CN111650473B

CN111650473B - Fault indicator-based power distribution network fault section positioning method

Info

Publication number: CN111650473B
Application number: CN202010516847.0A
Authority: CN
Inventors: 王占山; 万富康; 刘明凯; 杨东升
Original assignee: Northeastern University China
Current assignee: Northeastern University China
Priority date: 2020-06-09
Filing date: 2020-06-09
Publication date: 2021-06-08
Anticipated expiration: 2040-06-09
Also published as: CN111650473A

Abstract

The invention provides a power distribution network fault section positioning method based on a fault indicator, and relates to the technical field of power distribution network fault positioning. The method comprises the following steps: establishing an incidence matrix A with a virtual feeder, establishing an adjacency list reflecting the structural state of the power distribution network and obtaining an accurate fault indicator state information matrix B by applying an iterative method for correction; the fault indicator state information matrix B and the incidence matrix A and the feeder line state matrix C have the following relations: b ═ AC. The problem of a power distribution network containing a distributed power supply can be solved by establishing an incidence matrix A with a virtual feeder; because the invention has strong dependency on the accuracy of the state information of the fault indicator, the adjacency list is adopted to reflect the structure of the power distribution network, and the iterative method is used to correct the state information of the fault indicator, thereby improving the accuracy of positioning. The effectiveness of the invention is verified by simulation examples.

Description

Fault indicator-based power distribution network fault section positioning method

Technical Field

The invention relates to the technical field of power distribution network fault location, in particular to a power distribution network fault section location method based on a fault indicator.

Background

At present, as people continuously improve the reliability of power utilization in daily production and life, the topic of ensuring the reliability of power supply of a power distribution network becomes popular. Due to the continuous expansion of the scale of the power distribution network, the sensitivity of the power distribution network to faults is higher and higher. According to the statistical data of the faults of the customers, about 80 percent of the faults occur in the power distribution network, so that the rapid and accurate positioning of the faults in the power distribution network plays a significant role in improving the reliability of power supply.

Many excellent scholars have proposed various fault location methods for improving the power supply reliability of the power distribution network, and the methods can be classified into an impedance method, a traveling wave method and a wide area communication method according to the principle. The impedance method can accurately calculate the fault distance and has low cost. However, because the distribution network has a plurality of branches, a plurality of 'false fault points' can appear when the fault is positioned by using an impedance method, and the accuracy of fault positioning is reduced. In general, it is more suitable for fault location on long-distance transmission lines. The traveling wave method has been widely applied to power transmission systems, and many improved traveling wave methods are also applied to power distribution networks, however, when a high-impedance fault occurs, the traveling wave amplitude generated by the fault is severely attenuated, so that the positioning efficiency of the method is poor. Moreover, the length of a feeder line of the power distribution network is much smaller than that of the power transmission network, and the traveling wave propagation speed is high, so that the fault location distance has a large error.

With the gradual application of Distribution Automation (Distribution Automation DA) to power Distribution networks, a wide area communication method has been developed, which locates a fault section by performing multipoint measurement on the power Distribution network, and mainly includes a matrix algorithm and an optimization algorithm. The matrix algorithm needs to search all elements in the matrix in a traversing way, so that the calculation amount is large, the dependence on the accuracy of the measurement information is strong, and the anti-jamming capability is poor; the optimization algorithm utilizes the structure of the power distribution network and fault information to form an evaluation function, and various optimization methods (particle swarm optimization, ant colony optimization and the like) are used for positioning fault sections. Due to the fact that the number of branches of the power distribution network is large, the number of solving variables is large, the result that the positioning speed is slow is caused, and the optimization method has the defect that the optimization method is prone to falling into local optimization, and therefore positioning failure is caused.

Disclosure of Invention

In view of the continuous promotion of distribution automation, the invention provides a power distribution network fault section positioning method based on a fault indicator, and the fault section is quickly and accurately positioned by means of current information provided by a communication measuring device in a power distribution network.

