CN110927480B

CN110927480B - Low-voltage transformer area loss reduction method for HPLC application environment

Info

Publication number: CN110927480B
Application number: CN201911062471.4A
Authority: CN
Inventors: 韩跃峻; 张洋; 陆斌; 陈盛; 周璿; 黄潇贻
Original assignee: State Grid Shanghai Electric Power Co Ltd
Current assignee: State Grid Shanghai Electric Power Co Ltd
Priority date: 2019-11-02
Filing date: 2019-11-02
Publication date: 2022-06-21
Anticipated expiration: 2039-11-02
Also published as: CN110927480A

Abstract

A low-voltage transformer area loss reduction method for an HPLC application environment belongs to the field of power supply. Carrying out chromatography analysis on the structure of the platform area; analyzing line loss of the power distribution system of the residential floor and the building inner layer line by line and phase by phase according to the wiring mode and the line parameters of the residential floor and the building inner layer; subtracting the technical line loss from the actual measured line loss to obtain the management line loss; implementing technical loss reduction measures on a specific platform area from the angles of interphase load balance and line length rationality; from the angle of correlation accuracy of the subscriber information, the metering problem and the electricity stealing problem, a management loss reduction measure is implemented on a specific distribution area; and excavating loss reduction potential from the three-phase load balance angle of each door opening. Based on the line length and the line-by-line phase line loss analysis results, the construction and operation indexes of the distribution network such as the low-voltage power supply radius, the door opening three-phase load balance degree and the like are further analyzed, the loss reduction means which is only suitable for the medium-voltage and high-voltage distribution networks is popularized and applied to the low-voltage distribution network, and the loss reduction and energy saving of the low-voltage distribution network are promoted. The method can be widely applied to the field of operation management of power supply systems.

Description

Low-voltage transformer area loss reduction method for HPLC application environment

Technical Field

The invention belongs to the field of power supply operation management, and particularly relates to a loss reduction method for line loss of a low-voltage transformer area.

Background

In an electrical power system, a transformer area is generally referred to as a supply range or area of a (single) transformer.

The loss of real power and loss of electrical energy generated during the distribution of the transmission of the power grid are collectively referred to as line losses.

The types of line loss can be generally classified into 5 types, such as statistical line loss, theoretical line loss, management line loss, economic line loss and rated line loss.

The low-voltage transformer area is a main link for generating line loss.

However, under the current line loss refinement platform, the line loss statistical value of the low-voltage distribution area can only be obtained through the comparison of the power supply and sales. Due to meter or communication failure, the statistical value is sometimes not very accurate; even if accurate, also can't distinguish technical line loss and management line loss, can't master the link that the line loss mainly takes place in for low-voltage transformer district line loss administers and lacks effective means.

Most loads of the house are three-level loads, a power supply is generally taken from a 10kV power supply loop of a nearby 110-35/10 kV regional substation, and the power supply is stepped down to 0.4kV power supply through a cell 10kV distribution transformer.

The low-voltage power distribution system of the residential area is divided into two links from the residential area to the building:

(1) cell layer power distribution system: and a link from the outlet of 0.4kV of the community distribution transformer to a unit low-voltage distribution room (for high-rise/small high-rise unit type residence)/unit distribution box (for multi-storey unit type residence). TN-S or TN-C-S three-phase power supply is generally used, and the wiring is radial.

(2) Distribution system in the building: and a link from the unit low-voltage distribution room/unit distribution box to the user electric meter. For a unit type high-rise residence, a small low-voltage distribution room is usually arranged in a unit basement, dual power supplies are distributed in units, and a plurality of low-voltage distribution and metering cabinets are arranged in the distribution room and feed electricity to each floor in a radiation type, a tree-dry type or a partition tree-dry type. For multi-storey houses or villas, a floor type wind and rain box is usually arranged at a proper position in front of the buildings or a floor type wire inlet box is arranged at an entrance of the first storey of the unit to serve as an intermediate power distribution point so as to supply power to each building or each storey in a radial mode. Each cell typically provides three-phase power to facilitate three-phase load balancing. Unit power distribution generally takes two forms: firstly, a unit main switch, a branch switch and each household metering ammeter are arranged in a unit distribution box, and radial wiring is used from the unit distribution box to each household distribution box; secondly, as shown in fig. 1, a unit main switch is arranged in the unit distribution box, trunk wiring is adopted from the unit distribution box to the floor distribution box, a household meter and a distribution switch for the layer are arranged in the floor distribution box, and radial distribution is adopted from the floor distribution box to each household. The latter connection mode is more common at present along with the increase of the scale of the electricity consumption of residents.

