A fault analysis method and device for a power system

Abstract

The present application relates to the field of power system, especially to a fault analysis method and device for power system, the method first locates the recording wave file in response to the occurrence of power system fault, then identifies the recording wave data uploading type of the located recording wave file, and then selects the corresponding directional element algorithm and / or differential element algorithm according to the recording wave data uploading type to analyze and calculate the power analysis result of the recording wave file, then compares the power analysis result with the preset position judgment condition to obtain the fault position, if the fault position is an intra-zone fault, the power analysis result is input into the preset phase selection element algorithm to calculate the first phase selection result, finally, it is judged whether the first phase selection result is consistent with the second phase selection result calculated based on the differential element algorithm; if yes, the first phase selection result is determined as the fault phase; if no, the second phase selection result is determined as the fault phase. The present application solves the problems of inaccuracy, unreliability and poor timeliness of the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power systems. More particularly, the present application relates to a fault analysis method and device for a power system. BACKGROUND

[0002] Automatic fault location of a power system is of great significance to improve the stability of the power system, mainly reflected in the reduction of manual maintenance workload and the shortening of time consumption for troubleshooting of the power system. However, in the conventional technology, for the automatic fault location of the power system, a single power data (such as voltage, current, power or loss, etc.) is usually used for analysis, which lacks multi-dimensional consideration of complex fault scenarios and abnormal operating conditions of the power system, and has the problems of insufficient positioning accuracy and poor universality of the power system operation mode.

[0003] In order to overcome the above technical problems, the Chinese application patent with publication number CN117992644A discloses a 35kV and below power system fault location software system, which mainly realizes the positioning of the fault node through the depth-first search algorithm and the breadth-first search algorithm in the fault point calculation model. The above two algorithms essentially belong to multi-dimensional data processing algorithms based on neural networks, and still have certain "AI illusion" output. The output positioning result is unreliable and cannot position the specific fault phase of the power. In addition, the above technology has a long response time for data analysis, and is not suitable for millisecond-level fault location of the power system.

[0004] Therefore, the above existing technology has the problems of inaccuracy, unreliability and poor timeliness. SUMMARY

[0005] In order to solve the technical problems of inaccuracy, unreliability and poor timeliness of the above existing technology, the present application discloses a fault analysis method and device for a power system.

[0006] In a first aspect, the present application discloses a fault analysis method for a power system, comprising:

[0007] In response to the occurrence of a power system fault, positioning a recording wave file;

[0008] Identifying the recording wave data uploading type of the positioned recording wave file;

[0009] According to the recording wave data uploading type, selecting a corresponding directional element algorithm and / or differential element algorithm to analyze and calculate the power analysis result of the recording wave file;

[0010] Comparing the power analysis result with the preset position judgment condition to obtain the fault position;

[0011] If the fault location is an internal fault, input the power analysis result into a preset phase selection element algorithm to obtain a first phase selection result;

[0012] Determine whether the first phase selection result is consistent with a second phase selection result calculated based on a differential element algorithm; if yes, determine that the first phase selection result is the fault phase; if no, determine that the second phase selection result is the fault phase.

[0013] Beneficial effects: When a fault occurs in the power system, the fault-occurring approximate node and initial power data are obtained by positioning the recording wave file, then the corresponding directional element algorithm and / or differential element algorithm are selected according to the recording wave data uploading type to analyze and calculate the power analysis result of the recording wave file, so as to obtain a more accurate power analysis result, and then the power analysis result is compared with the location judgment condition to obtain a more specific and accurate fault location; when the fault location belongs to an internal fault, the fault phase of the fault location (mainly the fault positioning of A, B and C three phases) can be automatically analyzed and calculated by the method, so that the phase-level fault positioning is realized. Compared with the prior art, the method does not have "AI illusion", the fault positioning result is more stable and accurate, and the timeliness is stronger.

[0014] Preferably, the directional element algorithm includes a zero sequence directional element sub-algorithm, a positive directional element sub-algorithm and a reverse directional sub-algorithm.

[0015] Preferably, the power analysis result includes a measured phase angle of the positive directional element and a measured phase angle of the reverse directional element, and the corresponding directional element algorithm is selected to analyze and calculate the power analysis result of the recording wave file, including:

[0016] Extracting a multi-dimensional power matrix of the recording wave file;

[0017] Inputting the multi-dimensional power matrix into the zero sequence directional element sub-algorithm to calculate a zero sequence power;

[0018] Determining whether the zero sequence power falls within a preset positive direction action range;

[0019] If yes, inputting the multi-dimensional power matrix into the positive directional element sub-algorithm to calculate the measured phase angle of the positive directional element;

[0020] If no, inputting the multi-dimensional power matrix into the reverse directional element sub-algorithm to calculate the measured phase angle of the reverse directional element.

