CN103364691A - Distributed fault location method for overhead line-cable hybrid circuit - Google Patents

Abstract

The invention discloses a distributed fault location method for an overhead line-cable hybrid circuit. The method comprises the following steps: S1, arranging fault traveling wave detection devices at the joint of the hybrid circuit and a bus and the joints of different circuits in the hybrid circuit, judging a failed circuit according to the polarity of a first fault travelling wave head detected by each fault traveling wave detection device, wherein when fault current travelling wave heads detected by two adjacent fault travelling wave detecting devices are of opposite polarities, a circuit between the two adjacent fault travelling wave detection device is the failed circuit; and S2, judging the source of a second travelling wave head according to the arriving time of the fault travelling wave heads detected by the fault travelling wave detection devices at the two ends of the failed circuit, and selecting a proper fault location method for positioning. According to the distributed fault location method, online calculation of the travelling wave transmission speed of a power transmission line is realized, and the source of a second fault travelling wave of a detection point is judged according to the analysis of a travelling wave sequence; and the method has a good application prospect.

Description

A kind of overhead lines combined with cable distributed fault distance-finding method

Technical field

The present invention relates to a kind of overhead lines combined with cable distributed fault distance-finding method based on fault current wavefront information.

Background technology

The highdensity zone of loading in the city, the land resource pretty valuable, because overhead transmission line corridor floor area is larger, the exploitation urban underground space, cabling becomes a pith of power grid construction.City cable rationally utilizes urban underground space, has alleviated the contradiction of urban development and shortage of land resource, and land utilization ratio is improved.

In a single day although city cable is more reliable than pole line, laid down cost is higher, and breaks down, the trouble spot is difficult finds that inconvenience is in time processed, and maintenance cost is not low yet.Therefore most cities has adopted the mode of overhead lines combined with cable, averages out in factors such as city space and laid down costs.Yet the problem that this balance is brought is that the distribution parameter of pole line and cable is inconsistent, in case transmission line of electricity breaks down, traditional fault distance-finding method can't be suitable for, and need to study in light of the circumstances.

The row velocity of wave propagation is relevant with the circuit medium, and is irrelevant with the material of heart yearn.Row wave speed v computing formula is:

$v=\frac{1}{\sqrt{L_0{C}_0}}=\frac{C}{\sqrt{{\mathrm{\ϵ}}_{\mathrm{\γ}}{\mathrm{\μ}}_{\mathrm{\γ}}}}---\left(1\right)$

In the formula, L ₀, C ₀Be respectively the corresponding inductance of transmission line of electricity and electric capacity, C is the light velocity, ε _γBe the relative dielectric constant of heart yearn surrounding medium, μ _γRelative permeability for the heart yearn surrounding medium.Because the difference of cable and aerial wire laying environment and circuit material, both specific inductive capacity are different with magnetic permeability, cause pole line and cable to have different velocities of wave.

Under the perfect condition, relative dielectric constant and the relative permeability of air are 1, so the wave velocity of pole line is similar to the light velocity.For cable line, its relative dielectric constant is about 4, and magnetic permeability is about 1, so the velocity of wave of cable is about the light velocity half.

Surge impedance of a line also has relation with specific inductive capacity and the magnetic permeability of circuit, and the wave impedance of general pole line is about 500 Ω, and the wave impedance of cable line is about several Europe between tens Europe.Therefore joint line is at the tie point place of pole line and cable, and wave impedance is discontinuous, and catadioptric can occur fault traveling wave, and is accompanied by capable wave attenuation, so that fault traveling wave wave head impalpable.

As the above analysis, after mixed power transmission line breaks down, can produce the fault traveling wave that propagate at road direction along the line two ends, catadioptric not only can occur at the bus place in fault traveling wave, also catadioptric can occur at the joint line tie point.The below breaks down the capable ripple of analysis of failure with cable in the joint line or pole line respectively.

