CN115128395A - Voltage sag source positioning method and device - Google Patents
Voltage sag source positioning method and device Download PDFInfo
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Abstract
The invention discloses a method and a device for positioning a voltage sag source, wherein the method comprises the following steps: constructing impedance matrixes of a plurality of network nodes on the electric network line, and setting a plurality of monitoring points based on the impedance matrixes; respectively extracting observable line sets of each monitoring point, and determining a first fault line set corresponding to the observable line of each monitoring point; judging whether a voltage sag source is positioned at the upstream or the downstream of a monitoring point according to the reactive change condition of the monitoring point, and determining a second fault line set corresponding to the voltage sag source; taking intersection of the first fault line set and the second fault line set, and determining a third fault line set corresponding to the voltage sag source; and determining the position of the voltage sag source by adopting a sparrow search algorithm according to the third fault line set. The technical scheme of the invention comprehensively utilizes multiple criteria of the observable domain of the monitoring point, the dip source direction and the like, eliminates the influence of non-fault points as much as possible, can effectively improve the fault positioning efficiency and improve the accuracy of the positioning result.
Description
Technical Field
The invention relates to the technical field of power faults, in particular to a method and a device for positioning a voltage sag source.
Background
Voltage sag is a phenomenon often encountered in power systems, and has risen to be an important power quality problem, causing common attention of power companies and power consumers in various countries in the world. Transmission or distribution system faults in a utility grid are a major cause of voltage sags. The position of the sag fault source is accurately positioned, so that on one hand, the sag responsibilities of both power supply and power utilization parties are distinguished, and disputes are coordinated; on the other hand, the fault clearing time of the power company can be greatly shortened, and the power supply reliability is improved. Most of the traditional voltage sag source positioning methods judge that the fault position is located at the upstream or the downstream of a monitoring point according to the impedance at the monitoring point and the change of the measured information such as voltage, current and power, and the judgment of the specific position of the sag source is not realized.
Disclosure of Invention
In order to solve the above technical problem, in one aspect, the present invention provides a method for positioning a voltage sag source, including:
constructing impedance matrixes of a plurality of network nodes on a power grid line according to electrical parameters of a power grid, and setting a plurality of monitoring points on the power grid line based on the impedance matrixes;
for each monitoring point, respectively extracting observable line sets of each monitoring point according to the monitoring point number after voltage sag monitoring, taking intersection of the observable line sets among the monitoring points, and determining a first fault line set corresponding to the observable line of each monitoring point;
for each monitoring point, judging whether a voltage sag source is positioned at the upstream or the downstream of the monitoring point according to the reactive power change condition of the monitoring point, extracting corresponding upstream lines or downstream lines of the voltage sag source on a power grid line according to the judgment result of the position of the voltage sag source, taking intersection of fault lines of each monitoring point, and determining a second fault line set corresponding to the voltage sag source;
taking an intersection of the first fault line set and the second fault line set, and determining a third fault line set corresponding to the voltage sag source;
and determining a monitoring point number corresponding to the voltage sag source according to the third fault line set, and determining the position of the voltage sag source by adopting a sparrow search algorithm by taking the minimum sum of the error values of the theoretical calculated value of the voltage after the fault and the actual observed value corresponding to the monitoring point number as a target.
Firstly, an impedance matrix of a plurality of network nodes on a power grid line is constructed according to electrical parameters of the power grid, and a plurality of monitoring points are arranged on the power grid line based on the impedance matrix, wherein the impedance matrix comprises the following steps:
establishing a functional relation between the fault distance between the fault point on the power grid line and the monitoring point on the power grid line and the sag amplitude of the monitoring point, wherein the process is as follows:
if the system has a three-phase symmetric short-circuit fault at node n, the voltage at node m may be given by the fault occurring at node n:
wherein,
representing the voltage before failure, Δ V, at node m mn Representing the amount of change in the voltage at node m due to a fault at node n;
the condition that the three-phase voltage at the node m is reduced due to the fault of the node n is as follows:
wherein, V sag (m, n) represents the voltage sag of node m at the time of node failure,
representing the voltage before failure of node n, Z mn Representing the mutual impedance between node m and node n, Z nn Representing the self-impedance of node n.
In practice, the probability of failure at a node is very small. Most short circuit faults occur along the line. The fault occurs at the p-point location in the middle of the line as shown in figure 1. The voltage sag at node k caused by the fault occurring at a location along line p is calculated as follows:
the new impedance due to this fault location p will be calculated from node k.
Z kp ＝(1-λ)×Z km +λ×Z kn
Z pp ＝(1-λ) 2 ×Z mm +λ 2 ×Z nn +2λ(1-λ)×Z mn +λ(1-λ)×z mn
Wherein L is mn Representing the distance between two associated nodes m and n in the network;
L mp represents the distance between node m and the point of failure p;
Z kp represents the transmission impedance between node k and fault point p;
Z pp represents the self-impedance of the fault point p;
Z mn representing the mutual impedance between node m and node n.
