Distribution line protection method, device and electronic equipment

Abstract

The present application relates to a distribution line protection method, device and electronic equipment, and to the field of circuit protection technology. The method includes: obtaining a voltage waveform data array on both sides of the distribution line, and a current waveform data array on both sides of the distribution line; filtering the current waveform data array to obtain a filtered current waveform data array; determining the voltage qualification rate corresponding to the voltage waveform data array, and determining the waveform similarity corresponding to the filtered current waveform data array when the voltage qualification rate at both ends of the distribution line meets the discrimination range; determining the section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold, and determining the protection strategy of the distribution line based on the section discrimination criterion and the overcurrent protection criterion of the distribution line; the discrimination threshold is determined after simulating the waveform similarity of the distribution line under different fault conditions based on the distribution network simulation model. The use of this method can improve the safety of the distribution line.

Description

Technical Field

[0001] The present application relates to the field of circuit protection technology, and in particular to a distribution line protection method, device, electronic device, storage medium and computer program product. Background Art

[0002] With the access of distributed power sources such as photovoltaic, wind power, and small hydropower to the distribution network, it brings huge technical challenges to the line protection of the distribution network. The auxiliary and external effects of distributed power sources will cause the protection range of the three-stage current protection of the distribution network to be extended and shortened, thereby reducing the reliability of current protection and causing protection misoperation and refusal to operate.

[0003] In the related technology, current differential protection can solve the problem of protection failure in the distribution network. However, due to the access of distributed power supply branches, the current differential protection loses its application premise, resulting in the failure of the three-stage overcurrent protection of the medium-voltage distribution line in the scenario where distributed power supplies are widely accessed, making it impossible to identify medium-voltage distribution line faults, thereby reducing the safety of medium-voltage distribution lines. Summary of the invention

[0004] Based on this, it is necessary to provide a distribution line protection method, device, electronic device, computer-readable storage medium and computer program product that can improve the safety of medium-voltage distribution lines in response to the above-mentioned technical problems.

[0005] In a first aspect, the present application provides a distribution line protection method. The method comprises:

[0006] Acquire a voltage waveform data array on both sides of a distribution line, and a current waveform data array on both sides of the distribution line;

[0007] Performing filtering processing on the current waveform data array to obtain a filtered current waveform data array;

[0008] Determine the voltage qualification rate corresponding to the voltage waveform data array, and determine the waveform similarity corresponding to the filtered current waveform data array when the voltage qualification rates at both ends of the distribution line meet the discrimination range;

[0009] Based on the waveform similarity and the discrimination threshold, the section discrimination criterion of the distribution line is determined, and based on the section discrimination criterion and the overcurrent protection criterion of the distribution line, the protection strategy of the distribution line is determined; the discrimination threshold is determined after simulating the waveform similarity of the distribution line under different fault conditions based on a distribution network simulation model.

[0010] In one embodiment, filtering the current waveform data array to obtain a filtered current waveform data array includes:

[0011] Based on the cutoff frequency and the filter order, the first elements corresponding to the multi-phase electricity in the current waveform data array on both sides of the distribution line are calculated to obtain the filter values ​​corresponding to each of the first elements; the cutoff frequency is used to represent the lowest frequency allowed to pass in the signal;

[0012] The corresponding filtering values ​​in the multi-phase electricity are combined to obtain an array of filtered current waveform data on both sides of the distribution line.

[0013] In one embodiment, determining the voltage qualification rate corresponding to the voltage waveform data array includes:

[0014] For the voltage waveform data arrays at both sides of the power distribution line, determine the sum of squares of the second elements corresponding to the multi-phase electricity in the voltage waveform data arrays;

[0015] multiplying the number of the second elements by the square of the preset voltage value of the power distribution line to obtain a product value;

[0016] The quotient of the square sum and the product value is determined as the voltage qualification rate corresponding to the voltage waveform data array.

[0017] In one embodiment, the filtered current waveform data array includes a first side waveform array and a second side waveform array; when the voltage qualification rate at both ends of the distribution line meets the judgment range, determining the waveform similarity corresponding to the filtered current waveform data array includes:

[0018] If the qualified rate of any voltage at both ends of the distribution line is within the judgment range, for each phase of the multi-phase electricity, determine the first square sum of each third element in the first-side waveform array, the second square sum of each third element in the second-side waveform array, and the third square sum corresponding to the product of two third elements at the same position of the first-side waveform array and the second-side waveform array;

[0019] Performing two different primary operation processes on the first square sum, the second square sum, and the third square sum to obtain a first result and a second result;

[0020] The quotient of the first result and the second result is determined as each corresponding waveform similarity in the filtered current waveform data array.

[0021] In one embodiment, the method further comprises:

[0022] Determine preset distribution network data and distribution network structure diagram, wherein the distribution network structure diagram includes connected system power supply, distributed power supply, overhead line and load equipment; the distribution network data includes data corresponding to the system power supply, the distributed power supply, the overhead line and the load equipment;

[0023] The distribution network data and the distribution network structure diagram are simulated by the distribution network simulation model to determine the current waveform data corresponding to the two sides of the fault line and the two sides of the non-fault line under different fault conditions;

[0024] Based on the current waveform data, determining a first current waveform similarity coefficient array corresponding to the fault line and a second current waveform similarity coefficient array corresponding to the non-fault line;

[0025] A discrimination threshold is determined according to a maximum value in the first current waveform similarity coefficient array and a minimum value in the second current waveform similarity coefficient array.

[0026] In one embodiment, determining the section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold comprises:

[0027] If the waveform similarities of each item in the multi-phase electricity are greater than or equal to the discrimination threshold, it is determined that the distribution line has a fault;

[0028] If the waveform similarity of any one of the multi-phase electricity items is less than the discrimination threshold, it is determined that no fault occurs in the power distribution line.

[0029] In one embodiment, the protection strategy includes an instant tripping strategy, a delayed tripping strategy and a blocking protection strategy; the protection strategy of the distribution line is determined based on the section discrimination criterion and the overcurrent protection criterion of the distribution line, including:

[0030] If a fault occurs in the distribution line and any effective value of a current on both sides of the distribution line is greater than a preset threshold, an instant tripping strategy is determined as a protection strategy for the distribution line;

[0031] If a fault occurs in the distribution line, and the effective values ​​of the currents on both sides of the distribution line are both less than the preset threshold, determining the delayed tripping strategy as the protection strategy for the distribution line;

[0032] If the distribution line has not failed, and any effective value of the current on both sides of the distribution line is greater than the preset threshold, then determining the delayed tripping strategy as the protection strategy of the distribution line;

[0033] If the distribution line has not failed, and the effective values ​​of the currents on both sides of the distribution line are both less than the preset threshold, the blocking protection strategy is determined as the protection strategy for the distribution line.

[0034] In one embodiment, the method further comprises:

[0035] For the filtered voltage waveform data arrays at both sides of the distribution line, determine the sum of squares of the third elements corresponding to each phase of the multi-phase electricity in the filtered current waveform data array as the fourth square sum;

[0036] Based on the quotient of the fourth square sum and a preset value, the effective value of the current at both sides of the distribution line is determined.

