CN108711851A - A method of assessment medium voltage distribution network Loop Closing Operation safety - Google Patents
A method of assessment medium voltage distribution network Loop Closing Operation safety Download PDFInfo
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- CN108711851A CN108711851A CN201810568104.0A CN201810568104A CN108711851A CN 108711851 A CN108711851 A CN 108711851A CN 201810568104 A CN201810568104 A CN 201810568104A CN 108711851 A CN108711851 A CN 108711851A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
Abstract
The present invention discloses a kind of method of assessment medium voltage distribution network Loop Closing Operation safety, including：Topological structure, device parameter and the real-time running data for obtaining cyclization network carry out state estimation to high voltage distribution network, obtain the voltage magnitude and phase angle of cyclization feeder line head end 10kV busbares；It chooses the ratio between the active and reactive power of active and reactive load with feeder line head end of each load point on cyclization feeder line and is used as input variable, each rank cumulant of input variable is calculated based on historical load data；Being determined property trend and Alloy White Iron calculate；Calculate each rank cumulant of Alloy White Iron；Seek the cumulative probability distribution of Alloy White Iron；The out-of-limit probability for calculating each Alloy White Iron, assesses the safety of Loop Closing Operation.The present invention can qualitative assessment medium voltage distribution network Loop Closing Operation safety；Solve the problems, such as that each load point real-time load data of feeder line can not obtain in practice；Also solve the problems, such as that conventional numeric method needs the probability-distribution function of known input variable when seeking cumulant.
Description
Technical field
The present invention relates to power system security stable operation field, more particularly to a kind of assessment medium voltage distribution network Loop Closing Operation
The method of safety.
Background technology
Medium voltage distribution network is using closed loop design, the powering mode of open loop operation.Under normal circumstances, interconnection switch is opened, and is matched
Power grid is run in irradiation structure；When overhaul of the equipments or accident treatment, it can not be had a power failure by the realization of the Loop Closing Operation of interconnection switch and be turned
Move load.The Loop Closing Operation of medium voltage distribution network may generate larger Alloy White Iron in cyclization network, cause line current
Protection act or certain electric equipment overloads, lead to larger range of power outage.Therefore, operations staff needs before Loop Closing Operation
Its safety is assessed.
Do not have systematic medium voltage distribution network Loop Closing Operation security assessment method still at present, staff is logical in actually producing
Often rule of thumb think that the Loop Closing Operation of following situations is safe：
(1) the 10kV busbar voltage difference in magnitude of feeder line where the fracture of interconnection switch both sides is less than 10% before cyclization；
(2) feeder load difference in interconnection switch both sides is smaller before cyclization, and transmission of the total load no more than any feeder line is held
Measure the upper limit；
Therefore, it is to ensure safety, the cyclization of medium voltage distribution network is fallen load operation and carried out mostly at load lighter night.
However, this appraisal procedure based on knowhow lacks corresponding theory support.Theoretical analysis shows that Alloy White Iron
Size be affected with phase angle difference by the voltage amplitude value difference of interconnection switch fracture both sides.Therefore, according only to cyclization point both sides
The safety evaluation that the voltage amplitude value difference of 10kV busbares carries out Loop Closing Operation is a lack of scientific basis.In addition, by comparing closing
The method of ring feeder line total load and line transmission maximum size will cause cyclization safety evaluation result more conservative, to final
The reference value of cyclization decision-making is limited.
There is correlative study to propose to carry out cyclization peace by the calculating of involutive ring steady-state current and transient shock current at present
Full property assessment.But since the configuration of existing power distribution network measuring equipment is limited in scope, the voltage of 10kV busbares in power distribution network can not be obtained
Phase angle information and the voltage magnitude and phase angle difference of interconnection switch fracture both sides calculate each on the feeder line needed for Alloy White Iron in addition
Load point real-time load data can not also obtain, and the practicability that these are studied is caused to be restricted.
Invention content
The object of the present invention is to provide a kind of methods of assessment medium voltage distribution network Loop Closing Operation safety, in power distribution network
The problem of voltage phase angle data of each busbar can not obtain uses and carries out the method for state estimation to high voltage distribution network to obtain mother
Line phase angle information.The problem of required feeder load point real-time load data can not obtain, first base are calculated for Alloy White Iron
The probability density characteristics of each load point load value are analyzed in historical load data, then theoretical based on Probabilistic Load Flow, is become using half step
Amount method seeks the integral distribution curve of Alloy White Iron, finally by the safety sought the out-of-limit probability of Alloy White Iron and operated with involutive ring
Property is assessed.
