CN104201660A - Triangular looped network transient state unit protecting method based on direction traveling wave integral comparison principles - Google Patents

Abstract

The invention relates to a triangular looped network transient state unit protecting method based on direction traveling wave integral comparison principles and belongs to the technical field of power system relay protection. The method includes: the direction pilot protection of each circuit of a triangular looped network is regarded as a to-be-protected unit; after a fault occurs, the direction element at the circuit measuring end in a fixed time window is used to obtain the amplitude integral ratio lambda of forward traveling waves to reverse traveling waves so as to judge fault direction; if the ratio is smaller or equal to a set threshold lambda sigma set, the fault is judged as the forward fault, and if the ratio is larger than the set threshold lambda sigma set, and the fault is judged as the reverse fault. When the direction elements at two ends of a branch are judged as forward faults, the fault is located on the branch, and the fault occurs inside the protecting area of the triangular looped network; or else the fault occurs outside the triangular looped network. A large amount of simulation experiments indicate that the method is good in effect.

Description

A kind of triangle looped network transient cell protection method based on direction row ripple integral contrast principle

Technical field

The present invention relates to a kind of triangle looped network transient cell protection method based on direction row ripple integral contrast principle, belong to Relay Protection Technology in Power System field.

Background technology

Along with the continuous construction of superhigh pressure and UHV transmission line; putting into operation successively of large capacity unit; electrical network interconnected; these are all had higher requirement to relay protection of power system; after line fault, quickly and reliably removing fault is the effective measures that strengthen circuit ability to transmit electricity and improve Power Network Transient Stability.And traditional relaying protection based on power frequency amount shown gradually can not the out of order weak tendency of fast detecting.The row ripple that utilizes fault transient to produce that starts from the seventies in last century carrys out the traveling-wave protection of detection failure, compared with power frequency amount route protection based on power frequency amount, because its fault detect speed being exceedingly fast enjoys people to pay close attention to.

Due to the special construction of triangle looped network; fault initial row ripple can be transmitted to measuring end by the loop that perfects circuit formation; the pilot protection that traditional use current break direction is formed is no longer applicable, can fine addressing the above problem and form a cell protection by the directional pilot protection of triangle looped network three-line.

Summary of the invention

The technical problem to be solved in the present invention is based on row wave amplitude comparison expression direction protection; that utilizes direct wave and returning wave amplitude recently forms criterion; a kind of triangle looped network transient cell protection method based on direction row ripple integral contrast principle is proposed; overcome traditional power frequency amount protection and be subject to line distribution capacitance, the shortcoming of current transformer effect of saturation degree.

Technical scheme of the present invention is: a kind of triangle looped network transient cell protection method based on direction row ripple integral contrast principle, and the directional pilot protection of every circuit of triangle looped network is set to a protected location; After fault occurs, utilize the direct wave of the direction component acquisition of the interior circuit measuring end of timing window admittedly and the ratio λ of returning wave amplitude integration to carry out failure judgement direction; If ratio λ is less than or equal to the threshold value λ adjusting _{∑ set}, be judged to positive direction fault, if ratio λ is greater than threshold value λ _{∑ set}, be judged to reverse direction failure; In the time that a branch road direction of both ends element is all judged to be positive direction fault, be judged to fault and be positioned at this branch road, judge that triangle looped network protection intra-zone breaks down; Otherwise, be judged to be triangle looped network outside and break down.

Concrete steps are:

The sample rate of A, row ripple transient signal is set to 20kHz, definition t ₀headed by wave head arrive moment of measuring end, l _minfor measuring end the shortest perfect outlet; In triangle loop grid, define three ends and be respectively M end, N end and Q end, the directional relay at M, N two ends is respectively R ₁, R ₂; The directional relay at N, Q two ends is respectively R ₃, R ₄; The directional relay at Q, M two ends is respectively R ₅, R ₆; At [t ₀, t ₀+ 2l _min/ v] in the time, in the time that fault occurs, each extreme direction relay R in triangle looped network ₁～R ₆obtain respectively measuring end forward and the returning wave absolute value of discretization according to formula (1) and formula (2):

u ⁺＝(u(k)+Z _Ci(k))/2 (1)

u ^-＝(u(k)-Z _Ci(k))/2 (2)

