CN102623972A - Differential protection method using single-ended transient signal high-frequency component throughput of transmission line - Google Patents

Abstract

The invention relates to a differential protection method using single-ended transient signal high-frequency component throughputs of a transmission line, belonging to a single-ended transient protection scheme for a power transmission line. When the line is in short circuit, a large number of high-frequency signals are generated due to a fault and are propagated to the two ends of the line; and as a bus has ground distributed capacitance, the high-frequency signals are remarkably reduced when the high-frequency signals pass through the bus, and high-frequency component values detected at a proximal fault side of the bus are always greater than those detected at a distal fault side of the bus. According to the differential protection method, fault signals of the inner side and the outer side of the bus at a line protection mounting position are acquired by using the above-mentioned principle, fault transient signals are subjected to lossless segmentation by using a perfect reconstruction filter bank, then, the difference value of certain throughputs of subband components of the inner side and the outer side of the bus is calculated, and whether the fault is an internal fault or an external fault is judged according to a majority voting mechanism by using the difference value; and signals for constructing criteria are a plurality of subband high-frequency signals covering the full high-frequency band, and subband frequencies can be adaptively adjusted along with the change of a sampling frequency. The differential protection method has the advantages that the scheme is simple and reliable, the line of total length can be protected, the requirements on the distributed capacitance of the bus are low, and the fault tolerance and the reliability are enhanced from principle and hardware implementation manners.

Description

The single-ended transient signal high fdrequency component of transmission line treating capacity differential protecting method

Technical field

The present invention relates to the electric power transmission line resist technology; Refer more particularly to poor (transient current high fdrequency component treating capacity poor of the single-ended transient high frequency component treating capacity of utilizing transmission line; Or transient voltage high fdrequency component treating capacity is poor); Thereby realize that the protection zone internal fault still is the identification of external area error, with the method for protecting.

Background technology

Utilize the transient protection of line fault transient high frequency component structure not only to improve the protection responsiveness to a greater extent, also have insensitive to fault type, abort situation, fault impedance, fault initial angle, do not receive that current transformer is saturated, the influence of power frequency short circuit level etc.Along with signal processing means constantly improves raising, transient protection has obtained very big development.In recent years, Chinese scholars has proposed a series of ultrahigh speed protections based on line one-end transient state amount, wherein is typically the single-ended amount transient protection of realizing based on different high band energy ratio the most.When this principle utilized transient signal to pass through bus, high fdrequency component wherein decayed manyly, and low frequency component is decayed fewly, and is different according to energy ratio like this, thereby judges and distinguish interior/external area error.There is inherent shortcoming in this principle; The practical power systems failure condition is very complicated and changeable; The high fdrequency component composition and the low frequency component composition that comprise in the transient signal that produces under the different faults situation differ greatly; Cause the energy ratio of the high and low frequency component of the outer fault of some situation inferior segment; The energy ratio of high and low frequency component is a lot of greatly in the time of maybe be than troubles inside the sample space, causes the energy ratio of high and low frequency component when circuit one end detects external area error bigger than the ratio under the troubles inside the sample space situation on the contrary, causes the protection misoperation.Simultaneously; Because what the method that adopts energy ratio to constitute failure criterion was used is division; Be easy to like this amplify small-signal interference (such as: 1 equals 100 divided by 0.01), make the ratio that calculates actual response actual conditions, instability easily fully; Anti-interference is poor, finally causes the protective device reliability to reduce.In addition, but after two very greatly very approaching amounts of numerical value own are divided by ratio but very little relatively (such as: 10500 equal 1.0500 divided by 10000), be unfavorable for protecting the setting of setting value.Other is based on the method for single-ended Transient Signal Processing amount ratio, like methods such as the unusual degree ratio of ratio, transient signal of transient signal entropy, signal complexity ratios, all exists similar inherent shortcoming with not enough on the principle.

Therefore, fast to traditional differential protection exercise speed not enough, at present stable inadequately, the shortcoming and defect reliably inadequately of transient protection performance needs the better ultrahigh speed transient protection new method of research performance.

Summary of the invention

The objective of the invention is to overcome the prior art deficiency; A kind of single-ended transient signal high fdrequency component treating capacity differential protecting method is provided; Be applied to protect the various components and parts in the electric power system, be particularly useful for transmission line, can improve the rapidity of protection action greatly; Improve the reliability of protection action simultaneously to greatest extent, the total length of ability protection circuit.

