CN100365898C - Anti-current mutual inductor saturated conventional difference current trajectory scanning and discrimination method - Google Patents

Abstract

The present invention belongs to the field of relay protection of a power system, which relates to high voltage and ultrahigh voltage power equipment of the power system, particularly to a distinguishing method for current mutual inductor (TA) saturation in bus protection equipment. The distinguishing method collects an output end current of each current mutual inductor in the high voltage and the ultrahigh voltage power equipment according to each cycle of 24 points, obtains the output end currents, and converts the collected output end currents into the corresponding digital quantity. When a criterion without differential current discontinuous points, a conventional K value criterion and a harmonic brake criterion are simultaneously established in criterions, fault action in an area is protected.

Description

The routine difference trajectory mark scanning method of discrimination that the anti-current instrument transformer is saturated

Technical field

The invention belongs to field of relay protection in power, relate in electric power system high pressure, the ultrahigh voltage power equipment (especially bus protection equipment) and be used for the saturated method of discrimination of current transformer (TA).

Background technology

The effect of relay protection of power system is when the adjacent circuit breaker in energy quick acting tripping fault point when breaking down of certain part in the electric power system, reduces the accident scope, guarantees the safety of electric power system.Relaying protection judges whether electric power system normally is by the various electric currents after electric current, the voltage transformer progress of disease, voltage analysis are drawn.Electric current, voltage transformer are inductive element, and containing more DC quantity and harmonic content in input variable can be saturated when amount is excessive, progress of disease wave distortion; At present, in relay protection of power system, mainly be the diagnostic method of counting at the saturated method of the differentiation current transformer of external area error.Easily judge by accident during the generating region internal fault again after saturated when serious TA takes place external area error.Therefore the diagnostic method of counting can be restricted in the sensitivity requirement.Simultaneously, because the increase of power system capacity, fault is more serious to the damage of equipment, is protection equipment, can disconnect fast when requiring fault, and the operate time of the diagnostic method of counting generally more than 20ms, this also makes the protection rapidity be restricted.

Summary of the invention

The objective of the invention is to overcome the deficiencies in the prior art, the saturated track scanning method of discrimination of current transformer of a kind of high sensitivity, high reliability is provided, the operate time of this method of discrimination is short, and distinguishing speed is very fast.

The objective of the invention is to realize by following measure:

The saturated track scanning method of discrimination of a kind of current transformer, its differentiation process is as follows:

1. by each the branch current instrument transformer output end current in the time interval collection high pressure of setting, the extra-high tension unit, obtain output end current I _1t, I _2tI _Nt, I _{1 (t+1)}, I _{2 (t+1)}I _{N (t+1)}, I _{1 (t+2)}, I _{2 (t+2)}I _{N (t+2)}..., I _{1 (t+m-1)}, I _{2 (t+m-1)}I _{N (t+m-1)}.n be the sequence number of each branch current instrument transformer, m is the sampling number in each cycle.

2. the output end current of gathering is converted to corresponding digital amount i _1t, i _2tI _Nt, i _{1 (t+1)}, i _{2 (t+1)}I _{N (t+1)}, i _{1 (t+2)}, i _{2 (t+2)}I _{N (t+2)}..., i _{1 (t+m-1)}, i _{2 (t+m-1)}I _{N (t+m-1)}

3. with t, t+1, t+2 ... t+m-1 each branch current addition constantly takes absolute value then and obtains conventional differential current of this moment, and each branch current absolute value addition constantly simultaneously obtains this moment conventional brake electric current, and formula is as follows:

T conventional differential current of the moment=| ∑ I _{φ t}|=| i _1t+ i _2t+ ... + i _Nt|

T+1 conventional differential current of the moment=| ∑ I _{φ (t+1)}|=| i _{1 (t+1)}+ i _{2 (t+1)}+ ... + i _{N (t+1)}|

T+2 conventional differential current of the moment=| ∑ I _{φ (t+2)}|=| i _{1 (t+2)}+ i _{2 (t+2)}+ ... + i _{N (t+2)}|

……

T+m-1 conventional differential current of the moment=| ∑ I _{φ (t+m-1)}|=| i _{1 (t+m-1)}+ i _{2 (t+m-1)}+ ... + i _{N (t+m-1)}|

T is conventional brake electric current=∑ constantly | I _{φ t}|=| i _1t|+| i _2t|+... + | i _Nt|

T+1 is conventional brake electric current=∑ constantly | I _{φ (t+1)}|=| i _{1 (g+1)}|+| i _{2 (t+1)}|+... + | i _{N (t+1)}|

T+2 is conventional brake electric current=∑ constantly | I _{φ (t+2)}|=| i _{1 (t+2)}|+| i _{2 (t+2)}|+... + | i _{N (t+2)}|

……

T+m-1 is conventional brake electric current=∑ constantly | I _{φ (t+m-1)}|=| i _{1 (t+m-1)}|+| i _{2 (t+m-1)}|+... + | i _{N (t+m-1)}|

Than conventional brake electric current, gained ratio is conventional K value with conventional differential current, and the conventional K value of each sampling instant is as follows:

T is conventional K value K constantly _{Conventional t}=| ∑ I _{φ t}|/∑ | I _{φ t}|

T+1 is conventional K value K constantly _{Conventional (t+1)}=| ∑ I _{φ (t+1)}|/∑ | I _{φ (t+1)}|

T+2 is conventional K value K constantly _{Conventional (t+2)}=| ∑ I _{φ (t+2)}|/∑ | I _{φ (t+2)}|

……

T+m-1 is conventional K value K constantly _{Conventional (t+m-1)}=| ∑ I _{φ (t+m-1)}|/∑ | I _{φ (t+m-1)}|

Calculate the conventional K value of each sampling instant by following formula, calculate the radix of high K value as next cycle sampled point.High K value equals the conventional K value addition of last each sampled point of cycle divided by the sampling number in this cycle, and computing formula is as follows:

K _High=(K _{Conventional t}+ K _{Conventional (t-1)}+ K _{Conventional (t-2)}+ ... + K _{Conventional (t-m+1)})/m

M is the sampling number in the last cycle of sampling instant t in the formula.

