CN108923398A - A kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure - Google Patents
A kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure Download PDFInfo
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- CN108923398A CN108923398A CN201810810748.6A CN201810810748A CN108923398A CN 108923398 A CN108923398 A CN 108923398A CN 201810810748 A CN201810810748 A CN 201810810748A CN 108923398 A CN108923398 A CN 108923398A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/265—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured making use of travelling wave theory
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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Abstract
The invention discloses a kind of DC distribution network protection methods based on voltage characteristic traveling wave Similar measure.The transient voltage electric current at route both ends carries out high frequency sampling after DC Line Fault occurs for the present invention, is converted to the anti-traveling wave of line mode voltage of traveling wave and opposite side before the line mode voltage of protection zone side；Anti- traveling wave is in the polarity difference of external area error in area before causing traveling wave catadioptric and both ends based on fault point impedance mismatch, using a kind of similarity of both compatible Dynamic Matching Similar measure algorithm reflections of the adjacent diffusion of global optimum waveform, to carry out reliable recognition to troubles inside the sample space and external area error.The present invention can compensate for traveling wave delay and clock synchronization error, and not vulnerable to both ends sampling frequency deviation, shortage of data damage etc. influences, and fault-tolerance is higher, and detection speed is fast, so that DC distribution net powered operation is more reliable.
Description
Technical field
The invention belongs to flexible direct current field of distribution network, it is related to can recognize the quick protection of DC distribution net internal fault external fault
Scheme, especially a kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure.
Background technique
Building Multi-port direct-current distribution system using two level VSC of tradition or modularization multi-level converter (MMC) can be real
The flexible modulation and distribution of existing power, are conducive to effective consumption of distribution power, therefore receive the extensive concern of experts and scholars.
But since correlative study is still in starting stage, direct current system topological structure, converter structure and control strategy, system earth mode
Etc. having no unified standard, DC Line Fault characteristic also difference affected by many factors.And DC Line Fault generates biggish failure
Electric current can jeopardize converter safety, and the relaying configuration that the raising that quick-action protection requires even more increases direct-flow distribution system is difficult
Degree.
Non-unit protection lacks selectivity for the direct current distribution of complex topology structure, and setting value order is complicated；Distance protection
Can not protection circuit overall length, and because distribution network line is shorter, so that calculated result is influenced vulnerable to measurement error and transition resistance；Electricity
Stream differential protection can satisfy selective requirement, there is good performance under different faults levels of current.But due to direct current system
Unite interpolar failure high current change rate di/dt, proposes high requirement to the accurate clock synchronization of both ends measurement electric current, meets quick-action
The case where being likely to occur external area error malfunction simultaneously, or when monopole failure occurs due to MMC or big resistance inverter direct current system
Fault current variation is smaller, influences fault detection, then influences the reliable power supply of distribution.
Summary of the invention
The technical problem to be solved by the present invention is to overcome the problems of the above-mentioned prior art, a kind of reliable recognition is provided
The fast-speed direct current distribution protection method of external area error in area, this method utilize the transmission characteristic of traveling wave, are based on protection zone one
Before the line mode voltage at end traveling wave with to the anti-traveling wave of side line mode voltage, in troubles inside the sample space, wave-form similarity is low, external area error when waveform
The high feature of similarity quickly determines abort situation.
In order to solve the above technical problems, the technical solution adopted by the present invention is as follows：One kind is similar based on voltage characteristic traveling wave
The DC distribution network protection method estimated comprising following steps：
S1, using two kinds of start-up criterions of one-terminal current mutation rate and unbalance voltage, both meet first, then quick start
The protection of feature traveling wave Similar measure carries out the identification of area Nei Yu area's external position；
After S2, protection starting, high-frequency sampling is carried out to DC line positive and negative anodes voltage and current, obtains adopting for 4 groups of a length of l
Sampling point collection, phase-model transformation obtain line mode voltage and electric current, and calculate traveling wave and line mould electricity before acquisition line mode voltage on this basis
Press anti-traveling wave；
S3, traveling wave U before the line mode voltage of protection zone one end is obtained through communicationqWith the anti-traveling wave U of line mode voltage of opposite endf, take
UqIn continuous s point (s<L, l are voltage and current high frequency sampling number), template U is used as after standardization* q, choose equal length
U is obtained by translation and standardization for the data window of sfL-s+1 subset U* f(m), m=1,2 ... l-s+1；
S4, anti-traveling wave subset U is successively calculated using optimization algorithm* f(m)With template U* qThe compatible Dynamic Matching of adjacent diffusion
Cost function optimal solution obtains multiple subset Similar measure result Cop(m)；
S5, C is obtained by comparingop(m)In minimum value Cop_min(i.e. global optimum's Similar measure result), and and threshold value
Cop_setCompare, be higher than threshold value, then it is assumed that troubles inside the sample space occurs, otherwise it is assumed that external area error occurs；
If external area error S6, occurs, involution is protected；If troubles inside the sample space occurs, according to selecting pole criterion to determine failure classes
Type, then protection act carries out Fault Isolation.