[0037] In a second aspect, the present application also provides a distribution line protection device. The device comprises:

[0038] A data acquisition module, used to acquire a voltage waveform data array on both sides of a distribution line, and a current waveform data array on both sides of the distribution line;

[0039] A current filtering module, used for filtering the current waveform data array to obtain a filtered current waveform data array;

[0040] A similarity determination module, used to determine the voltage qualification rate corresponding to the voltage waveform data array, and determine the waveform similarity corresponding to the filtered current waveform data array when the voltage qualification rate at both ends of the distribution line meets the discrimination range;

[0041] A strategy determination module is used to determine the section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold, and to determine the protection strategy of the distribution line based on the section discrimination criterion and the overcurrent protection criterion of the distribution line; the discrimination threshold is determined after simulating the waveform similarity of the distribution line under different fault conditions based on a distribution network simulation model.

[0042] In a third aspect, the present application further provides an electronic device, wherein the electronic device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the method described in the first aspect are implemented.

[0043] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the method described in the first aspect are implemented.

[0044] In a fifth aspect, the present application further provides a computer program product, wherein the computer program product comprises a computer program, and when the computer program is executed by a processor, the steps of the method described in the first aspect are implemented.

[0045] The above-mentioned distribution line protection method, device, electronic device, storage medium and computer program product obtain the current waveform data array on both sides of the distribution line and filter the current waveform data array to obtain the filtered current waveform data array. And obtain the voltage waveform data array on both sides of the distribution line, determine the voltage qualification rate corresponding to the voltage waveform data array, and when it is determined that the voltage qualification rate at both ends of the distribution line meets the discrimination range, process the filtered current waveform data array to obtain the corresponding waveform similarity. The protection terminal determines the section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold. The section discrimination criterion enables the protection terminal to preliminarily judge whether the distribution line has a fault based on the waveform similarity. The protection terminal also determines the protection strategy for the distribution line based on the section discrimination criterion and the overcurrent protection criterion of the distribution line.

[0046] The above method can obtain the voltage and current on both sides of the distribution line, two-dimensional waveform data, and process the waveform data, thereby increasing the data dimension used to determine the protection strategy and improving the accuracy of determining the protection strategy. Afterwards, it is necessary to determine whether to protect the distribution line when the voltage qualification rate and waveform similarity corresponding to the voltage and current meet the judgment range and judgment criteria respectively. It can accurately identify and determine the prerequisites for executing the protection strategy, and comprehensively determine the specific protection strategy based on the section judgment criteria and overcurrent protection criteria to improve the safety of the distribution line. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 A diagram showing an application environment of a power distribution line protection method in an embodiment;

[0049] Figure 2 A schematic diagram of a flow chart of a power distribution line protection method in one embodiment;

[0050] Figure 3 A schematic diagram of a flow chart of a step of determining a discrimination threshold in one embodiment;

[0051] Figure 4is a flow chart of a distribution line protection method in another embodiment;

[0052] Figure 5 A structural diagram of a 10KV distribution network in an embodiment;

[0053] Figure 6 is a schematic diagram of a line similarity coefficient in one embodiment;

[0054] Figure 7 A schematic diagram of a line current waveform when a distributed power source is not connected and fails in one embodiment;

[0055] Figure 8 A schematic diagram of a line current waveform when a distributed power source is connected and fails in one embodiment;

[0056] Fig. 9 is a structural block diagram of a power distribution line protection device in one embodiment;

[0057] Fig.10 FIG. 4 is a diagram showing the internal structure of an electronic device in one embodiment. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0059] The power distribution line protection method provided in the embodiment of the present application can be applied to Figure 1In the application environment shown. Among them, the protection terminal 102 communicates with the processor 104 and the distribution line 106 respectively through the communication network, and the protection terminal 102 can measure both sides of the distribution line to obtain the required voltage waveform data array and current waveform data array. The protection terminal 102 can input the acquired data into the processor 104 for processing. The protection terminal 102 can filter the current waveform data array through the processor 104 to obtain the filtered current waveform data array. The protection terminal 102 can determine the voltage qualification rate corresponding to the voltage waveform data array through the processor 104, and determine the waveform similarity corresponding to the filtered current waveform data array when the voltage qualification rate at both ends of the distribution line meets the discrimination range. The protection terminal 102 can determine the section discrimination criterion of the distribution line according to the waveform similarity and the preset discrimination threshold, and determine the protection strategy of the distribution line according to the section discrimination criterion and the overcurrent protection criterion of the distribution line, and execute the protection strategy, thereby protecting the distribution line. The processor 104 can be integrated on the protection terminal 102, or it can be placed on the cloud or other network servers. The protection terminal 102 may be, but is not limited to, various personal computers, laptop computers, and control devices.

[0060] In an exemplary embodiment, Figure 2 As shown, a method is provided, which is applied to Figure 1 Taking the protection terminal 102 in the example as an example, the method includes the following steps S202 to S208. Among them:

[0061] Step S202, obtaining a voltage waveform data array on both sides of the distribution line, and a current waveform data array on both sides of the distribution line.

[0062] Specifically, the protection terminal, also called the protection device, can collect the voltage and current waveform data at both ends of the distribution line in real time after a distribution line fault, and save the voltage and current data of three power frequency cycles after the fault to form a waveform data array, namely, a voltage waveform data array and a current waveform data array.

[0063] In one example, the protection device collects three-phase voltage and current waveform data on both sides of the distribution line in real time, with a sampling rate of f m The sampling data of three power frequency cycles (60ms) after the fault is saved, and the voltage and current waveform data array with an array length of 6000 is obtained. The voltage and current arrays on the line m side are [U ma , U mb , U mc ] 、[I ma , I mb , I mc ], the voltage and current array on the n side of the line is [U na , Unb , U nc ] 、[I na , I nb , I nc ]. Among them, U ma It is a one-dimensional array with 6000 elements. Any element can be used The same applies to the other voltage and current waveform arrays.

[0064] Optionally, if the power distribution line is an unconventional line such as a two-phase line or a four-phase line, the corresponding voltage waveform data array and current waveform data array can be sampled according to the sampling method of the unconventional line.

[0065] Step S204 , filtering the current waveform data array to obtain a filtered current waveform data array.

[0066] Specifically, the protection device can filter and de-noise the collected current data to obtain a filtered three-phase current waveform data array. The current waveform data array sampled on both sides of m and n is filtered and de-noised to obtain a filtered three-phase current waveform data array on both sides. , . Wherein, a, b, c represent each phase, m represents the m side, and n represents the n side.

[0067] Optionally, if the distribution line is two-phase, four-phase, five-phase, etc., the same method can be used for filtering, and the number of current waveform data arrays obtained is proportional to the number of phases.

[0068] Step S206, determining the voltage qualification rate corresponding to the voltage waveform data array, and determining the waveform similarity corresponding to the filtered current waveform data array when the voltage qualification rate at both ends of the distribution line meets the judgment range.

[0069] The voltage qualification rate is used to indicate the ratio of the voltage of the line that meets the requirements within the sampling time.

