KR20020088523A - Detection of Arcing Faults in Transmission Lines and Method for Fault Distance Estimation - Google Patents

Abstract

PURPOSE: A method for detecting an arc accident and estimating a failure distance in a power transmission line is provided to detect rapidly a failure of the power transmission line by separating a temporary failure and a permanent failure of power transmission line. CONSTITUTION: A failure voltage and current are generated by an EMTP(Electro Magnetic Transients Program)(S100). The magnitude of arc voltage is obtained by an LSE(Least Square Error) method through Matlab(S110). A temporary failure or a permanent failure is determined by the kind of accident generated from a power transmission line(S120). A reclosing process is performed if the magnitude of the arc voltage is determined as the temporary failure(S130,S140). A filtering process is performed by using a butterworth low pass filter if the magnitude of the arc voltage is determined by the permanent accident(S150,S160). A DC component is removed by using a DC-offset removal filter(S170). A failure distance is estimated by extracting the voltage without the DC component and a reference wave of current data and impedance and calculating their impedance.

Description

Detection of Arcing Faults in Transmission Lines and Method for Fault Distance Estimation

The present invention relates to an arc accident detection and fault distance estimation method of a transmission line, and more particularly, to distinguish between temporary failure and permanent failure in a transmission line to perform reclosing in the event of a temporary failure, in particular, when a permanent failure occurs. ㆍ Arc of transmission line which removes harmonics and direct current component of current signal and extracts fundamental wave component, and can detect fault and distance of transmission line faster and more accurately in case of permanent failure of transmission line. The present invention relates to an accident detection method and a failure distance estimation method.

In general, as the industry develops and the standard of living improves, the demand for electric power gradually increases, and the facilities constituting the electric power system are increasing in capacity and diversification.

Accordingly, in order to supply high-quality electric power, that is, reliable electric power, in addition to the modernization of electric power facilities, rational operation of the electric power system and prompt recovery of failures are required.

In the event of a failure in the power system, the system quickly finds the point of occurrence of the fault, isolates the fault occurrence section from the sound section, reduces the adverse effect of the sound section, and restores the fault section quickly. The protection relay method for the operation of the system has been studied for a long time.

In general, the protection relay in the power system is used to maintain the system stability and suppress the damage to the equipment through the rapid and accurate removal of the accident.

Most of these accidents in the power system are caused by transmission lines, and temporary failures caused by flashovers account for 80 to 90% of all accidents.

On the other hand, in addition to the accident detection relay, the transmission line protection relay system adds an auto-reclosing relay, waits for dead time for a certain period of time after the accident is interrupted, and re-inserts the circuit breaker to automatically repair the transmission network within a relatively short time. Control to achieve.

As a result, it is effective to maintain system stability, supply reliability, and improve facility utilization rate, and the automatic reclosing method has been used for a long time.

The reason for the use of the automatic reclose relay in the transmission line protection method starts from the fact that most accidents occurring in the transmission line are caused by instantaneous flashover.

In this case, if the line is cut off and the voltage is left unattended for a certain period of time, the arc at the accident site is extinguished and the ionized air achieves insulation recovery. At this time, if the line is connected again, power transmission can be continued normally.

The application of this method is common in most utilities and maintains the reliability of supply by automatic recovery operation in case of temporary failure, maintains or improves the transient stability of the system, and improves the facility utilization rate and reduces the power loss by reducing the line downtime. There is.

Although the high-speed automatic reclosing method has a great effect on maintaining system stability and supply reliability upon success, it has been found to have an adverse effect upon failure. Particularly, a high-speed turbine-generator generates shaft-torsional shock, which greatly shortens the life span. It is a factor.

That is, there is a problem that electrical and mechanical shocks occur in power devices such as generators and transformers.

As described above, the prior art has a high failure rate of automatic reclosing by fixing the no-voltage time of the automatic reclosing relay and evaluating the margin of system stability. Also, when the accident is already reconstituted or the insulation recovery of the fixed part is insufficient, When re-accident occurred due to the closing, there were problems that electric and mechanical shocks could occur in the power equipment.