Directional relay R ₁～R ₆obtain respectively measuring end forward and the returning wave amplitude integrated value of discretization according to formula (3) and formula (4):

$S^{+}=\mathrm{\Δt}\underset{k=0}{\overset{m}{\mathrm{\Σ}}}|u\left(k\right)+Z_{c}i\left(k\right)|/2---\left(3\right)$

$S^{-}=\mathrm{\Δt}\underset{k=0}{\overset{m}{\mathrm{\Σ}}}|u\left(k\right)+Z_{c}i\left(k\right)|/2---\left(4\right)$

In formula, be surge impedance of a line, L and C are inductance and the electric capacity of unit length circuit, and Δ t is the sampling interval, and m is the long 2l of being of window _minthe sampling number of/v, k represents sampled point, t ₀shi Keji k=0;

B, the direct wave amplitude integration and the S that utilize formula (1) and formula (2) to calculate ⁺, returning wave amplitude integration and S-calculate its ratio according to formula (3):

λ _∑＝S ⁺/S ^- (5)

C, by λ _∑with the threshold value λ setting _{∑ set}compare, if λ _∑≤ λ _{∑ set}, be judged to be positive direction fault; If λ _∑> λ _{∑ set}, be judged to be reverse direction failure; Due to total existence: when positive direction fault, λ _∑<1; When reverse direction failure, λ _∑>=1, be greater than 1 value as threshold value therefore can select.For ensureing reliability and sensitivity, through a large amount of emulation of PSCAD/EMTDC, get threshold value and be taken as 1.2.

D, just can determine fault branch in conjunction with the differentiation result of circuit direction of both ends relay in triangle looped network, that is:

If ${\mathrm{\&lambda;}}_{R_1\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_1\mathrm{\&Sigma;set}}$ And ${\mathrm{\&lambda;}}_{R_2\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_2\mathrm{\&Sigma;set}},$ Fault is positioned at MN branch road;

If ${\mathrm{\&lambda;}}_{R_3\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_3\mathrm{\&Sigma;set}}$ And ${\mathrm{\&lambda;}}_{R_4\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_4\mathrm{\&Sigma;set}},$ Fault is positioned at NQ branch road;

If ${\mathrm{\&lambda;}}_{R_5\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_5\mathrm{\&Sigma;set}}$ And ${\mathrm{\&lambda;}}_{R_6\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_6\mathrm{\&Sigma;set}},$ Fault is positioned at QM branch road;

If above-mentioned three formulas all do not meet, judge that triangle loop grid outside breaks down.

The invention has the beneficial effects as follows:

(1) this method is expert on wave amplitude comparison expression protection basis and is utilized integration to build criterion; higher than row wave amplitude comparison expression direction protection reliability; and contrast and traditional power frequency amount protection; overcome traditional power frequency amount protection and be subject to line distribution capacitance, the shortcoming of current transformer effect of saturation degree.

(2) directional pilot protection of this method by triangle looped network three-line forms a cell protection, overcome the shortcoming that pilot protection that traditional use current break direction forms cannot diabolo looped network correct operation.

Brief description of the drawings

Fig. 1 is the simulated line illustraton of model of triangle ring-main unit protection;

Fig. 2 is F ₃m end protection R when point failure ₁direct wave absolute value and returning wave absolute value;

Fig. 3 is F ₃n end protection R when point failure ₂direct wave absolute value and returning wave absolute value;

Fig. 4 is F ₃n end protection R when point failure ₃direct wave absolute value and returning wave absolute value;

Fig. 5 is F ₃q end protection R when point failure ₄direct wave absolute value and returning wave absolute value;

Fig. 6 is F ₃q end protection R when point failure ₅direct wave absolute value and returning wave absolute value;

Fig. 7 is F ₃m end protection R when point failure ₆direct wave absolute value and returning wave absolute value.

