CN110658419B - Micro-grid fault positioning method based on incomplete information - Google Patents
Micro-grid fault positioning method based on incomplete information Download PDFInfo
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Abstract
A micro-grid fault positioning method based on incomplete information relates to the field of micro-grid control, in particular to a fault positioning method on a micro-grid bus. The method for positioning the fault of the micro-grid bus comprises the following steps that N nodes are arranged on the micro-grid bus, and data acquisition equipment is arranged on m nodes: step A, information acquisition; step B, generating a calculation formula when a fault occurs; step C, solving the calculation formula generated in the step B; d, positioning a fault position according to the result of the step C; by adopting the method provided by the invention, the fault position on the bus of the microgrid can be positioned according to less information acquisition equipment, and the economic cost is saved.
Description
Technical Field
The invention relates to the field of microgrid control, in particular to a fault positioning method on a microgrid bus.
Background
The micro-grid is a small-sized power generation and distribution system which is formed by collecting distributed generation units (DGs), energy storage devices, energy conversion devices and phase loads, monitoring devices and protection devices. The system is an autonomous system capable of realizing self control, protection and management, and can be operated in a grid-connected mode with a large power grid or independently. Generally, a small-sized microgrid system comprises a plurality of distributed power supplies, energy storage devices and a large number of loads, and the connection mode of the plurality of devices makes wiring of the microgrid system complicated and branch lines numerous.
In a normal state, the micro-grid is connected to a power distribution network through a static switch and is used as a controllable unit to run in a grid-connected mode; and the isolated power grid can also be used as an autonomous system island operation (island mode) by being isolated from the power distribution network, so that the influence of the power grid fault on the normal operation of the load in the microgrid is avoided.
Fault location technology is one of the key technologies in power systems, and conventional fault location methods include impedance method, traveling wave method, and fault location algorithm based on artificial intelligence, etc. In conventional fault location methods, it is generally assumed that the two ends of the fault line include at least one end voltage or current measurement. In transmission networks or medium-high voltage distribution networks, this condition is generally met, but is difficult to achieve in micro-grids.
In addition, the effective grounding mode of the micro-grid is different from that of the power distribution network, and the neutral point of the micro-grid line mostly adopts a non-effective grounding system with the neutral point not grounded or grounded through an arc suppression coil, so that the fault positioning method applied to the power distribution network is not necessarily applied to the micro-grid.
The chinese patent application CN 102866315 a discloses a symmetric fault analysis method for a power distribution network with an inverter-type distributed power supply, which treats distributed power stations as a whole power supply without considering the internal structure of the microgrid.
Chinese patent application CN 109142986 a discloses a method for locating a fault on an ac distribution line, which does not consider the case of distributed power sources, and in which the algorithm always has two solutions, and if the nodes represented by the two solutions are not adjacent, the fault point cannot be located accurately.
Disclosure of Invention
In view of the above situation, the present invention provides a method for positioning a fault on a bus by only partial measurement, which is applicable to a microgrid.
In order to achieve the purpose, the invention adopts the technical scheme that:
the microgrid fault positioning method based on incomplete information is used for positioning fault positions on a microgrid bus, the microgrid bus is provided with N nodes, and data acquisition equipment is arranged on the m nodes.
Step A, information acquisition;
step B, generating a calculation formula when a fault occurs;
step C, solving the calculation formula generated in the step B;
and D, positioning the fault position according to the result of the step C.
The key point is that:
m＞N-m。
in step B, a calculation formula is generated according to the following formula.
For a three-phase power network with N nodes, the network equation can be expressed as:
yu equation 1
Wherein Y ∈ RN×NThe node admittance matrix, u the node voltage vector, and i the node current injection vector.
