CN109378834A - Large scale electric network voltage stability margin assessment system based on information maximal correlation - Google Patents

Large scale electric network voltage stability margin assessment system based on information maximal correlation Download PDF

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CN109378834A
CN109378834A CN201811296116.9A CN201811296116A CN109378834A CN 109378834 A CN109378834 A CN 109378834A CN 201811296116 A CN201811296116 A CN 201811296116A CN 109378834 A CN109378834 A CN 109378834A
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feature
voltage stability
formula
correlation
data
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李欣
郑之艺
李婉卿
邵凯旋
郭攀锋
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China Three Gorges University CTGU
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China Three Gorges University CTGU
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24Arrangements for preventing or reducing oscillations of power in networks
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

Large scale electric network voltage stability margin assessment system based on information maximal correlation, the system are primarily based on PMU data or software emulation, and obtaining one being capable of the approximate electric system large data sets for characterizing current all operation characteristics of electric system;On this basis, by repeatedly using MRMR algorithm, construction and voltage stability margin correlation maximum and the smallest feature set of redundancy;The function expression of relationship between selected variable and VSM is constructed using MATLAB;The real-time variable data obtained by electric system, can pass through expression formula direct estimation VSM.And result is fed back into spot dispatch personnel, to make a policy in time.The present invention can solve the disadvantages of Traditional measurements method low precision, speed are slow, poor to loss of data poor robustness and assessment analyticity, meet the real-time evaluation requirement of large-scale electrical power system.

Description

Large scale electric network voltage stability margin assessment system based on information maximal correlation
Technical field
The present invention relates to large-scale electrical power systems to run control technology field, specifically a kind of based on information maximal correlation Large scale electric network voltage stability margin assessment system.
Background technique
Electric system is most complicated one of man-made system, and with China's expanding economy, the demand of network load is increasingly Increase.And it is corresponding, the transmittability of electric system is not obviously improved, transmission capacity still be limited, system Operating point is also increasingly closer to the limit of power system stability operation.Pass through the summary discovery to many large-scale blackouts, voltage Collapse the entire power system collapse during from important role.Therefore, the voltage stability of electric system is carried out real When monitoring, guarantee operation of power networks operating point have enough voltage stability margins, to the safe and reliable operation of entire electric system It is significant.
With the extensive interconnection of current electric grid, the stable appraisal procedure of electric system of the tradition based on model needs to carry out big The circuit approximately equivalent of scale, Evaluation accuracy is poor, while its estimating velocity is also difficult to meet the requirements.In recent years, with calculating The intelligent algorithms such as the fast development of machine technology, artificial neural network and decision tree are introduced into the stable assessment of electric system. Although there is these appraisal procedures faster estimating velocity also respectively to have deficiency in practical applications.Artificial neural network conduct A kind of "black box" algorithm can not know the specific incidence relation between input and output, it is difficult to stable control and electricity for power grid Failure backtracking after Force system unstability provides important information.Although decision tree class method analyticity is stronger, to loss of data Robustness is very poor, and the loss of core feature data may cause the failure of entire assessment models.
Therefore, the stable appraisal procedure of voltage suitable for extensive interconnected electric power system how is constructed, system variable is provided The Analytical Expression of " transparent " between the stable nargin of voltage improves the robustness problem to loss of data, final to realize to whole Accurate, the quick and stable assessment of a Network Voltage Stability nargin is when previous urgent problem to be solved.
Summary of the invention
In order to solve problem above, the invention proposes a kind of large scale electric network voltage stabilizations based on information maximal correlation Nargin assessment system, intend to solve Traditional measurements method low precision, speed it is slow, to loss of data poor robustness and assessment analyticity it is poor The disadvantages of, meet the real-time evaluation requirement of large-scale electrical power system.