The present invention uses a kind of phase of both compatible Dynamic Matching Similar measure algorithm descriptions of adjacent diffusion of global optimum
Like degree, remain the temporal aspect of traveling-wave waveform, compensate for the time delay of traveling wave and communication process, and to shortage of data,
Damage has certain tolerance.
Based on the above technical solution, the present invention can also be improved as follows.
Further, in step S1, starting protection criterion is specifically included：
Consider the electrical characteristic of different DC Line Faults under DC distribution net difference converter structure and earthing mode, direct current
When network short circuit fault, since capacitor instantaneous discharge makes electric current uprush, current-rising-rate starting protection can be used；And MMC and
It is single electrical merely with current-rising-rate since curent change is relatively slow when monopolar grounding fault occurs for big resistance eutral grounding inverter
Amount, which may cause protection, reliably to be started, and unbalance voltage starting protection can be added, and protect reliable quick start to realize, tool
Body start-up criterion is as follows：
Or | Up+Un| > UsetA,
Wherein, I is protection section two sides positive and negative anodes DC current values；Up、UnRespectively DC line positive electrode and negative electrode electricity
Pressure；ΔIset、UsetARespectively DC current climbing protection starting threshold value and DC voltage unbalance protection start threshold
Value.
Beneficial effect using above-mentioned further scheme is：For different types of direct current distribution line fault, by list
It holds electrical quantity protection quick start to protect based on the region recognition of feature traveling wave Similar measure, avoids the detection of Similar measure algorithm
The requirement that failure samples high-frequency, communication is continued working with processing equipment, while also avoiding failure and Similar measure occurs
The adjusting of threshold value, and be the sampling time needed for reaching the threshold value.
Further, in step S2, the phase-model transformation of DC voltage and current is specifically included：
Since direct-flow distribution system realizes electric energy transmission and symmetrical configuration by two polar curves, thus use
Karrenbauer transformation carries out voltage and current phase-model transformation, and obtains line mode voltage and electric current according to the following formula：
Wherein, Ux、IxFor line mode voltage and electric current；Ip、InFor DC line positive electrode and negative electrode electric current.
Beneficial effect using above-mentioned further scheme is：Due in traveling wave transmission process, the propagation of line mould and ground mould
Speed and frequency dependence, the frequency characteristic of middle line mould is more uniformly and high band decaying is smaller, is thus mentioned using phase-model transformation
The deformation during traveling wave can be effectively reduced in line taking line wave, improves the reliability of protection.
Further, it in step S2, is based on line mode voltage and electric current obtains traveling wave and the anti-traveling wave of line mode voltage before line mode voltage,
It specifically includes：
Line direction is positive by protection direction DC line before defining route traveling wave, calculates traveling wave before obtaining voltage according to the following formula
With the anti-traveling wave of voltage：
Wherein, Uq、UfTraveling wave and the anti-traveling wave of line mode voltage respectively before line mode voltage；ZxFor route line mould impedance value.
Beneficial effect using above-mentioned further scheme is：For traditional current differential protection, due to DC Line Fault
Current changing rate is very high, small time difference, and time irreversibility will also result in very big error, and be based on the positive anti-waveform of voltage
Similitude can effectively improve the reliability of protection using its integral position and shape information.
