Equipment abnormity early warning method and system based on three-phase current and voltage imbalance

Abstract

The invention relates to the technical field of power equipment monitoring, and discloses an equipment abnormity early warning method and system based on three-phase current and voltage imbalance analysis, and the method comprises the steps: collecting an initial three-phase current and an initial three-phase voltage; determining an equipment type according to the initial three-phase current and the initial three-phase voltage; removing three-phase current and three-phase voltage which can be changed during operation of the circuit breaker / disconnecting switch and three-phase current and three-phase voltage of which the numerical values are 0 and negative in any time period from the initial three-phase current and the initial three-phase voltage; respectively calculating a first unbalance degree, a second unbalance degree, a third unbalance degree and a deviation degree of each device based on the final three-phase current and the final three-phase voltage; and whether the final three-phase current and the final three-phase voltage are abnormal or not is judged according to the first unbalance degree, the second unbalance degree and the third unbalance degree on the basis of a set abnormity judgment rule. According to the invention, early warning can be given out for abnormal equipment in advance, and relevant professionals are reminded to strengthen attention.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment monitoring, and in particular to a method and system for early warning of equipment abnormality based on three-phase current and voltage imbalance. Background Art

[0002] Current and voltage are important measurement information of the power grid, which contain rich equipment status information. However, the current analysis and application of three-phase current and voltage of power grid equipment are mainly concentrated in over-limit alarm and relay protection. Over-limit alarm requires setting clear thresholds. When the current and voltage values ​​exceed or fall below the threshold, an alarm is issued. When a power grid equipment fails, if the current and voltage meet the relay protection action value requirements, a trip will occur. Both of the above analysis applications have strict and clear thresholds and judgment rules, and are mainly in-process and post-event behaviors.

[0003] The actual situation is that the current and voltage values ​​of power grid equipment may not meet the over-limit alarm threshold requirements or tripping requirements within a few hours before a fault occurs, but they often show some abnormal characteristics in terms of three-phase current imbalance and three-phase voltage imbalance. There is currently no unified standard for using the unbalanced characteristics of three-phase current and voltage to warn of equipment abnormalities. It is of great significance to extract these abnormal characteristics in advance, discover potential defects and hidden dangers of equipment in advance, and issue alarms so that professionals such as monitoring, operation and maintenance can make plans and minimize the maintenance costs and power outage losses caused by equipment failures. Summary of the invention

[0004] The present invention provides an equipment abnormality early warning method and system based on three-phase current and voltage imbalance analysis. Through the imbalance analysis of the equipment's three-phase current and voltage, the characteristics of equipment defects, hidden dangers, deterioration or impending failures are discovered, thereby issuing an early warning to provide technical support for equipment monitoring, operation and maintenance, and repair personnel. The analysis and early warning method can serve as a powerful supplement to equipment status assessment methods such as online monitoring, live detection, and on-site inspections.

[0005] The present invention is achieved through the following technical solutions:

[0006] A device abnormality early warning method based on three-phase current and voltage imbalance, comprising:

[0007] S1, collecting initial three-phase current and initial three-phase voltage;

[0008] S2. Determine the device type according to the initial three-phase current and the initial three-phase voltage;

[0009] S3, removing the three-phase current and three-phase voltage that will change during the operation of the circuit breaker / disconnector and the current and three-phase voltage that are 0 and negative in any period from the initial three-phase current and initial three-phase voltage, the final three-phase current is composed of three final phase currents, and the final three-phase voltage is composed of three final phase voltages;

[0010] S4, calculating the first unbalance, the second unbalance, the third unbalance and the deviation of each device based on the final three-phase current and the final three-phase voltage;

[0011] S5. Determine whether the final three-phase current and / or final three-phase voltage are abnormal based on the set abnormal judgment rules according to the imbalance degree 1, imbalance degree 2, and imbalance degree 3. If so, determine the abnormal level of the final three-phase current and / or final three-phase voltage and directionally output the abnormal final three-phase current and / or final three-phase voltage and the time range corresponding to the abnormal final three-phase current and / or final three-phase voltage. Then, identify the phase that may have the abnormality according to the deviation degree of the abnormal final three-phase current and / or final three-phase voltage, and then return to S1. Otherwise, directly return to S1 to continue monitoring the equipment.

[0012] As an optimization, the imbalance degree 1, imbalance degree 2, imbalance degree 3 and deviation degree include current imbalance degree 1, current imbalance degree 2, current imbalance degree 3, current deviation degree and voltage imbalance degree 1, voltage imbalance degree 2, voltage imbalance degree 3, voltage deviation degree.

[0013] As an optimization, the specific formula of the current imbalance degree IB1 at the same time is:

[0014] IB1=(maxI i -minI i ) / maxI i ;

[0015] Among them, i∈[A, B, C], maxI i Indicates the maximum phase current among the final three-phase currents, minI i represents the smallest phase current among the final three-phase currents, and maxI i and minI i The final three-phase current, I i represents the i-th phase current in the final three-phase current;

[0016] The specific formula of the current imbalance degree IB2 at the same time is:

[0017]

[0018] in, It represents the arithmetic mean of the three phase currents in the final three-phase current, that is, the three-phase average current, I i represents the i-th phase current in the final three-phase current, i∈[A, B, C];

[0019] The specific formula of the current imbalance degree IB3 at the same time is:

[0020]

[0021] The current deviation ID of the final phase current of the i-th phase i The specific formula is:

[0022]

[0023] ID i represents the current deviation of the final phase current of the i-th phase, j∈[A, B, C] and j≠i;

[0024] The specific formula of the voltage imbalance degree VB1 at the same time is:

[0025] VB1=(maxV i -minV i ) / maxV i ;

[0026] Among them, i∈[A, B, C], maxV i Indicates the maximum phase voltage among the final three-phase voltages, minV i represents the minimum phase voltage among the final three-phase voltages, and maxVI i and minV i The final three-phase voltage, V i represents the i-th phase voltage in the final three-phase voltage;

[0027] The specific formula of the voltage imbalance degree VB2 at the same time is:

[0028]

[0029] in, It represents the arithmetic mean of the three phase voltages in the final three-phase voltage, that is, the three-phase average voltage, V i represents the i-th phase voltage in the final three-phase voltage, i∈[A, B, C];

[0030] The specific formula of the voltage imbalance degree IB3 at the same time is:

[0031]

[0032] The voltage deviation VD of the final phase voltage of the i-th phasei The specific formula is:

[0033]

[0034] Among them, VD i Represents the voltage deviation degree of the final phase voltage of the i-th phase, j∈[A, B, C] and j≠i.

[0035] As an optimization, the abnormality judgment rule includes a threshold over-limit warning type judgment rule, specifically:

[0036] If any of the current imbalance degree 1 IB1, the current imbalance degree 2 IB2, and the current imbalance degree 3 IB3 exceeds the current warning threshold, the final three-phase current is determined to be abnormal, and a three-phase current imbalance threshold exceeding warning is issued;

[0037] If any one of the voltage imbalance degree 1 VB1, the voltage imbalance degree 2 VB2, and the voltage imbalance degree 3 VB3 exceeds the voltage warning threshold, the final three-phase voltage is determined to be abnormal, and a three-phase voltage imbalance threshold exceeding warning is issued.