The technical scheme adopted by the invention is as follows:

a power distribution network fault section positioning method based on a fault indicator comprises the following steps:

step 1: fault indicators are installed at a circuit breaker, an isolating switch and a fuse in a power distribution network, a distributed power supply is installed at the tail end of a branch of the power distribution network, and an incidence matrix A with a virtual feeder line is established;

the step 1 specifically comprises the following steps:

step 1.1: replacing distributed power sources contained in the radial power distribution network with virtual feeders;

step 1.2: numbering the fault indicator and the feeder line sections, wherein the maximum numbers of the fault indicator and the feeder line sections are respectively set as M and N;

step 1.3: setting the current flowing from the main power supply to each branch circuit to be in a positive direction;

step 1.4: let k ₀1 is used as the initial number of the fault indicator, i is the number of the fault indicator, and j is the number of the feeder line section; the elements in the incidence matrix A are defined as status information of the fault indicator i when the feeder section j fails, i.e. a_ij；

Step 1.5: let i be k₀J is 1, judge a_ijThe value of j is increased from 1 to the maximum value N, and a is determined one by one_ijA value of (d);

step 1.6: let k₀Self-increment by 1, and then return to the step 1.5;

step 1.7: up to k₀Obtaining the maximum value M of the fault indicator number and finishing the step 1.5, and then finishing the program; otherwise, return to step 1.6.

Step 2: establishing an adjacency list reflecting the structural state of the power distribution network;

the adjacent table displays the serial numbers of the fault indicators, the serial numbers of the upstream and downstream fault indicators of each fault indicator and the state information of the fault indicators; the adjacency list specifies that only the indicators adjacent to each other have an upstream-downstream relationship;

the fault indicator uses a bi-directional fault indicator; when the fault indicator detects a fault current in accordance with the set positive direction, the fault indicator lamp is on, indicated by the numeral "1", and when a fault current opposite to the set positive direction is detected or no fault current is detected, the fault indicator lamp is off, indicated by the numeral "0".

And step 3: correcting the state information of the fault indicator by using an iterative method so as to obtain a state information matrix B of the fault indicator;

the step 3 specifically comprises the following steps:

step 3.1: setting M as the number value of no fault indicator at the downstream in the whole adjacency list, wherein M is 1,2, …, M;

step 3.2: determining the state of the fault indicator m;

step 3.3: if FI_mIs the m-th fault indicator, if FI_mThe state of (3) is '0', the upstream fault indicator number of the mth fault indicator is known according to the adjacency list, the number is assigned to m, and the step (3.2) is returned, otherwise, the next step is carried out;

step 3.4: obtaining the upstream indicator number of the mth fault indicator according to the adjacency list, and assigning m to the number;

step 3.5: determining a state of an mth fault indicator;

step 3.6: if the state of the indicator is "0", then the information of the device is lost, and the state of the indicator is modified to "1"; otherwise, the information is not lost;

step 3.7: detecting the value of m, and stopping the program if the value of m is equal to 1; otherwise, return to step 3.4.

And 4, step 4: and the data processing unit solves a matrix C by using a formula B which is AC, wherein C is a feeder line section state matrix, and a positive value in C is a fault section.

The data processing unit collects state information of the fault indicator in a wireless communication mode.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:

the invention provides a power distribution network fault section positioning method based on a fault indicator, which considers the influence of a distributed power supply on the whole power distribution network structure after being put into the power distribution network and is more suitable for the development of the future power distribution network; secondly, the current information provided by the measuring equipment (fault indicator) in the power distribution network is fully utilized. Compared with the traditional optimizing method, the method has the advantage that the positioning speed is obviously improved.

Because the installation environment of the fault indicator is severe, when the fault occurs, the state of the fault indicator is easy to lose, and the fault positioning is not accurate.

In conclusion, the invention greatly improves the positioning speed and the positioning accuracy. From a cost perspective, the fault indicator is lower relative to other measuring devices (feeder termination unit, miniature vector measuring device).

Drawings

FIG. 1 is a main flow chart of a fault indicator-based power distribution network fault section positioning method according to the present invention;

fig. 2 is a T-type coupled node power distribution network including virtual feeder sections according to an embodiment of the present invention;

FIG. 3 shows an embodiment L of the present invention₆A fault indication state indication diagram when a fault occurs;

fig. 4 is a diagram illustrating a power distribution network fault with information loss according to an embodiment of the present invention;

FIG. 5 is a flowchart of a power distribution network fault section location according to an embodiment of the present invention;

FIG. 6 is a diagram of a distribution network of an electric power company of Taiwan in accordance with an embodiment of the present invention;

FIG. 7 is a diagram of a distribution network of an electric company, Taiwan, in which distributed power sources are considered according to an embodiment of the present invention;

fig. 8 is a diagram illustrating a fault status of a distribution network including distributed power sources with information loss according to an embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