The basic principle of the single-ended transient signal high fdrequency component of transmission line treating capacity differential protecting method is as protection zone MN intersegmental part F ₁When point breaks down; Produce a large amount of high-frequency current/voltage signals, Transient High Frequency Signal is propagated to both sides, through bus M, N the time; Owing on the bus bigger distributed capacitance is over the ground arranged; A big chunk in the transient high frequency component can be bypassed, and for the Transient High Frequency Signal of same frequency range, always is better than the detected Transient High Frequency Signal in the outside in the inboard detected Transient High Frequency Signal of bus.Can construct the ultrahigh speed transient protection that has reliable and stable, can the protection circuit total length according to this rule.

Electric current (or voltage) the transient high frequency component of the inside and outside both sides of circuit bus is introduced protective device respectively, utilize complete restructuring analysis bank of filters with transient current (or voltage) signal lossless be divided into a low frequency sub-band component and a plurality of high-frequency sub-band component; And the transient high frequency amount of each frequency range suitably handled obtain the high fdrequency component treating capacity; Then that the treating capacity of the transient high frequency component of the inside and outside both sides of bus respective channel is poor; Through majority voting mechanism, judgement is troubles inside the sample space, or external area error by difference, and whether decision sends trip signal; This invents single-ended transient signal high fdrequency component treating capacity differential protecting method reliability height, can the protection circuit total length.Because the structure of this invention guard method criterion is based on the transient high frequency component of having rejected power frequency component, thereby guaranteed the ultrahigh speed property that protection is moved.

For achieving the above object; Technical scheme of the present invention is a kind of single-ended transient signal high fdrequency component treating capacity differential protecting method, and corresponding a plurality of frequency range high fdrequency component treating capacities and their difference constitute the differential protection criterion in the transient current (or voltage) of the inside and outside both sides of employing bus.When the value of transient high frequency component treating capacity greater than setting value, promptly work as | P_I _Hf|＞P _Qd(or | P_U _Hf|＞P _Qd) time, expression is broken down, and starts protection, P_I _Hf(P_U _Hf) treating capacity of a certain frequency range transient state amount of expression transient current (voltage), P _QdBe protection startup value.Then, the structure that carries out criterion according to majority voting mechanism with reference to being described below (following is example explanation criterion building method with the bank of filters with three hf channels):

When Act=1, be judged to troubles inside the sample space; When Act=0, be judged to external area error.Act=((diff wherein ₁＞k _Set1)+(diff ₂＞k _Set2)) ((diff ₂＞k _Set2)+(diff ₃＞k _Set3)) ((diff ₁＞k _Set1)+diff ₃＞k _Set3)), diff ₁=P_I _2hf1-P_I _1hf1, diff ₂=P_I _2hf2-P_I _1hf2, diff ₃=P_I _2hf3-P_I _1hf3(or diff ₁=P_U _2hf1-P_U _1hf1, diff ₂=P_U _2hf2-P_U _1hf2, diff ₃=P_U _2hf3-P_U _1hf3).

P_I in the formula _1hf1, P_I _1hf2, P_I _1hf3, P_I _2hf1, P_I _2hf2, P_I _2hf3For the circuit bus is outer, the electric current I of interior both sides ₁, I ₂Middle transient high frequency component I _1hf1, I _1hf2, I _1hf3, I _2hf1, I _2hf2, I _2hf3Energy or entropy or complexity or unusual degree or modulus maximum or other handle a kind of (P_U in the value _1hf1, P_U _1hf2, P_U _1hf3, P_U _2hf1, P_U _2hf2, P_U _2hf3Voltage U for the bus both sides ₁, U ₂Medium-high frequency component U _1hf1, U _1hf2, U _1hf3, U _2hf1, U _2hf2, U _2hf3, U _3hf1, U _3hf2, U _3hf3, U _4hf1, U _4hf2, U _4hf3Energy or entropy or complexity or unusual degree or modulus maximum or other handle a kind of in the value).k _Set1, k _Set2, k _Set3Be the differential action setting value of each passage of transient high frequency component treating capacity differential protection.Diff ₁, diff ₂, diff ₃, represent the energy difference of each passage transient high frequency component treating capacity of the inside and outside both sides of bus or entropy is poor or the poor or unusual degree of complexity is poor or modulus maximum is poor or other difference respectively.

