CN102253315A - Fault location method based on single-terminal location - Google Patents

Abstract

The present invention is a fault location method based on single-end distance measurement. When a short circuit occurs in the transmission line, the transmission line traveling wave fault distance measurement device is used to measure the power frequency electrical quantity of the bus bar at the local end of the transmission line, and the range of the fault point is determined by the impedance method. Transition resistance value; then analyze the transient voltage/current traveling wave through wavelet transform, and judge the fault as a common short circuit fault, then use the single-ended traveling wave method combined with the line length to directly calculate the fault point position; if it is a special short circuit fault, use the impedance method The single-ended fault location method of transmission line combined with the traveling wave method to calculate the fault point location. The invention utilizes the single-end traveling wave method to ensure the accuracy of fault distance measurement, and the distance measurement accuracy of the single-end traveling wave method can reach within 500m, and the distance measurement accuracy is not affected by factors such as line length. The invention can also adapt to distance measurement under different fault types, and is basically not affected by factors such as transition resistance, line structure, system operation mode and the like.

Description

Fault location method based on single-ended ranging

Technical field:

The invention relates to the field of power system automation, in particular to a fault location method based on single-end ranging.

Background technique:

After the transmission line fails, even if the reclosure is successful, line inspectors are required to find the fault point, and judge whether the line can continue to operate or whether it needs to be powered off for maintenance according to the degree of damage caused by the fault, so as to eliminate hidden dangers. Therefore, quickly finding the fault point after the line fault becomes a key technology to ensure the safe and stable operation of the power grid. Among them, in 110kV and above power grids, transmission line fault location devices are widely used in power stations where the neutral point is directly grounded, which fully demonstrates its importance to the safe, stable and reliable operation of the power system.

With the development of smart grid construction, the intelligentization of substations has become a development trend. In intelligent substations, electronic transformers are used to replace conventional ferromagnetic transformers, and data sharing requirements are put forward for various devices. Therefore, the data format and communication protocol of the traveling wave fault location device also need to be modified accordingly, which leads to interconnection and intercommunication problems with the existing distance measurement device. In this case, it is difficult to implement fault distance measurement in a double-ended manner.

The existing traveling wave fault location devices basically work in a double-terminal mode, and their reliability and accuracy basically meet the needs of the power system. However, from the long-term operation experience, the following problems affect the normal operation of the traveling wave fault location device: ①The GPS signal is lost or the error is large; ②The communication is not smooth; ③Due to the reasons of operation and management, it is difficult to achieve distance measurement in a few places in a dual-terminal manner. The existence of the above-mentioned problems not only reduces the reliability, but also increases the daily maintenance workload of the ranging system.

In order to solve the problems existing in the operation of existing distance measuring devices and the problem that intelligent substations cannot realize double-terminal ranging at the present stage, it is necessary to develop a reliable and effective single-ended traveling wave ranging algorithm, while the existing single-ended impedance method or Both single-ended traveling wave methods have problems in terms of reliability or ranging accuracy.

Invention content:

Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a fault location method based on single-end distance measurement, which can improve the reliability of transmission line single-end fault distance measurement on the basis of ensuring the distance measurement accuracy.

The fault location method based on single-ended ranging provided by the present invention, the method is to check whether a short circuit occurs in the transmission line, and its improvement is that,

1) When a short circuit is found, use the transmission line traveling wave fault location device to measure the power frequency electrical quantity of the M-side bus at the local end of the transmission line, and estimate the transition resistance value;

2) According to the data of the power frequency electrical quantity in step 1), analyze the transient voltage/current traveling wave by wavelet transform, and judge that the fault is a common short-circuit fault or a special short-circuit fault;

3) If the result of step 2) is an ordinary short-circuit fault, then the single-ended traveling wave method combined with the line length is used to directly calculate the fault point location;

4) If the result of step 2) is a special short-circuit fault, the location of the fault point is calculated using the transmission line single-ended fault location method combining the impedance method and the traveling wave method.