The present invention has been made to solve the above problems, the object of the present invention is to distinguish between temporary failure and permanent failure in the transmission line to perform re-closing in the event of temporary failure, in particular in the case of permanent failure input voltage and current By eliminating harmonics and direct current components and extracting the fundamental wave components, the detection and failure of arc accidents on transmission lines that can detect faults and estimate the distance of transmission lines more quickly and accurately in case of permanent failure of transmission lines To provide a distance estimation method.

1 is a diagram showing a schematic diagram used to determine whether a temporary failure or permanent failure in an accident according to an embodiment of the present invention;

2a or 2b is a view showing the voltage waveform in the temporary failure and permanent failure according to an embodiment of the present invention

3 is a flowchart illustrating a method for detecting an arc accident and measuring a fault distance of a transmission line according to an embodiment of the present invention.

4 is a view for explaining a failure distance estimation according to an embodiment of the present invention

5 and 6 are diagrams showing the results of simulation by only changing the type of failure under the same conditions, such as failure angle and failure distance is 0 ° and 30% (7.8 km) according to an embodiment of the present invention

7 and 8 are views showing the result when the failure distance is changed to 90% when the failure angle is the same according to an embodiment of the present invention

9A and 9B are diagrams showing voltage waveforms passing through a low pass filter when the failure angle is 0 ° and 90 ° for permanent failure according to an embodiment of the present invention.

10A and 10B are diagrams illustrating current waveforms passing through a DC-offset elimination filter when failure distances are the same and failure angles are 0 ° and 60 °, respectively, according to an exemplary embodiment of the present invention.

11A and 11B are diagrams illustrating a convergence process of resistance components according to a failure distance at failure angles 0 ° and 90 ° according to an embodiment of the present invention.

12A and 12B are views illustrating a convergence process of reactance components according to a failure distance at failure angles 0 ° and 90 ° according to an embodiment of the present invention.

13A and 13B illustrate the convergence characteristics of the resistance and reactance of a half-cycle discrete Fourier transform (HCDFT) and one-cycle discrete Fourier transform (FCDFT) according to an embodiment of the present invention at a failure angle of 60 ° and a failure distance of 40%. Compared drawing

14A and 14B illustrate a process of convergence of resistance and reactance by varying only a failure distance when a failure angle is 0 ° according to an embodiment of the present invention.

15A and 15B illustrate a process of convergence of resistance and reactance by varying only a failure distance when a failure angle is 90 ° according to an embodiment of the present invention.

In order to achieve the above object, the arc accident detection and fault distance measuring method of the transmission line of the present invention includes a first step of generating an accident having a signal characteristic of temporary failure or permanent failure; A second step of detecting an arc voltage from a failure signal generated by the accident, calculating a magnitude of the arc voltage, and determining a temporary failure and a permanent failure; A third step of immediately re-closing when the detected data is temporarily broken; A fourth step of filtering using a low pass filter for removing harmonic components when the detected data is permanently broken; A fifth step of filtering using a dishoff offset removing filter to remove a DC component of the filtered data; Extracting a fundamental wave of the data from which the DC component is removed and calculating an impedance thereof; And a seventh step of estimating a fault distance by using the calculated data.

In this case, it is preferable that the low pass filter uses a secondary Butterworth low pass filter.

In addition, it is preferable to use any one method selected from one cycle Discrete Fourier Transform (FCDFT), half cycle Discrete Fourier Transform (HCDFT) and Walsh (Walsh) function.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. This embodiment is not intended to limit the scope of the invention, but is presented by way of example only.

1 is a diagram illustrating a system diagram used to determine whether a temporary failure or a permanent failure occurs in an accident as an embodiment of the present invention. Referring to FIG. 1, an arc model including a zinc oxide (ZnO) lightning arrester, a resistor (R), and a reactance (L) was used to determine temporary failure and permanent failure in an accident.

On the other hand, the failure of the transmission line can be divided into temporary failure and permanent failure. Permanent failures include ground faults that occur when the wires fall to the ground and short circuits that occur due to short circuits between the wires. On the other hand, temporary failure is an accident in which the transmission line is temporarily broken down by parameters such as lightning, climate change, and wind caused by the natural environment, and the fault current accompanying the arc flows along the ground line. . At this time, the generated arc becomes an important factor in reclosing, which will be described with reference to FIG. 2A or 2B.

