CN110929391B - Method and system for calculating fault rate of power distribution network under typhoon disaster - Google Patents
Method and system for calculating fault rate of power distribution network under typhoon disaster Download PDFInfo
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Abstract
The invention provides a method and a system for calculating the fault rate of a power distribution network under typhoon disasters, wherein the method comprises the following steps: respectively establishing a probability density function model representing typhoon intensity and a probability distribution function model representing typhoon duration; establishing a power distribution network fault rate calculation model under typhoon disasters; and calculating the total probability of load power loss in the duration time of the typhoon disaster based on the power distribution network fault rate calculation model. The invention simultaneously considers the uncertainty of typhoon intensity and duration, analyzes the physical principle of different types of faults of the power distribution network caused by typhoon disasters and has higher accuracy. The method is used for modeling the fault rate of the power distribution network, the influence of typhoon intensity and duration on the fault rate of the power distribution network is comprehensively considered, the running state of the power distribution network under the typhoon disaster is completely and accurately described by carrying out detailed modeling on multiple disaster-causing factors and disaster-causing mechanisms of the typhoon disaster, and the precision of the fault rate model of the power distribution network is greatly improved by utilizing the advantage of combined driving of the data model.
Description
Technical Field
The invention belongs to the technical field of power grid configuration, and particularly relates to a method and a system for calculating the fault rate of a power distribution network under a typhoon disaster.
Background
The prediction of the fault rate of the power distribution network under the extreme event is an important means for improving the capability of the power distribution network to cope with extreme meteorological disasters, and the commonly used methods comprise a fault rate modeling method based on historical data, a fault rate modeling method based on a disaster-causing mechanism and a fault rate modeling method based on data model fusion.
The fault rate modeling method based on historical data mainly obtains the joint probability distribution of the fault rate of the multi-dimensional random variables by analyzing the correlation relation among the multi-dimensional random variables and analyzing the historical data and forecast data by using methods such as regression analysis, a fuzzy expert system, a maximum Expectation (EM) and the like. The method is driven by data, is not limited by a disaster mechanism and a disaster dynamic process, is completely separated from a physical model, and greatly reduces the modeling difficulty of the fault rate. However, due to the lack of modeling of a disaster-causing mechanism and a disaster dynamic process, the method is difficult to reflect the causal relationship between the development and change process of the disaster and the fault of the power distribution network equipment, and the prediction accuracy of the method is generally low due to the low occurrence probability of extreme events and the small amount of historical data.
The fault rate modeling method based on the disaster-causing mechanism mainly analyzes the disaster-causing mechanism and the dynamic disaster process, and utilizes a physical model to describe the influence of the disaster on the power distribution network, so as to establish a mechanism model and a dynamic change model of the fault rate of the power distribution network. Taking a fault model of typhoon as an example, relevant researches are carried out by analyzing wind speed, wind direction and geographical position data of typhoon in the past times, and using an outage prediction model to simulate the influence of future typhoon passing through, so as to predict the outage range and outage probability of a line. However, due to the fact that a disaster mechanism model is complex and the difference of disaster mechanisms of different disasters is large, the modeling difficulty of the method is large and the method is lack of generality; due to geographical and physical causal relationships in a catastrophe process, the failure rate of the power distribution network equipment in an extreme event is difficult to accurately reflect by adopting a static model.
Disclosure of Invention
In order to overcome the existing problems or at least partially solve the problems, embodiments of the present invention provide a method and a system for calculating a failure rate of a power distribution network in a typhoon disaster.
The embodiment of the invention provides a method for calculating the fault rate of a power distribution network under a typhoon disaster, which comprises the following steps:
establishing a probability density function model representing typhoon intensity based on historical data of typhoon wind speed and rainfall intensity under typhoon disasters;
establishing a probability distribution function model of typhoon duration;
establishing a power distribution network fault rate calculation model under the typhoon disaster based on the probability density function model representing the typhoon intensity and the probability distribution function model representing the typhoon duration;
and calculating the total probability of load power loss within the duration time of the typhoon disaster based on the power distribution network fault rate calculation model.
