CN112613734A - Electric energy state evaluation index selection method - Google Patents

Electric energy state evaluation index selection method Download PDF

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CN112613734A
CN112613734A CN202011529588.1A CN202011529588A CN112613734A CN 112613734 A CN112613734 A CN 112613734A CN 202011529588 A CN202011529588 A CN 202011529588A CN 112613734 A CN112613734 A CN 112613734A
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刘超
王璐
安运志
袁航
段志尚
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Marketing Service Center Of State Grid Xinjiang Electric Power Co Ltd Capital Intensive Center Metering Center
Beijing Zhixiang Technology Co Ltd
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Abstract

The invention belongs to an index selection and determination method, and particularly relates to an electric energy state evaluation index selection method. It includes: the method comprises the following steps: sampling; sampling basic parameters; step two: normalizing the data; carrying out data normalization on the sampling parameters; step three: calculating a compensation value; calculating three compensation values; step four: calculating the weight; calculating the weights of different parameters; step five: weight revision; revising the weight; step six: selecting parameters; according to the corrected weight value WjAnd selecting parameters. The invention has the following remarkable effects: (1) the method selects a plurality of specific indexes which have large influence on the operation of the power grid as evaluation basic indexes; (2) calculating the basic weight of each index through the correlation of the parameters; (3) by correcting the basic weight, the indexes can reflect the running state of the existing power grid to the greatest extent.

Description

Electric energy state evaluation index selection method
Technical Field
The invention belongs to an index selection and determination method, and particularly relates to an electric energy state evaluation index selection method.
Background
The power grid is one of essential infrastructure of modern society production life, and the quality of production life is directly influenced to the good or bad of power grid operation. In the prior art, the evaluation of a power grid has many dimensions, such as an economic evaluation mode established by the power grid, a quality evaluation mode operated by the power grid, an evaluation mode of operating efficiency of the power grid and the like.
These evaluation methods have in common that: and evaluating the power grid by using the determined index dimension and the determined weight. However, the grid is not invariable in operation. Along with the change of seasons, the electricity consumption of residents and the electricity consumption of industry are very different; under the influence of an economic cycle, industrial electricity also shows periodic regular change; when an emergency occurs, the index with a low original weight suddenly becomes important, and the like.
The method solves the problem that the power grid cannot be evaluated in real time by a rigid and fixed evaluation index in the prior art, so that an electric energy state evaluation index selection method needs to be established.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for selecting an electric energy state evaluation index.
The invention is realized by the following steps: a method for selecting an electric energy state evaluation index comprises the following steps:
the method comprises the following steps: sampling
Sampling basic parameters;
step two: data normalization
Carrying out data normalization on the sampling parameters;
step three: calculating a compensation value
Calculating three compensation values;
step four: calculating weights
Calculating the weights of different parameters;
step five: weight revision
Revising the weight;
step six: parameter selection
According to the corrected weight value WjAnd selecting parameters.
The method for selecting an electric energy state evaluation index as described above, wherein the sampling parameter in the first step includes: voltage deviation, frequency deviation, three-phase unbalance, harmonic ratio, voltage sag, line loss rate,
wherein the content of the first and second substances,
voltage deviation: the difference between the actual voltage at each point and the nominal voltage of the system, expressed in percentage, i.e.
Figure BDA0002851813770000021
Wherein U is the actual voltage, UNThe system nominal voltage is adopted, the delta U is the voltage deviation, the formula is only a calculation formula of the voltage deviation, when a plurality of groups of sampling are needed, each voltage deviation is calculated by adopting the formula, for the three-phase voltage, the average value of the three-phase voltage is taken as the actual voltage,
frequency deviation: difference of actual frequency from nominal frequency, i.e.
Δf＝|f-fN|
Where f is the actual frequency, fNFor the nominal frequency, Δ f is the voltage deviation, the above formula is only the calculation formula of the frequency deviation, when a plurality of sets of sampling are required, each frequency deviation is calculated by the above formula,
three-phase unbalance: is the degree of inconsistency of three-phase voltage amplitudes in the power system, i.e.