4, with above t, t+1, t+2 ..., t+m-1 constantly each branch current digital quantity sum deduct last cycle moment corresponding promptly (t-T), (t+1-T), (t+2-T) ..., (t+m-1-T) each branch current digital quantity sum constantly, take absolute value then.T is a cycle, i _{N (t-T)}Be i _NtThe value of corresponding last cycle, obtain t, t+1, t+2 ..., t+m-1 each branch current digital quantity difference stream sudden change amount absolute value constantly | ∑ Δ I _{φ t}|, ∑ Δ I _{φ (t+1}|, | ∑ Δ I _{φ (t+2)}| ..., | ∑ Δ I _{φ (t+m-1)}|:

|∑ΔI _φt|＝|(i _1t+i _2t+……+i _nt)-(i _1(t-T)+i _2(t-T)+……+i _n(t-T))|

|∑ΔI _φ(t+1)|＝|(i _1(t+1)+i _2(t+1)+……+i _n(t+1))-(i _1(t+1-T)+i _2(t+1-T)+……+i _n(t+1-T))|

|∑ΔI _φ(t+2)|＝|(i _1(t+2)+i _2(t+2)+……+i _n(t+2))-(i _1(t+2-T)+i _2(t+2-T)+……+i _n(t+2-T))|

……

|∑ΔI _φ(t+m-1)|＝|(i _1(t+m-1)+i _2(t+m-1)+……+i _n(t+m-1))-(i _1(t+m-1-T)+i _2(t+m-1-T)+……+i _n(t+m-1-T))|

Simultaneously, with each branch road t, t+1, t+2 ..., t+m-1 constantly and (t-T), (t+1-T), (t+2-T) ..., (t+m-1-T) difference between current constantly the absolute value addition, obtain each branch road t, t+1, t+2 ..., t+m-1 current digital amount sudden change amount absolute value sum ∑ constantly | Δ I _{φ t}|, ∑ | Δ I _{φ (t+1}|, ∑ | Δ I _{φ (t+2)}| ..., ∑ | Δ I _{φ (t+m-1)}|:

∑|ΔI _φt|＝|i _1t-i _1(t-T)|+|i _2t-i _2(t-T)|+……+|i _nt-i _n(t-T)|

∑|ΔI _φ(t+1)|＝|i _1(t+1)-i _1(t+1-T)|+|i _2(t+1)-i _2(t+1-T)|+……+|i _n(t+1)-i _n(t+1-T)|

∑|ΔI _φ(t+2)|＝|i _1(t+2)-i _1(t+2-T)|+|i _2(t+2)-i _2(t+2-T)|+……+|i _n(t+2)-i _n(t+2-T)|

……

∑|ΔI _φ(t+m-1)|＝|i _1(t+m-1)-i _1(t+m-1-T)|+|i _2(t+m-1)-i _2(t+m-1-T)|+……+|i _n(t+m-1)-i _n(t+m-1-T)|

With t serves as to differentiate starting point constantly, with each branch road t current digital amount difference stream sudden change constantly amount absolute value | and ∑ Δ I _{φ t}| divided by each branch road t current digital amount sudden change constantly amount absolute value sum ∑ | Δ I _{φ t}| obtain each branch road t change coefficient X constantly ₁

X ₁＝|∑ΔI _φt|/∑|ΔI _φt|

Calculate t+1, t+2 by that analogy respectively ... t+k-1 is the change coefficient X of each branch road constantly ₂, X ₃... X _KValue:

X ₂＝|∑ΔI _φ(t+1)|/∑|ΔI _φ(t+1)|

X ₃＝|∑ΔI _φ(t+2)|/∑|ΔI _φ(t+2)|

……

X _k=| ∑ Δ I _{φ (t+k-1)}|/∑ | Δ I _{φ (t+k-1)}|, the span of k is 5～m.

As the amount of sudden change signal enabling, and sudden change amount difference stream forms criterion X ₁+ X ₂＜B (B is a constant, and its span is 0.95～1.15) or the saturated flex point criterion of current transformer X ₂/ X ₁(C is a constant to＜C, its span is 0.45～0.70) wherein there is one can satisfy, then be that the external area error current transformer is saturated, then begin to calculate difference stream discontinuous point, with t and t+1 conventional differential current sum constantly divided by conventional brake electric current sum, gained ratio is t+1 mark K value constantly, and calculates t+2, t+3 successively according to following formula ... each mark K value constantly of t+m-1.Formula is as follows:

K _{Mark (t+1)}=(| ∑ I _{φ t}|+| ∑ I _{φ (t+1)}|)/(∑ | I _{φ t}|+∑ | I _{φ (t+1)}|)

K _{Mark (t+2)}=(| ∑ I _{φ (t+1)}|+| ∑ I _{φ (t+2)}|)/(∑ | I _{φ (t+1)}|+∑ | I _{φ (t+2)}|)

……

K _{Mark (t+m-1)}=(| ∑ I _{φ (t+m-2)}|+| ∑ I _{φ (t+m-1)}|)/(∑ | I _{φ (t+m-2)}|+∑ | I _{φ (t+m-1)}|)

5. above result of calculation is carried out following some differentiation:

1) difference stream discontinuous point is differentiated

Each that calculate in above-mentioned the 4th be the standard K value constantly, if satisfy K _Mark＜A (A is a constant, and its span is 0.2～0.4), then this is a discontinuous point, promptly in the cycle (20ms), as long as a discontinuous point is arranged, then this section is distinguished for interruption is arranged a compute segment, when all mark K values all satisfy K 〉=A, promptly represents breakpoint continuously; Enter the judgement of next compute segment in this way successively, as breakpoint continuously, then this criterion is passed through.