Fig. 8 is F ₁m end protection R when point failure ₁direct wave absolute value and returning wave absolute value;

Fig. 9 is F ₁n end protection R when point failure ₂direct wave absolute value and returning wave absolute value;

Figure 10 is F ₁n end protection R when point failure ₃direct wave absolute value and returning wave absolute value;

Figure 11 is F ₁q end protection R when point failure ₄direct wave absolute value and returning wave absolute value;

Figure 12 is F ₁q end protection R when point failure ₅direct wave absolute value and returning wave absolute value;

Figure 13 is F ₁m end protection R when point failure ₆direct wave absolute value and returning wave absolute value;

Figure 14 is F ₄m end protection R when point failure ₁direct wave absolute value and returning wave absolute value;

Figure 15 is F ₄n end protection R when point failure ₂direct wave absolute value and returning wave absolute value;

Figure 16 is F ₄n end protection R when point failure ₃direct wave absolute value and returning wave absolute value;

Figure 17 is F ₄q end protection R when point failure ₄direct wave absolute value and returning wave absolute value;

Figure 18 is F ₄q end protection R when point failure ₅direct wave absolute value and returning wave absolute value;

Figure 19 is F ₄m end protection R when point failure ₆direct wave absolute value and returning wave absolute value.

Embodiment

Below in conjunction with the drawings and specific embodiments, the invention will be further described.

Embodiment 1: embodiment 1: in the analogue system shown in Fig. 1, PM, MN, NQ and tetra-sections of line lengths of QM are respectively 100km, 100km, 70km and 80km.The electric current positive direction that specifies each protection is bus sensing circuit.Assumed fault is positioned at MQ branch road, and apart from M end 20km, transition resistance is 10 Ω.

The sample rate of A, row ripple transient signal is set to 20kHz.Definition t ₀headed by wave head arrive moment of measuring end, l _minfor measuring end the shortest perfect outlet.In triangle loop grid, define three ends and be respectively M end, N end and Q end, the directional relay at M, N two ends is respectively R ₁, R ₂; The directional relay at N, Q two ends is respectively R ₃, R ₄; The directional relay at Q, M two ends is respectively R ₅, R ₆.At [t ₀, t ₀+ 2l _min/ v] in the time, in the time that fault occurs, each extreme direction relay R in triangle looped network ₁～R ₆obtain respectively measuring end forward and the returning wave absolute value of discretization according to formula (1) and formula (2), as Fig. 2～Fig. 7.

u ⁺＝(u(k)+Z _Ci(k))/2 (1)

u ^-＝(u(k)-Z _Ci(k))/2 (2)

Directional relay R ₁～R ₆obtain measuring end forward and the returning wave amplitude integrated value of discretization according to formula (3) and formula (4),

$S^{+}=\mathrm{\&Delta;t}\underset{k=0}{\overset{m}{\mathrm{\&Sigma;}}}|u\left(k\right)+Z_{c}i\left(k\right)|/2---\left(3\right)$

$S^{-}=\mathrm{\&Delta;t}\underset{k=0}{\overset{m}{\mathrm{\&Sigma;}}}|u\left(k\right)+Z_{c}i\left(k\right)|/2---\left(4\right)$

In formula, be surge impedance of a line, L and C are inductance and the electric capacity of unit length circuit, Z _c=239.38 Ω; Δ t is the sampling interval; M is the long 2l of being of window _minthe sampling number of/v, m=20; K represents sampled point, t ₀shi Keji k=0.