[0038] As an optimization, the abnormality judgment rule includes a recent sudden increase warning type judgment rule, specifically:

[0039] If the relative difference between the cumulative average value of any one of the current imbalance degree IB1, the current imbalance degree IB2, and the current imbalance degree IB3 from the first previous moment to the current moment and the cumulative average value of the corresponding current imbalance degree from the second previous moment to the first previous moment is not less than the first current difference threshold, let the relative difference be the first current relative difference, and if any one of the current imbalance degree IB1, the current imbalance degree IB2, and the current imbalance degree IB3 from the first previous moment to the current moment is greater than the cumulative average value of the corresponding current imbalance degree from the second previous moment to the first previous moment, then it is determined that the final three Phase current is abnormal, and a recent sudden increase warning is issued, wherein the first previous moment is before the current moment, the second previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, the absolute value of the time difference between the second previous moment and the first previous moment is greater than or equal to 24 hours and less than or equal to 72 hours, and the first current relative difference = (the cumulative average value of the current imbalance from the first previous moment to the current moment - the cumulative average value of the current imbalance from the second previous moment to the first previous moment) / the cumulative average value of the current imbalance from the second previous moment to the first previous moment * 100%;

[0040] If the relative difference between the cumulative average value of any one of the voltage imbalance degree VB1, the voltage imbalance degree VB2, and the voltage imbalance degree VB3 from the first previous moment to the current moment and the cumulative average value of the corresponding voltage imbalance degree from the second previous moment to the first previous moment is not less than the first voltage difference threshold, let the relative difference be the first voltage relative difference, and if any one of the voltage imbalance degree VB1, the voltage imbalance degree VB2, and the voltage imbalance degree VB3 from the first previous moment to the current moment is greater than the cumulative average value of the corresponding voltage imbalance degree from the second previous moment to the first previous moment, then it is determined that the final three The phase voltage is abnormal, and a recent sudden increase warning is issued, wherein the first previous moment is before the current moment, the second previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, the absolute value of the time difference between the second previous moment and the first previous moment is greater than or equal to 24 hours and less than or equal to 72 hours, and the first voltage relative difference = (the cumulative average value of the voltage imbalance from the first previous moment to the current moment - the cumulative average value of the voltage imbalance from the second previous moment to the first previous moment) / the cumulative average value of the voltage imbalance from the second previous moment to the first previous moment * 100%.

[0041] As an optimization, the abnormality judgment rule includes a historical mean over-limit warning type judgment rule, specifically:

[0042] If the relative difference between the cumulative average value of any one of the current imbalance degree IB1, the current imbalance degree IB2, and the current imbalance degree IB3 from the first previous moment to the current moment and the corresponding cumulative average value of the current imbalance degree from the third previous moment to the current moment is not less than the second current difference threshold, let the relative difference be the second current relative difference, wherein the first previous moment is before the current moment, the third previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, and the absolute value of the time difference between the third previous moment and the current moment ranges from 180 to 366 days, then it is determined that the final three-phase current is abnormal, and a historical average value over-limit warning is issued, and the second current relative difference = (the cumulative average value of the voltage imbalance from the first previous moment to the current moment - the cumulative average value of the voltage imbalance from the third previous moment to the current moment) / the cumulative average value of the voltage imbalance from the third previous moment to the current moment * 100%;

[0043] If the relative difference between the cumulative average value of any one of the voltage imbalance degree VB1, the voltage imbalance degree VB2, and the voltage imbalance degree VB3 from the first previous moment to the current moment and the corresponding cumulative average value of the voltage imbalance degree from the third previous moment to the current moment is not less than the second voltage difference threshold, let the relative difference be the second voltage relative difference, wherein the first previous moment is before the current moment, the third previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, and the absolute value of the time difference between the third previous moment and the current moment ranges from 180 to 366 days, then it is determined that the final three-phase voltage is abnormal, and a historical average value over-limit warning is issued, and the second voltage relative difference=(the cumulative average value of the voltage imbalance degree from the first previous moment to the current moment-the cumulative average value of the voltage imbalance degree from the third previous moment to the current moment) / the cumulative average value of the voltage imbalance degree from the third previous moment to the current moment*100%.

[0044] As an optimization, the abnormality judgment rule includes a long-term continuous growth warning type judgment rule, specifically:

[0045] If the daily average value of any current imbalance degree among the current imbalance degree 1 IB1, the current imbalance degree 2 IB2 and the current imbalance degree 3 IB3 shows a continuous growth trend in the M days from the current moment, it is determined that the final three-phase current is abnormal, and a long-term continuous current growth warning is issued, where M is a positive integer;

[0046] If the daily average value of any one of the voltage imbalance degrees VB1, VB2 and VB3 shows a continuous growth trend in the M days near the current moment, the final three-phase voltage is determined to be abnormal, and a long-term continuous voltage growth warning is issued.

[0047] As an optimization, the abnormality judgment rule includes a short-term continuous growth warning type judgment rule, specifically:

[0048] If the average value of any current imbalance degree among the current imbalance degree 1 IB1, the current imbalance degree 2 IB2 and the current imbalance degree 3 IB3 shows a continuous growth trend along the time axis in R time intervals with a time interval of N minutes and nearly P hours from the current moment, and the average value of the current imbalance degree in the time interval closest to the current moment is at least 1.5 times the average value of the current imbalance degree in the time interval farthest from the current moment, then it is determined that the final three-phase current is abnormal, and a short-term continuous current growth warning is issued, and P, N, and R are positive integers;

[0049] If the average value of the voltage imbalance of any one of the voltage imbalance VB1, voltage imbalance VB2 and voltage imbalance VB3 in R time intervals with a time interval of N minutes and nearly P hours from the current moment shows a continuous increasing trend along the time axis, and the average value of the voltage imbalance in the time interval closest to the current moment is at least 1.5 times the average value of the voltage imbalance in the time interval farthest from the current moment, then the final three-phase voltage is determined to be abnormal, and a short-term continuous voltage increase warning is issued, and P, N, and R are positive integers.

[0050] As an optimization, in S5, the specific process of identifying the phases that may have abnormalities according to the deviation of the abnormal final three-phase current and / or the final three-phase voltage is as follows:

[0051] Compare the three deviations of the abnormal final three-phase current and / or final three-phase voltage, and take the current and / or voltage of the phase with the largest absolute value of the deviation as the abnormal phase. If the deviation is a negative value, the current and / or voltage of the abnormal phase is a current and / or voltage that is too small. If the deviation is a positive value, the current and / or voltage of the abnormal phase is a current and / or voltage that is too large.