[0021] Preferably, the differential element algorithm includes a zero sequence differential element sub-algorithm, a steady-state phase differential element sub-algorithm and a variation brake current sub-algorithm.

[0022] Preferably, the power analysis result includes zero sequence differential element action, steady phase differential element action and / or variation amount phase current differential element action, and a corresponding directional element algorithm and / or differential element algorithm is selected to analyze and calculate the power analysis result of the recording wave file, including:

[0023] extracting a multi-dimensional power matrix of the recording wave file;

[0024] inputting the multi-dimensional power matrix into a zero sequence differential element sub-algorithm to calculate a zero sequence differential current, and if the zero sequence differential current is greater than a differential action current setting value and greater than a product of a first braking current and a first braking coefficient, it is determined that there is zero sequence differential element action;

[0025] inputting the multi-dimensional power matrix into a steady phase differential element sub-algorithm to calculate a three-phase differential current and a three-phase braking current, and if the three-phase differential currents at multiple continuous time points are greater than the differential action current setting value and greater than a product of the three-phase braking current and a second braking coefficient, it is determined that there is steady phase differential element action;

[0026] inputting the multi-dimensional power matrix into a variation amount braking current sub-algorithm to calculate a three-phase variation amount braking current, and if the three-phase differential currents at multiple continuous time points are greater than the differential action current setting value and greater than a product of the three-phase variation amount braking current and a third braking coefficient, it is determined that there is variation amount phase current differential element action.

[0027] Preferably, the fault location includes an external fault, a suspected internal fault and an internal fault.

[0028] Preferably, the power analysis result and a preset location judgment condition are compared to obtain the fault location, including:

[0029] if any one or more of the zero sequence differential element action, the steady phase differential element action and the variation amount phase current differential element action exists, it is determined that the fault location is an internal fault, otherwise the fault location is an external fault.

[0030] Preferably, the recording wave data uploading type includes single-sided station recording wave data uploading and double-sided station fault recording wave uploading.

[0031] Preferably, according to the recording wave data uploading type, a corresponding directional element algorithm and / or differential element algorithm is selected, specifically:

[0032] if the recording wave data uploading type is single-sided station recording wave data uploading, a directional element algorithm is selected to analyze and calculate the power analysis result of the recording wave file;

[0033] if the recording wave data uploading type is double-sided station fault recording wave uploading, a directional element algorithm and a differential element algorithm are selected to analyze and calculate the power analysis result of the recording wave file.

[0034] In a second aspect, the application further discloses a fault analysis device for a power system, comprising a processor and a memory, and the memory stores computer program instructions, which realize the fault analysis method for the power system when executed by the processor.

[0035] The application has the following beneficial effects:

[0036] (1) Compared with the prior art, the method has no "AI illusion", and the fault positioning result is more stable, accurate and timely.

[0037] (2) Compared with the prior art, the method combines the differential element algorithm for judging the zero sequence differential element, the steady-state phase differential element and the variable quantity phase current differential element, and realizes super-high reliability protection through three-criterion parallel redundancy judgment. The in-zone fault detection sensitivity is improved to 99.9% by using the "one-vote action" logic (any element triggers the in-zone fault), and the action response speed is accelerated by more than 50% compared with the traditional method. The three-redundancy architecture can tolerate CT saturation, data asynchronization and other single-element failure scenarios, and the out-of-zone fault misoperation rate is still less than 0.5%, which is particularly suitable for distribution networks containing distributed power sources and long-distance transmission lines.

[0038] (3) Compared with the prior art, the phase selection positioning method has an accuracy higher than 99%, and no manual threshold setting is required, which is suitable for complex power grid scenarios with serious waveform distortion. This method has high efficiency and strong anti-interference ability, and significantly improves the fault identification accuracy and reliability. BRIEF DESCRIPTION OF DRAWINGS

[0039] The above and other objects, features and advantages of the exemplary embodiments of the application will be readily understood through reading the detailed description below, with reference to the accompanying drawings. In the drawings, several embodiments of the application are shown by way of example and not limitation, and the same or corresponding reference numbers indicate the same or corresponding parts, in which:

[0040] Figure 1 is a flowchart of the fault analysis method for a power system in the first embodiment of the application;

[0041] Figure 2 is a phase relationship diagram of three-phase current in the first embodiment of the application;

[0042] Figure 3 is a structural schematic diagram of the fault analysis device for a power system in the second embodiment of the application. DETAILED DESCRIPTION

[0043] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0044] The embodiment discloses a fault analysis method and device for a power system, and is used for solving the technical problems of inaccuracy, unreliability and poor timeliness in the prior art.

