CN107863770B - A method for judging the cause of abnormal line loss rate in low-voltage station area - Google Patents

Abstract

A method for judging the cause of abnormal line loss rate in a low-voltage station area belongs to the field of measurement. It first determines the definition standard of abnormal line loss rate relative to the unreasonable or non-abnormal line loss rate; then constructs an efficient judgment process based on different data representations of abnormal line loss rate caused by different factors, and analyzes and corrects the line loss caused by various factors. An abnormal loss rate analysis method is obtained, which can determine the composite cause. It can be widely used in the field of power supply operation and line loss management in low-voltage station area.

Description

A method for judging the cause of abnormal line loss rate in low-voltage station area

technical field

The invention belongs to the field of measurement, and in particular relates to a method for judging the cause of abnormal line loss rate in a low-voltage station area.

Background technique

The premise of the refinement of line loss to guide energy saving and consumption reduction is that the obtained statistical value of line loss rate is true and reliable. However, in practical application, it is found that the line loss rate of low-voltage station area obtained by the method of comparing electricity supply and sales often appears abnormal (negative value, abnormally high value). Taking a power supply company as an example in a month in 2015, the stations with a line loss rate of 0-10% accounted for about 50% of the stations, and more than 10% of the remaining stations had negative line loss rates and more than 4% of stations. The line loss rate exceeds 50%. The abnormal line loss rate makes the line loss rate statistics lose the guiding significance of energy saving and loss reduction.

Therefore, the identification of abnormal line loss rate and the possible causes of abnormal line loss rate have become important issues that must be solved in line loss management.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for judging the cause of abnormal line loss rate in a low-voltage station area. It first determines the definition standard of abnormal line loss rate relative to the unreasonable (non-abnormal) line loss rate, and then constructs an efficient judgment process based on different data representations of abnormal line loss rate caused by different factors, and analyzes and corrects various factors. The line loss rate is abnormal, and an abnormal line loss rate analysis method that can determine the composite cause is obtained.

The technical scheme of the present invention is to provide a method for judging the cause of abnormal line loss rate in a low-voltage station area, which is characterized by:

First, determine the definition standard of abnormal line loss rate relative to unreasonable or non-abnormal line loss rate;

Then, according to different data representations of abnormal line loss rate caused by different factors, an efficient judgment process is constructed, and the abnormal line loss rate caused by various factors is analyzed and corrected;

Furthermore, an abnormal analysis method of line loss rate that can determine the composite causes is obtained.

Specifically, when determining the criterion for the abnormal line loss rate relative to the unreasonable or non-abnormal line loss rate, there are two thresholds for the abnormal line loss rate determination in the station area: one is between a reasonably high line loss rate and an abnormally high line loss rate. The threshold is called the upper threshold; the other is the threshold between the reasonably low line loss rate and the abnormally low line loss rate, called the lower threshold.

Further, the lower threshold is set to 0%, and when the upper threshold is set, the problems of three-phase load unbalance and insufficient reactive power compensation need to be considered.

Specifically, the determination method includes the determination of technical problems and line loss correction, the identification of three-phase load imbalance and line loss correction, the identification of insufficient reactive power compensation and line loss correction, and the determination of management problems and line loss correction. Correction, identification and line loss correction of unmatched household change information, identification and line loss correction of unmatched CT ratio of gateway meter, identification and line loss correction of low success rate of centralized copying, identification and line loss correction of serious electricity theft problem .

The judging method described in the technical solution of the present invention proposes a method for identifying the cause of abnormal line loss rate of composite type, which can identify and correct abnormal line loss rate caused by various reasons including technical and management.

Compared with the prior art, the advantages of the present invention are:

The technical scheme of the present invention firstly determines the definition standard of abnormal line loss rate relative to unreasonable (non-abnormal) line loss rate, and then constructs an efficient judgment process according to different data representations of abnormal line loss rate caused by different factors, and analyzes and corrects each The abnormal line loss rate caused by various factors is obtained, and an abnormal line loss rate analysis method that can determine the composite cause is obtained.