The single-ended transient signal high fdrequency component of the transmission line treating capacity differential protecting method that the present invention proposes can produce following beneficial effect:

1, this guard method adopts complete reconfigurable filter group that the fault transient signal is carried out lossless analysis, does not lose fault message.

2, analysis filterbank can be designed to special different-bandwidth bank of filters analysis of failure transient signal, and the high more subband bandwidth of frequency is wide more, solved fault transient signal intermediate frequency rate more high-load more a little less than, the difficult problem of difficult more detection.

3, except that the low frequency arrowband section that contains the power frequency amount; The criterion structure has adopted a plurality of subband high-frequency signals that cover the overall height frequency range; Can change each sub-bands of frequencies of self adaptation adjustment with sample frequency; Do not receive the influence of sample frequency, solved the difficult problem that traditional transient protection is difficult for confirming mid-band frequency to be analyzed.

4, the single-ended transient signal high fdrequency component of the transmission line treating capacity differential protecting method of the present invention's proposition; The difference of utilizing the inside and outside both sides of bus transient high frequency component treating capacity is through majority voting mechanism structure criterion; Realized that district's internal and external fault accurately differentiates; Can not judge by accident, reliability is high, can the protection circuit total length.

5, the present invention protects and adopts the harmless Transient High Frequency Signal of cutting apart of complete restructuring analysis bank of filters; Make corresponding relevant treatment respectively; Comprehensively judge; On hardware, realize redundant reserve configuration, reach fault-tolerant resist technology from basic principle and hardware implementation mode like this, help further improving fault-tolerance, anti-interference, the reliability of this guard method.

6, the single-ended transient signal high fdrequency component of the transmission line treating capacity differential protecting method that proposes of the present invention, the institute with transient protection has superiority, and to bus distributed capacitance size require lowly, general circuit bus can both meet the demands.

7, bank of filters adopts parallel construction, and real-time is good, and the whole algorithm amount of calculation is little, helps the protection of Project Realization ultrahigh speed.

Description of drawings

Fig. 1 (a) is that supertension line adopts the transient current amount to handle, and realizes the network system sketch map of single-ended transient signal high fdrequency component treating capacity differential protection.

Fig. 1 (b) is that supertension line adopts the transient voltage amount to handle, and realizes the network system sketch map of single-ended transient signal high fdrequency component treating capacity differential protection.

Embodiment

A kind of with in the transient high frequency component treating capacity---it is example that the transient high frequency of fault current is divided energy and the complete reconstruct different-bandwidth bank of filters with three hf channels below; In conjunction with embodiment and accompanying drawing the present invention is described in further detail, but execution mode of the present invention is not limited thereto.

Embodiment

Shown in Figure 1 is 500kV extra high voltage network model.In this model, M terminal shortcircuit capacity is that 8GVA, W terminal shortcircuit capacity are 5GVA, and circuit MN is long for 120km, circuit NW length are 200km, and each bus direct-to-ground capacitance is 6000PF.To extra high voltage network shown in Figure 1, single-ended transient signal high fdrequency component treating capacity differential protecting method comprises the steps:

The first step: outer, the interior both sides transient current I of collection bus M ₁, I ₂, utilize complete reconstruct different-bandwidth analysis filterbank with transient current I ₁And I ₂HFS be divided into three high fdrequency component I _1hf1, I _1hf2, I _1hf3And I _2hf1, I _2hf2, I _2hf3(this instance sample frequency is got 200kHz, and three hf channel frequencies are respectively 12.5kHz～25kHz, 25kHz～50kHz, 50kHz～100kHz).

Second step: the transient high frequency of calculating each passage is divided energy P_I _1hf1, P_I _1hf2, P_I _1hf3And P_I _2hf1, P_I _2hf2, P_I _2hf3If, P_I _1hf1＞P _Sqd1Or P_I _2hf1＞P _Sqd2, i.e. P _S=((P_I _1hf1＞P _Sqd1)+(P_I _2hf1＞P _Sqd2))=1 o'clock, the expression line failure then starts protection.