In order to achieve the above object, the invention discloses it is a kind of assessment medium voltage distribution network Loop Closing Operation safety method,
Load point load on cyclization feeder line is considered as stochastic variable by this method, based on Probabilistic Load Flow theory seek cyclization steady-state current with
The safety of out-of-limit probability and the involutive ring operation of transient shock current is assessed, and is comprised the steps of：
Real-time running data before S1, the topological structure for obtaining cyclization network, device parameter and cyclization, to high voltage distribution network
State estimation is carried out, the voltage magnitude and phase angle of two cyclization feeder line head end 10kV busbares are obtained；
S2, the ratio between the burden with power of each load point and the active power of feeder line head end and cyclization feedback on cyclization feeder line are chosen
The ratio between the load or burden without work of each load point and the reactive power of feeder line head end are used as input variable, the history based on each load point on line
Load data calculates each rank cumulant of each input variable within the season and period where the cyclization moment；
S3, being determined property Load flow calculation and Alloy White Iron calculate at benchmark operating point, obtain cyclization network system shape
State variable a reference value, Alloy White Iron a reference value and transition matrix；
S4, each rank cumulant that Alloy White Iron is calculated according to each rank cumulant of input variable and transition matrix；
S5, the cumulative probability distribution that Alloy White Iron is sought according to each rank cumulant of Alloy White Iron；
S6, using the maximum allowable current-carrying capacity of feeder line and current protection setting valve as limit value, calculate each Alloy White Iron
Out-of-limit probability, and the safety of involutive ring operation is assessed.
Preferably, the step S1 is further included：
The state estimation that high voltage distribution network is carried out using weighted least-squares criterion, obtains two cyclization feeder line head end 10kV
The voltage magnitude and phase angle of busbar, while bad metric data can be identified and be corrected.
Preferably, the step S2 is further included：
The load value of each load point is considered as stochastic variable, chooses the active of the burden with power of each load point and feeder line head end
The ratio between the load or burden without work of each load point and the reactive power of feeder line head end are used as input variable on power ratio and cyclization feeder line
Probabilistic load flow is carried out, and each rank cumulant of input variable is sought based on historical load data.
The method for being preferably based on each rank cumulant that historical load data seeks input variable includes following procedure：
If input variable kPIt is the ratio between burden with power and the feeder line head end active power of any one load point；From the load
For point with 96 daily load historical datas of whole year of this outlet, arrangement obtains the whole year discrete measured data of the input variable,
And it builds for seeking input variable kPEach rank cumulant sample set S；
Sample set S is divided into several subsample collection by season and period, by the analysis to any one subsample collection,
Seek input variable kPEach rank cumulant within the season and period where the cyclization moment；
If cyclization moment corresponding subsample is concentrated with N number of discrete historical data { kP1,kP2,kP3,…,kPN, it calculates first
Its each rank moment of the orign αv：
Again by the relationship of cumulant and moment of the orign, its each rank cumulant γ is calculatedv：
Wherein, α1And αjRespectively v=1, v=j when moment of the orign；To take different groups of j element from v element
Close number.
