Multi-point fault detection method and protection system for regional protection of power distribution network

Abstract

The invention discloses a multipoint fault detection method and protection system for power distribution network area protection, and belongs to the technical field of power distribution network fault protection. The fault detection method comprises the following steps: determining a fault area, and obtaining fault characteristic parameters of the fault area; judging whether the fault area starts an area protection process or not according to the fault characteristic parameters; if the area protection process is started, direction values of neutral point zero-sequence current in the fault area and zero-sequence current at the head end of each line are calculated; constructing observed values of the current value and the current direction according to the current threshold value and the direction value; based on mixed integer linear programming, establishing a fault detection model which takes the minimum error between an observed value and a predicted value as a target function and takes zero-sequence current and three-phase current area protection logic as constraint conditions; and solving the fault detection model, and obtaining the fault line of the fault area from the optimal solution. And safety protection is carried out after the fault line is obtained. Accuracy and reliability of relay power grid protection can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network fault protection, and in particular to a multi-point fault detection method and protection system for regional protection of a distribution network. Background Art

[0002] With the continuous expansion of distribution network coverage, the high penetration of new energy sources, and the large-scale integration of nonlinear loads, system power flows are exhibiting dynamic fluctuations, and fault characteristics have fundamentally changed compared to traditional power grids. As a result, the three-stage current protection mechanism based on fixed thresholds may not be able to adapt to new operational requirements, posing a potential risk to the stable operation and quality of the power supply system. Against this backdrop, regional protection technology has gradually matured. Leveraging modern communication architectures, this technology integrates data such as switchgear status and protection device responses to construct a global fault identification and isolation decision-making system. It is worth noting that sections of long-serving three-core armored cables may experience degradation of their main insulation, a potential that is often difficult to detect under normal operating conditions. When a single-phase ground fault occurs in the system, the potential of the non-fault phase rises sharply to the line voltage level. This sudden voltage surge can trigger a potential insulation breakdown at a potential weak point, leading to a unique situation where multiple cable sections fail in succession. Existing regional protection systems, due to the inherent limitations of their protection criteria, are prone to disrupting the protection logic when responding to such concurrent multi-point faults, causing regional protection devices to fail or malfunction. At the same time, this technology is highly dependent on the information collection system. In actual operation, channel interference and data collection equipment failures often lead to information transmission loss or signal distortion. These abnormal data can mislead the protection decision-making module and significantly reduce the reliability of the protection system's action. Therefore, how to reliably handle multiple simultaneous faults and effectively improve the fault tolerance of regional protection are difficult problems that need to be solved in distribution network relay protection. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a multi-point fault detection method and protection system for distribution network area protection, so as to solve the technical problems that traditional area protection cannot handle the situation where multiple points fail simultaneously and is limited by data accuracy.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0005] In a first aspect, the present invention provides a multi-point fault detection method for regional protection of a distribution network, comprising:

[0006] Determine the protection area where the fault occurs and record it as the fault area, and obtain fault characteristic parameters of the fault area;

[0007] Determine whether to initiate a regional protection process for the fault area according to the fault characteristic parameters;

[0008] If the regional protection process is started, the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area are calculated;

[0009] constructing observation values of the current value and the current direction according to the current threshold value and the direction value;

[0010] Based on mixed integer linear programming, a fault detection model is established with the minimum error between the observed value and its predicted value as the objective function and the zero-sequence current and three-phase current area protection logic as the constraint conditions;

[0011] The fault detection model is solved to obtain the fault line in the fault area from the optimal solution.

[0012] Optionally, the protection area is constructed with the feeder of the primary busbar of the distribution network system as a basic unit, and each protection area includes the feeder and all downstream lines thereof.

[0013] Optionally, judging whether to initiate a regional protection process for the fault area according to the fault characteristic parameters includes:

[0014] If the fault characteristic parameters meet the zero-sequence current start criterion or the phase current start criterion, the regional protection process is started; the zero-sequence current start criterion is:

[0015]

[0016]

[0017] Where, is the zero-sequence current in the fault area, is the zero-sequence starting current, is the current of the first-end capacitor in the fault area, Real-time output of renewable energy when it fails, is the line load of the renewable energy access line, is the coefficient parameter;

[0018] The phase current starting criterion is:

[0019]

[0020]

[0021] Where, is the phase current of any line in the fault area, is the phase starting current, is the maximum load current corresponding to the phase current, is the coefficient parameter, is the output inflection point value of renewable energy, is the slope factor.