Further, in step S3, template U is obtained by the positive and negative traveling wave of line mode voltage* qWith anti-traveling wave subset U* f(m), specific to wrap
It includes：
Voltage magnitude (ordinate) is subjected to perunit processing, i.e.,：
Wherein, U* q_y、U* f(m)_yFor template U* qWith each subset U of anti-traveling wave* f(m)Ordinate collection；UqsFor UqMiddle taken length
For the contact potential series of s；Uf(m)For UfIn m-th of length be all s contact potential series, m=1,2 ... l-s+1；UNFor direct current distribution volume
Constant voltage；
And time shaft linear transformation to [0, c] section is obtained into abscissa collection U* q_x、U* f(m)_x, wherein c is that neighborhood deviates generation
Valence, the abscissa difference between consecutive points is 1/ (c-1) at this time, then has U* q={ (U* q_x(i),U* q_y(i)) | i=1,2 ... s },
U* f(m)={ (U* f(m)_x(i),U* f(m)_y(i)) | i=1,2 ... s }.
Beneficial effect using above-mentioned further scheme is：Solve line mode voltage traveling wave point set dimension mismatch problem,
And cost c adjustment improvement matching properties can be deviateed by neighborhood.
Further, in step S4, based on the cost function of the compatible Dynamic Matching Similar measure of adjacent diffusion, it is specifically included
Expression formula：
Wherein, U* qAnd U* f(m)Traveling wave template and the anti-row of line mode voltage before the line mode voltage obtained after respectively normalized
M-th of subset of wave；C(m)For U* qAnd U* f(m)Between the compatible Dynamic Matching cost of adjacent diffusion, subset can be obtained most in optimized algorithm
Excellent cost Cop(m), value is smaller to illustrate that the two is more similar；α (k), β (k) are nondecreasing sequence, can be considered { 1,2 ... s } × { 1,2 ...
S } at certain of space it is non-subtract path, to characterize the order of Point set matching；For based on n1The compatible coefficient of point
n2Vertex neighborhood Weighted distance (n1≥n2), withFor, expression formula is：
Wherein, ω is compatible coefficient, for characterizing sequence point in the compatibility put up and down；KdivLetter is evaluated to deviate
Number, when input variable is more than a certain threshold kdiv_set, then functional value is a positive value Kdiv_const, otherwise it is zero；‖ ‖ is point-to-point transmission
Euclidean distance；Sqn、SfnAnti- traveling wave is in input point adjacent n orderly point set indexes before respectively, for former boundary of point set
Point progress is unilateral to be taken a little, otherwise bilateral to take a little；For U* qInterior certain point n1The longitudinal axis average value of a neighborhood point,Also same.
Further, in step S4, the optimization algorithm of the optimal Similar measure cost function of subset is obtained, is specifically included：
Subset cost function optimal solution can be realized by dynamic programming algorithm.Positive and negative traveling wave of middle line mode voltage is discrete has for its
Sequence point set { U* q(1),U* q(2),…,U* qAnd { U (s) }* f(m)(1),U* f(m)(2),…,U* f(m)(s) } corresponding dull pairing (U* q
(α(k)),U* f(m)(β (k))) meet α (1)=β (1)=1, α (n)=β (n)=s, and all k=1 ..., n-1 are all satisfied α
(k+1)=α (k) or α (k)+1, β (k+1)=β (k) or β (k)+1.
Beneficial effect using above-mentioned further scheme is：A kind of adjacent diffusion phase of global optimum is proposed using the present invention
Hold Dynamic Matching Similar measure algorithm, in the similitude of description traveling-wave waveform, retains compared to common Hausdorff distance
The timing of traveling wave, can more embody the otherness between orderly point set.It is more embodied compared with general Minkowski is equidistant
The position of waveform and shape difference.Algorithm is improved to shortage of data, damage by introducing deviation evaluation function and compatible coefficient
Tolerance, and translate the optimal distance cost that data window obtains between more subsets and template and be minimized and can solve clock synchronization not
Stationary problem.
Further, in step S6, troubles inside the sample space progress failure occurs and selects pole, specifically include DC Line Fault selects pole criterion：
Wherein, UsetBTo select pole threshold value based on the unbalanced failure of DC voltage.
The device have the advantages that as follows：The present invention can quickly detect and identify in DC line area and external area error
And fault type, furthermore the compatible Dynamic Matching Similar measure algorithm of global optimum's adjacent diffusion based on voltage characteristic traveling wave makes
Obtaining fault zone positioning is not influenced by traveling wave and signal delay, has higher support to the loss and damage problem of signal yet
Resistance compensates for single-end electrical protective seletion and the insufficient defect of differential protection quick-action.