On the basis of the technical scheme, the invention can be improved as follows.
The establishing of the probability density function model representing the typhoon intensity based on the historical data of the typhoon wind speed and the rainfall intensity under the typhoon disaster comprises the following steps:
the time-varying probability vector v (t) for typhoon wind speed and rainfall intensity is expressed as:
V(t)＝[Vwind(t) Vrain(t)]；
in the formula: vwind(t) is the probability vector of typhoon wind speed at time t, Vrain(t) is a probability vector of rainfall intensity at time t;
and fitting historical data of typhoon wind speed and rainfall intensity to obtain a probability density function rho (V (t)) of V (t).
Further, the establishing a probability distribution function model of the typhoon duration includes:
and establishing a probability distribution function model of the typhoon duration by judging whether the typhoon intensity is reduced to the lowest grade standard at the moment t.
Further, the establishing of the probability distribution function model of the typhoon duration by judging whether the typhoon intensity is reduced to the lowest level standard at the time t includes:
typhoon duration T is expressed as:
T＝tend-tbegin；
in the formula: t is tbeginAt the beginning of a typhoon, tendBoundary value of beta confidence interval at typhoon end time
Obtained by the following formula:
in the formula:
the upper limit of the conditional confidence interval of the typhoon wind speed and the rainfall intensity, VwminIs the lowest level standard of typhoon wind speed, VrminThe standard is the lowest grade standard of rainfall intensity;
in the formula:
respectively is the lower limit of the condition confidence interval of the typhoon wind speed and the rainfall intensity;
the beta confidence interval for typhoon duration T is
Further, the establishing a power distribution network fault rate calculation model under the typhoon disaster based on the probability density function model representing the typhoon intensity and the probability distribution function model representing the typhoon duration comprises:
respectively establishing an electric pole fault rate model, an overhead line fault rate model, an insulator fault rate model and a transformer fault rate model;
and obtaining a power distribution network fault rate calculation model according to the electric pole fault rate model, the overhead line fault rate model, the insulator fault rate model and the transformer fault rate model.
Further, the establishing of the pole fault rate model includes:
establishing a function taking the state of the electric pole as a basic variable:
Z1＝R1-S1；
in the formula: r1 is the bending strength of the electric pole, S1 is the internal stress of the electric pole caused by wind load, and is related to wind speed and wind direction;
wherein, R1 is the Gauss distribution that electric pole bending strength obeys following formula:
in the formula: mu.sPIs the mean value of the bending strength of the concrete pole, deltaPIs the standard deviation of the bending strength of the concrete pole, beta and upsilon can be measured through actual operation experience or destructive test, MuChecking the bending moment for the bearing capacity of the concrete pole;
the normal operation probability of the electric pole at the moment t is as follows:
the failure rate of the pole at time t is
Further, the establishing an overhead line fault rate model includes:
calculating the self-weight L of the overhead lineGAnd maximum bearing stress LDesm：
In the formula: l isvFor vertical span of overhead lines, G0Mass per unit length of overhead wire, TmThe tension is determined by the type of the overhead line, and K is a safety coefficient;
the function with the overhead line state as the basic variable is as follows:
Z2＝R2-S2；
R2＝LG+LDesm；
in the formula: r2 is the tensile strength of the overhead line, S2 is the internal stress of the overhead line caused by wind load, and is related to wind speed and wind direction;
the failure rate of the overhead line at the time t is as follows:
in the formula: mu.sPIs the mean value of the tensile strength of the overhead wire, deltaPIs the standard deviation of the overhead wire tensile strength.
