensor (4), and the microprocessor (5) is also connected with the 3G module (6) and the monitoring center (7) in sequence. 2. The on-line monitoring system for structure damage of power transmission wire according to claim 1, characterized in that, said fiber grating acceleration sensor (1) is installed on the power transmission wire, and said optical signal demodulator (2) is installed on On the transmission tower. 3. The on-line monitoring system for the damage of power transmission line structure according to claim 1, characterized in that, the fiber grating acceleration sensor (1) is connected with an optical signal demodulator (2) through an optical fiber, and the optical signal demodulator (2) ) is connected to the A/D conversion module (3) through a shielded twisted pair. 4. The on-line monitoring system for the damage of power transmission lead structure according to claim 1, characterized in that, the A/D conversion module (3) is connected to the microprocessor (5) through a synchronous serial communication interface; wind speed and direction sensor (4) Connect to the microprocessor (5) through RS485. 5. A method for monitoring using a transmission wire structure to damage an online monitoring system, characterized in that, it is specifically implemented according to the following steps: Step 1, establish a model, and obtain the natural frequency ω ₀ when the wire structure to be detected is normal; Step 2, collect the actual wind speed and acceleration through the wind speed and direction sensor and the optical fiber acceleration sensor, and calculate the wind speed of the vertical wire; Step 3, according to the signal collected by the optical fiber acceleration sensor, after processing by the optical signal modulator and A/D conversion module, the time domain signal is processed by the microprocessor, and the natural frequency ω of the wire is obtained by the random subspace analysis method ₁ ; Step 4, compare the natural frequency ω ₁ measured in step 3 with the natural frequency ω ₀ in the normal state calculated in step 1, and judge the state of the wire structure. 6. The method for monitoring by an online monitoring system for damage to the structure of a transmission wire according to claim 5, wherein said step 1 is specifically: Step 1.1, establishing a finite element model of the wire to be diagnosed, which includes hardware such as wire and anti-vibration hammer, wherein the wire is set as a model made of multi-strand steel core and aluminum strands, and cannot be simplified; Step 1.2, considering the weight of the wire and the anti-vibration hammer, apply wire pretension to the wire in the model, and impose omni-directional constraints on both ends of the wire, conduct modal analysis on the wire in this state, and obtain the wire structure in the normal state The natural frequency ω ₀ under . 7. The method according to claim 5, wherein the online monitoring system for damage to the structure of the transmission conductor is used for monitoring, wherein the step 2 is specifically to calculate the wind speed v _x of the vertical conductor according to the angle θ between the wind direction and the conductor , v _x ＝v×sinθ (1) Where v _x is the wind speed of the vertical wire, and v is the actual wind speed. 8. The method for monitoring by an online monitoring system for structure damage of power transmission conductors according to claim 5, characterized in that, said step 3 is specifically, Step 3.1, digitally filter the acceleration signal to filter out high-frequency interference signals above 1kHz; Step 3.2, constructing the processed wire acceleration signal into a Hankel matrix, Among them, H _{n1, n2} is the Hankel matrix, which is a matrix composed of the covariance of the conductor vibration acceleration signal, R _i represents the covariance, R _i =E[a _i+1 a _i ], and a _i is the conductor vibration at time i Acceleration, E means expectation, the value range of i is: 1≤i≤(n1+n2-1); The singular value decomposition of the matrix can be decomposed into the following form, <mrow><msub><mi>H</mi><mrow><mi>n</mi><mn>1</mn><mo>,</mo><mi>n</mi><mn>2</mn></mrow></msub><mo>=</mo><mfenced open = "[" close = "]"><mtable><mtr><mtd><msub><mi>U</mi><mn>1</mn></msub></mtd><mtd><msub><mi>U</mi><mn>2</mn></msub></mtd></mtr></mtable></mfenced><mfenced open = "[" close = "]"><mtable><mtr><mtd><msub><mi>&amp;Sigma;</mi><mn>1</mn></msub></mtd><mtd><mn>0</mn></mtd></mtr><mtr><mtd><mn>0</mn></mtd><mtd><mn>0</mn></mtd></mtr></mtable></mfenced><mfenced open = "[" close = "]"><mtable><mtr><mtd><msubsup><mi>V</mi><mn>1</mn><mi>T</mi></msubsup></mtd></mtr><mtr><mtd><msubsup><mi>V</mi><mn>2</mn><mi>T</mi></msubsup></mtd></mtr></mtable></mfenced><mo>=</mo><msub><mi>U</mi><mn>1</mn></msub><msub><mi>&amp;Sigma;</mi><mn>1</mn></msub><msubsup><mi>V</mi><mn>1</mn><mi>T</mi></msubsup><mo>=</mo><msub><mi>U</mi><mn>1</mn></msub><msubsup><mi>&amp;Sigma;</mi><mn>1</mn><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msubsup><mi>I</mi><mo>&amp;CenterDot;</mo><msup><mi>I</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup><msubsup><mi>&amp;Sigma;</mi><mn>1</mn><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msubsup><msubsup><mi>V</mi><mn>1</mn><mi>T</mi></msubsup><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mrow> Among them, U ₁ , V ₁ are unitary matrix, ∑ ₁ is singular value matrix In addition, according to the state space equation of the randomly excited N-degree-of-freedom system, the covariance of the vibration response of the wire at time i can be written as R _i =A ^i-1 G (4) Among them, G=E[v _x a _i ], A is the system matrix Substituting (4) into (2), we can get <mrow><msub><mi>H</mi><mrow><mi>n</mi><mn>1</mn><mo>,</mo><mi>n</mi><mn>2</mn></mrow></msub><mo>=</mo><mfenced open = "[" close = "]"><mtable><mtr><mtd><mi>I</mi></mtd></mtr><mtr><mtd><mi>A</mi></mtd></mtr><mtr><mtd><mtable><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr></mtable></mtd></mtr><mtr><mtd><msup><mi>A</mi><mrow><mi>i</mi><mo>-</mo><mn>1</mn></mrow></msup></mtd></mtr></mtable></mfenced><mo>&amp;lsqb;</mo><msup><mi>A</mi><mrow><mi>i</mi><mo>-</mo><mn>1</mn></mrow></msup><mi>G</mi><mo>,</mo><msup><mi>A</mi><mrow><mi>i</mi><mo>-</mo><mn>2</mn></mrow></msup><mi>G</mi><mo>,</mo><mo>...</mo><mo>,</mo><mi>G</mi><mo>&amp;rsqb;</mo><mo>=</mo><msub><mi>P</mi><mi>i</mi></msub><msub><mi>Q</mi><mi>i</mi></msub><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>5</mn><mo>)</mo></mrow></mrow> From formula (5), we can get, <mrow><mi>A</mi><mo>=</mo><msubsup><mi>P</mi><mi>i</mi><mo>&amp;UpArrow;</mo></msubsup><msubsup><mi>Q</mi><mi>i</mi><mo>&amp;UpArrow;</mo></msubsup><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>6</mn><mo>)</mo></mrow></mrow> Among them, according to formula (3) and formula (5), we can get <mrow><msub><mi>P</mi><mi>i</mi></msub><mo>=</mo><msub><mi>U</mi><mn>1</mn></msub><msubsup><mi>&amp;Sigma;</mi><mn>1</mn><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msubsup><mi>I</mi><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>7</mn><mo>)</mo></mrow></mrow> <mrow><msub><mi>Q</mi><mi>i</mi></msub><mo>=</mo><msup><mi>I</mi><mrow><mo>-</mo><mn>1</mn></mrow></msup><msubsup><mi>&amp;Sigma;</mi><mn>1</mn><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msubsup><msubsup><mi>V</mi><mn>1</mn><mi>T</mi></msubsup><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>8</mn><mo>)</mo></mrow></mrow> Substituting (7) and (8) into (6), the system matrix A can be calculated; Step 3.3, determine the stable mode of the system matrix A calculated in step 3.2, and obtain the eigenvalue μ _k of the system matrix according to formulas (9) and (10), and then obtain the natural frequency ω _i of the wire through the eigenvalues; <mrow><mi>&amp;lambda;</mi><mo>=</mo><mfrac><mn>1</mn><mrow><mi>&amp;Delta;</mi><mi>t</mi></mrow></mfrac><msub><mi>ln&amp;mu;</mi><mi>k</mi></msub><mo>=</mo><mo>-</mo><msub><mi>&amp;xi;</mi><mi>i</mi></msub><msub><mi>&amp;omega;</mi><mi>i</mi></msub><mo>-</mo><msub><mi>j&amp;omega;</mi><mi>i</mi></msub><msqrt><mrow><mn>1</mn><mo>-</mo><msubsup><mi>&amp;xi;</mi><mi>i</mi><mn>2</mn></msubsup></mrow></msqrt><mo>;</mo><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>9</mn><mo>)</mo></mrow></mrow> <mrow><msub><mi>&amp;omega;</mi><mi>i</mi></msub><mo>=</mo><mo>-</mo><mi>Im</mi><mrow><mo>(</mo><mi>&amp;lambda;</mi><mo>)</mo></mrow><mo>/</mo><msqrt><mrow><mn>1</mn><mo>-</mo><msubsup><mi>&amp;xi;</mi><mi>i</mi><mn>2</mn></msubsup></mrow></msqrt><mo>-</mo><mo>-</mo><mo>-</mo><mrow><mo>(</mo><mn>10</mo>mn><mo>)</mo></mrow></mrow> Among them, μ _k is the eigenvalue of the system matrix, Im represents the imaginary part, ξ _i represents the damping ratio of the calculated wire, ω _i is the natural frequency of the calculated wire, and represents the natural frequency of the wire calculated from the acceleration signal measured at the i-th moment; λ It is an intermediate quantity introduced during formula derivation; Step 3.4: Carry out calculations from steps 3.1 to 3.3 on the acceleration signals collected at different times i, and average the results as the measured natural frequency ω ₁ . 9. The method according to claim 5 that utilizes the transmission line structure to damage the on-line monitoring system for monitoring, wherein said step 4 is specifically, the natural frequency ω ₁ measured in step 3 and calculated in step 1 Comparing with the obtained natural frequency ω ₀ in the normal state, when , it is determined that the wire structure is in an abnormal state, Otherwise, when , it is judged that the wire structure is in a normal state.