At present, a power line high-speed carrier (HPLC) power consumption information acquisition technology is becoming mature. By means of the HPLC and the intelligent electric meter, the power failure time can be reported in time, the voltage, the current and the electric quantity of each 5min of a metering point of a low-voltage user are returned, and the district identification and the phase identification are carried out on the low-voltage user. The functions provide new conditions for mastering the topological structure of the low-voltage distribution network, further accurately analyzing the line loss of the low-voltage transformer area and carrying out the line loss treatment of the low-voltage transformer area.

Based on the above situation, in the aspects of power supply management and energy management, a low-voltage transformer area line loss analysis and treatment method adaptive to a new acquisition environment is urgently needed to be constructed, and the operation efficiency of a low-voltage link is rapidly improved.

Disclosure of Invention

The invention aims to solve the technical problem of providing a low-pressure distribution room loss reduction method aiming at an HPLC application environment. The method comprises the steps of obtaining low-voltage distribution line wiring modes and line parameters in a cell and a building based on voltage, current and electric quantity data obtained by an HPLC (high performance liquid chromatography) at a floor collector and a user; and then calculating the technical line loss of the three-phase line according to the chromatography result, and comparing the technical line loss with the actually measured line loss of the cell to obtain the cell management line loss. By the implementation of the technical scheme, the link of high line loss of the low-voltage transformer area can be found more accurately, so that the line loss is managed more effectively, and the line loss of the low-voltage transformer area is reduced rapidly.

The technical scheme of the invention is as follows: the method for reducing the loss of the low-pressure distribution room aiming at the HPLC application environment is characterized by comprising the following steps of:

1) acquiring a low-voltage distribution network cell layer topology structure diagram from the PMS; acquiring user information from a CIS; acquiring electrical quantity measured by a gateway meter and a user terminal meter side from an HPLC system; acquiring a station area line loss statistic value from a line loss refinement platform;

2) analyzing the structure chromatography of the platform area;

3) analyzing line loss of the power distribution system of the residential floor and the building inner layer line by line and phase by phase according to the obtained wiring mode and line parameters of the residential floor and the building inner layer;

4) subtracting the technical line loss from the actual measured line loss to obtain a management line loss;

5) implementing corresponding technical loss reduction measures for a specific platform area from the angles of interphase load balance and line length rationality;

6) corresponding management loss reduction measure analysis is carried out on a specific transformer area from the angles of correlation accuracy of subscriber information, metering problems and electricity stealing problems;

7) excavating loss reduction potential from the perspective of three-phase load balance of each door opening;

8) based on the analysis results of line length and line loss from line to line and phase to phase, the method further carries out measurement and calculation analysis on distribution network construction and operation indexes such as low-voltage power supply radius, door opening three-phase load balance degree and the like, popularizes and applies loss reduction means which are only suitable for medium-voltage and high-voltage distribution networks to low-voltage distribution networks, and promotes low-voltage distribution network loss reduction and energy conservation.

Specifically, the user information at least comprises a user number, a power utilization address and a table number; the electrical quantities at least comprise voltage, current and electric quantity.

Specifically, the analysis of the distribution room structure chromatography comprises the analysis and graphical display of the distribution system structure diagrams of the cell floor and the inner floor of the building, and the calculation and display of the line parameters of the cell floor and the inner floor of the building;

specifically, the chromatographic analysis of the distribution area structure comprises the analysis and graphical display of the structure diagrams of the power distribution system on the cell layer and the inner floor of the building, and the calculation and display of the line parameters on the cell layer and the inner floor of the building.

In order to test the accuracy of the analysis result of the floor line impedance, for each of n periods for testing, according to the actual load current of each user in the period and the floor line impedance obtained by analysis, the theoretical calculation value of the phase voltage at the position of each layer of collector is calculated, and then the theoretical calculation value is compared with the phase splitting voltage collected at the position of the collector at the same time.

The distribution area structure chromatography at least comprises the analysis of the distribution network in the building and the determination of the phase of each user.

Furthermore, when the phase position of each user is determined, the phase voltage of the s phase at the time of t collected by the f-th layer collector in the door opening is recorded as

The phase voltage measured by the ith user metering device in the layer at the same time is recorded as U_f,i(t), the process of identifying the user phase and identifying the concatenation relationship between users on the same layer is as follows:

the first step is as follows: calculating correlation coefficients of all user phase voltages of the f-th floor and all phase voltages of the floor collector;

the second step is that: for each user belonging to the f-th layer, finding out the phase with the maximum voltage correlation coefficient as the phase to which the user belongs, namely, taking the phase of the ith user of the f-th layer;

the third step: according to the result of the previous step, the users belonging to the s phase of the f layer (s is belonged to { A, B, C }) are subjected to the relation of the users and the same-phase voltage collected by the collector according to the relation

Sequencing from big to small, wherein the relative coefficient is larger and is closest to the collector, thereby determining the series connection relationship between the same-phase users on the same layer;

the fourth step: and repeating the steps 1-3 on all floors f to determine the wiring mode of each phase and obtain the phase position of each user and the series connection relation among the users.

