CN114935697A - Three-phase load unbalance identification method, system, equipment and medium - Google Patents
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Abstract
The invention discloses a method, a system, equipment and a medium for identifying three-phase load unbalance. And then judging whether the three-phase load unbalance activity is greater than or equal to a preset activity threshold, and if the three-phase load unbalance activity is greater than or equal to the preset activity threshold, determining that the three-phase load unbalance type to which the distribution transformer to be detected belongs is continuous three-phase load unbalance. If the three-phase unbalanced load activity is smaller than a preset activity threshold value, determining the three-phase unbalanced load type to which the distribution transformer to be detected belongs according to three-phase daily load historical data and a preset outlier threshold value, and accurately identifying the three-phase unbalanced load type to which the distribution transformer belongs by setting two judgment indexes of the activity threshold value and the outlier threshold value so as to avoid misjudgment.
Description
Technical Field
The invention relates to the technical field of three-phase load unbalance recognition, in particular to a method, a system, equipment and a medium for recognizing three-phase load unbalance.
Background
Most low-voltage distribution systems in China adopt a three-phase four-wire system wiring mode, and the problem of single-phase load imbalance is easily caused by the three-phase four-wire system wiring mode, so that the load on the output side of a distribution transformer is in a three-phase imbalance state. The three-phase unbalanced load of the distribution transformer can reduce the output of the distribution transformer, lower the supply voltage of a user line and increase the line loss, so that the three-phase unbalanced load condition of the distribution transformer needs to be detected.
Currently, a load control terminal connected to a distribution transformer collects a set of three-phase current data every 15 minutes, transmits the three-phase current data to a master station system, and stores the three-phase current data in a database. And calculating a real-time value of the three-phase balance degree by adopting the latest three-phase current data in the main station system, and judging whether the three-phase load of the distribution transformer is unbalanced or not by judging whether the real-time value exceeds 15%.
However, the method only gives the judgment result of yes or no, and does not consider that some random single-phase loads cause short-time or instantaneous three-phase load imbalance, which is allowed in theory and engineering practice, but the method classifies the corresponding distribution transformer as the category of load three-phase imbalance, so that the judgment result is low in accuracy.
Disclosure of Invention
The invention provides a method, a system, equipment and a medium for identifying three-phase load unbalance, which solve the technical problems that the existing three-phase load unbalance identification method only gives a judgment result of yes or no, and does not consider that some random single-phase loads can cause short-time or instantaneous three-phase load unbalance, which is allowed in theory and engineering practice, but the method can list corresponding distribution transformers as the category of load three-phase unbalance, so that the accuracy of the judgment result is low.
The invention provides a three-phase load unbalance identification method, which comprises the following steps:
when three-phase daily load historical data of a distribution transformer to be detected are received, determining three-phase load unbalance activity corresponding to the distribution transformer to be detected according to the three-phase daily load historical data;
judging whether the three-phase load unbalance activity is greater than or equal to a preset activity threshold value or not;
if so, determining that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is continuous three-phase load imbalance;
and if not, determining the three-phase load unbalance type of the distribution transformer to be detected according to the three-phase daily load historical data and a preset outlier threshold.
Optionally, the method further comprises:
and when the three-phase load unbalance type to which the distribution transformer to be detected belongs is determined, starting an alarm signal corresponding to the three-phase load unbalance type.
Optionally, when three-phase daily load historical data of a distribution transformer to be detected is received, the step of determining the three-phase load imbalance activity corresponding to the distribution transformer to be detected according to the three-phase daily load historical data includes:
when three-phase daily load historical data of a distribution transformer to be detected are received, extracting three-phase load data corresponding to each acquisition point in the three-phase daily load historical data;
calculating the sum of all phase line currents corresponding to the three-phase load data and averaging to obtain a corresponding three-phase load average value;
respectively calculating the current difference value between each phase line current corresponding to the three-phase load data and the average value of the three-phase load;
calculating the ratio of the maximum value in the current difference value to the three-phase load average value and converting the ratio into a percentage form to obtain the initial three-phase unbalance degree corresponding to the three-phase load data;
and determining the three-phase load unbalance activity corresponding to the distribution transformer to be detected based on the comparison result of each initial three-phase unbalance and a preset unbalance threshold.
Optionally, the step of determining the three-phase load imbalance activity corresponding to the distribution transformer to be detected based on a comparison result between each initial three-phase imbalance degree and a preset imbalance degree threshold value includes:
comparing each initial three-phase unbalance degree with a preset unbalance degree threshold value;
if the comparison result shows that the three-phase load unbalance is greater than or equal to the preset unbalance threshold, updating the initial three-phase unbalance to a first preset value;
if the comparison result shows that the three-phase load unbalance degree is smaller than the unbalance degree threshold value, updating the initial three-phase unbalance degree to a second preset value;
and calculating an average value between all the first preset values and the second preset values, and determining the average value as the three-phase load unbalance activity corresponding to the distribution transformer to be detected.
Optionally, the step of determining the three-phase load imbalance type to which the distribution transformer to be detected belongs according to the three-phase daily load historical data and a preset outlier threshold includes:
calculating corresponding Pearson correlation coefficients among all phase lines in the three-phase daily load historical data;
respectively calculating a difference value between a preset index threshold value and two Pearson correlation coefficients corresponding to each phase line, and summing the difference values to obtain corresponding blood-related affinity indexes;
and determining the three-phase load imbalance type of the distribution transformer to be detected according to the blood-related affinity index and a preset outlier threshold.
