CN104767183A - Method for recognizing different-phase cross-line ground fault of double-circuit lines based on actual measurement of voltage of different-phase cross-line grounding point - Google Patents

Abstract

The invention discloses a method for recognizing a different-phase cross-line ground fault of double-circuit lines based on actual measurement of the voltage of a different-phase cross-line grounding point. According to the method, whether the phase angle of the voltage drop from a return circuit protecting and setting range of the double-circuit line I on the same tower to the different-phase cross-line grounding fault point of the double-circuit line is superior to the zero-sequence current injected to the different-phase cross-line grounding fault point from a single end ranges from 180 degrees to 360 degrees, so that whether a movement trip signal is sent or not is determined; the influences of the factors such as the zero-sequence mutual inductance, transition resistance and load current between the lines and the operating mode of an electric power system on a fault recognition result are eliminated theoretically, it is guaranteed that no protective dead zone exists when the different-phase cross-line ground fault of the double-circuit lines occurs at an outlet in the forward direction, and it is also guaranteed that malfunctions are avoided when the different-phase cross-line ground fault of the double-circuit lines occurs at an outlet in the reverse direction. The method is suitable for electricity quantity backup protection of the single ends of the double-circuit lines on the same tower.

Description

Based on the non-same famous prime minister's cross-line ground fault recognition method of double-circuit line of non-same famous prime minister's cross-line ground actual measurement

Technical field

The present invention relates to Relay Protection Technology in Power System field, specifically relate to a kind of non-same famous prime minister's cross-line ground fault recognition method of double-circuit line based on non-same famous prime minister's cross-line ground actual measurement.

Background technology

Analyses for double circuits on same tower has that floor space is few, cost is low, connects operation of power networks reliable and stable, has become a kind of common transmission line connected mode of electric power system.Zero-sequence mutual inductance is there is between analyses for double circuits on same tower line; zero-sequence mutual inductance has an impact to zero-utility theory; and then generation additional impedance; the additional impedance caused because of zero-sequence mutual inductance can cause protector measuring to fault impedance be greater than physical fault impedance; when causing close protection seting scope place generation earth fault in analyses for double circuits on same tower protection zone; there is misoperation in protection, unfavorable to power network safety operation.

Even if analyses for double circuits on same tower occur through the direct earth fault of shaft tower, soil resistivity lower ground district's transition resistance also near 10 Ω; The local transition resistance higher in resistivity can reach 30 Ω, or even higher.The non-vanishing fault impedance that protective device is calculated of transition resistance, except comprising the fault impedance component of reaction true fault distance, further comprises the additional impedance produced because of transition resistance.The additional impedance that transition resistance produces is resistance sense or easily causes impedance ground distance protection tripping or steady-state in capacitance-resistance.False protection or tripping, can bring great loss to safe operation of power system, even likely can threaten the stability of electric power system.

Operating characteristics round edge circle of existing analyses for double circuits on same tower ground distance protection is through the origin of coordinates; because the origin of coordinates is positioned on operating characteristics round edge circle; during protection forward outlet earth fault there is dead band in protection; and along with transition resistance and load current increase, protection forward outlet dead band is larger.Because the origin of coordinates is positioned on operating characteristics round edge circle, there is the possibility of malfunction in protection in the other direction outlet earth fault, and transition resistance is larger, protection easier misoperation during protection opposite direction outlet earth fault.

Owing to there is very strong zero-sequence mutual inductance between analyses for double circuits on same tower line; existing ground distance protection cannot obtain the zero-sequence current on another loop line road; the impact of zero-sequence mutual inductance between line cannot be eliminated in algorithm model; by the impact of zero-sequence mutual inductance between line; when tradition ground distance protection is applied to analyses for double circuits on same tower, its protection range will expand greatly; at nearly protection seting scope place usually there is steady-state in fault; make easily misoperation to occur during protection external area error; easily cause the large transfer of trend, cause large area blackout and occur.