Further, when determining the parameters of each line segment in the zone-level power distribution network, the identification is performed through the following steps:

the first step is as follows: acquiring original data:

the method comprises the following steps: firstly, acquiring the power receiving amount of a layer of collector in a door opening, namely the total power supply amount of the whole door opening; the value is obtained by adding the received electric quantity of all users in the door opening in the time period t and the electric quantity loss value in the time period t in the door opening;

split-phase current of each door opening, namely the sum of currents of all users in the phase of the door opening at the moment t;

③ power supply quantity E of 0.4kV side t period of distribution transformer^T(t); therefore, the total technical loss of the small-area distribution network link in the distribution area in the time period t is obtained, wherein M represents a door opening set in the distribution area;

the second step is that: constructing a downstream node identification matrix gamma according to the community distribution network structure:

the third step: calculating the current on each line segment in the platform area according to the door opening current:

the fourth step: obtaining the resistance value of each line segment by the problem of minimum deviation of loss theoretical value and measured value of each time interval of a cell layer;

the fifth step: for further obtaining branch impedance and further branch reactance and line length, counting the branch nodes in the cell and recording as a set N_C(ii) a For each fork node k e N_CDefining a set of vias L_kEach element in the set corresponding to a way from the node to the end door opening node;

at the same time, for each path L ∈ L_kAll nodes belonging to the path but not including the head node of the path are recorded as a set N_l(ii) a The path L led out according to the bifurcation node belongs to L_kThe calculated voltage of the t-th phase of the bifurcation point k;

and a sixth step: constructing an optimization problem and fitting the impedance Z of each line segment meeting the optimization target_j

The seventh step: from Z_jAnd R_jCalculating reactance X of line segment j_j；

Eighth step: and (5) obtaining the resistance and reactance value of each line segment in unit length and the corresponding line type.

Further, when analyzing the line loss of the distribution system on the district floor and the inner floor of the building line by line and phase by phase, the analysis flow of the technical line loss is as follows:

the first step is as follows: acquiring the split-phase current of each door opening, wherein the value is obtained by adding the current values of all users in the same phase in the time period t in the door opening;

the second step: calculating the current on each line segment in the distribution room according to the current of the door opening;

the third step: the technical line loss of each segment at the time period t of the cell layer of the transformer area can be further written by the current on the line segment;

the fourth step: calculating the three-phase average current and the three-phase current unbalance degree of each door opening;

the fifth step: calculating the neutral line loss of each door opening;

and a sixth step: firstly, calculating the sum of split-phase currents flowing into each door opening so as to obtain the three-phase average current and the three-phase current unbalance degree of a cell layer; further calculating the three-phase average current and the three-phase current unbalance degree of the cell layer;

the seventh step: let the cell layer neutral line resistance be R₀And calculating the neutral line loss of the cell layer.

Further, the technical line loss calculation value is subtracted from the corrected line loss statistical value of the transformer area, and then a transformer area management line loss value can be obtained.

Compared with the prior art, the invention has the advantages that:

1. according to the technical scheme, the analysis of the wiring mode and the line parameters of the low-voltage distribution network is realized by using the measurement data, so that a foundation is provided for the technical loss calculation of a transformer area;

2. based on the structure of the transformer area and the parameter chromatography result, the line-by-line and phase-by-phase technical line loss analysis and the separation of the technical line loss and the management line loss in the low-voltage transformer area can be realized, so that the fine management of the line loss of the low-voltage transformer area is promoted;

3. the method can construct a suspicious user searching method for electricity stealing based on the horizontal migration judgment of the electrical quantity time series by analyzing the time series based on the voltage, the current, the power and the power factor of the user side, improve the timeliness of electricity stealing prevention, and simultaneously estimate the type of electricity stealing;

4. based on the line length and the line-by-line phase line loss analysis result, the construction and operation indexes of the distribution network, such as the low-voltage power supply radius, the door opening three-phase load balance degree and the like, can be further measured, calculated and analyzed, the loss reduction means which is only suitable for the medium-voltage distribution network and the high-voltage distribution network is popularized and applied to the low-voltage distribution network, and the loss reduction and energy saving of the low-voltage distribution network is promoted.