[0070] Specifically, the voltage data arrays [U ma , U mb , U mc ]、[U na , U nb ,U nc ]Substitute into the operation and calculate the voltage qualification rate on both sides of the line , . The discrimination range is a preset safety range, within which it is determined that the voltage qualification rates at both ends of the distribution line meet the discrimination range. For example, the discrimination range can be set to [0.8, 1.2]. When the voltage qualification rates on both sides of the distribution line are within the discrimination range at the same time, it is determined that the protection starts immediately; when any one of the voltage qualification rates on both sides of the distribution line is within the discrimination range, it is determined that it starts after the protection delay; when the voltage qualification rates on both sides of the distribution line are not within the discrimination range, it is determined that the protection does not start, and it is determined that there is no fault in the distribution line.

[0071] After the protection is started, the protection device calculates the waveform similarity of the line fault current based on the current waveform data array obtained after filtering. For two-phase, three-phase, four-phase and other distribution lines, the corresponding waveform similarity can be calculated for each phase, that is, the current waveform data corresponding to a phase in the current waveform data array on both sides is used to calculate the corresponding waveform similarity. For example, the waveform similarity of three phases a, b, and c can be obtained for three-phase electricity.

[0072] Step S208, determining a section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold, and determining a protection strategy for the distribution line based on the section discrimination criterion and the overcurrent protection criterion of the distribution line.

[0073] Among them, the discrimination threshold is determined by simulating the waveform similarity of the distribution line under different fault conditions based on the distribution network simulation model. The protection device can use the PSCAD (Power Systems Computer Aided Design) simulation platform to establish a typical distribution network simulation model, set different fault locations, initial phase angles and transition resistances in the model, and simulate to generate rich fault current waveform data. The current waveform data array after filtering at both ends of the line is used to calculate the waveform similarity of the fault line and non-fault line under different fault conditions, and calculate the discrimination threshold of the current waveform similarity. .

[0074] Specifically, the current waveform similarity obtained based on the distribution network simulation model is compared with the line fault discrimination threshold to form a section discrimination criterion. Whether the current waveform similarity is greater than the line fault discrimination threshold can be used as a section discrimination criterion. If the current waveform similarity is greater than the discrimination threshold, it is determined that the distribution line has a fault, otherwise it is determined that the distribution line has not a fault.

[0075] After determining the section discrimination criterion and the overcurrent protection criterion, if the section discrimination criterion and the overcurrent protection criterion are both established, the first protection strategy of the distribution line is determined; if only one of the section discrimination criterion and the overcurrent protection criterion is established, the second protection strategy of the distribution line is determined; if neither the section discrimination criterion nor the overcurrent protection criterion is established, the third protection strategy of the distribution line is determined.

[0076] In the above distribution line protection method, the current waveform data arrays on both sides of the distribution line are obtained, and the current waveform data arrays are filtered to obtain the filtered current waveform data arrays. The voltage waveform data arrays on both sides of the distribution line are obtained to determine the voltage qualification rate corresponding to the voltage waveform data arrays. When it is determined that the voltage qualification rate at both ends of the distribution line meets the discrimination range, the filtered current waveform data arrays are processed to obtain the corresponding waveform similarity. The protection terminal determines the section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold. The section discrimination criterion enables the protection terminal to preliminarily judge whether the distribution line has a fault based on the waveform similarity. The protection terminal also determines the protection strategy for the distribution line based on the section discrimination criterion and the overcurrent protection criterion of the distribution line.

[0077] The above method can obtain the voltage and current on both sides of the distribution line, two-dimensional waveform data, and process the waveform data, thereby increasing the data dimension used to determine the protection strategy and improving the accuracy of determining the protection strategy. Afterwards, it is necessary to determine whether to protect the distribution line when the voltage qualification rate and waveform similarity corresponding to the voltage and current meet the judgment range and judgment criteria respectively. It can accurately identify and determine the prerequisites for executing the protection strategy, and comprehensively determine the specific protection strategy based on the section judgment criteria and overcurrent protection criteria to improve the safety of the distribution line.

[0078] In an exemplary embodiment, the specific implementation process of the step of "filtering the current waveform data array to obtain a filtered current waveform data array" includes:

[0079] Based on the cutoff frequency and the filter order, the first elements corresponding to the multi-phase electricity in the current waveform data array on both sides of the distribution line are calculated to obtain the filter values ​​corresponding to each first element; the corresponding filter values ​​in the multi-phase electricity are merged to obtain the filtered current waveform data array on both sides of the distribution line.

[0080] The cutoff frequency is used to indicate the lowest frequency allowed to pass through the signal; the first element is the single current waveform data without filtering. If the distribution line is multi-phase, each phase has a corresponding first element. In one example, if the distribution line is three-phase, the three-phase current waveform data array can be , . Indicates the current waveform data corresponding to a on the m side, Contains multiple corresponding first elements.

[0081] Specifically, the protection device multiplies the first elements corresponding to multiple phases in the current waveform data array based on the product value between the cutoff frequency and the inverse of the filter order to obtain the filter value corresponding to each first element, and combines the multiple filter values ​​to obtain the current waveform data array after filtering each phase. The current waveform data array obtained after filtering is .

[0082] In one example, the protection device filters and de-noises the sampled current waveform data on the m and n sides, and obtains the filtered three-phase current waveform data arrays on both sides. , , taking the m side as an example, the filtering process is:

[0083]

[0084] In the above formula: N is the filter order, which can be 100; f c The cut-off frequency is used to indicate the lowest frequency allowed to pass through the signal, and the value can be 10kHz; , , They respectively represent the elements in the array of the three-phase current waveform data of a, b, and c collected on the line m side; , , is the array of three-phase current data on the m side of the line after filtering; the current data on the n side of the line is processed in the same way.

[0085] In this embodiment, a filtered current waveform data array corresponding to multi-phase electricity can be obtained by filtering, impurities in the current waveform data can be eliminated, and the accuracy of the acquired current waveform data can be improved.

[0086] In an exemplary embodiment, the specific implementation process of the step of "determining the voltage qualification rate corresponding to the voltage waveform data array" includes:

[0087] For the voltage waveform data arrays on both sides of the distribution line, determine the sum of the squares of the second elements corresponding to the multi-phase electricity in the voltage waveform data array; multiply the number of second elements by the square of the preset voltage value of the distribution line to obtain the product value; determine the quotient of the sum of squares and the product value as the voltage qualification rate corresponding to the voltage waveform data array.

[0088] The second element is each element in the voltage waveform data array.

[0089] Specifically, the protection device extracts the second elements in the voltage waveform data array collected on both sides of the line, and for each second element, calculates the square of each phase electricity, and sums the square of each phase electricity to obtain the sum of squares corresponding to multiple second elements. After that, the protection device can multiply the number of second elements by the square of the preset voltage value to obtain the product value, and finally divide the sum of squares corresponding to the multiple second elements by the product value to obtain the voltage qualification rate corresponding to the voltage waveform data array.

[0090] In one example, when the distribution line is three-phase electricity, the voltage data array [U ma , U mb , U mc ]、[U na , U nb , U nc ]Substitute into the operation and calculate the voltage qualification rate on both sides of the line , , and its calculation formula is as follows:

[0091]

[0092]

[0093] In the formula, It is 10% of the rated voltage of the distribution line. For a 10kV medium voltage distribution network, it can be taken as 1kV. , , They respectively represent the elements in the three-phase voltage waveform data array at the line m side; , , They respectively represent the elements in the three-phase voltage waveform data array on the n side of the line.