When the micro-grid system fails, the variable quantities U and I of the voltage and the injection current meet a network equation:
YU equation 2
In a microgrid with N nodes, the number of nodes that can collect data is m, the number of nodes that cannot collect data is N-m, and the deformation of formula 2 is:
from the gaussian elimination one can get:
note the book
x＝In，y＝Im-YredUmThen the above equation can be simplified as:
equation 5 where y is ax
In formula 5, y is information obtained by a node having data acquisition equipment, and the order is m, x is an unknown quantity, and the order is n.
In step C, a sparse solution x is iteratively constructed, and the specific algorithm is as follows.
Inputting: A. y, U, output: and x and A are m × n, namely, an admittance parameter matrix of m rows and n columns.
C11) Initializing a set of tags
Residual vector r0Y, the number of iteration steps k is 1,
representing an empty set;
C12) sum residual vector r in matrix Ak-1The strongest correlation column jk∈argmax|＜rk-1，Ωk-1＞|，Ωk＝Ωk-1∪jk；
C13) Estimating minimization problem
C14) Updating residual errors
C15) Let k be k +1, repeat steps C12) through C14) until the iteration termination criterion is met.
The iteration termination criterion is as follows: the residual approaches 0 stop or stops when none of the columns in a is significantly correlated with the residual.
In step D, finding out the fault position according to the obtained solution:
if all 0 solutions are obtained, finding out the fault position according to the acquired information;
if 1 non-0 solution is obtained, the fault position is positioned at two sides of the node represented by the non-0 solution, and the fault position is found according to the acquired information;
if two non-0 solutions are obtained, the fault location is between the nodes represented by the two non-zero solutions.
In the first case: and obtaining a full 0 solution, which indicates that the fault occurs between two nodes capable of collecting information, and at the moment, the traditional fault positioning method can be used for positioning, such as: a voltage and current abrupt change threshold value judgment method, an impedance positioning method, a traveling wave positioning method and the like.
In the second case: and obtaining 1 non-0 solution, which indicates that the fault occurs between a node capable of collecting information and a node incapable of collecting information, comparing the voltage and current information of nodes (both of which can collect information) at two sides of a node represented by a non-zero solution (represented as 1), wherein the node with a larger mutation amount (represented as 2) is the node closest to the fault position, and the fault position is between the nodes 1 and 2.
Further:
in the step C, firstly, the operation state of the microgrid is obtained, and if the microgrid operates in an island mode, a sparse solution x is iteratively constructed; otherwise, the calculation is solved by the following steps.
Inputting: A. y, U, n, output: and x and A are admittance parameter matrixes of m and n.
C21) Judging the fault range: if not on the DG side, satisfy
The output fault is not within the micro-grid range, and the operation is terminated, otherwise, the operation enters C22); in the above formula, Y is a transposed matrix of Y.
C22) And setting the iteration step number k as 1.
C23)
If it is
Then x is output and terminated, otherwise C24 is entered).
C24) If it is not
K is set to k +1, C25 is entered), otherwise, the output calculation fails, and the process is terminated.
C25) If it is not
Go to C23), otherwise the output calculation fails, and terminates.
Wherein x isiRepresenting i quantities, x, in the matrix of xi (0)Represents xiThe first calculated value of (a).
The value range of i is 1 to n, and the value range of j is 1 to m; and epsilon is the fault positioning precision, and the value of epsilon is 0.001.
Furthermore, a time service module, such as a GPS (global positioning system) and a Beidou terminal, is arranged in the data acquisition equipment, and in the step A, the acquired data carries time information; in step C, the data of the same time slice is used for calculation.
By adopting the method provided by the invention, the voltage and current information is used at the same time, and the reliability is higher than that of single voltage or current; the algorithm is simple and easy to realize; based on a known micro-grid topological structure, according to less information acquisition equipment, fault information can be acquired from an existing protection device, and the fault position on a micro-grid bus can be positioned without adding other equipment, so that the economic cost is saved; aiming at the state (grid connection or island) of the micro-grid, different judgment modes are adopted, so that the fault positioning is more accurate and reliable; the data of the uniform time section is used for processing, so that the consistency of the data in time is ensured, and the influence caused by simultaneous processing of the sampled data of different events is avoided; the method can realize higher fault positioning precision, shorten the time from fault occurrence to fault processing and reduce economic loss caused by faults to the micro-grid system.