Optionally, the step of determining the three-phase load imbalance type to which the distribution transformer to be detected belongs according to the blood affinity index and a preset outlier threshold includes:
calculating the sum of all the blood-related affinity indexes and taking an average value to obtain a blood-related affinity average value;
calculating the difference between the blood relationship affinity index corresponding to each phase line and the blood relationship affinity average value respectively, and calculating the square sum to obtain the corresponding phase line outlier;
calculating the sum of all the phase line outliers to obtain the sum of the outliers;
calculating the ratio of the outlier sum value to a preset curve threshold value to obtain the three-phase daily load curve outlier corresponding to the three-phase daily load historical data;
judging whether the degree of outlier of the three-phase daily load curve is greater than or equal to a preset threshold value of the degree of outlier;
if so, determining that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is time-interval three-phase load imbalance;
and if not, determining that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is within the range of the three-phase load imbalance.
The invention also provides a three-phase load unbalance recognition system, which comprises:
the three-phase load unbalance activity determining module is used for determining the three-phase load unbalance activity corresponding to the distribution transformer to be detected according to the three-phase daily load historical data when the three-phase daily load historical data of the distribution transformer to be detected is received;
the three-phase load unbalance activity degree judging module is used for judging whether the three-phase load unbalance activity degree is greater than or equal to a preset activity degree threshold value or not;
the continuous three-phase load unbalance determining module is used for determining that the type of the three-phase load unbalance of the distribution transformer to be detected belongs to the continuous three-phase load unbalance if the type of the three-phase load unbalance is the continuous three-phase load unbalance;
and the three-phase load unbalance type determining module is used for determining the three-phase load unbalance type to which the distribution transformer to be detected belongs according to the three-phase daily load historical data and a preset outlier threshold if the three-phase daily load historical data is not the preset outlier threshold.
Optionally, the method further comprises:
and the alarm signal starting module is used for starting an alarm signal corresponding to the three-phase load unbalance type when the three-phase load unbalance type to which the distribution transformer to be detected belongs is determined.
The invention also provides an electronic device, which comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of implementing any one of the three-phase load imbalance identification methods.
The invention also provides a computer-readable storage medium on which a computer program is stored, which, when executed, implements any of the three-phase load imbalance identification methods described above.
According to the technical scheme, the invention has the following advantages:
according to the method, the three-phase daily load historical data of the distribution transformer to be detected is received, and the three-phase load unbalance activity corresponding to the distribution transformer to be detected is determined according to the three-phase daily load historical data. And then judging whether the three-phase load unbalance activity is greater than or equal to a preset activity threshold, and if the three-phase load unbalance activity is greater than or equal to the preset activity threshold, determining that the three-phase load unbalance type to which the distribution transformer to be detected belongs is continuous three-phase load unbalance. If the three-phase load unbalance activity is smaller than the preset activity threshold, the three-phase load unbalance type to which the distribution transformer to be detected belongs is determined according to the three-phase daily load historical data and the preset outlier threshold, and the technical problem that the accuracy of the determination result is low because the short-time or instantaneous three-phase load unbalance is caused by some random single-phase loads without considering that the short-time or instantaneous three-phase load unbalance is caused by the conventional three-phase load unbalance identification method is allowed in theory and engineering practice but the corresponding distribution transformer is listed as the category of three-phase load unbalance is solved. By setting two judgment indexes of an activity threshold value and an outlier threshold value, the three-phase load unbalance type to which the distribution transformer belongs is accurately identified, and misjudgment is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without inventive labor.
Fig. 1 is a flowchart illustrating steps of a method for identifying three-phase load imbalance according to an embodiment of the present invention;
fig. 2 is a flowchart illustrating steps of a method for identifying three-phase load imbalance according to a second embodiment of the present invention;
fig. 3 is a three-phase daily load curve diagram corresponding to the three-phase load historical data of the 10kV distribution transformer provided in the second embodiment of the present invention;
fig. 4 is a block diagram of a three-phase load imbalance identification system according to a third embodiment of the present invention.
Detailed Description
Three disadvantages arise due to the three-phase load imbalance of the distribution transformer: firstly, the output of the distribution transformer is reduced, the winding structure of the distribution transformer is designed according to the working condition of load balance operation, the performances of all phases are basically consistent, the rated capacity is equal, the maximum allowable output of the distribution transformer is limited by the rated capacity of each phase, when the distribution transformer operates under the working condition of three-phase load unbalance, one phase with light load has surplus capacity, so that the output of the distribution transformer is reduced, the more serious the three-phase load unbalance is, the more the output of the distribution transformer is reduced, therefore, the output capacity of the distribution transformer cannot reach the rated value when the three-phase load unbalance operates, the spare capacity of the distribution transformer is correspondingly reduced, and the overload capacity is also reduced. Secondly, the problem of low voltage of users is caused, when the neutral point of the distribution transformer is not grounded or the grounding resistance does not meet the technical requirements under the condition that the unbalance degree of the three-phase load is large, the neutral point will be displaced to cause the neutral line to have certain voltage, so that the voltage drop of the line is increased, and the power supply voltage of the line is lower. And thirdly, line loss of the line is increased, and when three-phase load is unbalanced, the neutral line has current to pass through, so that loss is generated, and the line loss is greatly increased. Therefore, it is important to accurately identify the three-phase load imbalance type to which the distribution transformer belongs.
