Fault diagnosis method and device for voltage limiter of series compensation device

Abstract

The invention provides a fault diagnosis method and device for voltage limiters of a series compensation device, and the method comprises the steps: collecting the currents of a plurality of voltage limiter groups of a target series compensation device, the target series compensation device comprises a plurality of voltage limiter branches which are connected in parallel, and each voltage limiter branch comprises at least two voltage limiter groups; determining the current unbalance degree between every two voltage limiter groups according to the current of each voltage limiter group; whether the maximum value of the current unbalance degree between every two voltage limiter sets is larger than a set unbalance degree threshold value or not is diagnosed, and if yes, the voltage limiter set with the large current in the two voltage limiter sets corresponding to the maximum value of the current unbalance degree is determined as the fault voltage limiter set. According to the invention, the efficiency and timeliness of fault diagnosis can be improved on the basis of ensuring the precision of fault diagnosis of the voltage limiter.

Description

Technical Field

[0001] The present application relates to the technical field of voltage limiters, and in particular to a fault diagnosis method and device for a voltage limiter of a series compensation device. Background Art

[0002] Metal-Oxide Varistor (MOV) is the core device for overvoltage protection of series compensation devices. Once a fault occurs, the pressure of the voltage limiter will be released instantly, affecting other primary equipment in the vicinity. In severe cases, it will cause the series compensation device to shut down for a long time.

[0003] In the prior art, MOV fault diagnosis is usually performed by obtaining the MOV imbalance degree based on the MOV branch current and the number of MOV branch poles, and judging whether the MOV imbalance degree exceeds the protection setting value. However, in the early stage of the voltage limiter failure, the change of the MOV branch current may be very small. It is currently difficult to perform MOV fault diagnosis under the condition of small MOV branch current. The main reasons are:

[0004] 1) It is difficult to measure the small current of the MOV branch: The MOV branch current has a large variation range. In order to consider the measurement of normal MOV branch current, the rating of the current transformer is usually the same as the line current rating. When the MOV branch current is small, the measurement accuracy of the current transformer may not be sufficient to reflect the actual MOV branch current, thus affecting the accuracy of the MOV voltage limiter fault.

[0005] 2) High protection setting value: Taking into account the impact of factors such as the initial imbalance of the MOV when it leaves the factory and the low measurement accuracy on the accuracy of the voltage limiter fault diagnosis, the protection setting value is usually set relatively high. However, when the MOV branch current is small, the calculated MOV imbalance is small, which easily leads to low accuracy of MOV fault diagnosis. Summary of the invention

[0006] In view of at least one problem in the prior art, the present application proposes a fault diagnosis method and device for a voltage limiter of a series compensation device, which can improve the efficiency and timeliness of fault diagnosis while ensuring the accuracy of voltage limiter fault diagnosis.

[0007] In order to solve the above technical problems, this application provides the following technical solutions:

[0008] In a first aspect, the present application provides a fault diagnosis method for a voltage limiter of a series compensation device, comprising:

[0009] Collecting currents of multiple voltage limiter groups of a target series compensation device, wherein the target series compensation device comprises: multiple voltage limiter branches connected in parallel, each voltage limiter branch comprises: at least two of the voltage limiter groups;

[0010] Determining the current imbalance between two voltage limiter groups according to the current of each voltage limiter group;

[0011] It is diagnosed whether the maximum value of the current imbalance between the two voltage limiter groups is greater than a first imbalance threshold value. If so, the group with a larger current among the two voltage limiter groups corresponding to the maximum value of the current imbalance is determined as a faulty voltage limiter group.

[0012] In one embodiment, the fault diagnosis method of the series compensation device voltage limiter further includes:

[0013] Obtaining the historical current of each group of the voltage limiter groups collected last time;

[0014] Determining the historical current imbalance between any two voltage limiter groups according to the historical current of each voltage limiter group;

[0015] Correspondingly, after determining the current imbalance between the two voltage limiter groups according to the current of each group of the voltage limiter groups, the method further includes:

[0016] Determine the change amount of the current unbalance between the two voltage limiter groups according to the current unbalance between the two voltage limiter groups and the historical current unbalance;

[0017] It is determined whether there are two groups of voltage limiter groups to be diagnosed whose corresponding current imbalance changes are greater than the second imbalance threshold value in each group of the voltage limiter groups. If so, the group with the larger current in the voltage limiter groups to be diagnosed is determined as the faulty voltage limiter group.

[0018] In one embodiment, the fault diagnosis method of the series compensation device voltage limiter further includes:

[0019] Monitor whether there is a sudden voltage limiter group with a sudden current change in each group of voltage limiter groups. If so, take the time period from the moment when the sudden current change occurs in the sudden voltage limiter group to the time when the current decreases to zero as the time period to be diagnosed; collect the current of each group of voltage limiter groups in the time period to be diagnosed;

[0020] Determine the current imbalance between the two voltage limiter groups in the time period to be diagnosed according to the current of each voltage limiter group in the time period to be diagnosed;

[0021] It is determined whether the maximum value of the current imbalance between the two voltage limiter groups within the time period to be diagnosed is greater than a third imbalance threshold value. If so, the sudden voltage limiter group is determined as a faulty voltage limiter group.

[0022] In one embodiment, determining the current imbalance between two voltage limiter groups according to the current of each voltage limiter group includes:

[0023] The current unbalance between voltage limiter group b and voltage limiter group p is determined according to the following formula:

[0024]

[0025] Wherein, I1 is the current of voltage limiter group b; I2 is the current of voltage limiter group p.