2A or 2B are diagrams showing voltage waveforms at transient and permanent failures. Referring to FIG. 2A, the point A is a voltage waveform of a temporary failure, and the point A is a moment when an accident occurs on the line, and the point B is a time when an accident is detected and the breaker operates. At this time, a secondary arc occurs due to the switching action, and the arcing and re-firing are repeated by the high frequency component. And at point C, SO is given.

Meanwhile, referring to FIG. 2B, an accident occurs at a point A as a voltage waveform of permanent failure and a breaker operates at a point B. FIG. However, even after the breaker is activated, a constant voltage is induced, rather than a repetition of SO and ATI.

3 is a flowchart illustrating a method for detecting an arc accident and measuring a distance of a transmission line according to an embodiment of the present invention. First, a failure generated by an EMTP (Electro Magnetic Transients Program), a power system transient analysis program, as a preprocessing process. With respect to voltage and current (S100), the magnitude of the arc voltage is determined by a least square error method (LSE) through a matlab to determine what kind of an accident occurs on a transmission line (S110, S120).

In this case, the preprocessing process analyzes the input signals (voltage and current) as symmetrical components (that is, normal, image, and reverse phase components of the transmission line). Therefore, each symmetrical component is represented by (1).

Where V _p , V _n and V ₀ are the voltages of the normal, reverse and image components, respectively, and I _p , I _n and I ₀ are the currents of the normal, reverse and image components, respectively. Resistance and reactance in normal and reverse phase lines, R ₀ and L ₀ are resistance and reactance in video segment. V _ap , V _an , and V _a0 are arc voltages of the normal, reverse phase, and image fractions, respectively.

Then, using the principle of superimposition on the equations defined in Equation 1, the following Equation 2 comes out.

here, Where Va is the magnitude of the arc voltage, and ε is the error of all measurement errors, modeling of the line, and arcs.

Next, when (Equation 2) is applied to the least square error method (LSE) used as a system solution in the case where the number of equations is larger than the unknown number, it is applied to the matrix of Equation 3 below. The size is determined.

Where R is the resistance of the line, L_e is the equivalent impedance of the line, and V_a is the magnitude of the arc voltage. And, ,

,

,

,

,

to be.

On the other hand, if the magnitude of the arc voltage is determined as a temporary failure (S130), the re-closing is performed immediately (S140), otherwise, if the magnitude of the arc voltage is determined as a permanent failure (S150), harmonic components generated during switching In order to remove the filter, a low pass filter is used to filter (S160). In this case, the low pass filter (LPF) used a second, that is, a second Butterworth low pass filter which is determined to be the best in terms of filtering capability and speed in the first to tenth order.

At this time, the transfer function of the second Butterworth low pass filter is as follows.

On the other hand, the harmonic component of the voltage signal in a system accident can be effectively removed using a second Butterworth lowpass filter, but the DC-offset component included in the current signal is not removed. It will be included. In the method of using the fundamental wave components of voltage and current, the accurate fundamental wave component cannot be obtained without removing the direct current component, which causes an unavoidable error.

Therefore, in the present invention, to remove the DC component of the voltage or current data passing through the low pass filter is filtered with a DC-offset removing filter (S170). In this case, the DC-offset elimination filter is implemented as shown in Equation 5 below.

here, Is the sampling interval, τ is the time constant, and N is the number of samples per period.

Next, the fundamental distance of the voltage or current data from which the DC component is removed is extracted, and the impedance is calculated to estimate the failure distance (S180 and S190).

On the other hand, many algorithms used in rangefinders extract the fundamental components of the voltage and current obtained from the samples, and find their impedance to the point of failure through their proper ratio. Thus, the nature of these algorithms depends on how accurately the fundamental components of voltage and current can be obtained from small samples. Therefore, in the present invention, a method for extracting fundamental waves uses a method using orthogonal transformation of Discrete Fourier Transform (DFT) and Walsh function.