The embodiment of the invention provides a method, a system, equipment and a medium for identifying three-phase load unbalance, which are used for solving the technical problems that the existing three-phase load unbalance identification method only gives a judgment result of yes or no, and does not consider that some random single-phase loads can cause short-time or instantaneous three-phase load unbalance, which is allowed in theory and engineering practice, but the method can list corresponding distribution transformers as the category of load three-phase unbalance, so that the accuracy of the judgment result is low.
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a flowchart illustrating a method for identifying a three-phase load imbalance according to an embodiment of the present invention.
The invention provides a three-phase load unbalance identification method, which comprises the following steps:
The distribution transformer to be detected is the distribution transformer needing to detect the working state of the three-phase load; the three-phase daily load historical data refers to that a load control terminal connected with a distribution transformer measures operation parameters of the distribution transformer such as voltage, current and power in real time by taking days as units, and data of a time point is uploaded to a metering automation system database every 15min, so that 96 measuring points are totally arranged 24 hours a day, namely the daily load historical data comprises 96 groups of three-phase load data. The three-phase load unbalance activity is the percentage of the number of three-phase unbalance more than 15% in the three-phase daily load historical data of the distribution transformer in the total number.
In the embodiment of the invention, when the three-phase daily load historical data of the distribution transformer to be detected is received, the three-phase load data corresponding to each acquisition point in the three-phase daily load historical data is extracted, the three-phase load unbalance degree corresponding to each three-phase load data is calculated, each three-phase load unbalance degree is compared with the preset unbalance degree threshold value, and the three-phase load unbalance activity degree corresponding to the distribution transformer to be detected is calculated according to the comparison result.
And 102, judging whether the three-phase load unbalance activity is greater than or equal to a preset activity threshold value or not.
The preset activity threshold value refers to a critical value corresponding to the three-phase load imbalance activity, when the three-phase load imbalance activity of the distribution transformer to be detected is greater than or equal to 95%, it is determined that the distribution transformer to be detected generates continuous three-phase load imbalance, the three-phase load imbalance type to which the distribution transformer to be detected belongs is continuous three-phase load imbalance, wherein 95% is an engineering practice experience value, and a corresponding activity threshold value can be set according to actual detection requirements.
In the embodiment of the invention, the three-phase load unbalance activity is compared with a preset activity threshold value, and whether the three-phase load unbalance activity is greater than or equal to the preset activity threshold value is determined.
And 103, if yes, determining that the type of the three-phase load unbalance of the distribution transformer to be detected belongs to the continuous three-phase load unbalance.
The continuous three-phase load unbalance refers to a three-phase load unbalance type corresponding to the condition that the three-phase load unbalance activity of the distribution transformer to be detected is greater than or equal to 95%.
In the embodiment of the invention, if the three-phase load unbalance activity of the distribution transformer to be detected is greater than or equal to the preset activity threshold, the three-phase load unbalance type to which the distribution transformer to be detected belongs is determined to be the continuous three-phase load unbalance.
And step 104, if not, determining the three-phase load unbalance type of the distribution transformer to be detected according to the three-phase daily load historical data and a preset outlier threshold.
The preset outlier threshold refers to a critical value corresponding to the three-phase daily load curve outlier, when the three-phase daily load curve outlier of the distribution transformer to be detected is greater than or equal to 0.5%, it is determined that a periodic three-phase load imbalance occurs in the distribution transformer to be detected, at this time, the three-phase load imbalance type to which the distribution transformer to be detected belongs is the periodic three-phase load imbalance, wherein 0.5% is an engineering practice experience value, and the outlier threshold can be set according to actual detection requirements, which is not limited in the embodiment of the present invention.
In the embodiment of the invention, Pearson correlation coefficients corresponding to all phase lines in the three-phase daily load historical data are calculated, and the difference between a preset index threshold and two Pearson correlation coefficients corresponding to all phase lines are calculated and summed to obtain corresponding blood-related affinity indexes. And determining the three-phase load imbalance type of the distribution transformer to be detected according to the blood-related affinity index and a preset outlier threshold.
In the embodiment of the invention, the three-phase daily load historical data of the distribution transformer to be detected is received, and the three-phase load unbalance activity corresponding to the distribution transformer to be detected is determined according to the three-phase daily load historical data. And then judging whether the three-phase load unbalance activity is greater than or equal to a preset activity threshold value or not, and if the three-phase load unbalance activity is greater than or equal to the preset activity threshold value, determining that the three-phase load unbalance type to which the distribution transformer to be detected belongs is continuous three-phase load unbalance. If the three-phase load unbalance activity is smaller than the preset activity threshold, the three-phase load unbalance type to which the distribution transformer to be detected belongs is determined according to the three-phase daily load historical data and the preset outlier threshold, and the technical problem that the accuracy of the determination result is low because the short-time or instantaneous three-phase load unbalance is caused by some random single-phase loads without considering that the short-time or instantaneous three-phase load unbalance is caused by the conventional three-phase load unbalance identification method is allowed in theory and engineering practice but the corresponding distribution transformer is listed as the category of three-phase load unbalance is solved. By setting two judgment indexes of an activity threshold value and an outlier threshold value, the three-phase load unbalance type to which the distribution transformer belongs is accurately identified, and misjudgment is avoided.
Referring to fig. 2, fig. 2 is a flowchart illustrating a method for identifying three-phase load imbalance according to a second embodiment of the present invention.
Further, step 201 may include the following sub-steps S11-S15:
and S11, when the three-phase daily load historical data of the distribution transformer to be detected are received, extracting the three-phase load data corresponding to each acquisition point in the three-phase daily load historical data.