Description of drawings

Fig. 1 is a schematic diagram of the general flow of the identification of the abnormal cause of the line loss rate of the present invention;

Fig. 2 is a schematic diagram of the judgment flow of the management problem in the abnormal analysis of the line loss rate of the present invention;

3 is a schematic diagram of a wrong wiring identification process flow diagram of the gateway table of the present invention;

Figures 4-1 to 4-5 are schematic diagrams of several appearances of abnormal line loss rate.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings.

The technical scheme of the present invention provides a method for judging the abnormal cause of the line loss rate in the low-voltage station area, and its invention lies in:

First, determine the definition standard of abnormal line loss rate relative to unreasonable or non-abnormal line loss rate;

Then, according to different data representations of abnormal line loss rate caused by different factors, an efficient judgment process is constructed, and the abnormal line loss rate caused by various factors is analyzed and corrected;

Furthermore, an abnormal analysis method of line loss rate that can determine the composite causes is obtained.

1. Definition of non-abnormal upper bound of line loss rate in Taiwan area

The abnormal line loss rate in the station area refers to the distortion of the line loss rate, that is, the statistical value of the line loss rate deviates from the actual technical line loss in the station area. For this reason, the reasons for the abnormal line loss rate mainly include:

(1) Wrong connection of the gateway meter: In this case, the power supply will be undercounted, and the line loss rate will be negative;

(2) The success rate of centralized copying is low: In this case, the electricity sales will be undercounted, and the line loss rate will be high;

(3) Mismatch of variable-household information: In this case, among the associated stations, one station has less electricity sales and the corresponding line loss rate is higher than the actual value, while the other station area has more electricity sales and lower line loss rate. to the actual value;

(4) The CT transformation ratio of the gateway table is wrong: if the actual CT transformation ratio is higher than the transformation ratio used in the calculation of the original power supply, the original power supply will be undercounted, which will lead to the statistical value of the line loss rate being close to 0 or negative; otherwise, Then the statistical value of the line loss rate in the station area is an abnormally high value;

(5) Serious electricity theft problem: In this case, the electricity sold is undercounted, resulting in a high line loss rate.

It is worth noting that the above management issues (1) to (4) are not included in the evaluation of the reasonable range of the line loss rate in the station area; and in the abnormal range of the line loss rate in the station area, the three-phase area in the station area is not considered. The problem of high line loss rate caused by unbalance and insufficient reactive power compensation, because the high line loss rate caused by these two factors is a high value that reflects the true level of the technical line loss rate, not an abnormal value (distortion value).

In view of the above considerations, the abnormal determination threshold of the line loss rate in the station area should be the limit value that the actual technical line loss rate in the station area may reach without taking into account the management problems of (1) to (4) above. It is noted that there are two thresholds for the abnormal judgment of the line loss rate in the Taiwan area: one is the threshold between a reasonably high line loss rate and an abnormally high line loss rate, which is called the upper threshold; the other is a reasonable low line loss rate-abnormally low line loss. The threshold between the rates is called the lower threshold. The lower threshold can be set to 0%, which is the lower bound level of the line loss rate that will not be reached even when the transformer is no-load; and the setting of the upper threshold needs further analysis.

Calculation of the Upper Threshold for Abnormal Judgment of Line Loss Rate in Taiwan Area

In the evaluation of the reasonable range of the line loss rate, the reasonable differences in factors such as the length of the main line in the Taiwan area, the load distribution, and the actual load rate of the transformer have been fully taken into account. For this reason, when setting the non-abnormal upper threshold, the main consideration is the unbalance of three-phase load and insufficient reactive power compensation. According to the statistical results of a certain area, only about 13% of the three-phase load imbalance in the low-voltage station area can achieve ≤15%, and the problem of three-phase load imbalance is more serious; In terms of power factor, the power factor of more than 99.98% of the stations is greater than or equal to 0.85. Therefore, when calculating the non-abnormal upper threshold of online loss rate, the measurement standards for abnormal and non-abnormal of these two factors are different. Specifically:

(1) Influence of three-phase load unbalance degree: The three-phase current unbalance degree required by the power industry specification is ≤ 0.15 as the constraint, and the corresponding phase unbalance coefficient is (1.08, 0, 0.92), and the line loss rate in the station area is at this time. Compared with the three-phase equilibrium situation, the increase is at most 2.6773 times. In the calculation of the non-abnormal upper bound value, the most serious situation of the three-phase load unbalance is considered. At this time, the phase unbalance coefficients β _A , β _B , and β _C are (2, -1, -1). The loss rate is up to 6 times higher than the three-phase equilibrium.

