CN109961227A - The forecast failure screening and sort method that a kind of three-level is coordinated - Google Patents
The forecast failure screening and sort method that a kind of three-level is coordinated Download PDFInfo
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Abstract
The forecast failure screening coordinated the present invention relates to a kind of three-level and sort method, comprising steps of various operation metric data, fault data when 1) obtaining distribution network failure, establish fault history metric data library；2) fault data provided according to step 1), voltage stabilization screening and sequence index of load margin screening of the branch parameters screening with sequence index, based on sensitivity with sequence index, based on synchronized phasor are established respectively, and branch parameters screening and sequence, load margin screening and sequence and voltage stabilization screening and sequence are successively carried out by coordinating progressive screening mode, realize that forecast failure quick and precisely screens；3) the serious forecast failure of influence system safe and stable operation is exported.Compared with prior art, the present invention realizes mutually coordinated, quick system failure collection screening and sequence.
Description
Technical field
The present invention relates to a kind of screening of power distribution network forecast failure collection and sort methods, coordinate more particularly, to a kind of three-level
Forecast failure screening and sort method.
Background technique
With the continuous development that distribution network construction is transformed, the addition of distributed generation resource, electric car and a large amount of new elements
Increase the risk of failure, and the expansion of power grid scale increases the range of failure influence, the strong influence peace of power distribution network
Full stable operation, and then constrain the development of extensive interconnection power distribution network.This is because failure is many kinds of, failure it is serious
Degree is had nothing in common with each other, and can not make corresponding safeguard measure in time so as to cause the protective device of power distribution network itself.In this regard, needing to mention
The quick screening of suitable power distribution network forecast failure and accurate sort method out, to enhance the energy that power distribution network copes with various failures
Power further increases the ability of power distribution network anticipation failure.The prior art considers to carry out forecast failure collection using single index mostly
Screening and sequence, consider leakage choosing or multiple indexs situations such as being screened, cause the accuracy rate of Contingency screening not high, and
Efficiency is lower.
Summary of the invention
It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art and provide a kind of three-level coordinate it is pre-
Think Contingency screening and ranking method.
The purpose of the present invention can be achieved through the following technical solutions:
The forecast failure screening and sort method that a kind of three-level is coordinated, for improving Contingency screening rate, effective acquisition system
Larger fault set, method includes the following steps:
Step 1: various operation metric data, fault data when obtaining distribution network failure, establish fault history and measure number
According to library.
Operation metric data when distribution network failure includes PMU metric data, SCADA data and fault moment power distribution network fortune
The failure metric data library of the buildings such as row data.
Step 2: establishing branch parameters screening and sequence index respectively, based on spirit according to the fault data that step 1 provides
Voltage stabilization screening of the load margin screening of sensitivity with sequence index, based on synchronized phasor and sequence index, and pass through coordination
Progressive screening mode successively carry out branch parameters screening with sequence, load margin screening with sequence and voltage stabilization screening with
Sequence realizes that forecast failure quick and precisely screens.Detailed process are as follows:
1) the initial forecast failure collection in fault data historical metrology data library provided according to step 1；
2) branch parameters screening and sequence index are established；
3) it is screened and the index selection key forecast failure set that sorts according to branch parameters；
4) load margin screening and sequence index based on sensitivity are established；
5) it is screened and the serious forecast failure set of index selection that sorts according to load margin；
6) voltage stabilization screening and sequence index based on synchronized phasor are established；
7) fault set screening and sequence are carried out in conjunction with serious forecast failure according to crucial forecast failure set.
Wherein, the particular content of branch parameters screening with sequence index is established are as follows:
Using the operation data of fault moment power distribution network branch by normalized, forecast failure collection is tentatively sieved
Choosing, and studied under fault condition by improved level Clouds theory, between voltage, short circuit current, active power and reactive loss
Weight relationship.The significance level of branch can be measured in electric power networks research by following characteristics parameter.
