CN110187241A  A kind of determination method of the ground connection medium type of onephase earthing failure in electric distribution network  Google Patents
A kind of determination method of the ground connection medium type of onephase earthing failure in electric distribution network Download PDFInfo
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 CN110187241A CN110187241A CN201910557993.5A CN201910557993A CN110187241A CN 110187241 A CN110187241 A CN 110187241A CN 201910557993 A CN201910557993 A CN 201910557993A CN 110187241 A CN110187241 A CN 110187241A
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Classifications

 G—PHYSICS
 G01—MEASURING; TESTING
 G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
 G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
 G01R31/08—Locating faults in cables, transmission lines, or networks
 G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
 G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors

 G—PHYSICS
 G01—MEASURING; TESTING
 G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
 G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
 G01R31/08—Locating faults in cables, transmission lines, or networks
 G01R31/088—Aspects of digital computing
Abstract
This application provides a kind of determination methods of the ground connection medium type of onephase earthing failure in electric distribution network, it include: when singlephase earth fault occurs for power distribution network, according to the original time series of the zerosequence current of onephase earthing failure in electric distribution network phase, phase space reconfiguration is carried out to the waveform of the zerosequence current；Determine the optimum delay time of phase space reconstruction；The smallest embedding dimension number of the phase space reconstruction is determined according to the optimum delay time；The correlation dimension of the phase space reconstruction is determined according to the smallest embedding dimension number；The corresponding relationship of the correlation dimension and ground connection medium type that obtain according to the correlation dimension and in advance, determines the ground connection medium type of the singlephase earth fault.Solve the problems, such as that the determination method accuracy of the ground connection medium type of onephase earthing failure in electric distribution network in the prior art is lower.
Description
Technical field
This application involves the determination methods of power distribution network ground connection medium type, are specifically related to a kind of power distribution network singlephase earthing event
The determination method of the ground connection medium type of barrier.
Background technique
With the rapid development of the national economy, power grid construction scale is also increasing.Power distribution network is that one of power grid is important
Component part, there are many kinds of the failures of power distribution network, such as line fault, transformer fault and ground fault etc..Singlephase earthing
Failure is a seed type of distribution net work earthing fault.When singlephase earth fault occurs for power distribution network, due to ground connection medium type
Difference, the performance characteristic of ground fault will also have biggish difference.Therefore, the ground connection of onephase earthing failure in electric distribution network is situated between
The determination of matter type is particularly important for the judgement and exclusion of ground fault.
Zerosequence current is a kind of electricity for representative analysis significance that power distribution network occurs when singlephase earth fault occurs
Stream, the distortion degree of zerosequence current will depend on the nonlinear degree of ground connection medium, specifically, ground connection medium nonlinear degree
Bigger, the content of higher hamonic wave is more, and the distortion degree of zerosequence current is bigger.Therefore, to the zero of singlephase earth fault phase
Sequence electric current deployment analysis can recognize different types of ground connection medium.In a kind of method for judging distribution net work earthing fault,
By analyzing high resistance ground zerosequence current wave distortion concavity and convexity, to dry floor tile, wetland brick, wet sand, dry crushing stone,
Eight kinds of wet rubble, dry tire and wet tire media carry out identification, classification.
However, the smaller and various noise of the zerosequence current value scene very big with interference after ground fault occurs for power distribution network
Under, the concavity and convexity variation of zerosequence current waveform will be more violent, and the accuracy that will lead to the above method is lower.So providing one
The determination method of the ground connection medium of the more acurrate onephase earthing failure in electric distribution network of kind, becomes those skilled in the art's urgent need to resolve
Important technological problems.
Summary of the invention
It is existing to solve this application provides a kind of determination method of the ground connection medium type of onephase earthing failure in electric distribution network
The lower problem of the ground connection medium determining method accuracy of distribution net work earthing fault.
A kind of determination method of the ground connection medium type of onephase earthing failure in electric distribution network, comprising:
When power distribution network occur singlephase earth fault when, according to the zerosequence current of onephase earthing failure in electric distribution network phase it is original when
Between sequence, phase space reconfiguration is carried out to the waveform of the zerosequence current；
Determine the optimum delay time of phase space reconstruction；
The smallest embedding dimension number of the phase space reconstruction is determined according to the optimum delay time；
The correlation dimension of the phase space reconstruction is determined according to the smallest embedding dimension number；
The corresponding relationship of the correlation dimension and ground connection medium type that obtain according to the correlation dimension and in advance, determine described in
The ground connection medium type of singlephase earth fault.