Figure BDA0002851813770000031
Wherein max represents taking the maximum value, min represents taking the minimum value,
Figure BDA0002851813770000032
UA，UB，UCis an effective value of the three-phase voltage,
harmonic ratio: the ratio of harmonic to total amount is taken as the ratio of the sum of harmonics within 10 to fundamental wave, i.e. the ratio
Figure BDA0002851813770000033
Wherein R represents the harmonic ratio, UHarmonic ofThe ith harmonic of U is represented, for the multiple sampling condition, the harmonic calculation within 10 times is carried out on the U obtained by each sampling, the harmonic ratio is calculated by the calculation result by the formula, the respective harmonic ratios are respectively calculated for the three-phase electricity, then the harmonic ratios of the three-phase electricity are averaged to be used as the total harmonic ratio numerical value, for the multiple sampling condition of the three-phase electricity, the three-phase electricity is respectively sampled and the harmonic ratios are respectively calculated when sampling is carried out at a certain time point, then the harmonic ratios of the three-phase electricity are averaged to be used as the total harmonic ratio numerical value sampled at the time point, the sampling of all time points is sequentially completed, and the harmonic ratio sample data of all time points are obtained,
voltage sag: the effective value of the power supply voltage is rapidly reduced to 90% -10% of the rated value, the sampling content of the method comprises the voltage value and the duration of voltage sag, and the sampling comprises amplitude reduction UDescendAnd duration tDescendTaking the product of the two as the final sampling value of the project, recording the parameter as 0 if the three phases do not have voltage sag at the same sampling time point for the three-phase power, if the voltage sag occurs, firstly taking the product of the decreasing amplitude of each voltage sag and the time, and then taking the maximum value of the product as the parameter of the current sampling,
line loss rate: line loss is the energy loss generated by the transmission of electric energy through a transmission line, and the ratio of the line loss is the line loss rate, namely
The line loss rate is (power supply amount-electricity sales amount)/electricity purchase amount × 100%.
The method for selecting the electric energy state evaluation index comprises the following steps of sampling for 20-40 seconds; the sampling frequency is 10-1000 times of the power grid frequency; the interval time ranges from 30 seconds to 10 minutes; the total time of sampling is 1-24 hours.
The method for selecting the electric energy state evaluation index is characterized in that the sampling time in the first step is preferably 30 seconds; the sampling frequency is preferably 300 times; the interval time is preferably 1 minute; the total sampling time ensures a minimum of 10 samples.
The method for selecting the electric energy state evaluation index comprises the following steps of normalizing by the following formula,
Figure BDA0002851813770000041
the normalized data retains only the three bits of data after the decimal point,
forming a normalized data matrix after normalization
Figure BDA0002851813770000051
The rows represent different sampling time points, and the columns represent different data, specifically, the first column represents voltage deviation, the second column represents frequency deviation, the third column represents three-phase imbalance, the fourth column represents harmonic proportion, the fifth column represents voltage sag, and the sixth column represents line loss rate, so that n in the present application is 6.
The method for selecting the power state assessment index as described above, wherein the third step includes,
step 3.1: mean value
Taking the average value of each line of data, namely calculating each line of data by adopting the following formula
Figure BDA0002851813770000052
Where m is the number of rows in the matrix B in step two, j represents the number of columns, i.e. the calculation is performed for the jth column, j has a value in the range of 1 to n, where n is 6,
b is obtained by the above calculation1 are all、b2 are all、b3 are all、b4 are all、b5 are all、b6 are allSetting 6 weight correction values k1 are all、k2 are all、k3 are all、k4 are all、k5 are all、k6 are allThe 6 weight correction values correspond to 6 parameters, and the specific numerical values of the 6 weight correction values are determined according to the following principle,
anchor point
Figure BDA0002851813770000053
If it is
Figure BDA0002851813770000054
Then let kj all are＝0；
If it is
Figure BDA0002851813770000061
Then let kj all are＝0.5；
If it is
Figure BDA0002851813770000062
Then let kj all are＝1，
Step 3.2: median number
Taking the median of each row of data, if the row of data is odd, directly taking the median, if the row of data is even, taking the mean value of the two numbers at the middle as the median,
