A method and application of locating high-resistance grounding fault in distribution network based on improved single-ended impedance method

Abstract

The present invention discloses a method and application for locating a high-resistance grounding fault in a distribution network based on an improved single-ended impedance method. The method comprises: 1. using a fast Fourier algorithm to obtain fundamental voltage and current data before and after the fault, using a Π-type line model to equalize the distribution network line, and processing the distribution network by sections; 2. improving the single-ended impedance method, establishing a fault location equation based on the transition resistance consuming zero reactive power; 3. quantitatively analyzing the contribution of DG to the fault current, and using the Thevenin theorem to calculate the equivalent impedance of the network downstream of the fault; 4. executing an iterative algorithm for all sections of the distribution network, and outputting the fault distance and section number to realize the fault location function. The present invention can locate the high-resistance grounding fault in the distribution network, thereby assisting maintenance personnel in quickly checking and troubleshooting the fault, and improving the power supply reliability of the distribution network.

Description

Technical Field

[0001] The invention belongs to the field of electric power systems, and in particular to a method and application for locating a high-resistance grounding fault in a distribution network based on an improved single-ended impedance method. Background Art

[0002] The efficient and stable operation of the distribution network is the key to ensure reliable power supply quality for users. According to statistics, about 80% of user production interruptions are caused by faults in the distribution network. Therefore, a fast and effective fault location method can greatly improve the power supply reliability of the distribution system. In modern distribution networks, distribution lines are distributed in dense cities and vast rural areas. The complex structure makes data monitoring difficult, and only limited monitoring devices are installed.

[0003] The mainstream distribution network fault location methods today can be divided into the following categories: traveling wave method, machine learning-based method and impedance-based method. The traveling wave method uses the refraction and reflection characteristics of the traveling wave signal at the fault point to achieve positioning, and has a high positioning accuracy. In order to accurately detect the arrival time of the traveling wave signal, wavelet transform is often used to process transient signals, but it is difficult to select a suitable mother wavelet and decomposition scale. For weak transient signals, the performance of the traveling wave method is difficult to be satisfactory, especially in the case of noise interference. The traveling wave method requires high sampling rate equipment for positioning, which is difficult to meet in the distribution network. The propagation of traveling waves in the distribution network is affected by its structure, which will cause greater attenuation and distortion, and it is more suitable for transmission systems. The machine learning-based method uses a positioning module to locate the fault, which is very convenient and fast. Its positioning accuracy is also very high. However, it cannot be performed using only recorded data. The positioning module requires a large amount of historical data for training, which limits the application of machine learning-based methods in practice. The impedance-based method only requires the voltage and current information of the fundamental frequency and network parameters. It is low-cost and easy to implement. It is the most widely used method in practical applications.

[0004] The impedance method can be divided into the single-ended impedance method and the double-ended impedance method. The double-ended impedance method has a higher positioning accuracy, but requires synchronous sampling of information on both sides of the fault. The single-ended impedance method only requires measurement information and network parameters of the main substation, which is easier to obtain in the actual distribution network, making the single-ended impedance method more widely used. However, it is affected by the fault resistance, especially the positioning accuracy of high-resistance single-phase grounding faults is greatly affected by it. Summary of the invention

[0005] The present invention aims to solve the deficiencies of the above-mentioned prior art and proposes a distribution network high-resistance grounding fault locating method and application based on an improved single-ended impedance method, in order to locate the distribution network high-resistance grounding fault, thereby assisting maintenance personnel to quickly check and eliminate the fault and improve the power supply reliability of the distribution network.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme:

[0007] The invention discloses a method for locating a high-resistance grounding fault in a distribution network based on an improved single-ended impedance method, which comprises the following steps:

[0008] Step 1: Obtain the synchronously measured voltage and current signals of the main substation monitoring point and the distributed generation DG access node before and after the distribution network fails, and use the fast Fourier algorithm to obtain the three-phase voltage phasor [V abc ]'1 and three-phase current phasor [I abc ]'1. Three-phase voltage phase quantity after fault [V abc ]1 and three-phase current phasor [I abc ]1 and the three-phase current phasors of the hth DG access node after the fault occurs And three-phase voltage phasors