Optionally, the optimum delay time of the determining phase space reconstruction, comprising:
According to state x each in the original time series x (t)_{i}Corresponding Probability p_{x}(x_{i}), the x is calculated according to the following formula
(t) comentropy H (x):
According to each state q in the time series q (t) after the original time series x (t) delay τ_{j}Corresponding probability
P_{q}(q_{j}), the comentropy H (q) of the q (t) is calculated according to the following formula:
According to each state x in the x (t) and q (t)_{i}And q_{j}Corresponding joint probability P_{xq}(x_{i},q_{j}), it calculates according to the following formula
Conditional entropy H (q  x) of the q (t) for x (t):
Wherein, H (x, q) is the q (t) for the combination entropy of the x (t), and the H (x, q) is according to the x (t) and q
(t) each state x in_{i}And q_{j}Corresponding joint probability P_{xq}(x_{i},q_{j}), it is calculated according to the following formula:
According to the I (q, x) obtained by the H (q) and the H (q  x), first local minizing point in I (q, x) is determined
Optimum delay time of the corresponding τ as the phase space reconstruction；
Wherein,
Optionally, the smallest embedding dimension number that the phase space reconstruction is determined according to optimum delay time, comprising:
According to the point Y of the phase space reconstruction_{u}(m), calculating matrix a (u, m) according to the following formula:
Wherein, m is the dimension of the phase space reconstruction, Y_{x(u,m)}It (m) is distance Y_{u}(m) nearest point, x (u, m) be greater than
1 and be less than or equal to Nm τ integer；
According to the following formula in calculating matrix a (u, m) all elements mean value E (m):
When the value of the dimension m is greater than m_{0}, and when the value of E (m) will not change, enable the smallest embedding dimension number mb=
m_{0}+1。
Optionally, the correlation dimension that the phase space reconstruction is determined according to smallest embedding dimension number, comprising:
According to the smallest embedding dimension number, the point Y (t) in the phase space reconstruction is determined:
Y (t)=y (t), y (t+ τ) ..., y [t+ (mb1) τ] }, t=1,2 ..., N (mb1) τ；
Any one point chosen in N number of point that the phase space reconstruction includes is as a reference point；
The N1 point in addition to reference point is calculated to the distance of the reference point, is determined small at a distance from the reference point
In given value r point be relating dot；
Accounting C of the number of the relating dot in all possible relating dot number N (N1) is calculated according to the following formula_{mb}
(r):
Wherein, Y (i), Y (j) are respectively the ith and jth element in the Y (t), and θ is Heaviside unit function；
According to the C_{mb}(r) with the relationship of the rCalculate the correlation dimension P.
Optionally, the calculating correlation dimension P includes:
LnC is made under the smallest embedding dimension number_{mb}(r)=lnr curve determines the uncalibrated visual servo section of the curve,
The uncalibrated visual servo section is linear segments or nearlinear section, and the uncalibrated visual servo section is fitted to a fitting a straight line, is calculated
The slope of the fitting a straight line, using the slope of the fitting a straight line as the correlation dimension P.
Optionally, as steps described below, it obtains correlation dimension in advance and is grounded the corresponding relationship of medium type, comprising:
The zerosequence current that the onephase earthing failure in electric distribution network phase of medium type is grounded known to every kind is measured respectively, it is described known
Be grounded medium type including at least wet soil, dry earth, wet sand, dry sand ground, wet cement, wet branch and water resistance；
According to the original time series of the zerosequence current, phase space reconfiguration is carried out to the waveform of the zerosequence current；
Determine the optimum delay time of phase space reconstruction；
The smallest embedding dimension number of the phase space reconstruction is determined according to the optimum delay time；
The correlation dimension P of the phase space reconstruction is determined according to the smallest embedding dimension number_{n}:
Wherein, L indicates r_{in}The total number of value, n indicate ground connection medium type coding, n=1,2,3,4,5,6,7 difference tables
With showing ground connection medium water resistance, wet cement, wet soil, wet sand, the coding of wet branch, dry earth and dry sand ground；
According to known ground connection medium type and the correlation dimension, obtains correlation dimension in advance and be grounded pair of medium type
It should be related to.
Optionally, the corresponding relationship of the correlation dimension and ground connection medium type, comprising:
Work as P_{1}< P < P_{2}, determine that the ground connection medium type is wet cement；
Work as P_{2}< P < P_{3}, determine the ground connection medium type for wet soil；
Work as P_{3}< P < P_{4}, determine the ground connection medium type for wet sand；
Work as P_{4}< P < P_{5}, determine that the ground connection medium type is wet branch；
Work as P_{5}< P < P_{6}, determine that the ground connection medium type is dry earth；
Work as P_{6}< P < P_{7}, determine that the ground connection medium type is dry sand ground；
As P < P_{1}, determine that the ground connection medium type is water resistance；
Wherein, P is that the corresponding zerosequence current of unknown ground connection medium passes through the correlation dimension being calculated.