The technical scheme adopted by the invention is as follows:
Large scale electric network voltage stability margin assessment system based on information maximal correlation, comprising: basic data extract with Memory module, static voltage stability characteristic extracting module, topological transformation module, online evaluation module;
The basic data is extracted and memory module, is used for based on scene/history PMU data, or using MATLAB and Python program controls power system simulation software PSS/E, acquires the Operation of Electric Systems data under different operating point, It is final to obtain the electric system large data sets for capableing of the approximate current all operation characteristics of electric system of characterization.Then for every One operating point calculates its corresponding voltage stability margin VSM;
The static voltage stability characteristic extracting module is used to extract and voltage stability margin correlation maximum and superfluous The feature set of remaining property minimum MRMR becomes for finding one group with target wherein containing the MRMR algorithm based on information redundancy The characteristic variable collection of correlation maximum is measured, and the correlation that feature is mutual in variables set is minimum.MRMR algorithm is repeatedly used, Multiple and different feature sets can then be obtained;
The topological transformation module is constructed between different variables and corresponding voltage stability margin by curve fitting technique Mathematical analysis relationship, for each topology, record its acquisition voltage stability margin function expression and corresponding parameter, such as Unknown change in topology is detected in fruit electric system, then according to newest current operating situation extract again characteristic variable collection and Mathematical analysis relationship is constructed, new model to be assessed is generated.
The online evaluation module is used for the new variables data obtained using electric system, steady by the voltage of acquisition Determine nargin expression formula and directly carry out the stable assessment of voltage, and result is fed back into spot dispatch personnel, to make a policy in time.
In the basic data extraction and memory module, using under MATLAB and Python programmed acquisition different operating point Operation of Electric Systems data include: the distribution function that system randomly selects load parameter first, meanwhile, utilize optimal load flow OPF Determine its dependent variable such as the distribution of reality/reactive power and position of tapping switch.Then, original generator/load distribution is generated. Different generators/load increases direction, and identical original generator/load distribution is made to generate different voltage stability boundaries Point.In order to record more electric system behaviors, increase knowledge base, the load growth rate of different zones is set as not by the present invention Together, and in the same area keep power factor constant.Meanwhile increment load mainly pass through the same area generator carry out it is flat Weighing apparatus.Increase direction the result is that increasing direction and being similar to actual load.Constantly to load/generated output power in system into Row increases, until system reaches quiescent voltage collapse point POC.It is collected and stored in during this corresponding to all system operating points System variable value.
The basic data is extracted with memory module, and voltage stability margin VSM calculation method is as follows:
Wherein: PPOCFor the maximum active power that current system can transmit, i.e. peak load at collapse point.POPTo work as System active power under first operating status.VSM can characterize current point of operation to the distance between collapse of voltage point.
In the static voltage stability characteristic extracting module, MRMR algorithm, core concept is correlation between finding feature The maximum value of difference between redundancy is realized especially by formula (2):
In formula: H (fi) and H (fj) be respectively ith feature and j-th of feature entropy, { f1, f2, f3…fFIt is wait mention The feature set taken, F are characterized the number of features of concentration, MI (fi, y) and indicate fi" similar " degree between feature and target class y, MI(fi, fj) indicate feature set internal feature between " similar " degree, specifically determined by following formula:
Wherein, fi,xFor fiX-th of element, yxFor x-th of element of target variable y, p (fI, x) and p (yx) respectively indicate fI, xAnd yxMarginal probability density function, p (fi,x,yx) indicate their joint probability distribution, p (fi,x,fi,y) indicate fi,x fi,yJoint probability distribution.
In the static voltage stability characteristic extracting module, the cumulative search routine of MRMR algorithm is as follows:
(a) first feature selecting.Association relationship between each candidate feature and target class is calculated by formula (3). Data set (D) is created for optional features, and selects the highest characteristic (f of MI valuei, y) and it is used as first optional features.
(b) second feature selecting.Association relationship between first selected feature and other candidate features is counted by formula (4) It obtains.Select MI (fi,fj) the smallest feature of value is as second selection feature.
(c) subsequent feature selecting.There are the data of the two selection features, correlation and redundancy point in data set D It can not be calculated by formula (3) and formula (4).Hereafter the information redundancy optimal algorithm as shown in (2) formula is constantly applied, is selected item by item Take subcharacter.If having reached the specified quantity of selected feature, algorithm is terminated.