2) t conventional K value constantly is K _{Conventional t}＞B ' (B ' be constant, its span is 0.52～0.72)

Computing formula according to conventional K value in the 3rd calculates each K constantly _ConventionalThe value, as satisfy above condition then this criterion pass through.

3) harmonic braking criterion:

(∑I _φt+∑I _φ(t-5))-0.8(∑I _φ(t-2)+∑I _φ(t-3))]/[(|∑I _φt|+|∑I _φ(t-5)|)+

(| ∑ I _{φ (t-2)}|+| ∑ I _{φ (t-3)}|)]＜C ' (C ' be constant, its span is 0.25～0.40)

As result of calculation satisfy following formula then criterion pass through.

4) high K value is quickened criterion: K _High＞0.95;

6. difference stream discontinuous point criterion in the above criterion, conventional K value criterion, when three criterions of harmonic braking criterion are set up simultaneously, the action of protection zone internal fault, if the establishment of high K value acceleration criterion, can direct action.(concrete action logic figure sees accompanying drawing).

The present invention's advantage compared to existing technology:

1. high sensitivity: after conventional difference trajectory mark scanning method catches external area error TA saturated, the different characteristic of spill current when TA continues saturated and bus generating region internal fault, correct decision evolved fault rapidly, troubles inside the sample space then moves rapidly in outlet, the saturated reliable braking of external area error TA.

2. high reliability: reliably prevent the malfunction problem that DC component may cause in the primary current.And when utilizing integration method to efficiently solve the primary current zero crossing, the problem that the spill current discontinuous point is difficult to differentiate.

3. rapidity: utilize quick harmonic braking principle, and the method for discrimination of recollecting in the method in conjunction with sudden change amount difference flowable state shortens in 3ms the saturated differentiation time, the protective device the fastest 15ms that reaches outlet operate time when external area error changes troubles inside the sample space.

Description of drawings

Fig. 1 is a current transformer track scanning diagnostic method criterion graph of a relation of the present invention

Embodiment

The saturated track scanning method of discrimination of a kind of current transformer, its differentiation process is as follows:

1. by each the branch current instrument transformer output end current in the time interval collection high pressure of setting, the extra-high tension unit, obtain output end current I _1t, I _2tI _Nt, I _{1 (t+1)}, I _{2 (t+1)}I _{N (t+1)}, I _{1 (t+2)}, I _{2 (t+2)}I _{N (t+2)}..., I _{1 (t+m-1)}, I _{2 (t+m-1)}I _{N (t+m-1)}.n be the sequence number of each branch current instrument transformer, m is the sampling number in each cycle.The described time interval equals the time of each cycle divided by sampling number (T/m).T+1 represents to differ 1 sampling time point with sampling starting point t, and t+2 represents to differ 2 sampling time points with the sampling starting point, by that analogy; By that analogy; And I _{1 (t+1)}, I _{2 (t+1)}I _{N (t+1)}, then represent the output end current when each output that records differs 1 time interval constantly with sampling starting point t, I _{1 (t+2)}, I _{2 (t+2)}I _{N (t+2)}, then represent the output end current when each output that records differs 2 time intervals constantly with sampling starting point t, by that analogy, I _{1 (t+m-1)}, I _{2 (t+m-1)}I _{N (t+m-1)}Output end current when each output that expression records differs m-1 the time interval constantly with sampling starting point t.Begin constantly constantly to record m output end current constantly altogether to the sampling finish time (t+ (m-1) at interval) from sampling starting point t, promptly number of samples is m.

How many viewdatas of the sampling number in each cycle are handled with the speed of computer is determined, can be 24 points, also can be greater than 24 points.The accuracy of differentiating when being less than at 24 can be affected.

2. the output end current of gathering is converted to corresponding digital amount i _1t, i _2tI _Nt, i _{1 (t+1)}, i _{2 (t+1)}I _{N (t+1)}, i _{1 (t+2)}, i _{2 (t+2)}I _{N (t+2)}..., i _{1 (t+m-1)}, i _{2 (t+m-1)}I _{N (t+m-1)}

3. with t, t+1, t+2 ... t+m-1 each branch current addition constantly takes absolute value then and obtains conventional differential current, simultaneously each branch current absolute value addition is obtained the conventional brake electric current, and formula is as follows:

T conventional differential current of the moment=| ∑ I _{φ t}|=| i _1t+ i _2t+ ... + i _Nt|

T+1 conventional differential current of the moment=| ∑ I _{φ (t+1)}|=| i _{1 (t+1)}+ i _{2 (t+1)}+ ... + i _{N (t+1)}|

T+2 conventional differential current of the moment=| ∑ I _{φ (t+2)}|=| i _{1 (t+2)}+ i _{2 (t+2)}+ ... + i _{N (t+2)}|

……

T+m-1 conventional differential current of the moment=| ∑ I _{φ (t+m-1)}|=| i _{1 (t+m-1)}+ i _{2 (t+m-1)}+ ... + i _{N (t+m-1)}|

T is conventional brake electric current=∑ constantly | I _{φ t}|=| i _1t|+| i _2t|+... + | i _Nt|

T+1 is conventional brake electric current=∑ constantly | I _{φ (t+1)}|=| i _{1 (t+1)}|+| i _{2 (t+2)}|+... + | i _{N (t+1)}|