[0052] The present invention also discloses an equipment abnormality early warning system based on three-phase current and voltage imbalance analysis, comprising:

[0053] A collection module, used for collecting initial three-phase current and initial three-phase voltage;

[0054] An equipment classification module determines a corresponding equipment type according to the initial three-phase current and the initial three-phase voltage;

[0055] A screening module, used for removing the three-phase current and three-phase voltage that will change during the operation of the circuit breaker / disconnector and the three-phase current and three-phase voltage that are 0 and negative in any period from the initial three-phase current and the initial three-phase voltage, to obtain a final three-phase current and a final three-phase voltage, wherein the final three-phase current is composed of three final phase currents, and the final three-phase voltage is composed of three final phase voltages;

[0056] A calculation module, used for respectively calculating the first unbalance degree, the second unbalance degree, the third unbalance degree and the deviation degree of each device based on the final three-phase current and the final three-phase voltage;

[0057] a determination and display module, for determining whether the final three-phase current and the final three-phase voltage are abnormal based on the set abnormality determination rules according to the imbalance degree 1, the imbalance degree 2, and the imbalance degree 3, and if so, determining the abnormality level of the final three-phase current and the final three-phase voltage and outputting the abnormal final three-phase current and the final three-phase voltage and the time range corresponding to the abnormal final three-phase current and the final three-phase voltage, and then identifying the phases that may have abnormalities according to the deviation degree of the abnormal final three-phase current and the final three-phase voltage;

[0058] The permission configuration module is used to configure user permissions in a differentiated manner;

[0059] The setting module is used to set the current warning threshold, the voltage warning threshold, the first current difference threshold, the first voltage difference threshold, the second current difference threshold, and the second voltage difference threshold.

[0060] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0061] Through the early warning method of the present invention, an early warning can be issued in advance for equipment with abnormalities, reminding relevant professionals to pay more attention and prevent problems before they occur. At the same time, the developed early warning module / system can be used to achieve quasi-real-time monitoring, early warning and information push.

[0062] The present invention can cover three-phase current and voltage imbalance anomalies in different forms as much as possible by judging and implementing five types of warnings, namely, threshold over-limit, recent sudden increase warning, historical average over-limit, long-term continuous growth, and short-term continuous growth. By utilizing the developed warning module / system, quasi-real-time monitoring and warning and warning information push can be achieved, indicating that there may be latent defects in the equipment or local abnormal conditions in the power grid, reminding monitoring, operation and maintenance and repair personnel to pay more attention and review and confirm, taking precautions before they occur, and reducing the occurrence of power grid accidents or reducing economic losses and personal injury losses to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0064] Figure 1 The present invention provides a flow chart of a method for early warning of equipment abnormality based on three-phase current and voltage imbalance analysis. DETAILED DESCRIPTION

[0065] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0066] This embodiment 1 provides a device abnormality warning method based on three-phase current and voltage imbalance analysis, such as Figure 1 As shown, including:

[0067] S1, collecting initial three-phase current and initial three-phase voltage;

[0068] All current and voltage data can be read periodically from the new generation centralized control system, D5000 / OPEN3000 system or any other system that can read current and voltage. The time interval (sampling frequency) for reading data can be as short as seconds and can be appropriately extended to minutes, which can be determined by the user according to the needs.

[0069] S2. Determine the corresponding device type according to the initial three-phase current and the initial three-phase voltage;

[0070] According to the grid topology, monitoring information and other necessary information (including but not limited to equipment inventory information, current and voltage data and equipment or branch mapping information, etc.), determine the equipment type corresponding to the read three-phase current and voltage. The equipment type is mainly divided according to the important equipment contained in the branch where the current is located, such as main transformers, circuit breakers / disconnectors, current transformers, capacitors, reactors, busbars and other equipment types. For branches that include multiple important equipment, multiple equipment types are listed at the same time, and circuit breakers / disconnectors in the branch should not be omitted. In addition, for equipment such as busbars, voltage transformers and lightning arresters that use voltage to judge imbalance at the same time, the equipment type can be identified and divided according to the working principle of the equipment and the voltage it can withstand in actual operation.

[0071] Because the current is measured by the current transformer in the power grid, and the branch current value displayed by the current transformer is often associated with the primary equipment such as the circuit breaker or main transformer in the power grid, it is often possible to determine which branch the measured current flows through through this association and mapping rules, and then determine which type of equipment the current reflects (the current transformer and the current branch to be measured are in series).

[0072] According to the main electrical wiring diagram (topological structure) of the substation, most disconnectors (not all disconnectors) are usually connected in series with circuit breakers and are physically arranged relatively close to each other. The branches they are in have the same current value, which is often associated with the circuit breaker based on the topological relationship. It is easy to ignore that this current value is also the current value of the disconnector. The circuit breaker is the most important equipment in the substation besides the main transformer / transformer, so it is proposed that "the circuit breaker / disconnector in the branch should not be omitted". The specific principle for identifying and dividing the equipment type according to the voltage it withstands is: these devices do not pass the system load current in normal operation, but the two ends of the equipment withstand the system operating voltage, so it is called pressure here. The main pressure-bearing primary equipment in the power system is voltage transformers and lightning arresters.

[0073] S3, removing the three-phase current and three-phase voltage that will change during the operation of the circuit breaker / disconnector and the three-phase current and three-phase voltage that are 0 and negative in any period from the initial three-phase current and the initial three-phase voltage, to obtain a final three-phase current and a final three-phase voltage, wherein the final three-phase current is composed of three final phase currents, and the final three-phase voltage is composed of three final phase voltages;

[0074] The main purpose here is to clear the three-phase current and three-phase voltage that will change during the operation of the circuit breaker / disconnector. For example, when the circuit breaker / disconnector changes position, the three-phase voltage and three-phase current will change significantly.

[0075] Combined with the position change alarm information of the circuit breaker / disconnector and related information such as the operation ticket, determine the switch operation time period of the circuit breaker / disconnector in the substation and the operation time period of the circuit breaker / disconnector in the opposite substation of the line corresponding to the substation line breaker, and filter out the current and voltage data in the above time period. The filtered current and voltage data are not used for the calculation of subsequent indicators and early warning judgment.

[0076] Determine whether all three-phase current and voltage data are 0 or negative. If there is a current value or voltage value of 0, output the prompt "XX device (branch) YY phase current is 0" or "XX device (branch) YY phase voltage is 0"; if there is a negative current or voltage, output the prompt "XX device (branch) YY phase current data error" or "XX device (branch) YY phase voltage data error". The three-phase current data / three-phase voltage data at the corresponding moment when the current / voltage is 0 or negative is also not used for the calculation and early warning judgment of subsequent indicators.

[0077] S4, calculating the first unbalance, the second unbalance, the third unbalance and the deviation of each device based on the final three-phase current and the final three-phase voltage;

[0078] Specifically, the imbalance degree 1, imbalance degree 2, imbalance degree 3 and deviation degree include current imbalance degree 1, current imbalance degree 2, current imbalance degree 3, current deviation degree and voltage imbalance degree 1, voltage imbalance degree 2, voltage imbalance degree 3 and voltage deviation degree.

[0079] For the final three-phase current and final three-phase voltage that meet the conditions, the following four indicators are periodically calculated according to actual needs: imbalance one, imbalance two, imbalance three, and current deviation.

[0080] The specific formula of the current imbalance degree IB1 at the same time is:

[0081] IB1=(maxI i -minI i ) / maxI i ;

[0082] That is, IB1 = (maximum current of three phases - minimum current of three phases) / maximum current of three phases;

[0083] Among them, i∈[A, B, C], maxI i Indicates the maximum phase current among the final three-phase currents, minI i represents the smallest phase current among the final three-phase currents, and maxI i and minI i The final three-phase current, I i represents the i-th phase current in the final three-phase current;

[0084] The specific formula of the current imbalance degree IB2 at the same time is:

[0085]

[0086] That is, IB2 = max (phase current - three-phase average current) / three-phase average current, where max means the maximum value;

[0087] in, It represents the arithmetic mean of the three phase currents in the final three-phase current, that is, the three-phase average current, I i represents the i-th phase current in the final three-phase current, i∈[A, B, C];

[0088] The specific formula of the current imbalance degree IB3 at the same time is:

[0089]

[0090] That is, IB3 = (maximum current of three phases - minimum current of three phases) / average current of three phases;

[0091] The current deviation ID of the final phase current of the i-th phase i The specific formula is:

[0092]

[0093] ID i Indicates the current deviation of the final phase current of the i-th phase, I j represents the j-th phase current in the final three-phase current, j∈[A, B, C] and j≠i;

[0094] That is (the current of this phase - the average current of the other two phases) / the average current of the three phases; taking the deviation of the current of phase A as an example, it is defined as: ID A =[A phase current - (B phase current + C phase current) / 2] / average value of three-phase current * 100%. The definition of B and C phase current deviation is similar.