A) voltage: the randomness that usual distribution network failure occurs, line voltage distribution reflects that the branch is influenced by failure after failure
Degree, therefore can be used for reacting the significance level of branch；
B) electric current: the size of short circuit current reflects the electrical distance of fault point distance power supply point after failure, therefore available
In the significance level of reaction branch；
C) active transimission power；Active transimission power can reflect weight of the branch in entire power grid to a certain extent
Degree is wanted, active transimission power is bigger, then shows that the branch is more important；
D) reactive loss: the size of branch reactive loss had both included the information of transmission capacity size, also contain electrically away from
Information from length, therefore can be used for reflecting the significance level of the branch.
According to above-mentioned analysis, place is normalized in branch voltage, short circuit current, active transimission power and reactive loss
Reason, for calculating branch parameters screening and sequence index, for branch L, branch parameters voltage indexes SLAre as follows:
In formula: L represents branch, VL、IL、PL、ΔQLRespectively indicate voltage, short circuit current, active power and the nothing of branch L
Function loss, ω is voltage, short circuit current, active and reactive loss weight coefficient, and is solved using improved level Clouds theory
Weight coefficient ω1、ω2、ω3、ω4。
Improved level Clouds theory: Clouds theory can by expectation Ex, entropy En and super entropy He by numerical characteristic be randomness,
Ambiguity and discreteness three are mutually merged, and are realized the function of qualitative and quantitative data random transition.Currently, Clouds theory is
It is widely used in the processing of nature sentence, the various fields such as big data analysis, Analysis of Policy Making image procossing.
If U is a quantitative domain indicated with exact numerical, X is the qualitativing concept on U, if quantitative values x ∈ U, and x is
A Stochastic implementation of qualitativing concept X, while x meets x:N (Ex, En2), u ∈ [0,1], wherein En:N (En, He2), then x is to X
Degree of certainty meet:
In formula: Ex is expectation, and En is variance, then x meets Normal Cloud on the U of field, and (x, u) is known as water dust and u (X): U
→ [0,1],x→u(X)。
Analytic hierarchy process (AHP) is that a kind of one kind decision-making technique that is qualitative and quantitatively solving the problems, such as according to the actual situation can be by it
It is divided into destination layer, rule layer and measure layer.By being compared two-by-two each index, by its importance degree rating, shape
At judgment matrix, and the feature vector of judgment matrix is found out, carry out consistency check, if the consistency check of judgment matrix is logical
It crosses, can get weight order of this layer relative to upper layer, otherwise need to adjust judgment matrix until passing through consistency check.Cause
This, analytic hierarchy process (AHP) uses relatively small number of quantitative relationship, and easy decision scheme is provided for multifactor challenge.This
Patent of invention constructs the level Clouds theory of branch parameters screening index, as shown in Figure 3.Traditional analytic hierarchy process (AHP) using integer and
Its inverse determines index weights, does not fully consider randomness, ambiguity between factor, therefore can be based on the building of Clouds theory
Index weights construct nine cloudlets theory using Fibonacci method, can obtain the entropy and super entropy of every cloudlet theory.
Each index of a certain layer can be obtained according to thinking above to judge relative to the importance two-by-two of upper one layer of a certain index
Matrix is as follows:
And have:
It is solved using root method, there is following steps:
A) to UijBy row quadrature, obtain
B) willNormalization, obtainsThen ω=(ω1,ω2,…,ωn)TFor weight vectors；
C) the maximum eigenvalue λ of judgment matrix is calculatedmax
Wherein U is judgment matrix；W is weight vectors；N is judgment matrix order；ωiFor i characteristic value.
D) using CI as index of conformity, RI is average homogeneity index, CR is calculated, as CR < 0.1, it is believed that U meets one
Cause property, otherwise should rebuild judgment matrix.
The acquisition content of branch parameters screening and sequence index are as follows:
Wherein:
Finally acquire whole associated weights ω:
Branch parameters screening and sequence index S L can be asked, initial forecast failure is sorted from large to small according to the index, is chosen
Several failures enter crucial forecast failure collection, participate in load margin screening and sequence based on sensitivity.This stage can be with
A large amount of minor failures are weeded out by less calculation amount and time, forecast failure collection range are greatly reduced, after reducing
It is continuous to calculate the time.
Obtain the load margin screening based on sensitivity and the particular content of sequence index are as follows: utilize negative based on sensitivity
Lotus nargin screening index to the lesser Contingency screening of failure afterload nargin and sorts.
