Fault positioning method for power distribution network containing distributed power supply

Abstract

The invention discloses a distributed power supply-containing power distribution network fault positioning method, which belongs to the technical field of power distribution fault positioning, and comprises the following steps: S1, collecting fault information transmitted by a power distribution switch monitoring terminal through a data acquisition monitoring system; s2, constructing a power distribution network fault positioning mathematical model; s3, according to the power distribution network fault positioning mathematical model, analyzing the fault information to position a fault position; and S4, isolating a fault area and recovering power supply of a non-fault section. According to the invention, fault positioning and isolation operation can be rapidly completed, the positioning accuracy is high, and the power supply reliability is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution fault location, and in particular to a method for locating a power distribution network fault containing a distributed power source. Background Art

[0002] With the vigorous development of distribution network automation, a large number of distributed generators (DG) are gradually connected to the distribution network, making the traditional distribution network more complicated. Power supply bureaus in various places have successively carried out the design and construction of intelligent distributed feeder automation. With the widespread use of feeder terminal units (FTU), intelligent distributed feeder automation is replacing traditional feeder networks to complete the monitoring and protection of distribution networks. The use of intelligent algorithms to locate faults through intelligent terminal communication has become the mainstream of current research. However, there is no intelligent algorithm for fault location in distribution networks containing distributed generators in the existing technology. Summary of the invention

[0003] In view of this, the present invention aims at the deficiencies of the prior art and provides a method for locating faults in a power distribution network containing distributed power sources, which can quickly complete fault locating and isolating operations, thereby greatly improving power supply reliability.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for locating a fault in a power distribution network containing a distributed power source, comprising the following steps:

[0005] S1. Collect fault information from the distribution switch monitoring terminal through the data acquisition monitoring system;

[0006] S2, construct a mathematical model for fault location in distribution network;

[0007] S3, analyzing the fault information to locate the fault location according to the distribution network fault location mathematical model;

[0008] S4. Isolate the faulty area and restore power supply to the non-faulty sections.

[0009] Furthermore, in S2, the method for constructing a distribution network fault location mathematical model includes:

[0010] Step 1: Define the switch code of the distribution network including the distributed generation;

[0011] Step 2: Construct a distribution network switch planning model without distributed generation;

[0012] Step 3: Based on the distribution network switch planning model without distributed generation, the distribution network switch planning model with distributed generation is improved to obtain;

[0013] Step 4: Use the fitness function to optimize the switch planning model of the distribution network containing distributed generation to achieve accurate fault location.

[0014] Furthermore, in step 1, the switch coding of the distribution network containing distributed power sources is defined: the current direction of the main power source is the positive direction, the section on one side of the main power source is the upstream of the node, and the section on the other side is the downstream; when the distribution switch monitoring terminal detects the positive direction fault current information, the switch coding is 1; when the negative direction fault current information is detected, the switch coding is -1; if there is no fault current flowing through the node, the coding is 0; expressed by the following formula:

[0015]

[0016] Among them, I j Indicates the current information uploaded at the j-th segment.

[0017] Further, in step 2, the distribution network switch planning model without distributed generation includes a distribution network switch function without distributed generation:

[0018]

[0019] Where: I j (s) is the value of the switch function; ∏ represents the logical OR operation; s i The meaning is the status value of the i-th line section downstream of node j. The value is 1 when a fault occurs and 0 when the section status is normal.

[0020] Furthermore, in step 3, the distribution network switch planning model including the distributed generation includes the distribution network switch function including the distributed generation:

[0021]

[0022]

[0023]

[0024] When node j is taken as the target, the distribution network containing distributed generation is divided into two parts, the side close to the main power source is the upstream, and the other side is the downstream; K in the formula u , K d They represent the switching coefficients of the upstream and downstream power supplies of switch j, respectively. When the power supply is put into operation, the value is 1, and when it is turned off, it is 0; M2 and N2 represent the total number of feeder sections in the upper and lower sections of switch j, respectively; M1 and N1 represent the total number of power supplies in the upper and lower halves of switch j, respectively; s j,u 、s j,d are the state values ​​of all feeder sections from switch j to the upper and lower sections, respectively. The value is 1 when a fault occurs and the value is 0 when the section is normal. j,Gu、s j,Gd The jth switch to the upstream system power supply G u With downstream distributed power supply G d The state value of the feeder section passed on the path; ju (s), I jd (s) represents the switch function of the upstream and downstream lines of the jth switch; I j (s) represents the switching function of the jth switch; П represents the logical OR operation.