Further, the establishing of the insulator fault rate model comprises:
rainfall critical value A of insulator flashoverζExpressed as:
in the formula: u shapeζThe critical value of the flashover voltage of the insulator is obtained; p is the current ambient air pressure; p0The standard atmospheric pressure is adopted, and a, b and c are constants;
the flashover probability of a single insulator is:
in the formula: f (V)rain(t)) is a probability distribution function of rainfall intensity, and is obtained by the following formula:
further, the transformer fault rate model includes:
rainfall critical value A of spark discharge of transformer insulating oilζ1And the rainfall critical value A of the punctured oil-impregnated paperζ2Respectively expressed as:
in the formula: w1Moisture content of insulating oil for transformer，W2The moisture content of the transformer oil-immersed paper is measured, and N is the rainfall duration, namely the duration t of the typhoon disastertotal，a1、a2、b1、b2、n1、n2Are all constants;
the discharge probability of the insulating oil spark at the time t is as follows:
the breakdown probability of the oil-impregnated paper at the time t is as follows:
the total failure rate of the distribution transformer is:
Ph(t)＝Ph1(t)+Ph2(t)-Ph1(t)Ph2(t)。
further, obtaining a power distribution network fault rate calculation model according to the electric pole fault rate model, the overhead line fault rate model, the insulator fault rate model and the transformer fault rate model comprises:
P∑＝Max(Pr(t)+Pl(t))+Pg+Ph(t)，t∈[0,ttotal]；
in the formula, P∑Is the total probability of load power loss in the duration of typhoon disaster, Pr(t) is the pole failure rate at time t, Pl(t) is the failure rate at time t of the overhead line, PgIs the flashover probability, P, of a single insulatorh(t) is the failure rate of the transformer at time t.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
Fig. 1 is a flowchart of a method for calculating a failure rate of a power distribution network in a typhoon disaster according to an embodiment of the present invention;
fig. 2 is a connection block diagram of a system for calculating a failure rate of a power distribution network in a typhoon disaster according to an embodiment of the present invention.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
In an embodiment of the present invention, a method for calculating a failure rate of a power distribution network in a typhoon disaster is provided, and fig. 1 is a schematic overall flow chart of the method for calculating a failure rate of a power distribution network in a typhoon disaster provided in the embodiment of the present invention, where the method includes:
establishing a probability density function model representing typhoon intensity based on historical data of typhoon wind speed and rainfall intensity under typhoon disasters;
establishing a probability distribution function model of typhoon duration;
establishing a power distribution network fault rate calculation model under the typhoon disaster based on the probability density function model representing the typhoon intensity and the probability distribution function model representing the typhoon duration;
and calculating the total probability of load power loss within the duration time of the typhoon disaster based on the power distribution network fault rate calculation model.
It can be understood that the existing extreme disaster modeling method driven by the data model in a combined manner is to respectively perform repeated modeling on the same problem by adopting data and physical methods, and realize the fusion of the data model and the physical model through mutual iterative correction, so that the problems of large data demand and insufficient model precision still exist.
The embodiment of the invention provides a method for calculating the fault rate of a power distribution network under an extreme disaster condition, such as a typhoon disaster, which divides the fault rate analysis of the power distribution network under the typhoon disaster into two independent and parallel sub-problems of probability modeling and fault mechanism modeling of meteorological data; fitting historical data of the typhoon disaster to obtain a predicted value of the typhoon intensity and the typhoon duration under the typhoon disaster; the method is characterized in that an analysis method based on a typhoon disaster mechanism is provided for modeling the fault rate, and a comprehensive fault rate model of the power distribution network under the typhoon disaster is obtained by analyzing the influence of the current typhoon intensity and the duration of the typhoon disaster on the fault rate of the power distribution network tower, the overhead line, the insulator and the transformer.
Probability density functions representing typhoon intensity and typhoon duration are respectively established, a power distribution network fault rate calculation model under typhoon disasters is further established, and the total probability of load power loss in the duration of the typhoon disasters is calculated by utilizing the power distribution network fault rate calculation model.