1, cable breaks down

As shown in Figure 1, cable F point breaks down, and P, Q are respectively the tie point of cable two ends and pole line.If P, Q the capable ripple pick-up unit of fault current is installed at 2, then its first fault traveling wave that detects is the fault traveling wave that the trouble spot directly is transmitted to check point, and second capable ripple might be the reflection wave through pole line, also might be the reflection wave of cable opposite end, or the reflection wave of trouble spot.

If the fault initial time is 0, the failure cable total length is L ₂, left frame ceases to be busy length is L ₁, the length of left side frame ceases to be busy is L ₃, trouble spot F and P point distance are L _PThen P, Q both sides above-mentioned each row ripple that can detect is time of arrival:

$\left\{\begin{array}{c}{t}_{P1}=\frac{L_P}{v_b}\\ t_{P2}=\frac{L_P}{v_b}+\frac{{2L}_1}{v_a}\\ t_{P3}=\frac{{2L}_2-L_P}{v_b}\\ t_{P4}=\frac{3L_P}{v_b}\end{array}\right.---\left(2\right)$

$\left\{\begin{array}{c}{t}_{Q1}=\frac{L_2-L_P}{v_b}\\ t_{Q2}=\frac{L_2-L_P}{v_b}+\frac{{2L}_3}{v_a}\\ t_{Q3}=\frac{L_2+L_P}{v_b}\\ t_{Q4}=\frac{3(L_2-L_P)}{v_b}\end{array}\right.---\left(3\right)$

The reflection wave of trouble spot and cable opposite end can occur in the faulty line upper semisection or lower semisection is judged by fault.When fault occurs in the cable upper semisection, namely the trouble spot is near P point, L _P＜L ₂/ 2 o'clock, by formula (2) and (3) as can be known, t _P4＜t _P3, t _Q4＞t _Q3, arrive first the P point at the reflection wave of the traveling-wave ratio cable opposite end of P point failure point reflection.Equally, when fault occurs in the cable lower semisection, namely the trouble spot is near Q point, L _P＞L ₂/ 2 o'clock, arrive first than cable opposite end reflection wave for the trouble spot transmitted wave at the Q point.

Therefore, with the analytic target of attaching most importance near the check point of trouble spot, then the reflection wave of trouble spot always arrives first than cable opposite end reflection wave.If the pole line wave velocity is v _a, cablebreak speed is v _b, then can obtain as drawing a conclusion by the analysis to each wavefront time of arrival:

When fault occurs in the cable upper semisection, if L ₁/ v _a＞L _P/ v _b, then the reflection wave of trouble spot arrives first the P point; If L ₁/ v _a＜L _P/ v _b, then the reflection wave through pole line arrives first the P point.

When fault occurs in the cable lower semisection, if L ₃/ v _a＞(L ₂-L _P)/v _b, then the reflection wave of trouble spot arrives first the Q point; If L ₃/ v _a＜(L ₂-L _P)/v _b, then the reflection wave through pole line arrives first the Q point.

2, pole line breaks down

As shown in Figure 2, pole line F point breaks down, A, B are respectively the tie point of pole line and cable, and be separately installed with the capable ripple pick-up unit of fault current, then its fault traveling wave that detects also has Four types, is respectively the trouble spot and directly is transmitted to the fault traveling wave of check point, reflection wave, the reflection wave of pole line opposite end or the reflection wave of trouble spot of process cable.The fault traveling wave of directly propagating except the trouble spot can be defined as the capable ripple of first arrival, and the priority of other row ripples arrival check points all is uncertain.

If the fault initial time is 0, the pole line total length is L ₂, the left side cable length is L ₁, the right side cable length is L ₃, trouble spot F and A point distance are L _AThen A, B both sides each row ripple that can detect is time of arrival:

$\left\{\begin{array}{c}{t}_{A1}=\frac{L_A}{v_b}\\ t_{A2}=\frac{L_A}{v_b}+\frac{{2L}_1}{v_a}\\ t_{A3}=\frac{{2L}_2-L_A}{v_b}\\ t_{A4}=\frac{{3L}_A}{v_b}\end{array}\right.---\left(4\right)$