The voltage before p-point failure is
The relationship between the voltage at the node k and the fault distance can be solved by the simultaneous expression. The relationship between the voltage amplitude of each bus and the fault distance in the system during the three-phase short-circuit fault is deduced, and the relationship between the voltage amplitude of each bus and the fault distance can still be deduced when the system has asymmetric short-circuit faults including two-phase short-circuit, two-phase grounding short-circuit and single-phase grounding short-circuit.
Secondly, analyzing critical fault points of monitoring points corresponding to different fault types on each line under a preset threshold value. The process of solving the critical failure point is as follows:
when a short-circuit fault occurs in the system, the node voltage in the system is reduced along with the short-circuit fault, and if the voltage of a certain node is reduced to a preset threshold value, the node is a critical fault point. And the position of the node can be obtained by combining the relation of the distance between the front node and the fault point.
f(λ)＝U sag (λ)-U t ＝0
In the formula of U t Indicating a predetermined voltage threshold. The formula can be solved iteratively by using a cow pulling method.
Where k denotes the number of iterations, f' (λ) k ) Denotes f (λ) k ) The derivative of (c).
But due to f (lambda) k ) The method is a complex nonlinear function, the derivation process is difficult, and in order to obtain a faster convergence rate and a more accurate result, a better iterative algorithm is adopted, and the iterative formula is as follows:
when asymmetric faults occur in the system, the amplitude values of three-phase voltages of the nodes are different, and for this reason, the amplitude value of any one phase voltage in the three phases is regulated to be reduced to U in the threshold value t It is indicated that voltage sag occurs at this point, i.e. three-phase voltageThe minimum phase of the amplitude is used as the basis for determining the voltage sag.
At this time, the expression of the voltage sag equivalent amplitude is:
U sageq ＝min(U sagA (λ),U sagB (λ),U sagC (λ))
the critical fault point of the node when the asymmetric fault occurs can be obtained by the above formula.
And finally, determining an observable matrix of each monitoring point and reasonably and effectively arranging limited monitoring points on the basis of obtaining critical fault points of the monitoring points corresponding to different fault types on each line.
The node MRA (Monitor read Area, MRA) is an observable region of a node, and refers to a fault region that can be monitored by a monitoring point when a voltage dip occurs in the monitoring point due to a short-circuit fault in a line in a system. The arrangement of the voltage sag monitoring points must meet the observability of the faults of the whole network, so that the limited monitoring points are required to be reasonably and effectively configured, and the MRA combined with the limited monitoring points can cover the whole network. The MRA matrix formed by the combination of the monitoring points can be represented as:
wherein the total number of nodes of the system is represented by N, the total number of fault points of the system is represented by P, and the voltage of the i node when the fault point j has a fault is represented by U ij And (4) showing. When U is formed ij Below a set threshold U t Time M (i,j) 1 indicates that a voltage sag has occurred at node i. When short-circuit faults of different types occur, the MRA of each monitoring point is changed, and the observable matrix M corresponding to the single-phase grounding short circuit, the two-phase short circuit and the three-phase short circuit (1) 、M (1，1) 、M (2) 、M (3) 。
If N nodes are arranged in the network, the setting condition of the monitoring point in the network can be represented by using an N-dimensional state variable x
If there is an important load node in the network, when the node has to set a monitoring point, its corresponding element may be set to 1 all the time in the configuration process. The configuration of the voltage sag monitoring points takes the minimum total number of the monitoring points as an optimization target, and when short-circuit faults occur in the network, at least b monitoring points need to have voltage sag. According to the method, a monitoring point configuration model is divided into a target function part and a constraint condition part. The objective function is denoted by minf (x), which is equal to the sum of all node state quantities. The constraint conditions ensure that all short-circuit faults of the whole network can be observed.