The present invention provides a kind of large scale electric network voltage stability margin assessment system based on information maximal correlation, the system It is primarily based on PMU data or software emulation, obtaining one being capable of the approximate electric power for characterizing current all operation characteristics of electric system System large data sets;On this basis, by repeatedly using MRMR algorithm, construction and voltage stability margin correlation maximum and superfluous The remaining the smallest feature set of property;The function expression of relationship between selected variable and VSM is constructed using MATLAB;Pass through electric system The real-time variable data obtained, can pass through expression formula direct estimation VSM.And result is fed back into spot dispatch personnel, with Just it makes a policy in time.
Compared with conventional method, beneficial effect of the present invention are as follows: system uses the appraisal procedure based on information redundance, energy The comprehensive whole statistical probability considered between variable of enough systems, has better adaptability to extensive interconnected electric power system;System System is excavated and is extracted to stable feature using maximal correlation minimal redundancy criterion, and over-fitting and poor fitting can be effectively prevented The generation of phenomenon improves the precision of system evaluation;Based on the stability margin analytical expression that curve matching obtains, have good Analyticity, can for the failure after the stable control and electric system unstability of power grid recall important information be provided;While method is most The assessment models obtained eventually are convenient for storage and calculate, and have good estimating velocity.
Detailed description of the invention
Fig. 1 is system diagram of the invention;
Fig. 2 is the overview flow chart of the embodiment of the present invention;
Fig. 3 is the composition block diagram that basic data extracts with memory module in the present invention;
Fig. 4 is the composition block diagram of static voltage stability characteristic extracting module in the present invention;
Fig. 5 is the composition block diagram of topological transformation module in invention.
Specific embodiment
Large scale electric network voltage stability margin assessment system based on information maximal correlation, for large-scale power train System carries out Transient Stability Evaluation, assesses in voltage stability margin of the global level to power grid entirety, guarantees system more steady It is run in the state of fixed, reliable.The assessment system is extracted it is characterized by comprising basic data and memory module, quiescent voltage are steady Determine characteristic extracting module, four parts of topological transformation module and online evaluation module.
Basic data is extracted and memory module, is based on scene/history PMU data, or utilize MATLAB and Python program Power system simulation software PSS/E is controlled, the Operation of Electric Systems data under different operating point is acquired, finally obtains one A electric system large data sets for capableing of the approximate current all operation characteristics of electric system of characterization.Then for each work Point calculates its corresponding voltage stability margin VSM.
Using the Operation of Electric Systems data under MATLAB and Python programmed acquisition different operating point, detailed process is such as Under: system randomly selects the distribution function of load parameter first, meanwhile, reality/reactive power is determined using optimal load flow (OPF) Its dependent variable such as distribution and position of tapping switch.Then, original generator/load distribution is generated.Different generator/loads Increase direction, identical original generator/load distribution is made to generate different voltage stability boundary points.In order to record more electricity Force system behavior increases knowledge base, and the load growth rate of different zones is set as different by the present invention, and is kept in the same area Power factor is constant.Meanwhile increment load mainly passes through the generator of the same area and is balanced.The result is that it is similar to increase direction Increase direction in actual load.Constantly load/generated output power in system is increased, until system arrival is quiet State collapse of voltage point (POC).It is collected and stored in system variable value corresponding to all system operating points during this.
The calculating works of voltage stability margin are as follows:
Wherein PPOCFor the maximum active power that current system can transmit, i.e. peak load at collapse point.POPFor in the ban System active power under operating status.VSM can characterize current point of operation to " distance " between collapse of voltage point.
Static voltage stability characteristic extracting module: it extracts and voltage stability margin correlation maximum and redundancy minimum (MRMR) feature set.Wherein contain the MRMR algorithm based on information redundancy, it is intended to find one group it is related to target variable Property maximum characteristic variable collection, and the correlation that feature is mutual in variables set is minimum.Repeatedly use MRMR algorithm, then it can be with Obtain multiple and different feature sets.
MRMR algorithm, core concept are the maximum values of difference between correlation and redundancy between finding feature, specific logical Cross formula (2) realization:
H (f in formulai) and H (fj) be respectively ith feature and j-th of feature entropy, { f1, f2, f3…fFIt is to be extracted Feature set, F is characterized the number of features of concentration, MI (fi, y) and indicate fi" similar " degree between feature and target class y, MI (fi, fj) indicate feature set internal feature between " similar " degree, specifically determined by following formula:
Wherein, fi,xFor fiX-th of element, yxFor x-th of element of target variable y, p (fI, x) and p (yx) respectively indicate fI, xAnd yxMarginal probability density function, p (fi,x,yx) indicate their joint probability distribution, p (fi,x,fi,y) indicate fi,x fi,yJoint probability distribution.
