CN105759173B - The adaptive failure Section Location of power distribution network containing distributed generation resource - Google Patents

Abstract

An adaptive fault section location method for a distribution network with distributed power sources, which divides the distribution network with distributed power sources into multiple double-ended and branchless sections. Under the condition that the line parameters of all sections are known, the voltage and current information at the nodes at both ends of each section are collected, and the mode voltage and current at the node and the mode parameters of the line are obtained through phase-mode transformation. The mode current of the node is obtained by Fu The phase angle of the nodal mode current is obtained by the Lie transform. Using the line no-load detection and differential current detection of the section, the fault judgment of the section is started only when the line in the section is not unloaded and the differential current of the section is overcurrent. Comparing the absolute value of the phase angle difference of the mode current with the judgment threshold, the fault judgment result of the section is obtained. The system fault judgment matrix is generated by using the fault judgment results of all sections in the distribution network containing distributed power generation, and the section where the fault point is located is obtained by judging the element values in the system fault judgment matrix.

Description

Adaptive fault location method for distribution network with distributed generation

technical field

The invention relates to a method for locating a fault section of a distribution network with a distributed power supply.

Background technique

The distribution network fault location technology can accurately find out the location of the fault after the distribution network fault, which is conducive to the accurate isolation of the distribution network fault and the rapid and timely maintenance and treatment. At the same time, the accurate location of the distribution network fault is also a prerequisite for the restoration of the power supply of the distribution network after the fault. Therefore, distribution network fault location technology has an important significance and effect on the safe, stable and efficient operation of the entire distribution network.

With the maturity of distributed generation technology and the progress of micro-grid operation control technology, more and more distributed generators (Distributed Generators, DG) are continuously connected to the distribution network, making the traditional passive distribution network into a distribution network. In the active distribution network of distributed power supply, the two-way power flow, the fluctuation of distributed power output and the low short-circuit current output characteristics of inverter distributed power make the setting of traditional distribution network protection and fault location methods more difficult. , and it is easy to cause false movement and refusal to move, so it is no longer applicable.

Chinese invention patent 201210532103.3 discloses a method for determining the fault interval of a distribution network containing DG based on the short-circuit fault characteristics of the impedance model. This method obtains the current threshold for fault interval judgment by establishing an analysis model. In practical applications, it is affected by the accuracy of the model parameters and the Network operation topology changes have a great impact and are not self-adaptive. Chinese invention patent 201510170001.5 discloses a distribution network fault location method based on FTU. This method uses matrix algorithm to determine the fault location. The accuracy of the location depends on the correct judgment of each FTU on the node's overcurrent situation and reliable communication. Wrong fault information or signal distortion may lead to reduced accuracy or even errors in fault location. In "Isolation of Faults in Distribution Networks with Distributed Generators" written by N.Perera et al. in "IEEE TRANSACTIONS ON POWER DELIVERY", Volume 23, Issue 4, 2008, the location of the fault section is realized by comparing the signs of the wavelet coefficients, but the wavelet algorithm It is tedious and complex, requires high sampling rate and data processing capability of hardware, and high configuration cost makes it difficult to realize application in distribution network.

At present, domestic and foreign studies on fault location of distribution networks with distributed generation mostly use node current as the main source of fault characteristic information, that is, these methods are used to determine the location of faults in distribution networks with distributed generation. The characteristic quantities are all node currents or generated by transforming or processing node currents. Considering that the distribution network with distributed power has a complex topology, a wide variety of equipment and high frequency of operation, the output of distributed power is easily affected by environmental factors and fluctuates, and the operating status of the entire network will change from time to time, which makes The judgment thresholds at each node in the entire network need to be calculated and adjusted in real time, otherwise the accuracy and reliability of fault location cannot be guaranteed. Therefore, when the fault location method using node current as the source of fault characteristic information is applied in a distribution network with distributed power generation, it must be configured with a corresponding threshold real-time update mechanism. Adaptability necessary for reliability and efficiency. However, the state information of the entire network must be collected every time the threshold is set, and the calculation of the threshold will generate a considerable amount of calculation. The update of the threshold needs to be supported by a high-speed and reliable communication system. However, it is difficult to quickly track the changes of the system's operating state, which leads to the lack of adaptability of these methods.

With the continuous improvement of the distributed power penetration rate in the distribution network and the development of the smart distribution network, the intelligent distribution network in the future will have a higher distributed power penetration rate and a more flexible topological structure. Power generation and power consumption have a greater degree of freedom and strong volatility, which will put forward higher requirements for the ability of the fault location method to adapt to complex and changeable operating conditions, that is, the fault location method is required to have a strong self-adaption sex. Therefore, the existing fault location methods for distribution networks with distributed generation cannot adapt to the development trend of smart distribution networks.

To sum up, in the trend of smart distribution network development, in the face of the high penetration rate of distributed power distribution network with distributed power, rapid protection, small-scale fault isolation, and power supply recovery after faults to achieve system self-healing According to the actual demand, a faster, more effective, and better adaptive online fault location method is still needed in the distribution network with distributed power generation.

Contents of the invention

The purpose of the present invention is to propose a self-adaptive fault section suitable for the distribution network containing distributed power in view of the insufficient self-adaptability existing in the fault location method of the distribution network containing distributed power positioning method.

The present invention can realize online fault section positioning in the distribution network containing distributed power sources, and various faults can occur in the distribution network containing distributed power sources, such as single-phase ground short circuit, two-phase ground short circuit, two-phase In the case of phase-to-phase short circuit and three-phase short circuit, it can quickly, accurately and reliably locate faults, and is not affected by non-fault disturbances. It has good adaptability and versatility, and is suitable for multiple types of lines at the same time, such as single-phase Line, two-phase line, three-phase line distribution network with distributed power supply.

The technical scheme that the present invention takes is:

The method of the present invention first divides a distribution network containing distributed power sources into sections, and numbers each node and section in the distribution network containing distributed power sources; then, collects the distribution network containing distributed power sources The voltage and current signals at the nodes at both ends of each section in the network, use the designed phase-mode transformation matrix to perform phase-mode transformation on the section, convert the coupled electrical quantities in the section into mutually independent modulus, and obtain each The modulus corresponds to the mode voltage, mode current, series mode impedance and parallel mode admittance per unit length of the line. Then, choose an appropriate modulus for section fault judgment. After the line no-load detection and differential current detection of the section, only when the line in the section is not empty and the differential current of the section is overcurrent, the judgment of the section fault is carried out. After entering the section fault judgment process, obtain the absolute value of the mode current phase angle difference of the section corresponding to the modulus selected for section fault judgment, and pass the absolute value of the mode current phase angle difference obtained The comparison with the decision threshold yields a fault decision result for the segment. Finally, using the fault judgment results of each section in the distribution network containing distributed generation, according to the generation and judgment method of the system fault judgment matrix, the fault judgment and fault location of the distribution network containing distributed generation are carried out, and the obtained The fault location result at the current moment.

The concrete steps of the inventive method are as follows:

(1) Segmentation of the distribution network with distributed power generation

The section division method of the distribution network containing distributed power sources is as follows: in a distribution network containing distributed power sources, the distribution network is divided into several double-ended and branch-free sections according to its topology, that is, Each divided section has one and only two end nodes, and the section has no other branch roads between the two end nodes. After completing the section division, number the nodes and sections, and give each node and section a unique number.

(2) Perform phase-mode transformation on the section of the distribution network containing distributed power, and convert the coupled electrical quantities in the section into mutually independent moduli

On the basis of step (1), the voltage and current signals at the nodes at both ends of each section in the distributed power distribution network are collected, and the phase-mode transformation is performed on the section by using the designed phase-mode transformation matrix, and the section The electrical quantity coupled in the section is transformed into mutually independent moduli, and the corresponding mode voltage, mode current, series mode impedance and parallel mode admittance of the unit length of the line are obtained for each modulus.

(1) The design method of described phase mode transformation matrix is as follows:

In general, distribution networks with distributed power sources often contain three-phase lines, two-phase lines and single-phase lines at the same time, and the corresponding three-phase sections, two-phase sections and single-phase sections are formed after section division . For a certain n-phase section in the distribution network with distributed power generation, n=1, 2, 3, let the line in this section take its end node as the origin of the length, and the positive direction of the line length change is The origin points to the node at the other end of the section. It can be defined that the voltage matrix at a certain point along the positive radial direction of the section is U _(n) (x), and the current matrix flowing through this point is I _(n) (x), the corresponding expression form is as follows:

Among them, U _i (x) is the phase voltage of the i-th phase at the point of the line length x in the section; I _i (x) is the phase current of the i-th phase at the point of the line length x in the section, i=1,...,n.

According to the distribution parameter model of the transmission line, the series impedance matrix of the unit length of the line in this section can be defined as Z _(n) in Ω/km; the parallel admittance matrix is Y _(n) in S/km. The form of the corresponding expression is as follows:

Among them, z _ij , i=j, represents the series self-impedance per unit length of the line in this section; z _ij , i≠j, represents the series mutual impedance of the line unit length in this section; y _ij , i=j, represents The parallel self-admittance per unit length of the line in this section; y _ij , i≠j, represents the parallel mutual admittance per unit length of the line in this section.

Therefore, the differential equation of the distributed parameter model of the line in this section can be written:

After research, it can be obtained that if there is a matrix Φ _(n) that satisfies the conditions described in the following formula:

Φ _(n) ^-1 · (Z _(n) · Y _(n) ) · Φ _(n) = λ _(n) (3)

in, λ _(n) = diag(λ ₁₁ ,…,λ _nn ), which is the characteristic root matrix of formula (3). Then, the matrix Φ _(n) is used to transform the electrical phasor and line parameters on the line in this section, so as to realize the decoupling of the coupling phasor and parameters.