$\left\{\begin{array}{c}{t}_{B1}=\frac{L_2-L_A}{v_b}\\ t_{B2}=\frac{L_2-L_A}{v_b}+\frac{{2L}_3}{v_a}\\ t_{B3}=\frac{L_2+L_A}{v_b}\\ t_{B4}=\frac{3(L_2-L_A)}{v_b}\end{array}\right.---\left(5\right)$

The reflection wave of trouble spot and cable opposite end can occur in the faulty line upper semisection or lower semisection is judged by fault.Utilize the same method of cable fault to analyze: with the analytic target of attaching most importance near the check point of trouble spot, then the reflection wave of trouble spot always arrives first than cable opposite end reflection wave.

If the pole line wave velocity is v _a, cablebreak speed is v _b, then can obtain as drawing a conclusion by the analysis to each wavefront time of arrival:

When fault occurs in the pole line upper semisection, if L ₁/ v _b＞L _A/ v _a, then the reflection wave of trouble spot arrives first the A point; If L ₁/ v _b＜L _A/ v _a, then the reflection wave through pole line arrives first the A point.

When fault occurs in the pole line lower semisection, if L ₃/ v _b＞(L ₂-L _A)/v _a, then the reflection wave of trouble spot arrives first the B point; If L ₃/ v _b＜(L ₂-L _A)/v _a, then the reflection wave through pole line arrives first the B point.

Existing mixed line fault distance-finding method mainly contains the wave velocity normalization method.Joint line is reduced to uniline carries out fault localization, and then convert back joint line, the method needs repeatedly conversion, and error is larger.And the tie point voltmeter algorithm that is developed by traditional fault analytical method, determine fault section by the voltage that calculates tie point, and then by an iterative distance that is out of order, the method is only suitable for joint line simple in structure, replace the joint line that occurs for power cable, pole line, the method is calculated too complicated, and error can increase and increase along with circuit.The capable ripple time difference method that is developed by traveling wave method is relatively accurately simple, the mistiming that arrives two ends by fault traveling wave is determined first faulty line, then accurately locate according to single-ended or both-end method, yet because the joint line wave process is complicated, the method is difficult to consider the reflection of row setback comprehensively.

Summary of the invention

The problem that exists in order to solve above-mentioned prior art, the present invention aims to provide a kind of pole line and cable hybrid line distributed fault distance-finding method, take the polarity of traveling wave that detects as criterion, then the failure judgement circuit accurately locates according to detecting the time that wavefront arrives.

Technical solution of the present invention is as follows:

A kind of pole line and cable hybrid line distributed fault distance-finding method may further comprise the steps:

Step S1, junction at joint line and bus, and the tie point place of different circuits arranges the fault traveling wave pick-up unit in the joint line, the polarity of the first fault traveling wave wave head that detects according to each fault traveling wave pick-up unit, judge the circuit that breaks down, the polarity of the fault current wavefront that detects when two adjacent fault traveling wave pick-up units is opposite, and then the circuit between these two adjacent fault traveling wave pick-up units is the circuit that breaks down;

Step S2 according to the time of arrival of the detected fault traveling wave wave head of fault traveling wave pick-up unit at the circuit two ends of breaking down, judges the source of second wavefront, then selects suitable fault distance-finding method to position.

Described step S2 specifically comprises the steps:

A) detect the priority of fault current according to the fault traveling wave pick-up unit at the circuit two ends of breaking down, failure judgement occurs in the orientation of this circuit:

A certain fault traveling wave pick-up unit when the circuit two ends of breaking down detects first fault current, and then fault occurs in the orientation near this fault traveling wave pick-up unit;

Fault traveling wave pick-up unit when the circuit two ends of breaking down detects fault current simultaneously, and then fault occurs in the center of this section circuit;

B) detect time of the capable ripple of fault current according to the fault traveling wave pick-up unit at the circuit two ends of breaking down, calculate the general distance of the capable ripple check point of fault nidus distance fault:

If the circuit two ends P that breaks down and Q point detect the moment of fault current and are respectively t _P1And t _Q1, the initial time that fault occurs is t ₀, then calculating trouble spot distance fault check point P distance, formula is as follows:

$L_P=\frac{\mathrm{\Δ}{t}_{P1}}{\mathrm{\Δ}{t}_{P1}+{\mathrm{\Δt}}_{Q1}}\·L_2$

Wherein, Δ t _P1For fault traveling wave is transferred to needed time of P, Δ t _Q1For fault traveling wave is transferred to needed time of Q point, L ₂Be faulty line total length, L _PDistance for the capable ripple check point of trouble spot distance fault P;

C) judge the source of the capable ripple of second failure that detects according to the Position Approximate of trouble spot and the length of faulty line both sides All other routes, and accurately locate:

With the capable ripple check point of the nearer fault current of the distance fault point analytic target of attaching most importance to, according to the general distance of the capable ripple check point of fault nidus distance fault of Primary Location, the reflection wave of failure judgement point and through adjacent lines by the sequencing of the capable ripple arrival check point of opposite end tie point or bus reflection;

If the reflection wave of trouble spot arrives first the check point place of selective analysis, then calculated the capable wave-wave speed of fault initial time and faulty line time of arrival by the first two wavefront of check point, obtain thus accurate localization of fault result;

If adjacent lines opposite end tie point or bus reflection wave at first arrive check point, then calculate the capable wave-wave speed of adjacent lines time of arrival according to the first two wavefront of selective analysis check point, then receive the time of fault Mintrop wave according to adjacent lines opposite end check point, calculate the position of trouble spot, the general distance of the capable ripple check point of fault nidus distance fault of the position of the trouble spot of this location and Primary Location is averaged, obtain final accurate localization of fault result.

Pole line of the present invention and cable hybrid line distributed fault distance-finding method by detecting of each check point fault current polarity discriminating faulty line, then according to faulty line both sides check point detect the first two wavefront accurately locate time of arrival, be implemented in the traveling wave speed of line computation transmission line of electricity, and analyze the source of second failure current traveling wave, preferably application prospect is arranged.

Description of drawings

Mixed line fault travelling wave analysis chart when Fig. 1 is cable fault;

Mixed line fault travelling wave analysis chart when Fig. 2 is the pole line fault;

Fig. 3 is the joint line system diagram.

Embodiment

Below in conjunction with accompanying drawing, provide preferred embodiment of the present invention, and be described in detail.

A kind of pole line and cable hybrid line distributed fault distance-finding method may further comprise the steps:

Step S1, the polarity of the first fault traveling wave wave head that the fault traveling wave pick-up unit of installing according to each tie point of joint line and bus place detects is judged the circuit that breaks down.

Described step S1 specifically comprises:

After transmission line of electricity breaks down, can produce the fault traveling wave of road direction along the line two ends transmission.The current traveling wave direction that the fault current detection device of fault both sides detects is opposite, and the capable ripple of the fault current that the fault homonymy detects, its direction is identical.The circuit that namely detects between opposite adjacent two the fault current detection devices of fault current polarity of traveling wave is the circuit that breaks down.

Step S2 according to the detected fault traveling wave wave head of the check point time of arrival at the circuit two ends of breaking down, judges the source of second wavefront, then selects suitable Fault Location Algorithm to position.

Described step S2 specifically comprises:

1, the priority failure judgement that detects fault current according to the faulty line two ends occurs in upper semisection or the lower semisection of circuit.

Owing to being consistent in same circuit upward traveling wave wave velocity, therefore successively can judging fault according to the capable ripple arrival of fault current faulty line two ends and occur in upper semisection or lower semisection.If two ends detect the capable ripple of fault current simultaneously, then fault occurs in the circuit mid point.

2, detect the time of the capable ripple of fault current according to two ends, calculate the Position Approximate that fault occurs.

No matter fault occurs in which position of faulty line, velocity of wave one regularly, fault traveling wave is transferred to the time sum at faulty line two ends and fixes.