The embodiment of the invention simultaneously considers the uncertainty of typhoon intensity and duration, analyzes the physical principle of different types of faults of the power distribution network caused by typhoon disasters and has higher accuracy. The method is used for modeling the fault rate of the power distribution network, the influence of typhoon intensity and duration on the fault rate of the power distribution network is comprehensively considered, the running state of the power distribution network under the typhoon disaster is completely and accurately described by carrying out detailed modeling on multiple disaster-causing factors and disaster-causing mechanisms of the typhoon disaster, and the precision of the fault rate model of the power distribution network is greatly improved by utilizing the advantage of combined driving of the data model.
On the basis of the embodiment, in the embodiment of the invention, in the modeling process of the typhoon disaster intensity, historical data of characteristic quantities such as typhoon wind speed, rainfall intensity and the like are analyzed, a probability density function representing the typhoon intensity is obtained through fitting, and further, the confidence interval of each characteristic quantity is solved by introducing a condition risk value.
Specifically, establishing a probability density function model representing typhoon intensity based on historical data of typhoon wind speed and rainfall intensity under typhoon disasters comprises the following steps:
in the modeling process of typhoon disaster intensity, the time-varying probability vector V (t) of typhoon wind speed and rainfall intensity is expressed as:
V(t)＝[Vwind(t) Vrain(t)]；
in the formula: vwind(t) is the probability vector of typhoon wind speed at time t, VrainAnd (t) is a probability vector of rainfall intensity at the moment t.
And fitting to obtain a probability density function model rho (V (t)) of V (t) based on historical data of typhoon wind speed and rainfall intensity.
Fitting historical data of typhoon wind speed and rainfall intensity to obtain a probability density function rho (V (t)) of V (t), and further forming a conditional confidence interval with a confidence level beta based on CVaR
The critical values are:
in the formula:
the cut-off value, which is a confidence interval, can be expressed in the form:
in the formula: phi is aup、φlowThe probability that the time t v (t) does not cross the threshold α may be specifically expressed as:
on the basis of the above embodiments, in the embodiment of the present invention, establishing a probability distribution function model of typhoon duration includes:
and establishing a probability distribution function model of the typhoon duration by judging whether the typhoon intensity is reduced to the lowest grade standard at the moment t.
Wherein, the step of establishing the probability distribution function model of the typhoon duration by judging whether the typhoon intensity is reduced to the lowest level standard at the moment t comprises the following steps:
typhoon duration T is expressed as:
T＝tend-tbegin；
in the formula: t is tbeginAt the beginning of a typhoon, tendBoundary value of beta confidence interval at typhoon end time
Obtained by the following formula:
in the formula:
the upper limit of the conditional confidence interval of the typhoon wind speed and the rainfall intensity, VwminIs the lowest level standard of typhoon wind speed, VrminThe standard is the lowest grade standard of rainfall intensity;
in the formula:
respectively is the lower limit of the condition confidence interval of the typhoon wind speed and the rainfall intensity;
the beta confidence interval for typhoon duration T is
On the basis of the above embodiments, in the embodiments of the present invention, based on a probability density function model representing typhoon intensity and a probability distribution function model representing typhoon duration, establishing a power distribution network failure rate calculation model under typhoon disasters includes:
respectively establishing an electric pole fault rate model, an overhead line fault rate model, an insulator fault rate model and a transformer fault rate model;
and obtaining a power distribution network fault rate calculation model according to the electric pole fault rate model, the overhead line fault rate model, the insulator fault rate model and the transformer fault rate model.
It can be understood that, in typhoon weather, the combined action of wind and rain can greatly increase the failure rate of the power distribution network, and the method mainly comprises the following two aspects: the acting force of strong wind on the tower or overhead line exceeds the load capacity of the tower or overhead line, so that the tower is inverted and the line is broken; rainfall can cause the surface resistance value of the insulator to be reduced, so that flashover occurs, and the transformer is also affected with water and damp, thereby causing insulation accidents. Therefore, in the embodiment of the invention, an electric pole fault rate model, an overhead line fault rate model, an insulator fault rate model and a transformer fault rate model are respectively established based on a probability density function model representing typhoon intensity and a probability distribution function model representing typhoon duration, a power distribution network fault rate calculation model is further established, and finally, the total fault rate of the power distribution network under typhoon disasters is calculated according to the power distribution network fault rate calculation model.