(2) Insufficient reactive power compensation: still take the power factor at the gateway meter ≥ 0.85 as the standard, it is normal to meet this standard, otherwise it is abnormal.

According to the above standards, the abnormal criteria of line loss rate in various station areas are calculated as shown in the following table.

Table 1 Criteria for abnormal line loss rate in Taiwan area

Abnormal appearance of line loss rate in Taiwan area

Figure 4-1 is a schematic diagram of the line loss rate continuously being zero, Figure 4-2 is a schematic diagram of a stable and excessive line loss rate, Figure 4-3 is a schematic diagram of a stable and negative line loss rate, and Figure 4-4 is a schematic diagram of the line loss rate Schematic diagram of the abnormal rate for a few months occasionally. Figure 4-5 is a schematic diagram of the line loss rate fluctuating high and low.

Specifically, as shown in Figure 4-1 to Figure 4-5, the appearance of abnormal line loss rate in the station area includes the following:

(1) The line loss rate is zero: the line loss rate for the whole year or some months is zero. Set according to the line loss refinement platform program, when the power supply is zero, the line loss rate is set to zero. Therefore, this kind of abnormality is mostly caused by the abnormal wiring of the gateway meter, which causes the measured power supply to be zero.

(2) The line loss rate is stable and too large: the line loss rate in the Taiwan area usually exceeds 50% continuously, or even reaches 100%. Excessive line loss rate often corresponds to certain management problems (such as a large user's change-user mismatch).

(3) The line loss rate is stable and negative: the line loss rate is persistently negative, which is usually caused by some technical (such as incorrect wiring of the gateway meter) or management (such as the mismatch of the change-user information of a large user). .

(4) Line loss rate fluctuated high and low: The line loss rate in Taiwan area fluctuated high and low, even positive and negative. This kind of abnormal line loss rate is the result of the combined action of many reasons, which is very common.

Possible reasons for abnormal line loss rate in Taiwan area:

The reasons for the abnormal line loss rate include technical and management problems. The table in Table 2 sorts out the data representations corresponding to various abnormal causes and their approximate judgment basis. in:

(1) The technical reason for the abnormal line loss rate in the Taiwan area is mainly due to the abnormal wiring of the gateway meter, and the high line loss rate caused by factors such as unbalanced three-phase load and insufficient reactive power compensation is an unreasonable line loss rate problem (but the line loss rate is unreasonable). The loss rate can still reflect the true level of line loss in the station area, which is not a distortion). The abnormal connection of the gateway meter is divided into three categories: loss of voltage or loss of current, reverse connection of the inlet and outlet of the current transformer, and wrong connection between phases, among which:

a) Loss of voltage or loss of current: It is often caused by poor connection at the wiring (such as loose screws, etc.), and the measured value of one-phase or several-phase voltage/current is zero;

b) The inlet and outlet of the current transformer are reversely connected: the current of one or several phases is negative;

c) Interphase misconnection: including two-phase misconnection and three-phase misconnection. Two-phase wrong wiring, such as A phase is wrongly connected to B-phase, B-phase is wrongly connected to A-phase, and three-phase wrong-wiring includes three-phase forward wrong wiring (such as A-phase to B-phase, B-phase to C-phase, C-phase to wrong-connection). Phase A is connected to phase A) and three-phase reverse wiring (such as phase A is connected to phase C, phase C is connected to phase B, and phase B is connected to phase A).

(2) There are many management problems that lead to abnormal line loss rate in Taiwan area, including:

a) The transformation ratio information of the current transformer of the gateway meter does not match: in this case, the line loss rate in the station area is a continuous negative value (when the actual CT transformation ratio is greater than the CT transformation ratio used in the calculation) or a continuous high value (when the actual CT transformation ratio) The CT transformation ratio is smaller than the CT transformation ratio used in the calculation).

b) Information mismatch between large users and households: This situation usually occurs between two stations corresponding to the same substation, where the line loss rate of one station area is continuously high, and the line loss rate of the other station area is at the same time. Continuously low value (close to zero)/negative value, and there is a certain inverse correlation between the line loss rates of the two stations, that is, the so-called trade-off.

c) Low success rate of centralized copying: A low success rate of centralized copying will lead to a high line loss rate in the current month.

d) There is a serious problem of electricity stealing in the station area: In this case, the line loss rate in the station area is high, but because the electricity stealing is staged (for example, electricity stealing is more serious in summer), the line loss in the station area is not necessarily continuous. high value.