If the parametrization power flow equation of system are as follows:
In formula: x ∈ RnIt is system state variables vector, such as node current amplitude and phase angle；λ ∈ R is load parameter；p
∈RMFor parameter vector, such as the active power and reactive power etc. of generator；F () is n dimension power flow equation；H () is one
Dimension parametrization equation.In saddle node bifurcation point, h () is to may insureNonsingular arc length or quasi- arc length parameterized equation.
In voltage collapse point, calculation formula of the various parameters to the sensitivity of stability margin index are as follows:
In formula: w is a row vector at system voltage collapse point, " |*" indicate the value at bifurcation point.If certain hair
For motor because failure is out of service, dispatcher then can be by increasing some unit outputs or putting into operation active and idle to compensate
Missing volume, these units are referred to as offset electricity generation unit, and every ratio for undertaking missing volume is then known as participating in the factor.
For fault branch L, the changing value of stability margin can be used following formula to indicate:
In formula:Qg,iRespectively generator active power and reactive power output valve；Respectively generator
Sensitivity of the stability margin to active and idle output valve when failure.Ωk.pCompensated dynamo set under the conditions of expression failure K,
Middle compensated dynamo j can be represented by the formula stability margin influence:
In formula: Ωk.IFor fault generator set, Ωk.TFor fault branch set；λ0Be before failure system stablize it is abundant
Degree.Screening technique are as follows: sort from small to large according to load margin, wherein the smallest point of load margin is known as system tender spots.Base
It is fast in the load margin evaluation method calculating speed of sensitivity, but it be not be accurately likely to leakage the case where selecting occur very much, wherein
Possibly even include each failure for causing system unstability, therefore propose based on synchronous phasor measurement voltage stabilization screening with
Sort index.
Based on synchronized phasor voltage stabilization screening with sequence index be calculate failure after Voltage Instability value size side by side
Sequence.
The voltage stabilization screening and sequence index, Line Flow for constructing synchronized phasor meet following formula:
Vjcosθ-ViVjcos(θ-δ)+PjZ=0
In formula: PjFor active power at node j, divide Vi、VjVoltage magnitude respectively at i, j, Z are the equivalent resistance of route
Anti- value, θ are the impedance angle of route, and δ is node voltage differential seat angle.Under conditions of considering that linear equation in two unknowns has solution, it is based on above formula
Voltage stabilization screening and sequence index based on synchronized phasor can be obtained by deriving from mathematical angle.The present invention is from the angle of P-V curve
It is analyzed on degree, and considers that collapse of voltage point solves index.
First by above formula to VjDerivation:
It arranges:
According to P-V curve it is found that meeting following relationship in collapse of voltage point；
Then have:
And system is when operating normally:
Therefore it is as follows to define voltage stability index:
The normal variation range of the index is 0 < Ev< 1, in Voltage Instability critical point Ev=1.It is fixed for whole system
Adopted voltage stability index is as follows:
Ev=Ev,ij=max { Ev1,…,Evn}
Synchronized phasor voltage stabilization is based on as whole system using index maximum value to screen and the index that sorts.The index calculates institute
It needs physical quantity relatively fewer, and is branch information, can all be surveyed and be obtained by PMU.The index is calculated and utilized, is realized quick
More serious failure can also be ranked up catastrophe failure according to index size simultaneously in screening system.
Step 3: the serious forecast failure of output influence system safe and stable operation.
The Contingency screening and ranking coordinated for three-level is as a result, output influences the relatively die of power distribution network safe and stable operation
Barrier, obtains final system fault set.According to the type and severity of the system failure collection of acquisition, take for the system failure
Cope with maintenance measure or safeguard measure.