An objective function:
constraint conditions are as follows:
in the formula P (1) 、P (1，1) 、P (2) 、P (3) Respectively correspond to observable matrixes
Number of failure points of b 1 、b 2 、b 3 、b 4 The number of the monitoring points which are set corresponding to different fault types and can generate voltage sag at least is respectively. The configuration model of the monitoring point is actually a problem of integer (0-1) linear programming, and the configuration model can be solved by using a YALMIP toolbox in MATLAB, so as to obtain a configuration scheme of the voltage sag monitoring point. After the monitoring point configuration scheme is determined, observable line sets J of all monitoring points are respectively extracted according to the monitoring point numbers for monitoring sag Lm And the intersection is taken to finally obtain a first fault line set J extracted according to the observable lines of the monitoring points L 。
Judging whether a voltage sag source is positioned at the upstream or the downstream of the monitoring point according to the reactive change condition of the monitoring point, extracting corresponding upstream lines or downstream lines of the voltage sag source on a power grid line according to the judgment result of the position of the voltage sag source, taking intersection of fault lines of the monitoring points, and determining a second fault line set corresponding to the voltage sag source, wherein the judgment result comprises the following steps:
extracting upstream and downstream power grid lines corresponding to the monitoring points according to the electrical parameters corresponding to each monitoring point on the power grid lines;
each monitoring point in the power grid line is analyzed (theoretical or simulation analysis), and lines located at the upstream and downstream of the monitoring point are extracted and stored. For monitor point m, let its upstream line sequence be J Vup-m And the downstream line sequence is J Vdown-m . And then, judging whether the sag source is positioned at the upstream or the downstream of the sag source according to the reactive change condition of the monitoring point. The idle work before the temporary drop of the monitoring point m is Q m The idle work in the temporary reduction process is Q fm Then, the determination can be made by the following formula.
Finally, for each monitoring point m, extracting corresponding upstream or downstream lines according to the sag source azimuth judgment result, and taking intersection for possible lines of each monitoring point to finally obtain a second fault line set J extracted according to sag azimuth judgment V 。
Determining a monitoring point number corresponding to the voltage sag source according to the third fault line set, and determining the position of the voltage sag source by adopting a sparrow search algorithm with the goal that the sum of the error values of the theoretical calculated value of the voltage after the fault corresponding to the monitoring point number and the actual observed value is minimum, wherein the step comprises the following steps:
after the monitoring point number corresponding to the voltage sag source is determined according to the third fault line set, the step of determining the position of the voltage sag source by adopting a sparrow search algorithm comprises the following steps:
firstly, the optimization variables are set as follows, namely a fault occurrence branch l (discrete type), a relative distance lambda (continuous type) between a fault point and a first section of the fault branch and a transition resistance R f (continuous type) as an optimization variable;
secondly, the sum of the error value of the theoretical calculation value of the voltage after the fault at the monitoring point and the actual observation value is minimum as a target, specifically
Wherein, Δ u m (l,λ,R f ) The relative distance between the upper part of the fault branch and the head end of the fault branch is lambda, and the transition resistance is R f The voltage error value at the mth monitoring point; m is the number of monitoring points.
In another aspect, the present application provides a voltage sag source positioning device, including:
the system comprises a power grid network construction module, a power grid monitoring module and a monitoring module, wherein the power grid network construction module is used for constructing impedance matrixes of a plurality of network nodes on a power grid line according to electrical parameters of a power grid, and setting a plurality of monitoring points on the power grid line based on the impedance matrixes;
the first fault line set determining module is used for respectively extracting observable line sets of the monitoring points according to the monitoring point numbers after the voltage sag is monitored for the monitoring points, taking intersection sets of the observable line sets among the monitoring points, and determining a first fault line set corresponding to the observable line sets of the monitoring points;
the second fault line set determining module is used for judging whether a voltage sag source is positioned at the upstream or the downstream of each monitoring point according to the reactive power change condition of the monitoring point, extracting the corresponding upstream line or the downstream line of the voltage sag source on the power grid line according to the judgment result of the position of the voltage sag source, taking the intersection of the fault lines of each monitoring point and determining a second fault line set corresponding to the voltage sag source;
a third fault line set determining module, configured to obtain an intersection from the first fault line set and the second fault line set, and determine a third fault line set corresponding to the voltage sag source;
and the voltage sag source determining module is used for determining a monitoring point number corresponding to the voltage sag source according to the third fault line set, and determining the position of the voltage sag source by adopting a sparrow searching algorithm by taking the minimum sum of the error values of the theoretical calculated value of the voltage after the fault corresponding to the monitoring point number and the actual observed value as a target.
In another aspect, an embodiment of the present invention further provides an electronic device, which includes a processor, a memory, and a computer program stored in the memory and capable of running on the processor, and when executed by the processor, the computer program implements the steps of the method for positioning a voltage sag source.