On the basis of the above embodiments, in the embodiments of the present invention, the specific process of establishing the electric pole fault rate model is as follows:
in the typhoon disaster duration process, the effective wind speed of the P point on the distribution line at the time t can be expressed as
In the formula: vwind(t) is the eye wind speed at time t, ReyeIs the radius of the wind eye, LPIs the straight line distance from the point P to the center of the typhoon.
The wind load at point P can be represented as the wind load w borne by the wire at time tx(t) wind load w borne by the towers(t) and the wind load w to which the insulator is subjectedz(t)：
In the formula: alpha is the uneven coefficient of the air pressure of the overhead line, muzIs the coefficient of variation of the wind pressure height, muSCIs the form factor of the overhead line, d is the outer diameter of the conductor of the overhead line, lHIn order to realize the horizontal span length,
is the angle between the wind direction and the wire, beta is the wind vibration coefficient, muSIs the wind load size coefficient, A is the projected area of the windward side of the tower structural member, n1Number of insulator strings, n, for single-phase conductors2Number of pieces per insulator string, APThe wind area of each insulator is shown.
The bending moment at any section of the pole body can be expressed as:
in the formula: w is axz(t) is the sum of the wind load of the conductor and the wind load of the insulator, wsv(t) is the combined wind load of the conductor pole tower and the insulator, h1Is the distance from the cross section to the top of the rod,
is the height m from the cross section to the action point of the resultant wind pressure of the rod bodyxFor the additional moment coefficient due to deflection, F is the projected area of the shaft, D0Is a slight diameter of the electric pole; dxIs the diameter of the section of the electric pole.
In the typhoon continuous process, the bending moment of the cross section of the pole body of the electric pole exceeds the bending strength of the cross section of the pole body of the electric pole due to overlarge wind load, and the pole is turned over. To describe the fault rate of the electric pole, a function taking the state of the electric pole as a basic variable is established:
Z1＝R1-S1；
in the formula: r1 is the bending strength of the electric pole, S1 is the internal stress of the electric pole caused by wind load, and is related to wind speed and wind direction;
wherein, R1 is the Gauss distribution that electric pole bending strength obeys following formula:
in the formula: mu.sPIs the mean value of the bending strength of the concrete pole, deltaPIs the standard deviation of the bending strength of the concrete pole, beta and upsilon can be measured through actual operation experience or destructive test, MuChecking the bending moment for the bearing capacity of the concrete pole;
the normal operation probability of the electric pole at the moment t is as follows:
the failure rate of the pole at time t is
On the basis of the above embodiments, in the embodiments of the present invention, during the continuous typhoon, the bending moment of the overhead line exceeds the bending strength thereof due to the excessive wind load, which causes the disconnection. To describe the failure rate of the overhead line, it is first necessary to calculate the overhead line dead weight LGAnd maximum bearing stress LDesm：
In the formula: l isvFor vertical span of overhead lines, G0Mass per unit length of overhead wire, TmThe tension is determined by the type of the overhead line, and K is a safety coefficient;
by analogy with the fault rate modeling process of the electric pole, a function taking the overhead line state as a basic variable can be obtained as shown in the formula, wherein the function can be expressed as:
Z2＝R2-S2；
R2＝LG+LDesm；
in the formula: r2 is the tensile strength of the overhead line, S2 is the internal stress of the overhead line caused by wind load, and is related to wind speed and wind direction;
the failure rate of the overhead line at time t is:
in the formula: mu.sPIs the mean value of the tensile strength of the overhead wire, deltaPIs the standard deviation of the overhead wire tensile strength.
