Direct-current power distribution network single-pole grounding fault isolation method and system

Abstract

The invention discloses a DC power distribution network single-pole grounding fault isolation method and system, and relates to the technical field of DC power distribution network monitoring, and the method comprises the steps: obtaining the working condition parameters of the head end of each line of a DC power distribution network, and carrying out the fault detection of each working condition parameter; and when the fault detection result is that the DC power distribution network has a fault, performing quadratic fitting processing according to the positive current break variable and the negative current break variable corresponding to the head end of each line based on a preset quadratic function to obtain a fault detection result, a plurality of positive current break variables and a plurality of negative current break variables corresponding to the head end of each line. And according to each concavity and convexity coefficient, carrying out single-pole grounding fault isolation on the DC power distribution network. The technical problems that in the prior art, fault detection is carried out on the direct-current power distribution network mainly based on a fault signal energy analysis method of wavelet transformation, but the method is large in calculated amount, the requirement for rapid fault isolation of the direct-current power distribution network is difficult to meet, and the operation reliability of the direct-current power distribution network is reduced are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current (DC) distribution network monitoring, and in particular to a method and system for isolating a single-pole grounding fault in a DC distribution network. Background Art

[0002] In recent years, with the rapid development of DC loads such as distributed power sources, electric vehicle charging facilities, and data centers, low-voltage DC distribution networks have become a key development direction for power systems due to their high efficiency, low losses, and ease of access to distributed power sources. Among DC distribution network grounding methods, IT grounding systems significantly improve power supply continuity by maintaining short-term power supply even in the event of a single-pole ground fault, making them widely used in applications requiring high power reliability. However, the single-pole ground fault current in IT systems is relatively low, making it difficult for traditional threshold-based insulation monitoring methods to quickly identify faults. This can lead to long-term latent faults, potentially evolving into bipolar short circuits, threatening equipment safety and potentially causing electrical fires.

[0003] At present, the existing technology mainly uses the fault signal energy analysis method based on wavelet transform to detect faults in DC distribution networks. However, the fault signal energy analysis method based on wavelet transform has a large amount of calculation and is difficult to meet the needs of rapid fault isolation in DC distribution networks, which reduces the reliability of DC distribution network operation. Summary of the Invention

[0004] The present invention provides a method and system for isolating single-pole grounding faults in a DC distribution network, which solves the technical problem that the prior art mainly uses a fault signal energy analysis method based on wavelet transform to perform fault detection on the DC distribution network. However, the fault signal energy analysis method based on wavelet transform has a large amount of calculation, is difficult to meet the requirements for rapid fault isolation in the DC distribution network, and reduces the reliability of the DC distribution network operation.

[0005] A first aspect of the present invention provides a method for isolating a single-pole grounding fault in a DC distribution network, comprising:

[0006] Acquiring operating parameters of each line head end of the DC distribution network, performing fault detection on each of the operating parameters, and obtaining corresponding fault detection results, multiple positive current mutation amounts, and multiple negative current mutation amounts;

[0007] When the fault detection result is that a fault occurs in the DC distribution network, a quadratic fitting process is performed based on a preset quadratic function according to the positive current mutation amount and the negative current mutation amount corresponding to each of the line head ends to obtain a plurality of concavity and convexity coefficients;

[0008] Single-pole grounding fault isolation is performed on the DC distribution network according to each of the concavity and convexity coefficients.

[0009] Optionally, the operating condition parameters include positive electrode current, negative electrode current, positive electrode voltage, and negative electrode voltage, and the step of performing fault detection on each of the operating condition parameters to obtain corresponding fault detection results, multiple positive electrode current mutation amounts, and multiple negative electrode current mutation amounts includes:

[0010] performing mutation calculations on each of the positive electrode currents, each of the negative electrode currents, each of the positive electrode voltages, and each of the negative electrode voltages, respectively, to obtain a plurality of positive electrode current mutation amounts, a plurality of negative electrode current mutation amounts, a plurality of positive electrode voltage mutation amounts, and a plurality of negative electrode voltage mutation amounts;

[0011] Determine whether the absolute value of each of the positive electrode current mutation amounts, the absolute value of each of the negative electrode current mutation amounts, the absolute value of each of the positive electrode voltage mutation amounts, and the absolute value of each of the negative electrode voltage mutation amounts are all less than or equal to corresponding set values;

[0012] If the absolute value of each of the positive current mutation amounts, the absolute value of each of the negative current mutation amounts, the absolute value of each of the positive voltage mutation amounts, and the absolute value of each of the negative voltage mutation amounts are all less than or equal to the corresponding set values, then the normal operation of the DC distribution network is determined as the corresponding fault detection result;

[0013] If the absolute value of any of the positive current mutation amounts, the absolute value of any of the negative current mutation amounts, the absolute value of any of the positive voltage mutation amounts, or the absolute value of any of the negative voltage mutation amounts is greater than the corresponding set value, a fault in the DC distribution network is determined as the corresponding fault detection result.

[0014] Optionally, the step of performing mutation calculation on each of the positive electrode currents, each of the negative electrode currents, each of the positive electrode voltages, and each of the negative electrode voltages to obtain multiple positive electrode current mutation amounts, multiple negative electrode current mutation amounts, multiple positive electrode voltage mutation amounts, and multiple negative electrode voltage mutation amounts includes:

[0015] performing difference processing on each of the positive electrode currents and the corresponding positive electrode reference current to obtain a plurality of positive electrode current mutation amounts;

[0016] performing difference processing on each of the negative electrode currents and the corresponding negative electrode reference current to obtain a plurality of negative electrode current mutation amounts;

[0017] performing difference processing on each of the positive electrode voltages and the corresponding positive electrode reference voltage to obtain a plurality of positive electrode voltage mutation amounts;

[0018] Each of the negative electrode voltages is subjected to difference processing with a corresponding negative electrode reference voltage to obtain a plurality of negative electrode voltage mutation amounts.