The phase-mode transformation formula that can be used in a certain section of the distribution network with distributed power generation is as follows:

Use the matrix Φ _(n) to decouple the line parameters of the mutual coupling between the phases in the line in the section, and transform the coupled electrical phasors in the line in the section into independent electrical mode components, called phase mode Transformation, the transformation formula is as follows:

in, is the node voltage modulus matrix at a certain point in the section obtained by phase mode transformation; is the node current modulus matrix at a point in the section obtained by phase mode transformation; is the series-mode impedance matrix of the unit length of the line in the section obtained through phase-mode transformation; is the parallel mode admittance matrix of the line unit length in the section obtained by phase-mode transformation.

According to formula (1), formula (2), formula (4), formula (5), formula (6) and formula (7), the distributed parameter model equivalent to the line in this section obtained by phase mode transformation can be derived The differential equation for :

In the above equivalent model, select a certain modulus k, k=1,...,n, that is, select the equivalent single-phase section formed by the kth modulus in the equivalent model of the line in this section, According to formula (8) and formula (9), the differential equation of the distributed parameter model of the equivalent single-phase section can be written:

in, and are the node-mode voltage and node-mode current at a point in the section obtained through phase-mode transformation, respectively; and are the series-mode impedance and parallel-mode admittance of the line unit length in the section obtained through phase-mode transformation, respectively.

The node mode voltage in the single-phase section equivalent to the kth modulus obtained by phase-mode transformation of an n-phase section Nodal mode current The essence of is the linear combination of the voltage phasor and current phasor of each phase in the n-phase segment. According to the principle of phasor superposition, the sum of phasors at the same frequency is still the phasor at this frequency, and its mathematical expression is as follows:

In formula (12) and formula (13), s _i is the coefficient of the linear combination of voltage phasors of each phase in the n-phase section, v _i is the coefficient of the linear combination of current phasors in each phase of the n-phase section, i= 1,...,n. By selecting appropriate s _i and v _i , the change of a single modulus can be used to reflect the change of each phasor in the n-phase segment. Therefore, to select an appropriate _value of v, the phase angle difference of the phase current of the equivalent single-phase section of the n-phase section can be used to replace the phase angle difference of the phase current of each phase section to determine the occurrence in this section Various types of faults, including: single-phase ground short circuit, two-phase ground short circuit, two-phase phase-to-phase short circuit, three-phase short circuit, a total of four major types of faults.

Considering that the value of the coefficient _si of the linear combination of the voltage phasors of each phase in the n-phase section is actually the value of the element in the kth row and column i in the node voltage phase-mode transformation matrix, and the linearity of the current phasors of each phase in the n-phase section The value of the combined coefficient v _i is actually the value of the kth row and ith column element in the node current phase-mode transformation matrix. In order to make the n-phase section reflect the kth modulus obtained by phase-mode transformation in the case of various faults, such as single-phase ground short circuit, two-phase ground short circuit, two-phase phase-to-phase short circuit, and three-phase short circuit The fault of the equivalent single-phase section, that is, when a fault occurs in the n-phase section, a fault occurs in the single-phase section equivalent to the kth modulus obtained by phase-mode transformation, which requires The value of each element in the matrix Φ _(n) is designed and selected according to certain rules.

If the line parameters in the n-phase section are transposition balanced, the following formula holds:

in, is the parameter matrix of the line in the n-phase section, and α is the matrix Inner diagonal elements, β is the matrix Inner off-diagonal elements, obviously is a symmetric matrix.

In order to decouple the coupled line parameters in this n-phase segment, a symmetric transformation matrix is required satisfy the following formula:

in, is the characteristic root matrix of formula (15).

However, considering that the line parameters in the actual distribution network with distributed generation are not transposition balanced, except for single-phase lines, for two-phase sections or three-phase sections with non-transposition balanced line parameters, its The line parameter matrix K _(n) becomes:

Among them, n is the phase number of the line in the section; K _(n) is a symmetrical matrix, and κ _ij = κ _ji is established, i=1,...,n, j=1,...,n, and i≠j . use matrix It is impossible to turn K _(n) into a diagonal matrix, so it is necessary to find a matrix Φ _(n) that can turn K _(n) into a diagonal matrix, and decouple the mutually coupled lines in the section, which can be achieved through the following Methods The phase-mode transformation matrix suitable for non-transposition balance of line parameters in the section is designed.

The design method of the phase-mode transformation matrix considering the non-transposition balance of line parameters is as follows:

This method first needs to know the number of phases n in the section, the fundamental frequency f of the voltage and current phasors, the series resistance matrix R _(n) of the line unit length in the section, the unit is Ω/km, and the series inductance matrix L _(n) , the unit is H/km, and the parallel capacitance matrix C _(n) , the unit is F/km, their mathematical expressions are respectively:

Among them, r _ij represents the series self-resistance of the line unit length in this section, i=j; r _ij represents the series mutual resistance of the line unit length in this section, i≠j; l _ij represents the line unit length in this section The series self-inductance of the line, i=j; l _ij represents the series mutual inductance of the line unit length in this section, i≠j; c _ij represents the parallel self-capacitance of the line unit length in this section, i=j; c _ij represents the Parallel mutual capacitance of line unit length in the section, i≠j.

The design method of the phase-mode transformation matrix of the line parameter non-transposition balance comprises the following eight steps:

Step 1. Obtain the parameter matrix K _(n) of the lines in the section. The calculation of K _(n) can be based on the following calculation formula:

K _(n) = [R _(n) + j (2πf) L _(n) ] [j (2πf) C _(n) ] (16)

Among them, j ² =-1.

Step 2, calculate the matrix of the line parameter transposition balance corresponding to the line parameter matrix K _(n) matrix The calculation method is as follows:

like

then there is

where α and β respectively satisfy the following formulas:

Step 3. Design Matrix the matrix Written in the form shown below:

Among them, a _ij is the element in the matrix, and a _ij = a _ji is established, i=1,...,n, j=1,...,n, and i≠j; A is the coefficient of the matrix, and there is

According to the phase number n of the section, the matrix is arranged according to the three constraint rules as shown below The value of each element in the design:

① When n=1, that is, the section is a single-phase section, The elements in should satisfy the constraints described in the following formula: a ₁₁ =1

②When n=2, that is, the section is a two-phase section, The elements in should satisfy the constraints described in the following formula:

③When n=3, that is, the section is a three-phase section, The elements in should satisfy the constraints described in the following formula:

Step 4. Calculate the matrix The eigenvalue matrix of matrix The eigenvalue matrix of can be calculated according to the following formula:

Step 5. Use the matrix and matrix K _(n) , computing the matrix matrix The calculation formula is:

Step 6. Calculate the first-order disturbance matrix W _(n) .

First order perturbation matrix

Among them, w _ij is the element in the matrix W _(n) , i=1,...,n, j=1,...,n, and satisfy the following conditions:

Step 7. Calculate the transformation matrix Φ _(n) of the matrix K _(n) . The transformation matrix Φ _{(n ) of the calculation matrix K (n)} can be based on the following calculation formula:

Among them, E _(n) is an n-order identity matrix.

Step 8: Perform Schmidt diagonalization on the transformation matrix Φ _(n) , and after matrix transposition, the required phase-mode transformation matrix Φ _(n) ^T can be finally obtained.

Using the above method, no matter whether the line parameters in the n-phase section are transposition balance or not, the phase-mode transformation matrix of this section can be designed, and the phase-mode transformation matrix Φ _(n) ^T applicable to this section can be obtained. The phase-to-mode transformation matrix Φ _(n) ^T can equivalently convert n mutually coupled electrical phasors in the section into n mutually independent electrical moduli.

(2) the transformation formula of described phase mode transformation is as follows:

If the matrix Φ _(n) ^T is the phase-mode transformation matrix obtained by the design method of the phase-mode transformation matrix considering the line parameter non-transposition balance, then Φ _(n) ^-1 = Φ _(n) ^T is established, so the formula ( 4), formula (5), formula (6) and the phase-mode transformation formula described in formula (7) are simplified, draw the phase-mode transformation formula that the present invention adopts being applicable to the distribution network that contains distributed power supply, specifically as follows :

Let the node voltage matrix at any node in a certain n-phase section in the distribution network containing distributed power generation be U _(n) and the node current matrix be I _(n) , the series impedance of the unit length of the line where the node is located The matrix is Z _(n) , and the parallel admittance matrix per unit length of the line where the node is located is Y _(n) , where:

Then there is the following phase-mode transformation formula, which can realize the decoupling of electrical quantities and line parameters in this section:

in, is the node-mode voltage matrix obtained through phase-mode transformation; is the node-mode current matrix obtained through phase-mode transformation; is the series-mode impedance matrix of the unit length of the line in the section obtained through phase-mode transformation; is the parallel mode admittance matrix of the line unit length in the section obtained by phase-mode transformation.

(3) Analysis of the phase angle difference of the mode current in the section of the distribution network containing distributed power

The definition of the mode current phase angle difference of a section in a distribution network containing a distributed power source is as follows: For a certain section in a distribution network containing a distributed power source, let the node numbers at both ends of the section be p, q, then the mode current phase angles corresponding to the mode currents I _p and I _q at nodes p and q are θ _p and θ _q respectively. If the specified positive direction of the mode current in this section is from node p to node q, Then the phase angle difference of the mode current in this section can be defined as the difference between the phase angle values of the mode current at the nodes at both ends of the section, and the definition formula is: Δθ=θ _p -θ _q , where Δθ is the node p, The mode current phase angle difference of the segment between q.

The phase angle difference of the mode current of an equivalent single-phase section in the distribution network with distributed power generation under the condition of normal operation and failure in the section is analyzed respectively:

When there is no fault in the equivalent single-phase section, that is, under the condition of normal operation, the modulus voltages at the nodes p and q at both ends of the section are respectively The mode currents at nodes p and q are respectively The positive direction of the current is from node p to node q along the radial direction of the line, and the line length of this section is L, so the distributed parameter model of the equivalent single-phase section can be transformed into a concentrated parameter π-shaped line model. Through phasor analysis, it can be obtained that due to the influence of parallel admittance in the line parameters, the mode current at the nodes p and q at both ends of the equivalent single-phase section and There is a small deviation between Have The existence of leads to the absolute value of the phase angle difference of the modulus current of the equivalent single-phase segment is a small angle greater than 0°, where, It can be estimated using the following formula:

in, is the modulus voltage at one end node p of the equivalent single-phase section, is the modulus voltage at the node q at the other end of the equivalent single-phase section; is the series mode impedance per unit length of the line in the equivalent single-phase section, is the parallel mode admittance per unit length of the line in the equivalent single-phase section; L is the line length in the equivalent section.