Detailed description of the invention
Fig. 1 is four end 10kV DC distribution network simulation model schematics of the embodiment of the present invention；
Fig. 2 is the match condition and C of monopole failure optimal subset and template in area of the embodiment of the present inventionop_minCalculated result
Figure；
Fig. 3 is the match condition and C of monopole failure optimal subset and template outside area of the embodiment of the present inventionop_minCalculated result
Figure；
Fig. 4 is monopole failure unbalance voltage waveform diagram of the embodiment of the present invention；
Fig. 5 is DC distribution network protection method flow chart of the embodiment of the present invention.
Specific embodiment
The present invention will be further described in detail with specific embodiment with reference to the accompanying drawings of the specification.
Fig. 1 is the four end VSC DC distribution network simulation model schematics based on PSCAD emulation platform building.Wherein four end
Exchange side voltage class is 35kV, equivalent 5 Ω of forward-sequence reactance, 80 ° of positive sequence impedance angle；DC voltage is ± 10kV, using frame
Ceases to be busy model, wire length are as shown in the figure.
Embodiment
Flow chart is to DC line L according to Fig.5,12Protection discuss.
S1, the electrical characteristic for considering different DC Line Faults under DC distribution net difference converter structure and earthing mode, root
According to following criterion starting protection：
Or | Up+Un| > UsetA,
Wherein, I is protection section two sides positive and negative anodes DC current values；Up、UnRespectively DC line positive electrode and negative electrode electricity
Pressure；ΔIset、UsetARespectively DC current climbing protection starting threshold value and DC voltage unbalance protection start threshold
Value.
100 Ω plus earth failures are set, according to unbalance voltage starting protection.For guarantee direct current protecting quick-action,
It can be by UsetASetting is smaller, even if DC Line Fault does not occur, due to similarity degree height, outside area's inner region based on traveling wave Similar measure
Recognizer can be determined as external area error to enable protection involution.U is taken in emulationsetA=10%UN。
After S2, protection starting, high-frequency sampling is carried out to DC line positive and negative anodes voltage and current, obtains adopting for 4 groups of a length of l
Sampling point collection, and line mode voltage and electric current are obtained according to the following formula：
Wherein, Ux、IxFor line mode voltage and electric current；Ip、InFor DC line positive electrode and negative electrode electric current.
Traveling wave and the anti-traveling wave of voltage before obtaining voltage are calculated according to the following formula：
Wherein, Uq、UfTraveling wave and the anti-traveling wave of line mode voltage respectively before line mode voltage；ZxFor route line mould impedance value.
Since distribution network line is short, higher sample rate is needed to capture traveling-wave waveform effective information, and the selection of l length
Fully demonstrating for operating time of protection and feature traveling-wave waveform should then be comprehensively considered.In this example, sample frequency is set in emulation
It is set to 200kHz, l is taken as 40, and utilizes the line of traveling wave (direction direction opposite side) before the line mode voltage of protection 12_1 and protection 12_2
The anti-traveling wave of mode voltage (being directed toward this side in direction) carries out waveform Similar measure.
S3, communication obtain traveling wave U before the line mode voltage of protection 12_1qWith the anti-traveling wave U of line mode voltage of 12_2f.Take UqMiddle company
Template U is used as after continuous the 6th~30 point standardization* q.The data window of equal length s=25 is chosen through translation and standardization
Obtain UfSeveral subset U* f(m), wherein neighborhood deviates cost c=1.
S4, anti-traveling wave subset U is successively calculated using dynamic programming algorithm* f(m)With template U* qThe compatible dynamic of adjacent diffusion
Matching cost Function Optimization solution obtains multiple subset Similar measure result Cop(m).In this example, for cost function：
Wherein, deviate evaluation function KdivIn threshold kdiv_setIt is determined as 3.5, deviates constant Kdiv_constIt is taken as 10；Take n1
=5 points do deviation assessment, and take n2It is distance weighted that=3 points do compatible coefficient.