Compared with prior art, the invention has the following advantages that
(1) present invention coordinates screening and sort method using three-level forecast failure, refers to from branch parameters screening and sequence
Mark, the screening of load margin based on sensitivity and sequence index, voltage stabilization screening and sequence index based on synchronized phasor
Three angles analyze forecast failure, and calculate corresponding index, realize mutually coordinated, quick system failure collection
Screening and sequence；
(2) present invention obtains weight coefficient using improved level Clouds theory, passes through level in improved level Clouds theory
Analytic approach is compared the index of acquisition, to determine index weights, has fully considered randomness, the ambiguity between factor, into
And improve the accuracy of the weight coefficient of acquisition；
(3) branch parameters screening is being obtained with sequence index, initial forecast failure is arranged from big to small according to the index
Sequence chooses several failures and enters crucial forecast failure collection, participates in load margin screening and sequence based on sensitivity, this single order
Section can weed out a large amount of minor failures by less calculation amount and time, greatly reduce forecast failure collection range, subtract
The subsequent calculating time is lacked；
(4) Contingency screening and ranking that the present invention is coordinated using three-level, can accurately export influences power distribution network safety and stability
The relatively major break down of operation, and then system failure collection is obtained, it, can be into one according to the type and severity of the system failure collection of acquisition
Step takes reply maintenance measure or safeguard measure for system difference severity failure, and helps to improve distribution network system
Cope with the ability of various failures and the ability of power distribution network anticipation failure.
Detailed description of the invention
Fig. 1 is the flow diagram of the method for the present invention；
Fig. 2 is the flow diagram that fault set is screened and sorted；
Fig. 3 is branch parameters assessment indicator system schematic diagram；
Fig. 4 is the flow diagram for obtaining branch parameters index；
Fig. 5 is the π type equivalent circuit schematic diagram for constructing the voltage of synchronized phasor in the embodiment of the present invention using branch；
Fig. 6 is IEEE33 system diagram；
Fig. 7 is 6 node voltages in the embodiment of the present invention with load growth rate variation diagram；
Fig. 8 is voltage stability index in the embodiment of the present invention with load growth change rate variation diagram.
Specific embodiment
The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.Obviously, described embodiment is this
A part of the embodiment of invention, rather than whole embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art exist
Every other embodiment obtained under the premise of creative work is not made, all should belong to the scope of protection of the invention.
The forecast failure screening and sort method, this method that a kind of three-level is coordinated include the following steps:
Step 1: various operation metric data, fault data when obtaining distribution network failure, establish fault history and measure number
According to library.
Operation metric data when distribution network failure includes PMU metric data, SCADA data and fault moment power distribution network fortune
The failure metric data library of the buildings such as row data.
Step 2: establishing branch parameters screening and sequence index respectively, based on spirit according to the fault data that step 1 provides
Voltage stabilization screening of the load margin screening of sensitivity with sequence index, based on synchronized phasor and sequence index, and pass through coordination
Progressive screening mode successively carry out branch parameters screening with sequence, load margin screening with sequence and voltage stabilization screening with
Sequence realizes that forecast failure quick and precisely screens.
Analytic hierarchy process (AHP) is that a kind of one kind decision-making technique that is qualitative and quantitatively solving the problems, such as according to the actual situation can be by it
It is divided into destination layer, rule layer and measure layer.By being compared two-by-two each index, by its importance degree rating, shape
At judgment matrix, and the feature vector of judgment matrix is found out, carry out consistency check, if the consistency check of judgment matrix is logical
It crosses, can get weight order of this layer relative to upper layer, otherwise need to adjust judgment matrix until passing through consistency check.Cause
This, analytic hierarchy process (AHP) uses relatively small number of quantitative relationship, and easy decision scheme is provided for multifactor challenge.This
Patent of invention constructs the level Clouds theory of branch parameters screening index, as shown in Figure 3.Traditional analytic hierarchy process (AHP) using integer and
Its inverse determines index weights, does not fully consider randomness, ambiguity between factor, therefore can be based on the building of Clouds theory
Index weights construct nine cloudlets theory using Fibonacci method, and entropy and the super entropy that can obtain every cloudlet theory are as shown in table 1.
1 Clouds theory scale of table
Wherein:
En1=En5=En7=En9=0.437
En2=En4=En6=En8=En1/ 0.618=0.707
He1=He3=He5=He7=0.073
He2=He4=He6=He8=He1/ 0.618=0.118
Each index of a certain layer can be obtained according to thinking above to judge relative to the importance two-by-two of upper one layer of a certain index
Matrix is as follows:
And have:
It is solved using root method, there is following steps:
A) to UijBy row quadrature, obtain
B) willNormalization, obtainsThen ω=(ω1,ω2,…,ωn)TFor weight vectors；
C) the maximum eigenvalue λ of judgment matrix is calculatedmax:
Wherein U is judgment matrix；W is weight vectors；N is judgment matrix order；ωiFor i characteristic value.
