CN105740989B - A kind of water supply network anomalous event method for detecting based on VARX model - Google Patents

A kind of water supply network anomalous event method for detecting based on VARX model Download PDF

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CN105740989B
CN105740989B CN201610078560.8A CN201610078560A CN105740989B CN 105740989 B CN105740989 B CN 105740989B CN 201610078560 A CN201610078560 A CN 201610078560A CN 105740989 B CN105740989 B CN 105740989B
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徐哲
熊晓锋
洪嘉鸣
何必仕
陈云
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Hangzhou Dianzi University
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Abstract

The invention discloses a kind of water supply network anomalous event method for detecting based on VARX model.The present invention carries out measuring point grouping first, determines input sample.Secondly VARX model is established by grouping.Then it carries out pressure prediction and calculates difference, and calculate the average and standard deviation of difference.Finally anomalous event is detected according to anomalous event decision rule.The present invention is based on the water supply network anomalous event method for detecting that VARX model uses variance analysis, have the features such as strong interference immunity, detecting ability is strong.

Description

A kind of water supply network anomalous event method for detecting based on VARX model
Technical field
The invention belongs to urban water supply field, specifically a kind of water supply network anomalous event detecting side based on VARX model Method.
Background technique
Dark leakage and booster are two kinds of common anomalous events of public supply mains, the former have the time persistently length, small scale, Not noticeable feature, and the latter is then exactly the opposite, has sudden, uncertain, sweeping feature.Discovery is supplied water in time Leakage loss event present in pipe network is accurately positioned venue location point, takes measures to prevent the state of affairs from deteriorating rapidly, to water supply network It is particularly important for safe operation.
Water supply network anomalous event detecting at present is based primarily upon microcosmic hydraulic model and two kinds of macro-data model.Wherein Micromodel needs the particulars of known pipe network system, such as the topological structure of pipe network, the material of pipeline section, length, diameter, frictional resistance Equal specifying informations, the domestic application study based on micromodel are less.Research based on macromodel is broadly divided into marginal analysis With two methods of variance analysis, marginal analysis method vulnerable to noise interference and difference analysis method anti-interference ability is stronger.
In view of this, can preferably be detected to water supply network anomalous event using difference analysis method.The present invention Discriminant analysis, which is carried out, based on VARX model high-precision forecast detects water supply network anomalous event.
Summary of the invention
The water supply network anomalous event detecting based on VARX model that in view of the deficiencies of the prior art, the present invention provides a kind of Method.Wherein VARX (a Vector Auto-Regressive with eXogenous variables) model by it is unidirectional because The variable of fruit relationship is added in VAR model as exogenous variable, can effectively enhance the disturbance rejection of model, while the model Precision with higher.
In order to achieve the above object, the present invention takes following steps:
The grouping of step 1. measuring point, determines input sample
Establish water supply network forecast database.Wherein input data includes: measurement point pressure, flow value etc.;Output data It include: forecast pressure, flow value etc..
(1) monitoring point is grouped
Monitoring point is grouped by correlation, correlation calculations formula is as follows:
Illustrate: x, y are two groups of time series datas;Ex, Ey are the desired values of corresponding two groups of time series datas;Dx, Dy is the variance of corresponding two groups of time serieses;Corr (x, y) is then the related coefficient of corresponding two groups of time series datas, is used To characterize correlation.The value range of related coefficient indicates uncorrelated 0~1,0, otherwise 1 indicates that correlation is obvious, will be related The apparent monitoring point of property is classified as one kind.
(2) input sample is determined