[0025] Furthermore, in step 4, the fitness function is used to optimize the switch planning model of the distribution network containing distributed generation:

[0026]

[0027] I in the formula h Indicates the fault overcurrent information of the hth section; I h * (S) is the switching function of the hth section; H is the total number of sections in the entire distributed feeder network; x(h) is the fault state of the hth section, which is 1 when a fault occurs and 0 otherwise; μ is the weight coefficient, which ranges from 0 to 1.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention provides a method for locating a fault in a distribution network containing a distributed power source, constructs a distribution network fault location mathematical model, analyzes the fault information collected by a data acquisition monitoring system and transmitted from a distribution switch monitoring terminal to locate the fault location, isolate the fault area, and restore power supply to non-faulty sections. The present invention constructs a distribution network fault location mathematical model, uses an intelligent algorithm to locate the fault section through an intelligent terminal, and can quickly complete the fault location and isolation operation. The processing time of the entire location and isolation process is in seconds, which greatly improves the power supply reliability.

[0030] The present invention provides a method for locating faults in a distribution network containing distributed power sources, improves a traditional distribution network switch function that does not contain distributed power sources, obtains a distribution network switch function that contains distributed power sources, and is used to determine the section where the fault is located. The algorithm is optimized using a fitness function to achieve more accurate fault location. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described in combination with the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0032] A method for locating a fault in a power distribution network including a distributed power source comprises the following steps:

[0033] S1. Collect fault information from the distribution switch monitoring terminal through the data acquisition monitoring system;

[0034] S2, construct a mathematical model for fault location in distribution network;

[0035] S3, analyzing the fault information to locate the fault location according to the distribution network fault location mathematical model;

[0036] S4. Isolate the faulty area and restore power supply to the non-faulty sections.

[0037] Specifically, in S2, the method for constructing a distribution network fault location mathematical model includes:

[0038] Step 1: Define the switch code of the distribution network including the distributed generation;

[0039] Step 2: Construct a distribution network switch planning model without distributed generation;

[0040] Step 3: Based on the distribution network switch planning model without distributed generation, the distribution network switch planning model with distributed generation is improved to obtain;

[0041] Step 4: Use the fitness function to optimize the switch planning model of the distribution network containing distributed generation to achieve accurate fault location.

[0042] The distribution switch monitoring terminal of the distributed feeder switch node of the distribution network can detect whether the node has overcurrent information. In the traditional distribution network, there is no access to distributed power sources, and the current direction output by the main power supply of the distribution network is only one, so the encoding of the feeder status is only 0 and 1. The rule is: 0 means that the node has no overcurrent information, and 1 means that the node has overcurrent information. Therefore, 1 can be used to represent a section fault, and 0 can be used to represent a section without fault. Therefore, the fault status positioning of each feeder section can be transformed into an N-dimensional binary particle swarm optimization solution, where the dimension represents the number of distributed feeder sections in the distribution network.

[0043] When the distribution network is connected to a distributed power source, the current direction will change due to the access of the distributed power source, so the switch coding method must be changed. In step 1, the switch coding of the distribution network containing distributed power sources is defined: the current direction of the main power source is the positive direction, the section on the main power source side is the upstream of the node, and the section on the other side is the downstream; when the distribution switch monitoring terminal detects positive fault current information, the switch coding is 1; when negative fault current information is detected, the switch coding is -1; if there is no fault current flowing through the node, the coding is 0; expressed by the following formula:

[0044]

[0045] Among them, I j Indicates the current information uploaded at the j-th segment.

[0046] In traditional distribution networks without distributed power sources, the switching function is based on a single-power radial line design. This function is relatively simple and represents the logical OR operation of the status of all line sections downstream of a node.

[0047] In step 2, the distribution network switch planning model without distributed generation includes the distribution network switch function without distributed generation:

[0048]

[0049] Where: I j (s) is the value of the switch function; ∏ represents the logical OR operation; s i The meaning is the status value of the i-th line section downstream of node j. The value is 1 when a fault occurs and 0 when the section status is normal.

[0050] With the continuous development of the power grid, more and more distributed power sources are connected to the distribution network, which changes the topology of the entire distribution network. The upstream and downstream relationships of the feeders will change due to the switching of distributed power sources, so it is necessary to improve the traditional switching function.

[0051] In step 3, the distribution network switch planning model including distributed generation includes the distribution network switch function including distributed generation:

[0052]

[0053]

[0054]

[0055] When node j is taken as the target, the distribution network containing distributed generation is divided into two parts, the side close to the main power source is the upstream, and the other side is the downstream; K in the formula u , K dThey represent the switching coefficients of the upstream and downstream power supplies of switch j, respectively. When the power supply is put into operation, the value is 1, and when it is turned off, it is 0; M2 and N2 represent the total number of feeder sections in the upper and lower sections of switch j, respectively; M1 and N1 represent the total number of power supplies in the upper and lower halves of switch j, respectively; s j,u 、s j,d are the status values ​​of all feeder sections from switch j to the upper and lower sections, respectively. The value is 1 when a fault occurs and the value is 0 when the section is normal. j,Gu 、s j,Gd The jth switch to the upstream system power supply G u With downstream distributed power supply G d The state value of the feeder section passed on the path; ju (s), I jd (s) represents the switch function of the upstream and downstream lines of the jth switch; I j (s) represents the switching function of the jth switch; П represents the logical OR operation.