[0009] Step 2: Use the Π-type line model to make the distribution network equivalent. At the node with parallel branches, divide the distribution network into K sections and number each section. Let k represent the number of any section, k∈K; when k=1, the line head end of the kth section is the monitoring point of the main substation of the distribution network;

[0010] Step 3: Use equations (1) and (2) to obtain the three-phase voltage phasor [V abc ]' k+1 and the three-phase current phasor at the line head end [I abc ]' k+1 ; The three-phase voltage phasor at the head end of the line in the k+1th section after the fault occurs [V abc ] k+1 and the three-phase current phasor at the line head end [I abc ] k+1 :

[0011]

[0012]

[0013] In formula (1)-formula (2), [V abc ]' k represents the three-phase voltage phasor at the head end of the line at the kth section before the fault occurs, [I abc ]' k represents the three-phase current phasor at the head end of the line at the kth section before the fault occurs; [V abc ] k It represents the three-phase voltage phasor at the head end of the line at the kth section after the fault occurs, [Iabc ] k represents the three-phase current phasor at the head end of the line in the kth section after the fault occurs; [a] k , [b] k , [c] k , [d] k are all third-order line matrices of the kth section, and have:

[0014]

[0015] b] k =L k [z abc ] (4)

[0016]

[0017] In formula (3) to formula (5), [z abc ]、[y abc ] are the unit line impedance matrix and unit ground admittance matrix of the three-phase line of the distribution network respectively; E is the third-order unit matrix; L k is the line length of the kth section;

[0018] Step 3: Use equation (6) to obtain the initial fault current [I abc ] f,k :

[0019] [I abc ] f,k =[I abc ] k -[I abc ]′ k (6)

[0020] Step 4: Based on the transition resistance consuming zero reactive power, the positioning equation of the kth section is established using equation (7):

[0021]

[0022] In formula (7), x k represents the length of the line between the head end of the kth section and the fault point, that is, the fault distance of the kth section; α2 represents the quadratic coefficient, α1 represents the linear coefficient, α0 represents the constant term, and:

[0023]

[0024]

[0025]

[0026] In formula (8) to formula (10), Im{} is the imaginary part extraction symbol; Re{} is the real part extraction symbol; [] T is the transpose of the matrix;

[0027] Step 5: Execute the iterative algorithm:

[0028] Step 5.1: Define and initialize the number of iterations i = 1; initialize k = 1; set the initial fault current [I abc ] f,k As the fault current of the kth section at the i-th iteration

[0029] Step 5.2: Substitute the fault current of the kth section at the i-th iteration into Substituting into the location equation of the kth section, we get the fault distance of the kth section at the i-th iteration:

[0030] Step 5.3: Judgement Is it true? If so, jump to step 5.5. Otherwise, assign k+1 to k and jump to step 5.4:

[0031] Step 5.4: Determine whether k≤K holds. If so, jump to step 5.2; otherwise, end the iterative algorithm and jump to step 6;

[0032] Step 5.5: Judgement Is it true? If true, store the segment number k and the fault distance After assigning k+1 to k, jump to step 5.4; otherwise, assign i+1 to i, jump to step 5.6; where, is the fault distance of the kth segment at the i-1th iteration. When i=1, let ε is a positive number;

[0033] Step 5.6: Considering the contribution of DG to the fault current, calculate the magnitude of the fault current in the upstream and downstream networks of the fault point in the distribution network with or without DG:

[0034] Step 5.6.1: When the upstream network of the fault point does not contain DG, use equation (11) to obtain the upstream fault current of the kth section at the i-th iteration:

[0035]

[0036] In formula (11), N is the number of load branches between the head end and the fault point of the kth section at the i-th iteration; is the shunt current of the jth load branch, obtained by the forward-backward substitution power flow algorithm; represents the shunt current of the distributed capacitance of the line between the line headend and the fault point in the kth section in the i-th iteration, and is estimated using equation (12):

[0037]

