CN104659767A - Protection method for line unit of triangle looped network by utilizing sequence overlap difference - Google Patents
Protection method for line unit of triangle looped network by utilizing sequence overlap difference Download PDFInfo
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- CN104659767A CN104659767A CN201410619123.3A CN201410619123A CN104659767A CN 104659767 A CN104659767 A CN 104659767A CN 201410619123 A CN201410619123 A CN 201410619123A CN 104659767 A CN104659767 A CN 104659767A
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- 238000010276 construction Methods 0.000 description 2
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Abstract
The invention relates to a protection method for a line unit of a triangle looped network by utilizing a sequence overlap difference, and belongs to the technical field of power system relay protection. The protection method comprises the following steps: when a single-phase grounding failure occurs in the triangle looped network, through directional elements R1 and R2, R3 and R4 and R5 and R6 at an M end, an N end and a Q end, obtaining six sets of line mold voltages and line mold currents, intercepting the data of the line mold voltage and the data of the line mold current in a short time window after failure, respectively performing the sequence overlap difference on the intercepted data of the line mold voltage and the intercepted data of the line mold current, and respectively multiplying a differential value of the line mold voltage and a differential value of the line mold current so as to obtain six sets of a series of wave heads on a timer shaft; when polarities of first wave heads in the wave head series corresponding to two directional elements in the same line are negative, determining that the line failure belongs to the internal failure, and otherwise, the line failure belongs to the external failure. Plenty of simulation experiments prove that the protection method has better applicability for protecting the line of the triangle looped network.
Description
Technical field
The present invention relates to a kind of triangle loop grid cell protection method utilizing overlapping sequences difference, belong to Relay Protection Technology in Power System field.
Background technology
Along with the continuous expansion of electric power system scale and the continuous rising of electric pressure, people require more and more higher to the protection of power network line.Fault excises faulty line after occurring at faster speed exactly, and protection system safe operation is the unremitting pursue of electric network protection.When electric power system is broken down, be the fault component that can produce from power frequency to high frequency, in these high fdrequency components, contain a large amount of information, just like the type of fault, position, direction, degree and duration etc.Effective extraction of these information has become with application the important means improving relaying protection performance, utilizes the transient of line fault can improve protection speed to a greater extent to form route protection criterion.In recent years, along with the development of the signal transacting instruments such as DSP technology and wavelet analysis, the ultra-high speed protection new principle of a series of circuit complete fibre based on single-end electrical quantity occurs in succession.For the protection scheme that these are new, most research is all analyzed using two-termial line as research object, and demonstrates applicability and the validity of protection scheme.
Distance relay is widely used in the protection of two end transmission lines, and protection philosophy make use of the phase place of protected district end bucking voltage when fault occurs by this feature of sudden change of generation 180 °.Comparatively common direction component also comprises positive sequence fault component directional relay, negative phase-sequence fault component directional relay, zero-sequence fault component directional relay and directional impedance relay etc. at present.In order to ensure the reliability of power supply, triangle looped network has a wide range of applications in transmission system, and due to the special construction of triangle looped network, some traditional guard methods are difficult to implement available protecting to it.Therefore, a kind of effective guard method of special construction exploration for triangle looped network is imperative.
Summary of the invention
The technical problem to be solved in the present invention is three client informations of line mode voltage and line mould electric current when making full use of triangle ring network fault; jump signal is extracted by the means of overlapping sequences difference; and then propose a kind of based on direction sudden change be applicable to T get access to grid protection method, to improve applicability and the reliability of guard method.
Technical scheme of the present invention is: a kind of triangle loop grid cell protection method utilizing overlapping sequences difference, during triangle looped network generation single phase ground fault, by the direction component R of M, N, Q end
1and R
2, R
3and R
4, R
5and R
6obtain six groups of line mode voltages and line mould electric current, line mode voltage after intercepting fault in short time-window and line mould current data carry out overlapping sequences difference to it respectively, the difference value of line mode voltage is multiplied with line mould difference between current score value respectively, obtain six groups of a series of wave heads on a timeline, when the Mintrop wave head polarity in the wave head series corresponding to the both direction element on same circuit is all negative, judge this line fault, belong to troubles inside the sample space, otherwise be external area error.