The fault location method of the first preferred solution provided by the present invention is improved in that the single-ended traveling wave ranging method in combination with the line length in the step 3) includes the following steps:

① In the case of the short circuit, the original waveform of the fault current is obtained, the wavelet transform is performed on the fault current to obtain the maximum value of the wavelet transform modulus, and the amplitude screening is performed on the maximum value of the wavelet transform modulus to obtain the maximum value of the fault phase modulus after primary selection, and then Combined with the line length to filter out the required modulus maximum value;

②According to the modulus maxima screened out in step ①, calculate the time t ₀ for the fault initial wave head to reach the M terminal, the time t ₁ for the fault reflected wave head to reach the M terminal, and the reflected wave head for the N-terminal busbar at the opposite end of the transmission line Time t ₂ of reaching the M terminal;

③ Calculate the distance between the fault point and the M terminal according to the difference between the time t ₁ and the time t ₀

④ Calculate the distance between the fault point and the N terminal according to the difference between the time t ₂ and the time t ₀

5. According to the _l1 of the step 3., the _l2 of the step 4. and the total length L of the transmission line, the range of the fault point is obtained: d∈( _Ll1 , _Ll2 );

⑥ Obtain the fault point according to the step ⑤.

The fault location method of the second preferred solution provided by the present invention is improved in that the step 4) the transmission line single-ended fault location method combining the impedance method and the traveling wave method includes the following steps:

A. When the line is short-circuited, the fault traveling wave is measured by the transmission line traveling wave fault distance measuring device, and the wavelet analysis is carried out to the fault traveling wave to obtain the maximum value of the fault phase traveling wave mode;

B. according to the maximum value of the fault phase traveling wave mode obtained in step A, calculate the time t ₃ when the initial wave head of the fault arrives at the said M end and the time t ₄ when the reflected wave head arrives at the said M end;

C. Calculate the distance between the fault point and the M terminal according to the difference between the time _t4 and the time _t3

D. according to the transition resistance value of step 2) of claim 1, when being less than 150 ohms, it is low-resistance grounding, then choosing the fault interval is D ∈ (l ₃ -5% L, l ₃ +5% L); greater than 150 ohms When it is high-impedance grounding, the fault interval is selected as D∈(l ₃ -15%L, l ₃ +15%L);

E. According to the result of step D, combined with the wavelet transform modulus maximum value to determine the fault point.

The improvement of the fault location method of the third preferred solution provided by the present invention is that the power frequency electrical quantity in the step 1) includes three-phase current and three-phase voltage.

The fault location method of the fourth preferred solution provided by the present invention is improved in that the special short-circuit fault described in step 4) includes: 1. the N end is a terminal substation, and there is no branch line; 2. high resistance or low resistance Ground Fault.

The improvement of the fault location method of the fifth preferred solution provided by the present invention is that the calculation method for estimating the transition resistance value in step 1) is:

In the case of a phase-to-ground short-circuit fault on a transmission line fault, the phase voltage is as follows:

U＝IZ ₁ +I ₀ kZ ₁ +R _f I _f (1)

Among them: K is the zero-sequence compensation coefficient, K=(Z ₀ -Z ₁ )/Z ₁ ; Z ₁ is the positive sequence impedance; R _f is the transition resistance; I _f is the short-circuit current; I _f =I/C _m ;

Where: C _m is the shunt coefficient at the M end; $C_m=\frac{Z_{\mathrm{no}}+Z\&Center\; Dot;(L-l_3)}{Z_m+Z_{\mathrm{no}}+Z\&Center\; Dot;L}---\left(2\right)$

为所述M端的系统阻抗，Z_n为线路N端的系统阻抗，Z为单位长度的线路阻抗；L为线路总长，l₃为故障点到所述M端的距离；in

For the system impedance of the M end, Z _is the system impedance of the N end of the line, and Z is the line impedance of the unit length; L is the total length of the line, and ₁₃ is the distance from the point of failure to the M end;

The impedance of the N-terminal system is approximately taken as Z _n ≈ Z _m , then:

U＝(I+I ₀ k)Z ₁ +R _f I/C _m (3)

It can be obtained from formula 1:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; [</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; k</span>}\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; I</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

The improvement of the preferred solution of the fault location method provided by the present invention lies in that said ⑥ uses the single-ended impedance method to calculate the location of the fault point according to said step ⑤.

Compared with the prior art, the beneficial effects of the present invention are:

reliable. The invention combines the impedance method with the traveling wave method, completes transition resistance estimation and preliminary fault location by the single-end impedance method, and assists the single-end traveling wave method to complete fault distance measurement. Since the single-end impedance method has relatively high reliability, the reliability of the single-end ranging method is guaranteed as a whole.

precise. The invention utilizes the single-end traveling wave method to ensure the accuracy of fault distance measurement, and the distance measurement accuracy of the single-end traveling wave method can reach within 500m, and the distance measurement accuracy is not affected by factors such as line length.

Adaptable. The invention can adapt to distance measurement under different fault types, and is basically not affected by factors such as transition resistance, line structure, system operation mode and the like.