The acquisition point is a time point when the negative control terminal acquires three-phase load data in one day, the distribution transformer is connected with the negative control terminal, the negative control terminal measures the voltage, current, power and other operation parameters in real time and uploads the data of one time point to the metering automation system database every 15min, so that 96 measurement points are available at 24 hours a day, namely 96 groups of three-phase current data are available. The metering automation database can be directly accessed in a database direct connection mode, so that the historical load data of the distribution transformer can be acquired. Or, according to the detection requirement, a corresponding timing transmission module may be set to transmit the three-phase daily load historical data of the distribution transformer to the identification device at a timing, so as to identify the three-phase load imbalance type to which the distribution transformer belongs, which is not limited in the embodiment of the present invention.
The three-phase load data refers to phase A current, phase B current and phase C current corresponding to each acquisition time point of the distribution transformer, namely three-phase current data corresponding to each acquisition time point of the distribution transformer.
In the embodiment of the invention, when the three-phase daily load historical data of the distribution transformer to be detected, which is acquired by the load control terminal, is received, the A-phase current, the B-phase current and the C-phase current corresponding to each acquisition point in the three-phase daily load historical data are extracted.
And S12, calculating the sum of all phase line currents corresponding to the three-phase load data and averaging to obtain the corresponding three-phase load average value.
The three-phase load average value is obtained by summing the A-phase current, the B-phase current and the C-phase current in the three-phase load data.
In the embodiment of the invention, the sum of the phase current A, the phase current B and the phase current C in each three-phase load data is calculated respectively, and the average value is correspondingly obtained to obtain the three-phase load average value corresponding to each three-phase load data.
And S13, respectively calculating the current difference between the current of each phase line corresponding to the three-phase load data and the average value of the three-phase load.
The phase line current refers to the phase A current, the phase B current and the phase C current corresponding to the three-phase load data.
In the embodiment of the invention, the A-phase current, the B-phase current and the C-phase current in each three-phase load data are respectively subjected to difference value calculation with the corresponding three-phase load average value to obtain the current difference value between each phase line current and the three-phase load average value of each three-phase load data.
And S14, calculating the ratio of the maximum value in the current difference value to the three-phase load average value, and converting the ratio into a percentage form to obtain the initial three-phase unbalance degree corresponding to the three-phase load data.
The initial three-phase unbalance degree is obtained by calculating three-phase load data, and the specific calculation process is shown as the following formula:
in the formula
（i=1, 2.., 96) represents an initial three-phase load unbalance,
representing the a-phase current in the three-phase load data,
representing the B-phase current in the three-phase load data,
representing the C-phase current in the three-phase load data,
representing the three-phase load average.
In the embodiment of the invention, the current difference between each phase line current corresponding to each three-phase load data and the corresponding three-phase load average value is calculated, the maximum value of the current difference is selected, the ratio of the maximum value of the current difference to the three-phase load average value is calculated and converted into a percentage form, and the initial three-phase unbalance degree corresponding to the three-phase load data is obtained.
And S15, determining the three-phase load unbalance activity corresponding to the distribution transformer to be detected based on the comparison result of each initial three-phase unbalance with a preset unbalance threshold value.
Further, step S15 may include the following sub-steps S151-S154:
and S151, comparing each initial three-phase unbalance degree with a preset unbalance degree threshold value.
In the embodiment of the invention, each initial three-phase unbalance degree is respectively compared with a preset unbalance degree threshold value.
And S152, if the comparison result shows that the three-phase load unbalance degree is greater than or equal to the preset unbalance degree threshold value, updating the initial three-phase unbalance degree to a first preset value.
In the embodiment of the invention, if the comparison result of the initial three-phase unbalance degrees with the preset unbalance degree threshold respectively indicates that the three-phase load unbalance degree is greater than or equal to the preset unbalance degree threshold, the initial three-phase unbalance degree is updated to the first preset value.
And S153, if the comparison result shows that the three-phase load unbalance degree is smaller than the unbalance degree threshold value, updating the initial three-phase unbalance degree to a second preset value.
In the embodiment of the invention, if the comparison result of the initial three-phase unbalance degrees with the preset unbalance degree threshold respectively indicates that the three-phase load unbalance degree is less than the unbalance degree threshold, the initial three-phase unbalance degree is updated to a second preset value.
Setting the unbalance threshold value to be 15%, the first preset value to be 1, and the second preset value to be 0, then the updated initial three-phase unbalance is:
and S154, calculating an average value between all the first preset values and all the second preset values, and determining the average value as the three-phase load unbalance activity corresponding to the distribution transformer to be detected.
In the embodiment of the invention, the sum of all the first preset values and the second preset values is calculated and averaged, and the obtained average value is determined as the three-phase load unbalance activity corresponding to the distribution transformer to be detected.
If the three-phase daily load historical data of the distribution transformer to be detected contains 96-point three-phase load data, the three-phase load imbalance activity degree corresponding to the distribution transformer to be detected is as follows:
in the formula
（iAnd =1, 2., 96) represents the updated initial three-phase unbalance, i.e., the first preset value or the second preset value.
In the embodiment of the invention, the three-phase load unbalance activity is compared with a preset activity threshold value, and whether the three-phase load unbalance activity is greater than or equal to the preset activity threshold value is determined.
And 203, if yes, determining that the three-phase load unbalance type of the distribution transformer to be detected is continuous three-phase load unbalance.
In the embodiment of the invention, when the three-phase load unbalance activity is greater than or equal to the preset activity threshold, the three-phase load unbalance type of the distribution transformer to be detected is determined to be the continuous three-phase load unbalance.