In this case, the Discrete Fourier Transform (DFT) is as shown in Equation 6 below.

here, to be.

In Equation 6, k denotes an order of harmonics, and when k is 1, a component of a fundamental frequency can be obtained. Therefore, Equation 6 is a formula for a one-cycle discrete Fourier transform (FCDFT) using all of one period of sample data, and the half-cycle data in order to obtain a fundamental wave component more quickly. The equation representing the half cycle Discrete Fourier transform (HCDFT) using only HCDF ?? is given by the following equation (7).

As a result, voltage and current signals with high-order harmonics and DC-offsets are passed through discrete Fourier transform (DFT), that is, FCDFT and HCDFT filters. Using the ratio of, it is easy to find the impedance to the point of failure.

In addition, one of the methods used as a method for extracting the fundamental wave is a method using a Walsh function, and the Walsh function is defined in the interval [0, 1). Here, 1 means a normalized value. Any function f (t) that can be integrated can be developed in a finite series such as the following Walsh function in the interval [0,1).

Here, the Walsh coefficient F _i can be obtained as a requirement of minimizing the following mean square error using the orthogonality of the following expression (9).

Here, Pal (i, t) is the Walsh function of the binary array, and F _i is the coefficient of the Walsh function Pal (i, t) of the I'th.

On the other hand, in order to minimize the error equation defined as in Equation (9), the partial differential value for F _i should be zero.

Further, due to the orthogonal characteristics, the coefficient F _i is represented by the following expression (10).

Here, the error in Equation 10 becomes smaller as the expansion term of the Walsh function increases.

On the other hand, if a short circuit accident occurs in the line, there is no video current, but in the event of a ground fault, an unbalance occurs and the video current and the video voltage exist. Therefore, the impedance measured at the ground fault includes the image impedance in addition to the normal impedance. Therefore, even if the accident occurs at the same point, the impedance value of the line in the case of short-circuit and ground fault is different from the electric distance. Short circuit protection distance relays measure the normal impedance of the transmission line. However, in the event of a ground fault, the relay may be inoperable due to the occurrence of underreach of the relay due to the presence of the image current. Therefore, the correct operation of the relay can be obtained only by compensating for the error caused by the image current. .

Figure 4 is a diagram for estimating a fault distance according to one embodiment of the present invention, when a ground fault occurs on the A of the transmission line, the incident of the relay installation point voltage V _A is the following (Equation 11) and of It is expressed as

V _A = V ₀ + V ₁ + V ₂ ---------------------------------- (Equation 11)

Here, V ₀ , V ₁ , V ₂ are symmetrical voltages at the relay installation point.

Further, since V ₀ = I ₀ Z ₀ , V ₁ = I ₁ Z ₁ , V ₂ = I ₂ Z ₂ per unit distance [km], the following Equation 12 is obtained.

Therefore, the transmission line impedance from the relay installation point to the accident point is expressed by the following equation (13).

Where V ₀ , V ₁ , V ₂ are the symmetrical voltages at the relay installation point,

I ₀ + I ₁ + I ₂ is the symmetrical current on the fault line of the relay installation point,

I ₀ 'is the video current at the sound circuit of the relay installation point,

Z ₀ + Z ₁ + Z ₂ is the symmetric impedance of the transmission line per unit distance (Z ₁ = Z ₂ ),

Z _L is the line impedance (Z _L = Z ₁ × L) from the relay installation point to the accident point,

Zm is the mutual impedance between the lines.

As shown in Equation 12, in order to obtain the impedance of the ground fault in the ground fault, Section The term should be added. Equation (12) above relates to a two-wire transmission line, but in the case of one line Just delete the term and apply it. That is, Z ₀ , Z ₁ , Z ₂ , Zm are known values, Since the value can be easily obtained, the impedance up to the point of failure can be obtained by simple calculation.

The summary of the research process of the present invention is as follows.

In the present invention, in order to efficiently perform the algorithm for the arc accident detection and fault distance estimation is shown to be simulated using a GUI (Graphic User Interface).