[0022] Optionally, calculating the direction values of the neutral point zero-sequence current and the head-end zero-sequence current of each line in the fault area includes:

[0023] Determine the time between the onset of the fault and the first zero crossing of the zero-sequence current , calculate the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area at each moment:

[0024]

[0025]

[0026] Where, for The direction value and instantaneous value of the neutral point zero sequence current at time, For the In the fault area Lines in The direction value and instantaneous value of the zero-sequence current at the head end of the line at that moment;

[0027] When there are multiple consecutive moment direction values If they are equal, use it as the direction value ; When there are multiple consecutive moment direction values If they are equal, use it as the direction value .

[0028] Optionally, constructing the observation value of the current value and the current direction according to the current threshold and the direction value includes:

[0029] Set the current threshold and construct the current value observation binary decision variable array based on the three-phase current at the head end of all lines in the fault area :

[0030]

[0031] Where, For the The current value observation binary decision variable array corresponding to the fault area, For the In the fault area The current value corresponding to each line is observed as a binary decision variable, For the Total number of lines in the fault area;

[0032] Jordi If any phase of the three-phase current at the head end of a line exceeds the current threshold, the If a line or its downstream line fails, ,otherwise, ;

[0033] The direction value of the neutral point zero sequence current As a benchmark, a current direction observation binary decision variable array is constructed according to the direction value of the zero-sequence current in the fault area. :

[0034]

[0035] Where, For the The current direction observation binary decision variable array corresponding to the fault area, For the In the fault area The current direction corresponding to each line is observed as a binary decision variable;

[0036] Jordi The direction value of the zero-sequence current at the beginning of the line Direction value of neutral point zero sequence current Same, then ,otherwise, .

[0037] Optionally, the objective function is:

[0038]

[0039]

[0040]

[0041] Where, For the The objective function corresponding to the fault area is: For the In the fault area The current value observation binary decision variable and the current direction observation binary decision variable corresponding to each line are for The predicted value of is the error term, For the The total number of lines in the fault area.

[0042] Optionally, the constraints include:

[0043] At least one line in the fault area is in fault state:

[0044]

[0045] Where, For the In the fault area The operating status of each line, when the operating status is fault, ,otherwise ;

[0046] Three-phase current zone protection logic, define the In the fault area The relationship between the three-phase current and the current threshold of each line is , if In the fault area If the three-phase current of each line is greater than the current threshold, ,otherwise, ; The specific expression is:

[0047]

[0048] Zero sequence current zone protection logic, definition In the fault area The direction of the zero sequence current of each line is , if In the fault area The direction of the zero sequence current of each line is from the load to the busbar, then ,otherwise, ; The specific expression is:

[0049]

[0050] Where, is the logical OR.

[0051] In a second aspect, the present invention provides a multi-point fault detection device for regional protection of a distribution network, comprising:

[0052] a fault area determination module configured to determine a protection area where a fault occurs and record it as a fault area, and obtain fault characteristic parameters of the fault area;

[0053] a protection process starting module, configured to determine whether to start a regional protection process for the fault area according to the fault characteristic parameters;

[0054] a current parameter calculation module configured to calculate the direction value of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area if the regional protection process is started;

[0055] an observation value construction module, configured to construct observation values of the current value and the current direction according to the current threshold and the direction value;

[0056] a detection model building module configured to establish a fault detection model based on mixed integer linear programming, with minimizing the error between the observed value and the predicted value as the objective function and with zero-sequence current and three-phase current area protection logic as constraints;

[0057] The fault line detection module is configured to solve the fault detection model and obtain the fault line in the fault area from the optimal solution.

[0058] Optionally, calculating the direction values of the neutral point zero-sequence current and the head-end zero-sequence current of each line in the fault area includes:

[0059] Determine the time between the onset of the fault and the first zero crossing of the zero-sequence current , calculate the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area at each moment:

[0060]

[0061]

[0062] Where, for The direction value and instantaneous value of the neutral point zero sequence current at time, For the In the fault area Lines in The direction value and instantaneous value of the zero-sequence current at the head end of the line at that moment;

[0063] When there are multiple consecutive moment direction values If they are equal, use it as the direction value ; When there are multiple consecutive moment direction values If they are equal, use it as the direction value .