The 3rd step: energy difference (always deducting the amount in the outside) diff that calculates M bus inboard and each passage transient high frequency electric current of the outside with inboard amount ₁=P_I _2hf1-P_I _1hf1, diff ₂=P_I _2hf2-P_I _1hf2, diff ₃=P_I _2hf3-P_I _1hf3Employing majority voting mechanism is if the energy difference of 3 passages has 2 greater than setting value (this value is 0 in theory, and for leaving certain nargin, adjusting is suitable arithmetic number), if promptly satisfy Act=((diff ₁＞k _Set1)+(diff ₂＞k _Set2)) ((diff ₂＞k _Sset2)+(diff ₃＞k _Set3)) ((diff ₁＞k _Set1)+(diff ₃＞k _Set3))=1, then, be judged as troubles inside the sample space.Otherwise, be judged as external area error.K wherein _Set1, k _Set2, k _Set3For circuit M holds the differential setting value of single-ended each passage of transient signal high fdrequency component treating capacity differential protecting method, be arithmetic number.P_I _1hf1, P_I _1hf2, P_I _1hf3Try to achieve by following formula:

$\left\{\begin{array}{c}P\_{\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="HSA00000693832800011.png"\; state="\{\{state\}\}">I</figure-callout>}}_{1\mathrm{<figure-callout\; id="1"\; label="Hf"\; filenames="HSA00000693832800011.png"\; state="\{\{state\}\}">Hf</figure-callout>}1}=\underset{j=1}{\overset{\mathrm{<figure-callout\; id="1"\; label="n\; I"\; filenames="HSA00000693832800011.png"\; state="\{\{state\}\}">n</figure-callout>}}{\mathrm{\&Sigma;}}}{I}_{}{}_{1\mathrm{Hf}1j}\\ P\_{\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="HSA00000693832800011.png"\; state="\{\{state\}\}">I</figure-callout>}}_{1\mathrm{<figure-callout\; id="2"\; label="Hf"\; filenames="HSA00000693832800011.png"\; state="\{\{state\}\}">Hf</figure-callout>}2}=\underset{j=1}{\overset{\mathrm{<figure-callout\; id="1"\; label="n\; I"\; filenames="HSA00000693832800011.png"\; state="\{\{state\}\}">n</figure-callout>}}{\mathrm{\&Sigma;}}}{I}_{}{}_{1\mathrm{Hf}2j}\\ P\_{\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="HSA00000693832800011.png"\; state="\{\{state\}\}">I</figure-callout>}}_{1\mathrm{Hf}3}=\underset{j=1}{\overset{n}{\mathrm{\&Sigma;}}}{I}_{1\mathrm{Hf}3j}\end{array}\right.;$ N gets 200.

In the above-mentioned criterion construction process, k _Set1, k _Set2, k _Set3Be respectively the setting value of single-ended transient signal high fdrequency component treating capacity differential protecting method, and be arithmetic number.When specifically adjusting, can real system be the basis, adjust in conjunction with certain nargin.

The foregoing description is a typical embodiment of the present invention; But execution mode of the present invention is not limited by the examples; Other is any not to deviate from change, the modification done under spirit of the present invention and the principle, substitute, combination, simplify the technical scheme that is obtained; All should be the substitute mode of equivalence, be included within protection scope of the present invention.

Claims (9)

1. the single-ended transient signal high fdrequency component of the transmission line of novel practical treating capacity differential protecting method; After it is characterized in that gathering the inside and outside both sides of bus transient currents (or transient voltage), utilize complete restructuring analysis bank of filters with transient current (or voltage) signal lossless be divided into a low frequency sub-band component and a plurality of high-frequency sub-band component; Then; Calculate respectively the inside and outside both sides of bus corresponding transient high frequency subband component energy difference or entropy is poor or the poor or unusual degree of complexity is poor or modulus maximum is poor; Or other difference; Through majority voting mechanism, judgement is in the district, or external area error by a plurality of passage differences of bank of filters.The following step of concrete employing:

(1) gathers outer, the interior both sides transient current I of protection installation place bus ₁, I ₂(or voltage U ₁, U ₂), utilize complete restructuring analysis bank of filters that it nondestructively is divided into a low frequency sub-band component U respectively _1LfWith a plurality of high-frequency sub-band component U _1hf1, I _1hf2, I _1hf3... I _2Lf(or voltage U _1LfAnd U _1hf1, U _1hf2, U _1hf3...).