Method provided by the present application, from the angle of the zerosequence current Wave data of singlephase earth fault phase, using phase
Space Reconstruction method analyzes the corresponding zerosequence current waveform of different ground connection media, according to the optimum delay time of phase space reconstruction
Correlation dimension is determined with smallest embedding dimension number, passes through correlation dimension and the correlation dimension and ground connection medium type that in advance obtain
Corresponding relationship, determine it is unknown ground connection medium type.Compare the prior art, and this method can more accurately determine singlephase
The ground connection medium type of ground fault.
Detailed description of the invention
In order to illustrate more clearly of the technical solution of the application, letter will be made to attached drawing needed in the embodiment below
Singly introduce, it should be apparent that, for those of ordinary skills, without any creative labor,
It is also possible to obtain other drawings based on these drawings.
The step of Fig. 1 is a kind of confirmation method of ground connection medium of onephase earthing failure in electric distribution network provided by the present application is illustrated
Figure；
Fig. 2 a be grounded medium be wet soil when delay time and mutual information function relation curve；
Fig. 2 b is the relation curve for being grounded delay time and mutual information function when medium is dry earth；
Fig. 2 c be grounded medium be wet sand when delay time and mutual information function relation curve；
Fig. 2 d is the relation curve for being grounded delay time and mutual information function when medium is dry sand ground；
Fig. 2 e be grounded medium be wet cement when delay time and mutual information function relation curve；
Fig. 2 f is the relation curve for being grounded delay time and mutual information function when medium is wet branch；
Fig. 2 g is the relation curve for being grounded delay time and mutual information function when medium is water resistance；
Fig. 3 a be ground connection medium be wet soil when smallest embedding dimension number under lnC_{mb}(r)=lnr curve graph；
Fig. 3 b is ground connection medium lnC under smallest embedding dimension number when being dry earth_{mb}(r)=lnr curve graph；
Fig. 3 c be ground connection medium be wet sand when smallest embedding dimension number under lnC_{mb}(r)=lnr curve graph；
Fig. 3 d is ground connection medium lnC under smallest embedding dimension number when being dry sand ground_{mb}(r)=lnr curve graph；
Fig. 3 e is ground connection medium lnC under smallest embedding dimension number when being wet cement_{mb}(r)=lnr curve graph；
Fig. 3 f is ground connection medium lnC under smallest embedding dimension number when being wet branch_{mb}(r)=lnr curve graph；
Fig. 3 g is ground connection medium lnC under smallest embedding dimension number when being water resistance_{mb}(r)=lnr curve graph.
Specific embodiment
Below in conjunction with the attached drawing in the embodiment of the present application, technical solutions in the embodiments of the present application carries out clear, complete
Site preparation description, it is clear that described embodiment is only a part of the embodiment of the application, instead of all the embodiments.
Based on the embodiment in the application, those of ordinary skill in the art are obtained without making creative work
Every other embodiment, shall fall in the protection scope of this application.
Singlephase earth fault is a seed type of distribution net work earthing fault.When singlephase earth fault occurs for power distribution network, by
In the difference of ground connection medium type, the performance characteristic of ground fault will also have biggish difference.Therefore, power distribution network is singlephase
The determination of the ground connection medium type of ground fault is particularly important for the judgement and exclusion of ground fault.
Zerosequence current is a kind of electricity for representative analysis significance that power distribution network occurs when singlephase earth fault occurs
Stream, the distortion degree of zerosequence current will depend on the nonlinear degree of ground connection medium, specifically, ground connection medium nonlinear degree
Bigger, the content of higher hamonic wave is more, and the distortion degree of zerosequence current is bigger.Therefore, to the zero of singlephase earth fault phase
Sequence electric current deployment analysis can recognize different types of ground connection medium.In a kind of method for judging distribution net work earthing fault,
By analyzing high resistance ground zerosequence current wave distortion concavity and convexity, to dry floor tile, wetland brick, wet sand, dry crushing stone,
Eight kinds of wet rubble, dry tire and wet tire media carry out identification, classification.However, the zero sequence electricity after ground fault occurs for power distribution network
Under the smaller and various noise of the flow valuve scene very big with interference, the concavity and convexity variation of zerosequence current waveform will be more violent, meeting
Cause the accuracy of the above method lower.