Table 2 Technical reasons for abnormal line loss rate in Taiwan area

2. Judgment method of abnormal composite causes of line loss rate

Aiming at the fact that the abnormal line loss rate is often caused by a composite cause, the technical solution proposes an abnormal line loss rate analysis method that can determine the composite cause.

Judgment process:

The overall process of identifying the cause of abnormal line loss rate is shown in Figure 1 and Figure 2. In order to identify the compound causes of abnormal line loss rate, the following considerations are included in the flow chart:

(1) The identification of technical reasons such as serious three-phase imbalance and insufficient reactive power compensation is not excluded. Although the unbalanced three-phase load and insufficient reactive power compensation cause abnormal line loss rate (distortion) problems, the existence of these problems will cause the statistical value of the line loss rate in the station area to deviate from the reasonable range, and the identification process can be used to identify the station area. The line loss rate is corrected to a reasonable range as the termination condition. Therefore, the identification of these two technical problems and the corresponding correction of the line loss rate (that is, to obtain the possible value of the line loss rate in the station area if these two problems do not exist) are also included in the identification process.

(2) The identification of technical problems precedes the identification of management problems, because technical problems can be judged more accurately based on the measured values; and in the identification of technical problems, the wiring errors of the gateway meter are identified first, which is the gateway meter Wiring errors will affect the statistical values of the three-phase unbalance degree and power factor. It is meaningful to carry out the analysis of the latter two after correcting the three-phase unbalance degree and power factor values according to the connection problem of the gateway meter.

(3) After analyzing and judging that there is a certain type of problem in each step, the statistical value of the line loss rate needs to be corrected for this type of problem, and then the subsequent problem determination is continued based on the corrected line loss rate. In addition, in the analysis of technical problems, it is not possible to skip certain steps based on whether the current line loss rate exceeds the upper bound of the reasonable range or is lower than the lower bound of the reasonable range (such as crossing the three-phase load imbalance for the station area with negative line loss rate). degree analysis), which takes into account that there may be two types of problems that will reduce and increase the line loss rate at the same time in the station area.

(4) In the management problem, if the statistical value of the line loss rate in the station area is higher than the lower bound of the reasonable range, it is mostly because the CT transformation ratio is too low (need to try to increase the transformation ratio) or the change of household does not match the problem; on the contrary, if the station area line The more reasonable the upper bound of the loss rate statistic is, there are three possibilities: the CT ratio is too high, the household change does not match, and there is a serious electricity stealing problem. If the line loss rate cannot be within a reasonable range after eliminating the above problems, it can be determined that the station area structure (for example, the actual line length is far beyond the reasonable range).

Judgment of technical problems and correction method of line damage:

The technical problems involved in Figure 3 include three aspects: wrong gateway meter wiring, unbalanced three-phase load, and insufficient reactive power compensation (cos<0.85).

Identification of wrong wiring of gateway table and correction of line loss:

Figure 3 shows the process and criteria for the judgment of incorrect wiring of the gateway table. Among them, the line loss correction in the case of various wiring errors is implemented as follows:

(1) One-phase loss of pressure or loss of current:

When one phase loses voltage or current, the voltage or current of one phase is zero, and the measured active power is:

The active power under normal conditions is

The line loss correction factor is

Multiply the statistical value of line loss in the station area by the line loss correction coefficient to obtain the corrected line loss in the station area (the same below).

The reactive power measured in the case of one-phase loss of voltage or current is

The power factor does not require correction.

(2) Two-phase loss of pressure or loss of current:

When two phases lose voltage or current, the voltage or current of two phases is zero, and the measured active power is

The line loss correction factor is

The reactive power measured at this time is

The power factor also needs no correction.