b is obtained by the above calculation1 in、bIn 2 (2)、b3 in、b4 in、b5 in、b6 inSetting 6 weight correction valuesk1 in、kIn 2 (2)、k3 in、k4 in、k5 in、k6 inThe 6 weight correction values correspond to 6 parameters, and the specific numerical values of the 6 weight correction values are determined according to the following principle,
anchor point
Figure BDA0002851813770000063
If it is
Figure BDA0002851813770000064
Then let kj in＝0；
If it is
Figure BDA0002851813770000065
Then let kj in＝0.5；
If it is
Figure BDA0002851813770000066
Then let kj in＝1，
Step 3.3: variance (variance)
Taking variance for each column of data, namely calculating the variance for each column of data by adopting the following formula
Figure BDA0002851813770000067
Where m is the number of rows in the matrix B in step two, j represents the number of columns, i.e. the calculation is performed for the jth column, j has a value in the range 1-n, where n is 6,
Figure BDA0002851813770000071
b is obtained by the above calculation1 Square、b2 Square、b3 Square、b4-square、b5 Square、b6 SquareSetting 6 weight correction values k1 Square、k2 Square、k3 Square、k4-square、k5 Square、k6 SquareThe 6 weight correction values correspond to 6 parameters, and the specific numerical values of the 6 weight correction values are determined according to the following principle,
anchor point
Figure BDA0002851813770000072
If it is
Figure BDA0002851813770000073
Then let kSquare j＝0；
If it is
Figure BDA0002851813770000074
Then let kSquare j＝0.5；
If it is
Figure BDA0002851813770000075
Then let kSquare j＝1。
The method for selecting the electric energy state evaluation index as described above, wherein the fourth step includes,
order to
Figure BDA0002851813770000076
When all p areijAfter the calculation, E is calculated by the following formulaj
Figure BDA0002851813770000077
Where ln () represents the logarithm with the base constant e, m is the number of rows of the matrix B in step two,
if p isijWhen the value is equal to 0, then order Ej＝0，
Weight WjIs calculated by the following formula
Figure BDA0002851813770000081
The method for selecting the electric energy state evaluation index as described above, wherein the fifth step includes,
weight value WjAverage value of (2)
Figure BDA0002851813770000082
Figure BDA0002851813770000083
If k isj all areWhen the value is 0, then WjThe value of (d) is unchanged;
if k isj all areIf 0.5, the corrected weight is set to
Figure BDA0002851813770000084
If k isj all areIf 1, let the corrected weight be
Figure BDA0002851813770000085
If k isj inWhen the value is 0, then WjThe value of (d) is unchanged;
if k isj inIf 0.5, the corrected weight is set to
Figure BDA0002851813770000086
If k isj inIf 1, let the corrected weight be
Figure BDA0002851813770000087
If k isSquare jWhen the value is 0, then WjThe value of (d) is unchanged;
if k isSquare jIf 0.5, the corrected weight is set to
Figure BDA0002851813770000088
If k isSquare jIf 1, let the corrected weight be
Figure BDA0002851813770000089
The method for selecting the electric energy state evaluation index comprises the following steps of selecting one of the following two schemes,
the first scheme is as follows: for W after correctionjSorting, discarding the parameters corresponding to the minimum 2 weights, taking the rest parameters as evaluation indexes of the power grid,
scheme II: for W after correctionjAnd sequencing, taking the weight with the largest value as a reference, if the value of one or more weights is less than 5% of the largest weight, discarding the weight, and keeping all the weights which are not discarded as evaluation indexes of the power grid.
The invention has the following remarkable effects: (1) the method selects a plurality of specific indexes which have large influence on the operation of the power grid as evaluation basic indexes; (2) calculating the basic weight of each index through the correlation of the parameters; (3) by correcting the basic weight, the indexes can reflect the running state of the existing power grid to the greatest extent.
Detailed Description
A method for selecting an electric energy state evaluation index comprises the following steps:
the method comprises the following steps: sampling
The sampling parameters include: voltage deviation, frequency deviation, three-phase unbalance, harmonic ratio, voltage sag and line loss rate.
Wherein the content of the first and second substances,
voltage deviation: the difference between the actual voltage at each point and the nominal voltage of the system, expressed in percentage, i.e.
Figure BDA0002851813770000091
Wherein U is the actual voltage, UNIs a systemNominal voltage, Δ U, is the voltage deviation. The above formula is only a calculation formula of the voltage deviation, and when a plurality of groups of samples need to be taken, each voltage deviation is calculated by adopting the above formula. For three-phase voltages, the average of the three-phase voltages is taken as the actual voltage.
Frequency deviation: difference of actual frequency from nominal frequency, i.e.
Δf＝|f-fN|
Where f is the actual frequency, fNAt nominal frequency, Δ f is the voltage deviation. The above formula is only a calculation formula of the frequency deviation, and when a plurality of groups of samples need to be performed, each frequency deviation is calculated by adopting the above formula.