In view of this, this application provides a kind of determination methods of the ground connection medium of onephase earthing failure in electric distribution network, with solution
The lower problem of the ground connection medium determining method accuracy of certainly existing distribution net work earthing fault.
Singlephase earthing refers to small electric current grounding system of distribution network singlephase earthing, is the most common failure of distribution system.Distribution
Zero sequence current mutual inductor is installed in the line facility of net, it is former when there is a phase electricity that ground connection occurs in the threephase electricity of distribution network line
When barrier, i.e., generation singlephase earth fault when, the phasor of threephase current and be not equal to zero, at this point, generated electric current in route
For zerosequence current.So zerosequence current caused by the different corresponding singlephase earth faults occurred of ground connection medium is because of medium
The difference of property and it is different.
As shown in FIG. 1, FIG. 1 is a kind of confirmation methods of the ground connection medium of onephase earthing failure in electric distribution network provided by the present application
Step schematic diagram, a kind of determination method of the ground connection medium of onephase earthing failure in electric distribution network includes the following steps:
S1: when singlephase earth fault occurs for power distribution network, according to the original of the zerosequence current of onephase earthing failure in electric distribution network phase
Beginning time series carries out phase space reconfiguration to the waveform of zerosequence current；
S2: the optimum delay time of phase space reconstruction is determined；
S3: the smallest embedding dimension number of phase space reconstruction is determined according to optimum delay time；
S4: the correlation dimension of phase space reconstruction is determined according to smallest embedding dimension number；
S5: the corresponding relationship of the correlation dimension and ground connection medium type that obtain according to correlation dimension and in advance determines singlephase
The ground connection medium type of ground fault.
Optionally, according to the original time series x (t) of the zerosequence current of onephase earthing failure in electric distribution network phase, to zero sequence electricity
The waveform of stream carries out phase space reconfiguration, and determines the delay time of phase space reconstruction, and specific steps include:
S11: according to state x each in original time series x (t)_{i}Corresponding Probability p_{x}(x_{i}), the x is calculated according to the following formula
(t) comentropy H (x):
S12: according to each state q in the time series q (t) after original time series x (t) delay τ_{j}Corresponding probability
P_{q}(q_{j}), the comentropy H (q) of the q (t) is calculated according to the following formula:
Wherein it is possible to understand, q (t)=x (t+ τ)；
S13: according to each state x in x (t) and q (t)_{i}And q_{j}Corresponding joint probability P_{xq}(x_{i},q_{j}), it calculates according to the following formula
Conditional entropy H (q  x) of the q (t) for x (t):
Wherein, H (x, q) is combination entropy of the q (t) for x (t), and H (x, q) is according to each state x in x (t) and q (t)_{i}And q_{j}
Corresponding joint probability P_{xq}(x_{i},q_{j}), it is calculated according to the following formula:
S14: according to the I (q, x) obtained by H (q) and H (q  x), determine that first local minizing point is corresponding in I (q, x)
Optimum delay time of the τ as phase space reconstruction；
Wherein,
It should be noted that I (q, x) is the mutual information function of q (t) and x (t).
Optionally, the smallest embedding dimension number of phase space reconstruction is determined according to optimum delay time, specific steps include:
S31: according to the point Y of phase space reconstruction_{u}(m), calculating matrix a (u, m) according to the following formula:
Wherein, m is the dimension of phase space reconstruction, Y_{x(u,m)}It (m) is distance Y_{u}(m) nearest point, x (u, m) be greater than 1 and
Less than or equal to the integer of Nm τ；
S32: according to the following formula in calculating matrix a (u, m) all elements mean value E (m):
When the value of dimension m is greater than m_{0}, and when the value of E (m) will not change, enable the smallest embedding dimension number mb=m_{0}+1。
Optionally, the correlation dimension of phase space reconstruction is determined according to smallest embedding dimension number, specific steps include:
S41: according to smallest embedding dimension number mb, the point Y (t) in phase space reconstruction is determined:
Y (t)={ y (t), y (t+ τ) ..., y [t+ (mb1) τ] }, t=1,2 ..., N (mb1) τ,
It is understood that mb=m_{0}+ 1, herein, in multidimensional phase space, point is indicated with an ordered series of numbers；
S42: any one point chosen in N number of point that phase space reconstruction includes is as a reference point；
The N1 point in addition to reference point is calculated to the distance of the reference point, determines to be less than at a distance from reference point and give
The point of definite value r is relating dot；
Accounting C of the number of the relating dot in all possible relating dot number N (N1) is calculated according to the following formula_{mb}
(r):
Wherein, Y (i), Y (j) are respectively the ith and jth element in the Y (t), and θ is Heaviside unit function；
S43: according to C_{mb}(r) with the relationship of the rCalculate the correlation dimension P.