[0026] In one embodiment, the step of determining the change in current imbalance between the two voltage limiter groups according to the current imbalance between the two voltage limiter groups and the historical current imbalance includes:

[0027] Determine the current unbalance change I′ between voltage limiter group b and voltage limiter group p according to the following formula bp :

[0028]

[0029] Among them, I bp1 is the historical current imbalance between voltage limiter group b and voltage limiter group p; I bp is the current imbalance between voltage limiter group b and voltage limiter group p.

[0030] In a second aspect, the present application provides a fault diagnosis device for a series compensation device voltage limiter, comprising:

[0031] A collection module, used for collecting currents of multiple voltage limiter groups of a target series compensation device, wherein the target series compensation device comprises: multiple voltage limiter branches connected in parallel, each voltage limiter branch comprises: at least two voltage limiter groups connected in series in sequence;

[0032] A first imbalance determination module, configured to determine the current imbalance between any two voltage limiter groups according to the current of each group of the voltage limiter groups;

[0033] The first diagnostic module is used to diagnose whether the maximum value of the current imbalance between the two voltage limiter groups is greater than a first imbalance threshold. If so, the group with a larger current among the two voltage limiter groups corresponding to the maximum value of the current imbalance is determined as a faulty voltage limiter group.

[0034] In one embodiment, the fault diagnosis device for the series compensation device voltage limiter further includes:

[0035] An acquisition module, used for acquiring the historical current of each group of the voltage limiter groups acquired last time;

[0036] A second imbalance determination module is used to determine the historical current imbalance between any two voltage limiter groups according to the historical current of each group of the voltage limiter groups;

[0037] A change amount determination module, used for determining the change amount of the current imbalance between the two voltage limiter groups according to the current imbalance between the two voltage limiter groups and the historical current imbalance;

[0038] The second diagnostic module is used to determine whether there are two groups of voltage limiter groups to be diagnosed in each group of the voltage limiter groups whose corresponding current imbalance changes are greater than the second imbalance threshold. If so, the group with larger current in the voltage limiter groups to be diagnosed is determined as the faulty voltage limiter group.

[0039] In one embodiment, the fault diagnosis device for the series compensation device voltage limiter further includes:

[0040] A monitoring module is used to monitor whether there is a sudden voltage limiter group with a sudden current mutation in each group of voltage limiter groups. If so, the time period from the moment when the sudden current mutation occurs in the sudden voltage limiter group to the time when the current decreases to zero is used as the time period to be diagnosed; and the current of each group of voltage limiter groups in the time period to be diagnosed is collected;

[0041] A third imbalance determination module is used to determine the current imbalance between the two voltage limiter groups in the time period to be diagnosed according to the current of each voltage limiter group in the time period to be diagnosed;

[0042] The third diagnosis module is used to determine whether the maximum value of the current imbalance between the two voltage limiter groups in the diagnosis time period is greater than a third imbalance threshold value, and if so, determine the sudden voltage limiter group as a faulty voltage limiter group.

[0043] In one embodiment, the first imbalance determination module includes:

[0044] The determination unit is used to determine the current unbalance between the voltage limiter group b and the voltage limiter group p according to the following formula:

[0045]

[0046] Wherein, I1 is the current of voltage limiter group b; I2 is the current of voltage limiter group p.

[0047] In one embodiment, the variation determination module includes:

[0048] The variation determination unit is used to determine the current unbalance variation I′ between the voltage limiter group b and the voltage limiter group p according to the following formula bp :

[0049]

[0050] Among them, I bp1 is the historical current imbalance between voltage limiter group b and voltage limiter group p; I bpis the current imbalance between voltage limiter group b and voltage limiter group p.

[0051] In a third aspect, the present application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the fault diagnosis method for the series compensation device voltage limiter when executing the program.

[0052] In a fourth aspect, the present application provides a computer-readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement the fault diagnosis method for a voltage limiter of a series compensation device.

[0053] It can be seen from the above technical scheme that the present application provides a fault diagnosis method and device for a voltage limiter of a series compensation device. The method includes: collecting the current of multiple groups of voltage limiter groups of a target series compensation device, wherein the target series compensation device includes: multiple voltage limiter branches connected in parallel, each voltage limiter branch includes: at least two groups of the voltage limiter groups; determining the current imbalance between the two voltage limiter groups according to the current of each group of the voltage limiter groups; diagnosing whether the maximum value of the current imbalance between the two voltage limiter groups is greater than the set imbalance threshold, and if so, determining the group with the larger current in the two groups of voltage limiter groups corresponding to the maximum value of the current imbalance as the faulty voltage limiter group, which can improve the efficiency and timeliness of fault diagnosis on the basis of ensuring the accuracy of voltage limiter fault diagnosis; realizing the detection and prediction of early MOV faults, which can effectively guide the planned maintenance of series compensation equipment, prevent the expansion of faults, and reduce unplanned shutdown of series compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be 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.