When a fault occurs in the equivalent single-phase section, the modulus voltages at the nodes p and q at both ends of the section will become Let the fault mode currents at nodes p and q be respectively The location of the fault point is L _p from node p, and L _q from another node q, so L=L _p +L _q . Assuming that the short-circuit impedance at the fault point is Z _f , the equivalent distributed parameter line model after the section fault can be simplified into a lumped parameter π-shaped line model, which can be obtained by derivation and expression for:

in, is the modulus voltage at one end node p of the equivalent single-phase section after a fault occurs, is the modulus voltage at the node q at the other end of the equivalent single-phase section after a fault occurs; is the series mode impedance per unit length of the line in the equivalent single-phase section, is the parallel mode admittance per unit length of the line in the equivalent single-phase section; Z _f is the short-circuit impedance at the fault point; L _p is the distance from the fault point to node p; L _q is the distance from the fault point to node The length of q.

According to the phasor analysis, in the case of a fault in the equivalent single-phase section, the fault mode current at node p and the fault mode current at node q reverse, there is and The included angle is close to 180°, which makes the absolute value of the phase angle difference of the mode current of the equivalent single-phase section far greater than

(4) Select an appropriate modulus for the judgment of section faults

The selection rules for the modulus used to determine the fault are as follows:

The selection rule for the modulus used to determine the fault is: among the n mutually independent electrical moduli obtained through phase-mode transformation, select a specific modulus so that the The phase angle difference of the analog current can determine various faults that actually occur in the n-phase section, such as: single-phase ground short circuit, two-phase ground short circuit, two-phase phase-to-phase short circuit, and three-phase short circuit. The modulus used for fault determination can be selected according to the following rule of thumb:

①When n=1, that is, the section is a single-phase section, and the phase-mode transformation matrix contains only one row of elements, an equivalent modulus can be obtained after phase-mode transformation, and it is only necessary to directly select this modulus as the fault judgment Modulus utilized;

②When n=2, that is, the segment is a two-phase segment, and the phase-mode transformation matrix contains two rows of elements, after phase-mode transformation, two equivalent moduli can be obtained, and the two modes can be made according to their row labels The quantities are modulus 1 and modulus 2 respectively, and modulus 1 can be preferentially selected as the modulus used for fault judgment;

③When n=3, that is, the section is a three-phase section, and the phase-mode transformation matrix contains three rows of elements. After the phase-mode transformation, three equivalent moduli can be obtained. According to the row labels, the three modules can be The quantities are modulus 1, modulus 2 and modulus 3: considering that modulus 1 is the ground component, it cannot reflect the situation of a three-phase fault, and it is impossible to determine the occurrence of the fault in this case; at the same time, modulus 2 And modulus 3 can reflect various fault conditions: single-phase ground short circuit, two-phase ground short circuit, two-phase phase-to-phase short circuit, three-phase short circuit, therefore, a modulus between modulus 2 and modulus 3 can be selected as the As for the modulus used for fault judgment, if there is no special requirement, modulus 2 can be preferred.

(5) Carry out section line no-load detection and mode current differential current detection, and only when the line in the section is not no-load and the mode current difference of the section flows through the current situation, the judgment of the section fault is carried out, The fault judgment result of the section is obtained.

(1) The no-load detection method for section lines suitable for distribution networks with distributed power sources is as follows:

As mentioned above, in a certain section of the distribution network containing distributed power sources in the present invention, first, through the design method of the phase-mode transformation matrix that considers the non-transposition balance of line parameters described in step (2), the Obtain the phase-mode transformation matrix that is applicable to this section; Then, carry out phase-mode transformation to this section according to the phase-mode transformation formula that is applicable to the distribution network containing distributed power; Then, according to step (4) in According to the selection rules of the modulus used in the fault judgment described above, select the number of the modulus used in this section; finally, according to the equivalent single-phase section fault judgment applicable to the distribution network containing distributed power method, the fault judgment is carried out in the single-phase section equivalent to the selected modulus, and the judgment result obtained is the fault judgment result in this section in the distribution network containing distributed power generation. That is: in a certain section of the distribution network containing distributed power sources, various faults occurring in the section can be judged by a single modulus: single-phase ground short circuit, two-phase ground short circuit, two-phase phase-to-phase fault Short circuit, three-phase short circuit and other faults.

Considering that in the distribution network with distributed power, if the line in one section is in the no-load state, the lower current may cause the measurement error of the current phase angle to increase, which may lead to the application of distributed power. The fault judgment method of the equivalent single-phase section of the power distribution network has a misjudgment, so this method is not suitable for the judgment of the fault in the no-load line section. Therefore, it is necessary to detect whether the line in the section is running in an unloaded state, and block the fault judgment of the section when the line is unloaded.

In the single-phase section equivalent to the kth modulus, let the nodes at both ends of the section be nodes p and q respectively, then the node modulus voltages at nodes p and q in this section are respectively The node-mode currents are The series mode impedance per unit length of the line in this section is The parallel mode admittance is If the length of the line in this section is L, the lumped parameter π-shaped line model of this equivalent single-phase section is analyzed, and the no-load mode current amplitude in this section can be estimated by the following formula:

in, is the nodal-mode voltage at node p in the equivalent single-phase segment, is the node-mode voltage at node q in the equivalent single-phase section; is the parallel mode admittance per unit length of the line in the equivalent single-phase section; L is the length of the line in the equivalent single-phase section.

Based on the above analysis, the section line no-load detection method applicable to the distribution network with distributed power generation first needs to know the modulus number k selected for fault judgment in the section, and the equivalent single-phase area corresponding to the modulus k Nodal modulus voltage at nodes p and q at both ends of the segment Nodal mode current The series mode impedance of the unit length of the line in the equivalent single-phase section and parallel mode admittance The length L of the line in the section, and the rated voltage amplitude U _nom of the line in the section. The method consists of three steps as follows:

Step 1. Calculate and update the no-load mode current judgment threshold of the equivalent single-phase section corresponding to the modulus k The threshold setting formula is as follows:

in, is the nodal-mode voltage at node p in the equivalent single-phase segment, is the node mode voltage at node q in the equivalent single-phase section; U _nom is the rated voltage amplitude of the line in the equivalent single-phase section; is the parallel mode admittance per unit length of the line in the equivalent single _- phase section; _L is the length of the line in the equivalent single-phase section; 1.2.

Step 2. Determine the no-load state of the equivalent single-phase section corresponding to the modulus k. Read the node-mode current at the nodes p and q at both ends of the equivalent single-phase section corresponding to the modulus k The magnitude of the current corresponds to Judge according to the following criteria: if any and is established, the equivalent single-phase section is in the no-load operation state, that is, the section is in the no-load operation state; if there is or If it is established, the equivalent single-phase section is in the non-no-load operation state, that is, the section is in the non-no-load operation state.

Step 3, outputting the judgment result.

It can be determined whether a certain section in the distribution network containing distributed If it is no-load operation, then block the fault judgment of the section; if the section is not no-load operation, then do not block the fault judgment of the section.

(2) The differential current detection method applicable to the distribution network section containing distributed power is as follows:

In order to further improve the reliability of fault judgment in a certain section of the distribution network containing distributed power generation and prevent misjudgment, if necessary, during the fault judgment process in this section, the section line After the no-load detection, it is also possible to increase the differential mode current detection of the section, and use the overcurrent of the differential mode current of the section to start the equivalent single-phase section fault judgment method suitable for distribution networks with distributed power sources , to determine whether a fault occurs in the single-phase section to which the modulus is equivalent. Generally, when criterion 1 is adopted in the equivalent single-phase section fault judgment method applicable to the distribution network with distributed generation, or the number of continuous sampling points in criterion 2 is N=1, the section must be increased In other cases, you can choose whether to add this link according to the actual situation and needs.

The definition of the mode current differential flow of the section in the distribution network containing distributed power sources is: in a certain section in the distribution network containing distributed power sources, let the nodes at both ends of the section be node p , q, the node-mode currents at the nodes p and q in the equivalent single-phase section formed by a certain modulus k after phase-mode transformation in this section are respectively Let the positive direction of the current in this section be from node p to node q, then the modulus current differential flow of modulus k in this section can be defined The calculation formula is:

In general, the amplitude of the differential mode current of a section in a distribution network with distributed power generation in normal operation will not exceed the no-load current amplitude of the line in this section. Therefore, the modulus current differential current detection method suitable for the section of the distribution network containing distributed power needs to know the modulus numbered k used for fault judgment in the section, and the equivalent single-phase current corresponding to the modulus k Nodal modulus voltage at nodes p and q at both ends of the segment Nodal mode current The series mode impedance of the line in the equivalent single-phase section under unit length and parallel mode admittance The length L of the line in the section, and the rated voltage amplitude U _nom of the line in the section. The method for detecting the differential current of the molded current includes four steps as follows:

Step 1. Calculate and update the judgment threshold of the modulus current differential current in the equivalent single-phase section corresponding to the modulus k The threshold setting formula is as follows:

in, is the nodal-mode voltage at node p in the equivalent single-phase segment, is the node mode voltage at node q in the equivalent single-phase section; U _nom is the rated voltage amplitude of the line in the equivalent single-phase section; is the parallel mode admittance per unit length of the line in the equivalent single-phase section; _L is the length of the line in the equivalent _single -phase section; 1.3.