When cable broke down, as shown in Figure 1, establishing the moment that failure cable both sides P, Q check point detect fault current was t _P1And t _Q1, the initial time that fault occurs is t ₀, following equation is then arranged:

$\left\{\begin{array}{c}{\mathrm{\Δt}}_{P1}+{\mathrm{\Δt}}_{Q1}=L_2/v_b=C_1\\ {\mathrm{\Δt}}_{P1}-{\mathrm{\Δt}}_{Q1}=t_{P1}-t_{Q1}=\mathrm{\Δt}\end{array}\right.---\left(7\right)$

Wherein, Δ t _P1With Δ t _Q1For fault traveling wave is transferred to P and needed time of Q point, Δ t is the mistiming of the capable ripple of first fault current that detects of P, Q point.Can calculate Δ t according to formula (7) _P1With Δ t _Q1, the general distance that can calculate thus trouble spot distance P point is:

$L_P=\frac{{\mathrm{\Δt}}_{P1}}{{\mathrm{\Δt}}_{P1}+{\mathrm{\Δt}}_{Q1}}\·L_2---\left(8\right)$

Equally, when pole line breaks down, following equation is arranged also:

$\left\{\begin{array}{c}{\mathrm{\Δt}}_{A1}+{\mathrm{\Δt}}_{B1}=L_2/v_a=C_1\\ {\mathrm{\Δt}}_{A1}-{\mathrm{\Δt}}_{B1}=t_{A1}-t_{B1}=\mathrm{\Δt}\end{array}\right.---\left(9\right)$

The distance that can calculate trouble spot distance A point probably is

$L_A=\frac{{\mathrm{\Δt}}_{A1}}{{\mathrm{\Δt}}_{A1}+{\mathrm{\Δt}}_{B1}}\·L_2---\left(10\right)$

3, judge the source of the capable ripple of second failure that detects according to the Position Approximate of trouble spot and the length of faulty line both sides All other routes, and accurately locate.

When fault occurs in the cable upper semisection, the length of cable left side frame ceases to be busy is L ₃, the pole line wave velocity is v _a, cablebreak speed is v _b, as shown in Figure 1, following two kinds of situations are arranged:

A) work as L ₁/ v _a＞L _P/ v _bThe time, the trouble spot reflection wave at first arrives the P point, and this moment, the P point detected, and be t second wavefront time of arrival _P4, can get thus the fault initial time and be

$t_0=\frac{{3t}_{P1}-t_{P4}}{2}---\left(11\right)$

Can calculate the cable velocity of wave is

$v_b=\frac{L_2}{t_{P1}+t_{Q1}-{2t}_0}---\left(12\right)$

Can further revise position of failure point according to the capable wave-wave speed that online calculates

L _P＝v _b(t _P1-t ₀) (13)

B) work as L ₁/ v _a＜L _P/ v _bThe time, at first arriving the P point through the reflection wave of overhead transmission line, this moment, the P point detected, and be t second wavefront time of arrival _P2, the online velocity of wave that can get thus overhead transmission line is

$v_a=\frac{{2L}_1}{t_{P2}-t_{P1}}---\left(14\right)$

Can obtain following relation

$\left\{\begin{array}{c}(t_{P2}-t_0)+(t_{Q1}-t_0)=\frac{L_2}{v_b}+\frac{2L_1}{v_a}=C_2\\ t_{P2}-t_{Q1}=\frac{{2L}_1}{v_a}+\frac{{2L}_P-L_2}{v_b}=\mathrm{\Δ}{t}^{\′}\end{array}\right.---\left(15\right)$

The fault distance L that formula (15) is calculated _PThe fault distance that calculates with formula (8) carries out arithmetic mean, to reduce the error of range measurement system.