Concrete steps are:
A. during triangle looped network generation single phase ground fault, by the direction component R of M, N, Q end
1and R
2, R
3and R
4, R
5and R
6obtain six groups of line mode voltages and line mould electric current:
with
, j=1,2 ..., 6;
B. the line mode voltage after intercepting fault in short time-window and line mould current data carry out overlapping sequences difference to it respectively, obtain difference value and are respectively
(n) and
(n), j=1,2 ..., 6;
C. the difference value of line mode voltage is carried out being multiplied obtaining with line mould difference between current score value respectively
j=1,2 ..., 6,
n () shows as a series of wave head at time shaft, first wave head chosen in six groups of wave head series is research object, uses sign function
j=1,2 ..., 6, represent the polarity of first wave head in six groups of wave head series respectively, when its value is-1, represent that wave head polarity is negative; When its value is+1, represent that wave head polarity is just;
D. when
And
Then circuit MN fault;
When
And
Then circuit NQ fault;
When
And
Then circuit QM fault;
If when above-mentioned condition meets one, be judged to be troubles inside the sample space;
If when above-mentioned condition does not all meet, be judged to be external area error.
Principle of the present invention is:
Overlapping sequences difference is a kind of conversion based on calculus of differences, can be described as:
In formula, S
mn m jump that () is signal divides, j=1,2,3 ... m+1 is difference order, and m is the exponent number of difference, and Q (n) is primary signal, n=1,2,3 ... N, N are that original signal samples is counted, (c
j)
mfor overlapping sequences differential transformation coefficient.Coefficient (c
j)
mvalue be (c
1)
m=(c
m+1)
m=1, (c
2)
m=m, (c
2)
m=(c
j)
m-1+ (c
j-1)
m-1, Σ (-1)
j+1(c
j)
m=0.Therefore, when m gets 1, can DC component be reduced, when m gets 3, power frequency 50Hz component can be eliminated.M value is larger, and the amplitude extracting the high frequency transient amount obtained is larger.The overlapping sequences difference that the present invention uses all adopts 4 jumps to divide, and its conversion expression formula is:
S
4＝Q(n)-4×Q(n-1)+6×Q(n-2)-4×Q(n-3)+Q(n-4) (2)
Triangle loop grid model as shown in Figure 1, for circuit MN holds, supposes positive direction fault F occurs
1, then by R
1and R
2the line mode voltage obtained and line mould electric current are after carrying out overlapping sequences difference respectively, and the Mintrop wave head polarity in the wave head sequence that its product obtains is negative simultaneously; If there is reverse direction failure F
4, then by R
1and R
2the line mode voltage obtained and line mould electric current are after carrying out overlapping sequences difference respectively, and the Mintrop wave head polarity in the wave head sequence that its product obtains is one positive one negative.For circuit NQ and QM, by arranging the fault F of different directions
2, F
3and F
5, F
6, by R
3and R
4, R
5and R
6the line mode voltage obtained and line mould electric current are after carrying out overlapping sequences difference respectively, and the Mintrop wave head polarity in the wave head sequence that its product obtains possesses above-mentioned character equally.If by R
1, R
2, R
3, R
4, R
5and R
6the polarity sign function of corresponding Mintrop wave head
j=1,2 ..., 6 define, so when
and
time, judge then circuit MN fault; When
And
Time, judge circuit NQ fault; When
And
time, judge circuit QM fault.Because circuit MN, NQ, QM all belong to protection section, therefore in above-mentioned three conditions one be just judged to be troubles inside the sample space when meeting, three are judged to be external area error when all not meeting.
The invention has the beneficial effects as follows:
1. the present invention takes full advantage of the fault message of triangle loop grid three end, and the conbined usage of multichannel information improves the reliability of protection;
2. the present invention employs the product of line mode voltage and line mould electric current in essence, by signal appropriateness being amplified, when effectively overcoming weak output signal, is used alone the deficiency that one of them amount not easily detects analysis.
3. present invention uses overlapping sequences differential transformation, direction Sudden Changing Rate is effectively extracted, certain depth reduces the interference of noise signal, improve the reliability of analysis, ensure the accuracy of guard method.