Step 2. Calculating the differential modulus current of the equivalent single-phase section corresponding to the modulus k. Read the node-mode current at the nodes p and q at both ends of the equivalent single-phase section corresponding to the modulus k According to the definition of the modulus current differential flow in the section of the distribution network containing distributed power generation, calculate the modulus k of the modulus current differential flow of the section

Step 3. Determine whether the modulus k of the section modulus k is overcurrent, and the criterion is: when the magnitude of the modulus k of the section modulus k greater than the judgment threshold when , then the mode current difference of this section flows through the current; when the mode current difference amplitude of the section modulus k Less than or equal to the decision threshold when , the mode current difference in this section cannot flow.

Step 4, outputting the judgment result.

Using the above method, it is possible to determine whether the modulus current differential current used for fault judgment is overcurrent in the section of the distribution network containing distributed power. If it is overcurrent, the fault judgment of the section will be started. Determine whether a fault occurs in the single-phase section to which the modulus is equivalent; if there is no flow, then block the fault judgment of the section, and do not perform fault judgment in the single-phase section to which the modulus is equivalent.

(3) The equivalent single-phase section fault judgment method applicable to the distribution network with distributed generation is as follows:

Through the fault judgment in the single-phase section equivalent to the selected modulus for section fault judgment, various faults that occur in the actual section can be equivalently judged, such as: single-phase ground short circuit, two-phase Ground short circuit, two-phase phase-to-phase short circuit and three-phase short circuit fault, get the fault judgment result of the section.

If the number of the modulus selected for fault judgment in the section is k, then, in the single-phase section equivalent to the modulus k, a reasonable threshold σ _k of the absolute value of the phase angle difference of the section mode current can be set , to judge whether there is a fault in the equivalent single-phase section, the criterion is as follows:

Criterion 1: When the absolute value of the phase angle difference of the modular current in the equivalent single-phase section is less than or equal to its threshold σ _k , that is When , there is no fault in this section; when the absolute value of the phase angle difference of the modulus current in the equivalent single-phase section greater than its threshold σ _k , that is , a fault occurs in this section.

Criterion 2: In practical applications, in order to reduce the possibility of misoperation of this method and avoid tripping of section lines caused by instantaneous faults, the following improved criterion can be adopted: if the analog current phase of the equivalent single-phase section Absolute value of angular difference greater than its threshold σ _k , that is And when it is true at consecutive N sampling points, it is determined that there is a fault in this section; otherwise, there is no fault in this section. Among them, N≥1, and N∈Z, the value of N can be selected according to the actual situation and needs, the larger the value of N, the lower the sensitivity and the worse the rapidity of section fault judgment; when N=1, the The criterion is equivalent to criterion one.

Among them, the setting of the threshold σ _k of the phase angle difference of the mode current in the equivalent single-phase section is not only related to the absolute value of the phase angle difference of the mode current in the normal operation of the equivalent single-phase section, but also related to the current measurement The phase angle error δ is related to the angle numerical calculation error ε, and the setting formula of the threshold σ _k is:

In the above formula, is the nodal mode voltage at the node p at both ends of the equivalent single-phase section, is the node-mode voltage at node q at both ends of the equivalent single-phase section; is the series mode impedance per unit length of the equivalent single-phase section line, _is the parallel mode admittance per unit length of the line in the equivalent single-phase section; _L is the length of the line in the equivalent single-phase section; .

In general, the selection of the current transformer in the current measuring device will produce a current phase angle measurement error of ±7° under the condition of referring to the 10% error curve of the current transformer, that is, δ=7°; Numerical calculation errors are often small and often negligible. If it is necessary to consider improving the reliability of the method, ε=0.5°～1° can be selected according to the actual situation. (6) Using the fault judgment results of each section in the distribution network containing distributed power, according to the generation and judgment method of the system fault judgment matrix, perform fault judgment and fault location on the distribution network containing distributed power, and Obtain the fault location result at the current moment.

The generation and judgment methods of the system fault judgment matrix are as follows:

Step 1. Read the fault judgment results of each section in the distribution network containing distributed power, and generate the system fault judgment matrix Γ. The system failure judgment matrix Γ is a row matrix, and Γ=[γ ₁ γ ₂ ... γ _h ], where h is the total number of sections in the distribution network containing distributed power; γ _i is the failure state of the i-th section (i=1,...,h), if a failure occurs in the section, then γ _i =1; if there is no failure in the section, then γ _i =0.

Step 2. Make the following further judgments according to the system fault judgment matrix Γ, the criterion is: if the value of all elements in the system fault judgment matrix Γ is 0, then there is no fault in the distribution network containing distributed generation, and it is in the The state of normal operation; if there is one or several elements in the system fault judgment matrix Γ with a value of 1, then there is a fault in the distribution network containing distributed power, and the fault points are in the system fault judgment matrix Γ In the segment corresponding to the element number whose element value is 1.

Step 3. Output the fault location result: if there is no fault in the distribution network containing distributed power, output "normal operation"; if there is a fault in the distribution network containing distributed power, output "system failure", And then output the section numbers where all the fault points are located.

The self-adaptive fault section location method applicable to the distribution network with distributed power sources of the present invention can perform real-time online fault location in the system, and can quickly isolate the fault section when the system fails. The method in the case of a real-time online application comprises the following four steps:

Step 1. According to the section division method and numbering requirements of the distribution network containing distributed Each node and section in the distribution network of the power supply shall be numbered as required.

Step 2. Apply the self-adaptive section fault judgment method applicable to the distribution network containing distributed power to each section in the distribution network containing distributed Whether there is a fault in each section of the distribution network of the conventional power supply, and the judgment result is obtained.

Step 3. Using the fault judgment results of each section in the distribution network containing distributed power sources, according to the generation and judgment method of the system fault judgment matrix, perform fault judgment and fault location on the distribution network containing distributed power sources, and Obtain the fault location result at the current moment.

Step 4. Enter the next moment after the current moment, and return to step 2.

Using the above method, adaptive online fault section location can be realized in the distribution network with distributed power generation. Wherein, in the adaptive section fault determination method applicable to distribution networks containing distributed power sources, it is known that the section is an n-phase section, and the nodes at both ends of the section are nodes p and q, the length of the line in this section is L, the rated voltage amplitude of the line in this section is U _nom , and the series resistance matrix R _(n) and series inductance matrix L _(n) of the line unit length in this section and the parallel capacitance matrix C _(n) , determine whether to enable differential current detection of the mode current in this section according to the actual situation. Then the method includes the following eleven steps:

Step 1. Input the required electrical variables at the current moment. The required electrical variables include: the phase voltage on the line of the section, the fundamental frequency f of the phase current; the n-phase node voltage matrix at the nodes p and q at both ends of the section and n-phase node current matrix

Step 2. Design a phase-mode transformation matrix Φ _(n) ^T that can be used in the n-phase section by using the design method of the phase-mode transformation matrix considering the non-transposition balance of line parameters.

Step 3. Using the phase-mode transformation matrix Φ _(n) ^T , according to the phase-mode transformation formula applicable to the distribution network containing distributed power sources, the n-phase node voltage matrix at the nodes p and q at both ends of the section and n-phase node current matrix Perform phase-to-mode transformation respectively to obtain the mode voltage matrix at nodes p and q at both ends of the section and mode current matrix And calculate the series mode impedance matrix of the unit length of the line in this section with parallel mode admittance matrix

Step 4. Select the number of the modulus used in this section according to the selection rule of the modulus used for fault judgment, and denote it as k. At the same time, based on the selected modulus k, the following required magnitudes are extracted, which are divided into: kth modulus voltage at nodes p, q at both ends of the segment with the kth mode current The series mode impedance of the unit length of the line equivalent to the kth modulus obtained after the phase-mode transformation of this section with parallel mode admittance

Step 5. Using the section line no-load detection method applicable to the distribution network with distributed power sources, determine whether the section is in no-load operation. If the section is in the no-load running state, enter the next moment after the current moment and return to step 1; if the section is in the non-no-load running state, go to step 6.

Step 6, judging whether it is necessary to detect the differential mode current of the section, if yes, go to step 7; if not, go to step 8.

Step 7. Using the differential mode current detection method applicable to the section of the distribution network containing distributed power sources, determine whether the differential mode current corresponding to the modulus k in the section is overcurrent. If the modulus k corresponding to the modulus k in this section does not over-current, enter the next moment after the current moment and return to step 1; , go to step 8.

Step 8. In the single-phase section equivalent to the selected kth modulus, use the kth mode current matrix at the nodes p and q at both ends of the section Obtain the phase angle of the mode current corresponding to the mode current through Fourier transform According to the definition of the current phase angle difference of the section in the distribution network with distributed power generation, the absolute value of the modular current phase angle difference of the equivalent single-phase section is calculated

Step 9. In the single-phase section equivalent to the k-th modulus, use the equivalent single-phase section fault judgment method suitable for distribution networks with distributed power sources, and first set the threshold according to the method proposed The formula updates the judgment threshold in real time, and then uses the absolute value of the phase angle difference of the mode current in the equivalent single-phase section According to the criterion proposed in the method, whether a fault occurs in the equivalent single-phase section is judged, and the judgment result is obtained.

Step 10, use the judgment result obtained in step 9 to make the following judgment: if the judgment result is no fault, then there is no fault inside the section, save the fault judgment result, and then enter the next time after the current time and return to step 1; If the judgment result is that a fault occurs, a fault occurs inside the section, and the next step is entered.

Step 11. Save the fault judgment result, and immediately send out a protection action signal to quickly isolate the faulty section. After the fault is checked and repaired, return to step 1 through manual control.

Utilizing the above-mentioned self-adaptive section fault judgment method applicable to distribution network with distributed generation, it is possible to realize real-time, fast, accurate and reliable intra-section fault detection in any section of distribution network with distributed generation judgment. In view of the fact that the method obtains the corresponding current phase angle from the node current through Fourier transform, and considering that the Fourier transform requires at least one current cycle length initialization time, if the voltage in the distribution network including distributed power, If the current fundamental frequency is f, then the length of initialization time is 1/f. Therefore, after the distribution network with distributed The method is applied in the section to realize the judgment of the faults in the section. In addition, this method can calculate, set and update all the judgment thresholds used in the method in each sampling period, which ensures the adaptability of the method. The sampling frequency of the method should not be lower than 10kHz.