(3) Three-phase voltage loss or current loss:

When the three-phase voltage or current is lost, the measured active power is zero. In the case of three-phase current loss, the statistical values of power supply and line loss rate in the platform area are all zero; while for the three-phase voltage loss situation, considering that the three-phase voltage is always near the rated voltage, it can be estimated that the line loss of the corresponding platform area is:

据统计为96.93。In the above formula, U _ph,N is the rated value of the phase voltage, that is, 0.22kV; E _s is the monthly electricity sales of the corresponding station area; since there is no measurement data for the reactive power when the three-phase current is lost, the power factor of the station area cannot be calculated. When correcting the line loss, only the average value of the power factor at the gateway side of the low-voltage station area can be taken.

According to statistics, it is 96.93.

(4) Current transformers are connected in one phase:

The active power measured when one phase is connected is

The line loss correction factor is

The reactive power measured at this time is

The power factor does not need to be corrected.

(5) The current transformer is connected in two phases:

The active power measured when the two phases are connected is

The line loss correction factor is

The reactive power measured at this time is

The power factor also does not need to be corrected.

(6) The three-phase connection of the current transformer:

The active power measured when the three-phase connection is

The line loss correction factor is

The reactive power measured at this time is

The power factor also does not need to be corrected.

(7) The case where the two phases of the current transformer are wrongly wired:

When the two phases of the current transformer are wrongly wired, the measured active power is

At this time, the statistical value of the power supply is zero, and then the statistical value of the line loss rate is zero. Since the statistic value of reactive power is also zero, the actual power factor cannot be known, so the formula in (3) can be used to estimate the line loss in the station area.

(8) The three-phase wrong wiring of the current transformer:

For the case where the three-phase forward is wrongly wired, the active power measured at this time is

The line loss correction factor is

The reactive power measured at this time is

The actual power factor angle is

The actual power factor is

为台区关口侧功率因数的表计量测值。In the above formula,

It is the metered value of the power factor at the gateway side of the station area.

For the case of three-phase reverse wiring, the measured power supply at this time is

The line loss correction factor is

The reactive power measured at this time is

The actual power factor angle is

The actual power factor is

同样为台区关口侧功率因数的表计量测值。in,

It is also the metered value of the power factor at the gateway side of the station area.

Three-phase load unbalance identification and line loss correction method:

According to the three-phase current data measured by the gateway meter, the three-phase load unbalance degree can be calculated as follows:

Among them, I _max and I _min respectively represent the maximum value and the minimum value in the three-phase current. In this project, the three-phase current at different times of three days is used for the gateway meter in the station area with abnormal line loss rate, and the above-mentioned unbalance degree indicators are calculated separately. If the average value of the three unbalance degree indicators is greater than 15%, it is considered that there is a serious three-phase load. imbalance problem.

Because the line loss correction coefficient under three-phase unbalance is

Divide the measured line loss by the above coefficient to obtain the line loss level of the target station area under the assumption that the three-phase load is strictly balanced.

Identification of insufficient reactive power compensation and correction of line loss:

In this technical scheme, the power factor values at three different times on the side of the gateway for three days are collected in the station area with abnormal line loss rate. If the average value of the three values is less than 0.85, it is considered that the corresponding station area has the problem of insufficient reactive power compensation.

(0.85)时，损耗的修正系数为The measured value of the power factor at the gateway side in the station area

(0.85), the correction factor for loss is

Judgment of management problems and line loss correction methods:

Management problems that may cause abnormal line loss rate in the station area include mismatch of large user change account information, mismatch of CT transformation ratio of gateway meter, low success rate of centralized copying, and serious power theft.

Identification and line loss correction methods for mismatched account information:

Household change mismatch mainly occurs in the station area corresponding to the two transformers at the same station, and such station area is called the relevant station area. Household change matching analysis is only carried out on the relevant station area. Traditionally, the inspection of household change mismatch needs to be carried out by manual on-site inspection or relying on the station area identifier. This project proposes a covariance analysis method for the line loss rate of the relevant station area to find out the stations with mismatched household changes through data analysis. Area. The specific method is: collect the line loss rate of the relevant station area (denoted as station area i and station area j) for a year and 12 months.