Preferably, the step S3 is further included：
If interconnection switch fracture both sides voltage difference isCyclization loop total impedance is Z∑, then cyclization stable state circulationFor：
IfWithThe respectively initial current of the preceding both sides feeder line head end of cyclization, X=[θ1,V1,θ2,V2,…,θn,Vn]TFor
Cyclization network system situation variable, according to superposition theorem, both sides feeder line head end steady-state current virtual value I after cyclization1'And I'2Respectively
For：
If I1And I2RespectivelyWithVirtual value, the most favourable opposition that both sides feeder line head end occurs in the transient process of cyclization
Hit current effective value I1MAnd I2MRespectively：
I1M=I1+1.51Ic=g3(X) (6)
I2M=I2+1.51Ic=g4(X) (7)
If Z=[I1',I'2,I1M,I2M]TFor Alloy White Iron variable, then Alloy White Iron equation is：
Z=g (X) (8)
If K is the input variable of probabilistic load flow；W indicates the injecting power of each node in cyclization network system, then W=
AK, wherein A are the diagonal matrix being made of two feeder line head end active power and reactive power；Cyclization network system power flow equation can
It is expressed as：
W=f (X) (9)
Input variable K is stochastic variable, is represented by K0+ Δ K, wherein K0It is cyclization net for the desired value of stochastic variable K
Network system benchmark operating point；Δ K is random perturbation；Cyclization network system situation variable X is represented by X0+ Δ X, X0For cyclization net
Network system state variables desired value, Δ X are random perturbation；Each node injecting power W is represented by W0+ Δ W, W0It is injected for node
Power desired value, Δ W are the random perturbation of corresponding Δ X；Alloy White Iron variable Z is represented by Z0+ Δ Z, Z0For Alloy White Iron variable
Desired value, Δ Z are the random perturbation of corresponding Δ X；
Cyclization network system power flow equation (9) and Alloy White Iron equation (8) are subjected to Taylor series expansion and omit high order
, obtain the linear relationship between Δ Z and Δ K：
Wherein, Jacobian matrixCoefficient matrix
Preferably, the step S3 also includes：First in benchmark operating point K0Place is based on formula (9) being determined property trend
It calculates, obtains cyclization network system situation variable X0And Jacobian matrix J0, wherein W0=AK0；Then in X0Place by formula (8) into
Row Alloy White Iron calculates, and obtains Alloy White Iron variable Z0And coefficient matrix G0；Finally obtain transition matrix T0。
Preferably, the step S4 is further included：If Δ K(v)Indicate the v rank cumulant of input variable,It indicates
T0The coefficient matrix that the v power of middle each element is constituted, then by the property of cumulantAcquire cyclization electricity
The v rank cumulant Δs Z of flow variables(v)。
Preferably, the step S5 is further included：The accumulation of Alloy White Iron is sought using Cornish-Fisher series
Probability distribution, method are as follows：
If the cumulative distribution function of Alloy White Iron variable Z is F (z), Standard Normal Distribution is Φ (z), F (z) and Φ
(z) α quantiles can be expressed as z (α) andThat is z (α)=F-1(α),Then z (α) andMeet following relationship：
Wherein, gvFor Alloy White Iron variable Z v ranks standardize cumulant, if the v rank cumulant of stochastic variable Z is
γv, standard deviation σ, thenCan it can be acquired by each rank cumulant of Alloy White Iron by formula (11)
Cumulative distribution function.
Preferably, the step S6 is further included：
Alloy White Iron variable Z includes the steady-state current virtual value I of both sides feeder line head end after cyclization1'And I'2And both sides feedback
The maximum impact current effective value I that line head end occurs1MAnd I2M；
If variable I1'、I'2、I1M、I2MCumulative distribution function be respectively F1(x)、F2(x)、F3(x)、F4(x), cyclization point
Feeder line maximum allowable current-carrying capacity in both sides is respectively Imax,1And Imax,2, electric current I sections of both sides protection seting value is respectively IsetI,1With
IsetI,2, then the out-of-limit probability of each Alloy White Iron be respectively：
P1=P (I1'≥Imax,1)=1-F1(Imax,1)
P2=P (I'2≥Imax,2)=1-F2(Imax,2)
P3=P (I1M≥IsetI,1)=1-F3(IsetI,1)
P4=P (I2M≥IsetI,2)=1-F4(IsetI,2)
According to the safety of the size qualitative assessment medium voltage distribution network Loop Closing Operation of the out-of-limit probability of each Alloy White Iron：If more
Limit probability is respectively less than 5%, then assert that the safety of Loop Closing Operation is higher, otherwise assert that the safety of this Loop Closing Operation cannot obtain
Ensure.
Compared with prior art, beneficial effects of the present invention are：
(1) calculating for the cyclization steady-state current and transient shock current that the present invention is generated by involutive ring operation, can come
The safety of qualitative assessment medium voltage distribution network Loop Closing Operation, and assessment result has theoretical foundation and can be the cyclization of operations staff
Operation provides reference.