T+2 is conventional brake electric current=∑ constantly | I _{φ (t+2)}|=| i _{1 (t+2)}|+| i _{2 (t+2)}|+... + | i _{N (t+2)}|

……

T+m-1 is conventional brake electric current=∑ constantly | I _{φ (t+m-1)}|=| i _{1 (t+m-1)}|+| i _{2 (t+m-1)}|+... + | i _{N (t+m-1)}|

Than conventional brake electric current, gained ratio is conventional K value with conventional differential current, and the conventional K value of each sampling instant is as follows:

T is conventional K value K constantly _{Conventional t}=| ∑ I _{φ t}|/∑ | I _{φ t}|

T+1 is conventional K value K constantly _{Conventional (t+1)}=| ∑ I _{φ (t+1)}|/∑ | I _{φ (t+1)}|

T+2 is conventional K value K constantly _{Conventional (t+2)}=| ∑ I _{φ (t+2)}|/∑ | I _{φ (t+2)}|

……

T+m-1 is conventional K value K constantly _{Conventional (t+m-1)}=| ∑ I _{φ (t+m-1)}|/∑ | I _{φ (t+m-1)}|

Calculate the conventional K value of each sampling instant by following formula, calculate the radix of high K value as next cycle sampled point.High K value equals the conventional K value addition of last each sampled point of cycle divided by the sampling number in this cycle, and computing formula is as follows:

K _High=(K _{Conventional t}+ K _{Conventional (t-1)}+ K _{Conventional (t-2)}+ ... + K _{Conventional (t-m+1)})/m

M is the sampling number in the last cycle of sampling instant t in the formula.

As the high K value K that quickens criterion _HighCalculating, must use the conventional K value of each sampled point in the last cycle adjacent to calculate with sampling instant t, in the present embodiment moment of last each sampled point of cycle is expressed as respectively t-1, t-2 ... t-m+1.

4, with above t, t+1, t+2 ..., t+m-1 constantly each branch current digital quantity sum deduct last cycle moment corresponding promptly (t-T), (t+1-T), (t+2-T) ..., (t+m-1-T) each branch current digital quantity sum constantly, take absolute value then.T is a cycle, i _{N (t-T)}Be i _NtThe value of corresponding last cycle, obtain t, t+1, t+2 ..., t+m-1 each branch current digital quantity difference stream sudden change amount absolute value constantly | ∑ Δ I _{φ t}|, | ∑ Δ I _{φ (t+1)}|, ∑ Δ I _{φ (t+2)}| ..., | ∑ Δ I _{φ (t+m-1)}|:

|∑ΔI _φt|＝|(i _1t+i _2t+……+i _nt)-(i _1(t-T)+i _2(t-T)+……+i _n(t-T))|

|∑ΔI _φ(t+1)|＝|(i _1(t+1)+i _2(t+1)+……+i _n(t+1))-(i _1(t+1-T)+i _2(t+1-T)+……+i _n(t+1-T))|

|∑ΔI _φ(t+2)|＝|(i _1(t+2)+i _2(t+2)+……+i _n(t+2))-(i _1(t+2-T)+i _2(t+2-T)+……+i _n(t+2-T))|

……

|∑ΔI _φ(t+m-1)|＝|(i _1(t+m-1)+i _2(t+m-1)+……+i _n(t+m-1))-(i _1(t+m-1-T)+i _2(t+m-1-T)+……+i _n(t+m-1-T))|

Simultaneously, with each branch road t, t+1, t+2 ..., t+m-1 constantly and (t-T), (t+1-T), (t+2-T) ..., (t+m-1-T) difference between current constantly the absolute value addition, obtain each branch road t, t+1, t+2 ..., t+m-1 current digital amount sudden change amount absolute value sum ∑ constantly | Δ I _{φ t}|, ∑ | Δ I _{φ (t+1)}|, ∑ | Δ I _{φ (t+2)}| ..., ∑ | Δ I _{φ (t+m-1)}|:

∑|ΔI _φt|＝|i _1t-i _1(t-T)|+|i _2t-i _2(t-T)|+……+|i _nt-i _n(t-T)|

∑|ΔI _φ(t+1)|＝|i _1(t+1)-i _1(t+1-T)|+|i _2(t+1)-i _2(t+1-T)|+……+|i _n(t+1)-i _n(t+1-T)|

∑|ΔI _φ(t+2)|＝|i _1(t+2)-i _1(t+2-T)|+|i _2(t+2)-i _2(t+2-T)|+……+|i _n(t+2)-i _n(t+2-T)|

……

∑|ΔI _φ(t+m-1)|＝|i _1(t+m-1)-i _1(t+m-1-T)|+|i _2(t+m-1)-i _2(t+m-1-T)|+……+|i _n(t+m-1)-i _n(t+m-1-T)|

With t serves as to differentiate starting point constantly, with each branch road t current digital amount difference stream sudden change constantly amount absolute value | and ∑ Δ I _{φ t}| divided by each branch road t current digital amount sudden change constantly amount absolute value sum ∑ | Δ I _{φ t}| obtain each branch road t change coefficient X constantly ₁

X ₁＝|∑ΔI _φt|/∑|ΔI _φt|

Calculate t+1, t+2 by that analogy respectively ... t+k-1 is the change coefficient X of each branch road constantly ₂, X ₃... X _KValue:

X ₂＝|∑ΔI _φ(t+1)|/∑|ΔI _φ(t+1)|

X ₃＝|∑ΔI _φ(t+2)|/∑|ΔI _φ(t+2)|

……

X _k=| ∑ Δ I _{φ (t+k-1)}|/∑ | Δ I _{φ (t+k-1)}| (span of k is 5～m)