[0019] Optionally, the step of performing quadratic fitting processing based on a preset quadratic function according to the positive current mutation amount and the negative current mutation amount corresponding to each of the line head ends to obtain a plurality of concavity and convexity coefficients includes:

[0020] Obtaining historical positive current mutation data and historical negative current mutation data of each line head end, and solving a preset quadratic function using the historical positive current mutation data and positive current mutation amount corresponding to each line head end, to obtain multiple positive quadratic functions;

[0021] The quadratic function is solved by respectively using the historical negative pole mutation data and the negative pole current mutation amount corresponding to the line head end to obtain multiple negative pole quadratic functions;

[0022] Performing quadratic curve fitting on the corresponding positive electrode current mutation using each of the positive electrode quadratic functions to obtain a plurality of positive electrode quadratic fitting curves;

[0023] Performing quadratic curve fitting on the corresponding negative electrode current mutation using each of the negative electrode quadratic functions to obtain a plurality of negative electrode quadratic fitting curves;

[0024] The positive quadratic fitting curve and the negative quadratic curve corresponding to each of the line head ends are respectively subjected to curvature determination processing to obtain a plurality of concavity and convexity coefficients.

[0025] Optionally, the step of performing curvature determination processing on the positive quadratic fitting curve and the negative quadratic curve corresponding to each of the line head ends to obtain a plurality of concavity and convexity coefficients includes:

[0026] performing a second-order derivative operation on each of the positive electrode quadratic fitting curves to obtain a plurality of positive electrode second-order derivatives;

[0027] performing a second-order derivative operation on each of the negative electrode quadratic fitting curves to obtain a plurality of negative electrode second-order derivatives;

[0028] The positive second-order derivative and the negative second-order derivative corresponding to each of the line head ends are multiplied to obtain a plurality of concavity and convexity coefficients.

[0029] Optionally, the step of isolating a single-pole grounding fault in the DC distribution network according to each of the concavity and convexity coefficients includes:

[0030] Determining whether each of the concavity and convexity coefficients is less than a preset action threshold;

[0031] When the concavity-convexity coefficient is less than the action threshold, the upstream protection measuring point corresponding to the concavity-convexity coefficient is determined as the measuring point to be analyzed;

[0032] Obtaining the zero-mode voltage of each of the measurement points to be analyzed, and determining whether the absolute value of each of the zero-mode voltages is greater than a preset voltage setting value;

[0033] When the absolute value of the zero-mode voltage is greater than the voltage setting value, the to-be-analyzed measuring point associated with the zero-mode voltage is determined as a target measuring point;

[0034] Based on the preset action delay, single-pole grounding fault isolation is performed on each target measuring point in the DC distribution network.

[0035] A second aspect of the present invention provides a DC distribution network single-pole grounding fault isolation system, comprising:

[0036] An acquisition module is used to obtain operating parameters of the headend of each line of the DC distribution network, perform fault detection on each of the operating parameters, and obtain corresponding fault detection results, multiple positive current mutation amounts, and multiple negative current mutation amounts;

[0037] an analysis module configured to, when the fault detection result indicates a fault in the DC distribution network, perform quadratic fitting processing based on a preset quadratic function on the positive current mutation amount and the negative current mutation amount corresponding to each of the line head ends to obtain a plurality of concavity and convexity coefficients;

[0038] An isolation module is used to isolate single-pole grounding faults in the DC distribution network according to each of the concavity and convexity coefficients.

[0039] A third aspect of the present invention provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the steps of the method for isolating a single-pole grounding fault in a DC distribution network as described in any one of the above items.

[0040] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, the method for isolating a single-pole grounding fault in a DC distribution network as described in any one of the above items is implemented.

[0041] A fifth aspect of the present invention provides a computer program product, comprising a computer program stored on a non-transitory computer-readable storage medium, wherein the computer program includes program instructions, wherein when the program instructions are executed by a computer, the computer is caused to execute the method for isolating a single-pole grounding fault in a DC distribution network as described in any one of the above items.

[0042] It can be seen from the above technical solutions that the present invention has the following advantages:

[0043] The present invention obtains operating parameters at the headends of each line in a DC distribution network, performs fault detection on each operating parameter, and obtains corresponding fault detection results, multiple positive current mutations, and multiple negative current mutations. When the fault detection result indicates a DC distribution network fault, a quadratic fitting process is performed based on the positive current mutations and negative current mutations corresponding to each line headend, based on a preset quadratic function, to obtain multiple concavity coefficients. Single-pole grounding fault isolation is then performed on the DC distribution network based on these concavity coefficients. This overcomes the technical problem that existing techniques for DC distribution network fault detection primarily rely on wavelet transform-based fault signal energy analysis methods, which are computationally intensive and difficult to meet the requirements for rapid fault isolation in DC distribution networks, thus reducing the reliability of DC distribution network operation. Compared with traditional DC distribution network fault detection methods, the present invention performs quadratic fitting processing based on a preset quadratic function according to the positive current mutation amount and the negative current mutation amount corresponding to the head end of each line to obtain multiple concavity and convexity coefficients. Then, the DC distribution network fault is quickly located using each concavity and convexity coefficient, thereby achieving fault isolation of the DC distribution network and improving the reliability of the DC distribution network operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 A flowchart of a method for isolating a single-pole grounding fault in a DC distribution network provided in accordance with the first embodiment of the present invention;

[0046] Figure 2 A flowchart of a method for isolating a single-pole grounding fault in a DC distribution network provided in a second embodiment of the present invention;

[0047] Figure 3 A schematic diagram of a low-voltage DC distribution network provided in the second embodiment of the present invention;

[0048] Figure 4 This is a structural block diagram of a DC distribution network single-pole grounding fault isolation system provided by the third embodiment of the present invention;

[0049] Figure 5 This is a structural block diagram of a computer device provided in Example 4 of the present invention. DETAILED DESCRIPTION

[0050] The embodiments of the present invention provide a method and system for isolating a single-pole grounding fault in a DC distribution network, which is used to solve the technical problem that the existing technology mainly uses a fault signal energy analysis method based on wavelet transform to perform fault detection on the DC distribution network. However, the fault signal energy analysis method based on wavelet transform has a large computational complexity, which makes it difficult to meet the requirements for rapid fault isolation in the DC distribution network, thereby reducing the reliability of the DC distribution network operation.