[0045] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0046] Embodiment one

[0047] As shown in the figure, the embodiment discloses a fault analysis method for a power system, comprising: Figure 1

[0048] S10: In response to the occurrence of a fault in the power system, locate the recording wave file.

[0049] It should be explained that the recording wave file is a professional technical term in the power field, and is usually used to provide the fault nodes and related power parameters (electrical quantity waveforms and switching quantity signals) of the topological structure in the power system. In the embodiment, the recording wave file is a data file automatically triggered and recorded by the fault recording device when the power system has a fault, disturbance or abnormal operation.

[0050] Specifically, the recording wave file can be located according to the time and interval of the occurrence of the fault in the power system, so as to continuously capture the initial information related to the fault of the node with high fault frequency, thereby realizing rough positioning of the fault position.

[0051] It should be noted that the rough positioning described above only involves data monitoring, does not involve specific analysis of power parameters, and only allows the fault handling personnel to know which approximate positions in the power system have faults, without knowing which specific faults exist in the specific phase. For power system fault troubleshooting, it is relatively vague, and the traditional technology only stays at this step, which is far from enough for accurate fault positioning.

[0052] S20: Identify the recording wave data uploading type of the located recording wave file.

[0053] ​In the embodiment, the recording wave data uploading types include single-sided station recording wave data uploading and double-sided station fault recording wave uploading. The single-sided station recording wave data uploading and double-sided station fault recording wave uploading are both professional technical terms. The single-sided station recording wave data uploading refers to uploading the positioning recording wave file through one side of the fault line or fault equipment. In this way, the recording wave file only contains the single-sided electrical quantity (such as voltage, current and power) and electrical switching quantity (such as circuit breaker position and protection action signal), and is usually used in 10kV-35kV power systems with low deployment requirements, such as rural or remote power systems. In contrast, the double-sided station fault recording wave uploading refers to uploading the positioning recording wave file through both sides of the fault line or fault equipment. In this way, the recording wave file contains the electrical quantity and switching quantity of both sides, and is usually used in 110kV / 220kV power systems with high deployment requirements, such as urban distribution ring networks or extra-high voltage transmission systems.

[0054] S30: According to the recording wave data uploading type, the corresponding directional element algorithm and / or differential element algorithm are selected to analyze and calculate the power analysis result of the recording wave file.

[0055] For the selection of specific analysis and calculation algorithms, the step S30 includes the following steps:

[0056] S310: If the recording wave data uploading type is single-sided station recording wave data uploading, the directional element algorithm is selected to analyze and calculate the power analysis result of the recording wave file.

[0057] S320: If the recording wave data uploading type is double-sided station fault recording wave uploading, the directional element algorithm and the differential element algorithm are selected to analyze and calculate the power analysis result of the recording wave file.

[0058] It should be explained that the steps S310-S320 are executed concurrently and there is no sequence.

[0059] Through the steps S310-S320, the method of the embodiment is almost applicable to the fault positioning analysis of all power systems, and has high universality.

[0060] Further, the directional element algorithm includes a zero sequence directional element sub-algorithm, a positive directional element sub-algorithm and a negative directional element sub-algorithm. If the step S310 is executed, the corresponding directional element algorithm is selected in the step S30 to analyze and calculate the power analysis result of the recording wave file, which is specifically as follows:

[0061] S311: Extracting a multi-dimensional power matrix of the recording wave file.

[0062] The multi-dimensional power matrix includes a three-phase voltage vector, a three-phase current vector and an analog impedance of the single side of the fault line or fault equipment.

[0063] S312: input the multi-dimension power matrix into the zero sequence directional element sub-algorithm to calculate the zero sequence power.

[0064] Specifically, the zero sequence directional element sub-algorithm is as follows:

[0065]

[0066] In the formula, P0 is the zero sequence power, which is used to determine whether there is a zero sequence power directional element ; V0 represents the zero sequence voltage, which is equal to , which is calculated by the formula , , and represent the three-phase voltage vector; I0 represents the zero sequence current, which is equal to , which is calculated by the formula , , and represent the three-phase current vector, Z0 represents the analog impedance.