[0064] Optionally, constructing the observation value of the current value and the current direction according to the current threshold and the direction value includes:

[0065] Set the current threshold and construct the current value observation binary decision variable array based on the three-phase current at the head end of all lines in the fault area :

[0066]

[0067] Where, For the The current value observation binary decision variable array corresponding to the fault area, For the In the fault area The current value corresponding to each line is observed as a binary decision variable, For the Total number of lines in the fault area;

[0068] Jordi If any phase of the three-phase current at the head end of a line exceeds the current threshold, the If a line or its downstream line fails, ,otherwise, ;

[0069] The direction value of the neutral point zero sequence current As a benchmark, a current direction observation binary decision variable array is constructed according to the direction value of the zero-sequence current in the fault area. :

[0070]

[0071] Where, For the The current direction observation binary decision variable array corresponding to the fault area, For the In the fault area The current direction corresponding to each line is observed as a binary decision variable;

[0072] Jordi The direction value of the zero-sequence current at the beginning of the line Direction value of neutral point zero sequence current Same, then ,otherwise, .

[0073] In a third aspect, the present invention provides an electronic device, including a processor and a storage medium;

[0074] The storage medium is used to store instructions;

[0075] The processor is configured to operate according to the instructions to execute the steps of the above method.

[0076] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the above method when executed by a processor.

[0077] In a fifth aspect, the present invention provides a computer program product, comprising a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0078] In a sixth aspect, the present invention provides a multi-point fault protection system for regional protection of a distribution network, comprising:

[0079] Distribution automation terminals are installed at the head end of each line within the protection area;

[0080] A regional decision unit is provided within the protection area and is electrically connected to each of the distribution automation terminals. When a fault occurs, all the distribution automation terminals within the protection area collect fault waveforms and transmit them to the regional decision unit via a link. The regional decision unit uses the above-mentioned fault detection method to obtain the fault line and generate a relay protection instruction.

[0081] The relay protection device is set on each line in the protection area and receives and executes the relay protection instructions sent by the regional decision unit.

[0082] Optionally, the multi-point fault protection system further includes a system monitoring center, which is electrically connected to each of the regional decision-making units and is used to display fault detection and processing results.

[0083] Compared with the prior art, the present invention has the following beneficial effects:

[0084] The present invention provides a multi-point fault detection method and protection system for distribution network regional protection. Based on mixed-integer linear programming, this method establishes a fault detection model with minimizing the error between observed values and their predicted values as the objective function and using zero-sequence current and three-phase current regional protection logic as constraints. Line fault detection is performed based on the fault detection model, and accurate relay protection is implemented after line fault detection. This method solves the problems of protection logic confusion and protection refusal or misoperation caused by erroneous data that may occur in traditional regional protection systems when facing multiple simultaneous faults, thereby meeting the requirements for relay protection sensitivity and reliability. In practical applications, it is not necessary to centrally process all fault information in the distribution network, greatly reducing the computational complexity of the distribution network regional protection algorithm and improving practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 1 is a flow chart of a multi-point fault detection method for regional protection of a distribution network provided by an embodiment of the present invention;

[0086] Figure 2 1 is a topological diagram of a low-resistance grounded distribution network including an IIDG provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0087] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0088] Example 1:

[0089] like Figure 1 As shown, an embodiment of the present invention provides a multi-point fault detection method for regional protection of a distribution network, comprising the following steps:

[0090] Step S1: determine the protection area where the fault occurs and record it as the fault area, and obtain the fault characteristic parameters of the fault area.

[0091] Specifically in this embodiment, the protection area is constructed with the feeder of the primary busbar of the distribution network system as a basic unit, and each protection area includes the feeder and all downstream lines thereof.

[0092] Step S2: Determine whether to start a regional protection process for the fault area based on the fault characteristic parameters.

[0093] Specifically, in this embodiment, if the fault characteristic parameter satisfies the zero-sequence current starting criterion or the phase current starting criterion, the regional protection process is started.

[0094] Among them, the zero-sequence current starting criterion is:

[0095]

[0096]

[0097] Where, is the zero-sequence current in the fault area, is the zero-sequence starting current, is the current of the first-end capacitor in the fault area, Real-time output of renewable energy when it fails, is the line load of the renewable energy access line, is the coefficient parameter;

[0098] The phase current starting criterion is:

[0099]

[0100]

[0101] Where, is the phase current of any line in the fault area, is the phase starting current, is the maximum load current corresponding to the phase current, is the coefficient parameter, is the output inflection point value of renewable energy, is the slope factor.