Drawings

FIG. 1 is a schematic diagram of a typical cell floor low voltage power distribution system;

FIG. 2 is a schematic diagram of the identification process of the problem of line loss in the distribution room under the HPLC environment;

fig. 3 is a schematic diagram of the searching process of the suspected electricity stealing user based on the HPLC electrical quantity level migration determination.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

According to the technical scheme, firstly, the low-voltage distribution network structure analysis and the line parameter analysis of a floor line in a door opening and a community power distribution system are carried out by utilizing split-phase voltage, current and power data of a floor collector and a user electric meter in an HPLC system; then, the obtained line parameters are utilized to respectively carry out line-by-line and phase-by-phase line loss calculation on the inner floor of the building and the cell floor, and the separation values of the technical line loss and the management line loss of the cell power distribution system are obtained; then, according to the obtained line length, line-by-line load current and line loss calculation results of all links, appropriate technical loss reduction measures of the target platform area are discussed from the aspects of power supply radius, three-phase balance degree, lead type selection rationality and the like; a method for searching electricity stealing suspicious users based on an electrical quantity time sequence measured by HPLC is provided, and a managerial loss reduction way is explored.

The technical scheme of the invention provides a low-pressure distribution room loss reduction method aiming at an HPLC application environment, which is characterized by comprising the following steps:

1) acquiring a low-voltage distribution network cell layer topology structure diagram from a PMS; acquiring user information from a CIS; acquiring electrical quantity measured by a gateway meter and a user terminal meter side from an HPLC system; acquiring a station area line loss statistic value from a line loss refinement platform;

2) analyzing the structure chromatography of the platform area;

6) corresponding management loss reduction measure analysis is carried out on a specific transformer area from the perspective of correlation accuracy of subscriber information, metering problems and electricity stealing problems;

8) based on the analysis results of line length and line-by-line and phase-by-phase line loss, the construction and operation indexes of the distribution network, such as low-voltage power supply radius, door opening three-phase load balance degree and the like, are further measured, calculated and analyzed, and the loss reduction means which is only suitable for medium and high voltage distribution networks is popularized and applied to the low-voltage distribution network, so that the loss reduction and energy saving of the low-voltage distribution network are promoted.

The technical scheme is further described as follows:

A. analysis of the in-building distribution network:

and (3) collecting phase voltage, phase current and electric quantity at the power receiving point of each user and phase voltage, phase current and electric quantity at the floor collector by using the HPLC, wherein the floor electric quantity is the sum of the power receiving quantity of each phase user at the floor. Most of the residential users adopt single-phase power supply, and the structural analysis of the in-building distribution network comprises the problems of two aspects of identification of the wiring mode of the split-phase low-voltage distribution lines and identification of parameters of various matched lines.

The core problem of the in-building phase-splitting wiring mode identification is to determine the phase of each user.

The phase recognition method provided by the technical scheme is a data analysis method based on user side voltage, current and electric quantity measurement signals, and the result can be used as the supplement of a physical method recognition result; meanwhile, the method is not limited to a physical identification method, because the current physical identification method for transmitting the power line carrier signal only gives the phase of each user and does not determine the front-back sequence relation of wiring among the users, the method provided by the technical scheme can also determine the series connection relation among the users in the same phase while giving a phase identification result.

A1, phase identification:

in each layer, the in-phase users belong to a series connection relationship, and the load change of the downstream users can cause the in-phase change of the voltages of the downstream users and all in-phase upstream and downstream users. Therefore, the voltage fluctuation of the same-layer in-phase user has higher correlation than that of the non-in-phase user, and the closer the two metering points are, the greater the voltage correlation is. According to the principle, the s-phase voltage at the t moment acquired by the f-th layer collector in the door opening is recorded as

the first step is as follows: calculating the correlation coefficient of the phase voltage of all users on the f-th floor and the phase voltage of each floor collector, and recording the correlation coefficient of the phase voltage of the i-th user on the f-th floor and the s-phase voltage collected by the floor collector as gamma_f,s-i。

The second step is that: for each user belonging to the f-th layer, the phase with the maximum voltage correlation coefficient is found as the phase to which the user belongs, namely the phase of the ith user of the f-th layer is taken

s_f,i＝argmax{γ_f,s-i；s∈{A,B,C}}

The third step: according to the last oneStep result, the users belonging to the s phase (s is belonged to { A, B, C }) of the f layer are subjected to relation number according to the same phase voltage collected by the collector

The users are sorted from big to small, the relative coefficient is larger and is closest to the collector, and the concatenation relationship among the same-layer users is determined.