Three-phase unbalance: is the degree of inconsistency of three-phase voltage amplitudes in the power system, i.e.
Figure BDA0002851813770000101
Wherein max represents taking the maximum value, min represents taking the minimum value,
Figure BDA0002851813770000102
UA，UB，UCthe effective value of the three-phase voltage.
Harmonic ratio: the ratio of the harmonics to the total. The ratio of the sum of the harmonics within 10 to the fundamental wave is taken. Namely, it is
Figure BDA0002851813770000103
Wherein R represents the harmonic ratio, UHarmonic ofRepresenting the ith harmonic of U. For the case of multiple sampling, the harmonic calculation within 10 times is carried out on the U obtained by each sampling, and the harmonic ratio is calculated by using the formula according to the calculation result. For three-phase power, respective harmonic ratio is calculated respectively, and then the harmonic ratios of the three-phase power are averaged to be used as total harmonicWave fraction value. For the condition of multi-time sampling of three-phase electricity, when sampling is carried out at a certain time point, the three-phase electricity is respectively sampled, harmonic ratio is respectively calculated, then the harmonic ratio of the three-phase electricity is averaged to be used as a total harmonic ratio numerical value sampled at the time point, sampling of all time points is sequentially completed, and harmonic ratio sample data of all time points are obtained.
Voltage sag: the effective value of the supply voltage drops rapidly to 90% -10% of the rated value. The sampling content of the application comprises the voltage value and the duration of the voltage sag. The sampling includes amplitude reduction UDescendAnd duration tDescendThe product of the two is used as the final sampling value of the item. For three-phase power, if the voltage sag condition does not occur in all three phases at the same sampling time point, the parameter is recorded as 0, and if the voltage sag occurs, the product of the amplitude of each voltage sag and the time is firstly taken as the parameter of the current sampling, and then the product value is maximum.
Line loss rate: line loss is the energy loss resulting from the transmission of electrical energy through a transmission line. The ratio of line loss is the line loss ratio, i.e.
Line loss rate (power supply amount-electricity selling amount)/electricity purchasing amount x 100%
The sampling time of the sampling is 20 seconds to 40 seconds, and preferably 30 seconds; the sampling frequency is 10 times to 1000 times of the power grid frequency, preferably 300 times; the interval time ranges from 30 seconds to 10 minutes, preferably 1 minute; the total sampling time is 1-24 hours, and the sampling is carried out for at least 10 times.
Step two: data normalization
All the data are processed by adopting a unified normalization formula, and any existing normalization formula can be selected specifically, so that the application provides the simplest normalization formula, and the following steps are provided:
Figure BDA0002851813770000111
the normalized data retains only the three bits of data after the decimal point.
Forming a normalized data matrix after normalization
Figure BDA0002851813770000112
The rows represent different sampling time points, and the columns represent different data, specifically, a first column represents voltage deviation, a second column represents frequency deviation, a third column represents three-phase unbalance, a fourth column represents harmonic proportion, a fifth column represents voltage sag, and a sixth column represents line loss rate. So n in this application is 6.
Step three: calculating a compensation value
Step 3.1: mean value
Taking the average value of each line of data, namely calculating each line of data by adopting the following formula
Figure BDA0002851813770000121
Wherein m is the number of rows of the matrix B in step two, j represents the number of columns, i.e. the calculation is performed for the jth column, and the value range of j is 1 to n, where n is 6.
B is obtained by the above calculation1 are all、b2 are all、b3 are all、b4 are all、b5 are all、b6 are allSetting 6 weight correction values k1 are all、k2 are all、k3 are all、k4 are all、k5 are all、k6 are allThe 6 weight correction values correspond to the 6 parameters, and the specific numerical values of the 6 weight correction values are determined according to the following principle.
Anchor point
Figure BDA0002851813770000122
If it is
Figure BDA0002851813770000123
Then let kj all are＝0；
If it is
Figure BDA0002851813770000124
Then let kj all are＝0.5；
If it is
Figure BDA0002851813770000125
Then let kj all are＝1。
Step 3.2: median number
Taking the median of each line of data, if the line of data is odd, directly taking the median, and if the line of data is even, taking the mean value of the two numbers at the middle as the median.
B is obtained by the above calculation1 in、bIn 2 (2)、b3 in、b4 in、b5 in、b6 inSetting 6 weight correction values k1 in、kIn 2 (2)、k3 in、k4 in、k5 in、k6 inThe 6 weight correction values correspond to the 6 parameters, and the specific numerical values of the 6 weight correction values are determined according to the following principle.