(2) present invention seeks closing using the load point load on cyclization feeder line as stochastic variable based on Probabilistic Load Flow theory
The probability density characteristics of ring steady-state current and transient shock current, solving current each load point real-time load data can not obtain
The problem of.
(3) each rank cumulant of the invention by seeking input variable to the analysis of historical load data, solves biography
Numerical method of uniting needs the problem of probability-distribution function of known input variable when seeking cumulant.
Description of the drawings
The schematic diagram of the medium voltage distribution network Loop Closing Operation of Fig. 1 present invention；
The Technology Roadmap of the medium voltage distribution network Loop Closing Operation security assessment method of Fig. 2 present invention.
Specific implementation mode
The invention discloses a kind of methods of assessment medium voltage distribution network Loop Closing Operation safety, in order to keep the present invention brighter
Aobvious understandable, below in conjunction with the drawings and specific embodiments, the present invention will be further described.
As shown in Figure 1, system power transmission network (220kV and above power grid) structure operation annular in shape, 110kV and with
The power distribution network open loop operation of lower voltage class.Q1 and Q2 is respectively the outlet breaker of interconnection switch both sides feeder line.Two 10kV
It is connected by interconnection switch Q3 between feeder line；When systems are functioning properly, interconnection switch Q3 is disconnected；When the method for operation adjustment or
It can be closed interconnection switch Q3 when emergency episode processing, carrying out load heat by cyclization turns over.
As shown in Fig. 2, the method for assessment medium voltage distribution network Loop Closing Operation safety provided by the invention is divided into 6 main steps
Suddenly, as follows：
Step A, high voltage distribution network state estimation；
In step, before obtaining the topological structure of cyclization network, device parameter and cyclization real-time running data base
On plinth, state estimation is carried out to high voltage distribution network, obtains the voltage magnitude and phase angle of two cyclization feeder line head end 10kV busbares.
Specifically：
When being calculated due to underway press-fitting power grid Alloy White Iron, general cyclization feeder line head end 10kV bus nodes of choosing are made
For reference mode, therefore need the voltage magnitude and phase angle of known contact switch both sides 10kV busbares.The amount of medium voltage distribution network at present
Examining system can collect voltage magnitude, however its phase angle information can not still obtain.In view of this, the power transmission network in obtaining cyclization network
On the basis of real-time running data before the topological structure, device parameter and cyclization of high voltage distribution network, using weighting minimum two
Multiply the state estimation that criterion (WLS, Weighted Least Squares) carries out high voltage distribution network, the weighted least-squares method
Have the advantages that model is simple, calculation amount is small.So by the state estimation of high voltage distribution network, cyclization feeder line head end can be obtained
The voltage magnitude and phase angle of 10kV busbares, while bad metric data can also be identified and be corrected.
Step B, each rank cumulant of input variable is calculated；
In stepb, choose on cyclization feeder line the ratio between active power of burden with power and the feeder line head end of each load point with
And the ratio between the load or burden without work of each load point and the reactive power of feeder line head end are used as input variable on cyclization feeder line, are based on each load
96 daily load historical datas of whole year of point calculate each rank of each input variable within the season and period where the cyclization moment half
Invariant.
Specifically, before medium voltage distribution network Loop Closing Operation, the real-time load of each load point is generally difficult to obtain.In view of this,
The load value of each load point is considered as stochastic variable, and choose the burden with power of each load point and feeder line head end active power it
Than and cyclization feeder line on each load point the ratio between the reactive power of load or burden without work and feeder line head end carried out as input variable it is general
Rate Load flow calculation.In each rank cumulant for seeking input variable, traditional method is the probability-distribution function according to variable,
It is sought using numerical method.However the distribution function of these input variables is unknown in engineering.It is based on going through for this purpose, the present invention uses
The method that history load data seeks each rank cumulant of input variable, this method are described as follows：
If input variable kPIt is the ratio between burden with power and the feeder line head end active power of some load point.From the load point with
In 96 daily load historical datas of whole year of this outlet, arranges and obtain the whole year discrete measured data of the input variable, and structure
It builds for seeking input variable kPEach rank cumulant sample set S.In view of load is in Various Seasonal, daily different periods
Different characteristics may be presented, sample set S is pressed into season (spring, summer, autumn, winter) and period (00:00-08:00,08:00-18:00,
18:00-24:00) it is divided into a sub- sample set (S of 12 (4 × 3=12)1, S2..., S12).By the analysis to some subsample collection,
Seek input variable kPEach rank cumulant within the season and period where the cyclization moment.