Description of drawings

FIG. 1 is a flow chart of the fault location method based on single-ended ranging provided by the present invention.

Fig. 2 is a schematic diagram of the simulation system model of the single-ended traveling wave ranging method combined with the line length provided by the present invention.

Fig. 3 is the actual fault current and wavelet transform modulus maxima of the simulation system model of the single-ended traveling wave ranging method combined with the line length in the case of common faults provided by the present invention.

Fig. 4 is a schematic diagram of the impedance method distance measurement provided by the present invention.

Fig. 5 is the actual fault data verification provided by the present invention.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a flowchart of this embodiment. First of all, when the transmission line fails, the transmission line traveling wave fault location device measures the power frequency electrical quantity of the M-side bus of the transmission line, determines the range of the fault point through the impedance method, and estimates the transition resistance value; according to the data of the power frequency electrical quantity, Analyze the transient voltage/current traveling wave by wavelet transform, and judge whether the fault is a common short-circuit fault or a special short-circuit fault; if it is a common short-circuit fault, use the single-ended traveling wave method combined with the line length to directly calculate the location of the fault point; if it is a special short-circuit fault If there is a fault, the single-ended fault location method of the transmission line combined with the impedance method and the traveling wave method is used to calculate the location of the fault point.

(1) The single-ended traveling wave ranging method combined with the line length, as shown in Figure 2.

In the figure, it is assumed that a short-circuit fault occurs at point G, and the excessive resistance is R _f . Fault point G produces current traveling waves i ₁ and i ₂ moving to both ends of the line.

1: The time from the beginning of the measurement to the arrival of the initial traveling wave of the fault at the M terminal is t ₀ , that is, the time when the current traveling wave i ₁ reaches the M terminal.

2: The reflected current traveling wave i′ ₁ reflected at the M terminal will generate a reflected current traveling wave i′ _f after reaching the fault point, and the time for the reflected current traveling wave i′ _f to reach the M terminal is t ₁ .

3: The current traveling wave i ₂ generated by the fault point G moves to the N terminal of the bus bar, and after reaching the N terminal, a transmitting traveling wave i′″ _f is generated, and the time for i′″ _f to reach the M terminal is t ₂ .

In this embodiment, point M is the local end of the transmission line, and point N is the opposite end of the transmission line. i′ _f is the reflected wave of the fault point, and the distance l ₁ between the short-circuit point and the M terminal can be calculated according to the arrival time difference between the initial fault wave head and the fault point reflected wave head; while i′″ _f is the reflected wave of the N-end bus, according to The arrival time difference between the head and the N-terminal bus reflected wave can be calculated as the distance l ₂ from the short-circuit point to the N-terminal, and at the same time, the total length of the transmission line is L≈l ₁ +l ₂ .

故障点距N端的距离

从而可以得出故障点所在范围：D∈(L-l₁，L-l₂)。The wavelet transform is performed on the original waveform of the fault current to obtain the maximum value of the wavelet transform modulus, and the amplitude screening of the wavelet transform modulus is performed to obtain the maximum value of the fault phase modulus after the primary selection, and then the required modulus maximum value is screened out in combination with the line length. Calculate the time t ₀ for the fault initial wave head to reach the M terminal, the time t ₁ for the fault reflected wave head to reach the M terminal, and the time t ₂ for the fault reflected wave head to reach the M terminal according to the modulus maximum value. The distance from the fault point to the M terminal

Distance from fault point to N terminal

Thus, the range of the fault point can be obtained: D∈(Ll ₁ , Ll ₂ ).

The application of this method is analyzed in combination with a set of actual fault data. The fault data is the M-side data of Liaoning Lihun Line on September 13, 2006. Line conditions: The total length of the line L: 41.723km. Due to the influence of waveform oscillation, the existing single-ended ranging program cannot accurately locate the fault point. Use the single-ended traveling wave ranging method combined with the line length to solve this problem. The specific steps are:

After a short circuit occurs on the transmission line, in the case of ordinary faults, within 2×L/v (L is the total length of the line, v is the wave velocity) after the initial moment of the fault, on the installation side (M terminal) of the transmission line traveling wave fault location device ) should be able to detect the reflected wave head of the fault point and the reflected wave head of the busbar at the opposite end in the transient traveling wave collected.