The fourth step: and (4) repeating the steps 1-3 on all floors f, so that the wiring mode of each phase (including the phase of each user and the series connection relationship among the users) can be determined.

The set of users in the f-th layer s phase (s is belonged to { A, B, C }) is recorded as omega_f,s。

A2, identifying floor line parameters:

since the metering devices of the users on the same layer are placed in the same meter box and are very close to each other, the distance and the loss of the part of the line are ignored. Thus, the contents of the floor line parameter identification include: firstly, the length of a line segment between floor collectors; and secondly, impedance of line segments among the floor collectors.

If there is a floor F in the door opening, the floor line length from the F th floor to the F +1 th floor is recorded as

Corresponding resistance is

Reactance is

Keeping the s-phase (s epsilon { A, B, C }) voltage at the f-th layer collector collected in the period t as

The electric quantity transmitted on the s-phase (s epsilon { A, B, C }) floor line from the f th floor to the f +1 th floor of the time interval t is recorded as

The flow of floor line parameter identification is as follows:

the first step is as follows: and acquiring the current value transmitted on the floor line in each time period. The current transmitted on the floor line of a certain section is equal to the sum of the transmitted currents of all the downstream users in the period, i.e. the current transmitted on the floor line of a certain section is equal to the sum of the transmitted currents of all the downstream users in the period of time

In the above formula, the first and second carbon atoms are,

the phase current of t time s obtained by the collector of the k layer is equal to the sum of the current received by all users of the phase of the layer at the time.

The second step is that: and collecting each phase voltage of each time period collected by the floor collector, and solving the voltage loss. Wherein the voltage loss on the f-th to f + 1-th layer s-phase floor lines:

according to the second equation in the above equation, the resistance of the floor line can be theoretically obtained by using the voltage and current values at one time. However, because the voltage and current metering values may have errors, the impedance of the floor line is obtained by adopting a next fitting method.

The third step: for the floor line between two floors, the following minimization problem is constructed, and the impedance of the floor line between each floor in the door opening is fitted by solving the problem

A3, analysis of the cell layer distribution network structure:

the wiring mode of the cell layer power distribution system can be checked in the PMS, so that the structural analysis is mainly used for determining the length, the resistance and the reactance parameter value of each line segment. The basic data identified by the parameters only comprise voltage, current and electric quantity data collected at the outgoing line position of the distribution transformer 0.4kV, the terminal data are the voltage and the current at the position of the first layer collector in the door opening, and in addition, the loss of the floor line in the door opening can be calculated by utilizing the obtained floor line impedance, so that the power supply quantity at the position of the first layer collector in the door opening is reversely pushed out. Based on the data, the technical scheme provides a line loss comparison method to realize the identification of each line segment parameter in the cell layer power distribution network.

The method comprises the following steps:

the first step is as follows: acquiring raw data, comprising: firstly, the received power of a layer of collectors in the door opening, namely the total power supply of the whole door opening is obtained, and the mth door opening is recorded as

The value is obtained by adding the received electric quantity of all users in the door opening at the time period t and the electric quantity loss value of all users in the door opening at the time period t; ② the split-phase current of each door opening, the current at the s-th phase t moment of the kth door opening is recorded as

It is the sum of the currents of all users in the phase of the door opening at the moment t; ③ power supply quantity E of 0.4kV side t period of distribution transformer^T(t) of (d). By

The total technical loss of the small area distribution network link in the station area in the period of t can be obtained (M represents a door opening set in the station area).

The second step is that: and constructing a downstream node identification matrix gamma according to the cell distribution network structure. Wherein, the elements in the downstream node identification matrix take values according to the following rule

The third step: and calculating the current on each line segment in the platform area according to the door opening current. Because the cell distribution network is in a radial wiring mode, each node corresponds to one branch at the upstream of the node, and the current of the branch corresponding to the node can be represented by injecting current into the node. Further, the current at the time t of the s-th phase can be calculated as follows:

in the above formula: n is the number of cell layer nodes in the cell;

the vector is formed by currents at t moment on each line segment of the s phase of the cell layer in the cell;

and a vector formed by injected current at the s-th phase t moment of each node in the transformer area is obtained, and the injected current is equal to the phase current flowing into the door opening only when the node is an end node (namely at the position of the door opening distribution box), otherwise, the injected current is zero.