[0051] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0052] See also Figure 1 , Figure 1 This is a flowchart of the steps of a method for isolating a single-pole grounding fault in a DC distribution network provided in Embodiment 1 of the present invention.

[0053] The present invention provides a method for isolating a single-pole grounding fault in a DC distribution network, comprising:

[0054] Step 101: Acquire operating parameters of the headends of each line in the DC distribution network, perform fault detection on each operating parameter, and obtain corresponding fault detection results, multiple positive current mutation amounts, and multiple negative current mutation amounts.

[0055] The operating parameters refer to the positive current, negative current, positive voltage and negative voltage at the head end of the line at the current moment.

[0056] The positive electrode current mutation refers to the instantaneous change of the positive electrode current.

[0057] The negative electrode current mutation refers to the instantaneous change of the negative electrode current.

[0058] In an embodiment of the present invention, based on a preset mutation amount function, mutation amount calculations are performed on each positive electrode current, each negative electrode current, each positive electrode voltage, and each negative electrode voltage, respectively, to obtain multiple positive electrode current mutation amounts, multiple negative electrode current mutation amounts, multiple positive electrode voltage mutation amounts, and multiple negative electrode voltage mutation amounts. When the absolute value of each positive electrode current mutation amount, the absolute value of each negative electrode current mutation amount, the absolute value of each positive electrode voltage mutation amount, and the absolute value of each negative electrode voltage mutation amount are all less than or equal to corresponding set values, the DC distribution network is determined to be operating normally as the corresponding fault detection result. When the absolute value of any positive electrode current mutation amount, the absolute value of any negative electrode current mutation amount, the absolute value of any positive electrode voltage mutation amount, or the absolute value of any negative electrode voltage mutation amount is greater than the corresponding set value, the DC distribution network is determined to have a fault as the corresponding fault detection result.

[0059] It should be noted that the mutation amount function is specifically:

[0060] ;

[0061] ;

[0062] in, is the positive current mutation at the head end of the i-th line, is the negative current mutation at the head end of the i-th line, is the positive current at the head end of the i-th line at the current moment, is the negative current at the head end of the i-th line at the current moment, is the positive current at the head end of the i-th line at the previous moment, is the negative current at the head end of the i-th line at the previous moment, is the positive voltage mutation at the head end of the i-th line, is the negative voltage mutation at the head end of the i-th line, is the positive voltage at the head end of the i-th line at the current moment, is the positive voltage at the head end of the i-th line at the previous moment, is the negative voltage at the head end of the i-th line at the current moment, is the negative voltage at the head end of the i-th line at the previous moment, and i is the index of the line.

[0063] Step 102: When the fault detection result indicates that a fault has occurred in the DC distribution network, a quadratic fitting process is performed based on a preset quadratic function according to the positive current mutation amount and the negative current mutation amount corresponding to each line head end to obtain a plurality of concavity and convexity coefficients.

[0064] In an embodiment of the present invention, when the fault detection result indicates a DC distribution network fault, historical positive and negative current mutation data are obtained from the headend of each line. A preset quadratic function is solved using the historical positive mutation data and the positive current mutation amount corresponding to each line headend, respectively, to obtain multiple positive quadratic functions. The quadratic function is solved using the historical negative mutation data and the negative current mutation amount corresponding to each line headend, respectively, to obtain multiple negative quadratic functions. Quadratic curve fitting is performed on the corresponding positive current mutation amount using each positive quadratic function, respectively, to obtain multiple positive quadratic fitting curves. Quadratic curve fitting is performed on the corresponding negative current mutation amount using each negative quadratic function, respectively, to obtain multiple negative quadratic fitting curves. Curvature determination processing is performed on the positive and negative quadratic curves corresponding to each line headend, respectively, to obtain multiple concavity / convexity coefficients.

[0065] It should be noted that the quadratic function is specifically:

[0066]

[0067] in, is the polar current mutation amount, is the first fitting coefficient, is the second fitting coefficient, is the third fitting coefficient, For time.

[0068] Step 103: Isolate the single-pole grounding fault of the DC distribution network according to the concavity and convexity coefficients.

[0069] It should be noted that single-pole ground fault isolation refers to locating the fault line based on the concavity coefficient and cutting off the fault line to ensure continuous power supply to the non-fault part.

[0070] In this embodiment of the present invention, when the concavity coefficient is less than the action threshold, the upstream protection measuring point corresponding to the concavity coefficient is identified as the measuring point to be analyzed. The zero-mode voltage of each measuring point to be analyzed is obtained, and a determination is made as to whether the absolute value of each zero-mode voltage is greater than a preset voltage setting value. If the absolute value of the zero-mode voltage is greater than the voltage setting value, the measuring point to be analyzed associated with the zero-mode voltage is identified as the target measuring point. Based on a preset action delay, single-pole grounding fault isolation is performed at each target measuring point in the DC distribution network.