Drawings
Figure 1 is a topological diagram of a microgrid,
figure 2 is an equivalent fault current using current injected across the node,
figure 3 is a current profile under fault current injection,
figure 4 is a current distribution under the injected current at node I, J,
figure 5 is a trend graph of residual values at the end of an iteration,
fig. 6 is a current waveform diagram of node 17.
Detailed Description
The present invention will be further described with reference to the accompanying drawings, but the embodiments of the present invention are not limited thereto.
The following embodiment shows the case where the fault location is between two nodes where information cannot be collected, that is, the case where the calculation formula has two non-0 solutions.
In this embodiment, there are N nodes on the microgrid bus, and nodes connected to a distributed generation unit (DG), an electric device, and the like, as shown in fig. 1 as 1, 2, 3, 16, 17, and the like, are nodes. There are data acquisition devices on m of the nodes, and > N-m. In fig. 1, the data acquisition device is not shown.
In fig. 1, an islanding detection device is used to detect the operating state of a microgrid.
For a three-phase power network with N nodes, the network equation can be expressed as:
yu equation 1
Wherein Y ∈ RN×NThe node admittance matrix, u the node voltage vector, and i the node current injection vector.
When the micro-grid system fails, the variable quantities U and I of the voltage and the injected current also meet the constraint of a network equation:
When the microgrid system fails at point f on a line between nodes I, J, the change I of the fault currentfCan be equivalent to injecting virtual abrupt current I at the node I and the node JiAnd Ij. Wherein Z isifAnd ZjfLine impedance, Z, to both side nodes I, J at the fault pointithAnd ZjthRespectively, the equivalent thevenin impedances from the nodes on both sides of the fault point to the adjacent nodes, as shown in fig. 2.
The virtual abrupt current injected at node I, J is derived below.
The current profile under fault current injection of fig. 2 is shown in fig. 3 and may be equivalent to the current profile under injected current at node I, J shown in fig. 4.
To ensure equivalent correctness, the current I in both cases1、I2Should be equal, the following equations may be listed:
I1＝Ii-I0
I2＝Ij+I0
I0(zif+zjf)＝I1zith-I2zjth
simultaneous obtaining of the above 5 formulae:
the impedance of the transmission line is uniform, zifProportional to the distance x of f from node Ii，zjfDistance x proportional to f and node JjThen, there are:
the above description shows that if the variation I of the injection current can be solved, the fault line can be determined according to the node number I, J of the non-zero element, and further, the virtual equivalent injection current I can be solvedi、IjThe position of the fault can be determined without being influenced by the fault transition resistance and the equivalent impedance of an external system.
The foregoing is the principle upon which the present invention is based.
And step A, information acquisition.
In a microgrid with N nodes, voltage and current data of m nodes are acquired through a sampling device, a time window is added to acquired information through a satellite time setting function, and the other nodes have N-m nodes and are not acquired.
And step B, generating a calculation formula when a fault occurs.
Acquiring a topological structure and online parameters of the microgrid to form a node admittance matrix, so that a network equation can be obtained as follows:
from the gaussian elimination one can get:
note the book
x＝In，y＝Im-YredUmThen the above equation can be simplified as:
equation 5 where y is ax
In formula 5, y is information obtained by a node having data acquisition equipment, and the order is m, x is an unknown quantity, and the order is n;
at this time, if there are more observed nodes than there are no observed nodes, i.e., m > n, the equation is unique in solution; if the number of nodes without observation is larger than that of nodes with observation, namely m < n, the equation is not definite solution, and infinite solutions can be obtained.
However, for faults, the solution of the equation is of a special structure, x ═ InThe current injection increment of the node is only provided with two nonzero elements, and a power transmission line is arranged between the nodes corresponding to the two numbered elements. For such an equation with a special structure, a compressed sensing algorithm can be used for solving.