On the basis of the above embodiments, in the embodiments of the present invention, an insulator failure rate model is established:
rainfall critical value A of insulator flashoverζExpressed as:
in the formula: u shapeζThe critical value of the flashover voltage of the insulator is obtained; p is the current ambient air pressure; p0The standard atmospheric pressure is adopted, and a, b and c are constants;
the flashover probability of a single insulator is:
in the formula: f (V)rain(t)) is a probability distribution function of rainfall intensity, and is obtained by the following formula:
on the basis of the above embodiments, in the embodiments of the present invention, the transformer fault rate model includes:
rainfall critical value A of spark discharge of transformer insulating oilζ1And the rainfall critical value A of the punctured oil-impregnated paper2Respectively expressed as:
in the formula: w1The oil-water content of the transformer insulation, W2The moisture content of the transformer oil-immersed paper is measured, and N is the rainfall duration, namely the duration t of the typhoon disastertotal，a1、a2、b1、b2、n1、n2Are all constants;
the discharge probability of the insulating oil spark at the time t is as follows:
the breakdown probability of the oil-impregnated paper at the time t is as follows:
wherein the content of the first and second substances,
the total failure rate of the distribution transformer is:
Ph(t)＝Ph1(t)+Ph2(t)-Ph1(t)Ph2(t)。
on the basis of the above embodiments, in the embodiment of the present invention, obtaining a power distribution network fault rate calculation model according to the pole fault rate model, the overhead line fault rate model, the insulator fault rate model, and the transformer fault rate model includes:
P∑＝Max(Pr(t)+Pl(t))+Pg+Ph(t)，t∈[0,ttotal]；
in the formula, P∑Is the total probability of load power loss in the duration of typhoon disaster, Pr(t) is the pole failure rate at time t, Pl(t) is the failure rate at time t of the overhead line, PgIs the flashover probability, P, of a single insulatorh(t) is the failure rate of the transformer at time t.
The method for calculating the failure rate of the power distribution network under the typhoon disaster provided by the embodiment of the invention is explained in detail below.
Before constructing a probability density function representing typhoon intensity and a probability density distribution function representing typhoon duration, basic information of a power distribution network, including a topological structure, an overhead line model, geographical distribution and the like, needs to be provided; meanwhile, basic information of typhoon, including landing position, running track, speed and the like, is required to be provided. The specific working process is as follows:
the first step is as follows: and loading typhoon historical data, including typhoon wind speed, time sequence change process of rainfall intensity and typhoon duration.
The second step is that: and establishing a statistical model of the typhoon disaster. Historical data of characteristic quantities such as typhoon wind speed and rainfall intensity are analyzed, and a probability density function representing typhoon intensity is obtained through GMM fitting. And further solving a confidence interval of each characteristic quantity by introducing a condition risk value, and obtaining the probability distribution of the typhoon duration by judging whether the typhoon intensity is reduced to be below the lowest level standard (12 levels of typhoon center wind power).
The third step: and establishing a power distribution network fault rate model based on a disaster-causing mechanism. And (4) considering a disaster mechanism of the typhoon disaster, establishing a fault rate model of multiple elements such as an electric pole, an overhead line, an insulator, a distribution transformer and the like, and obtaining the total fault rate of the distribution network under the typhoon disaster. Because under the typhoon weather, the combined action of wind, rain can increase the fault rate of distribution network by a wide margin, mainly include following two aspects: the acting force of strong wind on the tower or overhead line exceeds the load capacity of the tower or overhead line, so that the tower is inverted and the line is broken; rainfall can cause the surface resistance value of the insulator to be reduced, so that flashover occurs, and the transformer is also affected with water and damp, thereby causing insulation accidents.
The invention has the beneficial effects that:
(1) a statistical model is established for the typhoon intensity and duration, multiple disaster concurrences are considered, and the joint action of typhoon and rainstorm can be fully reflected;
(2) the power distribution network fault rate modeling method under the typhoon disaster comprehensively considers the damage effect of the typhoon disaster on different elements of the power distribution network, and has higher accuracy;
(3) with the increasing abundance of the types of the elements of the active power distribution network, the requirements of the active power distribution network can be adapted by supplementing a fault rate model of a novel element (the element in the embodiment of the invention mainly comprises an electric pole, an overhead line, an insulator and a distribution transformer), and the expandability is realized;
in short, the method only needs to provide typhoon historical data and basic information of the power distribution network, predicted values of typhoon intensity and duration are obtained through fitting, different fault rate models are built for different elements of the power distribution network, the fault rates of all the elements under the typhoon disaster are obtained, the total fault rate of the power distribution network is obtained through summation finally, modeling of the fault rate of the power distribution network under the typhoon disaster driven by the data models in a combined mode is achieved, and the accuracy of the existing models can be greatly improved.