[0071] In an embodiment of the present invention, operating parameters at the headends of each line in a DC distribution network are acquired, and fault detection is performed on each operating parameter to obtain corresponding fault detection results, multiple positive current mutations, and multiple negative current mutations. When the fault detection result indicates a DC distribution network fault, quadratic fitting is performed based on the positive current mutations and negative current mutations corresponding to each line headend, respectively, based on a preset quadratic function, to obtain multiple concavity coefficients. Single-pole grounding fault isolation is then performed on the DC distribution network based on these concavity coefficients. This overcomes the technical problem that prior art methods for DC distribution network fault detection primarily rely on wavelet transform-based fault signal energy analysis, which suffers from high computational complexity, making it difficult to meet the requirements for rapid fault isolation in DC distribution networks and reducing the reliability of DC distribution network operation. Compared with traditional DC distribution network fault detection methods, the present invention performs quadratic fitting processing based on a preset quadratic function according to the positive current mutation amount and the negative current mutation amount corresponding to the head end of each line to obtain multiple concavity and convexity coefficients. Then, the DC distribution network fault is quickly located using each concavity and convexity coefficient, thereby achieving fault isolation of the DC distribution network and improving the reliability of the DC distribution network operation.

[0072] See also Figure 2 , Figure 2 This is a flowchart of the steps of a method for isolating a single-pole grounding fault in a DC distribution network provided in the second embodiment of the present invention.

[0073] The present invention provides a method for isolating a single-pole grounding fault in a DC distribution network, comprising:

[0074] Step 201: Acquire operating parameters of the headends of each line in the DC distribution network, perform fault detection on each operating parameter, and obtain corresponding fault detection results, multiple positive current mutation amounts, and multiple negative current mutation amounts.

[0075] Furthermore, the operating parameters include positive electrode current, negative electrode current, positive electrode voltage, and negative electrode voltage. Step 201 includes the following sub-steps:

[0076] S11. Perform mutation calculations on each positive electrode current, each negative electrode current, each positive electrode voltage, and each negative electrode voltage, respectively, to obtain multiple positive electrode current mutations, multiple negative electrode current mutations, multiple positive electrode voltage mutations, and multiple negative electrode voltage mutations.

[0077] Furthermore, S11 includes the following sub-steps:

[0078] S111 , performing difference processing on each positive electrode current and the corresponding positive electrode reference current to obtain a plurality of positive electrode current mutation amounts.

[0079] The positive electrode reference current refers to the positive electrode current at the previous moment.

[0080] In the embodiment of the present invention, the difference between each positive electrode current and the corresponding positive electrode reference current is calculated respectively to obtain a plurality of positive electrode current mutation amounts.

[0081] S112 , performing difference processing on each negative electrode current and the corresponding negative electrode reference current to obtain a plurality of negative electrode current mutation amounts.

[0082] The negative electrode reference current refers to the negative electrode current at the previous moment.

[0083] In the embodiment of the present invention, the difference between each negative electrode current and the corresponding negative electrode reference current is calculated respectively to obtain a plurality of negative electrode current mutation amounts.

[0084] S113 , performing difference processing on each positive electrode voltage and the corresponding positive electrode reference voltage to obtain a plurality of positive electrode voltage mutation amounts.

[0085] The positive electrode reference voltage refers to the positive electrode voltage at the previous moment.

[0086] The positive electrode voltage mutation refers to the instantaneous change of the positive electrode voltage.

[0087] In the embodiment of the present invention, the difference between each positive electrode voltage and the corresponding positive electrode reference voltage is calculated respectively to obtain a plurality of positive electrode voltage mutation amounts.

[0088] S114 , performing difference processing on each negative electrode voltage and the corresponding negative electrode reference voltage to obtain a plurality of negative electrode voltage mutation amounts.

[0089] The negative electrode reference voltage refers to the negative electrode voltage at the previous moment.

[0090] The negative electrode voltage mutation refers to the instantaneous change of the negative electrode voltage.

[0091] In the embodiment of the present invention, the difference between each negative electrode voltage and the corresponding negative electrode reference voltage is calculated respectively to obtain a plurality of negative electrode voltage mutation amounts.

[0092] S12. Determine whether the absolute value of each positive electrode current mutation, the absolute value of each negative electrode current mutation, the absolute value of each positive electrode voltage mutation, and the absolute value of each negative electrode voltage mutation are all less than or equal to the corresponding set value.

[0093] In an embodiment of the present invention, it is determined whether each positive electrode current mutation amount, each negative electrode current mutation amount, each positive electrode voltage mutation amount, and each negative electrode voltage mutation amount all meet a preset fault criterion condition.

[0094] It should be noted that the specific fault judgment conditions are:

[0095] ;

[0096] ;

[0097] in, is the setting value for starting the current sudden change, is the voltage mutation starting value.

[0098] S13. If the absolute value of each positive current mutation amount, the absolute value of each negative current mutation amount, the absolute value of each positive voltage mutation amount, and the absolute value of each negative voltage mutation amount are all less than or equal to the corresponding set value, the normal operation of the DC distribution network is determined as the corresponding fault detection result.

[0099] In an embodiment of the present invention, if each positive electrode current mutation amount, each negative electrode current mutation amount, each positive electrode voltage mutation amount, and each negative electrode voltage mutation amount do not meet the preset fault judgment conditions, the normal operation of the DC distribution network is determined as the corresponding fault detection result.

[0100] S14. If the absolute value of any positive current mutation, the absolute value of any negative current mutation, the absolute value of any positive voltage mutation, or the absolute value of any negative voltage mutation is greater than the corresponding set value, a fault in the DC distribution network is determined as the corresponding fault detection result.

[0101] In an embodiment of the present invention, if any positive current mutation, any negative current mutation, any positive voltage mutation, or any negative voltage mutation meets a preset fault criterion condition, a fault in the DC distribution network is determined as a corresponding fault detection result.

[0102] Step 202: When the fault detection result indicates that a DC distribution network fault has occurred, historical positive current mutation data and historical negative current mutation data of the head end of each line are obtained, and the historical positive current mutation data and positive current mutation amount corresponding to the head end of each line are used to solve a preset quadratic function to obtain multiple positive quadratic functions.

[0103] The historical positive current mutation data refers to a discrete sampling value sequence of the positive current changing over time in a DC distribution network under normal or fault conditions.