It is noted that the quantities in the equations are complex numbers, and expanding them in real and imaginary parts yields 2n equations for 2n unknowns.
The analysis shows that for a certain node, the measurement of the whole network and the communication with all nodes are not required, and the fault information of the whole network can be obtained only by the local information (the local information comprises the topological graph of the micro-grid structure, the voltage and current information of the nodes capable of acquiring data, the equivalent impedance between each node (all the nodes capable of acquiring information + the nodes incapable of acquiring information)) and the information of a plurality of nodes nearby and combining the known topological graph of the micro-grid structure.
And C, solving the calculation formula generated in the step B.
In the solving process, the voltage and current data at the same moment are a group, and the data of the section at the same time are used for calculation, so that misjudgment caused by using wrong data in the subsequent process is avoided.
When a fault occurs inside the microgrid, the following conditions are met:
1) with 4 or 8 or 12 non-zero elements (single phase, two phase, three phase depending on the type of fault);
2) the real part and the imaginary part corresponding to a certain current are necessarily 0 or non-zero at the same time (ignoring the case that the solution is just real or pure imaginary);
3) there must be branches between the solved nodes I, J, in other words, nodes that are not directly connected do not simultaneously become non-zero elements of the sparse solution.
Aiming at the characteristics, the 0-norm greedy algorithm for solving the problem of sparse fault information in the off-network state is improved, only the legal column vector group is searched after improvement, and the timeliness of the algorithm is improved.
The basic idea of the algorithm is to consider iteratively constructing a sparse solution x. The observation vectors are sparsely approximated using only a linear combination of a few column vectors of the dictionary matrix a, wherein the set of selected column vectors in the dictionary matrix is established column by column, and in each iteration step, the column vector of the dictionary matrix most similar to the current residual is selected as the new column.
In the present application, the dictionary matrix a is an admittance parameter matrix of m × n.
The specific algorithm is as follows:
inputting: A. y, output: x, the parameter of A is represented by YmnAnd (4) forming.
C11) Initializing a set of tags
Residual vector r0Y, the number of iteration steps k is 1,
indicating an empty set.
C12) Sum residual vector r in matrix Ak-1The strongest correlation column jk∈argmax|＜rk-1，Ωk-1＞|，Ωk＝Ωk-1∪jk。
argmax is a function, and argmax is opposite to argmin and is respectively the maximum value and the minimum value of the solution of the function; the function y (f) (x), x0 (argmax (f (x)) means that the parameter x0 satisfies the maximum value of f (x0) being f (x); in other words, argmax (f (x)) is the variable x corresponding to the maximum value of f (x). arg is argument, which is meant herein as "argument".
Example (c): f (x) ═ x +5, where x ═ 3, -2, -1, 0, then argmax (f (x) ═ 0, i.e., x ═ 0, f (x) has a maximum value f (x) ═ 5, argmin is the opposite, and argmin (f (x) ═ -3, i.e., f (x) when x ═ 3 has a minimum value f (x) ═ 2.
The formula | < |, which represents the vector inner product, and the whole is expressed as the absolute value of the vector inner product.
In the step, each column in the matrix A is subjected to correlation analysis with the residual vector once, and finally the column jk with the highest correlation with the residual vector is obtained.
C13) Estimating minimization problem
C14) Updating residual errors
In C13) and C14), the two formulas look the same, but the x used is different, and the end purpose is different: step C13) is aimed at solving for the minimum solution in absolute value, which is a vector matrix with respect to x, where the final solution is generated. Step C14) is aimed at assigning this vector to the residual rKAnd the calculation is used for the next step.
C15) Let k be k +1, repeat steps C12) through C14) until the iteration termination criterion is satisfied;
the iteration termination criterion is as follows: the residual either comes to a stop at 0 or stops when no column in dictionary a is clearly correlated with the residual.