Summary of the invention

The object of the invention is to the deficiency overcoming prior art existence, a kind of non-same famous prime minister's cross-line ground fault recognition method of double-circuit line based on non-same famous prime minister's cross-line ground actual measurement is provided.The method takes into account the zero sequence compensation electric current on the impact calculating analyses for double circuits on same tower I loop line road of zero-sequence mutual inductance between line, calculate the non-same famous prime minister's cross-line earth fault point voltage of double-circuit line, calculate the zero-sequence current of the non-same famous prime minister's cross-line earth fault of single-ended injection double-circuit line, calculate the faulted phase voltage at protection seting scope place, analyses for double circuits on same tower I loop line road, by judging that protection seting scope place, analyses for double circuits on same tower I loop line road drops on (180 ° to the phase angle of the zero-sequence current of the non-same famous prime minister's cross-line earth fault of the leading single-ended injection double-circuit line of voltage drop of the non-same famous prime minister's cross-line earth fault of double-circuit line, 360 °) whether set up in scope, to determine whether send action trip signal, principle eliminates zero-sequence mutual inductance between line, transition resistance, the factor such as load current and power system operation mode is on the impact of fault distinguishing result, unprotect dead band when the non-same famous prime minister's cross-line earth fault of double-circuit line occurs the outlet of protection positive direction, not misoperation when the non-same famous prime minister's cross-line earth fault of double-circuit line occurs in protection outlet in the other direction, be applicable to the backup protection of analyses for double circuits on same tower single-end electrical quantity.

For completing above-mentioned purpose, the present invention adopts following technical scheme:

Based on the non-same famous prime minister's cross-line ground fault recognition method of double-circuit line of non-same famous prime minister's cross-line ground actual measurement, it is characterized in that, comprise following sequential steps:

(1) protector measuring analyses for double circuits on same tower I returns the faulted phase voltage of route protection installation place faulted phase current and zero-sequence current wherein, φ is fault phase; φ=I loop line road A phase, I loop line road B phase, I loop line road C phase;

(2) protective device calculates the zero sequence compensation electric current on analyses for double circuits on same tower I loop line road

$\mathrm{\Δ}\stackrel{\·}{I}={\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{Z_{I0}-Z_{I1}}{Z_{I1}}{\stackrel{\·}{I}}_{I0}+\frac{Z_m}{3Z_{I1}}{\stackrel{\·}{I}}_{I0}(-\mathrm{ocs}(r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))$

Wherein, $r_1={\sin }^{-1}\left(\frac{a_3{b}_1}{\sqrt{{\left(a_1{b}_1\right)}^2+{\left(a_1{b}_3\right)}^2}}\right);r_2={\sin }^{-1}\left(\frac{a_1{b}_2-a_2{b}_1}{\sqrt{{\left(a_3{b}_1\right)}^2+{\left(a_1{b}_3\right)}^2}}\right);a_1=\mathrm{Re}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}}{Z_{I1}}\right);b_1=\mathrm{Im}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}}{Z_{I1}}\right);$

$a_2=\mathrm{Re}({\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{Z_{I0}-Z_{I1}}{Z_{I1}}{\stackrel{\·}{I}}_{I0});b_2=\mathrm{Im}({\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{Z_{I0}-Z_{I1}}{Z_{I1}}{\stackrel{\·}{I}}_{I0});a_3=b_3=\left|\frac{Z_m}{3Z_{I1}}{\stackrel{\·}{I}}_{I0}\right|;\mathrm{\β}=\mathrm{Arg}\left(\frac{Z_m}{3Z_{I1}}{\stackrel{\·}{I}}_{I0}\right);$ Z _mfor the zero-sequence mutual inductance between analyses for double circuits on same tower I loop line road and analyses for double circuits on same tower II loop line road; Z _i0for the zero sequence impedance on analyses for double circuits on same tower I loop line road; Z _i1for the positive sequence impedance on analyses for double circuits on same tower I loop line road; φ=I loop line road A phase, I loop line road B phase, I loop line road C phase; for real part; for imaginary part; for real part; for imaginary part; for amplitude; for phase angle; for arcsin function value; for arcsin function value; J is complex operator;