确定l₁为10.53km，l₂为32.9km。l₁和l₂之和接近线路全长L：41.723km，可确定故障范围为D∈(L-l₁，L-l₂)米。采用单端阻抗法计算故障点位置，确定故障点为距M端10.53km。最后，实际故障巡线结果为10.611km，与测距结果基本相符。According to the calculation formula is

It is determined that l ₁ is 10.53km and l ₂ is 32.9km. The sum of l ₁ and l ₂ is close to the total length of the line L: 41.723km, and the fault range can be determined to be D∈(Ll ₁ , Ll ₂ ) meters. The location of the fault point is calculated using the single-ended impedance method, and the fault point is determined to be 10.53km away from the M terminal. Finally, the actual fault line inspection result is 10.611km, which is basically consistent with the distance measurement result.

(2) Transmission line single-ended fault location method combined with impedance method and traveling wave method

Another function of the impedance method is to provide estimation of the transition resistance. In the present invention, the magnitude of the transition resistance is estimated by the shunt coefficient Cm. Considering the influence of sound mutual inductance, the zero-sequence compensation coefficient is used in the algorithm to equivalent the influence of line mutual inductance.

The calculation method for estimating the transition resistance value is:

When a faulty phase (assumed to be phase A) of the transmission line is grounded and short-circuited, the voltage of phase A is as follows:

U _a ＝I _a Z ₁ +I ₀ kZ ₁ +R _f I _f (1)

Where k is the zero-sequence compensation coefficient, k=(Z ₀ -Z ₁ )/Z ₁ , Z ₁ is the positive sequence impedance, R _f is the transition resistance, and I _f is the short-circuit current. In the case of ignoring the distributed capacitance to the ground, it can be obtained: _If =I _a /C _m ; where C _m is the shunt coefficient of the M terminal of the local terminal:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; \&CenterDot;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

为测量端的系统阻抗，Z_n为线路N端的系统阻抗，Z为单位长度的线路阻抗。in

is the system impedance at the measuring end, Z _n is the system impedance at the N end of the line, and Z is the line impedance per unit length.

L is the total length of the line, and d is the distance from the fault point to the M terminal, which can be calculated by the impedance method. The N-terminal system impedance is approximately taken as Z _n ≈ Z _m , then:

U _a ＝(I _a +I ₀ k)Z ₁ +R _f I _a /C _m (3)

It can be obtained from formula 1:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; [</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; k</span>}\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; Z</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

When the impedance method is used in combination with the traveling wave method, the main function of the impedance method is to provide an approximate fault range. For the traveling wave method, a time window is set, and the traveling wave head is screened within this time window. The size of the time window is related to Corresponding to the ranging error of the impedance method, according to the modulus maximum value of the fault phase traveling wave, it can be obtained: the time from the beginning of the measurement to the fault initial traveling wave arriving at the M terminal is t ₃ , and the time for the fault point reflected wave reaching the M terminal is t ₄ . The distance between the short-circuit point and the M terminal can be obtained by calculating the arrival time difference between the initial wave head of the fault and the reflected wave head of the fault point

Assume that the distance from the end M is l ₃ and the total length of the line is L. When R _f is less than 150 ohms, it is low-resistance grounding, and the selected fault interval is D∈(l ₃ -5%L, l ₃ +5%L). When R _f is greater than 150 ohms, it is high-impedance grounding, and the selected fault interval is D∈(l ₃ -15%L, l ₃ +15%L). Combined with wavelet transform modulus maximum value to determine the fault point.

The application of this method is analyzed in combination with a set of actual fault data. On March 20, 2010, there was a fault on the Liaoning Qingxin Line. The actual line fault was 40.2km away from the M terminal, but there was a branch line with a length of 28.2km, which affected the calculation of the existing single-end ranging program. Using the single-end fault location method of the transmission line combined with the impedance method and the traveling wave method in this embodiment, the distance from the M terminal of the impedance method is 39km, and the transition resistance is not greater than 100Ω. Therefore, the reflected wave of the fault point is selected for distance measurement. , the distance between the final ranging result and the M terminal: 40.9km, which is basically consistent with the line inspection result.

Finally, it should be noted that: the combination of the above embodiments only illustrates the technical solution of the present invention rather than limiting it. Those of ordinary skill in the art should understand that: those skilled in the art can make modifications or equivalent replacements to the specific embodiments of the present invention, but these modifications or changes are all within the protection scope of the pending claims.