[0102] Step S3: If the regional protection process is started, the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area are calculated.

[0103] First All lines in the fault area are taken as elements to construct a line set , with the first In the fault area The line and all the lines downstream of it are composed of the elements A line and its downstream line collection .

[0104] Specifically in this embodiment, calculating the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area includes:

[0105] Determine the time between the onset of the fault and the first zero crossing of the zero-sequence current , calculate the direction value of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area at each moment:

[0106]

[0107]

[0108] Where, for The direction value and instantaneous value of the neutral point zero sequence current at time, For the In the fault area Lines in The direction value and instantaneous value of the zero-sequence current at the head end of the line at that moment;

[0109] When there are multiple consecutive moment direction values If they are equal, use it as the direction value ; When there are multiple consecutive moment direction values If they are equal, use it as the direction value .like , when the direction value for 5 consecutive moments Equality / Direction Value When they are equal, we get the direction value / Direction value .

[0110] Step S4: construct observation values of the current value and the current direction according to the current threshold and the direction value.

[0111] Set the current threshold and construct the current value observation binary decision variable array based on the three-phase current at the head end of all lines in the fault area :

[0112]

[0113] Where, For the The current value observation binary decision variable array corresponding to the fault area, For the In the fault area The current value corresponding to each line is observed as a binary decision variable, For the Total number of lines in the fault area;

[0114] Jordi If any phase of the three-phase current at the head end of a line exceeds the current threshold, the If a line or its downstream line fails, ,otherwise, ;

[0115] The direction value of the neutral point zero sequence current As a benchmark, the current direction observation binary decision variable array is constructed according to the direction value of the zero-sequence current in the fault area. :

[0116]

[0117] Where, For the The current direction observation binary decision variable array corresponding to the fault area, For the In the fault area The current direction corresponding to each line is observed as a binary decision variable;

[0118] Jordi The direction value of the zero-sequence current at the beginning of the line Direction value of neutral point zero sequence current Same, then ,otherwise, .

[0119] Step S5: Based on mixed integer linear programming, a fault detection model is established with the minimum error between the observed value and its predicted value as the objective function and the zero-sequence current and three-phase current regional protection logic as the constraint conditions.

[0120] Mixed-integer linear programming (MILP) refers to mathematical programming problems in which both the objective function and constraints are linear, and some decision variables are restricted to integers. Specifically, the constraints support equality and inequality constraints, and the variables can be 0-1, integer, or real. MILP is used to find the optimal solution and value of a linear objective function within a given feasible region under linear constraints.

[0121] The objective function is to minimize the error between the observed value and its predicted value:

[0122]

[0123]

[0124]

[0125] Where, For the The objective function corresponding to the fault area is: For the In the fault area The current value observation binary decision variable and the current direction observation binary decision variable corresponding to each line are for The predicted value of is the error term, For the The total number of lines in the fault area.

[0126] The zero-sequence current and three-phase current zone protection logic are constrained:

[0127] At least one line in the fault area is in fault state:

[0128]

[0129] Where, For the In the fault area The operating status of each line, when the operating status is fault, ,otherwise ;

[0130] Three-phase current zone protection logic, define the In the fault area The relationship between the three-phase current and the current threshold of each line is , if In the fault area If the three-phase current of each line is greater than the current threshold, ,otherwise, ; The specific expression is:

[0131]

[0132] Zero sequence current zone protection logic, definition In the fault area The direction of the zero sequence current of each line is , if In the fault area The direction of the zero sequence current of each line is from the load to the busbar, then ,otherwise, ; The specific expression is:

[0133]

[0134] Where, is the logical OR.

[0135] Step S6: Solve the fault detection model and obtain the fault line in the fault area from the optimal solution.

[0136] In the objective function and As the intermediate variable, the fault detection model is solved based on the optimization solver to obtain:

[0137]

[0138]

[0139]

[0140]

[0141]

[0142] From The running status array corresponding to the lines in the fault area In this paper, the number and location of faulty lines can be obtained, thereby realizing regional protection.