And 204, if not, determining the three-phase load unbalance type of the distribution transformer to be detected according to the three-phase daily load historical data and a preset outlier threshold.
Further, step 204 may include the following sub-steps S21-S23:
and S21, calculating the Pearson correlation coefficient corresponding to each phase line in the three-phase daily load historical data.
The Pearson correlation coefficient is used for measuring whether two data sets are on the same line or not, and is used for measuring the linear relation between distance variables, and calculation formulas of the Pearson correlation coefficient between every two phase lines are the same. Pearson correlation coefficient of A-phase daily load curve and B-phase daily load curve
The calculation formula of (a) is as follows:
in the embodiment of the invention, a three-phase daily load curve with a measuring point serial number as an abscissa and a current value as an ordinate is drawn according to 96-point three-phase load data corresponding to three-phase daily load historical data, and the pearson correlation coefficient between the phase daily load curves is respectively calculated through a calculation formula corresponding to the pearson correlation coefficient.
And S22, respectively calculating the difference between the preset index threshold and the two Pearson correlation coefficients corresponding to each phase line, and summing the difference to obtain the corresponding blood affinity index.
The blood affinity index refers to the blood affinity index of the A-phase daily load curve and the B, C-phase daily load curve, the blood affinity index of the B-phase daily load curve and the A, C-phase daily load curve, and the blood affinity index of the C-phase daily load curve and the A, B-phase daily load curve, respectively
、
、
Expressed, the corresponding calculation formula is:
wherein the preset index threshold value is 1,
(or
) Representing the Pearson correlation coefficient of the A-phase daily load curve and the B-phase daily load curve,
(or
) Representing the Pearson correlation coefficient of the A-phase daily load curve and the C-phase daily load curve,
(or
) And represents the Pearson correlation coefficient of the phase B daily load curve and the phase C daily load curve.
In the embodiment of the present invention, the preset exponential threshold is usually set to 1, the preset threshold is respectively calculated as a difference between two pearson correlation coefficients corresponding to each phase line, and the two obtained differences are summed to obtain the blood-related affinity index corresponding to each phase line.
And S23, determining the three-phase load imbalance type of the distribution transformer to be detected according to the blood affinity index and a preset outlier threshold.
Further, step S23 may include the following sub-steps S231-S237:
s231, calculating the sum of all the blood relationship affinity indexes and averaging to obtain a blood relationship affinity average value.
In the embodiment of the invention, the blood-related affinity indexes corresponding to the A-phase daily load curve, the B-phase daily load curve and the C-phase daily load curve in the three-phase daily load historical data of the distribution transformer to be detected are summed, and the average value of the summed values is obtained to obtain the blood-related affinity average value corresponding to the three-phase daily load historical data.
And S232, calculating the difference between the blood relationship affinity index corresponding to each phase line and the blood relationship affinity average value respectively, and solving the sum of squares to obtain the corresponding phase line outlier.
The phase line refers to a phase A daily load curve, a phase B daily load curve and a phase C daily load curve.
In the embodiment of the invention, the difference value calculation is carried out on the A-phase daily load curve, the B-phase daily load curve and the C-phase daily load curve and the blood relationship closeness average value respectively, and the square sum of each difference value is calculated to obtain the phase line outlier corresponding to the A-phase daily load curve, the B-phase daily load curve and the C-phase daily load curve.
And S233, calculating the sum of the outliers of all the phase lines to obtain the sum of the outliers.
In the embodiment of the invention, the phase line outliers corresponding to the A-phase daily load curve, the B-phase daily load curve and the C-phase daily load curve are calculated to obtain the outliers and the values.
And S234, calculating the ratio of the outlier sum value to a preset curve threshold value to obtain the three-phase daily load curve outlier corresponding to the three-phase daily load historical data.
The curve threshold is a threshold which needs to be set based on the calculation of the three-phase daily load curve outlier, and the preset curve threshold is 2.
In the embodiment of the invention, the ratio of the calculated outlier sum value of the phase line outliers corresponding to the A-phase daily load curve, the B-phase daily load curve and the C-phase daily load curve to the preset curve threshold is obtained to obtain the three-phase daily load curve outlier corresponding to the three-phase daily load historical data. And lambda is the degree of outlier of the three-phase daily load curve, represents the coincidence degree of the A, B, C three-phase daily load curve, and the larger lambda is the larger degree of unbalance of the three-phase load. The calculation process of the three-phase daily load curve outlier is shown in the following formula:
wherein,
representing the blood affinity index of the phase A daily load curve and the B, C daily load curve,
representing the blood affinity index of the phase B daily load curve and the A, C daily load curve,
the blood affinity index of the phase C daily load curve and the phase A, B daily load curve is represented.
S235, judging whether the degree of outlier of the three-phase daily load curve is larger than or equal to a preset threshold value of the degree of outlier.
In the embodiment of the invention, the three-phase daily load curve outlier is compared with a preset outlier threshold value, and whether the three-phase daily load curve outlier is greater than or equal to the preset outlier threshold value is determined, wherein the preset outlier threshold value is usually 0.5%.
And S236, if so, determining that the three-phase load unbalance type of the distribution transformer to be detected belongs to is time-interval three-phase load unbalance.
In the embodiment of the invention, when the degree of divergence of the three-phase daily load curve is greater than or equal to the preset degree of divergence threshold, the distribution transformer is considered to generate the time-interval three-phase load imbalance, and the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is determined to be the time-interval three-phase load imbalance.