Accompanying drawing explanation
Fig. 1 is that the T of the embodiment of the present invention 1,2,3 gets access to grid circuit model;
Fig. 2 is R in the embodiment of the present invention 1
1measure the overlapping difference result of the burst obtained;
Fig. 3 is R in the embodiment of the present invention 1
2measure the overlapping difference result of the burst obtained;
Fig. 4 is R in the embodiment of the present invention 1
3measure the overlapping difference result of the burst obtained;
Fig. 5 is R in the embodiment of the present invention 1
4measure the overlapping difference result of the burst obtained;
Fig. 6 is R in the embodiment of the present invention 1
5measure the overlapping difference result of the burst obtained;
Fig. 7 is R in the embodiment of the present invention 1
6measure the overlapping difference result of the burst obtained.
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described.
Utilize a triangle loop grid cell protection method for overlapping sequences difference, during triangle looped network generation single phase ground fault, by the direction component R of M, N, Q end
1and R
2, R
3and R
4, R
5and R
6obtain six groups of line mode voltages and line mould electric current, line mode voltage after intercepting fault in short time-window and line mould current data carry out overlapping sequences difference to it respectively, the difference value of line mode voltage is multiplied with line mould difference between current score value respectively, obtain six groups of a series of wave heads on a timeline, when the Mintrop wave head polarity in the wave head series corresponding to the both direction element on same circuit is all negative, judge this line fault, belong to troubles inside the sample space, otherwise be external area error.
Concrete steps are:
A. during triangle looped network generation single phase ground fault, by the direction component R of M, N, Q end
1and R
2, R
3and R
4, R
5and R
6obtain six groups of line mode voltages and line mould electric current:
with
j=1,2 ..., 6;
B. the line mode voltage after intercepting fault in short time-window and line mould current data carry out overlapping sequences difference to it respectively, obtain difference value and are respectively
(n) and
(n), j=1,2 ..., 6;
C. the difference value of line mode voltage is carried out being multiplied obtaining with line mould difference between current score value respectively
show as a series of wave head at time shaft, first wave head chosen in six groups of wave head series is research object, uses sign function
j=1,2 ..., 6, represent the polarity of first wave head in six groups of wave head series respectively, when its value is-1, represent that wave head polarity is negative; When its value is+1, represent that wave head polarity is just;
D. when
And
Then circuit MN fault;
When
And
Then circuit NQ fault;
When
And
Then circuit QM fault;
If when above-mentioned condition meets one, be judged to be troubles inside the sample space;
If when above-mentioned condition does not all meet, be judged to be external area error.
Embodiment 1: embodiment 1: set up triangle loop grid model as shown in Figure 1.In system, l
mN=100km, l
nQ=70km, l
qM=80km, l
pM=70km.Rated current positive direction is that bus points to circuit.Now suppose that circuit MN section holds 40km that single phase ground fault F occurs apart from M
1, initial phase angle is 90 °, sample rate 20kHz.By the direction component R of M, N, Q end
1and R
2, R
3and R
4, R
5and R
6obtain six groups of line mode voltages and line mould electric current, line mode voltage after intercepting fault in 2ms window and line mould current data carry out 4 rank overlapping sequences difference to it respectively, the difference value of line mode voltage is multiplied with line mould difference between current score value respectively, obtain six groups of a series of wave heads on a timeline, as illustrated in figs. 2-7.By Fig. 2-7 draw the polarity of Mintrop wave head in each group of wave head series and fault section result of determination as shown in table 1.
Table 1 fault F
1time direction component R
1~ R
6comprehensive descision result
Judged result is consistent with hypothesis, correct judgment.
Embodiment 2: the triangle loop grid model identical with embodiment 1.Now suppose that circuit NQ section holds 30km that single phase ground fault F occurs apart from N
2, initial phase angle is 90 °, sample rate 20kHz.By the direction component R of M, N, Q end
1and R
2, R
3and R
4, R
5and R
6obtain six groups of line mode voltages and line mould electric current, line mode voltage after intercepting fault in 2ms window and line mould current data carry out 4 rank overlapping sequences difference to it respectively, the difference value of line mode voltage is multiplied with line mould difference between current score value respectively, obtains six groups of a series of wave heads on a timeline.In each group of wave head series the polarity of Mintrop wave head and fault section result of determination as shown in table 2.