[0055] Figure 1 It is a typical circuit structure diagram of a series compensation device in the prior art;

[0056] Figure 2 It is the unbalanced protection logic diagram of MOV branch in the prior art;

[0057] Figure 3 It is a schematic diagram of the MOV branch current waveform when a certain series compensation engineering MOV voltage limiting action is performed in the prior art;

[0058] Figure 4 It is a volt-ampere characteristic curve of a certain series compensation MOV in the prior art;

[0059] Figure 5 is a first flow chart of a method for diagnosing a fault of a voltage limiter of a series compensation device in an embodiment of the present application;

[0060] Figure 6 is a structural schematic diagram of a series compensation device in an embodiment of the present application;

[0061] Figure 7 is a topological diagram of a voltage limiter branch in an embodiment of the present application;

[0062] Figure 8 is a second flow chart of the fault diagnosis method of the voltage limiter of the series compensation device in the embodiment of the present application;

[0063] Fig. 9 is a third flow chart of a fault diagnosis method for a voltage limiter of a series compensation device in an embodiment of the present application;

[0064] Fig.10 It is a schematic diagram comparing the current waveform of a normal voltage limiter and the current waveform of a voltage limiter containing a faulty resistor in an application example of the present application;

[0065] Fig.11 is a structural schematic diagram of a fault diagnosis device for a series compensation device voltage limiter in an embodiment of the present application;

[0066] Fig.12 A schematic block diagram of the system structure of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0067] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0068] The voltage limiter plays a vital role in ensuring the safe operation of the series compensation device. Figure 1 It is a typical circuit structure diagram of a series compensation device in the prior art; Figure 1The dotted box in the middle represents the series compensation high-voltage platform, DBS is the bypass disconnector, ES1 and ES2 are the line grounding switches, DS1 and DS2 are the line disconnectors; CT1 is the series compensation current measurement current transformer; CT2 is the MOV1 branch current measurement current transformer; CT3 is the MOV2 branch current measurement current transformer; CT4 is the capacitor bank current measurement current transformer; CT5 is the capacitor bank unbalanced current measurement current transformer; CT6 is the platform current measurement current transformer; CT7 is the gap current measurement current transformer; C is the capacitor bank; D is the damping device; BS is the bypass switch; GAP is the spark gap. The MOV device is connected in parallel at both ends of the capacitor bank and is the capacitor bank protection device; the current flowing through the capacitor bank increases, and the voltage at both ends of the MOV connected in parallel increases. When the voltage exceeds the protection level of the MOV, current flows. In order to ensure the safety of the capacitor bank, the MOV capacity design must consider the maximum energy that may be absorbed under different line conditions; for this purpose, the MOV adopts a multi-resistance series and multi-column parallel structure, and each resistor and each column has consistent electrical characteristics; during the project implementation, each phase MOV column is divided into two groups, and each group is equipped with a branch current CT; under normal circumstances, the current distribution of the two MOV branches should be related to the number of parallel columns of each group of MOV, that is, I mov1 / I mov2 = Number of MOV1 columns / number of MOV2 columns; when the resistor inside the MOV is damaged, the current distribution of the two MOV branches changes.

[0069] Due to the large number of parallel columns and high installation position, there is currently a lack of effective warning methods for voltage limiter defects. Traditional voltage limiter fault diagnosis mainly relies on a single parameter of leakage current. However, the single parameter of leakage current is difficult to reflect the operating status of the voltage limiter used in series compensation devices.

[0070] The series compensation protection device is equipped with MOV branch unbalance protection, which collects the current of CT2 and CT3, calculates the current distribution flowing through the two MOV branches in real time, and determines the operating status of the MOV device. Figure 2 As shown, the protection logic is described as follows:

[0071] 1) The calculation method of MOV unbalance is:

[0072] MOV unbalance =(I mov1- I mov2 ×k) / (I mov1+ I mov2 ×k)

[0073] K = Number of MOV1 columns / Number of MOV2 columns

[0074] 2) When the MOV voltage limiting action is in progress, the MOV current waveform is usually an irregular spike with a short duration, such as Figure 3 As shown, for this protection criterion, "total current of the first-phase MOV" is an instantaneous value, and "unbalance degree of the first-phase MOV" is calculated using the instantaneous value.

[0075] 3) Figure 4 This is the volt-ampere characteristic curve of a MOV device in a series compensation project. It can be seen that when the MOV voltage is slightly greater than the protection level, the MOV current is small, and as the voltage increases, the current increases rapidly. Based on this feature, considering many factors such as the accuracy of the measurement system, the original imbalance of the MOV column current distribution, and the reliability of the instantaneous value criterion in engineering applications, the MOV unbalanced protection start-up setting is usually greater than the rated current of the series compensation device.

[0076] 4) When the line is fault-free, the voltage at the MOV terminal is relatively low, and the MOV branch current is a leakage current. At this time, the early defects of the MOV equipment are not easy to expose, and the MOV branch unbalance protection does not work; when the line fails, the MOV voltage limiter works, and the MOV energy accumulates rapidly, causing the MOV defect to be aggravated instantly, and the MOV branch unbalance protection works. It can be seen that when the MOV fails, the change in the unbalance degree is not slow and gradual, but a sudden change. For this reason, the MOV unbalance protection setting should not be set too low, usually not less than 30%.

[0077] Statistics on the operation data of a large number of series compensation equipment have been collected, and it is found that in actual projects, the unbalanced protection of MOV branches occurs when there is a fault in the line area, accompanied by damage to the MOV resistors of varying amounts and degrees. A large amount of energy is released rapidly when the resistors are damaged, which can affect adjacent equipment in severe cases, causing the scope of the fault to expand. If the number of damaged columns exceeds the number of spare columns, the entire MOV group will need to be replaced, and the series compensation will be shut down for a long time.