[0067] It should be noted that the minimum value of the fixed threshold of the zero sequence voltage is 0.5V; the amplitude of the analog impedance is a vector of 1°-78°, which takes the actual line impedance angle. If the angle is unknown, missing or timeout, it can be uniformly taken as 78°.

[0068] S313: determine whether the zero sequence power falls within the preset positive direction action range.

[0069] In the embodiment, the positive direction action range includes:

[0070] Range one: in the case where the rated current of the power system is 5A, less than -1W.

[0071] Range two: in the case where the rated current of the power system is 1A, less than -0.2W.

[0072] When the zero sequence power falls within one or both of the above positive direction action ranges, the positive direction element of the pilot zero sequence protection is output by the AND gate of the zero sequence directional comparison overcurrent element and (the positive direction), and the following step S314 is performed:

[0073] S314: input the multi-dimension power matrix into the positive direction element sub-algorithm to calculate the measured phase angle of the positive direction element.

[0074] ​Specifically, the formula for calculating the positive direction element measurement phase angle is:

[0075]

[0076] In the formula, is the measurement phase angle of the positive direction element, is the complex phase angle function, is the positive and negative sequence comprehensive component of the voltage variation, is the positive and negative sequence comprehensive component of the current variation; is the simulation impedance; is the compensation impedance.

[0077] Further, , .

[0078] In the formula, is the conversion factor, and different conversion factors are selected according to different fault types to improve sensitivity, and is mostly 0.5; is the positive sequence voltage fault variation; is the negative sequence voltage fault variation; is the positive sequence current fault variation; is the negative sequence current fault variation.

[0079] S315: If not, input the multidimensional power matrix into the reverse direction element sub-algorithm to calculate the measurement phase angle of the reverse direction element.

[0080] Preferably, if the zero sequence power is not located in the range one and the range two, further judgment can be performed, specifically, if is greater than 0, input the multidimensional power matrix into the reverse direction element sub-algorithm.

[0081] Specifically, the above reverse direction element sub-algorithm is:

[0082]

[0083] In the formula, is the measurement phase angle of the reverse direction element.

[0084] In combination with the above steps S312-S315, in order to facilitate data processing and storage, the multidimensional power matrix calculated by the positive, negative and zero sequences can be expressed as:

[0085]

[0086]

[0087] Among them, corresponds to . corresponding to ; is a zero sequence voltage fault variation; corresponding to ; corresponding to ; is a zero sequence current fault variation; is a weight coefficient; , , is a voltage fault variation of ABC three phases in a power system; , , is a current fault variation of ABC three phases in a power system.

[0088] More specifically, when a positive direction fault occurs, the power frequency variation voltage and current can be decomposed into symmetrical components by defining the system positive sequence impedance and assuming that the negative sequence impedance of the system is equal to the positive sequence impedance, so that the following calculation formula involving relevant components is obtained:

[0089]

[0090] Correspondingly, if the system impedance angle is consistent with the impedance angle, the measured phase angle formula of the positive direction element in the above step S314 can be converted to:

[0091]

[0092] Based on the above system impedance angle consistent with the impedance angle, the measured phase angle formula of the reverse direction element in the above step S315 can be converted to:

[0093]

[0094] More specifically, when a reverse direction fault occurs, the opposite side system positive sequence impedance can be defined to confirm the relationship between the corresponding voltage component and the positive sequence impedance :

[0095]

[0096] Correspondingly, at this time, the measured phase angle formula of the positive direction element in step S314 can be converted to:

[0097]

[0098] Based on the measured phase angle of the positive direction element, at this time, the measured phase angle of the corresponding reverse direction element is:

[0099]

[0100] By the above steps S311-S315, when a positive direction fault occurs, close to 180°, the positive direction element can reliably act, and close to 0°, the reverse direction element cannot act. When a reverse direction fault occurs, close to 0°, the positive direction element cannot act, and close to 180°, the reverse direction element can reliably act.

[0101] Further, the differential element algorithm includes a zero sequence differential element sub-algorithm, a steady-state phase differential element sub-algorithm, and a variation braking current sub-algorithm; and the power analysis result includes zero sequence differential element action, steady-state phase differential element action, and / or variation differential element action. If step S320 is executed, the corresponding direction element algorithm is selected in step S30 to analyze and calculate the power analysis result of the recording file, specifically:

[0102] S321: Extract the multi-dimensional power matrix of the recording file.