Result of calculation is: $S_{R_1}^{+}=0.3639,S_{R_1}^{-}0.1645;S_{R_2}^{+}=0.1638,S_{R_2}^{-}=0.3486;S_{R_3}^{+}=0.0255,S_{R_3}^{-}=0.1892;$

$S_{R_4}^{+}=0.1878,S_{R_4}^{-}=0.0266;S_{R5}^{+}=0.3598,S_{R5}^{-}0.5626;S_{R_6}^{+}=0.3550,S_{R_6}^{-}=0.7007.$

B, the direct wave amplitude integration and the S that utilize formula (3) and formula (4) to calculate ⁺, returning wave amplitude integration and S ^-calculate its ratio according to formula (5), then by itself and threshold value λ _{∑ set}=1.2 compare,

λ _∑＝S ⁺/S ^- (5)

Result of calculation is, ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_1}=2.2122,$ Meet λ _∑> λ _{∑ set}, ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_1}=2.2122,$ Meet λ _∑≤ λ _{∑ set}; ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_3}=0.1350,$ Meet λ _Σ≤ λ _{Σ set} ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_4}=7.0695,$ Meet λ _∑> λ _{∑ set}; ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_5}=0.6380,{\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_6}=0.5066,$ Meet λ _∑≤ λ _{∑ set}.So we obtain R ₅, R ₆positive direction fault all occurs, and it is upper that fault occurs in circuit MQ, is troubles inside the sample space, verified this triangle looped network transient cell protection correct judgment.

Embodiment 2: in the analogue system shown in Fig. 1, assumed fault is positioned at MN branch road, apart from M end 10km, transition resistance is 10 Ω, sample frequency is 20kHz.

Press the method for embodiment 1 and calculate each extreme direction relay R in triangle looped network ₁～R ₆the absolute value of direct wave and the absolute value of returning wave, its result is Fig. 8～Figure 13.Calculated direction relay R again ₁～R ₆measuring end forward and the returning wave amplitude integrated value of place's discretization, then calculate each extreme direction relay R in triangle looped network ₁～R ₆λ _∑value.

Result of calculation is, ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_1}=0.5263,{\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_2}=0.5992,$ Meet λ _∑≤ λ _{∑ set}; ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_3}=1.3011,$ Meet λ _∑> λ _{∑ set}, ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_4}=0.7865,$ Meet λ _∑≤ λ _{∑ set}; ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_1}=2.2122,$ Meet λ _∑≤ λ _{∑ set}, ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_6}=1.7794,$ Meet λ _∑> λ _{∑ set}.So we obtain R ₁, R ₂positive direction fault all occurs, and it is upper that fault occurs in circuit MN, is troubles inside the sample space, verified this triangle looped network transient cell protection correct judgment.

Embodiment 3: in the analogue system shown in Fig. 1, assumed fault is positioned at circuit PM, apart from M end 50km, transition resistance is 10 Ω, sample frequency is 20kHz.

Press the method for embodiment 1 and calculate each extreme direction relay R in triangle looped network ₁～R ₆the absolute value of direct wave and the absolute value of returning wave, its result is Figure 14～Figure 19.Calculated direction relay R again ₁～R ₆measuring end forward and the returning wave amplitude integrated value of place's discretization, then calculate each extreme direction relay R in triangle looped network ₁～R ₆λ _∑value.

Result of calculation is, ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_1}=2.2122,$ Meet λ _∑> λ _{∑ set}, ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_2}=0.5685,$ Meet λ _∑≤ λ _{∑ set}; ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_3}=0.6690,$ Meet _λ∑≤λ _{∑ set}, ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_4}=1.4361,$ Meet λ _∑> λ _{∑ set}; ${\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_5}=0.5800,{\mathrm{\&lambda;}}_{\mathrm{\&Sigma;}{R}_6}=1.6818,$ Meet λ _∑> λ _{∑ set}.Occur in outside district so obtain fault, verified this triangle looped network transient cell protection correct judgment.

By reference to the accompanying drawings the specific embodiment of the present invention is explained in detail above, but the present invention is not limited to above-mentioned execution mode, in the ken possessing those of ordinary skill in the art, can also under the prerequisite that does not depart from aim of the present invention, make various variations.