[0078] Combined with the statistical results, it can be seen that the existing series-compensated MOV branch unbalance protection is mainly aimed at serious faults of MOV equipment. The protection quickly acts to exit the series compensation and permanently lock the series compensation re-entry; this protection can prevent the equipment from being put into operation with faults, but it cannot achieve early fault detection and warning of MOV.

[0079] The existing series-compensated MOV branch unbalance protection is mainly aimed at serious failures of MOV equipment, and cannot detect and warn of early MOV failures. In theory, early MOV failures are mainly caused by defects in individual resistors, which cause deviations in the electrical characteristics of the two MOV branches: before the MOV voltage limiting action, it is reflected as a change in the distribution of branch leakage current, and during the voltage limiting action, it is reflected as a change in the distribution of branch current.

[0080] MOV voltage limiting action may occur when there is a fault within the line area, a near-end fault outside the area, or a system power oscillation. When there is a fault within the line area, MOV voltage limiting action occurs, and the MOV current is large. The existing MOV branch unbalance protection is designed for this situation. In the other two situations, MOV voltage limiting action occurs, and the MOV current is small, especially when the MOV voltage is close to the protection level. The existing MOV branch unbalance protection cannot handle the branch current distribution changes caused by MOV early faults. The main reasons are:

[0081] 1) The MOV branch current has a wide range of variation. In actual projects, the rated value of the branch current CT is usually the line current rated value. Therefore, Figure 1 The measurement accuracy of CT2 and CT3 for small currents is limited, and the existing protection schemes are difficult to accurately calculate the distribution of MOV branch currents under small current conditions.

[0082] 2) In order to ensure the balance of current distribution, the MOV poles need to be strictly balanced before leaving the factory, but there are still deviations. Table 1 shows the current distribution imbalance of a certain project MOV before leaving the factory.

[0083] Table 1

[0084]

[0085] The existing MOV branch unbalance protection algorithm calculates the imbalance of branch current in real time, and uses the deviation between the calculation result and the ideal state as the protection criterion. By improving the protection setting value, it reduces the influence of factors such as measurement accuracy and MOV current initial imbalance on the protection accuracy. Therefore, it is impossible to accurately judge the abnormal distribution of branch current under MOV low current, and then it is impossible to realize MOV early fault detection and prediction.

[0086] Based on the defects of the existing MOV branch unbalance protection scheme, the embodiment of the present application proposes a new fault diagnosis method and device for the voltage limiter of a series compensation device, which can cover the variation range of MOV current, judge the operating condition of the MOV by monitoring the variation trend of the MOV branch current imbalance, realize online monitoring and real-time data analysis of the voltage limiter, timely discover potential faults, realize the detection and prediction of early MOV faults, effectively guide the planned maintenance of the series compensation equipment, prevent the expansion of faults, reduce the unplanned shutdown of the series compensation, and improve the stability and reliability of the entire power system.

[0087] The embodiment of the present application can combine monitoring technology and data analysis algorithm to more accurately identify the fault of the voltage limiter. Compared with the traditional method, it can better distinguish the normal operation state and the fault state, and reduce the false alarm and missed alarm.

[0088] The embodiments of the present application can adopt digital transmission and optical fiber data transmission technology to enhance the anti-interference ability of the system. In a complex electromagnetic environment, the system can still operate stably and reliably to ensure the accuracy and real-time performance of fault diagnosis. In short, the embodiments of the present application can significantly improve the accuracy and efficiency of fault diagnosis, reduce maintenance costs, and improve the stability and reliability of the system. At the same time, it also has the characteristics of digitization, intelligence, and remote monitoring, which provides a strong guarantee for the safe operation of the power system.

[0089] The details are described through the following embodiments.

[0090] In order to improve the efficiency and timeliness of fault diagnosis while ensuring the accuracy of voltage limiter fault diagnosis, this embodiment provides a fault diagnosis method for a series compensation device voltage limiter, wherein the execution subject is a fault diagnosis device for a series compensation device voltage limiter, and the fault diagnosis device for the series compensation device voltage limiter includes but is not limited to a server, such as Figure 5 As shown, the method specifically includes the following contents:

[0091] Step 101: collecting currents of multiple voltage limiter groups of a target series compensation device, wherein the target series compensation device comprises: multiple voltage limiter branches connected in parallel, and each voltage limiter branch comprises: at least two voltage limiter groups.

[0092] Specifically, the current transformer corresponding to each voltage limiter group can be used to collect the current of the voltage limiter group; the target series compensation device can be as follows: Figure 6 As shown, Figure 6 Among them, MOV11, MOV12, MOV21 and MOV22 are all voltage limiter groups, each of which may include multiple voltage limiters; each voltage limiter group may include the same number of parallel branches; CT21 is the current transformer for measuring branch current of MOV11 group, CT22 is the current transformer for measuring branch current of MOV12 group, CT31 is the current transformer for measuring branch current of MOV21 group, and CT32 is the current transformer for measuring branch current of MOV22 group. Figure 6 and Figure 7 As shown, the target series compensation device may include: a voltage limiter branch composed of CT2, CT21, CT22, MOV11 and MOV12, and a voltage limiter branch composed of CT3, CT31, CT32, MOV21 and MOV22. Figure 7 HV stands for high voltage, and LV stands for low voltage.

[0093] Step 102: Determine the current imbalance between any two voltage limiter groups according to the current of each voltage limiter group.

[0094] Specifically, the current unbalance degree between any two voltage limiter groups may be determined according to the currents of the two voltage limiter groups.