Optionally, lnC is made under smallest embedding dimension number_{mb}(r)=lnr curve determines the uncalibrated visual servo section of curve, nothing
Scale section is linear segments or nearlinear section, and uncalibrated visual servo section is fitted to a fitting a straight line, digital simulation straight line
Slope, using the slope of fitting a straight line as correlation dimension P.
Optionally, it obtains correlation dimension in advance and is grounded the corresponding relationship of medium type, specific steps include:
S51: the zerosequence current of the onephase earthing failure in electric distribution network phase of the known ground connection medium type of measurement, the known ground connection
Medium type including at least wet soil, dry earth, wet sand, dry sand ground, wet cement, wet branch and water resistance.It needs to illustrate
Be, used in the present embodiment known to this seven kinds be grounded medium type it is only schematical, be not construed as limiting, it is specifically used which
A little known ground connection media specifically depend on the circumstances.
S52: according to step S1, the waveform of the zerosequence current of the singlephase earth fault phase of known ground connection medium type is carried out
Phase space reconfiguration.
S53: according to step S11S12, the optimum delay time of phase space reconstruction is determined.
Specifically, according to step S11S12 be calculated ground connection medium be respectively wet soil, dry earth, wet sand, dry sand
Optimum delay time when ground, wet cement, wet branch and water resistance.
S11: according to state x each in original time series x (t)_{i}Corresponding Probability p_{x}(x_{i}), the x is calculated according to the following formula
(t) comentropy H (x):
S12: according to each state q in the time series q (t) after original time series x (t) delay τ_{j}Corresponding probability
P_{q}(q_{j}), the comentropy H (q) of the q (t) is calculated according to the following formula:
Wherein it is possible to which that understand is q (t)=x (t+ τ)；
S13: according to each state x in x (t) and q (t)_{i}And q_{j}Corresponding joint probability P_{xq}(x_{i},q_{j}), it calculates according to the following formula
Conditional entropy H (q  x) of the q (t) for x (t):
Wherein, H (x, q) is combination entropy of the q (t) for x (t), and H (x, q) is according to each state x in x (t) and q (t)_{i}And q_{j}
Corresponding joint probability P_{xq}(x_{i},q_{j}), it is calculated according to the following formula:
S14: according to the I (q, x) obtained by H (q) and H (q  x), the mutual information function I (q, x) of q (t) He x (t), I are determined
Optimum delay time of the corresponding τ of first local minizing point as phase space reconstruction in (q, x)；
Wherein,
The sample frequency of zerosequence current is arranged in 20000Hz in the present embodiment, and the frequency of power supply is 50Hz, therefore, zero sequence
Have 400 sampled points in each cycle of electric current, when making image, consider delay time bound limitation, take 0 to 200 it
Between optimum delay time of the corresponding τ of first more apparent local minizing point as its phase space reconstruction.
Specifically, with reference to Fig. 2 a2g, Fig. 2 a be grounded medium be wet soil when delay time and mutual information function pass
It is curve, Fig. 2 b is the relation curve for being grounded delay time and mutual information function when medium is dry earth, and Fig. 2 c is that ground connection is situated between
Matter be wet sand when delay time and mutual information function relation curve, Fig. 2 d is the delay for being grounded medium when being dry sand ground
The relation curve of time and mutual information function, Fig. 2 e be grounded medium be wet cement when delay time and mutual information function
Relation curve, Fig. 2 f is the relation curve for being grounded delay time and mutual information function of the medium when being wet branch, and Fig. 2 g is to connect
The relation curve of delay time and mutual information function when ground medium is water resistance.It is situated between by several ground connection are shown respectively in Fig. 2 a2g
The delay time of matter obtains with the curve of its mutual information function, first local minizing point corresponding delay time in curve
92s, 56s, 68s, 112s, 78s, 50s, 106s respectively, so, ground connection medium be respectively wet soil, dry earth, wet sand,
Dry sand ground, wet cement, wet branch and water resistance optimum delay time be respectively 92s, 56s, 68s, 112s, 78s, 50s, 106s.
It should be noted that known ground connection medium type provided by the present embodiment (wet soil, dry earth, wet sand, it is dry
Sand ground, wet cement, wet branch and water resistance) real data derive from highlands, real data is only schematical, does not do
It is specific to limit.