When fault occurs in the cable lower semisection, following two kinds of situations are arranged also:

A) work as L ₃/ v _a＞(L ₂-L _P)/v _bThe time, the trouble spot reflection wave at first arrives the Q point, and this moment, the Q point detected, and be t second wavefront time of arrival _Q4, can get thus the fault initial time and be

$t_0=\frac{{3t}_{Q1}-t_{Q4}}{2}---\left(16\right)$

Can calculate the cable velocity of wave is

$v_b=\frac{L_2}{t_{P1}+t_{Q1}-{2t}_0}---\left(17\right)$

Can further revise position of failure point according to the capable wave-wave speed that online calculates

L _P＝v _b(t _P1-t ₀) (18)

B) work as L ₃/ v _a＜(L ₂-L _P)/v _bThe time, the reflection wave of the opposite end check point of adjacent lines at first arrives the Q point, and this moment, the Q point detected, and be t second wavefront time of arrival _Q2, the online velocity of wave that can get thus overhead transmission line is

$v_a=\frac{{2L}_3}{t_{Q2}-t_{Q1}}---\left(19\right)$

Can obtain following relation

$\left\{\begin{array}{c}(t_{P1}-t_0)+(t_{Q2}-t_0)=\frac{L_2}{v_b}+\frac{{2L}_3}{v_a}=C_2\\ t_{Q2}-t_{P1}=\frac{{2L}_3}{v_a}+\frac{L_2-{2L}_P}{v_b}=\mathrm{\Δ}{t}^{\′}\end{array}\right.---\left(20\right)$

The fault distance L that formula (20) is calculated _PThe fault distance that calculates with formula (8) carries out arithmetic mean, to reduce the error of range measurement system.

When fault occurs in overhead transmission line, because analytical approach is in full accord, does not add at this and give unnecessary details.

Embodiment:

In PSCAD, set up as shown in Figure 2 overhead lines combined with cable model, this system is the 35kv Double-End Source, comprise three overhead transmission lines and three cables, pole line and cable be the interval successively, its length is respectively 60km, 40km, 50km, 50km, 40km, 60km, at each tie point and bus place the fault current detection device is installed all, the check point data sampling rate is 1MHz.

Embodiment 1:

Fault occurs on the hybrid circuit cable 1, and 0.245s broke down after system started, and was singlephase earth fault, and fault resstance is 50 ohm.Analyze by the fault traveling wave electric current that check point 1～7 is detected, it is as shown in table 1 to obtain its current polarity.

Each check point current polarity of table 1 is analyzed

Check point	1	2	3	4	5	6	7
								Polarity	+	+	-	-	-	-	-

Fault occurs between check point 2 and 3 as shown in Table 1, and namely cable 1.

Check point 2 detects first fault traveling wave time of arrival is 0.245200s, and check point 3 detects first fault traveling wave time of arrival is 0.245064s, so fault occurs in the lower semisection of cable 1.Set the cablebreak speed v _b=1.5 * 10 ⁸M/s, the pole line wave velocity is v _a=2.96 * 10 ⁸M/s then can get C thus ₁=267 μ s are so can calculate Δ t _P1=201.5 μ s, Δ t _Q1=65.5 μ s, can get the fault Position Approximate by formula (7) is the 9.813km place.Because pole line length is 50km, so second capable ripple detecting of check point 3 is from the reflection of trouble spot.Because the capable ripple of second of check point 3 time of arrival is 0.245201s, can calculate fault initial time t by formula (15) ₀=0.244998s can calculate v according to formula (16) and formula (17) again _b=1.52 * 10 ⁸M/s, L _P=9.904km.

Embodiment 2:

Fault occurs on the hybrid circuit pole line 3, and 0.240s broke down after system started, and was double earthfault, and fault resstance is 500 ohm.Analyze by the fault traveling wave electric current that check point 1～7 is detected, it is as shown in table 2 to obtain its current polarity.

Each check point current polarity of table 2 is analyzed

Check point	1	2	3	4	5	6	7
								Polarity	+	+	+	+	+	-	-

Fault occurs between check point 5 and 6 as shown in Table 2, and namely pole line 3.

Check point 5 detects first fault traveling wave time of arrival is 0.240030s, and check point 6 detects first fault traveling wave time of arrival is 0.240098s, so fault occurs in the upper semisection of pole line 3.Set the cablebreak speed v _b=1.5 * 10 ⁸M/s, the pole line wave velocity is v _a=2.96 * 10 ⁸M/s then can get C thus ₁=135 μ s are so can calculate Δ t _A1=33.5 μ s, Δ t _B1=101.5 μ s, can get the fault Position Approximate is the 9.926km place.Because cable 2 length are 50km, so second capable ripple detecting of check point 5 is from the reflection of trouble spot.Because the capable ripple of second of check point 5 time of arrival is 0.240098s, can calculate fault initial time t ₀=0.239996s can calculate v thus _a=2.94 * 10 ⁸M/s, L _A=10.000km.