[0095] The specific formula of the voltage imbalance degree VB1 at the same time is:

[0096] VB1=(maxV i -minV i ) / maxV i ;

[0097] Among them, i∈[A, B, C], maxV i Indicates the maximum phase voltage among the final three-phase voltages, minV i represents the minimum phase voltage among the final three-phase voltages, and maxVI i and minV i The final three-phase voltage, V i represents the i-th phase voltage in the final three-phase voltage;

[0098] The specific formula of the voltage imbalance degree VB2 at the same time is:

[0099]

[0100] in, It represents the arithmetic mean of the three phase voltages in the final three-phase voltage, that is, the three-phase average voltage, V i represents the i-th phase voltage in the final three-phase voltage, i∈[A, B, C];

[0101] The specific formula of the voltage imbalance degree IB3 at the same time is:

[0102]

[0103] The voltage deviation VD of the final phase voltage of the i-th phase i The specific formula is:

[0104]

[0105] Among them, VD i Represents the voltage deviation of the final phase voltage of the i-th phase, V j represents the i-th phase voltage in the final three-phase voltage, j∈[A, B, C] and j≠i.

[0106] That is (the voltage of the phase - the average voltage of the other two phases) / the average voltage of the three phases; taking the deviation of the voltage of phase A as an example, it is defined as: ID A =[A phase voltage - (B phase voltage + C phase voltage) / 2] / average value of three-phase voltage * 100%. The definition of B and C phase voltage deviation is similar.

[0107] The calculation of all the above indicators adopts the values ​​at the same time. Through the above design, when the current of one phase is larger or smaller than that of the other two phases, the abnormality can be quickly found through the numerical difference of the three-phase unbalance value.

[0108] S5. Determine whether the final three-phase current and / or final three-phase voltage are abnormal based on the set abnormal judgment rules according to the imbalance degree 1, imbalance degree 2, and imbalance degree 3. If so, determine the abnormal level of the final three-phase current and / or final three-phase voltage and directionally output the abnormal final three-phase current and / or final three-phase voltage and the time range corresponding to the abnormal final three-phase current and / or final three-phase voltage. Then, identify the phase that may have the abnormality according to the deviation degree of the abnormal final three-phase current and / or final three-phase voltage, and then return to S1. Otherwise, directly return to S1 to continue monitoring the equipment.

[0109] According to the imbalance degree 1, imbalance degree 2, imbalance degree 3 and deviation degree of the three-phase current and voltage of the branch, it is judged whether the corresponding equipment has abnormality, so as to issue an early warning. The abnormality here refers to the existence of defects, hidden dangers, failures or any other deviations from the normal state of the equipment.

[0110] Large differences in the imbalance of three-phase current and voltage often indicate abnormal local operating conditions of the system or defects / hidden dangers / faults in the equipment itself. The imbalance index is a relatively rough judgment indicator. There is no specific correspondence between the specific defect / fault type and the imbalance characteristics. It can only be used as a preliminary warning.

[0111] If any of the following items are met, a warning of the corresponding type will be issued, and the warning level is level 2; if any two or more of the following items are met, a warning of the corresponding type will be issued together, and the warning level is level 1. At the same time, the three-phase current / voltage unbalance time (range) that meets the conditions is output. The warning level measures the severity of the abnormal characteristics of the three-phase current and voltage unbalance. Level 1 means that it is more serious than level 2 and should be paid more attention.

[0112] The abnormality judgment rule includes a threshold over-limit warning type judgment rule, which is specifically:

[0113] If any of the current imbalance degree 1 IB1, the current imbalance degree 2 IB2, and the current imbalance degree 3 IB3 exceeds the current warning threshold, the final three-phase current is determined to be abnormal, and a three-phase current imbalance threshold exceeding warning is issued;

[0114] If any one of the voltage imbalance degree 1 VB1, the voltage imbalance degree 2 VB2, and the voltage imbalance degree 3 VB3 exceeds the voltage warning threshold, the final three-phase voltage is determined to be abnormal, and a three-phase voltage imbalance threshold exceeding warning is issued.

[0115] That is, the preset judgment rule is the threshold over-limit warning type. If the current value of the imbalance exceeds the warning threshold Y0 (if the current imbalance is determined, the warning threshold is the current warning threshold; if the voltage imbalance is determined, the warning threshold is the voltage warning threshold), then a "threshold over-limit" warning is issued. The imbalance here refers to any one of imbalance 1, imbalance 2, and imbalance 3 that meets the over-limit, the same below. Y0 is a percentage and can be configured according to the equipment type, power grid operation status and historical values: if the purpose is to identify abnormal power grid operation conditions / equipment failures, it can be set to 80% or above; if the purpose is to discover possible main equipment abnormalities / latent defects in advance, it can be set to 30% or even lower, and differentiated configurations are performed according to equipment type, power grid operation status and historical load conditions. The warning thresholds Y0 of imbalance 1, imbalance 2, and imbalance 3 are not necessarily the same, and can be configured differently according to actual conditions.

[0116] The abnormality judgment rules include the recent sudden increase warning type judgment rules, which are specifically:

[0117] If the relative difference between the cumulative average value of any one of the current imbalance degree IB1, the current imbalance degree IB2, and the current imbalance degree IB3 from the first previous moment to the current moment and the cumulative average value of the corresponding current imbalance degree from the second previous moment to the first previous moment is not less than the first current difference threshold, let the relative difference be the first current relative difference, and any one of the current imbalance degree IB1, the current imbalance degree IB2, and the current imbalance degree IB3 from the first previous moment to the current moment is greater than the cumulative average value of the corresponding current imbalance degree from the second previous moment to the first previous moment, then it is determined that the final three-phase current Abnormal, issue a warning of a recent sudden increase in three-phase current imbalance, wherein the first previous moment is before the current moment, the second previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, the absolute value of the time difference between the second previous moment and the first previous moment is greater than or equal to 24 hours and less than or equal to 72 hours, and the first current relative difference = (the cumulative average value of the current imbalance from the first previous moment to the current moment - the cumulative average value of the current imbalance from the second previous moment to the first previous moment) / the cumulative average value of the current imbalance from the second previous moment to the first previous moment * 100%;

[0118] If the relative difference between the cumulative average value of any one of the voltage imbalance degree VB1, the voltage imbalance degree VB2, and the voltage imbalance degree VB3 from the first previous moment to the current moment and the cumulative average value of the corresponding voltage imbalance degree from the second previous moment to the first previous moment is not less than the first voltage difference threshold, let the relative difference be the first voltage relative difference, and any one of the voltage imbalance degree VB1, the voltage imbalance degree VB2, and the voltage imbalance degree VB3 from the first previous moment to the current moment is greater than the cumulative average value of the corresponding voltage imbalance degree from the second previous moment to the first previous moment, then it is determined that the final three-phase voltage Abnormal, issue a warning of a recent sudden increase in three-phase voltage imbalance, wherein the first previous moment is before the current moment, the second previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, the absolute value of the time difference between the second previous moment and the first previous moment is greater than or equal to 24 hours and less than or equal to 72 hours, and the first voltage relative difference = (the cumulative average value of the voltage imbalance from the first previous moment to the current moment - the cumulative average value of the voltage imbalance from the second previous moment to the first previous moment) / the cumulative average value of the voltage imbalance from the second previous moment to the first previous moment * 100%.