[0143] In order to verify the effectiveness of the proposed regional fault detection scheme, the following Figure 2 The low-resistance grounded distribution network with IIDGs is shown in the figure. The neutral point low-resistance of the distribution network is 10Ω. The ratios and capacities of the main transformer and IIDG grid-connected transformer are shown in the figure. All lines are equipped with distribution automation terminals. The lines are all YJV22-6 / 10kV-3*70mm2, with a unit zero-sequence ground capacitance parameter of C0 = 124.28×10-9F / km. The PQ-controlled photovoltaic model is packaged as an IIDG module T-connected to the line, and each outgoing line is connected to a constant impedance load model of 1MW+0.1MVar per phase. To evaluate the effectiveness of the proposed method, two single-phase ground faults were set in the simulation system as shown in the figure. It was assumed that the three-phase current data of FI21 uploaded to the regional decision center was excessive due to equipment failure, FI13 was lost due to equipment failure, and the zero-sequence current of FI11 was lost due to communication problems. The proposed regional protection method was used to calculate the regional protection for the above fault scenario, and the results are as follows:

[0144] The observed values are as follows:

[0145]

[0146] The results of model solution are as follows:

[0147]

[0148]

[0149]

[0150]

[0151]

[0152] According to the running status array Given the value of , the method successfully identifies the faulty sections L25 and L28. In addition, the method also detects the wrong three-phase current and the missing zero-sequence current at this time. , The assumed true state of the above abnormal data is given.

[0153] It can be seen that the proposed method can effectively solve the logical dilemma of traditional regional protection methods when facing multiple faults, and can reliably perform regional protection in the presence of data anomalies, verifying the effectiveness of the proposed protection scheme. In summary, the multi-point fault detection method for distribution network regional protection with high fault tolerance proposed in this invention solves the protection logic confusion problem that may be caused by traditional regional protection when facing multiple simultaneous faults, as well as the protection refusal and malfunction problem caused by erroneous data, and meets the requirements for the sensitivity and reliability of distribution network relay protection.

[0154] Example 2:

[0155] An embodiment of the present invention provides a multi-point fault detection device for regional protection of a distribution network, comprising:

[0156] a fault area determination module configured to determine a protection area where a fault occurs and record it as a fault area, and obtain fault characteristic parameters of the fault area;

[0157] A protection process starting module is configured to determine whether to start a regional protection process in the fault area according to the fault characteristic parameters;

[0158] The current parameter calculation module is configured to calculate the direction value of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area if the regional protection process is started;

[0159] An observation value construction module is configured to construct observation values of current value and current direction according to a current threshold value and a direction value;

[0160] A detection model building module is configured to establish a fault detection model based on mixed integer linear programming, with the objective function being to minimize the error between the observed value and its predicted value, and with the zero-sequence current and three-phase current area protection logic as constraints;

[0161] The fault line detection module is configured to solve the fault detection model and obtain the fault line in the fault area from the optimal solution.

[0162] Specifically, the calculation of the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area includes:

[0163] Determine the time between the onset of the fault and the first zero crossing of the zero-sequence current , calculate the direction value of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area at each moment:

[0164]

[0165]

[0166] Where, for The direction value and instantaneous value of the neutral point zero sequence current at time, For the In the fault area Lines in The direction value and instantaneous value of the zero-sequence current at the head end of the line at that moment;

[0167] When there are multiple consecutive moment direction values If they are equal, use it as the direction value ; When there are multiple consecutive moment direction values If they are equal, use it as the direction value .

[0168] The observation values of current value and current direction are constructed based on the current threshold and direction value, including:

[0169] Set the current threshold and construct the current value observation binary decision variable array based on the three-phase current at the head end of all lines in the fault area :

[0170]

[0171] Where, For the The current value observation binary decision variable array corresponding to the fault area, For the In the fault area The current value corresponding to each line is observed as a binary decision variable, For the Total number of lines in the fault area;

[0172] Jordi If any phase of the three-phase current at the head end of a line exceeds the current threshold, the If a line or its downstream line fails, ,otherwise, ;

[0173] The direction value of the neutral point zero sequence current As a benchmark, the current direction observation binary decision variable array is constructed according to the direction value of the zero-sequence current in the fault area. :

[0174]

[0175] Where, For the The current direction observation binary decision variable array corresponding to the fault area, For the In the fault area The current direction corresponding to each line is observed as a binary decision variable;

[0176] Jordi The direction value of the zero-sequence current at the beginning of the line Direction value of neutral point zero sequence current Same, then ,otherwise, .

[0177] Example 3:

[0178] Based on the fault detection method provided in the first embodiment, the embodiment of the present invention provides an electronic device, including a processor and a storage medium;

[0179] The storage medium is used to store instructions;

[0180] The processor is configured to operate according to the instructions to execute the steps of the above method.