The technical scheme of the invention constructs impedance matrixes of a plurality of network nodes on a power grid line according to the electrical parameters of a power grid, and sets a plurality of monitoring points on the power grid line based on the impedance matrixes; for each monitoring point, respectively extracting observable line sets of the monitoring points according to the monitoring point numbers after voltage sag is monitored, taking intersection of the observable line sets among the monitoring points, and determining a first fault line set corresponding to the observable line of each monitoring point; for each monitoring point, judging whether a voltage sag source is positioned at the upstream or the downstream of the monitoring point according to the reactive change condition of the monitoring point, extracting corresponding upstream lines or downstream lines of the voltage sag source on a power grid line according to the judgment result of the position of the voltage sag source, taking intersection of fault lines of each monitoring point, and determining a second fault line set corresponding to the voltage sag source; taking intersection of the first fault line set and the second fault line set, and determining a third fault line set corresponding to the voltage sag source; and determining a monitoring point number corresponding to the voltage sag source according to the third fault line set, and determining the position of the voltage sag source by adopting a sparrow search algorithm by taking the minimum sum of the error values of the theoretical calculated value of the voltage after the fault corresponding to the monitoring point number and the actual observed value as a target. The technical scheme of the invention comprehensively utilizes multiple criteria of the observable domain of the monitoring point, the dip source direction and the like, eliminates the influence of non-fault points as much as possible, can effectively improve the fault positioning efficiency and improve the accuracy of the positioning result.
Drawings
Fig. 1 is a flowchart illustrating steps of a method for positioning a voltage sag source according to an embodiment of the present invention;
fig. 2 is a schematic diagram illustrating a distance definition of a grid line fault according to an embodiment of the present invention;
fig. 3 is a schematic configuration diagram of a power grid monitoring point according to an embodiment of the present invention;
FIG. 4 is a flow chart of a method for positioning a voltage sag source;
fig. 5 is a flowchart of a method for accurately positioning a fault point according to an embodiment of the present invention;
Detailed Description
Because the power grid fault is the main cause of sag, the sag source is positioned at the fault point of the power grid in most cases, and at the moment, various methods capable of realizing the positioning of the power grid fault can be used for positioning the sag fault source. Methods for grid fault location can be broadly divided into two categories: one is wide-area fault section positioning which widely utilizes a plurality of line terminals or fault indicators and is suitable for regional power grids with higher automation level; one is a fault distance measuring method for calculating fault distance by using a small amount of feeder outlet electric quantity information, and is suitable for a power grid with low automation level. Because the power quality monitoring points are limited nodes in the power grid, a distance measurement method is needed for positioning the voltage sag fault source. The methods mainly comprise a traveling wave method, an impedance method, a method based on load flow calculation, a method based on a fault distance distribution function, an intelligent algorithm based on data processing and the like. The traveling wave method requires installation of expensive precision measuring devices, is expensive, and has a problem in that accuracy is disturbed when the network structure is complicated. The impedance method is simple in principle and low in investment, but is easily influenced by line impedance, load and power supply parameters. The method based on load flow calculation needs to estimate the load flow, the fault resistance, the load power and the like before the fault, and the accuracy of estimation of the method will influence the accuracy of the positioning result. The positioning method based on the fault distance distribution function generally searches for a fault section through fitting methods such as a least square method and pattern recognition, but the fitting method generally has a large error with an actual fault distance. Intelligent algorithms based on data processing require a large amount of actual fault information to train algorithm rules, but in practice there is limited data available for learning and training. Therefore, a sag fault positioning method which can meet the positioning accuracy requirement and has lower requirement on monitoring node configuration is needed, and the practicability and robustness of positioning theory research are improved to assist operation and maintenance of faults in practical engineering.
In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description thereof. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Fig. 1 is a flowchart illustrating steps of a method for positioning a voltage sag source according to an embodiment of the present invention, where the method includes the following steps:
forming a network node impedance matrix based on IEEE33 node power distribution network model parameters, calculating to obtain the voltage of a monitoring point when each node fails through a voltage sag matrix, judging whether the failure point can be observed according to the relationship between the voltage of the monitoring point and a set threshold value to form a node sag matrix, and then optimizing a monitoring point configuration scheme. The configuration model of the monitoring point is actually a problem of integer (0-1) linear programming, and the configuration model can be solved by using a YALMIP toolbox in MATLAB, so as to obtain a configuration scheme of the voltage sag monitoring point.