S54: the best insertion of corresponding each phase space reconstruction is determined according to the optimum delay time of each ground connection medium
Dimension；
Specifically, the smallest embedding dimension of the corresponding phase space reconstruction of every kind of ground connection medium is calculated according to S31S32
Number.
S31: according to the point Y of phase space reconstruction_{u}(m), calculating matrix a (u, m) according to the following formula:
Wherein, m is the dimension of phase space reconstruction, Y_{x(u,m)}It (m) is distance Y_{u}(m) nearest point, x (u, m) be greater than 1 and
Less than or equal to the integer of Nm τ；
S32: according to the following formula in calculating matrix a (u, m) all elements mean value E (m):
When the value of dimension m is greater than m_{0}, and when the value of E (m) will not change, enable the smallest embedding dimension number mb=m_{0}+1。
It is respectively that 92s, 56s, 68s, 112s, 78s, 50s, 106s bring E (m) by optimum delay time, what is obtained is best
Embedded dimensions are respectively 8,13,10,15,7,11,5.
Specifically, referring to shown in table 1, table 1 is the optimum delay time and most for being grounded medium type and its phase space reconstruction
The mapping table of good Embedded dimensions.
Table 1
It is grounded medium type  Delay time (s)  Smallest embedding dimension number 
Wet soil  92  8 
Dry earth  56  13 
Wet sand  68  10 
Dry sand ground  112  15 
Wet cement  78  7 
Wet branch  50  11 
Water resistance  106  5 
S55: the correlation dimension of phase space reconstruction is determined according to step S41S43.
Specifically, S41: smallest embedding dimension number mb, mb=m_{0}+ 1, determine the point Y (t) in phase space reconstruction:
Y (t)=y (t), y (t+ τ) ..., y [t+ (mb1) τ] }, t=1,2 ..., N (mb1) τ；
S42: any one point chosen in N number of point that phase space reconstruction includes is as a reference point；
The N1 point in addition to reference point is calculated to the distance of the reference point, determines to be less than at a distance from reference point and give
The point of definite value r is relating dot；
Accounting C of the relating dot number in all possible relating dot number N (N1) is calculated according to the following formula_{mb}(r):
Wherein, Y (i), Y (j) are respectively the ith and jth element in the Y (t), and θ is Heaviside unit function；
S43: according to C_{mb}(r) with the relationship of the rCalculate the correlation dimension P.
Optionally, lnC is made under smallest embedding dimension number_{mb}(r)=lnr curve determines the uncalibrated visual servo section of curve, nothing
Scale section is linear segments or nearlinear section, and uncalibrated visual servo section is fitted to a fitting a straight line, digital simulation straight line
Slope, correlation dimension P are the slope of fitting a straight line.
S55: obtaining correlation dimension in advance and is grounded the corresponding relationship of medium type.Specifically, referring to Fig. 3 a3g, Fig. 3 a
For ground connection medium be wet soil when smallest embedding dimension number under lnC_{mb}(r)=lnr curve graph, Fig. 3 b are that ground connection medium is dry ground
LnC under smallest embedding dimension number when ground_{mb}(r)=lnr curve graph, Fig. 3 c be ground connection medium be wet sand when smallest embedding dimension number
Lower lnC_{mb}(r)=lnr curve graph, Fig. 3 d are ground connection medium lnC under smallest embedding dimension number when being dry sand ground_{mb}(r)=lnr
Curve graph, Fig. 3 e are ground connection medium lnC under smallest embedding dimension number when being wet cement_{mb}(r)=lnr curve graph, Fig. 3 f are ground connection
LnC under smallest embedding dimension number when medium is wet branch_{mb}(r)=lnr curve graph, Fig. 3 g are best when medium is water resistance to be grounded
LnC under Embedded dimensions_{mb}(r)=lnr curve graph.LnC is made under the smallest embedding dimension number of each ground connection medium type_{mb}
(r)=lnr curve, by mb=m_{0}+ 1 brings into, and each Embedded dimensions mb corresponds to a curve, and each curve has one section
Uncalibrated visual servo section, uncalibrated visual servo section are linear segments or nearlinear section, and it is straight that uncalibrated visual servo section is fitted to a fitting
Line, the slope of this fitting a straight line are the correlation dimension P of phase space reconstruction_{n}。
The calculation formula of correlation dimension is as follows:
Wherein, L indicates r_{in}The total number of value, n indicate ground connection medium type coding, n=1,2,3,4,5,6,7 difference tables
With showing ground connection medium water resistance, wet cement, wet soil, wet sand, the coding of wet branch, dry earth and dry sand ground；
According to known ground connection medium type and pass through the abovementioned corresponding correlation dimension being calculated, obtains correlation dimension in advance
The corresponding relationship of number and ground connection medium type, as shown in table 2, table 2 are the correlation dimension obtained in advance and ground connection medium type
Mapping table.