It is grouped according to monitoring point and determines that input sample is { xt,yt}i, wherein xtExogenous variable, y are tieed up for dtTo change in k dimension Amount, i.e., the monitoring point of the endogenous variable of monitoring point k of d exogenous variable, t are chronomere, and i indicates i-th group of monitoring point.
Step 2. establishes VARX model by grouping
VARX model is established in prediction each time for each group of monitoring point, according to input sample data { xt,yt}iCarry out mould Type determines rank and establishes model.
(1) VARX model order
Using AIC (Akaike Information Criterion) order selection criteria.It is defined as follows:
WhereinFor residual error, T is sample cycle, and p is that model lags item, and p value when AIC value is minimized is that model is best Selective value.
(2) VARX model is established
The expression formula of VARX model are as follows:
Wherein: xtExogenous variable is tieed up for d;ΘjCoefficient matrix to be estimated is tieed up for k × d.ytFor the endogenous variable of k dimension;C is The constant term of k dimension;ΦiCoefficient matrix to be estimated is tieed up for k × k;P1, q1 are lag order;{εtIt is that k ties up white noise sequence.
The parameter Estimation of VARX model is obtained using maximum-likelihood method, setting: β=vec ([c Φ1...Φp1Θ1... Θq1]),Then above formula may be expressed as:
yt=Wt-1β+εt
Then had according to maximum likelihood algorithm:
From β andAspect we can to derive model parameter as follows:
Step 3. pressure prediction simultaneously calculates difference
The predicted value of each monitoring point is obtained according to sample data and established model, and is calculated every in monitoring point n days The difference of one moment predicted value and observation.Wherein VARX model predication value is (Y '1j,Y′2j,...,Y′ij), observation is (x1j,x2j,...,xij), i=1...k (k indicates monitoring point pressure data number), j=1...n, then difference may be expressed as:
Δyij=(x1j-Y′1j,x2j-Y′2j,...,xij-Y′ij)
The average and standard deviation of step 4. calculating difference
Calculate the average and standard deviation of each monitoring point difference in M days.The sample frequency of assumed stress time series It is u min/ times, M days difference can be indicated such as step 3, then the average value of one day differenceIt can be by following Formula be calculated, wherein q=1...u...1440/u.
Standard deviation (σ12,...,σq) can be calculate by the following formula to obtain:
Step 5. detects anomalous event
According to following anomalous event decision rules, the abnormal conditions of detecting real-time water supply network:
A. any time point pressure, Flow Observation value are lower than -4 boundaries σ;
B. continuous 2 time point pressures, Flow Observation value are lower than -3 boundaries σ;
C. continuous 4 time point pressures, Flow Observation value are lower than -2 boundaries σ;
D. continuous 8 time point pressures, Flow Observation value are lower than -1 boundary σ.
Once observation touches decision rule, then assert that pipe network anomalous event occurs, the moment occurs for record, and triggers corresponding Early warning.
Beneficial effects of the present invention: the present invention is based on VARX models using the water supply network anomalous event detecting of variance analysis Method has the features such as strong interference immunity, detecting ability is strong.
Detailed description of the invention
Fig. 1: DMA 10, area monitoring point distribution map;
Specific embodiment
To make the technological means realized of the present invention be easy to express with creation characteristic, with reference to the accompanying drawing and example, to this hair Bright real-time mode is described in further detail.
Certain area DMA (District Metering Area) is considered in this example, there are 10 effective pressure measuring points, it is geographical Position such as Fig. 1.Three water inlet pressure spots (respectively with P1, P2, P3 expression) are introduced simultaneously and the area DMA water consumption is used as and changes outside Amount.Pressure data time range is from X March 20 to X April 3, wherein establishing mould using March 20 to data on April 2 Type detects April 3 " 5 simulation booster tests " anomalous event.Here, it is only illustrated with pressure value, but this Inventive method is equally applicable to flow value.
Step 1. determines input data
Establish water supply network forecast database.Wherein input data includes: measurement point pressure value, flow value etc.;Export number According to including: forecast pressure value etc..
(1) monitoring point is grouped