In the present invention, by determining whether an accident occurring in a transmission line is a temporary failure or a permanent failure, in the case of a permanent failure, a protection algorithm is performed through a distance relay. Therefore, in order to distinguish between temporary failure and permanent failure, a waveform similar to the arc voltage is generated using a zinc oxide (ZnO) lightning arrester model and used as an input, and based on this, an arc accident is detected. The model system is 26 [km] with two power sources of 240 [MVA] and 180 [MVA] at both ends of the track. This model is a real system model between Yongin and Anseong, and the model system was simulated by EMTP to obtain data.

Table 1 shows the fault types and fault conditions simulated for the validity of the algorithm. Types of failure were ground fault and 1-line arc accident, and the fault distance occurred at 10% intervals, that is, 2.6km intervals, with a total distance of 26 [km] as 100 (%). Failure angles are 0 °, 30 °, 60 ° and 90 °. In this fault type and fault condition, both 1-line ground fault and 1-line arc accident are used to detect the arc accident, but the fault distance estimation algorithm assumes that a permanent fault such as a 1-line ground fault occurred on the transmission line. Only first-line ground faults are simulated.

In addition, two algorithms for detecting arc accidents were performed by varying the fault occurrence distance and the angle of failure. The input data was simulated by taking 10 cycles of 48 samples per cycle.

[Table 1] Simulated Failure Types and Failure Conditions

Fault type First-line ground fault Fault occurrence distance 10% (2.6km) Fault angle 0 ° 20% (5.2km) 30% (7.8km) 30 ° 40% (10.4km) 50% (13.0km) 60 ° 60% (15.6km) 70% (18.2km) 90 ° 80% (20.8km) 90% (23.4km) 1-line arc accident Fault occurrence distance 10% (2.6km) Fault angle 0 ° 20% (5.2km) 30% (7.8km) 30 ° 40% (10.4km) 50% (13.0km) 60 ° 60% (15.6km) 70% (18.2km) 80% (20.8km) 90 ° 90% (23.4km)

5 and 6 are diagrams showing simulation results of different types of failures under the same conditions at which the occurrence angle and the failure distance are 0 ° and 30% (7.8 km). The upper waveform is obtained by the least square error method. The convergence process of all samples is shown. The waveform below shows the resulting convergence of the graph as the last 10 samples. Referring to FIG. 5, it can be seen that the magnitude of the arc voltage converges to a value of about 4 × 10 ⁴ [V]. Referring to high 6, the magnitude of the arc voltage is about 50 [V] or less. You can see the convergence. Therefore, it can be seen that the magnitude of the arc voltage has a very large difference in the case of temporary failure simulated by the one-line arc accident and the permanent accident simulated by the one-line ground fault.

7 and 8 show results when the failure distance is changed to 90% when the failure angles are the same. As shown in FIGS. 5 and 6, the arc voltages of the temporary failure and the permanent failure are shown in FIG. The convergence values are distinctly different.

This shows that the detection of arc voltage is independent of the failure distance and the angle of occurrence.

As described above, in the case of temporary failure, the magnitude of the arc voltage was not significantly affected by the failure angle or the failure distance, and the convergence of the arc voltage was about 4 × 10 ⁴ [V]. In addition, in case of permanent failure simulated by 1-line ground fault, it is not influenced by the angle of failure or the distance of failure as in case of temporary failure. However, the magnitude of the arc voltage converged through the algorithm is less than 50 [V]. As a result, in the case of temporary failure and permanent failure, the magnitude of the arc voltage converged by the algorithm shows a very large voltage difference.

Therefore, the input data used for the detection of the arc voltage was simulated using one cycle of 48 samples and 10 cycles. The arc voltage convergence values obtained as a result of the simulation using the least-squares error method converge within 2 cycles after the failure, so the arc voltage convergence value can be known before 2 cycles after the accident. Automatic reclosing and distance relaying can be performed.