MRMR algorithm is a kind of incremental search process, and referred to as " order algorithm ", specifically cumulative search routine is as follows:
(a) first feature selecting.Association relationship between each candidate feature and target class is calculated by formula (3). Data set (D) is created for optional features, and selects the highest characteristic (f of MI valuei, y) and it is used as first optional features.
(b) second feature selecting.Association relationship between first selected feature and other candidate features is counted by formula (4) It obtains.Select MI (fi,fj) the smallest feature of value is as second selection feature.
(c) subsequent feature selecting.There are the data of the two selection features, correlation and redundancy point in data set D It can not be calculated by formula (3) and formula (4).Hereafter the information redundancy optimal algorithm as shown in (2) formula is constantly applied, is selected item by item Take subcharacter.If having reached the specified quantity of selected feature, algorithm is terminated.
Topological transformation module: the mathematics between different variables and corresponding voltage stability margin is constructed by curve fitting technique Parsing relationship.
Topological transformation module: for each topology, the voltage stability margin function expression of its acquisition and corresponding is recorded Parameter.If detecting unknown change in topology in electric system, feature is extracted according to newest current operating situation again Variables set and building mathematical analysis relationship, generate new model to be assessed.
Online evaluation module: the new variables data obtained using electric system can pass through the voltage stability margin of acquisition Expression formula directly carries out the stable assessment of voltage, and result is fed back to spot dispatch personnel, to make a policy in time.
Embodiment:
General frame in embodiment is as shown in Figure 1, system is mainly extracted by basic data and memory module, quiescent voltage are steady Determine characteristic extracting module, topological transformation module and online evaluation module composition.Basic data is extracted and memory module, the purpose is to Large-scale history data set based on live PMU establishes the statistical model for being similar to all stochastic variable probability distribution;It is static Voltage stabilization characteristic extracting module constructs and voltage stability margin correlation maximum and the smallest feature set of redundancy;Topology In conversion module, by curve matching, the topological relation between different variables and corresponding VSM is constructed;Online evaluation module, passes through The new variables data that electric system obtains, can feed back to spot dispatch people by expression formula direct estimation VSM, and by result Member, to make a policy in time.
The overall execution flow chart of embodiment is as shown in Fig. 2, specifically include following steps:
(1) PSS/E emulator is controlled using MATLAB and Python program, automatic collection PSS/E data, is established The electric system large data sets of one record performance variable and corresponding VSM, and calculated corresponding to each operating point by formula (1) Voltage stability margin VSM.
(2) by MRMR algorithm, the relationship between performance variable and VSM is constructed, and record the table of heterogeneous networks topology Up to formula.
(3) when new service condition occurs, compare present topology and data concentrate existing topology, determine that the topology is It is no to be recorded.
(3 ') use corresponding feature set and expression formula if the topology is existing topological classification in data set.
(3 ") if the topology be new topology MRMR process is applied in new topology under new service condition, Obtain new expression formula.
(4) according to obtained relationship, voltage stability margin assessment is carried out to current operating point.
Fig. 3 is the composition block diagram that basic data extracts with memory module in the present invention.In the module, system is random first The distribution function of load parameter is chosen, meanwhile, the distribution of reality/reactive power and tap switch are determined using optimal load flow (OPF) Its dependent variable such as position.Then, original generator/load distribution is generated.Different generators/load increases direction, makes phase Same original generator/load distribution generates different voltage stability boundary points.In order to record more electric system behaviors, increase Add knowledge base, the load growth rate of different zones is set as different by the present invention, and keeps power factor constant.Meanwhile increment is negative The generator that lotus mainly passes through the same area is balanced.Increase direction the result is that increasing direction and being similar to actual load.No It is disconnected that load/generated output power in system is increased, until system reaches quiescent voltage collapse point.It collects and stores System variable value corresponding to all system operating points in the process.