[0094] In this embodiment, the accuracy of the voltage qualification rate is improved by calculating each second element included in the voltage waveform data array.

[0095] In an exemplary embodiment, the specific implementation process of the step of "determining the waveform similarity corresponding to the filtered current waveform data array when the voltage qualification rate at both ends of the distribution line meets the judgment range" includes:

[0096] If the qualified rate of any voltage at both ends of the distribution line is within the judgment range, for each phase in the multi-phase electricity, determine the first sum of squares of the third elements in the first side waveform array, the second sum of squares of the third elements in the second side waveform array, and the third sum of squares corresponding to the product of the two third elements in the same position of the first side waveform array and the second side waveform array.

[0097] The first square sum, the second square sum and the third square sum are processed in two different primary operations to obtain a first result and a second result; the quotient of the first result and the second result is determined as each corresponding waveform similarity in the filtered current waveform data array.

[0098] The filtered current waveform data array includes a first side waveform array and a second side waveform array; the first side waveform array may correspond to the m side; the second side waveform array may correspond to the n side. The third element is an element in the filtered current waveform data array.

[0099] Specifically, if the qualified rate of any voltage at both ends of the distribution line is within the determination range, the subsequent steps are executed after waiting for a preset time. If the qualified rates of the voltages at both ends of the distribution line are within the determination range, the subsequent steps are executed immediately.

[0100] It should be understood that the waveform similarity of the current needs to calculate the current waveform data arrays on both sides to obtain the waveform similarity of a corresponding one of the multiple phases. Based on this, for each phase in the multi-phase electricity, determine the first square sum of each third element in the waveform array on the first side, the second square sum of each third element in the waveform array on the second side, and the third square sum corresponding to the product of the two third elements in the same position of the waveform array on the first side and the waveform array on the second side. Perform two rounds of preset addition and subtraction operations on the first square sum, the second square sum, and the third square sum to obtain the first result and the second result, and determine the quotient of the first result and the second result as the waveform similarity of the phase.

[0101] In one example, when the multi-phase electricity is three-phase electricity, the protection terminal calculates the waveform similarity of the fault current at both ends of the line using the current waveform data array obtained after filtering, wherein the waveform similarity calculation method of the current of phase a is as follows:

[0102] α a = ∑ k=1 6000 I ma F k 2 + ∑ k=1 6000 [ I na F k 2 +( I ma F k I na F k ) 2 ] ∑ k=1 6000 I ma F k 2 + ∑ k=1 6000 [ I na F k 2 -( I ma F k I na F k ) 2 ]

[0103] In the formula, The similarity coefficient of the current waveform of phase a is calculated in the same way as above. The similarity coefficient of the current waveform of phase b and phase c can be calculated as follows: , , .

[0104] In this embodiment, by calculating the filtered current waveform data array and respectively calculating the waveform similarity of each phase, the accuracy of determining the waveform similarity can be improved.

[0105] In an exemplary embodiment, Figure 3As shown, the method further includes steps S302 to S308. Among them:

[0106] Step S302, determining preset distribution network data and distribution network structure diagram.

[0107] Among them, the distribution network structure diagram includes the connected system power supply, distributed power supply, overhead lines and load equipment; the distribution network data includes the data corresponding to the system power supply, distributed power supply, overhead lines and load equipment.

[0108] Specifically, a typical distribution network simulation model is established using the PSCAD simulation platform. Different fault locations, initial phase angles, and transition resistances are set in the model to generate rich fault current waveform data. The waveform similarity of the fault line and the non-fault line under different fault conditions is calculated using the filtered current waveform data array at both ends of the line, and the current waveform similarity discrimination threshold is calculated. .

[0109] In one example, a typical distribution network simulation model is established using the PSCAD simulation platform, as shown in the attached figure. Figure 5 As shown, where:

[0110] The system power supply is 110kV and the frequency is 50Hz. The distribution network voltage level is 10kV; the line are cables, and the rest are overhead lines. The line length is , , , ; Line resistance , line reactance DG (distributed generation) is as follows Figure 5 The location shown is connected to the distribution network. Considering three types of small wind turbines, small photovoltaic power stations, and small hydropower stations, they are connected with three capacities of 0.1MW, 0.3MW, and 0.5MW respectively. Loads ① and ② are 3MW and 2MW respectively.

[0111] Step S304, simulating the distribution network data and the distribution network structure diagram through the distribution network simulation model, and determining the current waveform data corresponding to both sides of the fault line and both sides of the non-fault line under different fault conditions.

[0112] In one example, different fault conditions are set on a typical distribution network simulation model to obtain voltage and current waveform data on both sides of the line when the line fails. The specific fault setting method is as follows:

[0113] Fault type: single-phase grounding fault, two-phase grounding fault, two-phase interphase fault, three-phase grounding fault, three-phase short circuit fault; fault duration is 1s. Fault initial phase angle: 0~90°, with an interval step of 5°. Transition resistance: 0~300 Ω, with an interval step of 30 Ω. Fault location: 0~100% of the total length of line L2, with an interval step of 10%.

[0114] When various faults occur, the waveforms at both ends of the faulty line and the non-faulty line are sampled at a rate of 1MHz. The three-week data after the fault of the voltage and current waveform data at both ends of each line are intercepted to form a waveform data array [U ma-i , U mb-i ,U mc-i ] 、[I ma-i , I mb-i , I mc-i ]、[U na-i , U nb-i , U nc-i ] 、[I na-i , I nb-i , I nc-i ], where U ma-i Represents the voltage waveform data array of the ith line near the busbar, U na-i Represents the voltage waveform data array of the non-bus side of the i-th line. The other arrays are similar, and the length of each array is 6000. The above fault current sampling data is filtered and denoised in the same way as the above steps to obtain the filtered three-phase current data array , .

[0115] Step S306, based on the current waveform data, determining a first current waveform similarity coefficient array corresponding to the faulty line and a second current waveform similarity coefficient array corresponding to the non-faulty line.

[0116] In one example, the filtered current waveform data array at both ends of the line obtained by simulation in step S304 is used to calculate the current waveform similarity coefficients at both ends of the fault line L2 and the non-fault line (L1, L3, L4) when different distributed power sources are connected and different fault conditions are encountered. , , forming the first current waveform similarity coefficient array of the fault line L2 [ , similarity coefficient array of the second current waveform of the non-fault line .

[0117] Step S308 , determining a discrimination threshold value according to the maximum value in the first current waveform similarity coefficient array and the minimum value in the second current waveform similarity coefficient array.

[0118] In one example, it is determined to take the maximum value in the current waveform similarity coefficient array of the fault line L2 The minimum value in the array of similarity coefficients with the non-fault line current waveform , and the arithmetic average of the accumulated sum of the two is calculated as the current waveform similarity judgment threshold , which is calculated as follows:

[0119]

[0120] In this embodiment, by simulating the distribution line, multiple current waveform data can be determined under various fault conditions, and a discrimination threshold can be determined based on similarity coefficients corresponding to the multiple current waveform data, thereby improving the accuracy of determining the discrimination threshold.

[0121] In an exemplary embodiment, the specific implementation process of the step of "determining the section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold" includes:

[0122] If the waveform similarities of each item in the multi-phase electricity are greater than or equal to the discrimination threshold, it is determined that the distribution line has a fault; if the waveform similarity of any item in the multi-phase electricity is less than the discrimination threshold, it is determined that the distribution line has not a fault.