(3) protective device calculates the non-same famous prime minister's cross-line earth fault point voltage of double-circuit line

${\stackrel{\·}{U}}_f={\stackrel{\·}{U}}_{\mathrm{I\φ}}-\frac{\mathrm{Im}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}}{{\stackrel{\·}{I}}_{I0}+{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))}\right)}{\mathrm{Im}\left(\frac{Z_{I1}\mathrm{\Δ}\stackrel{\·}{I}}{{\stackrel{\·}{I}}_{I0}+{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))}\right)}{Z}_{I1}\mathrm{\Δ}\stackrel{\·}{I}$

Wherein, for imaginary part; Z _i1for the positive sequence impedance on analyses for double circuits on same tower I loop line road; φ=I loop line road A phase, I loop line road B phase, I loop line road C phase;

for imaginary part; for the zero sequence compensation electric current on analyses for double circuits on same tower I loop line road;

(4) protective device calculates the zero-sequence current of the non-same famous prime minister's cross-line earth fault of single-ended injection double-circuit line

${\stackrel{\·}{I}}_{f0}={\stackrel{\·}{I}}_{I0}+{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))$

(5) protective device calculates analyses for double circuits on same tower I loop line road protection seting scope place l _setfaulted phase voltage

$\stackrel{\·}{U}\left(l_{\mathrm{set}}\right)={\stackrel{\·}{U}}_{\mathrm{I\φ}}-Z_{I1}\mathrm{\Δ}\stackrel{\·}{I}\frac{l_{\mathrm{set}}}{l}$

Wherein, l is that analyses for double circuits on same tower I returns line length; Z _i1for the positive sequence impedance on analyses for double circuits on same tower I loop line road; for the zero sequence compensation electric current on analyses for double circuits on same tower I loop line road; l _setfor analyses for double circuits on same tower I loop line road protection seting scope, get 0.85 times of analyses for double circuits on same tower I and return line length;

(6) protective device judges drop in (180 °, 360 °) scope and whether set up, if set up, then judge that the non-same famous prime minister's cross-line earth fault of double-circuit line is positioned within the protection seting scope of analyses for double circuits on same tower I loop line road, send action trip signal; Otherwise, if drop within (0 °, 180 °) scope, then send block signal.

Feature of the present invention and technological achievement:

The inventive method only uses single-ended single back line electric parameters, does not need to introduce another loop line road electric parameters, differentiates result not by the impact of power system operation mode, still has very high fault distinguishing accuracy when larger change occurs power system operation mode.The inventive method only uses single-ended single back line electric parameters, does not need to introduce another loop line road electric parameters, and Protection secondary circuit is separate does not go here and there mutually, strengthens fault distinguishing result accuracy.The inventive method is by judging that protection seting scope place, analyses for double circuits on same tower I loop line road drops on (180 ° to the phase angle of the zero-sequence current of the non-same famous prime minister's cross-line earth fault of the leading single-ended injection double-circuit line of voltage drop of the non-same famous prime minister's cross-line earth fault of double-circuit line, 360 °) whether set up in scope, to determine whether send action trip signal, principle eliminates zero-sequence mutual inductance between line, transition resistance, the factor such as load current and power system operation mode is on the impact of fault distinguishing result, unprotect dead band when the non-same famous prime minister's cross-line earth fault of double-circuit line occurs the outlet of protection positive direction, not misoperation when the non-same famous prime minister's cross-line earth fault of double-circuit line occurs in protection outlet in the other direction, be applicable to the backup protection of analyses for double circuits on same tower single-end electrical quantity.

Accompanying drawing explanation

Fig. 1 is application analyses for double circuits on same tower transmission system schematic diagram of the present invention.

Embodiment

Fig. 1 is application analyses for double circuits on same tower transmission system schematic diagram of the present invention.In Fig. 1, PT is voltage transformer, and CT is current transformer, and m, n are the two ends bus numbering of analyses for double circuits on same tower.Protector measuring analyses for double circuits on same tower I returns the faulted phase voltage of route protection installation place faulted phase current and zero-sequence current wherein, φ is fault phase; φ=I loop line road A phase, I loop line road B phase, I loop line road C phase.