D) using CI as index of conformity, RI is average homogeneity index, CR is calculated, as CR < 0.1, it is believed that U meets one
Cause property, otherwise should rebuild judgment matrix.
Branch parameters screening and the flow chart of sequence index are as shown in Figure 4:
Wherein:
Finally acquire whole associated weights ω:
Branch parameters screening and sequence index S L can be asked, initial forecast failure is sorted from large to small according to the index, is chosen
Several failures enter crucial forecast failure collection, participate in load margin screening and sequence based on sensitivity.This stage can be with
A large amount of minor failures are weeded out by less calculation amount and time, forecast failure collection range are greatly reduced, after reducing
It is continuous to calculate the time.
Obtain the load margin screening based on sensitivity and the particular content of sequence index are as follows: utilize negative based on sensitivity
Lotus nargin screening index to the lesser Contingency screening of failure afterload nargin and sorts.
Based on synchronized phasor voltage stabilization screening with sequence index be calculate failure after Voltage Instability value size side by side
Sequence.
The voltage stabilization screening of branch building synchronized phasor and sequence index, Line Flow meet following formula according to Fig.5:
Vjcosθ-ViVjcos(θ-δ)+PjZ=0
In formula: PjFor active power at node j, divide Vi、VjVoltage magnitude respectively at i, j, Z are the equivalent resistance of route
Anti- value, θ are the impedance angle of route, and δ is node voltage differential seat angle.Under conditions of considering that linear equation in two unknowns has solution, it is based on above formula
Voltage stabilization screening and sequence index based on synchronized phasor can be obtained by deriving from mathematical angle.This patent is from the angle of P-V curve
It is analyzed on degree, and considers that collapse of voltage point solves index.
First by above formula to VjDerivation:
It arranges:
According to P-V curve it is found that meeting following relationship in collapse of voltage point；
Then have:
And system is when operating normally:
Therefore it is as follows to define voltage stability index:
The normal variation range of the index is 0 < Ev< 1, in Voltage Instability critical point Ev=1.It is fixed for whole system
Adopted voltage stability index is as follows:
Ev=Ev,ij=max { Ev1,…,Evn}
Synchronized phasor voltage stabilization is based on as whole system using index maximum value in embodiment to screen and the index that sorts.This refers to
Physical quantity needed for mark calculates is relatively fewer, and is branch information, can all be surveyed and be obtained by PMU.The index is calculated and utilizes,
It realizes failure more serious in quick screening system while catastrophe failure can also be ranked up according to index size.
Step 3: the serious forecast failure of output influence system safe and stable operation.
The Contingency screening and ranking coordinated for three-level is as a result, output influences the relatively die of power distribution network safe and stable operation
Barrier, obtains final system fault set.According to the type and severity of the system failure collection of acquisition, take for the system failure
Cope with maintenance measure or safeguard measure.
The invention patent coordinates screening and sort method using three-level forecast failure, refers to from branch parameters screening and sequence
Mark, the screening of load margin based on sensitivity and sequence index, voltage stabilization screening and sequence index based on synchronized phasor
Three angles analyze forecast failure, and calculate corresponding index, realize mutually coordinated, quick system failure collection
Screening and sequence.
This example is by taking IEEE33 system as an example, is 12.66kV (such as Fig. 6) with reference voltage.It is reliable according to existing electric power
Property report it is found that influence distribution network failure safety at power cut in natural cause account for 30%, apparatus factor accounts for 21.01%, wherein equipment
Aging accounts for the 70% of apparatus factor, and external force factor accounts for 20.85%, wherein share accounting of the foreign matter short circuit in external force factor compared with
Greatly.The failure rate of 10 kilovolts of accessory net capital equipments (overhead line, cable circuit, transformer, breaker) is as shown in table 2:
2 capital equipment failure rate of table
It is reported based on existing electric reliability, the present invention considers fault type mainly for route and bus.Wherein route
It include: three-phase shortcircuit, line to line fault ground connection, two-phase phase fault, single-phase short circuit, bus-bar fault consideration three-phase fault and single-phase event
Barrier, selects 188 N-1 failures, chooses 10 N-2 failures, do not consider the double above failure.