[0119] Here, the first previous time may be 0:00 of the date on which the current time is located, and the second previous time may be 0:00 of the day before the date on which the current time is located.

[0120] In other words, the final judgment rule of the recent sudden increase warning type of the three-phase current is as follows:

[0121] If the relative difference C1 between the cumulative average value of the current imbalance (one, two or three) at this moment of the day (i.e., the average value of the current imbalance within the time range from the current moment to 0:00 of the day) and the daily average value of the current imbalance (one, two or three) of the previous day is greater than or equal to Y1 (the first current difference threshold), and the current imbalance value at any moment of the day is greater than the daily average value of the current imbalance of the previous day, then a "recent sudden increase" warning is issued. Among them, C1 = (the cumulative average value of the current imbalance at this moment of the day - the daily average value of the current imbalance of the previous day) / the daily average value of the current imbalance of the previous day * 100%, percentage; Y1 can be 15% or more, and can be adjusted according to the equipment type, branch conditions, imbalance index type and application experience, and can also be set in sections according to the range of the cumulative average value of the current imbalance at this moment. The mean value refers to the arithmetic mean value of the three-phase current imbalance within a specific time range that meets the conditions. The same is true for the three-phase voltage data, which will not be repeated here.

[0122] The main purpose of segmentation setting is to control the accuracy of judgment and minimize misjudgment. For example, when the current cumulative average value of imbalance is 5% or less, Y1 can be set to 50% or more, because when the cumulative average value of imbalance is in a smaller value range, the fluctuation of imbalance is greatly affected by the fluctuation of system voltage and current values. It is necessary to allow the imbalance value to have a larger change compared with historical data to reduce the possibility of misjudgment; for example, when the current cumulative average value of imbalance is 10% or more, Y1 can be set to 15% or more. The above is just an example, but the value of Y1 should also be determined comprehensively based on the equipment type, branch conditions, imbalance index type and application experience, where the imbalance index type refers to whether imbalance one, imbalance two or imbalance three is used.

[0123] The abnormal judgment rule includes the historical mean over-limit warning type judgment rule, which is specifically:

[0124] If the relative difference between the cumulative average value of any one of the current imbalance degree IB1, the current imbalance degree IB2, and the current imbalance degree IB3 from the first previous moment to the current moment and the corresponding cumulative average value of the current imbalance degree from the third previous moment to the current moment is greater than the second current difference threshold, let the relative difference be the second current relative difference, wherein the first previous moment is before the current moment, the third previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, and the absolute value of the time difference between the third previous moment and the current moment ranges from 180 to 366 days, then it is determined that the final three-phase current is abnormal, and an alarm of the historical average value exceeding the limit of the three-phase current imbalance is issued, and the second current relative difference = (the cumulative average value of the voltage imbalance from the first previous moment to the current moment - the cumulative average value of the voltage imbalance from the third previous moment to the current moment) / the cumulative average value of the voltage imbalance from the third previous moment to the current moment * 100%;

[0125] If the relative difference between the cumulative average value of any one of the voltage imbalance degree VB1, the voltage imbalance degree VB2, and the voltage imbalance degree VB3 from the first previous moment to the current moment and the cumulative average value of the corresponding voltage imbalance degree from the third previous moment to the current moment is greater than the second voltage difference threshold, let the relative difference be the second voltage relative difference, wherein the first previous moment is before the current moment, the third previous moment is before the first previous moment, and the absolute value of the time difference from the first previous moment to the current moment is less than or equal to 24 hours, and the absolute value of the time difference from the third previous moment to the current moment ranges from 180 to 366 days, then it is determined that the final three-phase voltage is abnormal, and an alarm of the historical average value exceeding the limit of the three-phase voltage imbalance is issued, and the second voltage relative difference=(the cumulative average value of the voltage imbalance from the first previous moment to the current moment-the cumulative average value of the voltage imbalance from the third previous moment to the current moment) / the cumulative average value of the voltage imbalance from the third previous moment to the current moment*100%.

[0126] Taking three-phase current as an example, the first previous moment is 0:00 of the date of the current moment, and the third previous moment is the past year or half a year, taking the third previous moment as the past year as an example.

[0127] That is, the judgment rule of the historical mean value exceeding the limit warning type is: if the relative difference C2 between the cumulative average value of the current unbalance degree (one or two or three) at that moment of the day and the cumulative average value of the current unbalance degree (one or two or three) in the past year or half a year is greater than Y2 (the second current difference threshold) or more, then a "historical mean value exceeding the limit" warning is issued. Among them, C2 = (the cumulative average value at that moment of the day - the cumulative average value of the unbalance degree in the past year or half a year) / the cumulative average value of the unbalance degree in the past year or half a year * 100%, percentage; Y2 can be 10% or more, and can be adjusted according to the equipment type, branch conditions and application experience, and can also be set in sections according to the range of the cumulative average value of the current unbalance degree at that moment.

[0128] The abnormality judgment rule includes a long-term continuous growth warning type judgment rule, which is specifically:

[0129] If the daily average value of any one of the current imbalance degrees IB1, IB2, and IB3 shows a continuous growth trend in the M days from the current moment, the final three-phase current is determined to be abnormal, and a warning of long-term continuous growth of the three-phase current imbalance is issued, where M is a positive integer;

[0130] If the daily average value of any one of the voltage imbalance degrees VB1, VB2 and VB3 shows a continuous growth trend in the M days near the current moment, the final three-phase voltage is determined to be abnormal, and a warning of long-term continuous growth of the three-phase voltage imbalance is issued.

[0131] That is, the judgment rules for the long-term continuous growth warning type are:

[0132] Taking the imbalance degree IB1 as an example, let the daily average values ​​of the imbalance degree in the past M days (from the past to the most recent) be IB11, IB12, IB13, ..., IB1M, and M be an integer in the range of 3-7. If the daily average value of the imbalance degree 1 in the past M days shows a continuous growth trend, that is, it satisfies I11<I12<……<I1M, then a "continuous growth in the past M days" warning is issued. Taking M=5 as an example, if the daily average value of the imbalance degree 1 in the past 5 days shows a continuous growth trend, that is, it satisfies I11<I12<I13<I14<I15, then a "continuous growth in the past 5 days" warning is issued.