Pressure monitoring point and water inlet pressure spot are grouped by correlation, correlation calculations formula is as follows:
Illustrate: x, y are two groups of time series datas;Ex, Ey are the desired values of corresponding two groups of time series datas;Dx, Dy is the variance of corresponding two groups of time serieses;Corr (x, y) is then the related coefficient of corresponding two groups of time series datas.? Table 1 is grouped as follows to pressure monitoring point.
Table 1: monitoring point is grouped situation table
Group number Monitoring point member
First group No.3、No.5、No.6、No.7、No.10、P2
Second group No.1、No.8、No.9、P3
Third group No.2、No.4、P1
(2) input sample is determined
It is grouped according to monitoring point and determines that input sample is { xt,yt}i, wherein xtExogenous variable, y are tieed up for dtTo change in k dimension Amount, t are chronomere, and i indicates i-th group of monitoring point.The input sample of first group of monitoring point is 2 dimension exogenous variables, including P2 enters The endogenous variable of mouth of a river pressure-measuring-point and the area DMA water consumption, 5 dimensions is 5 pressure monitoring points, can similarly obtain remaining two groups of input Sample situation, sample frequency are 5min/ times.
Step 2. establishes VARX model
Model order and model are determined according to input sample, and the number of one day pressure monitoring point is predicted using five days data According to so needing to establish 3 × 10 models, i.e. three groups of monitoring points do not need to establish the VARX pressure of prediction 10 days on the 3.25th~4.3 Power prediction model.
(1) VARX model order
Using AIC (Akaike Information Criterion) order selection criteria.It is defined as follows:
WhereinFor residual error, T is sample cycle, and p is that model lags item, and p value when AIC value is minimized is that model is best Selective value.It is p=4 that model order, which is calculated,.
(2) VARX model is established
The expression formula of VARX model are as follows:
Wherein: xtExogenous variable is tieed up for d;ΘjCoefficient matrix to be estimated is tieed up for k × d.ytFor the endogenous variable of k dimension;C is The constant term of k dimension;ΦiCoefficient matrix to be estimated is tieed up for k × k;P1, q1 are lag order;{εtIt is that k ties up white noise sequence.
The parameter Estimation of VARX model is obtained using maximum-likelihood method, setting: β=vec ([c Φ1...Φp1Θ1... Θq1]),Then above formula may be expressed as:
yt=Wt-1β+εt
Then had according to maximum likelihood algorithm:
From β andAspect we can to derive model parameter as follows:
Step 3. pressure prediction simultaneously calculates difference
The predicted value of each monitoring point is obtained according to sample data and established model, and is calculated every in monitoring point n days The difference of one moment predicted value and observation.Obtain prediction data VARX model predication value (Y '1j,Y′2j,...,Y′ij), observation Value is (x1j,x2j,...,xij), wherein (k indicates monitoring point pressure data number, first group of k=5, second group of k=to i=1...k 3, third group k=2), j=1:10, then difference may be expressed as:
Δyij=(x1j-Y′1j,x2j-Y′2j,...,xij-Y′ij)
The average and standard deviation of step 4. calculating difference
Calculate the average and standard deviation of each monitoring point each sampled point in 9 days.Sample frequency is 5min/ times, then 9 It pressure data is represented by (x1j,x2j,...,xij), wherein i=1:k (first group of k=5, second group of k=3, third group k =2), j=1:9, then the average value of one day differenceIt can be calculated by following formula, wherein q= 1...5...288, M=9.
Standard deviation (σ12,...,σq) can be calculate by the following formula to obtain:
Step 5. abnormity detecting
To the pressure observed value of 10 monitoring points on April 3, according to following anomalous event decision rules:
A. any time point pressure observation is lower than -4 boundaries σ;
B. continuous 2 time points pressure observation value is lower than -3 boundaries σ;
C. continuous 4 time points pressure observation value is lower than -2 boundaries σ;
D. continuous 8 time points pressure observation value is lower than -1 boundary σ.
For this sentences No. 2 monitoring points, the anomalous event detected such as table 2,5 simulation booster test situations of coincideing.
The anomalous event that table 2:2 is detected monitoring point
Serial number Abnormal time section Duration (min) Worst error (σ)
1 9:25 <5 -5.946
2 9:40 <5 -4.242
3 10:05 <5 -5.339
4 12:25 <5 -9.326
5 19:50 <5 -4.493