Claims (2)

1. the triangle looped network transient cell protection method based on direction row ripple integral contrast principle, is characterized in that: the directional pilot protection of every circuit of triangle looped network is set to a protected location; After fault occurs, utilize the direct wave of the direction component acquisition of the interior circuit measuring end of timing window admittedly and the ratio λ of returning wave amplitude integration to carry out failure judgement direction; If ratio λ is less than or equal to the threshold value λ adjusting _{∑ set}, be judged to positive direction fault, if ratio λ is greater than threshold value λ _{∑ set}, be judged to reverse direction failure; In the time that a branch road direction of both ends element is all judged to be positive direction fault, be judged to fault and be positioned at this branch road, judge that triangle looped network protection intra-zone breaks down; Otherwise, be judged to be triangle looped network outside and break down.

2. the triangle looped network transient cell protection method based on direction row ripple integral contrast principle according to claim 1, is characterized in that concrete steps are:

The sample rate of A, row ripple transient signal is set to 20kHz, definition t ₀headed by wave head arrive moment of measuring end, l _minfor measuring end the shortest perfect outlet; In triangle loop grid, define three ends and be respectively M end, N end and Q end, the directional relay at M, N two ends is respectively R ₁, R ₂; The directional relay at N, Q two ends is respectively R ₃, R ₄; The directional relay at Q, M two ends is respectively R ₅, R ₆; At [t ₀, t ₀+ 2l _min/ v] in the time, in the time that fault occurs, each extreme direction relay R in triangle looped network ₁～R ₆obtain respectively measuring end forward and the returning wave absolute value of discretization according to formula (1) and formula (2):

u ⁺＝(u(k)+Z _Ci(k))/2 (1)

u ^-＝(u(k)-Z _Ci(k))/2 (2)

Directional relay R ₁～R ₆obtain respectively measuring end forward and the returning wave amplitude integrated value of discretization according to formula (3) and formula (4):

$S^{+}=\mathrm{\&Delta;t}\underset{k=0}{\overset{m}{\mathrm{\&Sigma;}}}|u\left(k\right)+Z_{c}i\left(k\right)|/2---\left(3\right)$

$S^{-}=\mathrm{\&Delta;t}\underset{k=0}{\overset{m}{\mathrm{\&Sigma;}}}|u\left(k\right)+Z_{c}i\left(k\right)|/2---\left(4\right)$

In formula, be surge impedance of a line, L and C are inductance and the electric capacity of unit length circuit, and Δ t is the sampling interval, and m is the long 2l of being of window _minthe sampling number of/v, k represents sampled point, t ₀shi Keji k=0;

B, the direct wave amplitude integration and the S that utilize formula (1) and formula (2) to calculate ⁺, returning wave amplitude integration and S ^-calculate its ratio according to formula (3):

λ _∑＝S ⁺/S ^- (5)

C, by λ _∑with the threshold value λ setting _{∑ set}compare, if λ _∑≤ λ _{∑ set}, be judged to be positive direction fault; If λ _∑> λ _{∑ set}, be judged to be reverse direction failure, λ _{∑ set}value be taken as 1.2;

D, just can determine fault branch in conjunction with the differentiation result of circuit direction of both ends relay in triangle looped network, that is:

If ${\mathrm{\&lambda;}}_{R_1\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_1\mathrm{\&Sigma;set}}$ And ${\mathrm{\&lambda;}}_{R_2\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_2\mathrm{\&Sigma;set}},$ Fault is positioned at MN branch road;

If ${\mathrm{\&lambda;}}_{R_3\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_3\mathrm{\&Sigma;set}}$ And ${\mathrm{\&lambda;}}_{R_4\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_4\mathrm{\&Sigma;set}},$ Fault is positioned at NQ branch road;

If ${\mathrm{\&lambda;}}_{R_5\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_5\mathrm{\&Sigma;set}}$ And ${\mathrm{\&lambda;}}_{R_6\mathrm{\&Sigma;}}<{\mathrm{\&lambda;}}_{R_6\mathrm{\&Sigma;set}},$ Fault is positioned at QM branch road;

If above-mentioned three formulas all do not meet, judge that triangle loop grid outside breaks down.