The trend of the values of the residuals at the end of the iteration is shown in fig. 5.
The algorithm and the check formula involved in the present application can be expressed by using the trend graph of which all the trend graph is close to zero. In practice, the application can be terminated only by determining the trend.
Description on some representation methods in the matrix: in this specification, Y(i)Representing the ith column of the Y matrix, not the i-th power of Y, Y(i)Represents the ith row of the Y matrix (in matrix operations, brackets are often omitted for ease of writing).
Or YijEach representing that particular value in column i and row j of matrix Y.
Example 1.
In fig. 1, the microgrid includes 17 nodes in total, and it is assumed that voltage and current information of 10 of the nodes can be acquired, and the node: 2. 3, 5, 7, 8, 9 and 11 voltage and current information cannot be collected (m is 10, and n is 7). And single-phase earth faults occur between the nodes 2 and 3 in the island operation. The operating state is obtained by an island detection device.
When a fault occurs, the current waveform at node 17 is as shown in fig. 6.
And acquiring voltage and current information of the collectable nodes.
In the formula y-ax, the formula,
the data carries time information according to the data, and the data of the same time section.
Where the subscripts of m and n represent the specific nodes of the corresponding microgrid. The physical meaning of each number is shown as the first column of the same row: admittance between node 1 and node 2; as indicated by the fifth row and the third column: admittance between node 5 and node 12, and so on. When two nodes at corresponding positions in the A matrix are not two adjacent nodes, the value of the two nodes is 0, and thus the sparse matrix A is formed.
The calculation output is:
the meaning of the results represents: and (3) non-collected information nodes: 2. 3, 5, 7, 8, 9, 11, and if the first node and the second node among the nodes having n equal to 7 are represented by two non-zero solutions, a failure occurs between the nodes corresponding to 2 and 3 actually.
After the above solution is completed, the results are verified using the following method:
xtest (experiment)＝arg minJ(x)
In the above formula, λ ∈ (0, + ∞), if λ is within a certain range, xTest (experiment)The error in comparison with x approaches 0, the calculation is correct.
The concrete implementation is as follows:
theoretically, λ should be traversed, and the value of λ is substituted into the above formula for judgment, but traversal cannot be realized.
The range of λ can be determined by:
by calculating the limit, the values of 0 and λ at infinity are obtained, and the range is narrowed between the obtained values, such as [1,10000], [100,15000], and the like. If the trend of 0 still does not exist after 100 times of selection, the calculation is considered to be wrong, and the fault information needs to be checked and recalculated.
The following is the verification process under normal circumstances.
Firstly, two values of which the phase difference is large are taken as lambda, such as lambda 1 and lambda 2 with the phase difference of 1000, and two results x are calculatedTest (experiment)-x, denoted R1 and R2, respectively, if R2>R1, if the calculated result is R3, if the calculated result is R1, taking the lambda 3 as (lambda 1+ lambda 2)/2<R3<R2, if the calculated result is R4, if the calculated result is R1, taking the lambda 4 as (lambda 3+ lambda 1)/2<R4<R3, and so on, if it is always this trend, then x is consideredTest (experiment)The error approaches 0 compared to x.
If R2<R1, if the calculated result is R3, if the calculated result is R2, taking the lambda 3 as (lambda 1+ lambda 2)/2<R3<R1, if the calculated result is R4, if the calculated result is R2, taking the lambda 4 as (lambda 3+ lambda 2)/2<R4<R3, and so on, if it is always this trend, then x is consideredTest (experiment)The error approaches 0 compared to x.
In the above judgment, comparison is performed by absolute value.
In example 1, the correlation data were calculated and the results were as follows:
xtest (experiment)The error of contrast with x approaches to 0, i.e. the calculation result is correct.
Due to the particularity of the microgrid structure, under the same condition, the fault current in a grid-connected mode is greatly different from the fault current in an off-grid (island) mode, the fault current is relatively large in a grid-connected state, the current is small when a fault occurs inside the microgrid in the off-grid state, and the operation state of the microgrid is acquired through a central controller.