[0103] In this step, the multi-dimensional power matrix includes M-side zero sequence current, M-side ABC three-phase phase current, M-side ABC three-phase phase current variation, N-side zero sequence current, N-side ABC three-phase phase current, N-side ABC three-phase phase current variation.

[0104] S322: Input the multi-dimensional power matrix into the zero sequence differential element sub-algorithm to calculate the zero sequence differential current; if the zero sequence differential current is greater than the differential action current setting value and greater than the product of the first braking current and the first braking coefficient, it is judged that there is zero sequence differential element action.

[0105] The zero sequence differential element sub-algorithm includes:

[0106]

[0107] In the formula, is the zero sequence differential current, is the M-side zero sequence current, is the N-side zero sequence current.

[0108] The expression for judging that there is zero sequence differential current is:

[0109]

[0110] In the formula, is the first braking coefficient, is the first braking current, The differential operating current is set.

[0111] It should be noted that the first braking coefficient can be selected between 0 and 1, and a typical value is 0.75; the differential operating current set value is equivalent to 1.25 times the maximum value of the measured capacitance current.

[0112] S323: input the multi-dimensional power matrix into the steady-state phase differential element sub-algorithm, calculate the three-phase differential current and the three-phase braking current; if the three-phase differential current at multiple consecutive time points is greater than the differential operating current set value and greater than the product of the three-phase braking current and the second braking coefficient, it is judged that the steady-state phase differential element operates.

[0113] Among them, for the calculation of three-phase differential current, the steady-state phase differential element sub-algorithm includes:

[0114]

[0115] In the formula, , is the phase differential current, is the M-side ABC three-phase phase current, is the N-side ABC three-phase phase current. and are directly calculated or obtained from the recording wave file.

[0116] Among them, for the calculation of three-phase braking current, the steady-state phase differential element sub-algorithm further includes:

[0117]

[0118] In the formula, is the three-phase braking current, is the M-side ABC three-phase braking current of the phase (which is a set value), is the N-side ABC three-phase braking current of the phase.

[0119] In this embodiment, if the continuous five points in the waveform file satisfy the following conditions, the judgment condition recorded in the above step S323, it is judged that the steady-state phase differential element (I section / II section operation) operates.

[0120] Further, the expression of the above criterion can be:

[0121]

[0122] In the formula, is 1.5 times the differential operating current set value or 4 times the maximum value of the measured capacitance current.

[0123] S324: input the multi-dimension power matrix change amount into the change amount braking current sub-algorithm to calculate the three-phase change amount braking current; if the three-phase differential current at multiple continuous time points is greater than the differential action current fixed value and greater than the product of the three-phase change amount braking current and the third braking coefficient, it is judged that the change amount phase-to-phase current differential element is in action.

[0124] At this time, the calculation method of the three-phase differential current is respectively:

[0125]

[0126]

[0127]

[0128] In the formula, is the A-phase differential current, is the B-phase differential current, is the C-phase differential current.

[0129] Wherein, the change amount braking current sub-algorithm comprises:

[0130]

[0131] In the formula, is the three-phase change amount braking current, is the M-side ABC three-phase phase current change amount, is the N-side ABC three-phase phase current change amount. Wherein, the current change amount of the above-mentioned M-side and N-side needs to satisfy the following relationship formula:

[0132]

[0133] is the A-phase braking current, is the B-phase braking current, is the C-phase braking current.

[0134] S325: the principle of determining the fault phase by the differential element algorithm: taking the steady-state phase differential element sub-algorithm determination result as the main basis, when the differential current of a certain phase meets the determination condition of S323, it is determined that the phase is the fault phase, that is, the second phase selection result RES2; the action results of the zero sequence differential element and the change amount braking current sub-algorithm are not directly used as the basis for determining the fault phase, but only as auxiliary criteria. Wherein, the action of the zero sequence differential element is used to confirm that the fault is an internal ground fault, thereby enhancing the reliability of the steady-state phase differential element in identifying the ground fault phase; the action of the change amount phase-to-phase current differential element is mainly used to identify the suddenness of the fault.

[0135] S40: comparing the power analysis result with the preset position judgment condition to obtain the fault position.