The theoretical value of the total loss of the cell layer of the station area in the period t can be further written by the current on the line segment as follows:

the fourth step: the resistance value of each line segment is obtained through the problem of minimizing the deviation between the loss theoretical value and the measured value in each time period of the cell layer (as follows):

the fifth step: for further obtaining the branch impedance and further obtaining the branch reactance and the line length, the branch node in the cell (that is, at least two nodes are arranged at the downstream of the node, and the branch node comprises a distribution transformer outlet node, that is, a node with the number of 0) is counted and recorded as a set N_C(ii) a For each fork node k e N_CDefining a set of vias L_kEach element in the set corresponding to a path from the node to the end door opening node; for each channel l∈L_kAll nodes belonging to the path but not including the head node of the path are recorded as a set N_l(ii) a Defining a voltage vector at the s-th phase t moment of a cell end node

The vector dimension is equal to the number of cell nodes, and the corresponding element is non-zero only if the ith node is an end gate node. Thus, the path L ∈ L from the branching node_kThe voltage at the s-th phase t of the bifurcation point k can be calculated according to the following formula:

in the above-mentioned formula, the compound has the following structure,

is a column vector with only the jth element being 1 and the remaining elements being zero; z_jThe impedance of a line segment which takes the jth node as a tail node in the cell.

The above equation indicates that the impedance of each line segment of the cell layer is such that the voltages calculated for each branch node for each path are approximately equal.

The seventh step: from Z_jAnd R_jCalculating reactance X of line segment j_jThe calculation formula is as follows:

the eighth step: and (5) obtaining the resistance and reactance value of each line segment in unit length and the corresponding line type. The method comprises the steps of firstly obtaining a wire impedance angle, and calculating the impedance angle of the jth line segment by the following formula:

comparing the result with the impedance angle of each 0.4kV cable, finding out the nearest line type as the line type, and recording the corresponding resistance and reactance in unit length as r_lAnd x_lThen is obtained by

l_l＝R_l/r_l

Or l_l＝X_l/x_l

The length of this line segment can be determined.

In the past centralized meter reading environment, only a low-voltage transformer area line loss statistical value can be obtained through comparison of the electricity supply and sales, the technical line loss and the management line loss cannot be subdivided, and the occurrence links of the technical line loss cannot be subdivided.

The low-voltage distribution network topology result and the line parameters can be chromatographed in an HPLC (high performance liquid chromatography) collection environment, so that the possibility of calculating the technical line loss according to the load data is provided; the line loss of the platform area management can be further obtained by deducting the technical line loss calculation value from the line loss statistical value; in addition, line-by-line phase-by-phase loss can be determined during technical line loss analysis, and a basis is provided for fine management of line loss of a low-voltage transformer area.

B. The line loss calculation method of the line-by-line and phase-by-phase technology of the transformer area comprises the following steps:

according to the user phase identification and the identification results of the parameters of the segments of the floor line and the community layer power distribution system, the technical line loss of the inner floor and the community layer can be calculated line by line and phase by phase, and the line loss fine analysis is realized. The technical line loss calculation method of the transformer area related by the technical scheme is different from the traditional theoretical line loss calculation method: on one hand, the method in the technical scheme is implemented by line-by-line phase-by-phase calculation; on the other hand, considering that the problem of three-phase load imbalance in a low-voltage distribution system is more prominent, the method constructed in the technical scheme comprises neutral line loss calculation, so that the calculation result can better accord with the actual technical loss of a transformer area.

B1, calculating the line loss of the floor line phase by phase line by line technology:

an F floor is arranged in the door opening, wherein the resistance and reactance of the floor lines from the F floor to the F +1 floor are respectively

(f is 1, …, f-1), the calculation flow of the floor line-by-line loss is as follows:

the first step is as follows: and acquiring the current value transmitted on the floor line in each time period. The current delivered on a floor line is equal to the sum of the currents of all the downstream users in the period of time, i.e. the current is equal to the sum of the currents of all the downstream users in the period of time

In the above formula, the first and second carbon atoms are,

the current at the time t on the s-phase floor line of the f-th to f + 1-th floors; i is_k,i(t) is the current of the ith user of the kth layer at the moment t; omega_f,sIs the set of users for the layer f s phase.

The second step is that: and calculating the line loss of each section of the phase splitting technology according to the calculation result of the resistance and the reactance of each section of the floor line and the current transmitted on the floor line. For the technical line loss on the f-th to f + 1-th floor s-phase floor lines in the time interval t, the calculation formula is

The third step: and calculating the three-phase current unbalance degree of each layer. Firstly, according to the user current value of each layer of the door opening and the identification result of the user phase, calculating the phase separation current value of each layer, further calculating the three-phase current average value of each layer, obtaining the three-phase current unbalance degree of each layer according to the phase separation current value of each layer, and calculating the formula of the phase separation current of the fth layer of the time section t, the three-phase current average value and the three-phase current unbalance degree as follows