Anchor point
Figure BDA0002851813770000131
If it is
Figure BDA0002851813770000132
Then let kj in＝0；
If it is
Figure BDA0002851813770000133
Then let kj in＝0.5；
If it is
Figure BDA0002851813770000134
Then let kj in＝1。
Step 3.3: variance (variance)
Taking variance for each column of data, namely calculating the variance for each column of data by adopting the following formula
Figure BDA0002851813770000135
Wherein m is the number of rows of the matrix B in step two, j represents the number of columns, i.e. the calculation is performed for the jth column, and the value range of j is 1-n, where n is 6.
Figure BDA0002851813770000136
B is obtained by the above calculation1 Square、b2 Square、b3 Square、b4-square、b5 Square、b6 SquareSetting 6 weight correction values k1 Square、k2 Square、k3 Square、k4-square、k5 Square、k6 SquareThe 6 weight correction values correspond to the 6 parameters, and the specific numerical values of the 6 weight correction values are determined according to the following principle.
Anchor point
Figure BDA0002851813770000137
If it is
Figure BDA0002851813770000138
Then let kSquare j＝0；
If it is
Figure BDA0002851813770000139
Then let kSquare j＝0.5；
If it is
Figure BDA0002851813770000141
Then let kSquare j＝1。
Step four: calculating weights
Order to
Figure BDA0002851813770000142
When all p areijAfter the calculation, E is calculated by the following formulaj
Figure BDA0002851813770000143
Where ln () represents the logarithm with the base constant e, and m is the number of rows of the matrix B in step two.
If p isijWhen the value is equal to 0, then order Ej＝0。
Weight WjIs calculated by the following formula
Figure BDA0002851813770000144
Step five: weight revision
Weight value WjAverage value of (2)
Figure BDA0002851813770000145
Figure BDA0002851813770000146
If k isj all areWhen the value is 0, then WjThe value of (d) is unchanged;
if k isj all areIf 0.5, the corrected weight is set to
Figure BDA0002851813770000147
If k isj all areIf 1, let the corrected weight be
Figure BDA0002851813770000148
If k isj inWhen the value is 0, then WjThe value of (d) is unchanged;
if k isj inIf 0.5, let the corrected weightIs composed of
Figure BDA0002851813770000149
If k isj inIf 1, let the corrected weight be
Figure BDA00028518137700001410
If k isSquare jWhen the value is 0, then WjThe value of (d) is unchanged;
if k isSquare jIf 0.5, the corrected weight is set to
Figure BDA0002851813770000151
If k isSquare jIf 1, let the corrected weight be
Figure BDA0002851813770000152
For example, if k is a parameter of a certain columnj all are＝kj in＝kSquare j1, then the weight of the parameter in the row is modified to
Figure BDA0002851813770000153
Step six: parameter selection
According to the corrected weight value WjAnd selecting parameters.
The selection of the parameters can be performed according to actual conditions, two specific selection schemes are provided in the application, and one of the two specific selection schemes can be arbitrarily selected by a person skilled in the art, and other strategies can be adopted for selection according to actual conditions.
The first scheme is as follows: for W after correctionjAnd sorting, discarding the parameters corresponding to the minimum 2 weights, and taking the rest parameters as evaluation indexes of the power grid.
Scheme II: for W after correctionjSorting is carried out, the weight with the largest value is taken as a reference, if the value of one or more weight is less than 5 percent of the largest weight, the weight is abandoned, and the weight which is not abandoned is all kept to be used as the referenceThe method is an evaluation index of the power grid.
When the method is used, the method is carried out once every a period of time as required, and the weight value of each index in the power grid is re-determined so as to adjust the evaluation mode of the power grid at any time. Because the power utilization characteristics of the power grid change rapidly in different time periods, the adjustment of the index weight is recommended to be performed once per week, and of course, a person skilled in the art can adjust the sampling interval period according to actual conditions, and the adjustment can be selected from one month, one quarter and half a year.

Claims (9)

1. A method for selecting an electric energy state evaluation index is characterized by comprising the following steps:
the method comprises the following steps: sampling
Sampling basic parameters;
step two: data normalization
Carrying out data normalization on the sampling parameters;
step three: calculating a compensation value
Calculating three compensation values;
step four: calculating weights
Calculating the weights of different parameters;
step five: weight revision
Revising the weight;
step six: parameter selection
According to the corrected weight value WjAnd selecting parameters.