If cyclization moment corresponding subsample is concentrated with N number of discrete historical data, it is represented by { kP1,kP2,kP3,…,
kPN}.Its each rank moment of the orign α is calculated firstv：
Again by the relationship of cumulant and moment of the orign, its each rank cumulant γ is calculatedv：
Wherein,To take the various combination number of j element from v element；α1And αjRespectively v=1, v=j when original
Point square.
Step C, certainty Load flow calculation is calculated with Alloy White Iron；
In step C, in conjunction with the topology information and operation data of cyclization network, the being determined property tide at benchmark operating point
Stream calculation and Alloy White Iron calculate, and obtain cyclization network system situation variable a reference value, Alloy White Iron a reference value and coefficient square
Battle array.
Specifically, if interconnection switch fracture both sides voltage difference isCyclization loop total impedance is Z∑, then cyclization stable state ring
StreamFor：
IfWithThe respectively initial current of the preceding both sides feeder line head end of cyclization, X=[θ1,V1,θ2,V2,…,θn,Vn]TFor
Cyclization network system situation variable, according to superposition theorem, both sides feeder line head end steady-state current virtual value I after cyclization1'And I'2Respectively
For：
If I1And I2RespectivelyWithVirtual value, both sides feeder line head end is likely to occur most in the transient process of cyclization
Large inrush current virtual value I1MAnd I2MRespectively：
I1M=I1+1.51Ic=g3(X) (6)
I2M=I2+1.51Ic=g4(X) (7)
If Z=[I1',I'2,I1M,I2M]TFor Alloy White Iron variable, then Alloy White Iron equation is：
Z=g (X) (8)
If K is the input variable of probabilistic load flow, active, the nothing of the active and reactive and circuit head end of each node are indicated
The ratio between work(；W indicates the injecting power of each node in cyclization network system, then W=AK, wherein A be by two feeder line head ends it is active and
The diagonal matrix of idle composition.Cyclization network system power flow equation is represented by：
W=f (X) (9)
Input variable K is stochastic variable, is represented by K0+ Δ K, wherein K0It is cyclization net for the desired value of stochastic variable K
Network system benchmark operating point, Δ K are random perturbation.Similarly, cyclization network system situation variable X is represented by X0+ Δ X, X0To close
Ring network system state variable desired value, Δ X are random perturbation.Each node injecting power W is represented by W0+ Δ W, W0For node
Injecting power desired value, Δ W are the random perturbation of corresponding Δ X.Alloy White Iron variable Z is represented by Z0+ Δ Z, Z0For Alloy White Iron
Variable desired value, Δ Z are the random perturbation of corresponding Δ X.
Cyclization network system power flow equation (9) and Alloy White Iron equation (8) are subjected to Taylor series expansion and omit high order
, obtain the linear relationship between Δ Z and Δ K：
Wherein, Jacobian matrixCoefficient matrix
In step C, first in benchmark operating point K0Locate (W at this time0=AK0) based on formula (9) being determined property trend
It calculates, obtains cyclization network system situation variable X0And Jacobian matrix J0；Then in X0Place carries out Alloy White Iron by formula (8)
It calculates, obtains Alloy White Iron variable Z0And coefficient matrix G0；Finally obtain transition matrix T0。
Step D, each rank cumulant of Alloy White Iron is calculated；
In step D, the transition matrix meter that each rank cumulant and step C of the input variable obtained by step B obtain
Calculate each rank cumulant of Alloy White Iron.
Specifically, each rank cumulant for having sought obtaining input variable in stepb, if Δ K(v)Indicate input variable
V rank cumulant,Indicate T0The coefficient matrix that the v power of middle each element is constituted, then can be constant by half in step D
The property of amountAcquire the v rank cumulant Δs Z of Alloy White Iron variable(v)。
Step E, the probability distribution of each Alloy White Iron is sought；
In step E, using Cornish-Fisher series expansion methods, sought by each rank cumulant of Alloy White Iron
The cumulative probability of Alloy White Iron is distributed.