The self-adaptive fault section location method of the distribution network containing distributed power sources in the present invention proposes an adaptive fault section location method based on the phase angle difference of the mode current and applicable to the distribution network containing distributed power sources, Compared with prior art, the beneficial effect that this method can produce is:

First, the present invention can be used for fault location of a distribution network containing distributed power sources, and can accurately and reliably locate faults in a variety of fault situations: single-phase ground short circuit, two-phase ground short circuit, two-phase phase-to-phase short circuit, three-phase short circuit Realize the section location of the fault, and is not affected by various non-fault disturbances, has the setting calculation and real-time update mechanism of the judgment threshold, and has good adaptability;

Second, the fault location method proposed by the present invention is an online fault location method, which can quickly perform fault judgment and fault location in real time during the operation of the distribution network containing distributed power sources, which is beneficial to distribution networks containing distributed power sources Rapid processing and small-scale isolation of faults in the power grid;

Thirdly, the configuration of the fault location method proposed by the present invention is very flexible and versatile, and can simultaneously detect multiple types of sections in a distribution network containing distributed power sources: single-phase sections, two-phase sections , All kinds of faults that occur in the three-phase section are accurately judged and located.

Description of drawings

Fig. 1 is a schematic diagram of the method of the present invention;

Fig. 2 is a schematic structural diagram of an embodiment of a distribution network including a distributed power supply applying the present invention;

Fig. 3 is the working principle diagram of the information processing and data calculation module of the embodiment;

Fig. 4 is the working principle diagram of the fault judgment and protection control module of the embodiment;

Fig. 5 is a working principle diagram of the control center of the embodiment.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is the schematic diagram of the method of the present invention. In a distribution network containing distributed power, under the condition that all line parameters in the distribution network containing distributed The distribution network is divided into multiple double-ended branchless sections, and each node and section in the distribution network containing distributed power is numbered. Then, step 002 is executed to collect information in each section of the distribution network containing distributed power, and step 003 is executed to perform phase-to-mode transformation on the electrical quantity in the section, and convert the coupled electrical quantity in the section into The moduli are independent of each other, and the mode voltage, mode current, series mode impedance and parallel mode admittance of the line unit length corresponding to each modulus are obtained. Then, execute step 004, select the modulus used for judging the fault, carry out no-load detection to the line of the section through step 005, if the line of the section is non-empty load, then enter step 006; if the line of the section is no-load , return to step 002. After entering step 006, the differential mode current detection of the section is performed, and if the differential mode current of the section is overcurrent, then enter step 007; if the differential mode current of the section is not overcurrent, return to step 002. Execute step 007 to obtain the absolute value of the phase angle difference of the modulus corresponding to the selected modulus for segment fault judgment, and execute step 008 to perform fault judgment on the segment, and pass the obtained modulus current The comparison between the absolute value of the phase angle difference and the judgment threshold gives the fault judgment result of the section. Finally, use the fault judgment results of all sections in the distribution network containing distributed power, execute step 009 to generate a system fault judgment matrix, execute step 010 to judge the system fault judgment matrix, obtain the fault location result, and then return Step 002.

Fig. 2 is a schematic structural diagram of an embodiment of a distribution network including distributed power sources to which the present invention is applied. As shown in FIG. 2 , in a distribution network including distributed power sources, distributed power sources 102 and loads 103 are connected to the busbar 101 . In the distributed power distribution network, according to the section division method and numbering requirements of the distributed power distribution network, the distribution network is divided into several double-ended and branchless sections 104, and the section The nodes at both ends of the section 104 are node p105 and node q106 respectively, and a group of measuring elements 107 and circuit breakers 108 are arranged at node p105 and node q106 respectively. Among them, the measuring element 107 can measure the node voltage signal and the node current signal at the node p105 and node q106 in the section 104; the circuit breaker 108 can cut off the fault loop when the section 104 fails, and isolate the failed section 104. Define the positive current direction 109 of the section 104 as pointing from the node p105 to the node q106, then the node p105 can be set as the upstream node, and the node q106 can be the downstream node, and the fault location master device 110 is configured at the upstream node p105, and the downstream node The fault location slave device 111 is configured at q106, and the fault location master device 110 and the fault location slave device 111 are interconnected through optical fiber communication 112, and the fault location master device 110 and the fault location slave device 111 can receive the measurement signal from the measuring element 107, and can A trip signal is sent to the circuit breaker 108 to control the operation of the circuit breaker. The fault location master device 110 includes two parts, the information processing and data calculation module 113 and the fault judgment and protection control module 114 , and the fault location slave device 111 only includes the information processing and data calculation module 113 . The information processing and data calculation module 113 can transform and process the measurement signal collected by the measuring element 107, and obtain the information and value required for fault judgment through calculation, and send the data of these information and value to the fault judgment and protection control module 114; the fault determination and protection control module 114 utilizes the data sent by the information processing and data calculation module 113 in the fault location master device 110 and the fault location slave device 111 to determine whether a fault occurs in the section 104, and The fault judgment result is sent to the control center 115 through the communication link 116. When a fault occurs in the judgment section 104, the fault judgment and protection control module 114 will send a trip signal, which can be transmitted through the fault location main device 110 through the optical fiber The communication 112 is sent to the fault location slave device 111 , and the fault location master device 110 and the fault location slave device 111 are used to control the action of the circuit breaker 108 to complete the isolation of the fault section 104 . The control center 115 interacts with the fault location master devices 110 in all the sections 104 in the distribution network containing distributed power through the communication link 116, and can receive faults sent by the fault location master devices 110 in each section 104 Judgment result, generate a fault judgment matrix, and judge whether each section 104 in the entire distribution network containing distributed On-line fault section location within a power distribution network.

FIG. 3 is a working principle diagram of the information processing and data calculation module 113 of the embodiment. As shown in Figure 3, the working principle of the information processing and data calculation module 113 is as follows: First, the information processing and data calculation module 113 can obtain the voltage and current information 202 of each phase at the node through the information collection 201, and then know the line The number of phases is 204. Using the voltage and current information 202 of each phase at the node, the fundamental frequency 205 of the voltage and current can be obtained through the phase-locked loop PLL 203 . Next, using the phase number 204 of the line, the fundamental frequency 205, the series resistance matrix 206 of the line unit length, the series inductance matrix 207 of the line unit length, and the parallel capacitance matrix 208 of the line unit length, according to the non-transposition balance considering line parameters The design method 209 of the phase-mode transformation matrix can obtain the phase-mode transformation matrix 210 , the series impedance matrix 211 of the unit length of the line, and the parallel admittance matrix 212 of the unit length of the line. Next, using the phase voltage and current information 202 at the node, the phase-to-mode transformation matrix 210, the series impedance matrix 211 of the unit length of the line, and the parallel admittance matrix 212 of the unit length of the line, according to the distribution network with distributed power According to the phase-mode transformation formula 213, the node-mode current matrix 214, the node-mode voltage matrix 215, the series-mode impedance matrix 216 of the line unit length, and the parallel-mode admittance matrix 217 of the line unit length can be obtained. Then, according to the selection rules of the modulus used for fault judgment, the selection 218 of the modulus k used for fault judgment is realized. In the node mode current matrix 214, node mode voltage matrix 215, line unit length series mode impedance matrix 216 and In the parallel mode admittance matrix 217 per unit length of the line, the k-mode current 219 at the node, the k-mode voltage 220 at the node, the series k-mode impedance 221 per unit length of the line, and the parallel k-mode admittance 222 per unit length of the line are selected. Wherein, the k-mode current 219 at the node is subjected to a fast Fourier transform FFT 223 to obtain a phase angle 224 of the k-mode current at the node. Finally, the k-mode current phase angle 224 at the node, the k-mode current 219 at the node, the k-mode voltage 220 at the node, the series k-mode impedance 221 per unit length of the line, and the parallel k-mode admittance 222 per unit length of the line are integrated, Send the data to the fault judgment and protection control module 225 in the fault location master device.

In practical applications, it should be noted that the information processing and data calculation module 113 in a group of fault location master devices 110 and fault location slave devices 111 located in the same section 104 shown in FIG. The technical details of the specific method, for example: the design method 209 of the phase-mode transformation matrix considering the non-transposition balance of line parameters shown in Figure 3, the phase-mode transformation formula 213 applicable to the distribution network with distributed power sources, and the fault judgment used The selection of modulus k, 218, etc., should always be consistent.