(2) energy or entropy or complexity or unusual degree or modulus maximum or other of asking for each high-frequency sub-band component are handled value P_I _1hf1, P_I _1hf2, P_I _1hf3... (or P_U _1hf1, P_U _1hf2, P_U _1hf3...), calculate then the inside and outside both sides of bus transient currents (or voltage) respective channel the high-frequency sub-band component energy difference or entropy is poor or the poor or unusual degree of signal complexity is poor or modulus maximum is poor or other difference diff ₁, diff ₂, diff ₃... (these differences always deduct the Transient Signal Processing amount of outside respective channel and obtain) by the inboard Transient Signal Processing amount of bus.

(3) these differences of being calculated by (2) judge it is troubles inside the sample space or external area error through majority voting mechanism.Because the transient high frequency component of fault-signal constantly reflects on the line, reflects; Very fast in protection installation place detected transient high frequency amount polarity and magnitude, thus the correct detection of transient state amount judge must be in transient signal completion before ripple arrives for the second time at once.For rapidity and the reliability that guarantees that the transient state amount detects, specially formulate a majority voting mechanism, i.e. the difference diff of each passage ₁, diff ₂, diff ₃... with setting value relatively, the great majority in them are judged as certain regional fault and promptly confirm as this zone fault, and difference that needn't all passages relatively draws consistent conclusion with setting value, just comes to a conclusion.With the system that has only 3 hf channels is example, when satisfying P _S=((| P_I _1hf1|＞P _Sqd1)+(| P_I _2hf1|＞P _Sqd2))=1 o'clock, the expression line failure then starts protection; Further, if diff ₁, diff ₂, diff ₃There are 2 greater than its setting value in these 3 differences, i.e. Act=((diff ₁＞k _Set1)+(diff ₂＞k _Set2)) ((diff ₂＞k _Set2)+(diff ₃＞k _Set3)) ((diff ₁＞k _Set1)+diff ₃＞k _Set3))=1 o'clock, then, be judged as troubles inside the sample space; Otherwise, be judged to the external area error of this protective device.P wherein _Sqd1, P _Sqd2Be protection startup value, k _Set1, k _Set2, k _Set3For this protects the setting value of differential action, these values all are 0 in theory, but in order to make the protection action have certain nargin, adjusting is suitable arithmetic number.

2. the single-ended transient signal high fdrequency component of transmission line according to claim 1 treating capacity differential protecting method; It is characterized in that: step (2) is said collect the inside and outside both sides of bus transient currents (or voltage) signal after; Utilize complete restructuring analysis bank of filters that transient current (or voltage) signal lossless is divided into a low frequency sub-band component and a plurality of high-frequency sub-band component; Calculate the energy difference of the inside and outside both sides of bus respective channel transient high frequency component or entropy is poor or the poor or unusual degree of complexity is poor or modulus maximum is poor or other difference, the difference computational methods are specific as follows:

Diff ₁=P_I _2hf1-P_I _1hf1, diff ₂=P_I _2hf2-P_I _1hf2, diff ₃=P_I _2hf3-P_I _1hf3... (or diff ₁=P_U _2hf1-P_U _1hf1, diff ₂=P_U _2hf2-P_U _1hf2, diff ₃=P_U _2hf3-P_U _1hf3...).I wherein _1hf1, I _1hf2, I _1hf3... I _2hf1, I _2hf2, I _2hf3... be I ₁, I ₂(U _1hf1, U _1hf2, U _1hf3... U _2hf1, U _2hf2, U _2hf3... be U ₁, U ₂) in the transient high frequency component of each passage.P_I _1hf1, P_I _1hf2, P_I _1hf3... P_I _2hf1, P_I _2hf2, P_I _2hf3... (or P_U _1hf1, P_U _1hf2, P_U _1hf3... P_U _2hf1, P_U _2hf2, P_U _2hf3...) energy or entropy or complexity or unusual degree or modulus maximum or other treating capacity of expression bus inside and outside both sides transient currents (or voltage) each passage high fdrequency component.Diff ₁, diff ₂, diff ₃... represent the poor of transient high frequency component treating capacity that the inside and outside both sides of the bus of each frequency band of circuit are corresponding respectively, poor or entropy is poor or signal complexity is poor or unusual degree is poor or modulus maximum is poor or other difference like energy.