Step 1: obtaining PMU metric data, SCADA data and historical failure operation data, system is respectively saved when obtaining failure
Voltage, short circuit current, active power and the reactive loss of point need to handle mass data if considering to select all nodes, because
This selects some nodes being affected, and the present embodiment selects 30 historical failures (to include minor failure, be used only for solving ω
Weight), and list first three failure of each ranking.Wherein, the node of line ± 7% is got in voltage selection, and line is got in active power selection
Line 10% is got in the node of daily load rate, often selection, includes reactive loss in line loss, and line loss per unit regulation selects nothing in 3%-5%
Function loss becomes failure when getting over the node of line 3%.Using improved level Clouds theory, ω is solved1、ω2、ω3、ω4Weight.Such as
Shown in Fig. 2, U indicates index set, and U1, U2, U3, U4 are expressed as voltage, short circuit current active power and reactive loss, U
={ U1, U2, U3, U4 }, U1={ U11, U12, U13 }, U2={ U21, U22, U23 }, U3={ U31, U32, U33 }, U4=
{U41,U42,U43}
Table 3 { U11, U12, U13, U21, U22, U23, U31, U32, U33, U41, U42, U43 } weight
And then obtain { U1, U2, U3 } to U1, { U21, U22, U23 } to U2, { U31, U32, U33 } to U3 and U41, U42,
U43 } to the judgement square of U4 are as follows:
Table 4 { U11, U12, U13 } is to U1 judgment matrix
| U1 | U11 | U12 | U13 |
| U11 | 1 | (0.475,0.019,0.017) | (0.291,0.009,0.007) |
| U12 | (2.105,0.0842,0.0753) | 1 | (0.234,0.007,0.005) |
| U13 | (3.436,0.106,0.7912) | (4.274,0.128,0.0913) | 1 |
Table 5 { U21, U22, U23 } is to U2 judgment matrix
| U2 | U21 | U22 | U23 |
| U21 | 1 | (0.527,0.025,0.022) | (0.256,0.009,0.007) |
| U22 | (1.897,0.09,0.079) | 1 | (0.217,0.007,0.004) |
| U23 | (3.906,0.137,0.107) | (4.608,0.149,0.0849) | 1 |
Judgment matrix of the table 6 { U31, U32, U33 } to U3
| U3 | U31 | U32 | U33 |
| U31 | 1 | (0.534,0.021,0.021) | (0.262,0.008,0.004) |
| U32 | (1.873,0.074,0.074) | 1 | (0.204,0.004,0.003) |
| U33 | (3.817,0.117,0.058) | (4.608,0.149,0.0849) | 1 |
Judgment matrix of the table 7 { U41, U42, U43 } to U4
| U4 | U41 | U42 | U43 |
| U41 | 1 | (0.241,0.006,0.003) | (0.475,0.009,0.008) |
| U42 | (4.149,0.103,0.052) | 1 | (0.284,0.007,0.005) |
| U43 | (2.105,0.040,0.035) | (3.521,0.087,0.0620) | 1 |
Judgment matrix of the table 8 { U1, U2, U3, U4 } to U1
By using root method, weights omega is acquired1=0.091, ω2=0.202, ω3=0.275, ω4=0.431, CR
=0.092 < 0.1, by calculate branch parameters screening with sequence index, choose 120 failures formed crucial forecast failure collection into
Enter load margin screening and sequence step based on sensitivity.
Step 2: calculating the load margin of each node under failure, and select preceding 30 failures and be ranked up, is formed serious pre-
Think fault set, since failure is more, only selected part failure in following table.