[0123] In one example, the protection device obtains the similarity of the current waveforms of phases a, b, and c to determine the fault section and form a section discrimination criterion, which is as follows:

[0124]

[0125] If the similarity of the current waveforms of the three phases a, b, and c satisfies the above formula, it is considered that the line has a fault, otherwise, it is judged that the line has not a fault.

[0126] In this embodiment, by determining the threshold and judging the similarity of multiple current waveforms, the accuracy of fault determination can be improved.

[0127] In an exemplary embodiment, the protection strategy includes an instant tripping strategy, a delayed tripping strategy and a blocking protection strategy; the specific implementation process of the step of "determining the protection strategy of the distribution line based on the section discrimination criterion and the overcurrent protection criterion of the distribution line" includes:

[0128] If a fault occurs in the distribution line and any effective value of the current on both sides of the distribution line is greater than a preset threshold, the instant tripping strategy is determined as the protection strategy for the distribution line.

[0129] If a fault occurs in the distribution line and the effective values ​​of the currents on both sides of the distribution line are less than the preset threshold, the delayed tripping strategy is determined as the protection strategy for the distribution line.

[0130] If there is no fault in the distribution line and any effective value of the current on both sides of the distribution line is greater than the preset threshold, the delayed tripping strategy is determined as the protection strategy for the distribution line.

[0131] If there is no fault in the distribution line and the effective values ​​of the currents on both sides of the distribution line are less than the preset threshold, the blocking protection strategy is determined as the protection strategy for the distribution line.

[0132] In one example, the protection strategy includes an instant trip strategy, a delayed trip strategy, and a blocking protection strategy. If the section discrimination criterion and the overcurrent protection criterion are both met, the protection immediately sends a trip signal (instant trip strategy); if only one of the section discrimination criterion and the overcurrent protection criterion is met, the trip signal is sent out with a delay of 200ms (delayed trip strategy); if neither the section discrimination criterion nor the overcurrent protection criterion is met, the protection is blocked (blocking protection strategy).

[0133] In this embodiment, by arranging and combining the section identification criterion and the overcurrent protection criterion, a variety of protection strategies corresponding to the distribution line can be determined, which can improve the safety of the distribution line.

[0134] In an exemplary embodiment, the method further comprises:

[0135] For the filtered voltage waveform data array on both sides of the distribution line, determine the sum of the squares of the third elements corresponding to each phase of the multi-phase electricity in the filtered current waveform data array, which is the fourth square sum; based on the quotient of the fourth square sum and the preset value, determine the effective value of the current on both sides of the distribution line.

[0136] In one example, for three-phase electricity, the effective value of the fault current is calculated using the filtered current waveform data array. The effective value calculation method of the current on the m and n sides is as follows:

[0137]

[0138]

[0139] In the formula, , is the effective value of the current on both sides of the line.

[0140] On this basis, the overcurrent protection criterion is formed as follows:

[0141]

[0142]

[0143] In the above formula, is the overcurrent protection setting value of the line, which can generally be taken as 1.3 , is the line rated current. If at least one of the above two equations is satisfied, the overcurrent protection criterion is established, otherwise, the overcurrent protection criterion is not established.

[0144] In this embodiment, the effective value of the current on both sides of the distribution line is determined by using the third element corresponding to each phase of the multi-phase electricity, so that the accuracy of the effective value of the current can be improved.

[0145] like Figure 4 As shown, the specific execution process of the above distribution line protection method is described in detail below in combination with a specific embodiment, including the following steps:

[0146] Step 1: The protection device collects the voltage and current waveform data at both ends of the distribution line in real time after the fault occurs, saves the voltage and current data of three power frequency cycles after the fault to form a waveform data array, and filters and denoises the collected current data to obtain a filtered three-phase current waveform data array.

[0147] Step 2: Calculate the voltage pass rate using the collected voltage waveform data array , and determine whether the protection is activated.

[0148] Step 3: After the protection is started, the waveform similarity of the line fault current is calculated based on the current waveform data array obtained after filtering .

[0149] Step 4: Use the PSCAD simulation platform to establish a typical distribution network simulation model, set different fault locations, initial phase angles and transition resistances in the model, simulate and generate rich fault current waveform data, use the filtered current waveform data array at both ends of the line to calculate the waveform similarity of the fault line and non-fault line under different fault conditions, and calculate the current waveform similarity judgment threshold ;

[0150] Step 5: Compare the current waveform similarity calculated in step 3 with the line fault judgment threshold to form a section judgment criterion, and combine the criterion with the overcurrent protection criterion to form a comprehensive protection criterion.

[0151] Step 1: The protection device collects the voltage and current waveform data at both ends of the distribution line in real time after the fault occurs, saves the voltage and current data of three power frequency cycles after the fault to form a waveform data array, and filters and denoises the collected current data to obtain a filtered three-phase current waveform data array.

[0152] Furthermore, the specific steps of Step 1 are:

[0153] Step 1: The protection device collects the three-phase voltage and current waveform data on both sides of the distribution line in real time, with a sampling rate of f mThe sampling data of three power frequency cycles (60ms) after the fault is saved, and the voltage and current waveform data array with an array length of 6000 is obtained. The voltage and current arrays on the line m side are [U ma , U mb , U mc ] 、[I ma , I mb , I mc ], the voltage and current array on the n side of the line is [U na , U nb , U nc ] 、[I na , I nb , I nc ]. Among them, U ma It is a one-dimensional array with 6000 elements. Any element can be used The same applies to the other voltage and current waveform arrays.

[0154] Step 2: Filter and denoise the sampled current waveform data on the m and n sides, and obtain the filtered three-phase current waveform data array on both sides , , taking the m side as an example, the filtering process is:

[0155]

[0156] In the above formula: N is the order of the filter, which is 100; f c The cut-off frequency indicates the lowest frequency allowed to pass through the signal, and its value is 10kHz; , , They respectively represent the elements in the array of the three-phase current waveform data of a, b, and c collected on the line m side; , , is the array of three-phase current data on the m side of the line after filtering; the current data on the n side of the line is processed in the same way.

[0157] Step 2: Calculate the voltage pass rate using the collected voltage waveform data array , and determine whether the protection is activated.

[0158] Furthermore, the specific steps of Step 2 are:

[0159] Step 1: Collect the voltage data array [U ma , U mb , U mc ]、[U na , U nb ,U nc]Substitute into the operation and calculate the voltage qualification rate on both sides of the line , , and its calculation formula is as follows:

[0160]

[0161]

[0162] In the formula, It is 10% of the rated voltage of the distribution line. For a 10kV medium voltage distribution network, it can be taken as 1kV. , , They respectively represent the elements in the three-phase voltage waveform data array at the line m side; , , They respectively represent the elements in the three-phase voltage waveform data array on the n side of the line.

[0163] Step 2: Determine whether the protection is activated based on the voltage qualification rate obtained in step 1. The specific criteria are as follows:

[0164]

[0165]

[0166] If the above two formulas are satisfied at the same time, the protection is activated; otherwise, if only one formula is satisfied, the protection is activated with a delay of 160ms; if both formulas are not satisfied, the protection is not activated.