As the amount of sudden change signal enabling, and sudden change amount difference stream forms criterion X ₁+ X ₂＜B (B is a constant, and its span is 0.95～1.15) or the saturated flex point criterion of current transformer X ₂/ X ₁(C is a constant to＜C, its span is 0.45～0.70) wherein there is one can satisfy, then be that the external area error current transformer is saturated, then begin to calculate difference stream discontinuous point, with t and t+1 conventional differential current sum constantly divided by conventional brake electric current sum, gained ratio is t+1 mark K value constantly, and calculates t+2, t+3 successively according to following formula ... each mark K value constantly of t+m-1.Formula is as follows:

K _{Mark (t+1)}=(| ∑ I _{φ t}|+| ∑ I _{φ (t+1)}|)/(∑ | I _{φ t}|+∑ | I _{φ (t+1)}|)

K _{Mark (t+2)}=(| ∑ I _{φ (t+1)}|+| ∑ I _{φ (t+2)}|)/(∑ | I _{φ (t+1)}|+∑ | I _{φ (t+2)}|)

……

K _{Mark (t+m-1)}=(| ∑ I _{φ (t+m-2)}|+| ∑ I _{φ (t+m-1)}|)/(∑ | I _{φ (t+m-2)}|+∑ | I _{φ (t+m-1)}|)

5. above result of calculation is carried out following some differentiation:

1) difference stream discontinuous point is differentiated

Each that calculate in above-mentioned the 4th be the standard K value constantly, if satisfy K _Mark＜A (A is a constant, and its span is 0.2 ~ 0.4), then this is a discontinuous point, promptly in the cycle (20ms), as long as a discontinuous point is arranged, then this section is distinguished for interruption is arranged a compute segment, when all mark K values all satisfy K 〉=A, promptly represents breakpoint continuously.Enter the judgement of next compute segment in this way successively, as breakpoint continuously, then this criterion is passed through.

2) t conventional K value constantly is K _{Conventional t}＞B ' (B ' be constant, its span is 0.52～0.72)

Computing formula according to conventional K value in the 3rd calculates each K constantly _ConventionalThe value, as satisfy above condition then this criterion pass through.

3) harmonic braking criterion:

[(∑I _φt+∑I _φ(t-5))-0.8(∑I _φ(t-2)+∑I _φ(t-3))]/[(|∑I _φt|+|∑I _φ(t-5)|)+

(| ∑ I _{φ (t-2)}|+| ∑ I _{φ (t-3)}|)]＜C ' (C ' be constant, its span is 0.25～0.40)

As result of calculation satisfy following formula then criterion pass through.

T-2 in the following formula, t-3, t-5 represent that sampling instant t phase of wave the last week answers the moment of sampled point.

4) high K value is quickened criterion: K _High＞0.95 (K _HighIntegration for conventional K value in the 20ms)

6. difference stream discontinuous point criterion in the above criterion, conventional K value criterion, when three criterions of harmonic braking criterion are set up simultaneously, the action of protection zone internal fault, if the establishment of high K value acceleration criterion, can direct action.(concrete action logic figure sees accompanying drawing).

24 collection current transformers of ripple (20ms) output end current weekly, and output end current is converted to digital quantity by analog quantity in analog-to-digital mode, utilize these digital quantities to carry out corresponding calculated again;

The foundation of conventional difference trajectory mark scanning method:

Whether (1) difference stream discontinuous point criterion: this criterion is to adopt 2 rolling integration methods of spill current, calculates difference stream discontinuous point, differentiate fault and transfer in the district by the district is outer;

(2) conventional K value criterion: calculate K according to routine _{Conventional t}During＞B ', can allow tripping operation;

(3) harmonic braking criterion: adopt a kind of vector combination (sample frequency 24 points, 15 ° of every bits are in 90 ° of scopes) of 4 points, can reflect the harmonic component level of spill current fast;

(4) high K value is quickened criterion: when high K value integration K in the 20ms＞0.95, can direct export trip.

Embodiment.

With electrical system bus protection equipment is example, and this bus mode of connection is the single busbar connection protection, is total to unit 8, and it has 8 current transformers.

1, presses weekly 24 each current transformer output end currents of gathering in high pressure, the extra-high tension unit of ripple, obtain output end current I _1t, I _2tI _8t, I _{1 (t+1)}, I _{2 (t+1)}I _{8 (t+1)}, I _{1 (t+2)}, I _{2 (t+2)}I _{8 (t+2)}..., I _{1 (t+23)}, I _{2 (t+23)}I _{8 (t+23)}

2, the output end current of Cai Jiing is converted to corresponding digital amount i _1t, i _2tI _8t, i _{1 (t+1)}, i _{2 (t+1)}I _{8 (t+1)}, i _{1 (t+2)}, i _{2 (t+2)}I _{8 (t+2)}..., i _{1 (t+23)}, i _{2 (t+23)}I _{8 (t+23)}Deng.

3. above t each branch current addition is constantly taken absolute value then and obtain conventional differential current, simultaneously each branch current absolute value addition is obtained the conventional brake electric current, formula is as follows:

Conventional differential current=| ∑ I _{φ t}|=| i _1t+ i _2t+ ... + i _8t|

Conventional brake electric current=∑ | I _{φ t}|=| i _1t|+| i _2t|+... + | i _8t|

Than conventional brake electric current, gained ratio is conventional K value K with conventional differential current in the following formula _{Conventional t}, formula is as follows:

K _{Conventional t}=| ∑ I _{φ t}|/∑ | I _{φ t}|

During enforcement by with each sampled point of t substitution constantly as t+1, t+2 ... t+m-1, t-1, t-2 ... t-m+1 can obtain K _{Conventional (t+1)}, K _{Conventional (t+2)}... K _{Conventional (t+m-1)}, K _{Conventional (t-1)}, K _{Conventional (t-2)}... K _{Conventional (t-m+1)}, K wherein _{Conventional (t-1)}, K _{Conventional (t-2)}... K _{Conventional (t-m+1)}For sampling instant t constantly last adjacent cycle conventional K value.