Fig. 4 is a working principle diagram of the fault judgment and protection control module 114 of the embodiment. As shown in FIG. 4, the working principle of the fault judgment and protection control module 114 is as follows, including the following twelve processes:

Process 1. The fault judgment and protection control module 114 can define the line length 303 of the section, the rated voltage 304 of the line of the section, and the differential current detection control signal 305 of the section through the initial setting 301. When the value of the current differential current detection control signal 305 is 0, it means that the differential current detection of the segment is not performed; when the value is 1, it indicates that the differential current detection of the segment is required;

Process 2: Receive the data 302 at the current moment, the obtained data includes the k-mode current phase angle 306 at the nodes at both ends of the segment, the k-mode voltage 307 at the nodes at both ends of the segment, and the k-mode current at the nodes at both ends of the segment 308. The series k-mode impedance 309 per line unit length and the parallel k-mode admittance 310 per line unit length, wherein the series k-mode impedance 309 per line unit length and the parallel k-mode admittance 310 per line unit length are from Fig. 1 The data sent by the information processing and data calculation module 113 in the main fault location device 110 to the fault judgment and protection control module 114;

Process 3, the line length 303 of the section, the rated voltage 304 of the line of the section, the mode current differential current detection control signal 305 of the section, the k-mode current phase angle 306 at the nodes at both ends of the section, the node at both ends of the section The k-mode voltage 307 at , the k-mode current 308 at the nodes at both ends of the section, the series k-mode impedance 309 per unit length of the line, and the parallel k-mode admittance 310 per unit length of the line are integrated into data information 311;

Process 4. Use the section line no-load detection method applicable to the distribution network containing distributed power sources to perform no-load detection 312 on the section line, obtain the detection result, and judge whether the section line is in the no-load state 313: if If it is empty, enter process 12; if it is not empty, enter process 5;

Process five: According to the mode current differential current detection control signal 305 of the section in the data information 311, judge whether to perform the k-mode current differential current detection 314 of the section: if the detection is performed, then enter the process six; if not, then Enter process seven;

Process 6. Use the mode current differential current detection method applicable to the section of the distribution network containing distributed power sources to detect the k-mode current differential current of the section 315, obtain the detection result, and judge the k-mode current of the section Whether the differential current is over-current 316: if it is over-current, enter process 7; if not, enter process 12;

Process 7. Carry out the k-mode current phase angle difference calculation 317 of the section, obtain the k-mode current phase angle difference 318 of the section, and use the equivalent single-phase section fault applicable to the distribution network containing distributed power Judgment method, complete the fault judgment 319 of the section, save the judgment result, and send the judgment result to the control center 320;

Process 8. According to the judgment result, determine whether a fault occurs in the section 321: if yes, enter process 9; if not, enter process 12;

Process Nine: Send a protection trip signal to isolate the fault section 323;

Process 10. Set the judgment result as failure and send it to the control center 324;

Process 11. Determine whether a manual reset command is received 325: if yes, return to process 1; if not, return to process 10;

Process twelve, enter the next moment 322, and return to process two.

FIG. 5 is a working principle diagram of the control center 115 of the embodiment. As shown in Fig. 5, the working principle of the control center 115 is as follows, including the following seven processes:

Process 1. Initialization setting 401;

Process 2: Receive the fault determination results of all sections at the current moment 402;

Process 3. Generate a system failure judgment matrix 403 according to the obtained information, and the system failure judgment matrix 404 is a row matrix, wherein each element corresponds to the failure judgment result of a section: when the failure judgment result of the section is normal During operation, the element value corresponding to the system failure judgment matrix 404 is 0; when the failure judgment result of the section is a failure, the element value corresponding to the system failure judgment matrix 404 is 1;

Process 4. In the obtained system fault judgment matrix 404, determine whether all elements in the system fault judgment matrix are 0. 405: if it is 0, then enter process five; if not 0, then enter process six;

Process five, the judgment result is: the distribution network including distributed power supply is running normally 406, the judgment result is output 407, and enters the process seven;

Process 6. The judgment result is: a fault 408 occurs in the distribution network containing distributed power, immediately search for all the elements of 1 in the system fault judgment matrix, save the section number 409 corresponding to these elements, issue a fault indication, and output Fault judgment result and the number 410 of the fault section;

Process seven, enter the next moment, and return to process two.

Claims (9)