Fig. 4 is the composition block diagram of static voltage stability characteristic extracting module in the present invention.Specific workflow are as follows:
(1) correlation calculations.Between correlation and feature and target class y by calculating data set D and target class y " similar " degree, finds out the feature with target variable correlation maximum.
(2) redundant computation.By calculating selected characteristic value redundancy that may be present, filter out with target variable redundancy most Small feature.
(3) MRMR algorithm.By MRMR algorithm, the feature of one group with target variable correlation maximum is found, and they it Between correlation it is minimum.
As a preferred solution of the present invention, relative parameters setting is as follows in the present embodiment:
(1) in PSS/E system, test and generate the operating point 8168 of a variety of different voltage margins, each work Contain 31838 variables in point.
(2) in 8168 samples of generation, wherein 6535 samples are trained for random selection, and 1633 samples give over to Test.
(3) then 10 MRMR feature sets (M=10) of parallel generation, include that 5 features become in each MRMR feature set It measures (N=5).
Fig. 5 is the composition block diagram of topological transformation module in the present invention.Specific workflow are as follows:
(1) by MRMR algorithm, the relationship between performance variable and VSM is constructed, and record the table of heterogeneous networks topology Up to formula.
(2) when new service condition occurs, compare present topology and data concentrate existing topology, determine that the topology is It is no to be recorded.
(3) if the topology is existing topology in data set, corresponding feature set and expression formula are used.
(4) if the topology is that MRMR algorithm is applied in new topology by new topology under new service condition, Obtain new expression formula.
As a preferred solution of the present invention, the characteristic variable type in first MRMR feature set finally obtained, And the mathematical function relationship between each characteristic variable and voltage stability margin is as shown in the table;
As a preferred solution of the present invention, in online evaluation module, due to that can have been generated during multiple MRMR The feature set of 10 different solutions, each selection can provide VSM estimated value, finally be capable of providing more acurrate result Aggregation decisions.
The statistical accuracy that the present invention is assessed in 1648 bus systems test result is as follows table:
The relevant measuring and calculation time is as shown in the table:
Dependence test the result shows that, if encountering new topological structure in 1648 bus-bar systems, the online updating stage can To provide accurate assessment result in 10 minutes.If the topology of electric system is recorded in known topology List, program Assessment result can be provided in 0.67 second.It is fully able to meet the requirement of online evaluation.
The final testing result of embodiment shows more effectively, more completely indicate target category information with MRMR method. Meanwhile compared with other transparent AIS tools, MRMR method has higher assessment accuracy rate.It is unseen before encountering to open up When flutterring variation, MRMR technology can be used the example newly obtained and refresh selected variable and corresponding function expression.The side MRMR Method has quick training and predetermined speed, can satisfy the requirement that real-time online uses.In practical applications, it is recommended to use sample It is equal to or more than the variable quantity of the determining parameter of experiment in this amount, the quantity and each feature set of parallel MRMR process.

Claims (10)

1. the large scale electric network voltage stability margin assessment system based on information maximal correlation, characterized by comprising: basic number According to extraction and memory module, static voltage stability characteristic extracting module, topological transformation module, online evaluation module;
The basic data is extracted and memory module, is used for based on scene/history PMU data, or using MATLAB and Python program controls power system simulation software PSS/E, acquires the Operation of Electric Systems data under different operating point, It is final to obtain the electric system large data sets for capableing of the approximate current all operation characteristics of electric system of characterization;Then for every One operating point calculates its corresponding voltage stability margin VSM;
The static voltage stability characteristic extracting module is used to extract and voltage stability margin correlation maximum and redundancy The feature set of minimum MRMR, wherein the MRMR algorithm based on information redundancy is contained, for finding one group and target variable phase The maximum characteristic variable collection of closing property, and the correlation that feature is mutual in variables set is minimum;MRMR algorithm is repeatedly used, then can Access multiple and different feature sets;
The topological transformation module constructs the mathematical analysis relationship between different variables and corresponding voltage stability margin, for every A topology records voltage stability margin function expression and corresponding parameter that it is obtained, if detected not in electric system The change in topology known then extracts characteristic variable collection and building mathematical analysis relationship according to newest current operating situation again, raw The model to be assessed of Cheng Xin;
The online evaluation module is used for the new variables data obtained using electric system, abundant by the voltage stabilization of acquisition Degree expression formula directly carries out the stable assessment of voltage, and result is fed back to spot dispatch personnel.