[0181] Example 4:

[0182] Based on the fault detection method provided in the first embodiment, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the steps of the above method are implemented.

[0183] Embodiment 5:

[0184] Based on the fault detection method provided in the first embodiment, an embodiment of the present invention provides a computer program product, including a computer program / instruction, which implements the steps of the above method when executed by a processor.

[0185] Example 6:

[0186] Based on the fault detection method provided in Example 1, this embodiment of the present invention provides a multi-point fault protection system for regional protection of a distribution network, including:

[0187] Distribution automation terminals are installed at the head end of each line within the protection area;

[0188] The regional decision-making unit is located within the protection area and is electrically connected to each distribution automation terminal. When a fault occurs, all distribution automation terminals within the protection area collect fault waveforms and transmit them to the regional decision-making unit via a link. The regional decision-making unit uses the above fault detection method to obtain the fault line and generate relay protection instructions.

[0189] Relay protection devices are installed on each line within the protection area and receive and execute relay protection instructions sent by the regional decision-making unit;

[0190] The system monitoring center is electrically connected to each regional decision-making unit and is used to display fault detection and processing results.

[0191] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0192] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0193] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0194] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0195] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multi-point fault detection method for regional protection of a distribution network, characterized in that: include: Determine the protection area where the fault occurs and record it as the fault area, and obtain fault characteristic parameters of the fault area; Determine whether to initiate a regional protection process for the fault area according to the fault characteristic parameters; If the regional protection process is started, the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area are calculated; constructing observation values of the current value and the current direction according to the current threshold value and the direction value; Based on mixed integer linear programming, a fault detection model is established with the minimum error between the observed value and its predicted value as the objective function and the zero-sequence current and three-phase current area protection logic as the constraint conditions; The fault detection model is solved to obtain the fault line in the fault area from the optimal solution.

2. The multi-point fault detection method for distribution network area protection according to claim 1, characterized in that: The protection area is constructed with the feeder of the primary busbar of the distribution network system as a basic unit, and each protection area includes the feeder and all downstream lines thereof.

3. The multi-point fault detection method for distribution network area protection according to claim 1, characterized in that: The process of determining whether to start regional protection for the faulty area according to the fault characteristic parameters includes: If the fault characteristic parameters meet the zero-sequence current start criterion or the phase current start criterion, the regional protection process is started; the zero-sequence current start criterion is: Where, is the zero-sequence current in the fault area, is the zero-sequence starting current, is the current of the first-end capacitor in the fault area, Real-time output of renewable energy when it fails, is the line load of the renewable energy access line, is the coefficient parameter; The phase current starting criterion is: Where, is the phase current of any line in the fault area, is the phase starting current, is the maximum load current corresponding to the phase current, is the coefficient parameter, is the output inflection point value of renewable energy, is the slope factor.

4. The multi-point fault detection method for distribution network area protection according to claim 1, characterized in that: Calculating the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area includes: Determine the time between the onset of the fault and the first zero crossing of the zero-sequence current , calculate the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area at each moment: Where, for The direction value and instantaneous value of the neutral point zero sequence current at time, For the In the fault area Lines in The direction value and instantaneous value of the zero-sequence current at the head end of the line at that moment; When there are multiple consecutive moment direction values If they are equal, use it as the direction value ; When there are multiple consecutive moment direction values If they are equal, use it as the direction value .

5. The multi-point fault detection method for distribution network area protection according to claim 1, characterized in that: The step of constructing the observation value of the current value and the current direction according to the current threshold value and the direction value includes: Set the current threshold and construct the current value observation binary decision variable array based on the three-phase current at the head end of all lines in the fault area : Where, For the The current value observation binary decision variable array corresponding to the fault area, For the In the fault area The current value corresponding to each line is observed as a binary decision variable, For the Total number of lines in the fault area; Jordi If any phase of the three-phase current at the head end of a line exceeds the current threshold, the If a line or its downstream line fails, ,otherwise, ; The direction value of the neutral point zero sequence current As a benchmark, a current direction observation binary decision variable array is constructed according to the direction value of the zero-sequence current in the fault area. : Where, For the The current direction observation binary decision variable array corresponding to the fault area, For the In the fault area The current direction corresponding to each line is observed as a binary decision variable; Jordi The direction value of the zero-sequence current at the beginning of the line Direction value of neutral point zero sequence current Same, then ,otherwise, .