[0038] Step 5.6.2: When the upstream network of the fault point contains DG, use equation (13) to obtain the upstream fault current of the kth section at the i-th iteration:

[0039]

[0040] In formula (13), M is the number of DGs in the upstream network of the fault point; is the line capacitance shunt current between the hth distributed generation and the kth section at the fault point of the i-th iteration, and is obtained using formula (14):

[0041]

[0042] Step 5.6.3: When the downstream network of the fault point does not contain DG, use equation (15) to obtain the downstream fault current of the kth section at the i-th iteration:

[0043]

[0044] In formula (15), is the fault point voltage of the kth section at the i-th iteration and is calculated using formula (16); [Z abc ] thqf,k is the equivalent impedance of the downstream network of the kth section at the fault point in the i-th iteration, calculated using equation (17);

[0045]

[0046]

[0047] In formula (17), [Z abc ] thq,k is the equivalent impedance of the network downstream of the end node of the kth segment; is the line admittance matrix of the kth section between the fault point at the ith iteration and the end of the kth section; is the line impedance matrix between the fault point of the kth section at the ith iteration and the end of the kth section;

[0048] Step 5.6.4: When the downstream network of the fault point contains DG, use equation (18) to obtain the downstream fault current of the kth section at the i-th iteration:

[0049]

[0050] In formula (18), M1 is the number of distributed generation in the downstream network of the fault point in the kth section at the i-th iteration, and N1 is the number of load branches between the h-th distributed generation and the fault point in the downstream network of the fault point in the kth section at the i-th iteration; is the shunt current of the jth load branch between the hth distributed generation and the fault point in the downstream network of the fault point in the kth section at the i-th iteration;

[0051] Step 5.7: Based on Kirchhoff's current law, use equation (19) to obtain the fault current of the kth section at the i-th iteration:

[0052]

[0053] Step 5.8: Substitute the fault current of the kth section estimated in step 5.5 at the i-th iteration into Substituting into equation (7), the positive real number solution is the fault distance of the kth section at the i+1th iteration: make And jump to step 5.3;

[0054] Step 6: Use formula (20) to obtain the fault distance x from the main substation of the distribution network to the fault point total :

[0055]

[0056] In formula (20), K1 is the number set of line sections between the fault section number k and the main substation of the distribution network.

[0057] The present invention discloses an electronic device, comprising a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the method for locating a high-resistance grounding fault in a distribution network, and the processor is configured to execute the program stored in the memory.

[0058] The present invention provides a computer-readable storage medium on which a computer program is stored. The computer-readable storage medium is characterized in that when the computer program is run by a processor, the steps of the method for locating a high-resistance grounding fault in a distribution network are executed.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] 1. The present invention uses transition resistance to consume reactive power to zero to establish a fault section location equation and uses fault current as a constraint condition. Only one fault location equation is used to locate all fault types, and the influence of fault resistance on the single-ended impedance method is reduced, thereby improving the accuracy of locating high-resistance grounding faults in the distribution network.

[0061] 2. The present invention uses synchronous measurement of voltage and current signals of DG and substation, injects DG's contribution to fault current as primary current, and derives the calculation formula of fault current when the fault occurs in the upstream network and downstream network of DG, thereby improving the accuracy of fault current estimation.

[0062] 3. The present invention uses the Thevenin theorem to estimate the equivalent impedance of the distribution network downstream of the fault, which reduces the computational complexity of fault current estimation, ensures the accuracy of the fault current, and thus improves the accuracy of locating high-resistance grounding faults in the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a flow chart of a method for locating a high-resistance grounding fault in a distribution network based on an improved single-ended impedance method according to the present invention;

[0064] Figure 2a This is a simplified diagram of the power distribution line when there is no DG in the upstream power distribution network of the fault according to the present invention;

[0065] Figure 2b This is a simplified diagram of the power distribution line when there is a DG in the upstream power distribution network of the fault according to the present invention;

[0066] Figure 3a This is a simplified diagram of the power distribution line when there is no DG in the downstream power distribution network of the fault according to the present invention;

[0067] Figure 3b This is a simplified diagram of the power distribution line when there is a DG in the downstream power distribution network of the fault according to the present invention;