And S237, if not, determining that the type of the three-phase load unbalance of the distribution transformer to be detected belongs to is the three-phase load unbalance within the range.
In the embodiment of the invention, when the degree of divergence of the daily load curve of the three phases is smaller than the preset degree of divergence threshold, the distribution transformer is considered to generate three-phase load imbalance which belongs to short-time or instantaneous three-phase load imbalance allowed in theory and engineering practice, and the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is determined to be three-phase load imbalance within the range.
And step 205, when the three-phase load unbalance type of the distribution transformer to be detected is determined, starting an alarm signal corresponding to the three-phase load unbalance type.
The alarm signal comprises three types of continuous abnormal alarm, time-interval abnormal alarm and non-alarm, the continuous abnormal alarm and the time-interval abnormal alarm are respectively connected with the corresponding alarm units, and when the continuous abnormal alarm or the time-interval abnormal alarm is started, the corresponding alarm information is timely sent to the corresponding manager or the corresponding alarm prompt is sent through the alarm device.
In the embodiment of the invention, when the three-phase load unbalance type of the distribution transformer to be detected is continuous three-phase load unbalance, a continuous abnormity alarm is started. And when the three-phase load unbalance type of the distribution transformer to be detected is periodical three-phase load unbalance, starting periodical abnormity alarm. And when the three-phase load unbalance type of the distribution transformer to be detected is three-phase load unbalance in the range, no alarm is given. According to the alarm signal that three-phase unbalanced load type corresponds, in time remind the technical staff to handle, according to the three-phase unbalanced load type that distribution transformer belongs to, formulate the treatment scheme, accurate guide treatment measures.
For example, the three-phase load history data of a certain 10kV distribution transformer on a certain day is shown in the following tables 1 and 2:
TABLE 1
TABLE 2
Calculating the three-phase load unbalance activity corresponding to the three-phase daily load historical data of the 10kV distribution transformer through the steps of the examplek=6.25% < 90%, continuously calculating the second judgment index three-phase daily load curve outlier lambda =1.10% > 0.5%, judging that the three-phase load unbalance type to which the 10kV distribution transformer belongs is time-interval three-phase load unbalance, and starting time-interval abnormal alarm.
As shown in fig. 3, fig. 3 is a three-phase daily load graph having the serial number of the measurement point as the abscissa and the current value as the ordinate, corresponding to the three-phase daily load history data of the 10kV distribution transformer in table 1 and table 2, in which a phase indicates a-phase current, B phase indicates B-phase current, and C phase indicates C-phase current. Because 6 measurement points (accumulated for 90 minutes) in the phase A have larger deviation with other two points, the three-phase imbalance can be roughly judged as the three-phase imbalance according to the existing method for judging the three-phase imbalance, and the three-phase load imbalance type of the 10kV distribution transformer can not be determined to be the time-interval three-phase load imbalance or the continuous three-phase load imbalance, so that the accurate formulation of control measures can not be guided.
In the embodiment of the invention, the three-phase daily load historical data of the distribution transformer to be detected is received, and the three-phase load data corresponding to each acquisition point in the three-phase daily load historical data is extracted. And calculating the sum of all phase line currents corresponding to the three-phase load data and averaging to obtain a corresponding three-phase load average value. And respectively calculating current difference values between the currents of the phase lines corresponding to the three-phase load data and the average value of the three-phase load, calculating the ratio of the maximum value in the current difference values to the average value of the three-phase load, and converting the ratio into a percentage form to obtain the initial three-phase unbalance degree corresponding to the three-phase load data.
And determining the three-phase load unbalance activity corresponding to the distribution transformer to be detected based on the comparison result of each initial three-phase unbalance and a preset unbalance threshold. And determining whether the three-phase load unbalance type of the distribution transformer to be detected is continuous three-phase load unbalance by judging whether the three-phase load unbalance activity is greater than or equal to a preset activity threshold value. And if not, calculating the Pearson correlation coefficient corresponding to each phase line in the three-phase daily load historical data, respectively calculating the difference between a preset index threshold and two Pearson correlation coefficients corresponding to each phase line, and summing to obtain the corresponding blood-related affinity index. Calculating the sum of all the blood-related affinity indexes and averaging to obtain a blood-related affinity average value, respectively calculating the difference between the blood-related affinity indexes corresponding to all the phase lines and the blood-related affinity average value and calculating the sum of squares to obtain corresponding phase line outliers, calculating the sum of all the phase line outliers to obtain an outlier sum value, and calculating the ratio of the outlier sum value to a preset curve threshold to obtain the three-phase daily load curve outliers corresponding to the three-phase daily load historical data.
Judging whether the degree of outlier of the three-phase daily load curve is greater than or equal to a preset threshold value of the degree of outlier, and if so, determining that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is a time-interval three-phase load imbalance; and if not, determining that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is within the range of the three-phase load imbalance. And when the three-phase load unbalance type of the distribution transformer to be detected is the continuous three-phase load unbalance, starting a continuous abnormal alarm. And when the three-phase load unbalance type of the distribution transformer to be detected is periodical three-phase load unbalance, starting periodical abnormity alarm. And when the three-phase load unbalance type of the distribution transformer to be detected is three-phase load unbalance in the range, no alarm is given. The three-phase load unbalance type to which the distribution transformer belongs is accurately identified by setting two judgment indexes, namely the activeness threshold value and the outlier threshold value, so that a treatment scheme is formulated according to the three-phase load unbalance type to which the distribution transformer belongs, and treatment measures are accurately guided.