The algorithm can effectively judge the fault position of the bus in the off-grid state, but the algorithm is not reliable in the grid-connected state.
When a fault occurs, firstly, the state of the microgrid is detected through an island detection device, if the microgrid is in a grid-connected state and the outside of the microgrid has a fault, the nodes inside the microgrid can also generate fault current, so that when the fault is positioned, firstly, whether the fault is inside or outside the microgrid is distinguished, and then, the fault is positioned.
The method is realized as follows:
example 2.
In fig. 1, the microgrid includes 17 nodes in total, and it is assumed that voltage and current information of 10 of the nodes can be acquired, and the node: 2. 3, 5, 7, 8, 9 and 11 voltage and current information cannot be collected (m is 10, and n is 7). And single-phase earth faults occur between the nodes 2 and 3 during grid-connected operation.
Inputting: a is as above, Y is the transpose of Y above; u is the voltage increment corresponding to Y; and n is 7, namely, 7 nodes which can not acquire information exist.
Transposing the matrix by interchanging the rows and columns of the matrix, e.g. by inverting the rows and columns
After the rotation, the method comprises the following steps:
firstly, judging a fault range: C21) judging the fault range: if not on the DG side, satisfy
The output fault is not within the microgrid range.
The total number of 10 nodes of the information can be collected, wherein 15, 16 and 17 are power supply nodes. When a fault occurs, the calculation error for the power supply node is large, and no calculation process is performed, or only calculation is performed, and no judgment is performed.
If the data calculations of nodes 1, 4, 6, 10, 12, 13, 14 all satisfy:
and if the output fault is not in the range of the micro-grid, exiting, otherwise, carrying out the following calculation.
C22) And setting the iteration step number k as 1.
C23) For each k, calculating a value, wherein the value range of i is 1 to n, and the value range of j is 1 to m:
and (3) judging: if it is
Then x is output and terminated, otherwise C24 is entered).
C24) Judging whether the iteration times are reached: if it is not
K is set to k +1, C25 is entered, otherwise, the output calculation fails, and the operation is terminated;
C25) if it is not
Go to C23), otherwise the output calculation fails, and terminates.
Wherein x isiRepresenting i quantities, x, in the matrix of xi (0)Represents xiThe first calculated value of (a).
And epsilon is the fault positioning precision, and the value of epsilon is 0.001.
The calculation output is:
the meaning of the results represents: and (3) non-collected information nodes: 2. 3, 5, 7, 8, 9, 11, and if the first node and the second node among the nodes having n equal to 7 are represented by two non-zero solutions, a failure occurs between the nodes corresponding to 2 and 3 actually.
And (3) verification: in the case of the example 2, the following examples were conducted,
xtest (experiment)The error of contrast with x approaches to 0, i.e. the calculation result is correct.
And D, the fault point is between two nodes represented by non-zero solutions, namely between the nodes 2 and 3 in the two embodiments.
In step D, a fault location between I, J nodes is obtained, and a virtual equivalent injection current of the two nodes is obtained. The impedance of the transmission line is uniform, zifDistance x proportional to f and ii，zjfDistance x proportional to f and jjAssuming that the line length between the two nodes is L, the distance from the fault point to the node I, J is xi、xjAccording to the following formula:
xi+xj＝L
in embodiment 1, the distance between the nodes 2 and 3 is divided into 7 parts, the distance between the fault point and the node 2 is 1 part, and the distance between the fault point and the node 3 is 6 parts. And according to the distance L between the two nodes, the line length from the fault point to the two nodes can be obtained.