S5, C is obtained by comparingop(m)In minimum value Cop_min(i.e. global optimum's Similar measure result), and and threshold value
Cop_setCompare, be higher than threshold value, then it is assumed that troubles inside the sample space occurs, otherwise it is assumed that external area error occurs；
In this example, Cop_setAccording to the critical distance when a variety of transition resistances of setting, abort situation, fault type
And obtained multiplied by safety factor, it is taken as 0.8.In area when monopole failure optimal subset and template match condition and Cop_minIt calculates
As a result as shown in Fig. 2, as can be seen from the results, the similarity degree of the two is not high, Cop_minReach 2.4473, has been greater than Cop_set, thus
It is determined as troubles inside the sample space；Outside area when monopole failure optimal subset and template match condition and Cop_minCalculated result such as Fig. 3 institute
Show, the two essentially coincides, Cop_minOnly 0.0797, it is less than Cop_set, thus it is determined as external area error.
If external area error S6, occurs, involution is protected；If troubles inside the sample space occurs, pole criterion is selected to determine according to following
Fault type, then protection act carries out Fault Isolation：
In this example, pole threshold value U is selected based on the unbalanced failure of DC voltagesetB=30%UN, according to Fig.4, not
Balanced voltage waveform and UsetBSize relation, DC line plus earth is determined, it is possible thereby to realize the accurate of DC Line Fault
Select pole.The present embodiment demonstrates the correctness and feasibility of the proposed direct current distribution protection scheme of the present invention.
Claims (8)
1. a kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure, which is characterized in that including following step
Suddenly：
S1, using two kinds of start-up criterions of one-terminal current mutation rate and unbalance voltage, both meet first, then quick-start feature
The protection of traveling wave Similar measure carries out the identification of area Nei Yu area's external position；
After S2, protection starting, high-frequency sampling is carried out to DC line positive and negative anodes voltage and current, obtains the sampled point of 4 groups of a length of l
Collection, phase-model transformation obtain line mode voltage and electric current, and traveling wave and line mode voltage are anti-before calculating acquisition line mode voltage on this basis
Traveling wave；
S3, traveling wave U before the line mode voltage of protection zone one end is obtained through communicationqWith the anti-traveling wave U of line mode voltage of opposite endf, take UqIn
Continuous s point, s<L, l are voltage and current high frequency sampling number, and template U is used as after standardization* q, choosing equal length is s's
Data window obtains U by translation and standardizationfL-s+1 subset U* f(m), m=1,2 ... l-s+1；
S4, anti-traveling wave subset U is successively calculated using optimization algorithm* f(m)With template U* qThe compatible Dynamic Matching cost letter of adjacent diffusion
Number optimal solution, obtains multiple subset Similar measure result Cop(m)；
S5, C is obtained by comparingop(m)In minimum value Cop_min, i.e., global optimum's Similar measure as a result, and with threshold value Cop_set
Compare, be higher than threshold value, then it is assumed that troubles inside the sample space occurs, otherwise it is assumed that external area error occurs；
If external area error S6, occurs, involution is protected；If troubles inside the sample space occurs, according to selecting pole criterion to determine fault type, after
And protection act carries out Fault Isolation.
2. a kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure according to claim 1,
It is characterized in that, in step S1, starting protection criterion includes：
Consider the electrical characteristic of different DC Line Faults under DC distribution net difference converter structure and earthing mode, DC grid is short
When the failure of road, since capacitor instantaneous discharge makes electric current uprush, using current-rising-rate starting protection；And MMC and big resistance
When being grounded inverter generation monopolar grounding fault, since curent change is relatively slow, cause merely with the single electrical quantity of current-rising-rate
When protection can not reliably start, unbalance voltage starting protection is added, protects reliable quick start, specific start-up criterion to realize
It is as follows：
Or | Up+Un| > UsetA,
Wherein, I is protection section two sides positive and negative anodes DC current values；Up、UnRespectively DC line positive electrode and negative electrode voltage；Δ
Iset、UsetARespectively DC current climbing protection starting threshold value and DC voltage unbalance protection start threshold value.
3. a kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure according to claim 1,
It is characterized in that, in step S2, the phase-model transformation of DC voltage and current is specifically included：
Since direct-flow distribution system realizes electric energy transmission and symmetrical configuration by two polar curves, thus become using Karrenbauer
Swap-in row voltage and current phase-model transformation, and line mode voltage and electric current are obtained according to the following formula：
Wherein, Ux、IxFor line mode voltage and electric current；Ip、InFor DC line positive electrode and negative electrode electric current.