Referring to fig. 2, in another embodiment of the present invention, a system for calculating a failure rate of a power distribution network in a typhoon disaster is provided, and the system is used for implementing the method in the foregoing embodiments. Therefore, the description and definition in the foregoing embodiments of calculating the failure rate of the power distribution network in the typhoon disaster can be used for understanding the execution modules in the embodiments of the present invention. Fig. 2 is a schematic view of an overall structure of a system for calculating a failure rate of a power distribution network in a typhoon disaster, according to an embodiment of the present invention, where the system includes:
the first establishing module 21 is used for establishing a probability density function model representing typhoon intensity based on historical data of typhoon wind speed and rainfall intensity under typhoon disasters;
a second establishing module 22, configured to establish a probability distribution function model of the typhoon duration;
the third establishing module 23 is configured to establish a power distribution network fault rate calculation model under the typhoon disaster based on the probability density function model representing the typhoon intensity and the probability distribution function model representing the typhoon duration;
and the calculating module 24 is used for calculating the total probability of load power loss within the duration time of the typhoon disaster based on the power distribution network fault rate calculating model.
The system for calculating the failure rate of the power distribution network in the typhoon disaster provided by the embodiment of the invention corresponds to the method for calculating the failure rate of the power distribution network in the typhoon disaster provided by the embodiment, and the relevant technical features of the system for calculating the failure rate of the power distribution network in the typhoon disaster can refer to the relevant technical features of the method for calculating the failure rate of the power distribution network in the typhoon disaster provided by the embodiment, and are not repeated herein.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (2)
1. A method for calculating the fault rate of a power distribution network under a typhoon disaster is characterized by comprising the following steps:
establishing a probability density function model representing typhoon intensity based on historical data of typhoon wind speed and rainfall intensity under typhoon disasters;
establishing a probability distribution function model of typhoon duration;
establishing a power distribution network fault rate calculation model under the typhoon disaster based on the probability density function model representing the typhoon intensity and the probability distribution function model representing the typhoon duration;
calculating the total probability of load power loss in the duration time of the typhoon disaster based on the power distribution network fault rate calculation model;
the establishing of the probability distribution function model of the typhoon duration comprises the following steps:
establishing a probability distribution function model of typhoon duration by judging whether the typhoon intensity is reduced to the lowest grade standard at the moment t; wherein, the step of establishing the probability distribution function model of the typhoon duration by judging whether the typhoon intensity is reduced to the lowest level standard at the moment t comprises the following steps:
typhoon duration T is expressed as:
T＝tend-tbegin；
in the formula: t is tbeginAt the beginning of a typhoon, tendBoundary value of beta confidence interval at typhoon end time
Obtained by the following formula:
in the formula:
the upper limit of the conditional confidence interval of the typhoon wind speed and the rainfall intensity, VwminIs the lowest level standard of typhoon wind speed, VrminThe standard is the lowest grade standard of rainfall intensity;
in the formula:
respectively is the lower limit of the condition confidence interval of the typhoon wind speed and the rainfall intensity;
the beta confidence interval for typhoon duration T is
The establishing of the power distribution network fault rate calculation model under the typhoon disaster based on the probability density function model representing the typhoon intensity and the probability distribution function model representing the typhoon duration comprises the following steps:
respectively establishing an electric pole fault rate model, an overhead line fault rate model, an insulator fault rate model and a transformer fault rate model;