Obviously for the unbalance of three-phase current, there are

The fourth step: according to the current value of each layer user and the identification result of the user phase, the neutral line current of each layer is obtained, and the formula for the neutral line current of the f layer of the time period t is as follows

Note the book

Then there is

Expressed by three-phase current unbalance

Is provided with

The fifth step: and calculating the loss of the neutral line of each layer in the door opening. Setting the f-layer neutral resistance as R according to the obtained f-layer neutral current_f,0The neutral line loss of the f-th layer in the time period t is

B2, calculating the line loss of the phase-by-phase line-by-line technology of the cell distribution network:

according to the resistance and reactance values of each line section of the distribution system of the cell layer obtained in the above way, the line-by-line and phase-by-phase calculation can be carried out on the technical line loss of the cell layer by combining the current value of the user ammeter of each door opening.

The technical line loss calculation process is as follows:

the first step is as follows: obtaining the phase-splitting current of each door opening, wherein the value is obtained by adding the current values of the same phase in all the user t periods in the door opening, and the current of the kth door opening at the s-phase t moment is recorded as

The calculation formula is as follows

The second step is that: calculating the current on each line segment in the platform area according to the door opening current, wherein the formula for the current at the s-th phase t moment is

In the above formula, the first and second carbon atoms are,

the vector formed by injected current at the s-th phase t moment of each node in the transformer area is used, and the injected current is equal to the phase current flowing into the door opening only when the node is an end node (namely the door opening), otherwise, the injected current is zero; n is the number of nodes in the cell layer, and each line segment can be divided into its tail nodes according to the tree structure of the cell layerThe points are uniquely represented, and thus

Representing the current on the line segment with node l as the tail node.

The third step: the technical line loss of each segment in the t period of the cell layer of the transformer area can be further written by the current on the line segment, and the calculation formula of the technical loss of the line segment at the s-th phase t moment is

In the above formula, τ is the time interval of current measurement.

The fourth step: the three-phase average current and the three-phase current unbalance degree of each door opening are calculated, and the calculation formula of the three-phase average current and the three-phase current unbalance degree at the kth door opening t moment is

The fifth step: calculating the neutral line loss of each door opening, and setting the neutral line resistance of the kth door opening as R_k,0Then the calculation formula of the neutral line loss at the kth door opening t is

And a sixth step: firstly, the sum of the phase-splitting currents flowing into each door opening is calculated, and therefore the three-phase average current and the three-phase current unbalance degree of the cell layer are obtained. If the community layer has K door openings, the sum of the phase-splitting currents of the door openings is

Further calculating the three-phase average current and the three-phase current unbalance degree of the cell layer

The seventh step: let the cell layer neutral line resistance be R₀Calculating the neutral line loss of the cell layer according to the following formula

B3, calculating the distribution room management line loss:

subtracting the calculated technical line loss value from the corrected line loss statistical value of the distribution room to obtain a distribution room management line loss value, namely

In the above formula,. DELTA.E_MRepresenting the monthly management line loss of the transformer area; e_T(t) is a technical line loss calculated value of a distribution room at the time t, and is calculated according to the following formula

In the above formula, the first and second carbon atoms are,

representing the loss of the distribution line of the cell in the time period t;

and represents the loss of the distribution line in the building in the time period t.

C. The technical loss reduction approach of the low-voltage transformer area is as follows:

under the traditional collection environment, the three-phase unbalance degree can be analyzed in the low-voltage platform area, but how to balance the three-phase load is not known; meanwhile, because the current and the loss on each line cannot be known, other methods capable of analyzing the platform area technology loss reduction measures are also lacked. The HPLC acquisition environment provides possibility for line parameter chromatography and line-by-line phase-by-phase line loss analysis in the transformer area, so that means for analyzing the technical loss reduction way of the low-voltage transformer area are enriched, and the method specifically comprises the following steps:

(1) positioning of three-phase unbalanced door opening: the three-phase unbalance degree of each door opening can be evaluated, and the door opening needing to be subjected to three-phase unbalance treatment is positioned. For the door openings, the three-phase load balance degree can be optimized through user phase adjustment.

(2) Line positioning of load imbalance: load rate balance should be achieved as much as possible among lines led out from the cell distribution transformer, and heavy load of a part of lines and light load of another part of lines are avoided. Therefore, the load rate balance degree evaluation can be carried out on the load rate of the station-to-station outgoing line, and the station area with unbalanced line-to-line load can be found out. For the built transformer area, the line load cutting difficulty is high, but the evaluation result can be used as the evaluation basis of the engineering quality and the reference of the subsequent similar cell wiring engineering.