2. the large scale electric network voltage stability margin assessment system based on information maximal correlation according to claim 1, special Sign is: in the basic data extraction and memory module, using under MATLAB and Python programmed acquisition different operating point Operation of Electric Systems data include: the distribution function that system randomly selects load parameter first, meanwhile, utilize optimal load flow OPF Determine its dependent variable such as the distribution of reality/reactive power and position of tapping switch;Then, original generator/load distribution is generated; Different generators/load increases direction, and identical original generator/load distribution is made to generate different voltage stability boundaries Point;The load growth rate of different zones is set as different by the system, and keeps power factor constant in the same area;Meanwhile The generator that increment load mainly passes through the same area is balanced;The result is that increasing direction is similar to actual load increase side To;Constantly load/generated output power in system is increased, until system reaches quiescent voltage collapse point POC;It receives Collect and stores system variable value corresponding to all system operating points in the process.
3. the large scale electric network voltage stability margin assessment system based on information maximal correlation according to claim 1, special Sign is: the basic data is extracted with memory module, and voltage stability margin VSM calculation method is as follows:
Wherein: PPOCFor the maximum active power that current system can transmit, i.e. peak load at collapse point;POPTo transport in the ban System active power under row state;VSM can characterize current point of operation to the distance between collapse of voltage point.
4. the large scale electric network voltage stability margin assessment system based on information maximal correlation according to claim 1, special Sign is: in the static voltage stability characteristic extracting module, MRMR algorithm, core concept be between finding feature correlation with The maximum value of difference between redundancy is realized especially by formula (2):
In formula: H (fi) and H (fj) be respectively ith feature and j-th of feature entropy, { f1, f2, f3…fFIt is to be extracted Feature set, F are characterized the number of features of concentration, MI (fi, y) and indicate fi" similar " degree between feature and target class y, MI (fi, fj) indicate feature set internal feature between " similar " degree, specifically determined by following formula:
Wherein, fi,xFor fiX-th of element, yxFor x-th of element of target variable y, p (fI, x) and p (yx) respectively indicate fI, x And yxMarginal probability density function, p (fi,x,yx) indicate their joint probability distribution, p (fi,x,fi,y) indicate fi,x fi,y's Joint probability distribution.
5. the large scale electric network voltage stability margin assessment system based on information maximal correlation according to claim 1, special Sign is: in the static voltage stability characteristic extracting module, the cumulative search routine of MRMR algorithm is as follows:
(a) first feature selecting;Association relationship between each candidate feature and target class is calculated by formula (3);For choosing Fixed characteristic creates data set (D), and selects the highest characteristic (f of MI valuei, y) and it is used as first optional features;
(b) second feature selecting;Association relationship between first selected feature and other candidate features is calculated by formula (4) It arrives;Select MI (fi,fj) the smallest feature of value is as second selection feature;
(c) subsequent feature selecting;There are the data of the two selection features, the correlation and redundancy in data set D respectively can It is calculated by formula (3) and formula (4);Hereafter the information redundancy optimal algorithm as shown in (2) formula is constantly applied, chooses son item by item Feature;If having reached the specified quantity of selected feature, algorithm is terminated.
6. the large scale electric network voltage stability margin appraisal procedure based on information maximal correlation, it is characterised in that including following step It is rapid:
(1), it is based on scene/history PMU data, or using MATLAB and Python program to power system simulation software PSS/E It is controlled, acquires the Operation of Electric Systems data under different operating point, final acquisition one approximate can characterize current electric power The electric system large data sets of all operation characteristics of system;Then it is directed to each operating point, calculates its corresponding voltage stabilization Nargin VSM;
(2), by repeatedly using MRMR algorithm, in electric system large data sets, M different feature sets, Mei Gete are extracted Sign be concentrated with N number of variable, the voltage stability margin correlation maximum of these variables and system, and the feature in same feature set it Between correlation it is minimum;Specific MRMR specific algorithm includes correlation calculations, and redundancy calculates and MRMR calculates three parts;
(3), the function expression of relationship between selected variable and VSM is constructed using the curve fitting module in MATLAB;
(4), when detecting that system topological changes, then will occur new parsing relationship, i.e., existing table between variable and VSM It is no longer applicable in up to formula;It needs to apply to MRMR process in new topology under new service condition at this time, obtains variable and VSM New relationship, realize online data update;
(5), the new variables data obtained by electric system, can pass through expression formula direct estimation VSM;And result is fed back to Spot dispatch personnel, to make a policy in time.