Referring to fig. 4, fig. 4 is a block diagram illustrating a three-phase load imbalance identification system according to a third embodiment of the present invention.
The embodiment of the invention provides a three-phase load unbalance recognition system, which comprises:
the three-phase load unbalance activity determining module 401 is configured to determine, when three-phase daily load historical data of the distribution transformer to be detected is received, a three-phase load unbalance activity corresponding to the distribution transformer to be detected according to the three-phase daily load historical data.
The three-phase unbalanced load activity determining module 402 is configured to determine whether the three-phase unbalanced load activity is greater than or equal to a preset activity threshold.
And a persistent three-phase load imbalance determining module 403, configured to determine that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is persistent three-phase load imbalance if the type of the three-phase load imbalance belongs.
And a three-phase load unbalance type determining module 404, configured to determine, if the three-phase load unbalance type is not determined, a three-phase load unbalance type to which the distribution transformer to be detected belongs according to the three-phase daily load historical data and a preset outlier threshold.
Optionally, the system further comprises:
and the alarm signal starting module is used for starting an alarm signal corresponding to the three-phase load unbalance type when the three-phase load unbalance type to which the distribution transformer to be detected belongs is determined.
Optionally, the three-phase load imbalance activity determination module 401 includes:
and the three-phase load data extraction module is used for extracting three-phase load data corresponding to each acquisition point in the three-phase daily load historical data when receiving the three-phase daily load historical data of the distribution transformer to be detected.
And the three-phase load average value obtaining module is used for calculating the sum of all phase line currents corresponding to the three-phase load data and averaging to obtain the corresponding three-phase load average value.
And the current difference value calculating module is used for calculating the current difference value between each phase line current corresponding to the three-phase load data and the average value of the three-phase load respectively.
And the initial three-phase unbalance calculation module is used for calculating the ratio between the maximum value in the current difference value and the three-phase load average value and converting the ratio into a percentage form to obtain the initial three-phase unbalance corresponding to the three-phase load data.
And the three-phase unbalanced load activity determining submodule is used for determining the three-phase unbalanced load activity corresponding to the distribution transformer to be detected based on the comparison result of each initial three-phase unbalanced load and a preset unbalanced load threshold value.
Optionally, the three-phase load imbalance activity determination submodule may perform the following steps:
comparing each initial three-phase unbalance degree with a preset unbalance degree threshold value;
if the comparison result shows that the three-phase load unbalance degree is larger than or equal to the preset unbalance degree threshold value, updating the initial three-phase unbalance degree to a first preset value;
if the comparison result shows that the three-phase load unbalance is smaller than the unbalance threshold, updating the initial three-phase unbalance to a second preset value;
and calculating an average value between all the first preset values and all the second preset values, and determining the average value as the three-phase load unbalance activity corresponding to the distribution transformer to be detected.
Optionally, the three-phase load imbalance type determining module 404 includes:
and the Pearson correlation coefficient calculating module is used for calculating Pearson correlation coefficients corresponding to all phase lines in the three-phase daily load historical data.
And the blood affinity index obtaining module is used for respectively calculating the difference between a preset index threshold and two Pearson correlation coefficients corresponding to each phase line and summing the difference to obtain the corresponding blood affinity index.
And the three-phase load unbalance type determining submodule is used for determining the three-phase load unbalance type to which the distribution transformer to be detected belongs according to the blood-related affinity index and a preset outlier threshold.
Optionally, the three-phase load imbalance type determining submodule may perform the steps of:
calculating the sum of all the blood relationship affinity indexes and taking an average value to obtain a blood relationship affinity average value;
calculating the difference between the blood relationship affinity index corresponding to each phase line and the blood relationship affinity average value respectively, and solving the square sum to obtain the corresponding phase line outlier;
calculating the sum of the outliers of all the phase lines to obtain the sum of the outliers;
calculating the ratio of the outlier and the preset curve threshold value to obtain the three-phase daily load curve outlier corresponding to the three-phase daily load historical data;
judging whether the degree of outlier of the three-phase daily load curve is greater than or equal to a preset threshold value of the degree of outlier;
if so, determining that the three-phase load unbalance type of the distribution transformer to be detected belongs to is time-interval three-phase load unbalance;
and if not, determining that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is within the range of the three-phase load imbalance.
An embodiment of the present invention further provides an electronic device, where the electronic device includes: the computer system comprises a memory and a processor, wherein a computer program is stored in the memory; the computer program, when executed by the processor, causes the processor to perform a method of identifying a three-phase load imbalance as in any one of the embodiments described above.
The memory may be an electronic memory such as a flash memory, an EEPROM (electrically erasable programmable read only memory), an EPROM, a hard disk, or a ROM. The memory has a storage space for program code for performing any of the method steps of the above-described method. For example, the memory space for the program code may comprise respective program codes for implementing the respective steps in the above method, respectively. The program code can be read from and written to one or more computer program products. These computer program products comprise a program code carrier such as a hard disk, a Compact Disc (CD), a memory card or a floppy disk. The program code may be compressed, for example, in a suitable form. The codes, when executed by a computing processing device, cause the computing processing device to perform the steps of the three-phase load imbalance identification method described above.