9A and 9B are diagrams showing voltage waveforms passing through a low pass filter when failure angles are 0 ° and 90 ° for permanent failure, and are mainly included in voltage components as a preprocessing process for extracting fundamental waves. The simulation results of the second-order Butterworth lowpass filter to remove harmonics are as follows. In general, harmonics are greatly affected by the angle of failure, and the effects of harmonics increase from 0 ° to 90 °. Therefore, the fault voltage waveform when the fault distance is the same and the fault angle is 0 ° and 90 ° and the voltage waveform after the harmonics are removed. If a fault occurs, the voltage of the fault phase becomes smaller than the other phases. The voltage passing through the low-pass filter decreases in magnitude than the original voltage, and phase delay occurs.

After that, when a failure occurs in the transmission line, the voltage includes a large amount of harmonic components, whereas the current includes a large number of DC components that generally decrease exponentially. Unlike the harmonics of the voltage, the distortion of the current waveform due to the direct current component is most severe at the failure angle of 0 ° and shows good results toward 90 °. In case of distance relay by extracting fundamental wave, it is necessary to remove these DC components properly to obtain accurate results. Therefore, it is necessary to filter to remove the DC offset. 10A and 10B are diagrams showing current waveforms passing through a DC-offset elimination filter when the failure distances are the same and the failure angles are 0 ° and 60 °, respectively. It is the largest at 0 ° and becomes smaller as the failure angle increases.

As described above, the fundamental wave extraction and the impedance were calculated using voltage and current data obtained through the second-order Butterworth low pass filter and the DC-offset elimination filter. HCDFT, FCDFT and Walsh functions were used to extract the fundamental wave.

11A and 11B are diagrams illustrating the convergence process of resistance components according to fault distances at fault angles of 0 ° and 90 °, and are shown after a half cycle after an accident and 4 cycles after a failure. .

12A and 12B illustrate a process of convergence of reactance components according to failure distances at failure angles 0 ° and 90 °. In comparison with FIGS. 11A and 11B, the resistance component is faster at 90 ° than at 0 °. You can see the convergence. This is due to the DC component included in the current after the accident. Even if the fault voltage and current go through a DC-offset rejection filter, the DC component may not be completely removed and the phase change and magnitude after passing through the filter. In the case of 0 ° failure due to the error of the compensation process for change, the DC component remains relatively faster than the case of 90 °, so it shows relatively fast convergence at 90 °. On the other hand, as shown in Figure 12a and 12b, the convergence rate of the reactance component is shown that the case of 0 ° is faster than the case of 90 °.

Since the HCDFT uses only half-cycle of FCDFT, the convergence speed is relatively high. However, since only half-cycle of FCDFT using all of one period of data is used, the HCDFT oscillates slightly larger at the convergence point. This is a result of the small amount of data used. 13A and 13B are diagrams comparing the convergence characteristics of resistance and reactance of HCDFT and FCDFT at a failure angle of 60 ° and a failure distance of 40%.

[Table 2] compares the resistance and reactance values of the real system with the resistance and reactance components extracted by HCDFT and FCDFT when the failure angle and the failure distance are different. Although the R and L values obtained through HCDFT show slight differences, this is due to the sampling frequency and the error during the preprocessing to extract the fundamental wave. In addition, the maximum error compared to the actual value shows the resistance of about 0.0356 [Ohm] and the reactance value of about 0.12 [Ohm]. This is a very small value in the length of the entire transmission line, which is an acceptable error.

[Table 2] Comparison of actual values and R, L values through HCDFT, FCDET

10% (2.6 km) 30% (7.8 km) 50% (13km) 70% (18.2km) Actual value R L R L R L R L 0.1089 0.8622 0.3268 2.5865 0.5447 4.3108 0.7626 6.0351 0 ° HCDFT 0.1075 0.8530 0.328 2.5655 0.555 4.3056 0.7982 6.111 FCDFT 0.1705 0.8532 0.3273 2.568 0.5562 4.307 0.796 6.115 30 ° HCDFT 0.1075 0.8532 0.3268 2.5686 0.552 4.306 0.778 6.115 FCDFT 0.1073 0.8532 0.3288 2.5678 0.5560 4.3074 0.794 6.1154 90 ° HCDFT 0.119 0.8584 0.3278 2.5701 0.5553 4.3295 0.7982 6.1529 FCDFT 0.1075 0.8583 0.3278 2.5701 0.555 4.3295 0.796 6.1529

Next, the basic wave is extracted using the Walsh function. 14A and 14B are diagrams illustrating a convergence process of resistance and reactance by varying only a failure distance when the failure angle is 0 ° or when the failure angle is 90 °. Using the) function to extract the fundamental wave has similar results as using the FCDFT. However, when using the Walsh function, the computation time is slightly longer than the FCDFT.