Through a large amount of simulation results shows, this distance-finding method error maximum is no more than 150m.

Be noted that above enumerate only for specific embodiments of the invention, obviously the invention is not restricted to above embodiment, many similar variations are arranged thereupon.If those skilled in the art all should belong to protection scope of the present invention from all distortion that content disclosed by the invention directly derives or associates.

Claims (2)

1. overhead lines combined with cable distributed fault distance-finding method is characterized in that said method comprising the steps of:

Step S1, junction at joint line and bus, and the tie point place of different circuits arranges the fault traveling wave pick-up unit in the joint line, the polarity of the first fault traveling wave wave head that detects according to each fault traveling wave pick-up unit, judge the circuit that breaks down, the polarity of the fault current wavefront that detects when two adjacent fault traveling wave pick-up units is opposite, and then the circuit between these two adjacent fault traveling wave pick-up units is the circuit that breaks down;

Step S2 according to the time of arrival of the detected fault traveling wave wave head of fault traveling wave pick-up unit at the circuit two ends of breaking down, judges the source of second wavefront, then selects suitable fault distance-finding method to position.

2. joint line distributed fault distance-finding method according to claim 1 is characterized in that described step S2 specifically comprises the steps:

A) detect the priority of fault current according to the fault traveling wave pick-up unit at the circuit two ends of breaking down, failure judgement occurs in the orientation of this circuit:

A certain fault traveling wave pick-up unit when the circuit two ends of breaking down detects first fault current, and then fault occurs in the orientation near this fault traveling wave pick-up unit;

Fault traveling wave pick-up unit when the circuit two ends of breaking down detects fault current simultaneously, and then fault occurs in the center of this section circuit;

B) detect time of the capable ripple of fault current according to the fault traveling wave pick-up unit at the circuit two ends of breaking down, calculate the general distance of the capable ripple check point of fault nidus distance fault:

If the circuit two ends P that breaks down and Q point detect the moment of fault current and are respectively t _P1And t _Q1, the initial time that fault occurs is t ₀, then calculating trouble spot distance fault check point P distance, formula is as follows:

$L_P=\frac{\mathrm{\Δ}{t}_{P1}}{\mathrm{\Δ}{t}_{P1}+{\mathrm{\Δt}}_{Q1}}\·L_2$

Wherein, Δ t _P1For fault traveling wave is transferred to needed time of P, Δ t _Q1For fault traveling wave is transferred to needed time of Q point, L ₂Be faulty line total length, L _PDistance for the capable ripple check point of trouble spot distance fault P;

C) judge the source of the capable ripple of second failure that detects according to the Position Approximate of trouble spot and the length of faulty line both sides All other routes, and accurately locate:

With the capable ripple check point of the nearer fault current of the distance fault point analytic target of attaching most importance to, according to the general distance of the capable ripple check point of fault nidus distance fault of Primary Location, the reflection wave of failure judgement point and through adjacent lines by the sequencing of the capable ripple arrival check point of opposite end tie point or bus reflection;

If the reflection wave of trouble spot arrives first the check point place of selective analysis, then calculated the capable wave-wave speed of fault initial time and faulty line time of arrival by the first two wavefront of check point, obtain thus accurate localization of fault result;

If adjacent lines opposite end tie point or bus reflection wave at first arrive check point, then calculate the capable wave-wave speed of adjacent lines time of arrival according to the first two wavefront of selective analysis check point, then receive the time of fault Mintrop wave according to adjacent lines opposite end check point, calculate the position of trouble spot, the general distance of the capable ripple check point of fault nidus distance fault of the position of the trouble spot of this location and Primary Location is averaged, obtain final accurate localization of fault result.

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