[0095] Step 103: diagnose whether the maximum value of the current imbalance between the two voltage limiter groups is greater than a first imbalance threshold; if so, determine the voltage limiter group with a larger current among the two voltage limiter groups corresponding to the maximum value of the current imbalance as a faulty voltage limiter group.

[0096] Specifically, the fault voltage limiter group may represent a voltage limiter group having a faulty resistor.

[0097] In order to improve the sensitivity of fault diagnosis of voltage limiter, Figure 8 As shown, in one embodiment, the fault diagnosis method of the series compensation device voltage limiter further includes:

[0098] Step 201: Acquire the historical current of each group of the voltage limiter groups collected last time.

[0099] Specifically, the historical current of each group of the voltage limiter groups collected last time may be the current of each group of the voltage limiter groups collected before step 101 .

[0100] Step 202: determining the historical current imbalance between two voltage limiter groups according to the historical current of each voltage limiter group; correspondingly, after step 102, the following steps are included:

[0101] Step 203: Determine the change in current imbalance between the two voltage limiter groups according to the current imbalance between the two voltage limiter groups and the historical current imbalance.

[0102] Specifically, the historical current imbalance can represent the current imbalance between two voltage limiter groups determined according to the historical current of each voltage limiter group. The change in current imbalance between any two voltage limiter groups can be determined according to the current imbalance between the two voltage limiter groups and the historical current imbalance.

[0103] Step 204: determine whether there are two groups of voltage limiter groups to be diagnosed whose corresponding current imbalance changes are greater than the second imbalance threshold value in each group of the voltage limiter groups; if so, determine the group with the larger current in the voltage limiter groups to be diagnosed as the faulty voltage limiter group.

[0104] Specifically, the second imbalance threshold may be smaller than the first imbalance threshold.

[0105] In order to further improve the sensitivity of voltage limiter fault diagnosis, Fig. 9 As shown, in one embodiment, the fault diagnosis method of the series compensation device voltage limiter further includes:

[0106] Step 301: monitor whether there is a sudden voltage limiter group with a current mutation in each voltage limiter group. If so, take the time period from the moment when the current mutation occurs to the time when the current decreases to zero as the time period to be diagnosed; collect the current of each voltage limiter group in the time period to be diagnosed.

[0107] Step 302: Determine the current imbalance between any two voltage limiter groups in the time period to be diagnosed according to the current of each voltage limiter group in the time period to be diagnosed.

[0108] Step 303: determine whether the maximum value of the current imbalance between any two voltage limiter groups within the time period to be diagnosed is greater than a third imbalance threshold; if so, determine the sudden voltage limiter group as a faulty voltage limiter group.

[0109] Specifically, the third unbalance threshold may be smaller than the second unbalance threshold. The warning information corresponding to the faulty voltage limiter group obtained in step 103, step 204 and step 303 may also be output and displayed to facilitate the maintenance of the series compensation device.

[0110] In order to improve the reliability of the current imbalance, in one embodiment, step 102 includes:

[0111] The current unbalance between voltage limiter group b and voltage limiter group p is determined according to the following formula:

[0112]

[0113] Wherein, I1 is the current of voltage limiter group b; I2 is the current of voltage limiter group p. Voltage limiter group b can represent any voltage limiter group among the plurality of voltage limiter groups, and voltage limiter group p can represent any voltage limiter group among the plurality of voltage limiter groups except voltage limiter group b. The historical current unbalance between voltage limiter group b and voltage limiter group p can be obtained by referring to the method for determining the current unbalance.

[0114] In order to improve the reliability of the change in the current imbalance, in one embodiment, step 203 includes:

[0115] Determine the current unbalance change I′ between voltage limiter group b and voltage limiter group p according to the following formula bp :

[0116]

[0117] Among them, I bp1 is the historical current imbalance between voltage limiter group b and voltage limiter group p; I bp is the current imbalance between voltage limiter group b and voltage limiter group p.

[0118] To further illustrate the present scheme, the present application is based on the current difference between normal and damaged MOV groups under overvoltage conditions of the capacitor group. The present application proposes an application example of a fault diagnosis method for a series compensation device voltage limiter. The capacitor group has a large capacity and a high voltage. In order to ensure the protection effect of the MOV, multiple MOVs are connected in series as columns and multiple parallel structures are used. In this application example, the MOV branches in parallel for each phase are divided into multiple groups. A current transformer is connected in series to each group to measure the total current of the MOV in this group. Because the MOVs that protect the series compensation have strict unbalance requirements and are subjected to balancing tests, the current waveforms between normal MOV groups are basically the same. However, after a certain MOV is damaged, the overall VI characteristics of the MOV group will change. When the terminal voltage is consistent, the current waveforms of the faulty MOV group and the normal MOV group are different. When the system is operating normally, the current of MOV is very small, and the difference in current of each group of MOV is difficult to distinguish; but when a short circuit fault occurs in the system, the terminal voltage of the series capacitor rises rapidly, which is several times the rated voltage, and the current difference between the faulty group and the normal group of MOV will increase. The current imbalance can be calculated by real-time monitoring of the current value and setting the setting value. When the calculated current imbalance value reaches above the setting value, it can be determined that there is a faulty resistor in the group of voltage limiters with large current. The specific description is as follows:

[0119] The voltage limiter branches of the series compensation device are divided into multiple groups, each of which is equipped with a current transformer, such as Figure 6 As shown, the voltage limiter is divided into four groups, namely, MOV11, MOV12, MOV21, and MOV22. Each group of main outgoing lines is equipped with a current transformer, namely, CT21, CT22, CT31, and CT32.