[0167] Step 3: After the protection is started, the waveform similarity of the line fault current is calculated based on the current waveform data array obtained after filtering ;

[0168] Furthermore, the specific steps of Step 3 are:

[0169] Step 1: Calculate the waveform similarity of the fault current at both ends of the line using the current waveform data array obtained after filtering, where the waveform similarity calculation method of the current of phase a is as follows:

[0170] α a = ∑ k=1 6000 I ma F k 2 + ∑ k=1 6000 [ I na F k 2 +( I ma F k I na F k ) 2 ] ∑ k=1 6000 I ma F k 2 + ∑ k=1 6000 [ I na F k 2 - ( I ma F k I na F k ) 2 ]

[0171] In the formula, represents the current waveform similarity coefficient of phase a; the current waveform similarity calculation method of phase b and phase c of the line is the same as above. Thus, the waveform similarity of phases a, b, and c can be calculated , , .

[0172] Step 4: Use the PSCAD simulation platform to establish a typical distribution network simulation model, set different fault locations, initial phase angles and transition resistances in the model, simulate and generate rich fault current waveform data, use the filtered current waveform data array at both ends of the line to calculate the waveform similarity of the fault line and non-fault line under different fault conditions, and calculate the current waveform similarity judgment threshold ;

[0173] Furthermore, the specific steps of Step 4 are:

[0174] Step 1: Use the PSCAD simulation platform to establish a typical distribution network simulation model, as shown in the attached Figure 5 As shown, where:

[0175] 1) The system power supply is 110kV and the frequency is 50Hz.

[0176] 2) The distribution network voltage level is 10kV; the line are cables, and the rest are overhead lines. The line length is , , , ; Line resistance , line reactance .

[0177] 3) DG (distributed generation) is connected to the distribution network at the position shown in the figure. Considering three types of small wind turbines, small photovoltaic power stations, and small hydropower stations, they are connected with three capacities of 0.1MW, 0.3MW, and 0.5MW respectively.

[0178] 4) Loads ① and ② are 3MW and 2MW respectively.

[0179] Step 2: Set different fault conditions on the typical distribution network simulation model to obtain the voltage and current waveform data on both sides of the line when the line fails.

[0180] The specific fault setting method is as follows:

[0181] Fault type: examine single-phase grounding fault, two-phase grounding fault, two-phase phase-to-phase fault, three-phase grounding fault, and three-phase short circuit fault; the fault duration is 1s.

[0182] Fault initial phase angle: 0~90°, setting interval step 5°;

[0183] Transition resistance: 0~300 Ω, with 30 Ω as the interval step;

[0184] Fault location: 0~100% of the total length of line L2, with an interval of 10%.

[0185] When various faults occur, the waveforms at both ends of the faulty line and the non-faulty line are sampled at a rate of 1MHz. The three-week data after the fault of the voltage and current waveform data at both ends of each line are intercepted to form a waveform data array [U ma-i , U mb-i ,U mc-i ] 、[I ma-i , I mb-i , I mc-i ]、[U na-i , U nb-i , U nc-i ] 、[I na-i , I nb-i , I nc-i ], where U ma-i Represents the voltage waveform data array of the ith line near the busbar, U na-i Represents the voltage waveform data array of the non-bus side of the i-th line. The other arrays are similar, and the length of each array is 6000. The above fault current sampling data is filtered and denoised using the method in step 2 of step 1 to obtain the filtered three-phase current data array , .

[0186] Step 3: Using the filtered current waveform data array at both ends of the line obtained by simulation in step 2, use the formula to calculate the current waveform similarity coefficient at both ends of the fault line L2 and the non-fault line (L1, L3, L4) when different distributed power sources are connected and different fault conditions are encountered. , , forming the current waveform similarity coefficient array of the fault line L2 [ , non-fault line current waveform similarity coefficient array .like Figure 6 As shown, it is a schematic diagram of the similarity of fault lines and the similarity of non-fault lines.

[0187] Step 4: Obtain the maximum value in the array of similarity coefficients of the current waveform of the fault line L2 The minimum value in the array of similarity coefficients with the non-fault line current waveform , and the arithmetic average of the accumulated sum of the two is calculated as the current waveform similarity judgment threshold , which is calculated as follows:

[0188]

[0189] In one example, when the distributed generation is connected or not connected, the similarity of the line where F fails is as follows: Figure 7 , Figure 8 As shown; when the distributed generation is connected or not connected, the similarity of the line where F fails is as follows:

[0190] Table 1 Line similarity when F fails without distributed generation

[0191]

[0192] Table 2 Line similarity when F fails under distributed generation access

[0193]

[0194] Step 5: Compare the current waveform similarity calculated in step 3 with the line fault judgment threshold to form a section judgment criterion, and combine the criterion with the overcurrent protection criterion to form a comprehensive protection criterion.

[0195] Furthermore, the specific steps of Step 5 are:

[0196] Step 1: Use the similarity of the current waveforms of phases a, b, and c calculated in step 3 to determine the fault section and form the section determination criterion, as follows:

[0197]

[0198] If the similarity of the current waveforms of the three phases a, b, and c satisfies the above formula, it is considered that the line has a fault, otherwise, it is judged that the line has not a fault.

[0199] Step 2: Calculate the effective value of the fault current using the filtered current waveform data array. The calculation method for the effective value of the current on the m and n sides is as follows:

[0200]

[0201]

[0202] In the formula, , is the effective value of the current on both sides of the line.

[0203] On this basis, the overcurrent protection criterion is formed as follows:

[0204]

[0205]

[0206] In the above formula, is the overcurrent protection setting value of the line, which can generally be taken as 1.3 , is the line rated current. If at least one of the above two equations is satisfied, the overcurrent protection criterion is established, otherwise, the overcurrent protection criterion is not established.

[0207] Step 3: Combine the fault section identification criteria with the overcurrent protection criteria to form a comprehensive protection criterion, as follows:

[0208] If the section discrimination criterion and the overcurrent protection criterion are both met, the protection will immediately send out a tripping signal; if only one of the section discrimination criterion and the overcurrent protection criterion is met, a tripping signal will be sent out after a delay of 200ms; if neither the section discrimination criterion nor the overcurrent protection criterion is met, the protection will be locked.

[0209] In the embodiment of the present application, the voltage starting threshold value is used to calculate the accurate starting of the distribution network line fault identification, avoiding the judgment of the distribution network fault starting due to system interference and other potential factors. The comprehensive protection criterion combining the current waveform similarity with the overcurrent protection criterion can significantly improve the accuracy of identifying the fault line, and solves the problem that the traditional current differential protection and similarity calculation method cannot be applied due to the unmeasurable branches. At the same time, the method of the present invention has low requirements on the computing power of the protection device, takes into account both effectiveness and practicality, and has strong engineering practical value.

[0210] In one embodiment, experimental verification is performed based on two situations in which the distributed power source is connected and the distributed power source is not connected during normal operation.