[0104] The historical negative pole current mutation data refers to a discrete sampling value sequence of the negative pole current changing over time in a DC distribution network under normal or fault conditions.

[0105] In an embodiment of the present invention, when the fault detection result is a fault in the DC distribution network, the historical positive current mutation data and the historical negative current mutation data of the head end of each line are obtained, and the minimization of the residual sum of squares is used as the fitting target. The historical positive current mutation data and the positive current mutation amount corresponding to the head end of each line are used to solve the preset quadratic function to obtain multiple positive quadratic functions.

[0106] It should be noted that the specific process of solving the quadratic function is:

[0107] A1. Based on the quadratic function, a fitting quadratic function is constructed with the minimum sum of squared residuals as the fitting objective.

[0108] The fitting quadratic function is specifically:

[0109] ;

[0110] in, is the residual sum of squares, is the nth time series, n is the mutation index, and N is the total number of mutations.

[0111] A2. Calculate the partial derivatives of the first, second, and third fitting coefficients and set the derivatives to zero to obtain a fitted quadratic equation system.

[0112] The specific fitting quadratic equations are:

[0113] ;

[0114] A3. Solve the fitted quadratic equation system to obtain the fitted quadratic matrix.

[0115] The fitting quadratic matrix is ​​specifically:

[0116] ;

[0117] A4. Using historical positive electrode mutation data and positive electrode current mutations to solve a fitted quadratic matrix, a first fitting coefficient, a second fitting coefficient, and a third fitting coefficient corresponding to each positive electrode current mutation can be obtained. The first fitting coefficient, the second fitting coefficient, and the third fitting coefficient corresponding to each positive electrode current mutation are respectively input into the quadratic function to obtain multiple positive electrode quadratic functions.

[0118] Step 203 : Solve the quadratic function using the historical negative pole mutation data and the negative pole current mutation corresponding to the line head end to obtain multiple negative pole quadratic functions.

[0119] In the embodiment of the present invention, the quadratic function is solved by respectively using the historical negative pole mutation data and the negative pole current mutation amount corresponding to the line head end to obtain a plurality of negative pole quadratic functions.

[0120] Step 204 : Perform quadratic curve fitting on the corresponding positive electrode current mutation using each positive electrode quadratic function to obtain a plurality of positive electrode quadratic fitting curves.

[0121] In the embodiment of the present invention, a quadratic curve fitting is performed on the corresponding positive current mutation amount through each positive quadratic function to obtain multiple positive quadratic fitting curves. .

[0122] Step 205 : Perform quadratic curve fitting on the corresponding negative electrode current mutation using each negative electrode quadratic function to obtain a plurality of negative electrode quadratic fitting curves.

[0123] In the embodiment of the present invention, a quadratic curve fitting is performed on the corresponding negative electrode current mutation amount through each negative electrode quadratic function to obtain multiple negative electrode quadratic fitting curves. .

[0124] Step 206 : Perform curvature determination processing on the positive quadratic fitting curve and the negative quadratic curve corresponding to the head end of each line to obtain a plurality of concavity and convexity coefficients.

[0125] Furthermore, step 206 includes the following sub-steps:

[0126] S21. Perform a second-order derivative operation on each positive electrode quadratic fitting curve to obtain multiple positive electrode second-order derivatives.

[0127] In the embodiment of the present invention, the second-order derivative of each positive electrode quadratic fitting curve is calculated respectively to obtain a plurality of positive electrode second-order derivatives.

[0128] S22. Perform a second-order derivative operation on each negative electrode quadratic fitting curve to obtain multiple negative electrode second-order derivatives.

[0129] In the embodiment of the present invention, the second-order derivative of each negative electrode quadratic fitting curve is calculated respectively to obtain a plurality of negative electrode second-order derivatives.

[0130] S23. Multiply the positive second-order derivative and the negative second-order derivative corresponding to the head end of each line respectively to obtain a plurality of concavity and convexity coefficients.

[0131] In the embodiment of the present invention, the product of the positive second-order derivative and the negative second-order derivative corresponding to the head end of each line is calculated respectively to obtain a plurality of concavity and convexity coefficients.

[0132] It should be noted that the expression of the concavity coefficient is:

[0133]

[0134] in, is the concavity coefficient of the i-th line, is the positive second-order derivative of the ith circuit, is the negative second-order derivative of the ith circuit.

[0135] It should be noted that the concavity coefficient only requires current data from the line headend and is calculated locally using a quadratic curve fitting of the positive and negative current mutations. This eliminates the need for communication or collaborative analysis, significantly reducing computational costs. Furthermore, quadratic curve fitting smoothes current mutations, suppressing random noise interference and avoiding misjudgments caused by transient fluctuations.

[0136] Step 207: Isolate the single-pole grounding fault of the DC distribution network according to the concavity and convexity coefficients.

[0137] Furthermore, step 207 includes the following sub-steps:

[0138] S31. Determine whether each concavity / convexity coefficient is less than a preset action threshold.

[0139] The action threshold refers to the critical value at which the fault point is located at the measurement point. The value is 0.

[0140] In the embodiment of the present invention, it is determined whether each concavity-convexity coefficient is less than 0.

[0141] S32. When the concavity-convexity coefficient is less than the action threshold, the upstream protection measuring point corresponding to the concavity-convexity coefficient is determined as a measuring point to be analyzed.

[0142] In the embodiment of the present invention, when the concavity-convexity coefficient is a negative number, the upstream protection measuring point corresponding to the concavity-convexity coefficient is determined as the measuring point to be analyzed.

[0143] S33. Obtain the zero-mode voltage of each measurement point to be analyzed, and determine whether the absolute value of each zero-mode voltage is greater than a preset voltage setting value.

[0144] In an embodiment of the present invention, the zero-mode voltage of each measurement point to be analyzed is obtained, and it is determined whether the absolute value of each zero-mode voltage is greater than a preset voltage setting value.