6. The multi-point fault detection method for distribution network area protection according to claim 1, characterized in that: The objective function is: Where, For the The objective function corresponding to the fault area is: For the In the fault area The current value observation binary decision variable and the current direction observation binary decision variable corresponding to each line are for The predicted value of is the error term, For the The total number of lines in the fault area.

7. The multi-point fault detection method for distribution network area protection according to claim 6, characterized in that: The constraints include: At least one line in the fault area is in fault state: Where, For the In the fault area The operating status of each line, when the operating status is fault, ,otherwise ; Three-phase current zone protection logic, define the In the fault area The relationship between the three-phase current and the current threshold of each line is , if In the fault area If the three-phase current of each line is greater than the current threshold, ,otherwise, ; The specific expression is: Zero sequence current zone protection logic, definition In the fault area The direction of the zero sequence current of each line is , if In the fault area The direction of the zero sequence current of each line is from the load to the busbar, then ,otherwise, ; The specific expression is: Where, is the logical OR.

8. A multi-point fault detection device for regional protection of a distribution network, characterized in that: include: a fault area determination module configured to determine a protection area where a fault occurs and record it as a fault area, and obtain fault characteristic parameters of the fault area; a protection process starting module, configured to determine whether to start a regional protection process for the fault area according to the fault characteristic parameters; a current parameter calculation module configured to calculate the direction value of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area if the regional protection process is started; an observation value construction module, configured to construct observation values of the current value and the current direction according to the current threshold and the direction value; a detection model building module configured to establish a fault detection model based on mixed integer linear programming, with minimizing the error between the observed value and the predicted value as the objective function and with zero-sequence current and three-phase current area protection logic as constraints; The fault line detection module is configured to solve the fault detection model and obtain the fault line in the fault area from the optimal solution.

9. The multi-point fault detection device for regional protection of a distribution network according to claim 8, characterized in that: Calculating the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area includes: Determine the time between the onset of the fault and the first zero crossing of the zero-sequence current , calculate the direction values of the neutral point zero-sequence current and the zero-sequence current at the head end of each line in the fault area at each moment: Where, for The direction value and instantaneous value of the neutral point zero sequence current at time, For the In the fault area Lines in The direction value and instantaneous value of the zero-sequence current at the head end of the line at that moment; When there are multiple consecutive moment direction values If they are equal, use it as the direction value ; When there are multiple consecutive moment direction values If they are equal, use it as the direction value .

10. The multi-point fault detection device for regional protection of distribution network according to claim 8, characterized in that: The step of constructing the observation value of the current value and the current direction according to the current threshold value and the direction value includes: Set the current threshold and construct the current value observation binary decision variable array based on the three-phase current at the head end of all lines in the fault area : Where, For the The current value observation binary decision variable array corresponding to the fault area, For the In the fault area The current value corresponding to each line is observed as a binary decision variable, For the Total number of lines in the fault area; Jordi If any phase of the three-phase current at the head end of a line exceeds the current threshold, the If a line or its downstream line fails, ,otherwise, ; The direction value of the neutral point zero sequence current As a benchmark, a current direction observation binary decision variable array is constructed according to the direction value of the zero-sequence current in the fault area. : Where, For the The current direction observation binary decision variable array corresponding to the fault area, For the In the fault area The current direction corresponding to each line is observed as a binary decision variable; Jordi The direction value of the zero-sequence current at the beginning of the line Direction value of neutral point zero sequence current Same, then ,otherwise, .

11. An electronic device, characterized in that: including processors and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 7.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

13. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

14. A multi-point fault protection system for regional protection of a distribution network, characterized in that: include: Distribution automation terminals are installed at the head end of each line within the protection area; A regional decision unit is provided within the protection area and is electrically connected to each of the distribution automation terminals; when a fault occurs, all the distribution automation terminals within the protection area collect fault waveforms and transmit them to the regional decision unit via a link; the regional decision unit uses the fault detection method according to any one of claims 1 to 7 to obtain the fault line and generate a relay protection instruction; The relay protection device is set on each line in the protection area and receives and executes the relay protection instructions sent by the regional decision unit.

15. The multi-point fault protection system for distribution network area protection according to claim 14, characterized in that: The multi-point fault protection system further includes a system monitoring center, which is electrically connected to each of the regional decision-making units and is used to display fault detection and processing results.

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