[0211] Example 1: Before the distributed power supply is connected, the line is loaded and a two-phase short circuit fault is set at point F to examine the similarity coefficient and protection action of each line. In the corresponding step 2, the voltage qualification rate is obtained. , , the protection start condition is met, and the protection is started. In the corresponding step 3, the waveform similarity of phases a, b, and c is calculated. , , In the corresponding step 4, determine the current waveform similarity judgment threshold In the corresponding step 5, the current waveform similarity coefficients of phases a and b both meet the current waveform similarity criterion; the effective current values ​​on both sides of the line are , , Take 1.1kA, in this case, the overcurrent protection criterion is met, and a trip signal is immediately issued.

[0212] Example 2: After the distributed power source is connected, the line is loaded and a two-phase short circuit fault is set at point F to examine the similarity coefficient and protection action of each line. In the corresponding step 2, the voltage qualification rate is obtained according to mathematical statistics. , , the protection start condition is met, and the protection is started. In the corresponding step 3, the waveform similarity of phases a, b, and c is calculated. , , In the corresponding step 4, since this distribution network fast line protection method based on the improved waveform similarity algorithm has good adaptability to distributed power sources, there is no need to Perform the setting, and use the setting data in Example 1 In the corresponding step 5, after calculation, the current waveform similarity coefficients of phases a and b both meet the current waveform similarity criterion; the effective current values ​​on both sides of the line are , , Take 1.1kA, in this case, the overcurrent protection criterion is not met, so the trip signal is issued after a delay of 200ms.

[0213] In summary, this embodiment verifies the correctness and superiority of the present invention. A fast line protection method for distribution network based on improved waveform similarity algorithm realizes fast transmission protection on-site data collection, and uses waveform similarity to distinguish faulty lines, forming a new distribution network protection scheme for fast isolation of faulty lines, and has good applicability in the case of high penetration rate access of distributed new energy.

[0214] It should be understood that, although the steps in the flowcharts involved in the above embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0215] Based on the same inventive concept, the embodiment of the present application also provides a distribution line protection device for implementing the distribution line protection method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more distribution line protection device embodiments provided below can refer to the limitations on the distribution line protection method above, and will not be repeated here.

[0216] In an exemplary embodiment, Fig. 9 As shown, a distribution line protection device 900 is provided, comprising: a data acquisition module 901, a current filtering module 902, a similarity determination module 903 and a strategy determination module 904, wherein:

[0217] The data acquisition module 901 is used to acquire the voltage waveform data array on both sides of the distribution line and the current waveform data array on both sides of the distribution line;

[0218] The current filtering module 902 is used to filter the current waveform data array to obtain a filtered current waveform data array;

[0219] A similarity determination module 903 is used to determine the voltage qualification rate corresponding to the voltage waveform data array, and determine the waveform similarity corresponding to the filtered current waveform data array when the voltage qualification rate at both ends of the distribution line meets the judgment range;

[0220] The strategy determination module 904 is used to determine the section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold, and to determine the protection strategy of the distribution line based on the section discrimination criterion and the overcurrent protection criterion of the distribution line; the discrimination threshold is determined after simulating the waveform similarity of the distribution line under different fault conditions based on the distribution network simulation model.

[0221] Furthermore, the current filtering module 902 is specifically used to: calculate the first elements corresponding to the multi-phase electricity in the current waveform data array on both sides of the distribution line based on the cutoff frequency and the filter order, and obtain the filter values ​​corresponding to each first element; the cutoff frequency is used to represent the lowest frequency allowed to pass in the signal; and merge each corresponding filter value in the multi-phase electricity to obtain the filtered current waveform data array on both sides of the distribution line.

[0222] Furthermore, the similarity determination module 903 is specifically used to: determine the sum of squares of the second elements corresponding to the multi-phase electricity in the voltage waveform data array on both sides of the distribution line; multiply the number of second elements by the square of the preset voltage value of the distribution line to obtain the product value; determine the quotient of the sum of squares and the product value as the voltage qualification rate corresponding to the voltage waveform data array.

[0223] Furthermore, the filtered current waveform data array includes a first side waveform array and a second side waveform array; the similarity determination module 903 is specifically used for: if any voltage qualification rate at both ends of the distribution line is within the judgment range, for each phase in the multi-phase electricity, determining the first square sum of each third element in the first side waveform array, the second square sum of each third element in the second side waveform array, and the third square sum corresponding to the product of two third elements at the same position of the first side waveform array and the second side waveform array; performing two different primary operations on the first square sum, the second square sum and the third square sum to obtain a first result and a second result; determining the quotient of the first result and the second result as each corresponding waveform similarity in the filtered current waveform data array.

[0224] Furthermore, the device also includes a discrimination threshold determination module, which is specifically used to: determine preset distribution network data and distribution network structure diagram, the distribution network structure diagram includes connected system power supplies, distributed power supplies, overhead lines and load equipment; the distribution network data includes data corresponding to the system power supplies, distributed power supplies, overhead lines and load equipment; simulate the distribution network data and the distribution network structure diagram through a distribution network simulation model to determine the current waveform data corresponding to both sides of the fault line and both sides of the non-fault line under different fault conditions; based on the current waveform data, determine a first current waveform similarity coefficient array corresponding to the fault line, and a second current waveform similarity coefficient array corresponding to the non-fault line; determine the discrimination threshold according to the maximum value in the first current waveform similarity coefficient array and the minimum value in the second current waveform similarity coefficient array.

[0225] Furthermore, the strategy determination module 904 is specifically used to: if the waveform similarities of each item in the multi-phase electricity are greater than or equal to the discrimination threshold, determine that a distribution line fault has occurred; if any waveform similarity of each item in the multi-phase electricity is less than the discrimination threshold, determine that the distribution line has not failed.

[0226] Furthermore, the protection strategy includes an instant tripping strategy, a delayed tripping strategy and a locking protection strategy. The strategy determination module 904 is specifically used for: if a distribution line fails and any effective value of the current on both sides of the distribution line is greater than a preset threshold, then the instant tripping strategy is determined as the protection strategy of the distribution line; if a distribution line fails and the effective values ​​of the current on both sides of the distribution line are less than the preset threshold, then the delayed tripping strategy is determined as the protection strategy of the distribution line; if the distribution line does not fail and any effective value of the current on both sides of the distribution line is greater than the preset threshold, then the delayed tripping strategy is determined as the protection strategy of the distribution line; if the distribution line does not fail and the effective values ​​of the current on both sides of the distribution line are less than the preset threshold, then the locking protection strategy is determined as the protection strategy of the distribution line.

[0227] Furthermore, the device also includes an effective value determination module, which is specifically used to: determine, for the filtered voltage waveform data array on both sides of the distribution line, the sum of the squares of the third elements corresponding to each phase of the multi-phase electricity contained in the filtered current waveform data array, which is the fourth square sum; based on the quotient of the fourth square sum and the preset value, determine the effective value of the current on both sides of the distribution line.

[0228] Each module in the above-mentioned distribution line protection device can be implemented in whole or in part by software, hardware or a combination thereof. Each of the above-mentioned modules can be embedded in or independent of a processor in an electronic device in the form of hardware, or can be stored in a memory in an electronic device in the form of software, so that the processor can call and execute operations corresponding to each of the above modules.

[0229] In an exemplary embodiment, an electronic device is provided. The electronic device may be a server, and its internal structure diagram may be as shown in FIG. Fig.10 As shown. The electronic device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the electronic device is used to provide computing and control capabilities. The memory of the electronic device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the electronic device is used to store the current waveform data array and the voltage waveform data array of the distribution line. The input / output interface of the electronic device is used to exchange information between the processor and the external device. The communication interface of the electronic device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a distribution line protection method is implemented.