2. The method according to claim 1, wherein the method comprises: the sampling parameters in the first step comprise: voltage deviation, frequency deviation, three-phase unbalance, harmonic ratio, voltage sag, line loss rate,
wherein the content of the first and second substances,
voltage deviation: the difference between the actual voltage at each point and the nominal voltage of the system, expressed in percentage, i.e.
Figure FDA0002851813760000011
Wherein U is the actual voltage, UNThe system nominal voltage is adopted, the delta U is the voltage deviation, the formula is only a calculation formula of the voltage deviation, when a plurality of groups of sampling are needed, each voltage deviation is calculated by adopting the formula, for the three-phase voltage, the average value of the three-phase voltage is taken as the actual voltage,
frequency deviation: difference of actual frequency from nominal frequency, i.e.
Δf＝|f-fN|
Where f is the actual frequency, fNFor the nominal frequency, Δ f is the voltage deviation, the above formula is only the calculation formula of the frequency deviation, when a plurality of sets of sampling are required, each frequency deviation is calculated by the above formula,
three-phase unbalance: is the degree of inconsistency of three-phase voltage amplitudes in the power system, i.e.
Figure FDA0002851813760000021
Wherein max represents taking the maximum value, min represents taking the minimum value,
Figure FDA0002851813760000022
UA，UB，UCis an effective value of the three-phase voltage,
harmonic ratio: the ratio of harmonic to total amount is taken as the ratio of the sum of harmonics within 10 to fundamental wave, i.e. the ratio
Figure FDA0002851813760000023
Wherein R represents the harmonic ratio, UHarmonic ofRepresents the ith harmonic of U, and for the case of multiple sampling, the harmonic calculation within 10 times is performed on the U obtained by each samplingCalculating harmonic ratio according to the formula, calculating respective harmonic ratio for three-phase power, averaging the harmonic ratios of the three-phase power to obtain total harmonic ratio, sampling the three-phase power at a certain time point for multiple sampling, calculating harmonic ratios, averaging the harmonic ratios of the three-phase power to obtain total harmonic ratio, sequentially sampling at all time points to obtain harmonic ratio sample data at all time points,
voltage sag: the effective value of the power supply voltage is rapidly reduced to 90% -10% of the rated value, the sampling content of the method comprises the voltage value and the duration of voltage sag, and the sampling comprises amplitude reduction UDescendAnd duration tDescendTaking the product of the two as the final sampling value of the project, recording the parameter as 0 if the three phases do not have voltage sag at the same sampling time point for the three-phase power, if the voltage sag occurs, firstly taking the product of the decreasing amplitude of each voltage sag and the time, and then taking the maximum value of the product as the parameter of the current sampling,
line loss rate: line loss is the energy loss generated by the transmission of electric energy through a transmission line, and the ratio of the line loss is the line loss rate, namely
The line loss rate is (power supply amount-electricity sales amount)/electricity purchase amount × 100%.
3. The method according to claim 2, wherein the method comprises: the sampling time of the sampling in the step one is 20 seconds to 40 seconds; the sampling frequency is 10-1000 times of the power grid frequency; the interval time ranges from 30 seconds to 10 minutes; the total time of sampling is 1-24 hours.
4. The method according to claim 3, wherein the method comprises: the sampling time in the step one is preferably 30 seconds; the sampling frequency is preferably 300 times; the interval time is preferably 1 minute; the total sampling time ensures a minimum of 10 samples.
5. The method according to claim 4, wherein the method comprises: the second step comprises the normalization by the following formula,
Figure FDA0002851813760000041
the normalized data retains only the three bits of data after the decimal point,
forming a normalized data matrix after normalization
Figure FDA0002851813760000042
The rows represent different sampling time points, and the columns represent different data, specifically, the first column represents voltage deviation, the second column represents frequency deviation, the third column represents three-phase imbalance, the fourth column represents harmonic proportion, the fifth column represents voltage sag, and the sixth column represents line loss rate, so that n in the present application is 6.