[0068] Figure 4 This is the IEEE34-node power distribution network diagram of the simulation case of the present invention;

[0069] Figure 5 It is a fault location error diagram of the present invention at different fault distances;

[0070] Figure 6 This is a positioning error diagram of the present invention under different signal-to-noise ratios. DETAILED DESCRIPTION

[0071] In this embodiment, Figure 1 As shown, a method for locating a high-resistance grounding fault in a distribution network based on an improved single-ended impedance method is performed in the following steps:

[0072] Step 1: Obtain the synchronously measured voltage and current signals of the main substation monitoring point and the distributed generation DG access node before and after the distribution network fails, and use the fast Fourier algorithm to obtain the three-phase voltage phasor [V abc ]'1 and three-phase current phasor [I abc ]'1. Three-phase voltage phase quantity after fault [V abc ]1 and three-phase current phasor [I abc ]1 and the three-phase current phasors of the hth DG access node after the fault occurs And three-phase voltage phasors

[0073] Step 2: Use the Π-type line model to make the distribution network equivalent. At the node with parallel branches, divide the distribution network into K sections and number each section. Let k represent the number of any section, k∈K; when k=1, the line head end of the kth section is the monitoring point of the main substation of the distribution network;

[0074] Step 3: Use equations (1) and (2) to obtain the three-phase voltage phasor [V abc ]' k+1 and the three-phase current phasor at the line head end [I abc ]' k+1 ; The three-phase voltage phasor at the head end of the line in the k+1th section after the fault occurs [V abc ] k+1 and the three-phase current phasor at the line head end [I abc ] k+1 :

[0075]

[0076]

[0077] In formula (1)-formula (2), [V abc ]' k represents the three-phase voltage phasor at the head end of the line at the kth section before the fault occurs, [I abc ]' k represents the three-phase current phasor at the head end of the line at the kth section before the fault occurs; [V abc ] k It represents the three-phase voltage phasor at the head end of the line at the kth section after the fault occurs, [I abc ] k represents the three-phase current phasor at the head end of the line in the kth section after the fault occurs; [a] k , [b] k , [c] k , [d] kare all third-order line matrices of the kth section, and have:

[0078]

[0079] [b] k =L k [z abc ] (4)

[0080]

[0081] In formula (3) to formula (5), [z abc ]、[y abc ] are the unit line impedance matrix and unit ground admittance matrix of the three-phase line of the distribution network respectively; E is the third-order unit matrix; L k is the line length of the kth section;

[0082] Step 3: Use equation (6) to obtain the initial fault current [I abc ] f,k :

[0083] [I abc ] f,k =[I abc ] k -[I abc ]′ k (6)

[0084] Step 4: Based on the transition resistance consuming zero reactive power, the positioning equation of the kth section is established using equation (7):

[0085]

[0086] In formula (7), x k represents the length of the line between the head end of the kth section and the fault point, that is, the fault distance of the kth section; α2 represents the quadratic coefficient, α1 represents the linear coefficient, α0 represents the constant term, and:

[0087]

[0088]

[0089]

[0090] In formula (8) to formula (10), Im{} is the imaginary part extraction symbol; Re{} is the real part extraction symbol; [] T is the transpose of the matrix;

[0091] Step 5: Execute the iterative algorithm:

[0092] Step 5.1: Define and initialize the number of iterations i = 1; initialize k = 1; set the initial fault current [I abc ] f,k As the fault current of the kth section at the i-th iteration

[0093] Step 5.2: Substitute the fault current of the kth section at the i-th iteration into Substituting into the location equation of the kth section, we get the fault distance of the kth section at the i-th iteration:

[0094] Step 5.3: Judgement Is it true? If so, jump to step 5.5. Otherwise, assign k+1 to k and jump to step 5.4:

[0095] Step 5.4: Determine whether k≤K holds. If so, jump to step 5.2; otherwise, end the iterative algorithm and jump to step 6;