102, respectively extracting an observable line set of each monitoring point according to the number of the monitoring point after the voltage sag is monitored, taking an intersection of the observable line sets among the monitoring points, and determining a first fault line set corresponding to the observable line of each monitoring point;
after the monitoring point configuration scheme is determined, observable line sets J of all monitoring points are respectively extracted according to the monitoring point numbers for monitoring sag Lm And the intersection is taken to finally obtain a first fault line set J extracted according to the observable lines of the monitoring points L 。
103, for each monitoring point, judging whether a voltage sag source is positioned at the upstream or the downstream of the monitoring point according to the reactive power change condition of the monitoring point, extracting the corresponding upstream line or the downstream line of the voltage sag source on the power grid line according to the judgment result of the position of the voltage sag source, taking the intersection of the fault lines of each monitoring point, and determining a second fault line set J corresponding to the voltage sag source L ；
Step 2: an IEEE33 node power distribution network simulation model based on MATLAB-SIMULINK building standard is provided, fig. 2 is a schematic diagram of a power grid line fault distance definition provided by an embodiment of the present invention, fig. 3 is a schematic diagram of configuration of power grid monitoring points provided by an embodiment of the present invention, and monitoring points are configured at 6 nodes, total number of which is 1,2, 5, 19, 23, and 26 in the embodiment of the present invention. For each monitoring point, judging whether the sag source is positioned at the upstream or the downstream of the monitoring point according to the reactive change condition of the monitoring point, and taking intersection of possible lines of each monitoring point, thereby obtaining a second fault line set J extracted according to the sag direction judgment V ；
104, taking an intersection of the first fault line set and the second fault line set, and determining a third fault line set corresponding to the voltage sag source;
and 3, step 3: in order to eliminate the influence of non-fault points as much as possible, the observable domain of the monitoring points is combined with the upstream and downstream positioning methods of the voltage sag source, and a sag fault source positioning method based on multiple criteria is provided, and a flow chart is shown in fig. 4. For the first fault line set J obtained in the step 1 L And the second fault line set J obtained in the step 2 V Taking the intersection to finally obtain a third fault line set J to be inspected;
and 105, determining a monitoring point number corresponding to the voltage sag source according to the third fault line set, and determining the position of the voltage sag source by adopting a sparrow search algorithm by taking the minimum sum of the error values of the theoretical calculated value of the voltage after the fault corresponding to the monitoring point number and the actual observed value as a target.
And on the basis of the third fault line set J, the initial position of the fault source can be obtained, the minimum sum of the theoretical calculated value of the voltage after the fault at the monitoring point and the error value of the actual observed value is taken as the target, after the number of the monitoring point corresponding to the voltage sag source is determined according to the third fault line set, the accurate positioning of the fault source is further solved by utilizing an improved sparrow search algorithm, and the flow of the accurate positioning method of the fault point is shown in the attached figure 5. The method for determining the position of the voltage sag source by adopting a sparrow search algorithm comprises the following steps:
firstly, the optimization variables are set as follows, namely a fault occurrence branch l (discrete type), a relative distance lambda (continuous type) between a fault point and a first section of the fault branch and a transition resistance R f (continuous type) as an optimization variable;
secondly, the sum of the error value of the theoretical calculation value and the actual observation value of the voltage after the fault at the monitoring point is minimum as the target, specifically
Wherein, Δ u m (l,λ,R f ) The relative distance between the upper part of the fault branch and the head end of the fault branch is lambda, and the transition resistance is R f The voltage error value at the mth monitoring point; m is the number of monitoring points.
Because the method is greatly influenced by network parameters, when the network scale is large, in order to reduce the influence of inaccurate network parameters on the result, the weight can be calculated according to the amplitude of the lowest phase of the voltage three-phase voltage of each monitoring point, the lower the amplitude is, the larger the weight is, which means that the lower the voltage of the monitoring point is, the larger the attached weight is, the effect of amplifying the voltage of the monitoring point close to the fault point as much as possible, and meanwhile, the interference of the monitoring point far away from the fault point on the positioning result is reduced. When the network size is small, the weight of each monitoring point can be 1.
At this time, the formula is rewritten as
In the formula, w is a weight, which can be adjusted according to actual conditions, and the value range is 0-1.
The constraint condition is
In the formula, R lim For the upper limit of the transition resistance, 100 Ω is set in the present invention.
For the hybrid optimization problem, an improved sparrow search algorithm (MSSSA) is adopted for solving, and the accurate position of the fault source can be known by solving the value of lambda.
The improved sparrow search algorithm (MSSSA) is improved on the basis of the Sparrow Search Algorithm (SSA). The positions of sparrow individuals are initialized by using Circle mapping, so that the diversity of the initial population is increased. And the position updating strategy of the discoverer is improved by combining a butterfly flight mode in a Butterfly Optimization Algorithm (BOA), and the global exploration capability of the algorithm is enhanced. Therefore, compared with a Sparrow Search Algorithm (SSA), the method has better convergence and solving precision, and the global optimization capability is greatly improved.
The principle of the sparrow search algorithm is as follows: suppose that N sparrows exist in the D dimension solution space and the ith sparrow is X in the D dimension solution space i ＝[x i1 ,x i2 ,…,x id ]With a fitness value of
A part of sparrows with the best positions in each iteration are selected as discoverers, generally account for 10% -20% of the population, the rest are selected as addicts, and the reconnaissance persons randomly select 10% -20% of the whole population.
The location update formula for the discoverer is as follows:
where t represents the current iteration number, j ═ 1,2, …, d. iter max The maximum number of iterations is indicated,
indicating the position of the ith sparrow in the jth dimension, alpha e (0,1) is a random number,
is a value of the early warning value,
for the safety value, Q is a random number following a normal distribution, L is 1 × d, and the matrix has all element values of 1. When R is 2 If ST is less than the above range, it means that there is no natural enemy around the area, and the finder will perform an extensive search. On the contrary, the petunia are found, and all sparrows are flown to other safe places to forage.