为台区i全年月线损率 均值。当协方差小于零则意味着两个台区的线损率此消彼长，符合变户不匹配的特 点。值得注意的是，上述方法适用于信息关联错误的用户为用电量很大的用户，这 也是变户不匹配分析中主要关心的问题。In the above formula, ΔE _i,m % represents the line loss rate of the m-th month in the meeting area i,

It is the average monthly loss rate of Taiwan district i in the whole year. When the covariance is less than zero, it means that the line loss rates of the two stations are changing, which is in line with the characteristics of household change mismatch. It is worth noting that the above method is suitable for users with incorrect information associations who consume a lot of electricity, which is also the main concern in the analysis of mismatched users.

After finding the two associated station areas that do not match the variable-user, by checking the operating capacity of the large user, you can find the account number of the large user whose information matches the wrong information. Let the electricity consumption of the user in the current month be E _c , then the line loss of the station area is as follows: Correction:

(1) For the station area of multi-meter electricity consumption E _c

ΔE _x =E ₀ ·ΔE _m %+E _c

(2) For stations with less electricity consumption E _c

ΔE _x =E ₀ ·ΔE _m %-E _c

In the above two formulas, ΔE _x represents the corrected line loss of the station area; E ₀ represents the monthly power supply of the station area; ΔE _m % is the actual measurement of the line loss rate of the station area in the current month.

The identification and line loss correction method of the CT ratio mismatch of the gateway table:

The CT transformation ratio used by the line loss refinement platform is the magnification in the EDCM system, and some of the problems in the PMS2.0 system are inconsistent. According to statistics, CT transformation ratios are 40, 60, 80, 100, 120, 160, 200, 240, 300, 320, 400, 500, 600, and 640. When the line loss rate in the station area meets the

or

When the CT ratio does not match the line loss rate correction measures for the corresponding station area. In the above formula, γ _CT and γ' _CT are the CT transformation ratio and the corrected CT transformation ratio used in the current EDCM system of the corresponding station area, respectively, where the corrected transformation ratio is obtained by trying the numerical sequence of CT transformation ratios.

Correspondingly, when the CT transformation ratio is corrected from γ _CT to γ' _CT , the monthly loss reduction in the station area is corrected as follows:

ΔE _x =E ₀ ·ΔE _m %-E ₀ ·(γ _CT -γ' _CT )

Identification and line loss correction methods with low success rate of centralized copying:

At present, the average success rate of centralized copying in low-voltage station areas can reach more than 90%. If the monthly centralized copying success rate of a low-voltage station area υ _RMS % < 90%, the low centralized copying success rate will be regarded as causing the line loss rate of the station area. one of the unusual factors.

Assuming that the success rate of centralized copying in this station area can be increased to 100%, the line loss in the station area can be corrected as follows

为目标台区当月平均每户用电量，当无法掌握具体台区的数据时， 也可按用电结构取值；n_c为目标台区的用户数。In the above formula,

is the monthly average electricity consumption of each household in the target station area. When the data of the specific station area cannot be grasped, the value can also be taken according to the power consumption structure; n _c is the number of users in the target station area.

Identification of serious electricity theft and line loss correction methods:

After all the above problems are corrected for line loss, if the line loss is still abnormal and too large, it is possible to consider implementing anti-power stealing user search. For this purpose, this project proposes a multi-dimensional outlier analysis method with traceability function, as shown in Section 5.3 .8 as described. After using this method to search out the user set C _s suspected of stealing electricity in the target station area in the current month, the loss reduction of the corresponding station area can be corrected by the following formula

In the above formula, χ% still represents the accuracy of the search method for suspicious users of electricity stealing; E _c,i represents the monthly electricity consumption of the ith suspicious user of electricity stealing in the user set C _s .

The technical scheme of the present invention firstly determines the definition standard of abnormal line loss rate relative to unreasonable (non-abnormal) line loss rate, and then constructs an efficient judgment process according to different data representations of abnormal line loss rate caused by different factors, and analyzes and corrects it. The abnormal line loss rate caused by various factors is obtained, and an abnormal line loss rate analysis method that can determine the composite cause is obtained.

The invention can be widely used in the fields of power supply operation and line loss management in low-voltage station areas.