Specifically, the side of the cumulative probability distribution of Alloy White Iron is sought in step E using Cornish-Fisher series
Method is as follows：
If the cumulative distribution function of certain Alloy White Iron variable Z be F (z), Standard Normal Distribution be Φ (z), F (z) and
The α quantiles of Φ (z) can be expressed as z (α) andThat is z (α)=F-1(α),Then z (α) andMeet following relationship：
Wherein, gvFor the v ranks normalization cumulant of Alloy White Iron variable Z, the v rank cumulant of even stochastic variable Z
For γv, standard deviation σ, then
Its cumulative distribution function can be acquired by each rank cumulant of Alloy White Iron by formula (11).
Step F, the out-of-limit probability of each Alloy White Iron is assessed；
In step F, according to safe cyclization condition, respectively by the maximum allowable current-carrying capacity of feeder line and current protection setting valve
As limit value, the out-of-limit probability of each Alloy White Iron is calculated, and the safety of involutive ring operation is assessed.
Specifically, Alloy White Iron variable Z includes：The steady-state current virtual value I of both sides feeder line head end after cyclization1'And I'2With
And the maximum impact current effective value I that both sides feeder line head end is likely to occur1MAnd I2M.If variable I1'、I'2、I1M、I2MIterated integral
Cloth function is respectively F1(x)、F2(x)、F3(x)、F4(x), feeder line maximum allowable current-carrying capacity in cyclization point both sides is respectively Imax,1With
Imax,2, electric current I sections of both sides protection seting value is respectively IsetI,1And IsetI,2, then the out-of-limit probability of each Alloy White Iron be respectively：
P1=P (I1'≥Imax,1)=1-F1(Imax,1)
P2=P (I'2≥Imax,2)=1-F2(Imax,2)
P3=P (I1M≥IsetI,1)=1-F3(IsetI,1)
P4=P (I2M≥IsetI,2)=1-F4(IsetI,2)
Finally, according to the size of above four kinds of out-of-limit probability can qualitative assessment medium voltage distribution network Loop Closing Operation safety：
It is respectively less than if 5% if out-of-limit probability it is believed that the safety of Loop Closing Operation is higher, otherwise it is assumed that the safety of this Loop Closing Operation is not
It can be guaranteed, it is proposed that consider further that cyclization after carrying out corresponding method of operation adjustment.
In conclusion the present invention provides a kind of method of assessment medium voltage distribution network Loop Closing Operation safety, pass through calculating
The safety of cyclization steady-state current and the operation of the out-of-limit probability involutive ring of transient shock current carries out qualitative assessment, solves reality
In each load point real-time load data the problem of can not obtaining.It applies this method in actual production, it can be fast before cyclization
The safety of fast ground involutive ring operation is effectively assessed, and is formulated cyclization decision for operations staff and provided support.
Although present disclosure is discussed in detail by above preferred embodiment, but it should be appreciated that above-mentioned
Description is not considered as limitation of the present invention.After those skilled in the art have read the above, for the present invention's
A variety of modifications and substitutions all will be apparent.Therefore, protection scope of the present invention should be limited to the appended claims.
Claims (9)
1. a kind of method of assessment medium voltage distribution network Loop Closing Operation safety, which is characterized in that this method will be on cyclization feeder line
Load point load is considered as stochastic variable, and the out-of-limit general of cyclization steady-state current and transient shock current is sought based on Probabilistic Load Flow theory
The safety of rate and involutive ring operation is assessed, and is comprised the steps of：
Real-time running data before S1, the topological structure for obtaining cyclization network, device parameter and cyclization, carries out high voltage distribution network
State estimation obtains the voltage magnitude and phase angle of two cyclization feeder line head end 10kV busbares；
S2, it chooses on cyclization feeder line on the ratio between active power of burden with power and the feeder line head end of each load point and cyclization feeder line
The ratio between the load or burden without work of each load point and the reactive power of feeder line head end are used as input variable, the historical load based on each load point
Data calculate each rank cumulant of each input variable within the season and period where the cyclization moment；
S3, being determined property Load flow calculation and Alloy White Iron calculate at benchmark operating point, obtain the change of cyclization network system situation
Measure a reference value, Alloy White Iron a reference value and transition matrix；
S4, each rank cumulant that Alloy White Iron is calculated according to each rank cumulant of input variable and transition matrix；
S5, the cumulative probability distribution that Alloy White Iron is sought according to each rank cumulant of Alloy White Iron；
S6, using the maximum allowable current-carrying capacity of feeder line and current protection setting valve as limit value, calculate the out-of-limit of each Alloy White Iron
Probability, and the safety of involutive ring operation is assessed.