A method for positioning a fault section of a power distribution network based on a fault indicator is disclosed, as shown in FIG. 1, and comprises the following steps:

the incidence matrix A with the virtual feeder lines is established by considering the investment of the distributed power supply. The traditional power distribution network is of a single-power radial structure, nodes and feeder line sections are consistent in number, and branches are independent from each other, so that the constructed matrix A is a reversible matrix. After the distributed power supply is put into a power distribution network, the original relation in quantity is broken, and therefore a method for adding virtual feeder line sections is provided to solve the problem;

the step 1 specifically comprises the following steps:

step 1.6: let k₀Self-increment by 1, and then return to the step 1.5;

In this embodiment, for a power distribution network including k DG, M FI, and N feeder sections, the association matrix a is established, where DG is a Distributed power source (Distributed Generation) and FI is a Bi-Directional Fault indicator (Bi-Directional Fault Indicators). From the network structure, M ═ k + N is known, for which purpose k DGs are treated as virtual feeder sections and assigned corresponding numbers.

A power distribution network as shown in fig. 2 is established, which contains 2 DG, 9 FI, 7 feeder sections, for which purpose two DG are considered as two virtual feeder sections, numbered L₈And L₉As shown in fig. 3. Obtaining the matrix shown in the formula (1) according to the construction process of the incidence matrix A. When a fault occurs, the power supply will flow a fault current into the fault point. In the single-power radial distribution network system, a Non-Directional Fault indicator (Non-Directional Fault Indicators) is used because no Fault current flows to a Fault point in any other direction. However, in a power distribution network with a distributed power supply, a non-directional fault indicator is not applicable any more, and therefore the bidirectional fault indicator with the communication capability is adopted in the invention;

step 2: establishing an adjacency list reflecting the structural state of the power distribution network; the established adjacency list reflecting the structure state of the power distribution network is prepared for correcting the state information of the fault indicators in the next step, the numbers of the fault indicators, the numbers of the upstream and downstream fault indicators of each fault indicator and the state information of the fault indicators are displayed in the adjacency list, and the structure of the power distribution network and the states of the fault indicators can be clearly known from the adjacency list;

the adjacency list is a table showing the adjacency relationship and the state between the failure indicators. Taking FIG. 2 as an example, FI₁In FI₂Upstream, which means that the current is drawn from FI₁Flow direction FI₂. In contrast, FI₂In FI₁Downstream of (c). It is noted that this relationship only exists when the two FIs are adjacent to each other.

Suppose a short-circuit fault occurs at L₆The state of the sector, fault indicator is shown in fig. 4. The adjacency list is shown in table 1. Column 1 of the table 1 shows the numbers of all fault indicators, column 2 is the nearest upstream FIs to the fault indicator in the first column, and the number "0" in this column indicates no upstream fault indicator. Column 3 is downstream FIs closest to the fault indicator in the first column, again, the number "0" indicates no downstream fault indicator. Column 4 is the status information of the fault indicator and constitutes the FI status information matrix B. The numeral "1" indicates that the device is triggered by the fault current transmitted in the forward direction, and the numeral "0" indicates that the device is transmitted in the reverse directionThe incoming fault current is triggered or no fault current is detected.

TABLE 1 faults occur at L₆Adjacency list of sectors

Number of sequences	Upstream fault indicator	Downstream fault indicator	Fault indicator status
				1	0	FI ₂	1
2	FI₁	FI₃	1
				3	FI₂	FI₄、FI ₇	1
4	FI₃	FI₅	0
				5	FI₄	FI₆	0
6	FI ₅	0	0
				7	FI₃	FI₈	1
8	FI₇	FI₉	0
				9	FI ₈	0	0

And step 3: correcting the state information of the fault indicator by using an iterative method so as to obtain a state information matrix B of the fault indicator; the iterative method is used to correct the status information of the fault indicator in order to obtain an accurate status information matrix B. Because the fault indicator is usually installed outdoors and is subjected to severe environment all the year round, the phenomenon of information loss is easy to occur, and the fault indicator has strong dependence on the accuracy of the state information, so that the iterative method is adopted to correct the state information, and the accurate information state matrix B is obtained;

the step 3 specifically comprises the following steps:

step 3.2: determining the state of the fault indicator m;

step 3.5: determining a state of an mth fault indicator;

The power distribution network section fault of figure 5 is applied to verify the validity of the iterative method. In the figure, L₅And L₇In case of failure, FI₂、FI₄、FI₇There are situations where information is lost. Its adjacency list is shown in table 2.