Table 2
It is grounded medium type  Correlation dimension (slope of curve) 
Wet soil  P_{3}=1.2166 
Dry earth  P_{6}=2.8613 
Wet sand  P_{7}=1.4489 
Dry sand ground  P_{4}=3.2101 
Wet cement  P_{2}=1.1210 
Wet branch  P_{5}=1.6812 
Water resistance  P_{1}=1.0298 
Optionally, it is calculated, is obtained opposite by step S51S55 according to the corresponding zerosequence current of unknown ground connection medium type
The correlation dimension for the phase space reconstruction answered.By the correlation dimension of unknown ground connection medium type and the correlation dimension that in advance obtains with
The corresponding relationship of ground connection medium type is made comparisons, and determines the ground connection medium type of singlephase earth fault.Correlation dimension and ground connection are situated between
The corresponding relationship of matter type, comprising:
Work as P_{1}< P < P_{2}, determine that the ground connection medium type is wet cement；
Work as P_{2}< P < P_{3}, determine the ground connection medium type for wet soil；
Work as P_{3}< P < P_{4}, determine the ground connection medium type for wet sand；
Work as P_{4}< P < P_{5}, determine that the ground connection medium type is wet branch；
Work as P_{5}< P < P_{6}, determine that the ground connection medium type is dry earth；
Work as P_{6}< P < P_{7}, determine that the ground connection medium type is dry sand ground；
As P < P_{1}, determine that the ground connection medium type is water resistance；
Wherein, P is that the corresponding zerosequence current of unknown ground connection medium passes through the correlation dimension being calculated.
Method provided by the present application, from the angle of the zerosequence current Wave data of singlephase earth fault phase, using phase
Space Reconstruction method analyzes the corresponding zerosequence current waveform of different ground connection media, according to the optimum delay time of phase space reconstruction
Correlation dimension is determined with smallest embedding dimension number, passes through correlation dimension and the correlation dimension and ground connection medium type that in advance obtain
Corresponding relationship, determine it is unknown ground connection medium type.Compare the prior art, and this method can more accurately determine singlephase
The ground connection medium type of ground fault.
It is required that those skilled in the art can be understood that the technology in the embodiment of the present invention can add by software
The mode of general hardware platform realize.Based on this understanding, the technical solution in the embodiment of the present invention substantially or
Say that the part that contributes to existing technology can be embodied in the form of software products, which can be with
It is stored in a storage medium, such as ROM/RAM, magnetic disk, CD, including some instructions are used so that a computer equipment
(can be personal computer, server or the network equipment etc.) executes the certain of each embodiment or embodiment of the invention
Method described in part.
Same and similar part may refer to each other between each embodiment in this specification.Especially for embodiment
Speech, since it is substantially similar to the method embodiment, so being described relatively simple, related place is referring in embodiment of the method
Explanation.
Claims (7)
1. a kind of determination method of the ground connection medium type of onephase earthing failure in electric distribution network, which is characterized in that the described method includes:
When singlephase earth fault occurs for power distribution network, according to the original time sequence of the zerosequence current of onephase earthing failure in electric distribution network phase
Column carry out phase space reconfiguration to the waveform of the zerosequence current；
Determine the optimum delay time of phase space reconstruction；
The smallest embedding dimension number of the phase space reconstruction is determined according to the optimum delay time；
The correlation dimension of the phase space reconstruction is determined according to the smallest embedding dimension number；
The corresponding relationship of the correlation dimension and ground connection medium type that obtain according to the correlation dimension and in advance, determines described singlephase
The ground connection medium type of ground fault.