2. a kind of method of assessment medium voltage distribution network Loop Closing Operation safety as described in claim 1, which is characterized in that
The step S1 is further included：
The state estimation that high voltage distribution network is carried out using weighted least-squares criterion, obtains two cyclization feeder line head end 10kV busbares
Voltage magnitude and phase angle, while bad metric data can be identified and be corrected.
3. a kind of method of assessment medium voltage distribution network Loop Closing Operation safety as described in claim 1, which is characterized in that
The step S2 is further included：
Choose the nothing of each load point on the ratio between the burden with power of each load point and the active power of feeder line head end and cyclization feeder line
The ratio between workload and the reactive power of feeder line head end carry out probabilistic load flow as input variable, and are based on historical load data
To seek each rank cumulant of input variable.
4. a kind of method of assessment medium voltage distribution network Loop Closing Operation safety as claimed in claim 3, which is characterized in that
The method that each rank cumulant of input variable is sought based on historical load data includes following procedure：
If input variable kPIt is the ratio between burden with power and the feeder line head end active power of any one load point；From the load point with
In 96 daily load historical datas of whole year of this outlet, arranges and obtain the whole year discrete measured data of the input variable, and structure
It builds for seeking input variable kPEach rank cumulant sample set S；
Sample set S is divided into several subsample collection by season and period to seek by the analysis to any one subsample collection
Input variable kPEach rank cumulant within the season and period where the cyclization moment；
If cyclization moment corresponding subsample is concentrated with N number of discrete historical data { kP1,kP2,kP3,…,kPN, it is each that it is calculated first
Rank moment of the orign αv：
Again by the relationship of cumulant and moment of the orign, its each rank cumulant γ is calculatedv：
Wherein, α1And αjRespectively v=1, v=j when moment of the orign；To take the various combination of j element from v element
Number.
5. a kind of method of assessment medium voltage distribution network Loop Closing Operation safety as claimed in claim 4, which is characterized in that
The step S3 is further included：
If interconnection switch fracture both sides voltage difference isCyclization loop total impedance is Z∑, then cyclization stable state circulationFor：
IfWithThe respectively initial current of the preceding both sides feeder line head end of cyclization, X=[θ1,V1,θ2,V2,…,θn,Vn]TFor cyclization
Network system situation variable, according to superposition theorem, both sides feeder line head end steady-state current virtual value I&apos after cyclization;1And I'2Respectively：
If I1And I2RespectivelyWithVirtual value, the maximum impact electric current that both sides feeder line head end occurs in the transient process of cyclization
Virtual value I1MAnd I2MRespectively：
I1M=I1+1.51Ic=g3(X) (6)
I2M=I2+1.51Ic=g4(X) (7)
If Z=[I'1,I'2,I1M,I2M]TFor Alloy White Iron variable, then Alloy White Iron equation is：
Z=g (X) (8)
If K is the input variable of probabilistic load flow；W indicates the injecting power of each node in cyclization network system, then W=AK,
Wherein A is the diagonal matrix being made of two feeder line head end active power and reactive power；Cyclization network system power flow equation can table
It is shown as：
W=f (X) (9)
Input variable K is stochastic variable, is represented by K0+ Δ K, wherein K0It is cyclization network system for the desired value of stochastic variable K
System benchmark operating point；Δ K is random perturbation；Cyclization network system situation variable X is represented by X0+ Δ X, X0For cyclization network system
System state variable desired value, Δ X are random perturbation；Each node injecting power W is represented by W0+ Δ W, W0For node injecting power
Desired value, Δ W are the random perturbation of corresponding Δ X；Alloy White Iron variable Z is represented by Z0+ Δ Z, Z0It is expected for Alloy White Iron variable
Value, Δ Z are the random perturbation of corresponding Δ X；
Cyclization network system power flow equation (9) and Alloy White Iron equation (8) are subjected to Taylor series expansion and omit high-order term, is obtained