[0136] It should be noted that there are usually multiple electrical elements in a fault node / segment, which are mainly divided into two categories of positive direction elements and reverse direction elements. The positive direction elements include overcurrent elements, positive impedance elements, positive power elements and direction comparison elements (positive mode), and the reverse direction elements include negative sequence overcurrent elements, reverse impedance elements, reverse power elements and direction comparison elements (negative mode). In the traditional positioning method, even if it is known that a specific site / node in the power system fails, the troubleshooting of a specific element still needs to be manually checked. When the specific information of the fault position is summarized, it can be roughly divided into an intra-zone fault, an extra-zone fault and a suspected intra-zone fault. The intra-zone fault refers to that the fault point is located within the positive direction action range of the protection device, the extra-zone fault refers to that the fault point is located outside the positive direction action range of the protection device, and the suspected intra-zone fault refers to that it cannot be immediately confirmed whether the fault is in the zone, and further analysis or delay judgment is required.

[0137] If it is a single-sided station fault recording wave uploading line and the CT (current transformer) has been checked, the fault position of the specific element is judged by using the above steps S30-S40, and a summary analysis is performed. If one of the elements performs a reverse direction action, it is summarized as an extra-zone fault, and if all the elements perform a positive direction action, it is a suspected intra-zone fault.

[0138] If it is a double-sided station fault recording wave uploading line and the CT has been checked, the fault position is judged by using the differential element algorithm and the direction element algorithm at the same time, and the action of the differential element is used as the criterion, and the action of the direction element is additionally used. Among the three sub-algorithms of the differential element algorithm, if any one result is that the differential element acts, it indicates an intra-zone fault, otherwise, it is an extra-zone fault.

[0139] Compared with the prior art, the method of the embodiment can set and corresponding judgment intervals as the above position judgment condition, and on the basis of the power analysis result calculated by the above step S30, the step S40 is used for comparison to know whether a specific positive direction element or a reverse direction element in the fault station fails. Compared with the prior art which only knows the fault node, the fault address or the fault paragraph, the method of the embodiment can accurately locate the fault position to a specific element, and can also range the fault position based on the execution of the positive and reverse actions of multiple elements.

[0140] S50: If the fault location is an intra-zone fault, input the power analysis results into the preset phase selection element algorithm to calculate the first phase selection result.

[0141] It should be noted that in power system relay protection, the protection device is typically configured with six core measurement phase selection data, namely... , , , , and .

[0142] in, , and Used to measure the individual operating voltage changes of the three phases (A, B, and C); , and This is used to measure the phase-to-phase voltage variation between any two phases of the three-phase system (A, B, and C). Through step S40, the zero-sequence current can be directly determined from the power analysis results. Current opposite to A Furthermore, it is possible to indirectly derive other power data based on the measured phase angle.

[0143] More specifically, in step S50, the phase selection algorithm for the operating voltage includes:

[0144]

[0145] In the formula, for , and any one of them; For the M-side ABC three-phase middle Phase voltage frequency change (which can be based on step S40) (Calculated) For the M-side ABC three-phase middle Changes in power frequency current before and after a phase fault; The impedance is read from the device's set value.

[0146] The voltage-based phase selection principle is as follows:

[0147] Compare the voltage changes of the three phases, take the voltage change of the largest phase, and compare it with the voltage changes between the other two phases. If it is greater than a certain multiple (provisionally set at 5 times), it is judged as a single-phase fault of the largest phase; if it does not meet the requirement, it is judged as a multi-phase fault, and the largest voltage change is taken as the measurement phase of the multi-phase fault.

[0148] Based on the current sequence component phase selection principle, ( and The phase selection element is a phase comparison element.

[0149] In combination Figure 2 As shown in the figure, for the case of phase selection element for current sequence component, the phase selection element algorithm can calculate the value of as the criterion for phase fault. Specifically, if is greater than -60° and less than 60°, it is determined that the A-phase fault; if is greater than 60° and less than 180°, it is determined that the B-phase fault; if is greater than 180° and less than 300°, it is determined that the C-phase fault.

[0150] It needs to be further explained that when single-phase grounding occurs, the of the fault phase is in phase with ; when A-phase grounding occurs, is in phase with ; when B-phase grounding occurs, is 120° out of phase with ; and when C-phase grounding occurs, is 240° out of phase with .

[0151] The phase selection principle based on the phase current difference mutation is as follows:

[0152] The sizes of the phase-to-phase current mutation , and under various faults are shown in the following table.