[0133] The abnormality judgment rule includes a short-term continuous growth warning type judgment rule, which is specifically:

[0134] If the average value of the current unbalance degrees in any one of the current unbalance degree one IB1, current unbalance degree two IB2, and current unbalance degree three IB3 in R time - length intervals with a time interval of N minutes and close to the current moment by P hours shows a continuous increasing trend along the time axis, and the average value of the current unbalance degree in the time - length interval closest to the current moment is at least 1.5 times the average value of the current unbalance degree in the time - length interval farthest from the current moment, then it is determined that the final three - phase current is abnormal, and a short - term continuous growth warning of three - phase current unbalance is issued. P, N, and R are positive integers;

[0135] If the average value of the voltage unbalance degrees in any one of the voltage unbalance degree one VB1, voltage unbalance degree two VB2, and voltage unbalance degree three VB3 in R time - length intervals with a time interval of N minutes and close to the current moment by P hours shows a continuous increasing trend along the time axis, and the average value of the voltage unbalance degree in the time - length interval closest to the current moment is at least 1.5 times the average value of the voltage unbalance degree in the time - length interval farthest from the current moment, then it is determined that the final three - phase voltage is abnormal, and a short - term continuous growth warning of three - phase voltage unbalance is issued. Here, P * 60 = N * R. P, N, and R are positive integers.

[0136] That is, the judgment rule for the short - term continuous growth warning type is:

[0137] With a time interval of N minutes, the time range of the nearest P hours from the current moment is divided into R equal - length intervals. Let the mean unbalance degrees of each equal - length interval be IB11, IB12, ……, IB1R in sequence. If the average unbalance degrees corresponding to each equal - length interval satisfy a continuous increasing trend (i.e., IB11 < IB12 < …… < IB1R) and the mean unbalance degree of the last time - length interval is greater than or equal to Y3 more than the mean unbalance degree of the earliest time - length interval (i.e., (IB1R - IB11) / IB11 * 100% ≥ Y3), then a warning of "continuous growth within P hours of the current day" is issued. Among them, it is recommended that N take values from 30 to 60 minutes, P take values from 6 to 12 hours, and Y3 take 100% and above, that is, the mean unbalance degree of the last time - length interval is 2 times or more the mean unbalance degree of the earliest time - length interval.

[0138] In S5, the specific process of identifying the phases that may be abnormal according to the deviation degrees of the abnormal final three - phase current and / or final three - phase voltage is as follows:

[0139] Compare the three deviations of the abnormal final three-phase current and / or final three-phase voltage, and take the current and / or voltage of the phase with the largest absolute value of the deviation as the abnormal phase. If the deviation is a negative value, the current and / or voltage of the abnormal phase is a current and / or voltage that is too small. If the deviation is a positive value, the current and / or voltage of the abnormal phase is a current and / or voltage that is too large.

[0140] When any one or more of the warning conditions in the above judgment rules are met, the phase that may have an abnormality is identified according to the deviation of the three-phase current / voltage (that is, quickly determine whether the abnormality is in phase A, phase B or phase C). The judgment method is as follows: Compare the three-phase deviation ID A 、ID B 、ID C The absolute value of the current is determined by the phase with the largest absolute value, and the phase with the largest absolute value is the phase with abnormally large / small current of the three-phase. The relative size relationship between the current / voltage of the phase and other phases can be determined based on the positive or negative deviation.

[0141] Embodiment 2 further discloses an equipment abnormality warning system based on three-phase current and voltage imbalance analysis, including:

[0142] A collection module, used for collecting initial three-phase current and initial three-phase voltage;

[0143] An equipment classification module, which determines the equipment type according to the initial three-phase current and the initial three-phase voltage;

[0144] A screening module, used for removing the three-phase current and three-phase voltage that will change during the operation of the circuit breaker / disconnector and the three-phase current and three-phase voltage that are 0 and negative in any period from the initial three-phase current and the initial three-phase voltage, to obtain a final three-phase current and a final three-phase voltage, wherein the final three-phase current is composed of three final phase currents, and the final three-phase voltage is composed of three final phase voltages;

[0145] A calculation module, used for respectively calculating the first unbalance degree, the second unbalance degree, the third unbalance degree and the deviation degree of each device based on the final three-phase current and the final three-phase voltage;

[0146] a determination and display module, for determining whether the final three-phase current and the final three-phase voltage are abnormal based on the set abnormality determination rules according to the imbalance degree 1, the imbalance degree 2, and the imbalance degree 3, and if so, determining the abnormality level of the final three-phase current and the final three-phase voltage and outputting the abnormal final three-phase current and the final three-phase voltage and the time range corresponding to the abnormal final three-phase current and the final three-phase voltage, and then identifying the phases that may have abnormalities according to the deviation degree of the abnormal final three-phase current and the final three-phase voltage;

[0147] The permission configuration module is used to configure user permissions in a differentiated manner;

[0148] The setting module is used to set the current warning threshold, the voltage warning threshold, the first current difference threshold, the first voltage difference threshold, the second current difference threshold, and the second voltage difference threshold.

[0149] According to the above warning algorithm, a corresponding warning system is developed. The important features of the system are:

[0150] Through the acquisition module, data can be retrieved to calculate the historical data of the same equipment in the past 1 year / 6 months / 3 months / 1 month and display it in a curve. Through the judgment and display module, the calculation results can be displayed in real time, and the user unit can choose any one or more of the imbalance degree 1, imbalance degree 2, and imbalance degree 3.

[0151] For the data displayed in the judgment display module, the user unit can filter the calculation / warning results according to the unit, equipment type, voltage level, date range and other attributes, and can display and filter the warning results according to the equipment type.

[0152] The setting of the threshold has a certain degree of autonomy, depending on the type of warning equipment and the specific purpose of the user unit. The user unit can personalize the warning threshold through the setting module.

[0153] The warning results should include the current / voltage three-phase unbalanced time (range) that meets the conditions. If a single point meets the same warning type multiple times in the same day or continuously meets the same warning type in a period of time, they are all merged and output as one record, and different warning types are not merged. The unbalance column gives all unsatisfied values, and the time (range) column gives the corresponding time (range).

[0154] User permissions can be configured differently: each grassroots user unit only has viewing permissions within the scope of all its substations, and the core account has the permissions for full-range query and screening and independent configuration, screening and push.

[0155] At the same time, early warning information can be pushed in a targeted manner.

[0156] Next, the method of the present invention is further demonstrated through specific cases.

[0157] Case 1:

[0158] The system found that the daily average values ​​of the three-phase current imbalance 1 and imbalance 2 of the 5023 circuit breaker of a 500kV substation showed a gradual increase trend in the past 4 days (May 15, 2024-May 18, 2024) (see Table 1), and it was determined to be a long-term continuous growth warning type. Therefore, a "continuous growth in the past 4 days" warning was issued to remind monitoring, operation and maintenance personnel that there may be equipment abnormalities in the branch where the 5023 circuit breaker is located. At the same time, it was calculated that the absolute value of the deviation degree ID_C of phase C was the largest, and it was initially determined that the abnormal phase might be phase C.

[0159] Table 15023 Daily average value of three-phase current unbalance of circuit breaker

[0160] date May 15 May 16 May 17 May 18 Imbalance 1 18.4678％ 20.3710％ 21.6799％ 22.7727％ Imbalance 2 8.7151％ 9.4898％ 10.4346％ 11.1942％

[0161] Shortly after the warning was issued, the No. 1 and No. 2 protections of a 500 kV line of the 500 kV substation were activated, phase C was selected, and the 5022 and 5023 circuit breakers of the line tripped, and the reclosing was unsuccessful. On-site inspection found that the shielding cover at the connection between the movable contact of the 50231 disconnector gas chamber and the pot-type insulator inside the C phase was obviously burned. Disassembly confirmed that the C phase gas chamber of the 50231 disconnector and the C phase I mother-side pot-type insulator of the 5023 circuit breaker had breakdown discharge. The accident and disassembly results verified the warning results.