Calculate the conventional K value of each sampled point in the constantly preceding adjacent cycle of t: K according to following formula _{Conventional t}, K _{Conventional (t-1)}, K _{Conventional (t-2)}K _{Conventional (t-23)}To calculate that the corresponding conventional K value addition constantly of each sampled point is divided by the sampling number in this cycle 24 in the adjacent previous cycle of gained, gained ratio is high K value again.Formula is as follows:

K _High=(K _{Conventional t}+ K _{Conventional (t-1)}+ K _{Conventional (t-2)}+ ... + K _{Conventional (t-23)}/ 24

4, again t each branch current digital quantity sum of the moment is deducted i.e. each the branch current digital quantity sum of (t-T) moment of last cycle moment corresponding, take absolute value then.T is a cycle, i _{N (t-T)}Be i _NtThe value of corresponding last cycle obtains t each branch current digital quantity difference stream sudden change amount absolute value constantly | ∑ Δ I _{φ t}|:

|∑ΔI _φt|＝|(i _1t+i _2t+……+i _nt)-(i _1(t-T)+i _2(t-T)+……+i _n(t-T))|

Simultaneously, each branch road in the t moment and (t-T) the absolute value addition of the difference between current in the moment, is obtained each branch road t current digital amount sudden change constantly amount absolute value sum ∑ | Δ I _{φ t}|:

∑|ΔI _φt|＝|i _1t-i _1(t-T)|+|i _2t-i _2(t-T)|+……+|i _nt-i _n(t-T)|

With t serves as to differentiate starting point constantly, with each branch road t current digital amount difference stream sudden change constantly amount absolute value | and ∑ Δ I _{φ t}| divided by each branch road t current digital amount sudden change constantly amount absolute value sum ∑ | Δ I _{φ t}| obtain each branch road t change coefficient X constantly ₁

X ₁＝|∑ΔI _φt|/∑|ΔI _φt|

Calculate t+1, t+2 by that analogy respectively ... t+k-1 is the change coefficient X of each branch road constantly ₂, X ₃... X _KValue:

X ₂＝|∑ΔI _φ(t+1)|/∑|ΔI _φ(t+1)|

X ₃＝|∑ΔI _φ(t+2)|/∑|ΔI _φ(t+2)|

……

X _k=| ∑ Δ I _{φ (t+k-1)}|/∑ | Δ I _{φ (t+k-1)}| (span of k is 5～m)

As the amount of sudden change signal enabling, and sudden change amount difference stream forms criterion X ₁+ X ₂＜1.15 or the saturated flex point criterion of current transformer X ₂/ X ₁＜0.55, wherein there is one can satisfy, then be that the external area error current transformer is saturated, then begin to calculate difference stream discontinuous point, with t and t+1 conventional differential current sum constantly divided by conventional brake electric current sum, gained ratio is t+1 mark K value constantly, and calculates t+1, t+2 successively according to following formula ... each mark K value constantly of t+m-1.Formula is as follows:

K _{Mark (t+1)}=(| ∑ I _{φ t}|+| ∑ I _{φ (t+1)}|)/(∑ | I _{φ t}|+∑ | I _{φ (t+1)}|)

K _{Mark (t+2)}=(| ∑ I _{φ (t+1)}|+| ∑ I _{φ (t+2)}|)/(∑ | I _{φ (t+1)}|+∑ | I _{φ (t+2)}|)

……

K _{Mark (t+m-1)}=(| ∑ I _{φ (t+m-2)}|+| ∑ I _{φ (t+m-1)}|)/(∑ | I _{φ (t+m-2)}|+∑ | I _{φ (t+m-1)}|)

5, above result of calculation is carried out following some differentiation:

1) difference stream discontinuous point is differentiated

Each that calculate in above-mentioned the 4th be the standard K value constantly, if satisfy K _Mark＜0.3, then this is a discontinuous point, and promptly in the cycle (20ms), as long as a discontinuous point is arranged, then this section is distinguished for interruption is arranged a compute segment, when all mark K values all satisfy K 〉=0.3, promptly represents breakpoint continuously.Enter the judgement of next compute segment in this way successively, as breakpoint continuously, then this criterion is passed through.

2) t conventional K value constantly is K _{Conventional t}＞0.62

Computing formula according to conventional K value in the 3rd calculates each K constantly _ConventionalThe value, as satisfy above condition then this criterion pass through.

3) harmonic braking criterion:

(∑I _φt+∑I _φ(t-5)-0.8(∑I _φ(t-2)+∑I _φ(t-3)]/[(|∑I _φt|+|∑I _φ(t-5)|)+

(|∑I _φ(t-2)|+|∑I _φ(t-3)|)]＜0.30

As result of calculation satisfy following formula then criterion pass through.