[0145] S34. When the absolute value of the zero-mode voltage is greater than the voltage setting value, the to-be-analyzed measuring point associated with the zero-mode voltage is determined as the target measuring point.

[0146] In an embodiment of the present invention, if the absolute value of the zero-mode voltage is greater than the voltage setting value, the to-be-analyzed measuring point associated with the zero-mode voltage is determined as the target measuring point.

[0147] S35. Based on the preset action delay, single-pole grounding fault isolation is performed on each target measuring point in the DC distribution network.

[0148] In an embodiment of the present invention, a single-pole ground fault is isolated at each target measuring point in a DC distribution network based on a preset action delay. For example, according to the preset action delay, a security device associated with each target measuring point in the DC distribution network is controlled to trip with a delay.

[0149] It should be noted that, see Figure 3 As shown, for the three-level line, if line 4 fails, then (i.e. the concavity coefficient at the beginning of the first line), (i.e. the concave-convex coefficient at the head end of the second line), (i.e. the concave-convex coefficient at the head end of the fourth line) are all negative. Without considering the delay issues such as circuit breaker opening, protection 4 should trip in 0s; before protection 2 operates, it detects whether the absolute value of the line zero-mode voltage is greater than the voltage setting value (i.e. first determine whether the fault still exists). If protection 4 successfully trips, the system zero voltage does not exist, and protection 2 does not operate. If protection 4 refuses to operate, the absolute value of the zero-mode voltage detected by protection 2 is greater than the voltage setting value, and protection 2 delays ( The first delay is preset) action (that is, protection 2 is determined as the target measuring point); similar to protection 2, protection 1 first determines the zero pressure, and if the start condition is met, the delay ( The circuit breaker trips when the second delay is set.

[0150] It is worth mentioning that the sign determination of the concavity coefficient only requires a single fitting calculation (i.e., judging whether each concavity coefficient is less than the preset action threshold). Combined with differential protection, fault location and isolation can be completed within 20ms, meeting the rapid protection requirements of low-inertia DC distribution networks.

[0151] In an embodiment of the present invention, operating parameters at the headends of each line in a DC distribution network are acquired, and fault detection is performed on each operating parameter to obtain corresponding fault detection results, multiple positive current mutations, and multiple negative current mutations. When the fault detection result indicates a DC distribution network fault, quadratic fitting is performed based on the positive current mutations and negative current mutations corresponding to each line headend, respectively, based on a preset quadratic function, to obtain multiple concavity coefficients. Single-pole grounding fault isolation is then performed on the DC distribution network based on these concavity coefficients. This overcomes the technical problem that prior art methods for DC distribution network fault detection primarily rely on wavelet transform-based fault signal energy analysis, which suffers from high computational complexity, making it difficult to meet the requirements for rapid fault isolation in DC distribution networks and reducing the reliability of DC distribution network operation. Compared with traditional DC distribution network fault detection methods, the present invention performs quadratic fitting processing based on a preset quadratic function according to the positive current mutation amount and the negative current mutation amount corresponding to the head end of each line to obtain multiple concavity and convexity coefficients. Then, the DC distribution network fault is quickly located using each concavity and convexity coefficient, thereby achieving fault isolation of the DC distribution network and improving the reliability of the DC distribution network operation.

[0152] See also Figure 4 , Figure 4 This is a structural block diagram of a DC distribution network single-pole grounding fault isolation system provided by the third embodiment of the present invention.

[0153] The present invention provides a DC distribution network single-pole grounding fault isolation system, comprising:

[0154] The acquisition module 301 is used to obtain the operating parameters of each line head end of the DC distribution network, perform fault detection on each operating parameter, and obtain corresponding fault detection results, multiple positive current mutation amounts, and multiple negative current mutation amounts;

[0155] Analysis module 302 is configured to, when the fault detection result indicates a DC distribution network fault, perform quadratic fitting based on a preset quadratic function on the positive current mutation amount and the negative current mutation amount corresponding to each line head end to obtain a plurality of concavity and convexity coefficients;

[0156] The isolation module 303 is configured to isolate single-pole grounding faults in the DC distribution network according to the concavity and convexity coefficients.

[0157] Furthermore, the operating parameters include positive electrode current, negative electrode current, positive electrode voltage and negative electrode voltage, and the acquisition module 301 includes:

[0158] A mutation amount operation submodule is used to perform mutation amount operations on each positive electrode current, each negative electrode current, each positive electrode voltage and each negative electrode voltage respectively, to obtain multiple positive electrode current mutation amounts, multiple negative electrode current mutation amounts, multiple positive electrode voltage mutation amounts and multiple negative electrode voltage mutation amounts;

[0159] The first analysis submodule is used to determine whether the absolute value of each positive electrode current mutation amount, the absolute value of each negative electrode current mutation amount, the absolute value of each positive electrode voltage mutation amount, and the absolute value of each negative electrode voltage mutation amount are all less than or equal to the corresponding set value;

[0160] If the absolute value of each positive current mutation, the absolute value of each negative current mutation, the absolute value of each positive voltage mutation, and the absolute value of each negative voltage mutation are all less than or equal to the corresponding set value, the DC distribution network is determined to be operating normally as the corresponding fault detection result;

[0161] If the absolute value of any positive current mutation, the absolute value of any negative current mutation, the absolute value of any positive voltage mutation, or the absolute value of any negative voltage mutation is greater than the corresponding set value, a fault in the DC distribution network is determined as the corresponding fault detection result.