[0162] Case 2:

[0163] The cumulative average values ​​of the three-phase unbalance 1 and three-phase unbalance 2 of the three-phase current of the 5033 circuit breaker of a 500kV substation within the 10-hour range from 9:00 to 19:00 on May 15 were 16.6423% and 7.7263% respectively (the range from 0:00 to 9:00 on the 15th corresponds to the operation or power outage period, and the current data does not meet the conditions and is not included in the statistical scope), which are 23.3% and 10.3% higher than the daily average values ​​of the three-phase unbalance on May 14, respectively, and greater than the set threshold of 10%. In addition, the three-phase unbalance at any time within the 10-hour range from 9:00 to 19:00 on May 15 is greater than the daily average value of the three-phase unbalance on May 14, meeting the recent sudden increase warning type, and a "recent sudden increase warning" prompt is issued. For the three-phase deviation ID A _A. ID -B 、ID_ C The absolute value of ID_B was compared and it was found that the absolute value of ID_B was larger. It was initially determined that the abnormal phase might be phase B. Shortly after the warning was issued, at 19:02 on May 15, the phase B of the current transformer of the 5033 circuit breaker of the station failed, causing the 500kV II bus and a 500kV line to trip, verifying the previous warning results.

[0164] The specific implementation methods 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 implementation method 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 device abnormality early warning method based on three-phase current and voltage imbalance, characterized in that: include: S1, collecting initial three-phase current and initial three-phase voltage; S2. Determine the device type according to the initial three-phase current and the initial three-phase voltage; S3, removing the three-phase current and three-phase voltage that will change during the operation of the circuit breaker / disconnector and the three-phase current and three-phase voltage that are 0 and negative in any period from the initial three-phase current and the initial three-phase voltage, to obtain a final three-phase current and a final three-phase voltage, wherein the final three-phase current is composed of three final phase currents, and the final three-phase voltage is composed of three final phase voltages; S4, calculating the first unbalance, the second unbalance, the third unbalance and the deviation of each device based on the final three-phase current and the final three-phase voltage; S5. Determine whether there is an abnormality based on the set abnormality judgment rules according to the imbalance degree 1, imbalance degree 2, and imbalance degree 3. If so, determine the abnormality level and directionally output the abnormality and the time range corresponding to the abnormal final three-phase current and / or final three-phase voltage. Then, identify the phase that may have the abnormality according to the deviation of the abnormal final three-phase current and / or final three-phase voltage, and then return to S1. Otherwise, directly return to S1 to continue monitoring the equipment.

2. The device abnormality early warning method based on three-phase current and voltage imbalance according to claim 1 is characterized in that: The imbalance degree 1, imbalance degree 2, imbalance degree 3 and deviation degree include current imbalance degree 1, current imbalance degree 2, current imbalance degree 3, current deviation degree and voltage imbalance degree 1, voltage imbalance degree 2, voltage imbalance degree 3 and voltage deviation degree.

3. The device abnormality early warning method based on three-phase current and voltage imbalance according to claim 2 is characterized in that: The specific formula of the current imbalance degree IB1 at the same time is: IB1=(maxI i -mini i ) / maxi i ; Among them, i∈[A,B,C], maxI i Indicates the maximum phase current among the final three-phase currents, minI i represents the smallest phase current among the final three-phase currents, and maxI i and minI i The final three-phase current, I i represents the i-th phase current in the final three-phase current; The specific formula of the current imbalance degree IB2 at the same time is: in, It represents the arithmetic mean of the three phase currents in the final three-phase current, that is, the three-phase average current, I i represents the i-th phase current in the final three-phase current, i∈[A,B,C]; The specific formula of the current imbalance degree IB3 at the same time is: The current deviation ID of the final phase current of the i-th phase i The specific formula is: ID i represents the current deviation of the final phase current of the i-th phase, j∈[A,B,C] and j≠i; The specific formula of the voltage imbalance degree VB1 at the same time is: VB1=(maxV i -minV i ) / maxV i ; Among them, i∈[A,B,C], maxV i Indicates the maximum phase voltage among the final three-phase voltages, minV i represents the minimum phase voltage among the final three-phase voltages, and maxV i and minV i The final three-phase voltage, V i Represents the i-th phase voltage in the final three-phase voltage; The specific formula of the voltage imbalance degree VB2 at the same time is: in, It represents the arithmetic mean of the three phase voltages in the final three-phase voltage, that is, the three-phase average voltage, V i represents the i-th phase voltage in the final three-phase voltage, i∈[A,B,C]; The specific formula of the voltage imbalance degree VB3 at the same time is: The voltage deviation VD of the final phase voltage of the i-th phase i The specific formula is: Among them, VD i Represents the voltage deviation degree of the final phase voltage of the i-th phase, j∈[A,B,C] and j≠i.

4. The device abnormality early warning method based on three-phase current and voltage imbalance according to claim 3 is characterized in that: The abnormality judgment rule includes a threshold over-limit warning type judgment rule, which is specifically: If any of the current imbalance degree 1 IB1, the current imbalance degree 2 IB2, and the current imbalance degree 3 IB3 exceeds the current warning threshold, the final three-phase current is determined to be abnormal, and a three-phase current imbalance threshold exceeding warning is issued; If any one of the voltage imbalance degree 1 VB1, the voltage imbalance degree 2 VB2, and the voltage imbalance degree 3 VB3 exceeds the voltage warning threshold, the final three-phase voltage is determined to be abnormal, and a three-phase voltage imbalance threshold exceeding warning is issued.

5. The device abnormality early warning method based on three-phase current and voltage imbalance according to claim 4 is characterized in that: The abnormality judgment rules include the recent sudden increase warning type judgment rules, which are specifically: If the relative difference between the cumulative average value of any one of the current imbalance degree IB1, the current imbalance degree IB2, and the current imbalance degree IB3 from the first previous moment to the current moment and the cumulative average value of the corresponding current imbalance degree from the second previous moment to the first previous moment is not less than the first current difference threshold, let the relative difference be the first current relative difference, and any one of the current imbalance degree IB1, the current imbalance degree IB2, and the current imbalance degree IB3 from the first previous moment to the current moment is greater than the cumulative average value of the corresponding current imbalance degree from the second previous moment to the first previous moment, then it is determined that the final three-phase current Abnormal, issue a warning of a recent sudden increase in three-phase current imbalance, wherein the first previous moment is before the current moment, the second previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, the absolute value of the time difference between the second previous moment and the first previous moment is greater than or equal to 24 hours and less than or equal to 72 hours, and the first current relative difference = (the cumulative average value of the current imbalance from the first previous moment to the current moment - the cumulative average value of the current imbalance from the second previous moment to the first previous moment) / the cumulative average value of the current imbalance from the second previous moment to the first previous moment * 100%; If the relative difference between the cumulative average value of any one of the voltage imbalance degree VB1, the voltage imbalance degree VB2, and the voltage imbalance degree VB3 from the first previous moment to the current moment and the cumulative average value of the corresponding voltage imbalance degree from the second previous moment to the first previous moment is not less than the first voltage difference threshold, let the relative difference be the first voltage relative difference, and any one of the voltage imbalance degree VB1, the voltage imbalance degree VB2, and the voltage imbalance degree VB3 from the first previous moment to the current moment is greater than the cumulative average value of the corresponding voltage imbalance degree from the second previous moment to the first previous moment, then it is determined that the final three-phase voltage Abnormal, issue a warning of a recent sudden increase in three-phase voltage imbalance, wherein the first previous moment is before the current moment, the second previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, the absolute value of the time difference between the second previous moment and the first previous moment is greater than or equal to 24 hours and less than or equal to 72 hours, and the first voltage relative difference = (the cumulative average value of the voltage imbalance from the first previous moment to the current moment - the cumulative average value of the voltage imbalance from the second previous moment to the first previous moment) / the cumulative average value of the voltage imbalance from the second previous moment to the first previous moment * 100%.