[0120] When a fault occurs in the line where the series compensation device is located, the current flowing through the capacitor group increases, and the voltage across the MOV unit connected in parallel increases. The MOV unit can be equivalent to the above-mentioned voltage limiter group. When the voltage exceeds the inflection point voltage of the MOV unit, part of the fault current will flow through the MOV unit. The protection device collects data from each group of current transformers, calculates the imbalance of each group of MOV units, and determines the condition of the resistor in the MOV unit. The strategy for voltage limiter fault diagnosis is to make a judgment based on the current imbalance under fault conditions. There are three ways to diagnose imbalance:

[0121] Method 1: Horizontal comparison of current unbalance: Horizontally compare multiple groups of current values, that is, calculate the current unbalance through the currents measured by CT21, CT22, CT31, and CT32. Consider CT measurement accuracy and MOV manufacturing error, and set a reasonable current unbalance setting value in combination with MOV matching test results.

[0122] Current imbalance I bp The calculation formula is:

[0123]

[0124] Where: I1 is the total current of one group of voltage limiters; I2 is the total current of one group of voltage limiters in the remaining three groups.

[0125] By comparing the data between two groups, the maximum value of the current imbalance between groups can be obtained. For example, if the constant value is set to 8%, the current of multiple groups of voltage limiters is monitored. When the maximum value of the current imbalance exceeds 8%, it can be determined that a group of voltage limiters with large current has a faulty piece.

[0126] Method 2: Longitudinal comparison of current imbalance: that is, compare the current imbalance with the historical imbalance and calculate the change in current imbalance.

[0127] Current unbalance change I' bp The calculation formula is:

[0128]

[0129] Where: I bp1 is the last current imbalance; I bp is the current imbalance.

[0130] Under normal circumstances, the current imbalance of the voltage limiter is related to factors such as CT measurement accuracy and MOV manufacturing error. After the voltage increases, the current imbalance is a stable data. However, after a resistor failure occurs in a group of voltage limiters, the current imbalance will change. Calculating the change in current imbalance is more sensitive than method 1, and problems that method 1 does not find can be found. The setting value can be smaller than the certain value of the scheme.

[0131] For example, if the constant is set to 5%, when the change in current imbalance calculated twice exceeds 5%, it can be determined that a faulty piece has appeared in the voltage limiter. By comparing the current values ​​of the two groups of voltage limiters, it can be determined that the faulty piece is in the group of voltage limiters with larger current.

[0132] Method 3: Abnormal current mutation lateral comparison of current imbalance: When the voltage limiter is activated, the branch current has an abnormal mutation. That is, when a short circuit occurs in the system, the MOV has to withstand high current and high voltage, which may accelerate the damage of the resistor with potential faults. In the simulation process, the current waveform of this situation can be obtained, such as Fig.10 As shown in the figure, in the time period from 0.3075S to 0.3100S, the current waveform of the voltage limiter group containing the resistor breakdown after the fault suddenly increased and then decreased during the original reduction process, while the current of other groups did not change in this way. Fig.10 The A waveform in the figure represents the current waveform of the voltage limiter group with the resistor breakdown after the fault, and the B waveform represents the current waveform of the normal voltage limiter group.

[0133] The specific method is to use the method 1 to calculate the current imbalance after finding that the current of a certain group of voltage limiters increases during the decline period. Since the specific interval of current change is added when calculating the current imbalance, the sensitivity is higher and the setting value can be set lower than the horizontal comparison current imbalance of method 1. For example, if the setting value is set to 3%, when the current of a certain group of voltage limiters suddenly increases during the decline period, and the maximum value of the current imbalance of the voltage limiters between the groups reaches above the setting value, it can be judged that there is a faulty resistor in the group of voltage limiters with increased current.

[0134] At the same time, the constants of the above schemes can be set to different values ​​according to the size of the primary current. For example, the current can be divided into two ranges, and the constants of each range are different. This can also effectively avoid CT errors and improve sensitivity.

[0135] From the above description, it can be seen that the fault diagnosis method of the series compensation device voltage limiter provided in this application example can adopt a variety of current imbalance comparison methods, including horizontal comparison of current imbalance, vertical comparison of current imbalance, and horizontal comparison of current abnormal mutation. Through real-time monitoring and analysis of branch currents, the fault of the voltage limiter can be identified more accurately; intelligent fault diagnosis algorithms can also be applied, which can automatically analyze monitoring data, identify abnormal characteristics, and accurately identify faults, thereby improving the efficiency and accuracy of fault diagnosis.

[0136] From the software level, in order to improve the efficiency and timeliness of fault diagnosis while ensuring the accuracy of voltage limiter fault diagnosis, the present application provides an embodiment of a fault diagnosis device for a series compensation device voltage limiter for realizing all or part of the contents of the fault diagnosis method for a series compensation device voltage limiter, see Fig.11 The fault diagnosis device of the series compensation device voltage limiter specifically includes the following contents:

[0137] The acquisition module 01 is used to acquire currents of multiple voltage limiter groups of a target series compensation device, wherein the target series compensation device comprises: multiple voltage limiter branches connected in parallel, each voltage limiter branch comprises: at least two voltage limiter groups connected in series in sequence;

[0138] A first imbalance determination module 02, configured to determine the current imbalance between any two voltage limiter groups according to the current of each voltage limiter group;

[0139] The first diagnostic module 03 is used to diagnose whether the maximum value of the current imbalance between the two voltage limiter groups is greater than a first imbalance threshold. If so, the group with a larger current among the two voltage limiter groups corresponding to the maximum value of the current imbalance is determined as a faulty voltage limiter group.