Protective device calculates the zero sequence compensation electric current on analyses for double circuits on same tower I loop line road

$\mathrm{\Δ}\stackrel{\·}{I}={\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{Z_{I0}-Z_{I1}}{Z_{I1}}{\stackrel{\·}{I}}_{I0}+\frac{Z_m}{3Z_{I1}}{\stackrel{\·}{I}}_{I0}(-\mathrm{ocs}(r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))$

Wherein, $r_1={\sin }^{-1}\left(\frac{a_3{b}_1}{\sqrt{{\left(a_1{b}_1\right)}^2+{\left(a_1{b}_3\right)}^2}}\right);r_2={\sin }^{-1}\left(\frac{a_1{b}_2-a_2{b}_1}{\sqrt{{\left(a_3{b}_1\right)}^2+{\left(a_1{b}_3\right)}^2}}\right);a_1=\mathrm{Re}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}}{Z_{I1}}\right);b_1=\mathrm{Im}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}}{Z_{I1}}\right);$

$a_2=\mathrm{Re}({\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{Z_{I0}-Z_{I1}}{Z_{I1}}{\stackrel{\·}{I}}_{I0});b_2=\mathrm{Im}({\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{Z_{I0}-Z_{I1}}{Z_{I1}}{\stackrel{\·}{I}}_{I0});a_3=b_3=\left|\frac{Z_m}{3Z_{I1}}{\stackrel{\·}{I}}_{I0}\right|;\mathrm{\β}=\mathrm{Arg}\left(\frac{Z_m}{3Z_{I1}}{\stackrel{\·}{I}}_{I0}\right);$ Z _mfor the zero-sequence mutual inductance between analyses for double circuits on same tower I loop line road and analyses for double circuits on same tower II loop line road; Z _i0for the zero sequence impedance on analyses for double circuits on same tower I loop line road; Z _i1for the positive sequence impedance on analyses for double circuits on same tower I loop line road; φ=I loop line road A phase, I loop line road B phase, I loop line road C phase; for real part; for imaginary part; for real part; for imaginary part; for amplitude; for phase angle; for arcsin function value; for arcsin function value; J is complex operator; r ₁, r ₂for intermediate variable, without actual physics meaning.

Protective device calculates the non-same famous prime minister's cross-line earth fault point voltage of double-circuit line

${\stackrel{\·}{U}}_f={\stackrel{\·}{U}}_{\mathrm{I\φ}}-\frac{\mathrm{Im}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}}{{\stackrel{\·}{I}}_{I0}+{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))}\right)}{\mathrm{Im}\left(\frac{Z_{I1}\mathrm{\Δ}\stackrel{\·}{I}}{{\stackrel{\·}{I}}_{I0}+{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))}\right)}{Z}_{I1}\mathrm{\Δ}\stackrel{\·}{I}$

Wherein, for imaginary part; Z _i1for the positive sequence impedance on analyses for double circuits on same tower I loop line road; φ=I loop line road A phase, I loop line road B phase, I loop line road C phase;

for imaginary part; for the zero sequence compensation electric current on analyses for double circuits on same tower I loop line road.

Protective device calculates the zero-sequence current of the non-same famous prime minister's cross-line earth fault of single-ended injection double-circuit line

${\stackrel{\·}{I}}_{f0}={\stackrel{\·}{I}}_{I0}+{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))$

Protective device calculates analyses for double circuits on same tower I loop line road protection seting scope place l _setfaulted phase voltage

$\stackrel{\·}{U}\left(l_{\mathrm{set}}\right)={\stackrel{\·}{U}}_{\mathrm{I\φ}}-Z_{I1}\mathrm{\Δ}\stackrel{\·}{I}\frac{l_{\mathrm{set}}}{l}$

Wherein, l is that analyses for double circuits on same tower I returns line length; Z _i1for the positive sequence impedance on analyses for double circuits on same tower I loop line road; for the zero sequence compensation electric current on analyses for double circuits on same tower I loop line road; l _setfor analyses for double circuits on same tower I loop line road protection seting scope, get 0.85 times of analyses for double circuits on same tower I and return line length.