TABLE 2L₅And L₇In case of failure, FI₂、FI₄、FI₇Adjacency list with information loss

The FI status information is corrected according to an iterative method, as shown in table 3.

TABLE 3 FI status information correction Table

As can be seen from Table 3, FI₂、FI₄、FI₇There is a problem of information loss, which is exactly the same as what is assumed. Before operation, the state information is verified by an iteration method, which is beneficial to improving the positioning accuracy.

In this embodiment, the validity of the method is verified by taking fig. 2 as an example. Suppose L₆When a segment fails and the FI status information is not lost, the status information matrix B is [ 111000100 ] as shown in fig. 4]^TAccording to B ═ AC, the solution is solved to C ═ 000001000]^T. As can be seen from the matrix C, the 6 th digit is 1, indicating L₆A failure has occurred.

Since the FI is usually installed in a severe environment such as the open air, the collected information is inevitably lost, which may result in inaccurate fault location.

Suppose a faulty section L₄In case of failure, FI₂Lost due to failure, so that B is [ 101100000 ]]^TCalculating to obtain C ═ 1-10100000]^TFrom matrix C, it can be seen that sectors 1 and 4 have failed, which results in a fault location error, and an iterative method is used to solve this problem.

The embodiment also performs simulation verification and analysis on the scheme, and the tested power distribution network is from a power company in taiwan, and the power distribution network system of the test is shown in fig. 6. The positioning of the fault section of the power distribution network is realized through the steps, and the specific implementation steps are as follows:

3 distributed power sources are added to the power distribution network shown in FIG. 6 and are respectively added to the section L₁₉、L₂₃、L₃₀After and before the distributed power supplyA breaker is added and a fault indicator is installed on the breaker, as shown in detail in fig. 7.

In fig. 7, 3 virtual feeder sections, L respectively, need to be added₃₆、L₃₇、L₃₈. As the fault indicator and the feeder line section are added, the incidence matrix A is established according to the step of establishing the incidence matrix, as shown in the formula (2);

suppose that the feeder section L₁₉And L₂₆A failure occurs and the failure indicators 7 and 24 lose information. The information state is shown in fig. 8, the adjacency list corresponding to fig. 7 is established, as shown in table 4, and the state information in the adjacency list is corrected by using an iterative method, as shown in table 5. It can be seen from the table that the fault indicators 7 and 24 have lost information, which is consistent with the assumption that the final fault information matrix B is obtained [ 11111110000001100010010111000000000000 ]]^T(ii) a Obtaining C ═ 0000000010000001000000000000 by the formula B ═ A ═ C]^TFrom the matrix C, the feeder sections L can be obtained₁₉And L₂₆A failure has occurred.

TABLE 4L₁₉And L₂₆Adjacency list with failure and loss of information for failure indicators 7 and 24

TABLE 5 FI status information Table

From experimental results, the method can accurately and quickly locate the fault section even if the fault indicator information is lost.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions and scope of the present invention as defined in the appended claims.

Claims

1. A power distribution network fault section positioning method based on a fault indicator is characterized in that: the method comprises the following steps:

the step 1 specifically comprises:

step 1.4: let k₀1 is used as the initial number of the fault indicator, i is the number of the fault indicator, and j is the number of the feeder line section; the elements in the incidence matrix A are defined as status information of the fault indicator i when the feeder section j fails, i.e. a_ij；

step 1.6: let k₀Self-increment by 1, and then return to the step 1.5;

step 1.7: up to k₀Obtaining the maximum value M of the fault indicator number and finishing the step 1.5, and then finishing the program; otherwise, returning to the step 1.6;

the step 3 specifically includes:

step 3.2: determining the state of the fault indicator m;

step 3.5: determining a state of an mth fault indicator;

step 3.7: detecting the value of m, and stopping the program if the value of m is equal to 1; otherwise, returning to the step 3.4;

and 4, step 4: the data processing unit solves a matrix C by using a formula B which is AC, wherein C is a feeder line section state matrix, and a positive value in C is a fault section;

the fault indicator uses a bi-directional fault indicator; when the fault indicator detects a fault current consistent with the set positive direction, the fault indicator lamp is turned on and is represented by a numeral '1', and when a fault current opposite to the set positive direction is detected or the fault current is not detected, the fault indicator lamp is not turned on and is represented by a numeral '0';