[0140] In one embodiment, the fault diagnosis device for the series compensation device voltage limiter further includes:

[0141] An acquisition module, used for acquiring the historical current of each group of the voltage limiter groups acquired last time;

[0142] A second imbalance determination module is used to determine the historical current imbalance between any two voltage limiter groups according to the historical current of each group of the voltage limiter groups;

[0143] A change amount determination module, used for determining the change amount of the current imbalance between the two voltage limiter groups according to the current imbalance between the two voltage limiter groups and the historical current imbalance;

[0144] The second diagnostic module is used to determine whether there are two groups of voltage limiter groups to be diagnosed in each group of the voltage limiter groups whose corresponding current imbalance changes are greater than the second imbalance threshold. If so, the group with larger current in the voltage limiter groups to be diagnosed is determined as the faulty voltage limiter group.

[0145] In one embodiment, the fault diagnosis device for the series compensation device voltage limiter further includes:

[0146] A monitoring module is used to monitor whether there is a sudden voltage limiter group with a sudden current mutation in each group of voltage limiter groups. If so, the time period from the moment when the sudden current mutation occurs in the sudden voltage limiter group to the time when the current decreases to zero is used as the time period to be diagnosed; and the current of each group of voltage limiter groups in the time period to be diagnosed is collected;

[0147] A third imbalance determination module is used to determine the current imbalance between the two voltage limiter groups in the time period to be diagnosed according to the current of each voltage limiter group in the time period to be diagnosed;

[0148] The third diagnosis module is used to determine whether the maximum value of the current imbalance between the two voltage limiter groups in the diagnosis time period is greater than a third imbalance threshold value, and if so, determine the sudden voltage limiter group as a faulty voltage limiter group.

[0149] In one embodiment, the first imbalance determination module includes:

[0150] The determination unit is used to determine the current unbalance between the voltage limiter group b and the voltage limiter group p according to the following formula:

[0151]

[0152] Wherein, I1 is the current of voltage limiter group b; I2 is the current of voltage limiter group p.

[0153] In one embodiment, the variation determination module includes:

[0154] The variation determination unit is used to determine the current unbalance variation I′ between the voltage limiter group b and the voltage limiter group p according to the following formula bp:

[0155]

[0156] Among them, I bp1 is the historical current imbalance between voltage limiter group b and voltage limiter group p; I bp is the current imbalance between voltage limiter group b and voltage limiter group p.

[0157] The embodiment of the fault diagnosis device for a series compensation device voltage limiter provided in this specification can be specifically used to execute the processing flow of the embodiment of the fault diagnosis method for a series compensation device voltage limiter mentioned above. Its functions will not be repeated here, and reference can be made to the detailed description of the embodiment of the fault diagnosis method for a series compensation device voltage limiter mentioned above.

[0158] Fig.12 A schematic diagram of the physical structure of an electronic device provided in an embodiment of the present invention, such as Fig.12 As shown, the electronic device includes: a memory 1201, a processor 1202, and a computer program stored in the memory 1201 and executable on the processor 1202. When the processor 1202 executes the computer program, the following method is implemented:

[0159] Collecting currents of multiple voltage limiter groups of a target series compensation device, wherein the target series compensation device comprises: multiple voltage limiter branches connected in parallel, each voltage limiter branch comprises: at least two of the voltage limiter groups;

[0160] Determining the current imbalance between two voltage limiter groups according to the current of each voltage limiter group;

[0161] It is diagnosed whether the maximum value of the current imbalance between the two voltage limiter groups is greater than a set imbalance threshold value. If so, the group with a larger current among the two voltage limiter groups corresponding to the maximum value of the current imbalance is determined as a faulty voltage limiter group.

[0162] This embodiment discloses a computer program product, the computer program product including a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0163] Collecting currents of multiple voltage limiter groups of a target series compensation device, wherein the target series compensation device comprises: multiple voltage limiter branches connected in parallel, each voltage limiter branch comprises: at least two of the voltage limiter groups;

[0164] Determining the current imbalance between two voltage limiter groups according to the current of each voltage limiter group;

[0165] It is diagnosed whether the maximum value of the current imbalance between the two voltage limiter groups is greater than a set imbalance threshold value. If so, the group with a larger current among the two voltage limiter groups corresponding to the maximum value of the current imbalance is determined as a faulty voltage limiter group.

[0166] This embodiment provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the following method is implemented:

[0167] Collecting currents of multiple voltage limiter groups of a target series compensation device, wherein the target series compensation device comprises: multiple voltage limiter branches connected in parallel, each voltage limiter branch comprises: at least two of the voltage limiter groups;

[0168] Determining the current imbalance between two voltage limiter groups according to the current of each voltage limiter group;

[0169] It is diagnosed whether the maximum value of the current imbalance between the two voltage limiter groups is greater than a set imbalance threshold value. If so, the group with a larger current among the two voltage limiter groups corresponding to the maximum value of the current imbalance is determined as a faulty voltage limiter group.

[0170] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0171] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0172] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0173] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0174] In the description of this specification, the description with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0175] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fault diagnosis method for a voltage limiter of a series compensation device, characterized in that: include: Collecting currents of multiple voltage limiter groups of a target series compensation device, wherein the target series compensation device comprises: multiple voltage limiter branches connected in parallel, each voltage limiter branch comprises: at least two of the voltage limiter groups; Determining the current imbalance between two voltage limiter groups according to the current of each voltage limiter group; It is diagnosed whether the maximum value of the current imbalance between the two voltage limiter groups is greater than a first imbalance threshold value. If so, the group with a larger current among the two voltage limiter groups corresponding to the maximum value of the current imbalance is determined as a faulty voltage limiter group.