1. A method for self-adaptive fault section location of a distribution network containing distributed power sources, characterized in that: first a distribution network containing distributed power sources is segmented, and the distribution network containing distributed The number of each node and section in the power grid; then, collect the voltage and current signals at the nodes at both ends of each section in the distribution network containing distributed power, and use the designed phase-mode transformation matrix to perform Phase-mode transformation converts the coupled electrical quantities in the section into mutually independent moduli, and obtains the corresponding mode voltage, mode current, series mode impedance and parallel mode admittance of the line unit length for each modulus; then, select a Appropriate modulus is used for the judgment of section faults; through section line no-load detection and mode current differential current detection, only when the line in the section is not no-load and the section's mode current difference flows through the current situation Next, the judgment of the section fault is carried out; after entering the section fault judgment process, the absolute value of the mode current phase angle difference of the section corresponding to the modulus selected for section fault judgment is obtained, and the obtained The comparison between the absolute value of the phase angle difference of the model current and the judgment threshold can be used to obtain the fault judgment result of the section; finally, using the fault judgment results of each section in the distribution network containing distributed power generation, according to the generation of the system fault judgment matrix With the judgment method, the fault judgment and fault location are carried out on the distribution network containing distributed power generation, and the fault location result at the current moment is obtained; The design method of described phase mode transformation matrix is: Step 1, obtain the parameter matrix K _(n) of line in the section; The obtaining of K _(n) can be based on the following calculation formula: K _(n) = [R _(n) + j (2πf) L _(n) ] [j (2πf) C _(n) ] Among them, j ² =-1; Step 2, calculate the matrix of the line parameter transposition balance corresponding to the line parameter matrix K _(n) matrix The calculation method is as follows: like Among them, n is the phase number of the line in the section; K _(n) is a symmetrical matrix, and κ _ij = κ _ji is established, i=1,...,n, j=1,...,n, and i≠j ; then there is where α and β respectively satisfy the following formulas: <mrow><mi>&amp;alpha;</mi><mo>=</mo><mfrac><mn>1</mn><mi>n</mi></mfrac><mo>&amp;CenterDot;</mo><munderover><mo>&amp;Sigma;</mo><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover><msub><mi>&amp;kappa;</mi><mrow><mi>i</mi><mi>i</mi></mrow></msub></mrow> <mrow><mi>&amp;beta;</mi><mo>=</mo><mfrac><mn>1</mn><mrow><mi>n</mi><mrow><mo>(</mo><mi>n</mi><mo>-</mo><mn>1</mn><mo>)</mo></mrow></mrow></mfrac><mo>&amp;CenterDot;</mo><mo>&amp;lsqb;</mo><munderover><mo>&amp;Sigma;</mo><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover><mrow><mo>(</mo><munderover><mo>&amp;Sigma;</mo><mrow><mi>j</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover><msub><mi>&amp;kappa;</mi><mrow><mi>i</mi><mi>j</mi></mrow></msub><mo>)</mo></mrow><mo>-</mo><mi>n</mi><mo>&amp;CenterDot;</mo><mi>&amp;alpha;</mi><mo>&amp;rsqb;</mo></mrow> Step 3. Design Matrix the matrix Written in the form shown below: Among them, a _ij is the element in the matrix, and a _ij = a _ji is established, i=1,...,n, j=1,...,n, and i≠j; A is the coefficient of the matrix, and there is According to the phase number n of the section, the matrix is arranged according to the three constraint rules as shown below The value of each element in the design: ① When n=1, that is, the section is a single-phase section, The elements in should satisfy the constraints described in the following formula: a ₁₁ =1 ②When n=2, that is, the section is a two-phase section, The elements in should satisfy the constraints described in the following formula: <mfenced open = "{" close = ""><mtable><mtr><mtd><msub><mi>a</mi><mn>11</mn></msub><mo>=</mo><msub><mi>a</mi><mn>21</mn></msub><mo>&amp;NotEqual;</mo><mn>0</mn></mtd></mtr><mtr><mtd><msub><mi>a</mi><mn>12</mn></msub><mo>+</mo><msub><mi>a</mi><mn>22</mn></msub><mo>=</mo><mn>0</mn></mtd></mtr></mtable></mfenced> ③When n=3, that is, the section is a three-phase section, The elements in should satisfy the constraints described in the following formula: <mfenced open = "{" close = ""><mtable><mtr><mtd><mrow><msub><mi>a</mi><mn>11</mn></msub><mo>=</mo><msub><mi>a</mi><mn>21</mn></msub><mo>=</mo><msub><mi>a</mi><mn>31</mn></msub><mo>&amp;NotEqual;</mo><mn>0</mn></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>a</mi><mn>12</mn></msub><mo>+</mo><msub><mi>a</mi><mn>22</mn></msub><mo>+</mo><msub><mi>a</mi><mn>32</mn></msub><mo>=</mo><mn>0</mn></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>a</mi><mn>13</mn></msub><mo>+</mo><msub><mi>a</mi><mn>23</mn></msub><mo>+</mo><msub><mi>a</mi><mn>33</mn></msub><mo>=</mo><mn>0</mn></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>a</mi><mn>22</mn></msub><mo>&amp;NotEqual;</mo><mn>0</mn><mo>,</mo><msub><mi>a</mi><mn>23</mn></msub><mo>=</mo><msub><mi>a</mi><mn>32</mn></msub><mo>&amp;NotEqual;</mo><mn>0</mn><mo>,</mo><msub><mi>a</mi><mn>33</mn></msub><mo>&amp;NotEqual;</mo><mn>0</mn></mrow></mtd></mtr><mtr><mtd><mrow><msub><mi>a</mi><mn>22</mn></msub><mo>&amp;NotEqual;</mo><msub><mi>a</mi><mn>32</mn></msub><mo>,</mo><msub><mi>a</mi><mn>23</mn></msub><mo>&amp;NotEqual;</mo><msub><mi>a</mi><mn>33</mn></msub></mrow></mtd></mtr></mtable></mfenced> Step 4. Calculate the matrix The eigenvalue matrix of matrix The eigenvalue matrix of can be calculated according to the following formula: <mrow><msubsup><mi>&amp;lambda;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>*</mo></msubsup><mo>=</mo><msup><msubsup><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>*</mo></msubsup><mrow><mo>-</mo><mn>1</mn></mrow></msup><mo>&amp;CenterDot;</mo><msubsup><mi>K</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>*</mo></msubsup><mo>&amp;CenterDot;</mo><msubsup><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>*</mo></msubsup><mo>=</mo><mi>d</mi><mi>i</mi><mi>a</mi><mi>g</mi><mrow><mo>(</mo><msubsup><mi>&amp;lambda;</mi><mn>11</mn><mo>*</mo></msubsup><mo>,</mo><mo>...</mo><mo>,</mo><msubsup><mi>&amp;lambda;</mi><mrow><mi>n</mi><mi>n</mi></mrow><mo>*</mo></msubsup><mo>)</mo></mrow></mrow> Step 5. Use the matrix and matrix K _(n) , computing the matrix matrix The calculation formula is: Step 6, calculating the first-order disturbance matrix W _(n) ; First order perturbation matrix Among them, w _ij is the element in the matrix W _(n) , i=1,...,n, j=1,...,n, and satisfy the following conditions: <mrow><msub><mi>w</mi><mrow><mi>i</mi><mi>j</mi></mrow></msub><mo>=</mo>< mfenced open = "{" close = ""><mtable><mtr><mtd><mn>0</mn></mtd><mtd><mrow><msubsup><mi>&amp;lambda;</mi><mrow><mi>i</mi><mi>i</mi></mrow><mo>*</mo></msubsup><mo>=</mo><msubsup><mi>&amp;lambda;</mi><mrow><mi>j</mi><mi>j</mi></mrow><mo>*</mo></msubsup></mrow></mtd></mtr><mtr><mtd><mrow><mo>-</mo><mfrac><msub><mover><mi>&amp;kappa;</mi><mo>~</mo></mover><mrow><mi>i</mi><mi>j</mi></mrow></msub><mrow><msubsup><mi>&amp;lambda;</mi><mrow><mi>i</mi><mi>i</mi></mrow><mo>*</mo></msubsup><mo>-</mo><msubsup><mi>&amp;lambda;</mi><mrow><mi>j</mi><mi>j</mi></mrow><mo>*</mo></msubsup></mrow></mfrac></mrow></mtd><mtd><mrow><msubsup><mi>&amp;lambda;</mi><mrow><mi>i</mi><mi>i</mi></mrow><mo>*</mo></msubsup><mo>&amp;NotEqual;</mo><msubsup><mi>&amp;lambda;</mi><mrow><mi>j</mi><mi>j</mi></mrow><mo>*</mo></msubsup></mrow></mtd></mtr></mtable></mfenced></mrow> Step 7, the transformation matrix Φ _(n) of calculation matrix K _(n) ; The transformation matrix Φ _{(n) of calculation matrix K ( n)} can be based on the following calculation formula: <mrow><msub><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>=</mo><msubsup><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>*</mo></msubsup><mo>+</mo><msubsup><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>*</mo></msubsup><mo>&amp;CenterDot;</mo><msub><mi>W</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>=</mo><msubsup><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow><mo>*</mo></msubsup><mo>&amp;CenterDot;</mo><mrow><mo>(</mo><msub><mi>E</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>+</mo><msub><mi>W</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>)</mo></mrow></mrow> Wherein, E _(n) is an n-order identity matrix; Step 8, carry out Schmidt diagonalization process to transformation matrix Φ _(n) , after matrix transposition, can finally obtain required phase-mode transformation matrix Φ _(n) ^T ; In the design method of the phase-to-mode transformation matrix, it is necessary to know the phase number n in the section, the fundamental frequency f of the voltage and current phasors, the series resistance matrix R _(n) of the line unit length in the section, and the unit is Ω/km, the series inductance matrix L _(n) , the unit is H/km, and the parallel capacitance matrix C _(n) , the unit is F/km, their mathematical expressions are respectively: Among them, r _ij represents the series self-resistance of the line unit length in this section, i=j; r _ij represents the series mutual resistance of the line unit length in this section, i≠j; l _ij represents the line unit length in this section The series self-inductance of the line, i=j; l _ij represents the series mutual inductance of the line unit length in this section, i≠j; c _ij represents the parallel self-capacitance of the line unit length in this section, i=j; c _ij represents the Parallel mutual capacitance of line unit length in the section, i≠j. 2. According to the self-adaptive fault section location method according to claim 1, it is characterized in that: the described method for segmenting the distribution network containing distributed power is: in a power distribution network containing distributed power The network is divided into several double-ended branchless sections, each section has only two end nodes, and the section has no other branch roads between the two end nodes; Individual node and segment numbers within the grid. 3. according to the described self-adaptive fault zone localization method of claim 1, it is characterized in that, described utilize phase-mode transformation matrix, section is carried out phase-mode transformation, the electrical quantity of coupling in the section is converted into mutually independent mode Quantitative methods are: Let the node voltage matrix at any node in a certain n-phase section in the distribution network containing distributed power generation be U _(n) and the node current matrix be I _(n) , the series impedance of the unit length of the line where the node is located The matrix is Z _(n) , and the parallel admittance matrix per unit length of the line where the node is located is Y _(n) , where: <mrow><msub><mi>U</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>=</mo><mfenced open = "[" close = "]"><mtable><mtr><mtd><msub><mi>U</mi><mn>1</mn></msub></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><msub><mi>U</mi><mi>n</mi></msub></mtd></mtr></mtable></mfenced></mrow> <mrow><msub><mi>I</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>=</mo><mfenced open = "[" close = "]"><mtable><mtr><mtd><msub><mi>I</mi><mn>1</mn></msub></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><mo>.</mo></mtd></mtr><mtr><mtd><msub><mi>I</mi><mi>n</mi></msub></mtd></mtr></mtable></mfenced></mrow> Then there is the following phase-mode transformation formula, which can realize the decoupling of electrical quantities and line parameters in this section: <mrow><msub><mover><mi>U</mi><mo>&amp;OverBar;</mo></mover><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>=</mo><msup><msub><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mi>T</mi></msup><mo>&amp;CenterDot;</mo><msub><mi>U</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub></mrow> <mrow><msub><mover><mi>I</mi><mo>&amp;OverBar;</mo></mover><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>=</mo><msup><msub><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mi>T</mi></msup><mo>&amp;CenterDot;</mo><msub><mi>I</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub></mrow> <mrow><msub><mover><mi>Z</mi><mo>&amp;OverBar;</mo></mover><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>=</mo><msup><msub><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mi>T</mi></msup><mo>&amp;CenterDot;</mo><msub><mi>Z</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>&amp;CenterDot;</mo><msub><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub></mrow> <mrow><msub><mover><mi>Y</mi><mo>&amp;OverBar;</mo></mover><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>=</mo><msup><msub><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mi>T</mi></msup><mo>&amp;CenterDot;</mo><msub><mi>Y</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub><mo>&amp;CenterDot;</mo><msub><mi>&amp;Phi;</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></msub></mrow> in, is the node-mode voltage matrix obtained through phase-mode transformation; is the node-mode current matrix obtained through phase-mode transformation; is the series-mode impedance matrix of the unit length of the line in the section obtained through phase-mode transformation; is the parallel mode admittance matrix of the line unit length in the section obtained by phase-mode transformation. 