The location update formula for the enrollee is as follows:
wherein, X worst Indicating the global worst position for the t-th iteration,
representing the optimal position of the discoverer in the t +1 th iteration, A is a matrix with 1 x d and randomly assigned values of 1 or-1, and A + ＝A T (AA T ) -1 . When i is greater than N/2, the less well-positioned subscriber is in a state of being very hungry, and needs to fly to other places to feed.
The scout position updating formula is as follows:
wherein,
for the current global optimal position, beta is a step size control parameter, and is a normally distributed random number with a mean value of 0 and a variance of 1.
Is a random number, f i Representing the value of individual fitness f g To an optimum fitness value, f ω And the value is the worst fitness value, and epsilon is the minimum constant, so that the condition that the denominator is zero is prevented.
Initializing the sparrow population by using Circle chaotic mapping, wherein the expression is as follows:
where i represents a dimension.
Introducing a global search stage location updating strategy of the BOA to improve a location updating formula of a finder in the SSA, wherein the improved location updating mode is shown as the following formula:
in the improved position updating formula, on one hand, the sparrow individuals can exchange information with the optimal individuals during each iteration, so that the information of the current optimal solution is fully utilized, and the defect that the original algorithm lacks information exchange among individuals is overcome; on the other hand, the introduction of the BOA expands the search space to some extent.
Fig. 4 shows a flowchart of a voltage sag source positioning method provided by an embodiment of the present invention, where a possible faulty line set of a voltage sag source, that is, a first faulty line set J, is extracted from observable lines at monitoring points L And judging and extracting a possible fault line set of the voltage sag source according to the sag azimuth, namely a second fault line set J V For the first fault lineCollection J L And a second set of faulty wires J V And taking the intersection to obtain a possible fault line set J (a third fault line set) of the voltage sag source. The method provided by the invention can comprehensively utilize multiple criteria of observable domains, dip source orientations, fault types and the like of the monitoring points, eliminate the influence of non-fault points as much as possible, and effectively improve the fault positioning efficiency and the accuracy of positioning results. Firstly, a possible fault line set J extracted according to a line observable at a monitoring point is obtained through the analysis of the observable domain at the monitoring point L Judging the extracted possible fault line set J by the upstream and downstream positions of the sag source V Taking J L And J V The intersection of (a) results in a set J of possible faulty wires. In addition, the precise position of the fault source is solved by adopting an improved sparrow search algorithm (MSSSA), and a cyclic traversal process of a possible fault point is avoided. The positions of sparrow individuals are initialized by using Circle mapping, so that the diversity of the initial population is increased. And the position updating strategy of the discoverer is improved by combining a butterfly flight mode in a Butterfly Optimization Algorithm (BOA), and the global exploration capability of the algorithm is enhanced. Therefore, compared with a Sparrow Search Algorithm (SSA), the method has better convergence and solving precision, the global optimization capability is greatly improved, and compared with other algorithms, the method has the characteristics of high search precision and strong robustness.
In another aspect, the present application provides a voltage sag source positioning device, including:
the power grid network construction module is used for constructing impedance matrixes of a plurality of network nodes on a power grid line according to electrical parameters of a power grid, and setting a plurality of monitoring points on the power grid line based on the impedance matrixes;
the first fault line set determining module is used for respectively extracting the observable line sets of the monitoring points according to the monitoring point numbers after the voltage sag is monitored for the monitoring points, taking the intersection of the observable line sets among the monitoring points and determining a first fault line set corresponding to the observable line of each monitoring point;
the second fault line set determining module is used for judging whether a voltage sag source is positioned at the upstream or the downstream of each monitoring point according to the reactive power change condition of the monitoring point, extracting the corresponding upstream line or the downstream line of the voltage sag source on the power grid line according to the judgment result of the position of the voltage sag source, taking the intersection of the fault lines of each monitoring point and determining a second fault line set corresponding to the voltage sag source;
a third fault line set determining module, configured to obtain an intersection from the first fault line set and the second fault line set, and determine a third fault line set corresponding to the voltage sag source;
and the voltage sag source determining module is used for determining a monitoring point number corresponding to the voltage sag source according to the third fault line set, and determining the position of the voltage sag source by adopting a sparrow searching algorithm by taking the minimum sum of the error values of the theoretical calculated value of the voltage after the fault corresponding to the monitoring point number and the actual observed value as a target.
The voltage sag source positioning device provided by the embodiment of the invention can comprehensively utilize multiple criteria such as an observable domain of a monitoring point, a sag source position, a fault type and the like, eliminate the influence of non-fault points as much as possible, and effectively improve the fault positioning efficiency and the accuracy of a positioning result.