7. the large scale electric network voltage stability margin appraisal procedure based on information maximal correlation according to claim 6, special Sign is: most relevance minimal redundancy (MRMR) algorithm in the step (2), target is looked on the basis of mutual information To one group of relevant complementary characteristic;The basis of this technology is, if having close connection between two features, they are dividing Similar effect is played in class or prediction;Both therefore, there is no need to will be included in optional features concentrates, and whether they are from no It is highly relevant with target object class;MRMR algorithm includes that relevance calculating and redundancy calculate two parts;Specifically, electric system Data set D is expressed as S sample and F={ f1, f2, f3…fFFeature (operating parameter);Y is target variable VSM;MRMR algorithm Target is to find subspace M={ m1, m2, m3….mM, RM;From F and RFTarget y class can be complementally portrayed comprehensively.
8. the large scale electric network voltage stability margin appraisal procedure based on information maximal correlation according to claim 6, special Sign is: the method for the correlation calculations in the step (2) is as follows:
The correlation (being denoted as U (D, y)) of data set D and target class y is by all mutual informations between each feature and target class y (MI) average value of value is measured, as follows:
Wherein F is characterized the size of collection;MI(fi, y) and indicate " similar " degree between feature and target class y, it is defined as follows;
Wherein, fi,xFor fiX-th of element, yxFor x-th of element of target variable y, p (fI, x) and p (yx) respectively indicate fI, x And yxMarginal probability density function, p (fi,x,yx) indicate their joint probability distribution;
The method that redundancy in the step (2) calculates is as follows:
It there may be redundancy between the feature chosen according to formula (2);V (F) indicates similar (redundancy) journey between different characteristic Degree, can be calculated by formula (4):
Wherein fi, fjRespectively indicate ith and jth feature, MI (fi,fj) calculated by formula (5), indicate their mutual information;
Wherein, p (fi,x,fi,y) indicate fi,x fi,yJoint probability distribution;
The method that final MRMR in the step (2) is calculated is as follows:
The target of maximal correlation minimal redundancy algorithm is the feature (VSM) for finding one group with target variable correlation maximum, and root According to expression above (2) and (4), the correlation between them is minimum;In practice, most relevance U (D, y) and minimal redundancy V (F) cannot be realized always simultaneously;It is optimized, is combined into a standard, provided by expression formula (6);Wherein, H (fi) and H (fj) be respectively ith feature and j-th of feature entropy;
9. the large scale electric network voltage stability margin appraisal procedure based on information maximal correlation according to claim 6, special Sign is: the MRMR algorithm in the step (2) is a kind of incremental search process, referred to as " order algorithm ", is added up and following institute Show:
A) first feature selecting;Association relationship between each candidate feature and target class is calculated by formula (3);It is selected Characteristic create data set (D), and select the highest characteristic (f of MI valuei, y) and it is used as first optional features;
B) second feature selecting;Association relationship between first selected feature and other candidate features is calculated by formula (5) It arrives;Select MI (fi,fj) the smallest feature of value is as second selection feature;
C) subsequent feature selecting;There are the data of the two selection features, the correlation and redundancy in data set D are respectively by formula (2) it is calculated with formula (4);Maximal correlation minimal redundancy criterion is realized, expression formula is formula (6);It should by reusing Criterion chooses subcharacter item by item;If having reached the specified quantity of selected feature, algorithm is terminated.
10. the large scale electric network voltage stability margin appraisal procedure based on information maximal correlation according to claim 6, special Sign is: in the step (5), final evaluation result R is calculated using formula (7)F
M is the sum of selected characteristic set, and N is the variable number in each characteristic set, RijIt is j-th in ith feature set The corresponding estimated result of characteristic variable.
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