Table 2 fault F
2time direction component R
1~ R
6comprehensive descision result
Judged result is consistent with hypothesis, correct judgment.
Embodiment 3: the triangle loop grid model identical with embodiment 1.Now suppose circuit PM holds 50km that single phase ground fault F occurs apart from M
4, initial phase angle is 90 °, sample rate 20kHz.By the direction component R of M, N, Q end
1and R
2, R
3and R
4, R
5and R
6obtain six groups of line mode voltages and line mould electric current, line mode voltage after intercepting fault in 2ms window and line mould current data carry out 4 rank overlapping sequences difference to it respectively, the difference value of line mode voltage is multiplied with line mould difference between current score value respectively, obtains six groups of a series of wave heads on a timeline.In each group of wave head series the polarity of Mintrop wave head and fault section result of determination as shown in table 3.
Table 3 fault F
4time direction component R
1~ R
6comprehensive descision result
Judged result is consistent with hypothesis, 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 that those of ordinary skill in the art possess, various change can also be made under the prerequisite not departing from present inventive concept.
Claims (2)
1. utilize a triangle loop grid cell protection method for overlapping sequences difference, it is characterized in that: during triangle looped network generation single phase ground fault, by the direction component R of M, N, Q end
1and R
2, R
3and R
4, R
5and R
6obtain six groups of line mode voltages and line mould electric current, line mode voltage after intercepting fault in short time-window and line mould current data carry out overlapping sequences difference to it respectively, the difference value of line mode voltage is multiplied with line mould difference between current score value respectively, obtain six groups of a series of wave heads on a timeline, when the Mintrop wave head polarity in the wave head series corresponding to the both direction element on same circuit is all negative, judge this line fault, belong to troubles inside the sample space, otherwise be external area error.
2. the triangle loop grid cell protection method utilizing overlapping sequences difference according to claim 1, is characterized in that concrete steps are:
A. during triangle looped network generation single phase ground fault, by the direction component R of M, N, Q end
1and R
2, R
3and R
4, R
5and R
6obtain six groups of line mode voltages and line mould electric current:
with
j=1,2 ..., 6;
B. the line mode voltage after intercepting fault in short time-window and line mould current data carry out overlapping sequences difference to it respectively, obtain difference value and are respectively
with
j=1,2 ..., 6;
C. the difference value of line mode voltage is carried out being multiplied obtaining with line mould difference between current score value respectively
j=1,2 ..., 6,
show as a series of wave head at time shaft, first wave head chosen in six groups of wave head series is research object, uses sign function
j=1,2 ..., 6, represent the polarity of first wave head in six groups of wave head series respectively, when its value is-1, represent that wave head polarity is negative; When its value is+1, represent that wave head polarity is just;
D. when
And
Then circuit MN fault;
When
And
Then circuit NQ fault;
When
And
Then circuit QM fault;
If when above-mentioned condition meets one, be judged to be troubles inside the sample space;
If when above-mentioned condition does not all meet, be judged to be external area error.
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Cited By (4)
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| CN104868501A (en) * | 2015-06-11 | 2015-08-26 | 中国电力工程顾问集团华东电力设计院有限公司 | Power grid system including ring network, and faulty line judgment method |
| CN106353629A (en) * | 2016-08-02 | 2017-01-25 | 昆明理工大学 | Transient-state quantity polarity comparison type bus protection method on basis of sequence overlapping and differential transformation |
| CN113138320A (en) * | 2021-04-09 | 2021-07-20 | 南京南瑞继保电气有限公司 | Double-end traveling wave distance measurement method suitable for looped network |
| US11435411B2 (en) | 2019-04-08 | 2022-09-06 | Hitachi Energy Switzerland Ag | Time domain distance protection based on polarity comparison for power transmission lines |
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| CN113138320B (en) * | 2021-04-09 | 2022-10-28 | 南京南瑞继保电气有限公司 | Double-end traveling wave distance measurement method suitable for looped network |
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