Table 9 is sorted based on the load margin of sensitivity
| Node number | Load margin |
| (1,2) | 0.263 |
| (2,18) | 0.303 |
| (1,25) | 0.328 |
| (1,22) | 0.333 |
| (2,5) | 0.439 |
| (1.3) | 0.473 |
Step 3: being calculated based on PMU voltage stabilization: according to serious forecast failure obtained by second step first with load bus 6
Simulation analysis is carried out for institute's chord road 5-6,6-7,6-26, it is assumed that the node load active power and reactive power increase in proportion
Greatly, other load bus power remain unchanged, and mention the voltage stability index based on synchronized phasor to the present invention and emulate
Analysis, as a result as shown in Figure 7.This is because line transmission power increases, line voltage distribution loss is also increase accordingly, branch 6-7's
Voltage stability index value is as shown in Figure 8 with the situation of change of load growth rate: when an error occurs, the power of each node can also be sent out
Raw to change, when power increases, voltage indexes are constantly increasing, and the voltage stability of each branch is all constantly declining.It should
Index required branch relevant information in calculating process is easier to obtain, and combines the high density measurement technology of PMU, so that it is calculated
It is simple, convenient and rapid.Based on this, it is as follows to form forecast failure collection:
The forecast failure collection screening and ranking results that 10 three-level of table is coordinated
| Node number | Fault type | Voltage stability index |
| (1,2) | Three-phase shortcircuit | 1.351 |
| (1,18) | Three-phase shortcircuit | 1.023 |
| (2,18) | Three-phase shortcircuit | 0.975 |
| (2,3) | Three-phase shortcircuit | 0.943 |
| (1,25) | Three-phase shortcircuit | 0.923 |
| (2,25) | Three-phase shortcircuit | 0.919 |
| (1,22) | Three-phase shortcircuit | 0.903 |
| (2,22) | Three-phase shortcircuit | 0.887 |
| (18,25) | Three-phase shortcircuit | 0.869 |
| (18,22) | Three-phase shortcircuit | 0.861 |
Above as can be seen that coordinating forecast failure screening by three-level and sorting to show that the extent of injury of N-2 failure is remote
Greater than N-1 failure, it is contemplated that contain whole N-2 failures in fault set, this method is there is no there is a situation where leaking to select, and energy is very well
Influence of the reaction failure to system.It follows that being directed to the Contingency screening and ranking of three-level coordination as a result, can accurately export
The relatively major break down of power distribution network safe and stable operation is influenced, and then final system fault set can be obtained.According to the system failure of acquisition
The type and severity of collection can further be taken and arrange for the reply maintenance measure of system difference severity failure or protection
It applies, and helps to improve distribution network system and cope with the ability of various failures and the ability of power distribution network anticipation failure.
In summary: present example is screened using the forecast failure collection that three-level is coordinated and sort method, passes through and proposes branch
Road parameter index simultaneously solves weight with improved level Clouds theory, is ranked up from big to small to SL, completes forecast failure collection
Prescreening calculate the load margin of each node after failure it is further proposed that the load margin index based on sensitivity, according to negative
Lotus margin value sorts from small to large, finally constructs the voltage stabilization screening index based on synchronized phasor, calculates failure and reaches node electricity
Stationary value is pressed, is sorted from large to small according to voltage stabilization value, forecast failure collection is formed and is exported through output unit.It can be seen by table 10
Out, N-2 failure is larger to systematic influence.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any
The staff for being familiar with the art in the technical scope disclosed by the present invention, can readily occur in various equivalent modifications or replace
It changes, these modifications or substitutions should be covered by the protection scope of the present invention.Therefore, protection scope of the present invention should be with right
It is required that protection scope subject to.
Claims (8)
1. forecast failure screening and sort method that a kind of three-level is coordinated, which is characterized in that this method includes the following steps:
1) various operation metric data when acquisition distribution network failure, fault data, establish fault history metric data library；
2) fault data provided according to step 1) establishes branch parameters screening and sequence index, bearing based on sensitivity respectively
Voltage stabilization screening of the lotus nargin screening with sequence index, based on synchronized phasor and sequence index, and by coordinating progressive sieve
Mode is selected successively to carry out branch parameters screening and sequence, load margin screening and sequence and voltage stabilization screening and sequence, it is real
Existing forecast failure quick and precisely screens；
3) the serious forecast failure of influence system safe and stable operation is exported.
2. forecast failure screening and sort method that a kind of three-level according to claim 1 is coordinated, which is characterized in that step
2) specifically includes the following steps:
201) the initial forecast failure collection in fault data historical metrology data library provided according to step 1)；
202) branch parameters screening and sequence index are established；
203) it is screened and the index selection key forecast failure set that sorts according to branch parameters；
204) load margin screening and sequence index based on sensitivity are established；
205) it is screened and the serious forecast failure set of index selection that sorts according to load margin；
206) voltage stabilization screening and sequence index based on synchronized phasor are established；
207) fault set screening and sequence are carried out in conjunction with serious forecast failure according to crucial forecast failure set.