[0096] Step 5.5: Judgement Is it true? If true, store the segment number k and the fault distance After assigning k+1 to k, jump to step 5.4; otherwise, assign i+1 to i, jump to step 5.6; where, is the fault distance of the kth segment at the i-1th iteration. When i=1, let ε is a positive number;

[0097] Step 5.6: Considering the contribution of DG to the fault current, calculate the magnitude of the fault current in the upstream and downstream networks of the fault point in the distribution network with or without DG:

[0098] Step 5.6.1: When the upstream network of the fault point does not contain DG, Figure 2a As shown, the upstream fault current of the kth section at the i-th iteration is obtained by using formula (11):

[0099]

[0100] In formula (11), N is the number of load branches between the head end and the fault point of the kth section at the i-th iteration; is the shunt current of the jth load branch, obtained by the forward-backward substitution power flow algorithm; represents the shunt current of the distributed capacitance of the line between the line headend and the fault point in the kth section in the i-th iteration, and is estimated using equation (12):

[0101]

[0102] Step 5.6.2: When the upstream network of the fault point contains DG, Figure 2b As shown, the upstream fault current of the kth section at the i-th iteration is obtained by using formula (13):

[0103]

[0104] In formula (13), M is the number of DGs in the upstream network of the fault point; is the line capacitance shunt current between the hth distributed generation and the kth section at the fault point of the i-th iteration, and is obtained using formula (14):

[0105]

[0106] Step 5.6.3: When the downstream network of the fault point does not contain DG, Figure 3a As shown, the downstream fault current of the kth section at the i-th iteration is obtained using formula (15):

[0107]

[0108] In formula (15), is the fault point voltage of the kth section at the i-th iteration and is calculated using formula (16); [Z abc ] thqf,k is the equivalent impedance of the downstream network of the kth section at the fault point in the i-th iteration, calculated using equation (17);

[0109]

[0110]

[0111] In formula (17), [Z abc ] thq,k is the equivalent impedance of the network downstream of the end node of the kth segment; is the line admittance matrix of the kth section between the fault point at the ith iteration and the end of the kth section; is the line impedance matrix between the fault point of the kth section at the ith iteration and the end of the kth section;

[0112] As Figure 3a Taking the fault point as an example, the equivalent impedance of the distribution network downstream of the fault point is calculated using the Thevenin theorem. The specific calculation process is as follows:

[0113] First, use equations (18) to (21) to calculate the equivalent impedance of each branch:

[0114]

[0115]

[0116] [Z abc ] thm1 =([Z abc ] m1 -1 +[Z abc ] thm1m2 -1 +[Z abc ] thm1m3 -1 ) -1 (20)

[0117]

[0118] Secondly, the equivalent impedance of each branch is combined and the equivalent impedance of the downstream network at the end node m of the fault section is obtained using formula (22): abc ] thm :

[0119] [Z abc ] thm =([Z abc ] m -1 +[Z abc ] thmm1 -1 ) -1 (twenty two)

[0120] Finally, the equivalent impedance [Z] of the distribution network downstream of the fault point of the kth section at the i-th iteration is calculated using formula (23). abc ] thq-f Perform the calculation:

[0121]

[0122] Step 5.6.4: When the downstream network of the fault point contains DG, Figure 3b As shown, using formula (24), the downstream fault current of the kth section at the i-th iteration is obtained

[0123]

[0124] In formula (24), M1 is the number of distributed generation in the downstream network of the fault point in the kth section at the i-th iteration, and N1 is the number of load branches between the h-th distributed generation and the fault point in the downstream network of the fault point in the kth section at the i-th iteration; is the shunt current of the jth load branch between the hth distributed generation and the fault point in the downstream network of the fault point in the kth section at the i-th iteration;

[0125] Step 5.7: Based on Kirchhoff's current law, use equation (25) to obtain the fault current of the kth section at the i-th iteration:

[0126]

[0127] Step 5.8: Substitute the fault current of the kth section estimated in step 5.5 at the i-th iteration into Substituting into equation (7), the positive real number solution is the fault distance of the kth section at the i+1th iteration: make And jump to step 5.3;

[0128] Step 6: Use formula (26) to obtain the fault distance x from the main substation of the distribution network to the fault point total :

[0129]

[0130] In formula (26), K1 is the number set of line sections between the fault section number k and the main substation of the distribution network.