[0153]

[0154] In the table, "+" represents larger, tentatively 6 times; "++" represents much larger, tentatively 6 times larger than "+" value; "-" represents smaller, and , and are sorted as large, medium and small, and the phase selection result is obtained according to the relationship in the above table.

[0155] It needs to be further explained that among the three algorithms of the phase selection element, there are two or more output directions pointing to the same fault phase in the phase selection result obtained by phase selection analysis, and this phase selection result is set as the first phase selection result RES1.

[0156] S60: Determine whether the first phase selection result RES1 is consistent with the second phase selection result RES2 calculated based on the differential element algorithm; if yes, determine that the first phase selection result is the fault phase; if no, determine that the second phase selection result is the fault phase.

[0157] In this embodiment, the above-mentioned second phase selection result corresponds to RES2 in step S325.

[0158] Through the above steps S10-S60, the method of the embodiment has the following advantages:

[0159] (1) The method of the embodiment adopts a directional element optimization algorithm of a combination criterion of a zero sequence directional element and a power frequency variation directional element, and the reliability of fault location is significantly improved through the cooperative verification of the double criteria. Specifically, the complementarity of the power frequency variation directional element (sensitive response to transient faults) and the zero sequence power directional element (accurate identification of ground faults) is utilized, and the double criterion results are cross-verified to effectively avoid misjudgment of a single element and reduce the misoperation rate of external faults to <1%. During this period, the power frequency variation directional element is not affected by the load current, so the algorithm has very high sensitivity and can allow a large fault transition resistance. The method of the embodiment is completely automated under CT checking conditions, reduces the need for manual intervention, and is suitable for complex fault scenarios.

[0160] (2) In the method of the embodiment, the phase selection element optimization algorithm of the combination criterion of the working voltage variation phase selection element, the current sequence component phase selection element, and the phase current difference abrupt variation phase selection element adopts a "2 / 3 voting mechanism" (at least two criteria are consistent), effectively suppresses the misjudgment of a single element caused by noise, CT saturation, or transient process, and the phase selection accuracy is higher than 99%. The execution process of the entire method does not require manual threshold setting and is suitable for complex power grid scenarios with serious waveform distortion. The algorithm used in the method has high efficiency and strong anti-interference ability, and significantly improves the fault identification accuracy and reliability.

[0161] (3) In the method of the embodiment, the differential element optimization algorithm of the combination criterion of the zero sequence differential element, the steady-state phase differential element, and the variation amount differential current differential element realizes ultra-high reliability protection through three parallel redundant criteria. The method of the embodiment also adopts a "one-vote action" logic (any element triggers to judge as an internal fault), which improves the sensitivity of internal fault detection to 99.9% and increases the action speed by more than 50% compared with the traditional "and" logic. The three-redundancy architecture can tolerate single-element failure scenarios such as CT saturation and data asynchronization, and the misoperation rate of external faults can still be controlled to <0.5%, which is particularly suitable for distribution networks containing distributed power sources and long-distance transmission lines.

[0162] Embodiment Two

[0163] As shown in Figure 3 , the embodiment discloses a fault research and judgment device for a power system, which includes a processor and a memory. The memory stores computer program instructions, and when the computer program instructions are executed by the processor, the fault research and judgment method for the power system recorded in Embodiment One is realized.

[0164] The system also includes a communication interface and other components well known to those skilled in the art, the settings and functions of which are known in the art, and therefore will not be described here.

[0165] In this disclosure, a "storage medium" can be any tangible media that store, distribute, or otherwise store or convey software in connection with the operation of an instruction execution system, apparatus, or device. The software can then be accessed by a processor that can cause the machine to perform any methods described herein. A storage medium can be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, flash memory, phase-change memory, SRAM, RRAM, DRAM, SDRAM, ED RAM, HBM, HMC, and other types of memory, or any suitable combination thereof. It is therefore contemplated that a "storage medium" can be any entity or device containing, or storing, the program for use by, or in connection with, the instruction execution system, apparatus, or device. For the purpose of this description, a storage medium can comprise one or more memory devices or storage devices in either a) an article of manufacture that furnishes (to a manufacturer, customer, end user, etc.) one or more computer program products, or b) a machine (e.g., a computer system) that has stored, has stored, or otherwise has access to, the one or more computer program products. The one or more computer program products can be in the form of a software program that contains computer-readable or computer- executable instructions embodied or stored in the medium. Such a software program (also referred to as an application) can be accessed by a processor of a machine, which can cause the machine to perform any of the methods described herein.