obtaining a power distribution network fault rate calculation model according to the electric pole fault rate model, the overhead line fault rate model, the insulator fault rate model and the transformer fault rate model; wherein the content of the first and second substances,
the establishing of the electric pole fault rate model comprises the following steps:
establishing a function taking the state of the electric pole as a basic variable:
Z1＝R1-S1；
in the formula: r1 is the bending strength of the electric pole, S1 is the internal stress of the electric pole caused by wind load, and is related to wind speed and wind direction;
wherein, R1 is the Gauss distribution that electric pole bending strength obeys following formula:
in the formula: mu.sPIs the mean value of the bending strength of the concrete pole, deltaPIs the standard deviation of the bending strength of the concrete pole, beta and upsilon can be measured through actual operation experience or destructive test, MuChecking the bending moment for the bearing capacity of the concrete pole;
the normal operation probability of the electric pole at the moment t is as follows:
the failure rate of the pole at time t is
The establishing of the overhead line fault rate model comprises the following steps:
calculating the self-weight L of the overhead lineGAnd maximum bearing stress LDesm：
In the formula: l isvFor vertical span of overhead lines, G0Mass per unit length of overhead wire, TmThe tension is determined by the type of the overhead line, and K is a safety coefficient;
the function with the overhead line state as the basic variable is as follows:
Z2＝R2-S2；
R2＝LG+LDesm；
in the formula: r2 is the tensile strength of the overhead line, S2 is the internal stress of the overhead line caused by wind load, and is related to wind speed and wind direction;
the failure rate of the overhead line at the time t is as follows:
in the formula: mu.sPIs the mean value of the tensile strength of the overhead wire, deltaPIs the standard deviation of the tensile strength of the overhead line;
establishing an insulator fault rate model:
rainfall critical value of insulator flashover
Expressed as:
in the formula:
the critical value of the flashover voltage of the insulator is obtained; p is the current ambient air pressure; p0The standard atmospheric pressure is adopted, and a, b and c are constants;
the flashover probability of a single insulator is:
in the formula: f (V)rain(t)) is a probability distribution function of rainfall intensity, and is obtained by the following formula:
the transformer fault rate model comprises:
rainfall critical value of spark discharge of transformer insulating oil
And the rainfall critical value of the broken oil-impregnated paper
Respectively expressed as:
in the formula: w1The oil-water content of the transformer insulation, W2The moisture content of the transformer oil-immersed paper is measured, and N is the rainfall duration, namely the duration t of the typhoon disastertotal，a1、a2、b1、b2、n1、n2Are all constants;
the discharge probability of the insulating oil spark at the time t is as follows:
the breakdown probability of the oil-impregnated paper at the time t is as follows:
the total failure rate of the distribution transformer is:
Ph(t)＝Ph1(t)+Ph2(t)-Ph1(t)Ph2(t)；
the method for obtaining a power distribution network fault rate calculation model according to the electric pole fault rate model, the overhead line fault rate model, the insulator fault rate model and the transformer fault rate model comprises the following steps:
PΣ＝Max(Pr(t)+Pl(t))+Pg+Ph(t)，t∈[0,ttotal]；
in the formula, PΣIs the total probability of load power loss in the duration of typhoon disaster, Pr(t) is the pole failure rate at time t, Pl(t) is the failure rate at time t of the overhead line, PgIs the flashover probability, P, of a single insulatorh(t) is the failure rate of the transformer at time t.
2. The method for calculating the failure rate of the power distribution network in the typhoon disaster according to the claim 1, wherein the establishing of the probability density function model representing the typhoon intensity based on the historical data of the typhoon wind speed and the rainfall intensity in the typhoon disaster comprises:
the time-varying probability vector v (t) for typhoon wind speed and rainfall intensity is expressed as:
V(t)＝[Vwind(t)Vrain(t)]；
in the formula: vwind(t) is the probability vector of typhoon wind speed at time t, Vrain(t) is a probability vector of rainfall intensity at time t;
and fitting historical data of typhoon wind speed and rainfall intensity to obtain a probability density function rho (V (t)) of V (t).
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