If the non-same famous prime minister's cross-line earth fault of double-circuit line is positioned within the protection seting scope of analyses for double circuits on same tower I loop line road, then protection seting scope place in analyses for double circuits on same tower I loop line road is to the phase angle of the zero-sequence current of the non-same famous prime minister's cross-line earth fault of the leading single-ended injection double-circuit line of voltage drop of the non-same famous prime minister's cross-line earth fault of double-circuit line drop in (180 ° 360 °) scope.

If the non-same famous prime minister's cross-line earth fault of double-circuit line is positioned at outside the protection seting scope of analyses for double circuits on same tower I loop line road, then protection seting scope place in analyses for double circuits on same tower I loop line road is to the phase angle of the zero-sequence current of the non-same famous prime minister's cross-line earth fault of the leading single-ended injection double-circuit line of voltage drop of the non-same famous prime minister's cross-line earth fault of double-circuit line drop within (0 ° 180 °) scope.This phase characteristic is utilized to propose the non-same famous prime minister's cross-line earth fault identical criterion of double-circuit line as follows:

Protective device judges drop in (180 ° 360 °) scope and whether set up, if set up, then judge that the non-same famous prime minister's cross-line earth fault of double-circuit line is positioned within the protection seting scope of analyses for double circuits on same tower I loop line road, send action trip signal; Otherwise, if drop within (0 °, 180 °) scope, then send block signal.

The inventive method only uses single-ended single back line electric parameters, does not need to introduce another loop line road electric parameters, differentiates result not by the impact of power system operation mode, still has very high fault distinguishing accuracy when larger change occurs power system operation mode.The inventive method only uses single-ended single back line electric parameters, does not need to introduce another loop line road electric parameters, and Protection secondary circuit is separate does not go here and there mutually, strengthens fault distinguishing result accuracy.The inventive method is by judging that protection seting scope place, analyses for double circuits on same tower I loop line road drops on (180 ° to the phase angle of the zero-sequence current of the non-same famous prime minister's cross-line earth fault of the leading single-ended injection double-circuit line of voltage drop of the non-same famous prime minister's cross-line earth fault of double-circuit line, 360 °) whether set up in scope, to determine whether send action trip signal, principle eliminates zero-sequence mutual inductance between line, transition resistance, the factor such as load current and power system operation mode is on the impact of fault distinguishing result, unprotect dead band when the non-same famous prime minister's cross-line earth fault of double-circuit line occurs the outlet of protection positive direction, not misoperation when the non-same famous prime minister's cross-line earth fault of double-circuit line occurs in protection outlet in the other direction, be applicable to the backup protection of analyses for double circuits on same tower single-end electrical quantity.

The foregoing is only preferred embodiment of the present invention; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses, the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.

Claims (1)

1., based on the non-same famous prime minister's cross-line ground fault recognition method of double-circuit line of non-same famous prime minister's cross-line ground actual measurement, it is characterized in that, comprise following sequential steps:

(1) protective device protector measuring analyses for double circuits on same tower I returns the faulted phase voltage of route protection installation place faulted phase current and zero-sequence current wherein, φ is fault phase; φ=I loop line road A phase, I loop line road B phase, I loop line road C phase.