In another aspect, an embodiment of the present invention further provides an electronic device, which includes a processor, a memory, and a computer program stored on the memory and capable of running on the processor, and when executed by the processor, the computer program implements the steps of the method for positioning a voltage sag source.
While preferred embodiments of the present invention have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "include", "including" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or terminal device including a series of elements includes not only those elements but also other elements not explicitly listed or inherent to such process, method, article, or terminal device. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or terminal that comprises the element.
The voltage sag source positioning method and the voltage sag source positioning device provided by the present invention are described in detail above, and specific examples are applied in the present document to explain the principle and the implementation of the present invention, and the description of the above embodiments is only used to help understand the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (8)
1. A method for locating a voltage sag source, comprising:
constructing impedance matrixes of a plurality of network nodes on a power grid line according to electrical parameters of a power grid, and setting a plurality of monitoring points on the power grid line based on the impedance matrixes;
for each monitoring point, respectively extracting an observable line set of each monitoring point according to the number of the monitoring point after voltage sag is monitored, taking an intersection of the observable line sets among the monitoring points, and determining a first fault line set corresponding to the observable line of each monitoring point;
for each monitoring point, judging whether a voltage sag source is positioned at the upstream or the downstream of the monitoring point according to the reactive power change condition of the monitoring point, extracting corresponding upstream lines or downstream lines of the voltage sag source on a power grid line according to the judgment result of the position of the voltage sag source, taking intersection of fault lines of the monitoring points, and determining a second fault line set corresponding to the voltage sag source;
taking an intersection of the first fault line set and the second fault line set, and determining a third fault line set corresponding to the voltage sag source;
and determining a monitoring point number corresponding to the voltage sag source according to the third fault line set, and determining the position of the voltage sag source by adopting a sparrow search algorithm by taking the minimum sum of the error values of the theoretical calculated value of the voltage after the fault corresponding to the monitoring point number and the actual observed value as a target.
2. The method according to claim 1, wherein the step of constructing an impedance matrix of a plurality of network nodes on the grid line according to the electrical parameters of the grid and setting a plurality of monitoring points on the grid line based on the impedance matrix comprises:
establishing a functional relation between the fault distance between the fault point on the power grid line and the monitoring point on the power grid line and the sag amplitude of the monitoring point, wherein the process is as follows:
if the system has a three-phase symmetric short-circuit fault at node n, the voltage at node m may be given by the fault occurring at node n:
wherein,
representing the voltage before failure, Δ V, of node m mn Representing the amount of change in the voltage at node m due to a fault at node n;
the condition that the three-phase voltage at the node m is reduced due to the fault of the node n is as follows:
wherein, V sag (m, n) represents the voltage sag of node m at the time of node failure,
representing the voltage before failure of node n, Z mn Representing the mutual impedance between node m and node n, Z nn Representing the self-impedance of node n.
3. The method of claim 2, comprising:
when a fault point on the grid line is located at a point p between the node m and the node n, the voltage sag of the node k caused by the fault point p on the grid is calculated as follows:
the new impedance generated by fault location p is calculated from node k,
Z kp ＝(1-λ)×Z km +λ×Z kn
Z pp ＝(1-λ) 2 ×Z mm +λ 2 ×Z nn +2λ(1-λ)×Z mn +λ(1-λ)×z mn
wherein L is mn Representing the distance between two associated nodes m and n in the network;
L mp represents the distance between node m and the point of failure p;
Z kp represents the transmission impedance between node k and fault point p;
Z pp represents the self-impedance of the fault point p;
Z mn representing the mutual impedance between node m and node n.
The voltage before p-point failure is
The relationship between the voltage at the node k and the fault distance can be solved by the simultaneous expression.
4. The method according to claim 1, wherein the step of constructing an impedance matrix of a plurality of network nodes on the grid line according to the electrical parameters of the grid and setting a plurality of monitoring points on the grid line based on the impedance matrix comprises:
the matrix formed by the monitoring points is as follows:
wherein, the total number of nodes on the power grid line is represented by N, the total number of fault points of the power grid is represented by P, and the voltage of the node i when the fault point j has a fault is represented by U ij Indicates when U is ij Below a set threshold U t Time M (i,j) 1 indicates that a voltage sag has occurred at node i.