[0162] Furthermore, the mutation operator module includes:

[0163] The first mutation amount calculation unit is used to perform difference processing on each positive electrode current and the corresponding positive electrode reference current to obtain multiple positive electrode current mutation amounts;

[0164] The second mutation amount calculation unit is used to perform difference processing on each negative electrode current and the corresponding negative electrode reference current to obtain multiple negative electrode current mutation amounts;

[0165] a third mutation amount calculation unit, configured to perform difference processing on each positive electrode voltage and the corresponding positive electrode reference voltage to obtain a plurality of positive electrode voltage mutation amounts;

[0166] The fourth mutation amount calculation unit is used to perform difference processing on each negative electrode voltage and the corresponding negative electrode reference voltage to obtain multiple negative electrode voltage mutation amounts.

[0167] Furthermore, the analysis module 302 includes:

[0168] The acquisition submodule is used to obtain the historical positive current mutation data and the historical negative current mutation data of each line head end, and respectively use the historical positive current mutation data and the positive current mutation amount corresponding to each line head end to solve the preset quadratic function to obtain multiple positive quadratic functions;

[0169] The second analysis submodule is used to solve the quadratic function using the historical negative pole mutation data and the negative pole current mutation corresponding to the line head end to obtain multiple negative pole quadratic functions;

[0170] The quadratic functions of each positive electrode are respectively used to perform quadratic curve fitting on the corresponding positive electrode current mutation amount to obtain multiple positive electrode quadratic fitting curves;

[0171] Using each negative electrode quadratic function to perform quadratic curve fitting on the corresponding negative electrode current mutation, a plurality of negative electrode quadratic fitting curves are obtained;

[0172] The third analysis submodule is used to perform curvature determination processing on the positive quadratic fitting curve and the negative quadratic curve corresponding to the head end of each line to obtain multiple concavity and convexity coefficients.

[0173] Furthermore, the third analysis submodule includes:

[0174] A first derivative unit is used to perform a second-order derivative operation on each positive electrode quadratic fitting curve to obtain multiple positive electrode second-order derivatives;

[0175] A second derivative unit is used to perform a second-order derivative operation on each negative electrode quadratic fitting curve to obtain multiple negative electrode second-order derivatives;

[0176] The concave-convex analysis unit is used to multiply the positive second-order derivative and the negative second-order derivative corresponding to the head end of each line respectively to obtain multiple concave-convex coefficients.

[0177] Furthermore, the isolation module 303 includes:

[0178] The first isolation submodule is used to determine whether each concavity and convexity coefficient is less than a preset action threshold;

[0179] When the concavity and convexity coefficient is less than the action threshold, the upstream protection measuring point corresponding to the concavity and convexity coefficient is determined as the measuring point to be analyzed;

[0180] The second isolation submodule is used to obtain the zero-mode voltage of each measurement point to be analyzed and determine whether the absolute value of each zero-mode voltage is greater than a preset voltage setting value;

[0181] When the absolute value of the zero-mode voltage is greater than the voltage setting value, the measurement point to be analyzed associated with the zero-mode voltage is determined as the target measurement point;

[0182] Based on the preset action delay, single-pole grounding fault isolation is performed on each target measuring point in the DC distribution network.

[0183] See also Figure 5 , Figure 5 This is a structural block diagram of a computer device provided in Example 4 of the present invention.

[0184] An electronic device according to an embodiment of the present invention includes: a memory 401 and a processor 402, wherein the memory 401 stores a computer program; when the computer program is executed by the processor 402, the processor 402 executes the method for isolating a single-pole grounding fault in a DC distribution network according to any of the above embodiments.

[0185] Memory 401 may be an electronic memory such as flash memory, EEPROM (Electrically Erasable Programmable Read-Only Memory), EPROM, hard disk, or ROM. Memory 401 has storage space 403 for program code 413 for executing any of the method steps described above. For example, storage space 403 for program code may include individual program codes 413 for implementing various steps in the method described above. These program codes may be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, compact disks (CDs), memory cards, or floppy disks. The program codes may be compressed, for example, in a suitable format. When executed by a processing device, these codes cause the processing device to execute the various steps in the method described above. These program codes may be read from or written to one or more computer program products. These computer program products include program code carriers such as hard disks, compact disks (CDs), memory cards, or floppy disks. The program codes may be compressed, for example, in a suitable format. When these codes are executed by a computing and processing device, they cause the computing and processing device to execute the various steps of the above-described method for isolating a single-pole ground fault in a DC power distribution network.

[0186] The fifth embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for isolating a single-pole grounding fault in a DC distribution network according to any of the above embodiments is implemented.

[0187] Embodiment 6 of the present invention further provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by a computer, the computer executes the method for isolating a single-pole grounding fault in a DC distribution network as described in any of the above embodiments.

[0188] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0189] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0190] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0191] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0192] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the method of the present invention. The aforementioned storage medium includes various media that can store program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[0193] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for isolating a single-pole grounding fault in a DC distribution network, characterized in that: include: Acquiring operating parameters of each line head end of the DC distribution network, performing fault detection on each of the operating parameters, and obtaining corresponding fault detection results, multiple positive current mutation amounts, and multiple negative current mutation amounts; When the fault detection result is that a fault occurs in the DC distribution network, a quadratic fitting process is performed based on a preset quadratic function according to the positive current mutation amount and the negative current mutation amount corresponding to each of the line head ends to obtain a plurality of concavity and convexity coefficients; Single-pole grounding fault isolation is performed on the DC distribution network according to each of the concavity and convexity coefficients.