2. the method according to claim 1, wherein when the optimal delay of the determining phase space reconstruction
Between, comprising:
According to state x each in the original time series x (t)_{i}Corresponding Probability p_{x}(x_{i}), the x (t) is calculated according to the following formula
Comentropy H (x):
According to each state q in the time series q (t) after the original time series x (t) delay τ_{j}Corresponding probability P_{q}
(q_{j}), the comentropy H (q) of the q (t) is calculated according to the following formula:
According to each state x in the x (t) and q (t)_{i}And q_{j}Corresponding joint probability P_{xq}(x_{i},q_{j}), according to the following formula described in calculating
Conditional entropy H (q  x) of the q (t) for x (t):
Wherein, H (x, q) is combination entropy of the q (t) for the x (t), and the H (x, q) is according in the x (t) and q (t)
Each state x_{i}And q_{j}Corresponding joint probability P_{xq}(x_{i},q_{j}), it is calculated according to the following formula:
According to the I (q, x) obtained by the H (q) and the H (q  x), determine that first local minizing point is corresponding in I (q, x)
Optimum delay time of the τ as the phase space reconstruction；
Wherein,
3. according to the method described in claim 2, it is characterized in that, described determine that the reconstruct is mutually empty according to optimum delay time
Between smallest embedding dimension number, comprising:
According to the point Y of the phase space reconstruction_{u}(m), calculating matrix a (u, m) according to the following formula:
Wherein, m is the dimension of the phase space reconstruction, Y_{x(u,m)}It (m) is distance Y_{u}(m) nearest point, x (u, m) are greater than 1 and small
In the integer for being equal to Nm τ；
According to the following formula in calculating matrix a (u, m) all elements mean value E (m):
When the value of the dimension m is greater than m_{0}, and when the value of E (m) will not change, enable the smallest embedding dimension number mb=m_{0}+1。
4. according to the method described in claim 3, it is characterized in that, described determine that the reconstruct is mutually empty according to smallest embedding dimension number
Between correlation dimension, include:
According to the smallest embedding dimension number mb, the point Y (t) in the phase space reconstruction is determined:
Y (t)=y (t), y (t+ τ) ..., y [t+ (mb1) τ] }, t=1,2 ..., N (mb1) τ；
Any one point chosen in N number of point that the phase space reconstruction includes is as a reference point；
The N1 point in addition to reference point is calculated to the distance of the reference point, determines to be less than at a distance from the reference point and give
The point of definite value r is relating dot；
Accounting C of the number of the relating dot in all possible relating dot number N (N1) is calculated according to the following formula_{mb}(r):
Wherein, Y (i), Y (j) are respectively the ith and jth element in the Y (t), and θ is Heaviside unit function；
According to the C_{mb}(r) with the relationship of the rCalculate the correlation dimension P.
5. according to the method described in claim 4, it is characterized in that, the calculating correlation dimension P includes:
LnC is made at the smallest embedding dimension number mb_{mb}(r)=lnr curve confirms the uncalibrated visual servo section of the curve, institute
Stating uncalibrated visual servo section is linear segments or nearlinear section, and the uncalibrated visual servo section is fitted to a fitting a straight line, calculates institute
The slope for stating fitting a straight line, using the slope of the fitting a straight line as the correlation dimension P.
6. according to the method described in claim 5, it is characterized in that, as steps described below, obtaining correlation dimension and ground connection in advance
The corresponding relationship of medium type, comprising:
The zerosequence current that the onephase earthing failure in electric distribution network phase of medium is grounded known to every kind, the known ground connection medium are measured respectively
Including at least wet soil, dry earth, wet sand, dry sand ground, wet cement, wet branch and water resistance；
According to the original time series of the zerosequence current, phase space reconfiguration is carried out to the waveform of the zerosequence current；
Determine the optimum delay time of phase space reconstruction；
The smallest embedding dimension number of the phase space reconstruction is determined according to the optimum delay time；
The correlation dimension P of the phase space reconstruction is determined according to the smallest embedding dimension number_{n}:
Wherein, L indicates r_{in}The total number of value, n indicate ground connection medium type coding, and n=1,2,3,4,5,6,7 respectively indicate and connect
Ground medium water resistance, wet cement, wet soil, wet sand, the coding of wet branch, dry earth and dry sand ground；
According to the type of known ground connection medium and the correlation dimension, it is corresponding with ground connection medium type that correlation dimension is obtained in advance
Relationship.
7. according to the method described in claim 6, it is characterized in that, the corresponding pass of the correlation dimension and ground connection medium type
System, comprising:
Work as P_{1}< P < P_{2}, determine that the ground connection medium type is wet cement；
Work as P_{2}< P < P_{3}, determine the ground connection medium type for wet soil；
Work as P_{3}< P < P_{4}, determine the ground connection medium type for wet sand；
Work as P_{4}< P < P_{5}, determine that the ground connection medium type is wet branch；
Work as P_{5}< P < P_{6}, determine that the ground connection medium type is dry earth；
Work as P_{6}< P < P_{7}, determine that the ground connection medium type is dry sand ground；
As P < P_{1}, determine that the ground connection medium type is water resistance；
Wherein, P is that the corresponding zerosequence current of unknown ground connection medium passes through the correlation dimension being calculated.
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