3. forecast failure screening and sort method that a kind of three-level according to claim 2 is coordinated, which is characterized in that establish
The particular content of branch parameters screening and sequence index are as follows:
Using the operation data of fault moment power distribution network branch by normalized, preliminary screening is carried out to forecast failure collection,
Obtain the weight relationship under fault condition between voltage, short circuit current, active power and reactive loss.
4. forecast failure screening and sort method that a kind of three-level according to claim 3 is coordinated, which is characterized in that for
Branch L, the weight relationship between voltage, short circuit current, active power and reactive loss are as follows:
In formula: SLFor branch parameters voltage indexes, VL、IL、PL、ΔQLThe respectively voltage of branch L, short circuit current, active power
And reactive loss, ω1、ω2、ω3、ω4Respectively voltage, short circuit current, active and reactive loss weight coefficient.
5. forecast failure screening and sort method that a kind of three-level according to claim 4 is coordinated, which is characterized in that use
Improved level Clouds theory method obtains the weight under fault condition between voltage, short circuit current, active power and reactive loss
Coefficient.
6. forecast failure screening and sort method that a kind of three-level according to claim 1 is coordinated, which is characterized in that obtain
The calculating formula of branch parameters screening and sequence index are as follows:
Wherein:
7. forecast failure screening and sort method that a kind of three-level according to claim 1 is coordinated, which is characterized in that utilize
Load margin screening index based on sensitivity to the lesser Contingency screening of failure afterload nargin and sorts, particular content are as follows:
If the parametrization power flow equation of system are as follows:
In formula: x ∈ RnIt is system state variables vector, such as node current amplitude and phase angle；λ ∈ R is load parameter；p∈RMFor
Parameter vector, f () are that n ties up power flow equation；H () is One Dimensional Parameter equation, and in voltage collapse point, various parameters are to stabilization
The calculation formula of the sensitivity of margin index are as follows:
In formula: w is a row vector at system voltage collapse point, " |*" indicate the value at bifurcation point；
For fault branch L, the changing value of stability margin is indicated with following formula:
In formula:Qg,iRespectively generator active power and reactive power output valve；Respectively generator failure
When sensitivity of the stability margin to active and idle output valve, Ωk.pCompensated dynamo set under the conditions of expression failure K, wherein mending
Generator j is repaid for stability margin Δ λjIt is obtained using following formula:
In formula: Ωk.IFor fault generator set, Ωk.TFor fault branch set；λ0It is the stability margin of system before failure；It obtains
Stability margin Δ λjIt sorts from small to large according to load margin afterwards.
8. forecast failure screening and sort method that a kind of three-level according to claim 7 is coordinated, which is characterized in that establish
Voltage stabilization screening and the particular content of sequence index based on synchronized phasor are as follows:
Obtain Line Flow formula:
Vjcosθ-ViVjcos(θ-δ)+PjZ=0
In formula: PjFor active power at node j, Vi、VjVoltage magnitude respectively at i, j, Z are the equivalent impedance of route, θ
For the impedance angle of route, δ is node voltage differential seat angle；
By above formula to VjDerivation:
It arranges:
According to P-V curve it is found that meeting following relationship in collapse of voltage point:
Then have:
System is when operating normally:
Therefore it is as follows to define voltage stability index:
The normal variation range of the index is 0 < Ev< 1, in Voltage Instability critical point Ev=1, for whole system, definition electricity
Press stability index as follows:
Ev=Ev,ij=max { Ev1,…,Evn}
It is based on the screening of synchronized phasor voltage stabilization and the index that sorts by whole system of index maximum value, according to the index size pair
Catastrophe failure is ranked up.
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| CN113378901A (en) * | 2021-05-31 | 2021-09-10 | 国网上海市电力公司 | Active power distribution network expected fault set screening method based on KFCM cluster analysis and PMU device |
| CN113722657A (en) * | 2021-08-12 | 2021-11-30 | 国网河北省电力有限公司保定供电分公司 | Transformer reactance optimization method and device and transformer |
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