Linear relationship between Δ Z and Δ K：
Wherein, Jacobian matrixCoefficient matrix
6. a kind of method of assessment medium voltage distribution network Loop Closing Operation safety as claimed in claim 5, which is characterized in that
The step S3 also includes：First in benchmark operating point K0Place obtains cyclization by formula (9) being determined property Load flow calculation
Network system situation variable X0And Jacobian matrix J0, wherein W0=AK0；Then in X0Place carries out Alloy White Iron by formula (8)
It calculates, obtains Alloy White Iron variable Z0And coefficient matrix G0；Finally obtain transition matrix T0。
7. a kind of method of assessment medium voltage distribution network Loop Closing Operation safety as claimed in claim 6, which is characterized in that
The step S4 is further included：If Δ K(v)Indicate the v rank cumulant of input variable,Indicate T0Middle each element
The coefficient matrix that v power is constituted, then by the property of cumulantAcquire the v ranks of Alloy White Iron variable
Cumulant Δ Z(v)。
8. a kind of method of assessment medium voltage distribution network Loop Closing Operation safety as claimed in claim 7, which is characterized in that
The step S5 is further included：The cumulative probability distribution of Alloy White Iron, side are sought using Cornish-Fisher series
Method is as follows：
If the cumulative distribution function of Alloy White Iron variable Z is F (z), Standard Normal Distribution is Φ (z), F (z) and Φ (z)
α quantiles can be expressed as z (α) andThat is z (α)=F-1(α),Then z (α) andMeet
Following relationship：
Wherein, gvFor Alloy White Iron variable Z v ranks standardize cumulant, if the v rank cumulant of stochastic variable Z be γv, mark
Quasi- difference is σ, thenCan its cumulative probability be acquired by each rank cumulant of Alloy White Iron by formula (11)
Distribution function.
9. a kind of method of assessment medium voltage distribution network Loop Closing Operation safety as claimed in claim 8, which is characterized in that
The step S6 is further included：
Alloy White Iron variable Z includes the steady-state current virtual value I&apos of both sides feeder line head end after cyclization;1And I'2And both sides feeder line is first
Hold the maximum impact current effective value I occurred1MAnd I2M；
If variable I'1、I'2、I1M、I2MCumulative distribution function be respectively F1(x)、F2(x)、F3(x)、F4(x), cyclization point both sides are presented
The maximum allowable current-carrying capacity of line is respectively Imax,1And Imax,2, electric current I sections of both sides protection seting value is respectively IsetI,1And IsetI,2, then
The out-of-limit probability of each Alloy White Iron is respectively：
P1=P (I'1≥Imax,1)=1-F1(Imax,1)
P2=P (I'2≥Imax,2)=1-F2(Imax,2)
P3=P (I1M≥IsetI,1)=1-F3(IsetI,1)
P4=P (I2M≥IsetI,2)=1-F4(IsetI,2)
According to the safety of the size qualitative assessment medium voltage distribution network Loop Closing Operation of the out-of-limit probability of each Alloy White Iron：If out-of-limit general
Rate is respectively less than 5%, then assert that the safety of Loop Closing Operation is higher, otherwise assert that the safety of this Loop Closing Operation cannot be protected
Card.
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| CN109787228A (en) * | 2019-02-14 | 2019-05-21 | 国网江西省电力有限公司电力科学研究院 | A kind of closed loop network condition judging method of data-driven |
| CN110071499A (en) * | 2019-04-03 | 2019-07-30 | 国网山东省电力公司济宁供电公司 | A kind of method and system of the quick safe cyclization of judgement power distribution network |
| WO2019233437A1 (en) * | 2018-06-05 | 2019-12-12 | 国网上海市电力公司 | Method for evaluating security of closed-loop operation of medium-voltage distribution network |
| CN110880765A (en) * | 2019-12-19 | 2020-03-13 | 深圳供电局有限公司 | Power distribution network closed loop operation method and system, closed loop operation equipment and storage medium |
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| WO2019233437A1 (en) * | 2018-06-05 | 2019-12-12 | 国网上海市电力公司 | Method for evaluating security of closed-loop operation of medium-voltage distribution network |
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| CN113379233A (en) * | 2021-06-08 | 2021-09-10 | 重庆大学 | Travel time reliability estimation method and device based on high-order moment |
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