5. The method according to claim 1, wherein for each monitoring point, determining whether the voltage sag source is located upstream or downstream of the monitoring point according to the reactive change condition of the monitoring point, extracting corresponding upstream or downstream lines of the voltage sag source on the power grid line according to the determination result of the voltage sag source position, and determining a second fault line set corresponding to the voltage sag source by taking an intersection of fault lines of each monitoring point, includes:
extracting upstream and downstream power grid lines corresponding to the monitoring points according to the electrical parameters corresponding to each monitoring point on the power grid lines;
for theMonitoring point m, with its upstream line sequence J Vup-m And the downstream line sequence is J Vdown-m Before the temporary drop of the monitoring point m occurs, the idle work is Q m The idle work in the temporary reduction process is Q fm According to the reactive change condition of the monitoring point m, the voltage sag source is judged to be positioned at the upstream or the downstream of the monitoring point m,
and for each monitoring point, extracting corresponding upstream or downstream lines according to the judgment result of the voltage sag source position, and determining a second fault line set corresponding to the voltage sag source by taking intersection of possible lines of each monitoring point.
6. The method for positioning the voltage sag source according to claim 1, wherein the determining, according to the third faulty line set, a monitoring point number corresponding to the voltage sag source, and determining, by using a sparrow search algorithm, a position of the voltage sag source with a target of a minimum sum of error values between theoretical calculated values of post-fault voltages and actual observed values corresponding to the monitoring point number, comprises:
after the monitoring point number corresponding to the voltage sag source is determined according to the third fault line set, the step of determining the position of the voltage sag source by adopting a sparrow search algorithm comprises the following steps:
firstly, the optimization variables are set as follows, namely a fault occurrence branch l (discrete type), a relative distance lambda (continuous type) between a fault point and a first section of the fault branch and a transition resistance R f (continuous type) as an optimization variable;
secondly, the sum of the error value of the theoretical calculation value of the voltage after the fault at the monitoring point and the actual observation value is minimum as a target, specifically
Wherein, Δ u m (l,λ,R f ) The relative distance between the upper part of the fault branch and the head end of the fault branch is lambda, and the transition resistance is R f The voltage error value at the mth monitoring point; m is the number of monitoring points.
7. A voltage sag source positioning device, comprising:
the power grid network construction module is used for constructing impedance matrixes of a plurality of network nodes on a power grid line according to electrical parameters of a power grid, and setting a plurality of monitoring points on the power grid line based on the impedance matrixes;
the first fault line set determining module is used for respectively extracting observable line sets of the monitoring points according to the monitoring point numbers after the voltage sag is monitored for the monitoring points, taking intersection sets of the observable line sets among the monitoring points, and determining a first fault line set corresponding to the observable line sets of the monitoring points;
the second fault line set determining module is used for judging whether a voltage sag source is positioned at the upstream or the downstream of each monitoring point according to the reactive power change condition of the monitoring point, extracting the corresponding upstream line or the downstream line of the voltage sag source on the power grid line according to the judgment result of the position of the voltage sag source, taking the intersection of the fault lines of each monitoring point and determining a second fault line set corresponding to the voltage sag source;
a third faulty line set determining module, configured to take an intersection of the first faulty line set and the second faulty line set, and determine a third faulty line set corresponding to the voltage sag source;
and the voltage sag source determining module is used for determining a monitoring point number corresponding to the voltage sag source according to the third fault line set, and determining the position of the voltage sag source by adopting a sparrow searching algorithm by taking the minimum sum of the error value of the theoretical calculated value of the voltage after the fault corresponding to the monitoring point number and the actual observed value as a target.
8. An electronic device comprising a processor, a memory, and a program or instructions stored on the memory and executable on the processor, the program or instructions when executed by the processor implementing the steps of the method of any of claims 1-6.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115469192A (en) * | 2022-11-02 | 2022-12-13 | 国网信息通信产业集团有限公司 | Voltage sag source positioning method and positioning system |
| CN117439068A (en) * | 2023-10-26 | 2024-01-23 | 国网宁夏电力有限公司中卫供电公司 | Voltage sag estimation method, medium and system in large-scale power grid |
| CN117591812A (en) * | 2024-01-18 | 2024-02-23 | 山东黄海智能装备有限公司 | Intelligent electronic stethoscope electric signal noise reduction processing optimization method |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115469192A (en) * | 2022-11-02 | 2022-12-13 | 国网信息通信产业集团有限公司 | Voltage sag source positioning method and positioning system |
| CN117439068A (en) * | 2023-10-26 | 2024-01-23 | 国网宁夏电力有限公司中卫供电公司 | Voltage sag estimation method, medium and system in large-scale power grid |
| CN117439068B (en) * | 2023-10-26 | 2024-05-14 | 国网宁夏电力有限公司中卫供电公司 | Voltage sag estimation method, medium and system in large-scale power grid |
| CN117591812A (en) * | 2024-01-18 | 2024-02-23 | 山东黄海智能装备有限公司 | Intelligent electronic stethoscope electric signal noise reduction processing optimization method |
| CN117591812B (en) * | 2024-01-18 | 2024-04-26 | 中国人民解放军总医院第二医学中心 | Intelligent electronic stethoscope electric signal noise reduction processing optimization method |
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