6. The method according to claim 5, wherein the method comprises: the third step comprises the steps of,
step 3.1: mean value
Taking the average value of each line of data, namely calculating each line of data by adopting the following formula
Figure FDA0002851813760000043
Where m is the number of rows in the matrix B in step two, j represents the number of columns, i.e. the calculation is performed for the jth column, j has a value in the range of 1 to n, where n is 6,
b is obtained by the above calculation1 are all、b2 are all、b3 are all、b4 are all、b5 are all、b6 are allSetting 6 weight correction values k1 are all、k2 are all、k3 are all、k4 are all、k5 are all、k6 are allThe 6 weight correction values correspond to 6 parameters, and the specific numerical values of the 6 weight correction values are determined according to the following principle,
anchor point
Figure FDA0002851813760000044
If it is
Figure FDA0002851813760000051
Then let kj all are＝0；
If it is
Figure FDA0002851813760000052
Then let kj all are＝0.5；
If it is
Figure FDA0002851813760000053
Then let kj all are＝1，
Step 3.2: median number
Taking the median of each row of data, if the row of data is odd, directly taking the median, if the row of data is even, taking the mean value of the two numbers at the middle as the median,
b is obtained by the above calculation1 in、bIn 2 (2)、b3 in、b4 in、b5 in、b6 inSetting 6 weight correction values k1 in、kIn 2 (2)、k3 in、k4 in、k5 in、k6 inThe 6 weight correction values correspond to 6 parameters, and the specific numerical values of the 6 weight correction values are determined according to the following principle,
anchor point
Figure FDA0002851813760000054
If it is
Figure FDA0002851813760000055
Then let kj in＝0；
If it is
Figure FDA0002851813760000056
Then let kj in＝0.5；
If it is
Figure FDA0002851813760000057
Then let kj in＝1，
Step 3.3: variance (variance)
Taking variance for each column of data, namely calculating the variance for each column of data by adopting the following formula
Figure FDA0002851813760000058
Where m is the number of rows in the matrix B in step two, j represents the number of columns, i.e. the calculation is performed for the jth column, j has a value in the range 1-n, where n is 6,
Figure FDA0002851813760000061
b is obtained by the above calculation1 Square、b2 Square、b3 Square、b4-square、b5 Square、b6 SquareSetting 6 weight correction values k1 Square、k2 Square、k3 Square、k4-square、k5 Square、k6 SquareThe 6 weight correction values correspond to 6 parameters, and the specific numerical values of the 6 weight correction values are determined according to the following principle,
anchor point
Figure FDA0002851813760000062
If it is
Figure FDA0002851813760000063
Then let kSquare j＝0；
If it is
Figure FDA0002851813760000064
Then let kSquare j＝0.5；
If it is
Figure FDA0002851813760000065
Then let kSquare j＝1。
7. The method according to claim 6, wherein the method comprises: the fourth step comprises the steps of,
order to
Figure FDA0002851813760000066
When all p areijAfter the calculation, E is calculated by the following formulaj
Figure FDA0002851813760000067
Where ln () represents the logarithm with the base constant e, m is the number of rows of the matrix B in step two,
if p isijWhen the value is equal to 0, then order Ei＝0，
Weight WjIs calculated by the following formula
Figure FDA0002851813760000071
8. The method according to claim 7, wherein the method comprises: the fifth step comprises the steps of,
weight value WjAverage value of (2)
Figure FDA0002851813760000072
Figure FDA0002851813760000073
If k isj all areWhen the value is 0, then WjThe value of (d) is unchanged;
if k isj all areIf 0.5, the corrected weight is set to
Figure FDA0002851813760000074
If k isj all areIf 1, let the corrected weight be
Figure FDA0002851813760000075
If k isj inWhen the value is 0, then WjThe value of (d) is unchanged;
if k isj inIf 0.5, the corrected weight is set to
Figure FDA0002851813760000076
If k isj inIf 1, let the corrected weight be
Figure FDA0002851813760000077
If k isSquare jWhen the value is 0, then WjThe value of (d) is unchanged;
if k isSquare jIf 0.5, the corrected weight is set to
Figure FDA0002851813760000078
If k isSquare jWhen 1, then orderThe corrected weight value is
Figure FDA0002851813760000079
9. The method according to claim 8, wherein the method comprises: step six includes one of the following two optional schemes,
the first scheme is as follows: for W after correctionjSorting, discarding the parameters corresponding to the minimum 2 weights, taking the rest parameters as evaluation indexes of the power grid,
scheme II: for W after correctionjAnd sequencing, taking the weight with the largest value as a reference, if the value of one or more weights is less than 5% of the largest weight, discarding the weight, and keeping all the weights which are not discarded as evaluation indexes of the power grid.
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