Claims (7)

1. based on the Fault Locating Method of single end distance measurement, described method is to check whether transmission line of electricity is short-circuited, and it is characterized in that,

When 1) finding short circuit, measure the power frequency electric parameters that transmission line of electricity local terminal M holds bus, estimation transition resistance value with the transmission line travelling wave fault location device;

2) according to the data of the described power frequency electric parameters of step 1), combined with wavelet transformed is analyzed transient voltage/current traveling wave, and failure judgement is common short trouble or special short trouble;

3) as step 2) the result be common short trouble, then adopt the single-ended traveling wave method of combined circuit length directly to calculate position of failure point;

4) as step 2) the result be special short trouble, then adopt the transmission line of electricity one-end fault ranging method that impedance method combines with traveling wave method to calculate position of failure point.

2. Fault Locating Method as claimed in claim 1 is characterized in that, the single-ended traveling wave telemetry of the described combined circuit length of described step 3) comprises the steps:

1. under the described short-circuit conditions, obtain the fault current original waveform, fault current is carried out wavelet transformation obtain the wavelet transformation modulus maximum, the wavelet transformation modulus maximum is carried out fault phase modulus maximum after amplitude screening obtains primary election, combined circuit length filters out the modulus maximum that needs then;

2. the modulus maximum that 1. filters out according to step calculates the time t that the initial wave head of fault arrives described M end ₀, fault reflection wave head arrives the time t of described M end ₁, transmission line of electricity opposite end N end bus reflection wave head arrives the time t of described M end ₂

3. according to described time t ₁With described time t ₀Difference calculate the distance of trouble spot apart from described M end

4. according to described time t ₂With described time t ₀Difference calculate the distance of trouble spot apart from described N end

5. according to described step described l 3. ₁, described step described l 4. ₂With the total length L of transmission line of electricity, draw the trouble spot in-scope: d ∈ (L-l ₁, L-l ₂);

6. 5. obtain the trouble spot according to described step.

3. Fault Locating Method as claimed in claim 1 is characterized in that, the transmission line of electricity one-end fault ranging method that the described impedance method of described step 4) combines with traveling wave method comprises the steps:

A. during line short, described transmission line travelling wave fault location device records fault traveling wave, fault traveling wave is carried out wavelet analysis obtain fault and go the maximum value of mode mutually;

B. the fault that obtains according to steps A is gone the maximum value of mode mutually, calculates the time t that the initial wave head of fault arrives described M end ₃Arrive the time t that described M holds with the reflection wave head ₄

C. according to described time t ₄With described time t ₃Difference calculate the distance of trouble spot apart from described M end

D. according to the step 2 of claim 1) the transition resistance value, be low-impedance earthed system during less than 150 ohm, then choosing fault section is D ∈ (l ₃-5%L, l ₃+ 5%L); Be high resistance ground during greater than 150 ohm, then choosing fault section is D ∈ (l ₃-15%L, l ₃+ 15%L);

E. according to the result of step D, the localization of faults of combined with wavelet transformed modulus maximum.

4. Fault Locating Method as claimed in claim 1 is characterized in that, the described power frequency electric parameters of described step 1) comprises three-phase current and three-phase voltage.

5. Fault Locating Method as claimed in claim 1 is characterized in that, the described special short trouble of described step 4) comprises: the 1.N end is terminal transformer station, no branched line; 2. high resistant or low-impedance earthed system fault.

6. Fault Locating Method as claimed in claim 1 is characterized in that, the computing method of the described estimation transition resistance of described step 1) value are:

Under transmission line malfunction phase ground short circuit failure condition, phase voltage is shown below:

U＝IZ ₁+I ₀kZ ₁+R _fI _f (1)

Wherein: K is the zero sequence compensation coefficient, K=(Z ₀-Z ₁)/Z ₁Z ₁Be positive sequence impedance; R _fBe transition resistance; I _fBe short-circuit current; I _f=I/C _m

Wherein: C _mDiverting coefficient for the M end; $C_m=\frac{Z_n+Z\&CenterDot;(L-l_3)}{Z_m+Z_n+Z\&CenterDot;L}---\left(2\right)$

Wherein

Be the system impedance of described M end, Z _nBe the system impedance of circuit N end, Z is the line impedance of unit length; L is the circuit length overall, l ₃Be the distance of trouble spot to described M end;

The approximate Z that gets of described N end system impedance _n≈ Z _m, then:

U＝(I+I ₀k)Z ₁+R _fI/C _m (3)

Can get by formula 1:

$R_f=C_m[\frac{U}{I}(1+k\frac{I_0}{I})-Z_1]---\left(4\right)$

7. Fault Locating Method as claimed in claim 2 is characterized in that, describedly 6. 5. adopts the single-ended impedance method to calculate position of failure point according to described step.

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