3. according to the single-ended transient signal high fdrequency component of the said transmission line of claim 1 treating capacity differential protecting method, it is characterized in that: 1. this guard method adopts complete reconfigurable filter group that the fault transient signal is carried out lossless analysis, does not lose fault message.2. analysis filterbank can be designed to special different-bandwidth bank of filters analysis of failure transient signal, and the high more subband bandwidth of frequency is wide more, solved fault transient signal intermediate frequency rate more high-load more a little less than, the difficult problem of difficult more detection.3. except that the low frequency arrowband section that contains the power frequency amount; The criterion structure has adopted a plurality of subband high-frequency signals that cover the overall height frequency range; Can change each sub-bands of frequencies of self adaptation adjustment with sample frequency; Do not receive the influence of sample frequency, solved the difficult problem that traditional transient protection is difficult for confirming mid-band frequency to be analyzed.4. the institute of this protection algorithm with transient protection has superiority, and to bus distributed capacitance size require lowly, general circuit bus can both meet the demands.5. should protect accurately interior, the external area error of right area subregion of algorithm, can the protection circuit total length.6. bank of filters adopts parallel construction, and real-time is good, and the whole algorithm amount of calculation is little, helps the protection of Project Realization ultrahigh speed.

4. according to the single-ended transient signal high fdrequency component of the said transmission line of claim 1 treating capacity differential protecting method; Behind the transient current that collects the inside and outside both sides of bus, two ends (or voltage) signal; Utilize complete restructuring analysis bank of filters with transient current (or voltage) signal lossless be divided into a low frequency sub-band component and a plurality of high-frequency sub-band component; Each frequency range transient high frequency component is suitably handled, and poor, so judge be in the district, or external area error.On basic principle and hardware implementation mode, all reach fault-tolerant resist technology like this, with fault-tolerance, anti-interference, the reliability of further this guard method of raising.In some electric power system, this invention guard method also can be reduced to single pass pattern, and these are all at the row of patent protection of the present invention.

5. according to the single-ended transient signal high fdrequency component of the said transmission line of claim 1 treating capacity differential protecting method; Between bus and instrument transformer (current transformer or voltage transformer); Add trap or miscellaneous equipment, then ask for the difference of the inside and outside both sides of bus transient high frequency component treating capacity, utilize relevant difference establishing protective criterion again; Be the deformation process of guard method of the present invention, all drop on the row of the protection of patent of the present invention.

6. according to the single-ended transient signal high fdrequency component of the said transmission line of claim 1 treating capacity differential protecting method; The inventive method both had been applicable to the single-ended transient current high fdrequency component of transmission line treating capacity differential protecting method; Also be applicable to the single-ended transient voltage high fdrequency component of transmission line treating capacity differential protecting method, the single-ended transient protection differential based on the high fdrequency component treating capacity of transient current or transient voltage all drops on the row of the present invention's protection.

7. according to the single-ended transient signal high fdrequency component of the said transmission line of claim 1 treating capacity differential protecting method; Any based on the high fdrequency component of extracting the protected circuit two ends inside and outside both sides of bus transient currents (or voltage) earlier; Then the transient high frequency component is handled and obtained some processing value; Then poor to these processing values of the inside and outside both sides of bus, according to the difference establishing protective criterion of these transient high frequency component treating capacities, all be equivalence replacement and deformation process to the inventive method; Such as the energy that replaces asking the transient high frequency component in the hope of the absolute value of transient high frequency component; It is poor to remake afterwards, and structure is similarly protected criterion with the present invention, all at the row of patent protection of the present invention.

8. other does not anyly deviate from the change done under spirit of the present invention and the principle, modification, substitutes, combination, simplifies the technical scheme that is obtained, and all should be the substitute mode of equivalence, is included within protection scope of the present invention.

9. according to the single-ended transient signal high fdrequency component of the said transmission line of claim 1 treating capacity differential protecting method; Patented method of the present invention is equally applicable to protection of direct current supply line; In DC transmission system, use this method, drop on equally within the scope of patent protection of the present invention.

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