6. The device abnormality early warning method based on three-phase current and voltage imbalance according to claim 4 is characterized in that: The abnormal judgment rule includes the historical mean over-limit warning type judgment rule, which is specifically: If the relative difference between the cumulative average value of any one of the current imbalance degree IB1, the current imbalance degree IB2, and the current imbalance degree IB3 from the first previous moment to the current moment and the corresponding cumulative average value of the current imbalance degree from the third previous moment to the current moment is not less than the second current difference threshold, let the relative difference be the second current relative difference, wherein the first previous moment is before the current moment, the third previous moment is before the first previous moment, and the absolute value of the time difference between the first previous moment and the current moment is less than or equal to 24 hours, and the absolute value of the time difference between the third previous moment and the current moment ranges from 180 to 366 days, then it is determined that the final three-phase current is abnormal, and an alarm of the historical average value exceeding the limit of the three-phase current imbalance is issued, and the second current relative difference = (the cumulative average value of the voltage imbalance from the first previous moment to the current moment - the cumulative average value of the voltage imbalance from the third previous moment to the current moment) / the cumulative average value of the voltage imbalance from the third previous moment to the current moment * 100%; If the relative difference between the cumulative average value of any one of the voltage imbalance degree VB1, the voltage imbalance degree VB2, and the voltage imbalance degree VB3 from the first previous moment to the current moment and the corresponding cumulative average value of the voltage imbalance degree from the third previous moment to the current moment is not less than the second voltage difference threshold, let the relative difference be the second voltage relative difference, wherein the first previous moment is before the current moment, the third previous moment is before the first previous moment, and the absolute value of the time difference from the first previous moment to the current moment is less than or equal to 24 hours, and the absolute value of the time difference between the third previous moment and the current moment ranges from 180 to 366 days, then it is determined that the final three-phase voltage is abnormal, and an alarm of the historical average value exceeding the limit of the three-phase voltage imbalance is issued, and the second voltage relative difference=(the cumulative average value of the voltage imbalance degree from the first previous moment to the current moment-the cumulative average value of the voltage imbalance degree from the third previous moment to the current moment) / the cumulative average value of the voltage imbalance degree from the third previous moment to the current moment*100%.

7. The device abnormality early warning method based on three-phase current and voltage imbalance according to claim 1 is characterized in that: The abnormality judgment rule includes a long-term continuous growth warning type judgment rule, which is specifically: If the daily average value of any one of the current imbalance degrees IB1, IB2, and IB3 shows a continuous growth trend in the M days from the current moment, the final three-phase current is determined to be abnormal, and a warning of long-term continuous growth of the three-phase current imbalance is issued, where M is a positive integer; If the daily average value of any one of the voltage imbalance degrees VB1, VB2 and VB3 shows a continuous growth trend in the M days near the current moment, the final three-phase voltage is determined to be abnormal, and a warning of long-term continuous growth of the three-phase voltage imbalance is issued.

8. The device abnormality early warning method based on three-phase current and voltage imbalance according to claim 1 is characterized in that: The abnormality judgment rule includes a short-term continuous growth warning type judgment rule, which is specifically: If the average value of any one of the current imbalance degrees IB1, IB2, and IB3 in the R time intervals with a time interval of N minutes and P hours away from the current moment shows a continuous growth trend along the time axis, and the average value of the current imbalance degree in the time interval closest to the current moment is at least 1.5 times the average value of the current imbalance degree in the time interval farthest from the current moment, then it is determined that the final three-phase current is abnormal, and a short-term continuous growth warning of the three-phase current imbalance is issued, and P, N, and R are positive integers; If the average value of the voltage imbalance of any one of the voltage imbalance VB1, voltage imbalance VB2 and voltage imbalance VB3 in R time intervals with a time interval of N minutes and nearly P hours from the current moment shows a continuous increasing trend along the time axis, and the average value of the voltage imbalance in the time interval closest to the current moment is at least 1.5 times the average value of the voltage imbalance in the time interval farthest from the current moment, then the final three-phase voltage is determined to be abnormal, and a short-term continuous increase warning of the three-phase voltage imbalance is issued, and P, N, and R are positive integers.

9. The device abnormality early warning method based on three-phase current and voltage imbalance according to claim 1 is characterized in that: In S5, the specific process of identifying the phases that may have abnormalities according to the deviation between the abnormal final three-phase current and the final three-phase voltage is as follows: Compare the three deviations of the abnormal final three-phase current and / or final three-phase voltage, and take the current and / or voltage of the phase with the largest absolute value of the deviation as the abnormal phase. If the deviation is a negative value, the current and / or voltage of the abnormal phase is a current and / or voltage that is too small. If the deviation is a positive value, the current and / or voltage of the abnormal phase is a current and / or voltage that is too large.

10. An equipment abnormality warning system based on three-phase current and voltage imbalance, characterized in that: include: A collection module, used for collecting initial three-phase current and initial three-phase voltage; An equipment classification module determines a corresponding equipment type according to the initial three-phase current and the initial three-phase voltage; A screening module, used for removing the three-phase current and three-phase voltage that will change during the operation of the circuit breaker / disconnector and the three-phase current and three-phase voltage that are 0 and negative in any period from the initial three-phase current and the initial three-phase voltage, to obtain a final three-phase current and a final three-phase voltage, wherein the final three-phase current is composed of three final phase currents, and the final three-phase voltage is composed of three final phase voltages; A calculation module, used for respectively calculating the first unbalance degree, the second unbalance degree, the third unbalance degree and the deviation degree of each device based on the final three-phase current and the final three-phase voltage; a determination and display module, for determining whether the final three-phase current and the final three-phase voltage are abnormal based on the set abnormality determination rules according to the imbalance degree 1, the imbalance degree 2, and the imbalance degree 3, and if so, determining the abnormality level of the final three-phase current and the final three-phase voltage and outputting the abnormal final three-phase current and the final three-phase voltage and the time range corresponding to the abnormal final three-phase current and the final three-phase voltage, and then identifying the phases that may have abnormalities according to the deviation degree of the abnormal final three-phase current and the final three-phase voltage; The permission configuration module is used to configure the user's permissions differently; The setting module is used to set the current warning threshold, the voltage warning threshold, the first current difference threshold, the first voltage difference threshold, the second current difference threshold, and the second voltage difference threshold.

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