2. The fault diagnosis method of the voltage limiter of the series compensation device according to claim 1, characterized in that: Also includes: Obtaining the historical current of each group of the voltage limiter groups collected last time; Determining the historical current imbalance between any two voltage limiter groups according to the historical current of each voltage limiter group; Correspondingly, after determining the current imbalance between the two voltage limiter groups according to the current of each group of the voltage limiter groups, the method further includes: Determine the change amount of the current unbalance between the two voltage limiter groups according to the current unbalance between the two voltage limiter groups and the historical current unbalance; It is determined whether there are two groups of voltage limiter groups to be diagnosed whose corresponding current imbalance changes are greater than the second imbalance threshold value in each group of the voltage limiter groups. If so, the group with the larger current in the voltage limiter groups to be diagnosed is determined as the faulty voltage limiter group.

3. The fault diagnosis method of the voltage limiter of the series compensation device according to claim 1, characterized in that: Also includes: Monitor whether there is a sudden voltage limiter group with a sudden current change in each group of voltage limiter groups. If so, take the time period from the moment when the sudden current change occurs in the sudden voltage limiter group to the time when the current decreases to zero as the time period to be diagnosed; collect the current of each group of voltage limiter groups in the time period to be diagnosed; Determine the current imbalance between the two voltage limiter groups in the time period to be diagnosed according to the current of each voltage limiter group in the time period to be diagnosed; It is determined whether the maximum value of the current imbalance between the two voltage limiter groups within the time period to be diagnosed is greater than a third imbalance threshold value. If so, the sudden voltage limiter group is determined as a faulty voltage limiter group.

4. The fault diagnosis method of the voltage limiter of the series compensation device according to claim 1, characterized in that: The step of determining the current imbalance between two voltage limiter groups according to the current of each voltage limiter group includes: The current unbalance between voltage limiter group b and voltage limiter group p is determined according to the following formula: Wherein, I1 is the current of voltage limiter group b; I2 is the current of voltage limiter group p.

5. The fault diagnosis method of the voltage limiter of the series compensation device according to claim 2, characterized in that: The step of determining the change in the current imbalance between the two voltage limiter groups according to the current imbalance between the two voltage limiter groups and the historical current imbalance includes: Determine the current unbalance change I′ between voltage limiter group b and voltage limiter group p according to the following formula bp : Among them, I bp1 is the historical current imbalance between voltage limiter group b and voltage limiter group p; I bp is the current imbalance between voltage limiter group b and voltage limiter group p.

6. A fault diagnosis device for a voltage limiter of a series compensation device, characterized in that: include: A collection module, used for collecting currents of multiple voltage limiter groups of a target series compensation device, wherein the target series compensation device comprises: multiple voltage limiter branches connected in parallel, each voltage limiter branch comprises: at least two voltage limiter groups connected in series in sequence; A first imbalance determination module, configured to determine the current imbalance between any two voltage limiter groups according to the current of each group of the voltage limiter groups; The first diagnostic module is used to diagnose whether the maximum value of the current imbalance between the two voltage limiter groups is greater than a first imbalance threshold. If so, the group with a larger current among the two voltage limiter groups corresponding to the maximum value of the current imbalance is determined as a faulty voltage limiter group.

7. The fault diagnosis device for the voltage limiter of the series compensation device according to claim 6, characterized in that: Also includes: An acquisition module, used for acquiring the historical current of each group of the voltage limiter groups acquired last time; A second imbalance determination module is used to determine the historical current imbalance between any two voltage limiter groups according to the historical current of each group of the voltage limiter groups; A change amount determination module, used for determining the change amount of the current imbalance between the two voltage limiter groups according to the current imbalance between the two voltage limiter groups and the historical current imbalance; The second diagnostic module is used to determine whether there are two groups of voltage limiter groups to be diagnosed in each group of the voltage limiter groups whose corresponding current imbalance changes are greater than the second imbalance threshold. If so, the group with larger current in the voltage limiter groups to be diagnosed is determined as the faulty voltage limiter group.

8. The fault diagnosis device for the voltage limiter of the series compensation device according to claim 6, characterized in that: Also includes: A monitoring module is used to monitor whether there is a sudden voltage limiter group with a sudden current mutation in each group of voltage limiter groups. If so, the time period from the moment when the sudden current mutation occurs in the sudden voltage limiter group to the time when the current decreases to zero is used as the time period to be diagnosed; and the current of each group of voltage limiter groups in the time period to be diagnosed is collected; A third imbalance determination module is used to determine the current imbalance between the two voltage limiter groups in the time period to be diagnosed according to the current of each voltage limiter group in the time period to be diagnosed; The third diagnosis module is used to determine whether the maximum value of the current imbalance between the two voltage limiter groups in the diagnosis time period is greater than a third imbalance threshold value, and if so, determine the sudden voltage limiter group as a faulty voltage limiter group.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the fault diagnosis method for the voltage limiter of the series compensation device according to any one of claims 1 to 5 is implemented.

10. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the instructions are executed by the processor, the fault diagnosis method for the voltage limiter of the series compensation device according to any one of claims 1 to 5 is implemented.

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