The embodiment of the invention also provides a computer readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the method for identifying three-phase load imbalance according to any one of the embodiments is implemented.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, a division of a unit is merely a logical division, and an actual implementation may have another division, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A three-phase load unbalance identification method is characterized by comprising the following steps:
when three-phase daily load historical data of a distribution transformer to be detected are received, determining three-phase load unbalance activity corresponding to the distribution transformer to be detected according to the three-phase daily load historical data;
judging whether the three-phase load unbalance activity is greater than or equal to a preset activity threshold value or not;
if so, determining that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is continuous three-phase load imbalance;
and if not, determining the three-phase load unbalance type of the distribution transformer to be detected according to the three-phase daily load historical data and a preset outlier threshold.
2. The method of identifying three-phase load imbalance of claim 1, further comprising:
and when the three-phase load unbalance type to which the distribution transformer to be detected belongs is determined, starting an alarm signal corresponding to the three-phase load unbalance type.
3. The method for identifying the three-phase load unbalance according to claim 1, wherein the step of determining the three-phase load unbalance activity corresponding to the distribution transformer to be detected according to the three-phase daily load history data when the three-phase daily load history data of the distribution transformer to be detected is received comprises:
when three-phase daily load historical data of a distribution transformer to be detected are received, extracting three-phase load data corresponding to each acquisition point in the three-phase daily load historical data;
calculating the sum of all phase line currents corresponding to the three-phase load data and averaging to obtain a corresponding three-phase load average value;
respectively calculating the current difference value between each phase line current corresponding to the three-phase load data and the average value of the three-phase load;
calculating the ratio of the maximum value in the current difference value to the three-phase load average value and converting the ratio into a percentage form to obtain the initial three-phase unbalance degree corresponding to the three-phase load data;
and determining the three-phase load unbalance activity corresponding to the distribution transformer to be detected based on the comparison result of each initial three-phase unbalance and a preset unbalance threshold.
4. The method for identifying the three-phase load unbalance according to claim 3, wherein the step of determining the three-phase load unbalance activity corresponding to the distribution transformer to be detected based on the comparison result between each initial three-phase unbalance and a preset unbalance threshold value comprises:
comparing each initial three-phase unbalance degree with a preset unbalance degree threshold value;
if the comparison result shows that the three-phase load unbalance degree is larger than or equal to the preset unbalance degree threshold value, updating the initial three-phase unbalance degree to a first preset value;
if the comparison result shows that the three-phase load unbalance degree is smaller than the unbalance degree threshold value, updating the initial three-phase unbalance degree to a second preset value;
and calculating an average value between all the first preset values and the second preset values, and determining the average value as the three-phase load unbalance activity corresponding to the distribution transformer to be detected.
5. The method for identifying the three-phase load unbalance according to claim 1, wherein the step of determining the three-phase load unbalance type to which the distribution transformer to be detected belongs according to the three-phase daily load historical data and a preset outlier threshold comprises:
calculating corresponding Pearson correlation coefficients among all phase lines in the three-phase daily load historical data;
respectively calculating a difference value between a preset index threshold value and two Pearson correlation coefficients corresponding to each phase line, and summing the difference values to obtain corresponding blood-related affinity indexes;
and determining the three-phase load imbalance type of the distribution transformer to be detected according to the blood-related affinity index and a preset outlier threshold.
6. The method for identifying the three-phase load imbalance according to claim 5, wherein the step of determining the three-phase load imbalance type to which the distribution transformer to be detected belongs according to the blood affinity index and a preset outlier threshold comprises:
calculating the sum of all the blood-related affinity indexes and taking an average value to obtain a blood-related affinity average value;
calculating the difference between the blood relationship affinity index corresponding to each phase line and the blood relationship affinity average value respectively, and calculating the square sum to obtain the corresponding phase line outlier;
calculating the sum of all the phase line outliers to obtain the sum of the outliers;
calculating the ratio of the outlier sum value to a preset curve threshold value to obtain the three-phase daily load curve outlier corresponding to the three-phase daily load historical data;
judging whether the degree of outlier of the three-phase daily load curve is greater than or equal to a preset threshold value of the degree of outlier;
if so, determining that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is time-interval three-phase load imbalance;
and if not, determining that the type of the three-phase load imbalance to which the distribution transformer to be detected belongs is within the range of the three-phase load imbalance.
7. A three-phase load imbalance identification system, comprising:
the system comprises a three-phase load unbalance activity determining module, a data processing module and a data processing module, wherein the three-phase load unbalance activity determining module is used for determining the three-phase load unbalance activity corresponding to a distribution transformer to be detected according to three-phase daily load historical data when the three-phase daily load historical data of the distribution transformer to be detected are received;
the three-phase load unbalance activity degree judging module is used for judging whether the three-phase load unbalance activity degree is greater than or equal to a preset activity degree threshold value or not;
the continuous three-phase load unbalance determining module is used for determining that the type of the three-phase load unbalance of the distribution transformer to be detected belongs to the continuous three-phase load unbalance if the type of the three-phase load unbalance is the continuous three-phase load unbalance;
and the three-phase load unbalance type determining module is used for determining the three-phase load unbalance type to which the distribution transformer to be detected belongs according to the three-phase daily load historical data and a preset outlier threshold if the three-phase daily load historical data is not the preset outlier threshold.
8. The three-phase load imbalance identification system of claim 7, further comprising:
and the alarm signal starting module is used for starting an alarm signal corresponding to the three-phase load unbalance type when the three-phase load unbalance type to which the distribution transformer to be detected belongs is determined.
9. An electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer program, when executed by the processor, causes the processor to perform the steps of the three-phase load imbalance identification method according to any one of claims 1 to 6.
10. A computer-readable storage medium, on which a computer program is stored, which computer program, when being executed, carries out a method for identifying a three-phase load imbalance according to any one of claims 1 to 6.
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