[0131] In this embodiment, an electronic device includes a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the method for locating a high-resistance grounding fault in a distribution network, and the processor is configured to execute the program stored in the memory.

[0132] In this embodiment, a computer-readable storage medium stores a computer program on the computer-readable storage medium. When the computer program is executed by a processor, the steps of the method for locating a high-resistance grounding fault in a distribution network are executed.

[0133] In order to verify the effectiveness of the proposed method for locating high-resistance grounding faults in distribution networks based on the improved single-ended impedance method, some experiments were carried out. The platform used in the experiment is Window 10 system, the programming language is Matlab2021b, and the simulation platform is Matlab2021b / Simulink.

[0134] In this embodiment, the method is simulated and verified on the IEEE-34 node distribution network system. Figure 4 As shown. The Π-type line model is adopted, the asymmetry of the three-phase line parameters and different line parameters are taken into account, the load adopts a constant impedance model, and the DG model is connected at nodes 848 and 852 respectively. The robustness of the method is verified from several aspects, such as fault distance, fault type, fault resistance, and the influence of measurement error.

[0135] The experimental results show that although the positioning accuracy of the distribution network high-resistance grounding fault positioning method based on the improved single-ended impedance method proposed in the present invention will be reduced due to the increase of the fault distance, it can still ensure a good positioning accuracy. Figure 5 The present invention has good robustness to measurement noise, such as Figure 6 The present invention can locate all types of faults and is still effective in the case of high-resistance grounding.

Claims

1. A method for locating high-resistance grounding faults in a distribution network based on an improved single-ended impedance method, characterized in that: The steps include: Step 1: Obtain the synchronously measured voltage and current signals of the main substation monitoring point and the distributed generation DG access node before and after the distribution network fails, and use the fast Fourier algorithm to obtain the three-phase voltage phasor [V abc ]'1 and three-phase current phasor [I abc ]'1. Three-phase voltage phase quantity after fault [V abc ]1 and three-phase current phasor [I abc ]1 and the three-phase current phasors of the hth DG access node after the fault occurs And three-phase voltage phasors Step 2: Use the Π-type line model to make the distribution network equivalent. At the node with parallel branches, divide the distribution network into K sections and number each section. Let k represent the number of any section, k∈K; when k=1, the line head end of the kth section is the monitoring point of the main substation of the distribution network; Step 3: Use equations (1) and (2) to obtain the three-phase voltage phasor [V abc ]' k+1 and the three-phase current phasor at the line head end [I abc ]' k+1 ; The three-phase voltage phasor at the head end of the line in the k+1th section after the fault occurs [V abc ] k+1 and the three-phase current phasor at the line head end [I abc ] k+1 : In formula (1)-formula (2), [V abc ]' k represents the three-phase voltage phasor at the head end of the line at the kth section before the fault occurs, [I abc ]' k represents the three-phase current phasor at the head end of the line at the kth section before the fault occurs; [V abc ] k It represents the three-phase voltage phasor at the head end of the line at the kth section after the fault occurs, [I abc ] k represents the three-phase current phasor at the head end of the line in the kth section after the fault occurs; [a] k , [b] k , [c] k , [d] k are all third-order line matrices of the kth section, and have: [b] k =L k [z abc ] (4) In formula (3) to formula (5), [z abc ]、[y abc ] are the unit line impedance matrix and unit ground admittance matrix of the three-phase line of the distribution network respectively; E is the third-order unit matrix; L k is the line length of the kth section; Step 3: Use equation (6) to obtain the initial fault current [I abc ] f,k : [I abc ] f,k =[I abc ] k -[I abc ]′ k (6) Step 4: Based on the transition resistance consuming zero reactive power, the positioning equation of the kth section is established using equation (7): In formula (7), x k represents the length of the line between the head end of the kth section and the fault point, that is, the fault distance of the kth section; α2 represents the quadratic coefficient, α1 represents the linear coefficient, α0 represents the constant term, and: In formula (8) to formula (10), Im{} is the imaginary part extraction symbol; Re{} is the real part extraction symbol; [] T is the transpose of the matrix; Step 5: Execute the iterative algorithm: Step 5.1: Define and initialize the number of iterations i = 1; initialize k = 1; set the initial fault current [I abc ] f,k As the fault current of the kth section at the i-th iteration Step 5.2: Substitute the fault current of the kth section at the i-th iteration into Substituting into the location equation of the kth section, we get the fault distance of the kth section at the i-th iteration: Step 5.3: Judgement Is it true? If so, jump to step 5.