4. a kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure according to claim 1,
It is characterized in that, it is specific to wrap based on traveling wave and the anti-traveling wave of line mode voltage before line mode voltage and electric current acquisition line mode voltage in step S2
It includes：
Line direction is positive by protection direction DC line before defining route traveling wave, calculates traveling wave and electricity before obtaining voltage according to the following formula
Press anti-traveling wave：
Wherein, Uq、UfTraveling wave and the anti-traveling wave of line mode voltage respectively before line mode voltage；ZxFor route line mould impedance value；Ux、IxFor line
Mode voltage and electric current.
5. a kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure according to claim 1,
It is characterized in that, in step S3, template U is obtained by the positive and negative traveling wave of line mode voltage* qWith anti-traveling wave subset U* f(m), specifically include：
To solve line mode voltage traveling wave point set dimension mismatch problem, the voltage magnitude as ordinate is subjected to perunit processing,
I.e.：
Wherein, U* q_y、U* f(m)_yFor template U* qWith each subset U of anti-traveling wave* f(m)Ordinate collection；UqsFor UqMiddle taken length is s
Contact potential series；Uf(m)For UfIn m-th of length be all s contact potential series, m=1,2 ... l-s+1；UNFor the specified electricity of direct current distribution
Pressure；
And time shaft linear transformation to [0, c] section is obtained into abscissa collection U* q_x、U* f(m)_x, wherein c is that neighborhood deviates cost,
The abscissa difference between consecutive points is 1/ (c-1) at this time, then has U* q={ (U* q_x(i),U* q_y(i)) | i=1,2 ... s }, U* f(m)
={ (U* f(m)_x(i),U* f(m)_y(i)) | i=1,2 ... s }.
6. a kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure according to claim 5,
It is characterized in that, in step S4, based on the cost function of the compatible Dynamic Matching Similar measure of adjacent diffusion, specifically includes its expression
Formula：
Wherein, U* qAnd U* f(m)Traveling wave template and the anti-traveling wave m of line mode voltage before the line mode voltage obtained after respectively normalized
A subset；C(m)For U* qAnd U* f(m)Between the compatible Dynamic Matching cost of adjacent diffusion, optimized algorithm obtains subset optimal cost
Cop(m), value is smaller to illustrate that the two is more similar；α (k), β (k) are nondecreasing sequence, are considered as { 1,2 ... s } × { 1,2 ... s } into sky
Between certain it is non-subtract path, to characterize the order of Point set matching；For based on n1The n of the compatible coefficient of point2Vertex neighborhood
Weighted distance, n1≥n2, withFor, expression formula is：
Wherein, ω is compatible coefficient, for characterizing sequence point in the compatibility put up and down；KdivTo deviate evaluation function, when
Input variable is more than a certain threshold kdiv_set, then functional value is a positive value Kdiv_const, otherwise it is zero；‖ ‖ is that the Europe of point-to-point transmission is several
In distance；Sqn、SfnAnti- traveling wave clicks through origin collection boundary in input point adjacent n orderly point set indexes before respectively
Row is unilateral to be taken a little, otherwise bilateral to take a little；For U* qInterior certain point n1The longitudinal axis average value of a neighborhood point,Also
Together.
7. a kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure according to claim 1,
It is characterized in that, in step S4, obtains the optimization algorithm of the optimal Similar measure cost function of subset, specifically include：
Subset cost function optimal solution passes through dynamic programming algorithm realization, the discrete orderly point set of the positive and negative traveling wave of middle line mode voltage
{U* q(1),U* q(2),…,U* qAnd { U (s) }* f(m)(1),U* f(m)(2),…,U* f(m)(s) } corresponding dull pairing (U* q(α
(k)),U* f(m)(β (k))) meet α (1)=β (1)=1, α (n)=β (n)=s, and all k=1 ..., n-1 are all satisfied α (k+
1)=α (k) or α (k)+1, β (k+1)=β (k) or β (k)+1.
8. a kind of DC distribution network protection method based on voltage characteristic traveling wave Similar measure according to claim 1,
It is characterized in that, in step S6, troubles inside the sample space progress failure occurs and selects pole, specifically include DC Line Fault selects pole criterion：
Wherein, UsetBTo select pole threshold value based on the unbalanced failure of DC voltage；Up、UnRespectively DC line anode and negative
Pole tension.
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