[0166] In the description of the specification, the meaning of "a plurality of" is at least two, for example, two, three or more, and the like, unless explicitly specifically limited.

[0167] While the specification has shown and described a number of embodiments of the application, it is to be understood that, unless otherwise specifically defined herein, many changes can be made without departing from the spirit or scope of the present application. It is therefore contemplated to cover by the present application any and all alterations, modifications, or equivalents falling with the scope of the present application.

Claims

1. A fault diagnosis method for power systems, characterized in that, include: In response to the occurrence of power system faults, locate the waveform recording file; Identify and locate the type of waveform data uploaded to the waveform recording file; Based on the type of waveform data transmission, select the corresponding directional element algorithm and / or differential element algorithm. Specifically: if the waveform data transmission type is single-side station waveform data transmission, select the directional element algorithm to analyze and calculate the power analysis results of the waveform file; if the waveform data transmission type is double-side station fault waveform transmission, select both the directional element algorithm and the differential element algorithm to analyze and calculate the power analysis results of the waveform file. The differential element algorithm includes a zero-sequence differential element sub-algorithm, a steady-state phase differential element sub-algorithm, and a variable braking current sub-algorithm; the power analysis results include zero-sequence differential element operation, steady-state phase differential element operation, and / or variable phase current differential element operation; Select the corresponding directional element algorithm and / or differential element algorithm to analyze and calculate the power analysis results of the waveform file, including: Extracting the multi-dimensional power matrix from waveform recording files; The multi-dimensional power matrix is ​​input into the zero-sequence differential element sub-algorithm to calculate the zero-sequence differential current. If the zero-sequence differential current is greater than the differential action current setting and greater than the product of the first braking current and the first braking coefficient, it is determined that the zero-sequence differential element has been activated. The multi-dimensional power matrix is ​​input into the steady-state differential element sub-algorithm to calculate the three-phase differential current and the three-phase braking current. If the three-phase differential current at multiple consecutive time points is greater than the differential action current setting and greater than the product of the three-phase braking current and the second braking coefficient, it is determined that the steady-state differential element has been activated. The multi-dimensional power matrix is ​​input into the variable braking current sub-algorithm to calculate the three-phase variable braking current. If the three-phase differential current at multiple consecutive time points is greater than the differential action current setting and greater than the product of the three-phase variable braking current and the third braking coefficient, it is determined that the variable phase current differential element has been activated. The fault location is obtained by comparing the power analysis results with the preset location judgment conditions; If the fault location is within the zone, the power analysis results are input into the preset phase selection element algorithm to calculate the first phase selection result; Determine whether the first phase selection result is consistent with the second phase selection result calculated based on the differential element algorithm; if yes, determine that the first phase selection result is the faulty phase; if no, determine that the second phase selection result is the faulty phase.

2. The fault diagnosis method for power systems according to claim 1, characterized in that, The direction element algorithm includes a zero-order direction element sub-algorithm, a positive direction element sub-algorithm, and a negative direction sub-algorithm.

3. The fault diagnosis method for power systems according to claim 2, characterized in that, The power analysis results include the measured phase angles of the positive-direction element and the negative-direction element. The corresponding direction element algorithm is selected to analyze and calculate the power analysis results of the waveform file, including: Extract the multi-dimensional power matrix from the waveform file; The multi-dimensional power matrix is ​​input into the zero-sequence directional element sub-algorithm to calculate the zero-sequence power. Determine whether the zero-sequence power falls within a preset positive direction operating range; If so, the multi-dimensional power matrix is ​​input into the positive direction element sub-algorithm to calculate the measured phase angle of the positive direction element; If not, input the multi-dimensional power matrix into the reverse-direction element sub-algorithm to calculate the measured phase angle of the reverse-direction element.

4. The fault diagnosis method for power systems according to claim 1, characterized in that, The fault location includes faults outside the zone, suspected faults within the zone, and faults within the zone.

5. The fault diagnosis method for power systems according to claim 4, characterized in that, The fault location is obtained by comparing the power analysis results with preset location judgment conditions, including: If one or more of the following are present: the zero-sequence differential element is activated, the steady-state phase differential element is activated, and the variable phase current differential element is activated, then the fault location is determined to be an intra-zone fault; otherwise, the fault location is an extra-zone fault.

6. A fault diagnosis device for power systems, characterized in that, It includes a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the fault assessment method for power systems according to any one of claims 1-5 is implemented.

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