[0056] In step 4, the fitness function is used to optimize the switch planning model of the distribution network containing distributed generation:

[0057]

[0058] I in the formula h Indicates the fault overcurrent information of the hth section; I h * (S) is the switching function of the hth section; H is the total number of sections in the entire distributed feeder network; x(h) is the fault state of the hth section, and its value is 1 when a fault occurs, otherwise it is 0; in order to avoid misjudgment of the faulty section due to distortion or loss of information collected by the distribution switch monitoring terminal, the algorithm cannot obtain the optimal value, so the "minimum set" in the fault diagnosis theory is introduced, μ is the weight coefficient, and its value range is 0 to 1. In the embodiment of the present invention, it takes a value of 0.5.

[0059] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for locating faults in a power distribution network containing distributed power sources, characterized in that: The following steps are involved: S1. Collect fault information from the distribution switch monitoring terminal through the data acquisition monitoring system; S2, construct a mathematical model for fault location in distribution network; S3, analyzing the fault information to locate the fault location according to the distribution network fault location mathematical model; S4. Isolate the faulty area and restore power supply to the non-faulty sections.

2. The method for locating a fault in a power distribution network containing a distributed power source according to claim 1, characterized in that: In S2, the method for constructing a distribution network fault location mathematical model includes: Step 1: Define the switch code of the distribution network including the distributed generation; Step 2: Construct a distribution network switch planning model without distributed generation; Step 3: Based on the distribution network switch planning model without distributed generation, the distribution network switch planning model with distributed generation is improved to obtain; Step 4: Use the fitness function to optimize the switch planning model of the distribution network containing distributed generation to achieve accurate fault location.

3. The method for locating a fault in a power distribution network containing a distributed power source according to claim 2, characterized in that: In step 1, the switch coding of the distribution network containing distributed power sources is defined: the current direction of the main power source is the positive direction, the section on one side of the main power source is the upstream of the node, and the section on the other side is the downstream; When the distribution switch monitoring terminal detects positive fault current information, the switch code is 1; when negative fault current information is detected, the switch code is -1; if no fault current flows through the node, the code is 0; It is expressed by the following formula: Among them, I j Indicates the current information uploaded at the j-th segment.

4. The method for locating faults in a power distribution network containing distributed power sources according to claim 3, characterized in that: In step 2, the distribution network switch planning model without distributed generation includes the distribution network switch function without distributed generation: Where: I j (s) is the value of the switch function; ∏ represents the logical OR operation; s i The meaning is the status value of the i-th line section downstream of node j. The value is 1 when a fault occurs and 0 when the section status is normal.

5. The method for locating faults in a power distribution network containing distributed power sources according to claim 4, characterized in that: In step 3, the distribution network switch planning model including distributed generation includes the distribution network switch function including distributed generation: When node j is taken as the target, the distribution network containing distributed generation is divided into two parts, the side close to the main power source is the upstream, and the other side is the downstream; K in the formula u , K d They represent the switching coefficients of the upstream and downstream power supplies of switch j, respectively. When the power supply is put into operation, the value is 1, and when it is turned off, it is 0; M2 and N2 represent the total number of feeder sections in the upper and lower sections of switch j, respectively; M1 and N1 represent the total number of power supplies in the upper and lower halves of switch j, respectively; s j,u 、s j,d are the status values ​​of all feeder sections from switch j to the upper and lower sections, respectively. The value is 1 when a fault occurs and the value is 0 when the section is normal. j,Gu 、s j,Gd The jth switch to the upstream system power supply G u With downstream distributed power supply G d The state value of the feeder section passed on the path; ju (s), I jd (s) represents the switch function of the upstream and downstream lines of the jth switch; I j (s) represents the switching function of the jth switch; П represents the logical OR operation.

6. The method for locating faults in a power distribution network containing distributed power sources according to claim 5, characterized in that: In step 4, the fitness function is used to optimize the switch planning model of the distribution network containing distributed generation: I in the formula h Indicates the fault overcurrent information of the hth section; I h * (S) is the switching function of the hth section; H is the total number of sections in the entire distributed feeder network; x(h) is the fault state of the hth section, which is 1 when a fault occurs and 0 otherwise; μ is the weight coefficient, which ranges from 0 to 1.

Images