2. The method for isolating a single-pole grounding fault in a DC distribution network according to claim 1, wherein: The operating parameters include positive electrode current, negative electrode current, positive electrode voltage, and negative electrode voltage. The step of performing fault detection on each of the operating parameters to obtain corresponding fault detection results, multiple positive electrode current mutation amounts, and multiple negative electrode current mutation amounts includes: performing mutation calculations on each of the positive electrode currents, each of the negative electrode currents, each of the positive electrode voltages, and each of the negative electrode voltages, respectively, to obtain a plurality of positive electrode current mutation amounts, a plurality of negative electrode current mutation amounts, a plurality of positive electrode voltage mutation amounts, and a plurality of negative electrode voltage mutation amounts; Determine whether the absolute value of each of the positive electrode current mutation amounts, the absolute value of each of the negative electrode current mutation amounts, the absolute value of each of the positive electrode voltage mutation amounts, and the absolute value of each of the negative electrode voltage mutation amounts are all less than or equal to corresponding set values; If the absolute value of each of the positive current mutation amounts, the absolute value of each of the negative current mutation amounts, the absolute value of each of the positive voltage mutation amounts, and the absolute value of each of the negative voltage mutation amounts are all less than or equal to the corresponding set values, then the normal operation of the DC distribution network is determined as the corresponding fault detection result; If the absolute value of any of the positive current mutation amounts, the absolute value of any of the negative current mutation amounts, the absolute value of any of the positive voltage mutation amounts, or the absolute value of any of the negative voltage mutation amounts is greater than the corresponding set value, a fault in the DC distribution network is determined as the corresponding fault detection result.

3. The method for isolating a single-pole grounding fault in a DC distribution network according to claim 2, wherein: The step of performing mutation calculation on each of the positive electrode currents, each of the negative electrode currents, each of the positive electrode voltages, and each of the negative electrode voltages to obtain multiple positive electrode current mutation amounts, multiple negative electrode current mutation amounts, multiple positive electrode voltage mutation amounts, and multiple negative electrode voltage mutation amounts includes: performing difference processing on each of the positive electrode currents and the corresponding positive electrode reference current to obtain a plurality of positive electrode current mutation amounts; performing difference processing on each of the negative electrode currents and the corresponding negative electrode reference current to obtain a plurality of negative electrode current mutation amounts; performing difference processing on each of the positive electrode voltages and the corresponding positive electrode reference voltage to obtain a plurality of positive electrode voltage mutation amounts; Each of the negative electrode voltages is subjected to difference processing with a corresponding negative electrode reference voltage to obtain a plurality of negative electrode voltage mutation amounts.

4. The method for isolating a single-pole grounding fault in a DC distribution network according to claim 1, wherein: The step of performing quadratic fitting processing based on a preset quadratic function according to the positive current mutation amount and the negative current mutation amount corresponding to each of the line head ends to obtain a plurality of concavity and convexity coefficients includes: Obtaining historical positive current mutation data and historical negative current mutation data of each line head end, and solving a preset quadratic function using the historical positive current mutation data and positive current mutation amount corresponding to each line head end, to obtain multiple positive quadratic functions; The quadratic function is solved by respectively using the historical negative pole mutation data and the negative pole current mutation amount corresponding to the line head end to obtain multiple negative pole quadratic functions; Performing quadratic curve fitting on the corresponding positive electrode current mutation using each of the positive electrode quadratic functions to obtain a plurality of positive electrode quadratic fitting curves; Performing quadratic curve fitting on the corresponding negative electrode current mutation using each of the negative electrode quadratic functions to obtain a plurality of negative electrode quadratic fitting curves; The positive quadratic fitting curve and the negative quadratic curve corresponding to each of the line head ends are respectively subjected to curvature determination processing to obtain a plurality of concavity and convexity coefficients.

5. The method for isolating a single-pole grounding fault in a DC distribution network according to claim 4, wherein: The step of performing curvature determination processing on the positive quadratic fitting curve and the negative quadratic curve corresponding to each of the line head ends to obtain a plurality of concavity and convexity coefficients includes: performing a second-order derivative operation on each of the positive electrode quadratic fitting curves to obtain a plurality of positive electrode second-order derivatives; performing a second-order derivative operation on each of the negative electrode quadratic fitting curves to obtain a plurality of negative electrode second-order derivatives; The positive second-order derivative and the negative second-order derivative corresponding to each of the line head ends are multiplied to obtain a plurality of concavity and convexity coefficients.

6. The method for isolating a single-pole grounding fault in a DC distribution network according to claim 1, wherein: The step of isolating a single-pole grounding fault in the DC distribution network according to each of the concavity and convexity coefficients includes: Determining whether each of the concavity and convexity coefficients is less than a preset action threshold; When the concavity-convexity coefficient is less than the action threshold, the upstream protection measuring point corresponding to the concavity-convexity coefficient is determined as the measuring point to be analyzed; Obtaining the zero-mode voltage of each of the measurement points to be analyzed, and determining whether the absolute value of each of the zero-mode voltages is greater than a preset voltage setting value; When the absolute value of the zero-mode voltage is greater than the voltage setting value, the to-be-analyzed measuring point associated with the zero-mode voltage is determined as a target measuring point; Based on the preset action delay, single-pole grounding fault isolation is performed on each target measuring point in the DC distribution network.

7. A DC distribution network single-pole grounding fault isolation system, characterized in that: include: An acquisition module is used to obtain operating parameters of the headend of each line of the DC distribution network, perform fault detection on each of the operating parameters, and obtain corresponding fault detection results, multiple positive current mutation amounts, and multiple negative current mutation amounts; an analysis module configured to, when the fault detection result indicates a fault in the DC distribution network, perform quadratic fitting processing based on a preset quadratic function on the positive current mutation amount and the negative current mutation amount corresponding to each of the line head ends to obtain a plurality of concavity and convexity coefficients; An isolation module is used to isolate single-pole grounding faults in the DC distribution network according to each of the concavity and convexity coefficients.

8. An electronic device, characterized in that: The method comprises a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of the method for isolating a single-pole grounding fault in a DC distribution network according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed, the method for isolating a single-pole grounding fault in a DC distribution network according to any one of claims 1 to 6 is implemented.

10. A computer program product, characterized in that The computer program product includes a computer program stored on a non-transitory computer-readable storage medium, wherein the computer program includes program instructions. When the program instructions are executed by a computer, the computer is caused to execute the method for isolating a single-pole grounding fault in a DC distribution network according to any one of claims 1 to 6.

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