Claims (1)

1. a kind of water supply network anomalous event method for detecting based on VARX model, it is characterised in that this method includes following step It is rapid:
The grouping of step 1. measuring point, determines input sample, specifically:
Establish water supply network forecast database;Wherein input data includes: measurement point pressure, flow value;Output data includes: pre- Measuring pressure, flow value;
(1) monitoring point is grouped
Monitoring point is grouped by correlation, correlation calculations formula is as follows:
Wherein x, y are two groups of time series datas;Ex, Ey are the desired values of corresponding two groups of time series datas;Dx, Dy are pair The variance for the two groups of time serieses answered;Corr (x, y) is then the related coefficient of corresponding two groups of time series datas, for characterizing Correlation;The value range of related coefficient indicates uncorrelated 0~1,0, otherwise 1 indicates that correlation is obvious;
(2) input sample is determined
It is grouped according to monitoring point and determines that input sample is { xt,yt}i, wherein xtExogenous variable, y are tieed up for dtEndogenous variable is tieed up for k, i.e., The monitoring point of the endogenous variable of monitoring point k of d exogenous variable, t are chronomere, and i indicates i-th group of monitoring point;
Step 2. establishes VARX model by grouping
VARX model is established in prediction each time for each group of monitoring point, according to input sample data { xt,yt}iIt is fixed to carry out model Rank simultaneously establishes model;
(1) VARX model order
Using AIC order selection criteria;It is defined as follows:
WhereinFor residual error, T is sample cycle, and p is that model lags item, and p value when AIC value is minimized is model optimal selection Value;
(2) VARX model is established
The expression formula of VARX model are as follows:
Wherein: xtExogenous variable is tieed up for d;ΘjCoefficient matrix to be estimated is tieed up for k × d;ytFor the endogenous variable of k dimension;C is k dimension Constant term;ΦiCoefficient matrix to be estimated is tieed up for k × k;P1, q1 are lag order;{εtIt is that k ties up white noise sequence;
The parameter Estimation of VARX model is obtained using maximum-likelihood method, setting: β=vec ([c Φ1...Φp1 Θ1... Θq1]),Then above formula may be expressed as:
yt=Wt-1β+εt
Then had according to maximum likelihood algorithm:
From β andIt is as follows that aspect can derive model parameter:
Step 3. pressure prediction simultaneously calculates difference
The predicted value of each monitoring point is obtained according to sample data and established model, and calculates per a period of time in monitoring point n days Carve the difference of predicted value and observation;Wherein VARX model predication value is (Y1'j,Y2'j,...,Yij'), observation is (x1j, x2j,...,xij), i=1...k, j=1...n, k indicate monitoring point pressure data number, then difference may be expressed as:
Δyij=(x1j-Y′1j,x2j-Y′2j,...,xij-Y′ij)
The average and standard deviation of step 4. calculating difference
Calculate the average and standard deviation of each monitoring point difference in M days;The sample frequency of assumed stress time series is u Min/ times, M days difference can be indicated such as step 3, then the average value of one day differenceIt can be by following public affairs Formula is calculated, wherein q=1...u...1440/u;
Standard deviation (σ12,...,σq) can be calculate by the following formula to obtain:
Step 5. detects anomalous event
According to following anomalous event decision rules, the abnormal conditions of detecting real-time water supply network:
A. any time point pressure, Flow Observation value are lower than -4 boundaries σ;
B. continuous 2 time point pressures, Flow Observation value are lower than -3 boundaries σ;
C. continuous 4 time point pressures, Flow Observation value are lower than -2 boundaries σ;
D. continuous 8 time point pressures, Flow Observation value are lower than -1 boundary σ;
Once observation touches decision rule, then assert that pipe network anomalous event occurs, the moment occurs for record, and triggers corresponding pre- It is alert.
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CN106872657B (en) * 2017-01-05 2018-12-14 河海大学 A kind of multivariable water quality parameter time series data accident detection method
CN109344708B (en) * 2018-08-29 2021-10-22 昆明理工大学 Water supply pipe network pipe burst signal abnormity analysis method
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