Claims (5)
1. The microgrid fault positioning method based on incomplete information is used for positioning fault positions on a microgrid bus, the microgrid bus is provided with N nodes, and data acquisition equipment is arranged on the m nodes, and the fault positioning method comprises the following steps:
step A, information acquisition;
step B, generating a calculation formula when a fault occurs;
step C, solving the calculation formula generated in the step B;
d, positioning a fault position according to the result of the step C;
the method is characterized in that:
m>N―m；
in step B, a calculation formula is generated according to the following formula:
for a three-phase power network with N nodes, the network equation can be expressed as:
i = Yu equation 1
Wherein Y ∈ RN×NA node admittance matrix, u a node voltage vector, i a node current injection vector,
when the micro-grid system fails, the variable quantities U and I of the voltage and the injection current meet a network equation:
i = Y U formula 2
In a microgrid with N nodes, the number of nodes that can acquire data is m, the number of nodes that cannot acquire data is N = N-m, and the transformation of formula 2 is:
From the gaussian elimination one can get:
Note the book
Then the above equation can be simplified as:
y = ax equation 5
In formula 5, y is information obtained by a node having data acquisition equipment, and the order is m, x is an unknown quantity, and the order is n;
in the step C, firstly, the operation state of the microgrid is obtained, if the microgrid operates in an island mode, a sparse solution x is iteratively constructed, and the specific algorithm is as follows:
inputting: A. y, U, output: x, A is admittance parameter matrix of m x n,
C11) initializing a set of tags
Residual vector r0= y, number of iteration steps k =1,
representing an empty set;
C12) sum residual vector r in matrix Ak-1Strongest correlation column
C13) Estimating minimization problem
；
C14) Updating residual errors
；
C15) Let k = k +1, repeat steps C12) to C14) until the iteration termination criterion is satisfied;
the iteration termination criterion is as follows: the residual approaches 0 to stop or stops when none of the columns in a is significantly correlated with the residual;
in step D, finding out the fault position according to the obtained solution:
if all 0 solutions are obtained, finding out the fault position according to the acquired information;
if 1 non-0 solution is obtained, the fault position is positioned at two sides of the node represented by the non-0 solution, and the fault position is found according to the acquired information;
if two non-0 solutions are obtained, the fault location is between the nodes represented by the two non-zero solutions.
2. The method of claim 1, wherein:
in the step C, firstly, the operation state of the microgrid is obtained, and if the microgrid operates in an island mode, a sparse solution x is iteratively constructed; otherwise, solving the calculation formula by:
inputting: A. y, U, n, output: x, A is admittance parameter matrix of m x n,
C21) judging the fault range: if not on the DG side, satisfy
If the output fault is not in the range of the microgrid, the operation is terminated, otherwise, the operation enters C22); in the above formula, Y is a transposed matrix of Y;
C22) setting iteration step number k = 1;
C23）
if it is
Then x is output and terminated, otherwise go to C24);
C24) if it is not
Setting k = k +1, entering C25), otherwise, outputting a failure calculation, and terminating;
C25) if it is not
Go to C23), otherwise output calculation fails, terminate;
wherein the content of the first and second substances,x i representing the ith quantity in the x-matrix being sought,x i （0） representsx i The primary calculated value of (a);
the value range of i is 1 to n, and the value range of j is 1 to m;εin order to achieve the accuracy of the fault location,εthe value is 0.001.
3. The method according to claim 1 or 2, characterized in that:
in the step C, after the solution is completed, the method further comprises the following verification steps:
in the above formula, if λ ∈ (0, + ∞) is within a certain range,x test (experiment)The error in comparison with x approaches 0, the calculation is correct.
4. The method according to claim 1 or 2, characterized in that: in the step A, the acquired data carries time information; in step C, the data of the same time slice is used for calculation.
5. The method of claim 1, wherein:
in step D, it is obtained that the fault location is between I, J two nodes, and assuming that the line length between the two nodes is L, the distance between the fault point and the node I, J is xi、xjAccording to the following formula:
xi+xj=L
Ii、Ijthe line length from the fault point to the two nodes can be obtained for the virtual equivalent injection current of the two nodes.
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