(2) protective device protective device calculates the zero sequence compensation electric current on analyses for double circuits on same tower I loop line road

$\mathrm{\Δ}\stackrel{\·}{I}={\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{Z_{I0}-Z_{I1}}{Z_{I1}}{\stackrel{\·}{I}}_{I0}+\frac{Z_m}{3Z_{I1}}{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))$

Wherein, $r_1={\sin }^{-1}\left(\frac{a_3{b}_1}{\sqrt{{\left(a_3{b}_1\right)}^2+{\left(a_1{b}_3\right)}^2}}\right);r_2={\sin }^{-1}\left(\frac{a_1{b}_2-a_2{b}_1}{\sqrt{{\left(a_3{b}_1\right)}^2+{\left(a_1{b}_3\right)}^2}}\right);a_1=\mathrm{Re}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}}{Z_{I1}}\right);b_1=\mathrm{Im}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}}{Z_{I1}}\right);$ $a_2=\mathrm{Re}({\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{Z_{I0}-Z_{I1}}{Z_{I1}}{\stackrel{\·}{I}}_{I0});b_2=\mathrm{Im}({\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{Z_{I0}-Z_{I1}}{Z_{I1}}{\stackrel{\·}{I}}_{I0});a_3=b_3=\left|\frac{Z_m}{3Z_{I1}}\stackrel{\·}{I}{I0}_{}\right|;\mathrm{\β}=\mathrm{Arg}\left(\frac{Z_m}{3Z_{I1}}{\stackrel{\·}{I}}_{I0}\right);$ Z _mfor the zero-sequence mutual inductance between analyses for double circuits on same tower I loop line road and analyses for double circuits on same tower II loop line road; Z _i0for the zero sequence impedance on analyses for double circuits on same tower I loop line road; Z _i1for the positive sequence impedance on analyses for double circuits on same tower I loop line road; φ=I loop line road A phase, I loop line road B phase, I loop line road C phase; for real part; for imaginary part; for real part; for imaginary part; for amplitude; for phase angle; for arcsin function value; for arcsin function value; J is complex operator.

(3) protective device protective device calculates the non-same famous prime minister's cross-line earth fault point voltage of double-circuit line

${\stackrel{\·}{U}}_f={\stackrel{\·}{U}}_{\mathrm{I\φ}}-\frac{\mathrm{Im}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}}{{\stackrel{\·}{I}}_{I0}+{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))}\right)}{\mathrm{Im}\left(\frac{Z_{I1}\mathrm{\Δ}\stackrel{\·}{I}}{{\stackrel{\·}{I}}_{I0}+{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))}\right)}{Z}_{I1}\mathrm{\Δ}\stackrel{\·}{I}$

Wherein, for imaginary part; Z _i1for the positive sequence impedance on analyses for double circuits on same tower I loop line road; φ=I loop line road A phase, I loop line road B phase, I loop line road C phase; for imaginary part; for the zero sequence compensation electric current on analyses for double circuits on same tower I loop line road;

(4) protective device calculates the zero-sequence current of the non-same famous prime minister's cross-line earth fault of single-ended injection double-circuit line

${\stackrel{\·}{I}}_{f0}={\stackrel{\·}{I}}_{I0}+{\stackrel{\·}{I}}_{I0}(-\cos (r_1+r_2-\mathrm{\β})-j\sin (r_1+r_2-\mathrm{\β}))$

(5) protective device calculates analyses for double circuits on same tower I loop line road protection seting scope place l _setfaulted phase voltage

$\stackrel{\·}{U}\left(l_{\mathrm{set}}\right)={\stackrel{\·}{U}}_{\mathrm{I\φ}}-Z_{I1}\mathrm{\Δ}\stackrel{\·}{I}\frac{l_{\mathrm{set}}}{l}$

Wherein, l is that analyses for double circuits on same tower I returns line length; Z _i1for the positive sequence impedance on analyses for double circuits on same tower I loop line road; for the zero sequence compensation electric current on analyses for double circuits on same tower I loop line road; l _setfor analyses for double circuits on same tower I loop line road protection seting scope, get 0.85 times of analyses for double circuits on same tower I and return line length;

(6) protective device judges drop in (180 °, 360 °) scope and whether set up, if set up, then judge that the non-same famous prime minister's cross-line earth fault of double-circuit line is positioned within the protection seting scope of analyses for double circuits on same tower I loop line road, send action trip signal; Otherwise, if drop within (0 °, 180 °) scope, then send block signal.