4. according to the self-adaptive fault section localization method described in claim 1, it is characterized in that, the method for the modulus that described selection is used for section fault judgment is as follows: Among the n mutually independent electrical moduli obtained through phase-mode transformation, a specific modulus is selected so that the actual phase angle difference of the modulus in the single-phase section equivalent to the modulus can be used to determine the actual Various types of faults that occur in the n-phase section: single-phase ground short circuit, two-phase ground short circuit, two-phase phase-to-phase short circuit, three-phase short circuit; select the modulus used for fault judgment according to the following empirical rules: ①When n=1, that is, the section is a single-phase section, and the phase-mode transformation matrix contains only one row of elements, an equivalent modulus can be obtained after phase-mode transformation, and this modulus is selected as the mode used for fault judgment quantity; ②When n=2, that is, the section is a two-phase section, the phase-mode transformation matrix contains two rows of elements, and two equivalent moduli are obtained after the phase-mode transformation, and the two moduli are respectively ordered according to the row labels are modulus 1 and modulus 2, and modulus 1 is preferred as the modulus used for fault judgment; ③When n=3, that is, the section is a three-phase section, and the phase-mode transformation matrix contains three rows of elements, and three equivalent moduli are obtained after the phase-mode transformation, and these three moduli can be made according to the row labels They are modulus 1, modulus 2, and modulus 3 respectively. Choose a modulus between modulus 2 and modulus 3 as the modulus used for fault judgment. If there is no special requirement, modulus 2 is preferred. 5. according to the self-adaptive fault section localization method described in claim 1, it is characterized in that, described section line no-load detection method is as follows: Step 1. Calculate and update the no-load mode current judgment threshold of the equivalent single-phase section corresponding to the modulus k The threshold setting formula is as follows: <mrow><msub><mover><mi>I</mi><mo>&amp;OverBar;</mo></mover><mrow><mn>0</mn><mi>k</mi></mrow></msub><mo>=</mo><msub><mi>&amp;eta;</mi><mrow><mn>0</mn><mi>k</mi></mrow></msub><mo>&amp;CenterDot;</mo><mi>m</mi><mi>a</mi><mi>x</mi><mrow><mo>(</mo><mo>|</mo><msubsup><mover><mi>U</mi><mo>&amp;OverBar;</mo></mover><mi>k</mi><mi>p</mi></msubsup><mo>|</mo><mo>,</mo><mo>|</mo><msubsup><mover><mi>U</mi><mo>&amp;OverBar;</mo></mover><mi>k</mi><mi>q</mi></msubsup><mo>|</mo><mo>,</mo><msub><mi>U</mi><mrow><mi>n</mi><mi>o</mi><mi>m</mi></mrow></msub><mo>)</mo></mrow><mo>&amp;CenterDot;</mo><mo>|</mo><msub><mover><mi>y</mi><mo>&amp;OverBar;</mo>mo></mover><mrow><mi>k</mi><mi>k</mi></mrow></msub><mo>|</mo><mo>&amp;CenterDot;</mo><mi>L</mi></mrow> in, is the nodal-mode voltage at node p in the equivalent single-phase segment, is the node mode voltage at node q in the equivalent single-phase section; U _nom is the rated voltage amplitude of the line in the equivalent single-phase section; is the parallel mode admittance per unit length of the line in the equivalent single _- phase section; _L is the length of the line in the equivalent single-phase section; 1.2; Step 2. Determine the no-load state of the equivalent single-phase section corresponding to the modulus k; read the node mode current at the nodes p and q at both ends of the equivalent single-phase section corresponding to the modulus k The magnitude of the current corresponds to Judge according to the following criteria: if any and is established, the equivalent single-phase section is in the no-load operation state, that is, the section is in the no-load operation state; if there is or is established, the equivalent single-phase section is in a non-no-load operating state, that is, the section is in a non-no-load operating state; Step 3, output the judgment result; In the line no-load detection method of the section, it is necessary to know the modulus number k selected for fault judgment in the section, and the nodes p and q at both ends of the equivalent single-phase section corresponding to the modulus k The node-mode voltage of Nodal mode current The series mode impedance of the unit length of the line in the equivalent single-phase section and parallel mode admittance The length L of the line in the section, and the rated voltage amplitude U _nom of the line in the section. 6. according to the self-adaptive fault zone localization method described in claim 1, it is characterized in that, the mode current differential current detection method of described zone is as follows: Step 1. Calculate and update the judgment threshold of the modulus current differential current in the equivalent single-phase section corresponding to the modulus k The threshold setting formula is as follows: <mrow><msub><mover><mi>I</mi><mo>&amp;OverBar;</mo></mover><mrow><mi>d</mi><mi>k</mi></mrow></msub><mo>=</mo><msub><mi>&amp;eta;</mi><mrow><mi>d</mi><mi>k</mi></mrow></msub><mo>&amp;CenterDot;</mo><mi>m</mi><mi>a</mi><mi>x</mi><mrow><mo>(</mo><mo>|</mo><msubsup><mover><mi>U</mi><mo>&amp;OverBar;</mo></mover><mi>k</mi><mi>p</mi></msubsup><mo>|</mo><mo>,</mo><mo>|</mo><msubsup><mover><mi>U</mi><mo>&amp;OverBar;</mo></mover><mi>k</mi><mi>q</mi></msubsup><mo>|</mo><mo>,</mo><msub><mi>U</mi><mrow><mi>n</mi><mi>o</mi><mi>m</mi></mrow></msub><mo>)</mo></mrow><mo>&amp;CenterDot;</mo><mo>|</mo><msub><mover><mi>y</mi><mo>&amp;OverBar;</mo>mo></mover><mrow><mi>k</mi><mi>k</mi></mrow></msub><mo>|</mo><mo>&amp;CenterDot;</mo><mi>L</mi></mrow> in, is the nodal-mode voltage at node p in the equivalent single-phase segment, is the node mode voltage at node q in the equivalent single-phase section; U _nom is the rated voltage amplitude of the line in the equivalent single-phase section; is the parallel mode admittance per unit length of the line in the equivalent single-phase section; _L is the length of the line in the equivalent _single -phase section; 1.3; Step 2. Calculate the mode current differential current of the equivalent single-phase section corresponding to the modulus k; read the node mode current at the nodes p and q at both ends of the equivalent single-phase section corresponding to the modulus k According to the definition of the modulus current differential flow in the section of the distribution network containing distributed power generation, calculate the modulus k of the modulus current differential flow of the section Step 3. Determine whether the modulus k of the section modulus k is overcurrent, and the criterion is: when the magnitude of the modulus k of the section modulus k greater than the judgment threshold when , then the mode current difference of this section flows through the current; when the mode current difference amplitude of the section modulus k Less than or equal to the decision threshold when , the mode current difference in this section does not flow; Step 4, output the judgment result; In the mode current differential current detection method of the section, it is necessary to know the modulus numbered k selected for fault judgment in the section, and the corresponding nodes p, p, Nodal modulo voltage at q Nodal mode current The series mode impedance of the line in the equivalent single-phase section under unit length and parallel mode admittance The length L of the line in the section, and the rated voltage amplitude U _nom of the line in the section. 7. adaptive fault section localization method according to claim 6, is characterized in that, the definition of the mode current difference flow of described section is: In a section of the distribution network containing distributed power, let the nodes at both ends of the section be nodes p and q respectively, and the equivalent modulus k formed by a certain modulus k after phase-mode transformation in this section The node-mode currents at the nodes p and q at both ends of the single-phase section are respectively Let the positive direction of the current in this section be from node p to node q, then define the modulus current differential flow of modulus k in this section The calculation formula is: 8. The self-adaptive fault section location method according to claim 1, characterized in that, the section fault judgment method is: If the number of the modulus selected for fault judgment in the section is k, then, in the single-phase section equivalent to the modulus k, by setting a reasonable threshold σ _k of the absolute value of the phase angle difference of the section mode current, In order to judge whether there is a fault in the equivalent single-phase section, and then can equivalently determine various types of faults that occur in the actual section, and obtain the fault judgment result of the section, the criterion is as follows: Criterion 1: When the absolute value of the phase angle difference of the modular current in the equivalent single-phase section is less than or equal to its threshold σ _k , that is When , there is no fault in this section; when the absolute value of the phase angle difference of the modulus current in the equivalent single-phase section greater than its threshold σ _k , that is , a fault occurs in this section; Criterion 2: In practical applications, in order to reduce the possibility of misoperation of this method and avoid tripping of section lines caused by instantaneous faults, the following improved criterion is adopted: if the phase angle of the analog current of the equivalent single-phase section absolute value of difference greater than its threshold σ _k , that is And when it is true at consecutive N sampling points, it is determined that there is a fault in this section; otherwise, there is no fault in this section; where N≥1, and N∈Z, the value of N depends on the actual situation and needs Selection, the larger the value of N, the lower the sensitivity and rapidity of section fault judgment; when N=1, this criterion is equivalent to criterion one; Among them, the setting of the threshold σ _k of the phase angle difference of the mode current in the equivalent single-phase section is not only related to the absolute value of the phase angle difference of the mode current in the normal operation of the equivalent single-phase section, but also related to the current measurement The phase angle error δ is related to the angle numerical calculation error ε, and the setting formula of the threshold σ _k is: <mrow><msub><mi>&amp;sigma;</mi><mi>k</mi></msub><mo>=</mo><msub><mi>&amp;eta;</mi><mrow><mi>S</mi><mi>k</mi></mrow></msub><mo>&amp;CenterDot;</mo><mo>&amp;lsqb;</mo><mo>|</mo><mi>arctan</mi><mrow><mo>(</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><mo>&amp;CenterDot;</mo><mfrac><mrow><mo>|</mo><msubsup><mover><mi>U</mi><mo>&amp;OverBar;</mo></mover><mi>k</mi><mi>p</mi></msubsup><mo>|</mo><mo>+</mo><mo>|</mo><msubsup><mover><mi>U</mi><mo>&amp;OverBar;</mo></mover><mi>k</mi><mi>q</mi></msubsup><mo>|</mo></mrow><mrow><mo>|</mo><msubsup><mover><mi>U</mi><mo>&amp;OverBar;</mo></mover><mi>k</mi><mi>p</mi></msubsup><mo>|</mo><mo>-</mo><mo>|</mo><msubsup><mover><mi>U</mi><mo>&amp;OverBar;</mo></mover><mi>k</mi><mi>q</mi></msubsup><mo>|</mo></mrow></mfrac><mo>&amp;CenterDot;</mo><mo>|</mo><msub><mover><mi>z</mi><mo>&amp;OverBar;</mo>mo></mover><mrow><mi>k</mi><mi>k</mi></mrow></msub><mo>|</mo><mo>&amp;CenterDot;</mo><mo>|</mo><msub><mover><mi>y</mi><mo>&amp;OverBar;</mo></mover><mrow><mi>k</mi><mi>k</mi></mrow></msub><mo>|</mo><mo>&amp;CenterDot;</mo><msup><mi>L</mi><mn>2</mn></msup><mo>)</mo></mrow><mo>|</mo><mo>+</mo><mn>2</mn><mo>&amp;CenterDot;</mo>mo><mrow><mo>(</mo><mi>&amp;delta;</mi><mo>+</mo><mi>&amp;epsiv;</mi><mo>)</mo></mrow><mo>&amp;rsqb;</mo></mrow> In the above formula, is the nodal mode voltage at the node p at both ends of the equivalent single-phase section, is the node-mode voltage at node q at both ends of the equivalent single-phase section; is the series mode impedance per unit length of the equivalent single-phase section line, _is the parallel mode admittance per unit length of the line in the equivalent single-phase section; _L is the length of the line in the equivalent single-phase section; ; The definition of the mode current phase angle difference of the section is: For a section in the distribution network containing distributed power generation, let the node numbers at both ends of the section be p and q respectively, then the module current phases corresponding to the module currents I _p and I _{q at nodes p and q} The angles are θ _p and θ _q respectively, if the specified positive direction of the mode current in the section is from node p to node q, then the phase angle difference of the mode current in the section can be defined as The difference between the phase angle values of the mode current, and has a definition formula: Δθ=θ _p -θ _q , where Δθ is the phase angle difference value of the mode current in the segment between nodes p and q. 9. The self-adaptive fault section location method according to claim 1, characterized in that, the generation and determination method of the system fault judgment matrix are as follows: Step 1. Read the fault judgment results of each section in the distribution network containing distributed power, and generate a system fault judgment matrix Γ; the system fault judgment matrix Γ is a row matrix, and Γ=[γ ₁ γ ₂ … γ _h ], where h is the total number of sections in the distribution network containing distributed generation; γ _i is the fault state of the i-th section (i=1,...,h), if the If a fault occurs inside the section, then γ _i =1; if there is no fault inside the section, then γ _i =0; Step 2. Make the following further judgments according to the system fault judgment matrix Γ, the criterion is: if the value of all elements in the system fault judgment matrix Γ is 0, then there is no fault in the distribution network containing distributed generation, and it is in the The state of normal operation; if there is one or several elements in the system fault judgment matrix Γ with a value of 1, then there is a fault in the distribution network containing distributed power, and the fault points are in the system fault judgment matrix Γ In the segment corresponding to the element number whose element value is 1; Step 3. Output the fault location result: if there is no fault in the distribution network containing distributed power, output "normal operation"; if there is a fault in the distribution network containing distributed power, output "system failure", And then output the section numbers where all the fault points are located.