[Table 3] compares the actual values with the resistance and reactance values extracted using the FCDFT and Walsh functions. These values were calculated with four cycles of data after a failure, and compared with Table 2 above. Failure angles are three cases: 0 °, 30 °, and 90 °. The fault distances are 10%, 30%, 50%, and 70%.

[Table 3] Comparison of actual values and R, L values through FCDET and Walsh functions

10% (2.6 km) 30% (7.8 km) 50% (13km) 70% (18.2km) Actual value R L R L R L R L 0.1089 0.8622 0.3268 2.5865 0.5447 4.3108 0.7626 6.0351 0 ° WALSH 0.1070 0.8540 0.3268 2.5714 0.5542 4.3209 0.7936 6.1401 FCDFT 0.1075 0.8532 0.3273 2.568 0.5562 4.307 0.796 6.115 30 ° WALSH 0.1069 0.8541 0.3273 2.5714 0.5541 4.3209 0.6718 6.1402 FCDFT 0.1073 0.8532 0.3288 2.5678 0.5560 4.3074 0.794 6.1154 90 ° WALSH 0.1084 0.8565 0.3233 2.5598 0.5522 4.3101 0.7929 6.129 FCDFT 0.1075 0.8583 0.3278 2.5701 0.555 4.3295 0.796 6.1529

Compared with the above results, in the case of using Walsh function, the resistance and reactance values according to the failure conditions such as the failure distance and the angle of occurrence of the failure have almost no error compared with the actual values and the FCDFT. Able to know.

Therefore, as described above, the present invention is an arc accident detection and failure distance estimation method of a transmission line, and distinguishes temporary failure and permanent failure in a transmission line to perform reclosing when a temporary failure occurs, in particular, when a permanent failure occurs. By filtering the harmonics and direct current components of voltage and current signals and extracting the fundamental wave components, there is an advantage that the fault detection and fault distance of the transmission line can be estimated more quickly and accurately in case of permanent failure of the transmission line.

The present invention is not limited to the above-described embodiments, and it will be apparent that many modifications are possible by those skilled in the art within the technical spirit of the present invention.

Claims (6)

A first step of generating an accident having a signal characteristic of temporary failure or permanent failure; A second step of detecting an arc voltage from a failure signal generated by the accident, calculating a magnitude of the arc voltage, and determining a temporary failure and a permanent failure; A third step of immediately re-closing when the detected data is temporarily broken; A fourth step of filtering using a low pass filter for removing harmonic components when the detected data is permanently broken; A fifth step of filtering using a deoffset elimination filter to remove the direct current component of the filtered data; Extracting a fundamental wave of the data from which the DC component is removed and calculating an impedance thereof; And a seventh step of estimating a fault distance by using the calculated data. According to claim 1, In the step of causing the accident, Arc accident detection and fault distance estimation method of a transmission line, characterized in that executed by different accident distance and accident angle. According to claim 1, In the step of determining the temporary voltage and permanent failure by calculating the arc voltage detection and magnitude, Pre-processing the fault signal into a symmetrical component of voltage and current, and calculating the magnitude of line resistance, inductance and arc voltage using a least square error method. The method of claim 1, wherein the low pass filter, An arc accident detection and fault distance estimation method of a transmission line, comprising a second Butterworth low pass filter. The method of claim 1, wherein the DC offset elimination filtering is performed by the following Equation (5). here, Is the sampling interval, τ is the time constant, and N is the number of samples per period. The transmission line of claim 1, wherein the fundamental wave extraction method uses any one method selected from one cycle Discrete Fourier Transform (FCDFT), Half Cycle Discrete Fourier Transform (HCDFT) and Walsh (Walsh) functions. Arc accident detection and fault distance estimation method.