4) high K value is quickened criterion: K _High＞0.95 (K _HighBe the integration of conventional K value in the 20ms)

6, indifference stream discontinuous point criterion in the above criterion, conventional K value criterion, when three criterions of harmonic braking criterion are set up simultaneously, the action of protection zone internal fault, if the establishment of high K value acceleration criterion, can direct action.(concrete action logic figure sees accompanying drawing)

Claims (4)

1. the saturated routine difference trajectory mark of anti-current instrument transformer scans method of discrimination, it is characterized in that its differentiation process is as follows:

1) by each the branch current instrument transformer output end current in the time interval collection high pressure of setting, the extra-high tension unit, obtains output end current I _1t, I _2tI _Nt, I _{1 (t+1)}, I _{2 (t+1)}I _{N (t+1)}, I _{1 (t+2)}, I _{2 (t+2)}I _{N (t+2)}..., I _{1 (t+m-1)}, I _{2 (t+m-1)}I _{N (t+m-1)}, n is the sequence number of each branch current instrument transformer, m is the sampling number in each cycle;

2) output end current of gathering is converted to corresponding digital amount i _1t, i _2tI _Nt, i _{1 (t+1)}, i _{2 (t+1)}I _{N (t+1)}, i _{1 (t+2)}, i _{2 (t+2)}I _{N (t+2)}..., i _{1 (t+m-1)}, i _{2 (t+m-1)}I _{N (t+m-1)}

3) with t, t+1, t+2 ... t+m-1 each branch current addition constantly takes absolute value then and obtains conventional differential current of this moment, and each branch current absolute value addition constantly simultaneously obtains this moment conventional brake electric current, and each formula constantly is as follows:

T conventional differential current of the moment=| ∑ I _{φ t}|=| i _1t+ i _2t+ ... + i _Nt|

T+1 conventional differential current of the moment=| ∑ I _{φ (t+1)}|=| i _{1 (t+1)}+ i _{2 (t+1)}+ ... + i _{N (t+1)}|

T+2 conventional differential current of the moment=| ∑ I _{φ (t+2)}|=| i _{1 (t+2)}+ i _{2 (t+2)}+ ... + i _{N (t+2)}|

……

T+m-1 conventional differential current of the moment=| ∑ I _{φ (t+m-1)}|=| i _{1 (t+m-1)}+ i _{2 (t+m-1)}+ ... + i _{N (t+m-1)}|

T is conventional brake electric current=∑ constantly | I _{φ t}|=| i _1t|+| i _2t|+... + | i _Nt|

T+1 is conventional brake electric current=∑ constantly | I _{φ (t+1)}|=| i _{1 (t+1)}|+| i _{2 (t+1)}|+... + | i _{N (t+1)}|

T+2 is conventional brake electric current=∑ constantly | I _{φ (t+2)}|=| i _{1 (t+2)}|+| i _{2 (t+2)}|+... + | i _{N (t+2)}|

……

T+m-1 is conventional brake electric current=∑ constantly | I _{φ (t+m-1)}|=| i _{1 (t+m-1)}|+| i _{2 (t+m-1)}|+... + | i _{N (t+m-1)}|

Than conventional brake electric current, gained ratio is conventional K value with conventional differential current, and the conventional K value of each sampling instant is as follows:

T is conventional K value K constantly _{Conventional t}=| ∑ I _{φ t}|/∑ | I _{φ t}|

T+1 is conventional K value K constantly _{Conventional (t+1)}=| ∑ I _{φ (t+1)}|/∑ | I _{φ (t+1)}|

T+2 is conventional K value K constantly _{Conventional (t+2)}=| ∑ I _{φ (t+2)}|/∑ | I _{φ (t+2)}|

……

T+m-1 is conventional K value K constantly _{Conventional (t+m-1)}=| ∑ I _{φ (t+m-1)}|/∑ | I _{φ (t+m-1)}|

Calculate the conventional K value of each sampling instant by following formula, calculate the radix of high K value as next cycle sampled point; High K value equals the conventional K value addition of last each sampled point of cycle divided by the sampling number in this cycle, and computing formula is as follows:

K _High=(K _{Conventional t}+ K _{Conventional (t-1)}+ K _{Conventional (t-2)}+ ... + K _{Conventional (t-m+1)})/m

M is the sampling number in the last cycle of sampling instant t in the formula;

4) with above t, t+1, t+2 ..., t+m-1 constantly each branch current digital quantity sum deduct last cycle moment corresponding promptly (t-T), (t+1-T), (t+2-T) ..., (t+m-1-T) each branch current digital quantity sum constantly, take absolute value then; T is a cycle, i _{N (t-T)}Be i _NtThe value of corresponding last cycle, obtain t, t+1, t+2 ..., t+m-1 each branch current digital quantity difference stream sudden change amount absolute value constantly | ∑ Δ I _{φ t}|, | ∑ Δ I _{φ (t+1)}|, | ∑ Δ I _{φ (t+2)}| ..., | ∑ Δ I _{φ (t+m-1)}|:

|∑ΔI _φt|＝|(i _1t+i _2t+……+i _nt)-(i _1(t-T)+i _2(t-T)+……+i _n(t-T))|

|∑ΔI _φ(t+1)|＝|(i _1(t+1)+i _2(t+1)+……+i _n(t+1))-(i _1(t+1-T)+i _2(t+1-T)+……+i _n(t+1-T))|

|∑ΔI _φ(t+2)|＝|(i _1(t+2)+i _2(t+2)+……+i _n(t+2))-(i _1(t+2-T)+i _2(t+2-T)+……+i _n(t+2-T))|

……

|∑ΔI _φ(t+m-1)|＝|(i _1(t+m-1)+i _2(t+m-1)+……+i _n(t+m-1))-(i _1(t+m-1-T)+i _2(t+m-1-T)+……+i _n(t+m-1-T))|

Simultaneously, with each branch road t, t+1, t+2 ..., t+m-1 constantly and (t-T), (t+1-T), (t+2-T) ..., (t+m-1-T) difference between current constantly the absolute value addition, obtain each branch road t, t+1, t+2 ..., t+m-1 current digital amount sudden change amount absolute value sum ∑ constantly | Δ I _{φ t}|, ∑ | Δ I _{φ (t+1)}|, ∑ | Δ I _{φ (t+2)}| ..., ∑ | Δ I _{φ (t+m-1)}|:

∑|ΔI _φt|＝|i _1t-i _1(t-T)|+|i _2t-i _2(t-T)|+……+|i _nt-i _n(t-T)|

∑|ΔI _φ(t+1)|＝|i _1(t+1)-i _1(t+1-T)|+|i _2(t+1)-i _2(t+1-T)|+……+|i _n(t+1)-i _n(t+1-T)|