5. Otherwise, assign k+1 to k and jump to step 5.4: Step 5.4: Determine whether k≤K holds. If so, jump to step 5.2; otherwise, end the iterative algorithm and jump to step 6; Step 5.5: Judgement Is it true? If true, store the segment number k and the fault distance After assigning k+1 to k, jump to step 5.4; otherwise, assign i+1 to i, jump to step 5.6; where, is the fault distance of the kth segment at the i-1th iteration. When i=1, let ε is a positive number; Step 5.6: Considering the contribution of DG to the fault current, calculate the magnitude of the fault current in the upstream and downstream networks of the fault point in the distribution network with or without DG: Step 5.6.1: When the upstream network of the fault point does not contain DG, use equation (11) to obtain the upstream fault current of the kth section at the i-th iteration: In formula (11), N is the number of load branches between the head end and the fault point of the kth section at the i-th iteration; is the shunt current of the jth load branch, obtained by the forward-backward substitution power flow algorithm; represents the shunt current of the distributed capacitance of the line between the line headend and the fault point in the kth section in the i-th iteration, and is estimated using equation (12): Step 5.6.2: When the upstream network of the fault point contains DG, use equation (13) to obtain the upstream fault current of the kth section at the i-th iteration: In formula (13), M is the number of DGs in the upstream network of the fault point; is the line capacitance shunt current between the hth distributed generation and the kth section at the fault point of the i-th iteration, and is obtained using formula (14): Step 5.6.3: When the downstream network of the fault point does not contain DG, use equation (15) to obtain the downstream fault current of the kth section at the i-th iteration: In formula (15), is the fault point voltage of the kth section at the i-th iteration and is calculated using formula (16); [Z abc ] thqf,k is the equivalent impedance of the downstream network of the kth section at the fault point in the i-th iteration, calculated using equation (17); In formula (17), [Z abc ] thq,k is the equivalent impedance of the network downstream of the end node of the kth segment; is the line admittance matrix of the kth section between the fault point at the ith iteration and the end of the kth section; is the line impedance matrix between the fault point of the kth section at the ith iteration and the end of the kth section; Step 5.6.4: When the downstream network of the fault point contains DG, use equation (18) to obtain the downstream fault current of the kth section at the i-th iteration: In formula (18), M1 is the number of distributed generation in the downstream network of the fault point in the kth section at the i-th iteration, and N1 is the number of load branches between the h-th distributed generation and the fault point in the downstream network of the fault point in the kth section at the i-th iteration; is the shunt current of the jth load branch between the hth distributed generation and the fault point in the downstream network of the fault point in the kth section at the i-th iteration; Step 5.7: Based on Kirchhoff's current law, use equation (19) to obtain the fault current of the kth section at the i-th iteration: Step 5.8: Substitute the fault current of the kth section estimated in step 5.5 at the i-th iteration into Substituting into equation (7), the positive real number solution is the fault distance of the kth section at the i+1th iteration: make And jump to step 5.3; Step 6: Use formula (20) to obtain the fault distance x from the main substation of the distribution network to the fault point total : In formula (20), K1 is the number set of line sections between the fault section number k and the main substation of the distribution network.

2. An electronic device, comprising a memory and a processor, characterized in that: The memory is used to store a program that supports the processor to execute the method for locating a high-resistance grounding fault in a distribution network as claimed in claim 1, and the processor is configured to execute the program stored in the memory.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for locating a high-resistance grounding fault in a distribution network according to claim 1 are executed.

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