[0230] Those skilled in the art will understand that Fig.10 The structure shown in the figure is merely a block diagram of a partial structure related to the scheme of the present application, and does not constitute a limitation on the electronic device to which the scheme of the present application is applied. The specific electronic device may include more or fewer components than shown in the figure, or combine certain components, or have a different arrangement of components.

[0231] In an exemplary embodiment, an electronic device is further provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0232] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0233] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0234] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0235] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0236] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A distribution line protection method, characterized in that: The method comprises: Acquire a voltage waveform data array on both sides of a distribution line, and a current waveform data array on both sides of the distribution line; Performing filtering processing on the current waveform data array to obtain a filtered current waveform data array; Determine the voltage qualification rate corresponding to the voltage waveform data array, and determine the waveform similarity corresponding to the filtered current waveform data array when the voltage qualification rates at both ends of the distribution line meet the discrimination range; Based on the waveform similarity and the discrimination threshold, the section discrimination criterion of the distribution line is determined, and based on the section discrimination criterion and the overcurrent protection criterion of the distribution line, the protection strategy of the distribution line is determined; the discrimination threshold is determined after simulating the waveform similarity of the distribution line under different fault conditions based on the distribution network simulation model Wherein, determining the section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold comprises: If the waveform similarities of each item in the multi-phase electricity are greater than or equal to the discrimination threshold, it is determined that the distribution line has a fault; if the waveform similarity of any item in the multi-phase electricity is less than the discrimination threshold, it is determined that the distribution line has not a fault.

2. The method according to claim 1, characterized in that The filtering process is performed on the current waveform data array to obtain a filtered current waveform data array, including: Based on the cutoff frequency and the filter order, the first elements corresponding to the multi-phase electricity in the current waveform data array on both sides of the distribution line are calculated to obtain the filter values ​​corresponding to each of the first elements; the cutoff frequency is used to represent the lowest frequency allowed to pass in the signal; The corresponding filtering values ​​in the multi-phase electricity are combined to obtain an array of filtered current waveform data on both sides of the distribution line.

3. The method according to claim 1, characterized in that The determining of the voltage qualification rate corresponding to the voltage waveform data array comprises: For the voltage waveform data arrays at both sides of the power distribution line, determine the sum of squares of the second elements corresponding to the multi-phase electricity in the voltage waveform data arrays; multiplying the number of the second elements by the square of the preset voltage value of the power distribution line to obtain a product value; The quotient of the square sum and the product value is determined as the voltage qualification rate corresponding to the voltage waveform data array.

4. The method according to claim 1, characterized in that: The filtered current waveform data array includes a first side waveform array and a second side waveform array; when the voltage qualification rate at both ends of the distribution line meets the judgment range, determining the waveform similarity corresponding to the filtered current waveform data array includes: If the qualified rate of any voltage at both ends of the distribution line is within the judgment range, for each phase of the multi-phase electricity, determine the first square sum of each third element in the first-side waveform array, the second square sum of each third element in the second-side waveform array, and the third square sum corresponding to the product of two third elements at the same position of the first-side waveform array and the second-side waveform array; Performing two different primary operation processes on the first square sum, the second square sum, and the third square sum to obtain a first result and a second result; The quotient of the first result and the second result is determined as each corresponding waveform similarity in the filtered current waveform data array.

5. The method according to claim 1, characterized in that The method further comprises: Determine preset distribution network data and distribution network structure diagram, wherein the distribution network structure diagram includes connected system power supply, distributed power supply, overhead line and load equipment; the distribution network data includes data corresponding to the system power supply, the distributed power supply, the overhead line and the load equipment; The distribution network data and the distribution network structure diagram are simulated by the distribution network simulation model to determine the current waveform data corresponding to the two sides of the fault line and the two sides of the non-fault line under different fault conditions; Based on the current waveform data, determining a first current waveform similarity coefficient array corresponding to the fault line and a second current waveform similarity coefficient array corresponding to the non-fault line; A discrimination threshold is determined according to a maximum value in the first current waveform similarity coefficient array and a minimum value in the second current waveform similarity coefficient array.

6. The method according to claim 1, characterized in that The protection strategy includes an instant tripping strategy, a delayed tripping strategy and a blocking protection strategy; the protection strategy of the distribution line is determined based on the section discrimination criterion and the overcurrent protection criterion of the distribution line, including: If a fault occurs in the distribution line and any effective value of a current on both sides of the distribution line is greater than a preset threshold, an instant tripping strategy is determined as a protection strategy for the distribution line; If a fault occurs in the distribution line, and the effective values ​​of the currents on both sides of the distribution line are both less than the preset threshold, determining the delayed tripping strategy as the protection strategy for the distribution line; If the distribution line has not failed, and any effective value of the current on both sides of the distribution line is greater than the preset threshold, then determining the delayed tripping strategy as the protection strategy of the distribution line; If the distribution line has not failed, and the effective values ​​of the currents on both sides of the distribution line are both less than the preset threshold, the blocking protection strategy is determined as the protection strategy for the distribution line.

7. The method according to claim 6, characterized in that The method further comprises: For the filtered voltage waveform data arrays at both sides of the distribution line, determine the sum of squares of the third elements corresponding to each phase of the multi-phase electricity in the filtered current waveform data array as the fourth square sum; Based on the quotient of the fourth square sum and a preset value, the effective value of the current at both sides of the distribution line is determined.

8. A distribution line protection device, characterized in that: The device comprises: A data acquisition module, used to acquire a voltage waveform data array on both sides of a distribution line, and a current waveform data array on both sides of the distribution line; A current filtering module, used for filtering the current waveform data array to obtain a filtered current waveform data array; A similarity determination module, used to determine the voltage qualification rate corresponding to the voltage waveform data array, and determine the waveform similarity corresponding to the filtered current waveform data array when the voltage qualification rate at both ends of the distribution line meets the discrimination range; A strategy determination module is used to determine the section discrimination criterion of the distribution line based on the waveform similarity and the discrimination threshold, and determine the protection strategy of the distribution line based on the section discrimination criterion and the overcurrent protection criterion of the distribution line; the discrimination threshold is determined after simulating the waveform similarity of the distribution line under different fault conditions based on the distribution network simulation model; wherein, the section discrimination criterion of the distribution line is determined based on the waveform similarity and the discrimination threshold, including: if the waveform similarities of each item in the multi-phase electricity are greater than or equal to the discrimination threshold, it is determined that the distribution line has a fault; if the waveform similarity of any item in the multi-phase electricity is less than the discrimination threshold, it is determined that the distribution line has not a fault.

9. The device according to claim 8, characterized in that The current filtering module is specifically used for: Based on the cutoff frequency and the filter order, the first elements corresponding to the multi-phase electricity in the current waveform data array on both sides of the distribution line are calculated to obtain the filter values ​​corresponding to each first element; the cutoff frequency is used to represent the lowest frequency allowed to pass in the signal; the corresponding filter values ​​in the multi-phase electricity are combined to obtain the filtered current waveform data array on both sides of the distribution line.

10. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

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