Claims (5)

1. A method for judging the reason of the line loss rate abnormality of a low-voltage transformer area comprises the following steps of firstly determining a definition standard that the line loss rate abnormality is unreasonable or not abnormal relative to the line loss rate; then, constructing an efficient judging flow according to different data representations of the abnormal line loss rate caused by different factors, and analyzing and correcting the abnormal line loss rate caused by various factors; the method is characterized in that:

the method for judging the abnormal reason of the line loss rate of the low-voltage transformer area judges and corrects the line loss of the manageability problem after identifying the technical reason;

the managerial problems comprise the problems of unmatched large user subscriber information, unmatched CT transformation ratios of gateway tables, low centralized meter reading success rate and serious electricity stealing;

the method for judging the abnormal reason of the line loss rate of the low-voltage transformer area judges and corrects the line loss of the manageability problems according to the following steps:

step 1: judging that the line loss rate exceeds an upper threshold, if so, performing the step 2, and if not, turning to the step 4;

step 2: judging whether the line loss rate is qualified after the CT transformation ratio is reduced, if the line loss rate is qualified, performing the step 3, and if the line loss rate is unqualified, transferring to the step 5;

and step 3: correcting the line loss rate, and turning to the step 11;

and 4, step 4: judging whether the line loss rate is qualified after the CT transformation ratio is adjusted upwards, if so, performing the step 3, and if not, transferring to the step 10;

and 5: judging whether the problem of matching between users is existed or not, if so, performing the step 6, and if not, transferring to the step 7;

step 6: line loss rate correction is carried out, and if the line loss rate after correction is reasonable, the step is switched to step 11; if the line loss rate after correction is not reasonable, turning to step 7;

and 7: judging whether a serious electricity stealing problem exists or not, if so, performing a step 8, and if not, performing a step 9;

and 8: correcting the line loss rate; if the corrected line loss rate is reasonable, turning to the step 11; if the line loss rate after correction is not reasonable, turning to step 9;

and step 9: judging the abnormal structure of the transformer area, and turning to the step 11;

step 10: judging whether the problem of matching between users is existed or not, if so, performing the step 8, and if not, transferring to the step 9;

step 11: recording the searched problems and finishing the judgment;

when the matching of large user changing information is identified, a relevant station area line loss rate covariance analysis method is adopted, and a station area with a user-to-user mismatching is found out through data analysis;

when the CT transformation ratios of the gateway table are identified to be matched, line loss rate correction measure suggestions that the CT transformation ratios are not matched are made for corresponding distribution room areas;

when the serious electricity stealing problem is identified, a multi-dimensional outlier analysis method with a tracing function is adopted to search out a user set suspected of electricity stealing in the current month of the target transformer area.

2. The method for determining the cause of the line loss rate abnormality of the low-voltage distribution room as claimed in claim 1, wherein when determining the definition standard that the line loss rate abnormality is not reasonable or abnormal with respect to the line loss rate, the threshold for determining the line loss rate abnormality of the distribution room is two: one is a threshold between reasonable high loss rate-abnormal high loss rate, called upper threshold; the other is a threshold between reasonably low line loss rate-abnormally low line loss rate, called the lower threshold.

3. The method for determining the cause of the line loss rate abnormality of the low-voltage transformer area according to claim 1, wherein the lower threshold is set to 0%, and the upper threshold is set in consideration of the problems of the three-phase load unbalance degree and the insufficient reactive power compensation.

4. The method for determining the cause of the abnormal line loss rate of the low-voltage transformer area as claimed in claim 1, wherein the determination method comprises the steps of determining a technical problem and correcting the line loss, identifying unbalanced three-phase load and correcting the line loss, identifying insufficient reactive power compensation and correcting the line loss, identifying an administrative problem and correcting the line loss, identifying and correcting the unmatched subscriber information and line loss, identifying and correcting the unmatched CT transformation ratio of the gateway table and the unmatched line loss, identifying and correcting the line loss with low integration success rate and identifying and correcting the serious electricity stealing problem and correcting the line loss.

5. The method for determining the cause of the line loss rate abnormality of the low-voltage transformer area according to claim 1, wherein a composite method for identifying the cause of the line loss rate abnormality is provided, which can identify and correct the line loss rate abnormality caused by a plurality of causes including technical and managerial causes.

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