∑|ΔI _φ(t+2)|＝|i _1(t+2)-i _1(t+2-T)|+|i _2(t+2)-i _2(t+2-T)|+……+|i _n(t+2)-i _n(t+2-T)|

……

∑|ΔI _φ(t+m-1)|＝|i _1(t+m-1)-i _1(t+m-1-T)|+|i _2(t+m-1)-i _2(t+m-1-T)|+……+|i _n(t+m-1)-i _n(t+m-1-T)|

With t serves as to differentiate starting point constantly, with each branch road t current digital amount difference stream sudden change constantly amount absolute value | and ∑ Δ I _{φ t}| divided by each branch road t current digital amount sudden change constantly amount absolute value sum ∑ | Δ I _{φ t}| obtain each branch road t change coefficient X constantly ₁:

X ₁＝|∑ΔI _φt|/∑|ΔI _φt|

Calculate t+1, t+2 by that analogy respectively ... t+k-1 is the change coefficient X of each branch road constantly ₂, X ₃... X _KValue:

X ₂＝|∑ΔI _φ(t+1)|/∑|ΔI _φ(t+1)|

X ₃＝|∑ΔI _φ(t+2)|/∑|ΔI _φ(t+2)|

……

X _k=| ∑ Δ I _{φ (t+k-1)}|/∑ | Δ I _{φ (t+k-1)}|, the span of k is 5～m;

As the amount of sudden change signal enabling, and sudden change amount difference stream forms criterion X ₁+ X ₂＜B, B are constant, and its span is 0.95～1.15, or the saturated flex point criterion of current transformer X ₂/ X ₁＜C, C is a constant, its span is 0.45～0.70, wherein having one can satisfy, then is that the external area error current transformer is saturated, then begins to calculate difference stream discontinuous point, with t and t+1 conventional differential current sum constantly divided by conventional brake electric current sum, gained ratio is t+1 mark K value constantly, and calculates t+2, t+3 successively according to following formula ... each mark K value constantly of t+m-1, formula is as follows:

K _{Mark (t+1)}=(| ∑ I _{φ t}|+| ∑ I _{φ (t+1)}|)/(∑ | I _{φ t}|+∑ | I _{φ (t+1)}|)

K _{Mark (t+2)}=(| ∑ I _{φ (t+1)}|+| ∑ I _{φ (t+2)}|)/(∑ | I _{φ (t+1)}|+∑ | I _{φ (t+2)}|)

……

K _{Mark (t+m-1)}=(| ∑ I _{φ (t+m-2)}|+| ∑ I _{φ (t+m-1)}|)/(∑ | I _{φ (t+m-2)}|+∑ | I _{φ (t+m-1)}|)

5) above result of calculation is carried out following some differentiation:

A, difference stream discontinuous point are differentiated

Calculate in above-mentioned the 4th each the time blaze K value, if satisfy K _Mark＜A, A are constant, and its span is 0.2～0.4, and then this is a discontinuous point, and promptly in cycle 20ms, as long as a discontinuous point is arranged, then this section is distinguished for interruption is arranged a compute segment, when all mark K values all satisfy K 〉=A, promptly represent breakpoint continuously; Enter the judgement of next compute segment in this way successively, as breakpoint continuously, then this criterion is passed through;

B, t conventional K value constantly is K _{Conventional t}＞B ', B ' are constant, and its span is 0.52～0.72;

Computing formula according to conventional K value in the 3rd calculates each K constantly _ConventionalThe value, as satisfy above condition then this criterion pass through;

C, harmonic braking criterion:

[(∑I _φt+∑I _φ(t-5))-0.8(∑I _φ(t-2)+∑I _φ(t-3))]/[(|∑I _φt|+|∑I _φ(t-5)|)

+

(|∑I _φ(t-2)|+|∑I _φ(t-3)|)]＜C′，

C ' is a constant in the formula, and its span is 0.25～0.40, as result of calculation satisfy following formula then criterion pass through;

D, high K value are quickened criterion: K _High＞0.95;

6) difference stream discontinuous point criterion in the above criterion, conventional K value criterion, when three criterions of harmonic braking criterion are set up simultaneously, the action of protection zone internal fault, if the establishment of high K value acceleration criterion, can direct action.

2. the routine difference trajectory mark scanning method of discrimination that anti-current instrument transformer according to claim 1 is saturated is characterized in that:

Ripple 20ms weekly, 24 collection current transformer output end currents, and output end current is converted to digital quantity by analog quantity in analog-to-digital mode, utilize these digital quantities to carry out corresponding calculated again;

The foundation of conventional difference trajectory mark scanning method:

Whether (1) difference stream discontinuous point criterion: this criterion is to adopt 2 rolling integration methods of spill current, calculates difference stream discontinuous point, differentiate fault and transfer in the district by the district is outer;

(2) conventional K value criterion: calculate K according to routine _{Conventional t}During＞B ', can allow tripping operation;

(3) harmonic braking criterion: adopt a kind of vector combination of 4 points, sample frequency 24 points, 15 ° of every bits in 90 ° of scopes, can reflect the harmonic component level of spill current fast;

(4) high K value is quickened criterion: when high K value integration K in the 20ms＞0.95, can direct export trip.

3. the routine difference trajectory mark scanning method of discrimination that anti-current instrument transformer according to claim 1 is saturated is characterized in that the described time interval equates that it equals weekly the time of ripple divided by sampling number.

4. the routine difference trajectory mark scanning method of discrimination that anti-current instrument transformer according to claim 1 is saturated is characterized in that described sampling number is 24 points.

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