(3) And (3) judging whether the power supply radius meets the specification: in the provisions of a plurality of technical principles of the power grid, the low-voltage power supply radius is specified to be less than or equal to 150m, but the actual measurement analysis of the low-voltage power supply radius cannot be carried out under the traditional acquisition environment. And according to the chromatography result of the cell distribution network in the chapter II, the lengths of the cell layer and the inner floor line segment are obtained, so that the maximum power supply radius of the cell can be calculated and analyzed, and whether the requirements of the technical principle are met or not is judged. Unreasonable power supply radius is mainly caused by unreasonable addressing and unreasonable wiring of a substation in a community, the power supply radius is not feasible to be shortened for the built community, but the evaluation result can also be used as the evaluation basis of engineering quality and the reference of subsequent similar community wiring engineering.

(4) Analysis of line rationality: and (4) inspecting whether the distribution lines in the district and the distribution lines in the building have perennial heavy-load and light-load lines, and if replacing other line types is helpful to reduce loss, indicating that the unreasonable line type problem exists in the distribution area.

C1, analyzing the unbalance degree of the load among door openings:

the load unbalance among the door openings can be measured by the unbalance of three-phase currents at the door opening, and the calculation formula of the unbalance of the three-phase currents at the kth door opening is as follows

In the formula

And

the largest and smallest phase currents in the k-th door opening at time t, i.e. the phase currents

Wherein

And

at the kth door opening at the time of t

The sum of the currents of the individual users.

The related regulations of the power system stipulate that the unbalance degree of three-phase loads of a main line and main branch lines cannot exceed 20%, the three-phase balance of the main line and each branch line is directly influenced by the three-phase balance of a door opening, so that the judgment standard is popularized to the door opening, and if the unbalance degree of the three-phase current of the door opening is more than 20%, the judgment is unreasonable, namely the three-phase load balance is used as a technical loss reduction measure to be considered for one phase of a corresponding door opening and a corresponding platform area.

If defined, are

Degree of phase current imbalance

Wherein: i is_φFor each phase current, Φ ═ a, B, C }; i is_avIs the three-phase average current. The power loss calculation formula under the condition of considering the three-phase load imbalance is

The cross section of the neutral line in the low-voltage network is the same as that of the phase line, namely R₀So that the above formula can be simplified to

From the above formula, beta in three-phase load balance_A＝β_B＝β_CWhen the line loss Δ P is minimum, 0 is

The line loss is increased when the unbalance degree of the three-phase load is increased, and the line loss is larger when the unbalance degree is larger. Simultaneously, the line loss correction coefficient under the condition of three-phase load unbalance can be obtained

By using the above formula, the reduction value of the line loss of each door opening and the transformer area after the three-phase load unbalance problem is corrected can be evaluated.

C2, analyzing load unbalance degree among lines:

the load of the distribution transformer outgoing line should be balanced as much as possible, and heavy load of some lines and light load of some lines are avoided. However, considering cell door opening placement, inter-line load balancing can only be considered between adjacent wiring. For this purpose, the load unbalance degree between the distribution network lines of the cell is defined as the maximum value of the maximum and minimum power percentage deviation between adjacent lines in the distribution system of the cell within a certain period of time, namely

In the formula: theta is a set of adjacent lines in a cell;

and

respectively the maximum and minimum values of the transmission power at the outlet of the transformer at the instant t of the adjacent line of the σ -th group. The transformer outgoing line transmission power can be obtained by gradually reversing through a method of adding terminal power and line loss under the condition that the power supply amount at the first-layer collector of the door opening is known.

The load balance degree between lines is related to the distribution condition of users in the cell and the electricity utilization habit of the users in each door opening, so the load balance degree between lines can only be used as reference when the reason why the line loss of the low-voltage transformer area is unreasonable is analyzed, and the load balance between lines is difficult to realize through load cutting between lines.

C3, power supply radius rationality analysis:

the supply radius generally refers to the straight-line distance between the substation and the farthest load point it supplies, but the low-voltage supply radius generally refers to the line length, not the spatial distance, between the supply point and the farthest load it supplies.

According to the length of the line segment of the cell layer, the maximum power supply radius of the cell can be calculated and analyzed. For this purpose, the length of the line (hereinafter referred to as a path) from the cell to each door opening is calculated, and the maximum value is the maximum power supply radius of the cell.

According to the line length of each line segment of the cell layer calculated in the previous step, a distribution line long vector L is constructed^XQI.e. by

In the formula I_iRepresents the length of a line segment with the ith node as the tail node, wherein₁0. According to the downstream node identification matrix gamma constructed by the chapter II, the power supply radius vector of each node can be further calculated

As follows

In the node-powered radius vector,

representing the total length of the line from the ith node to the distribution transformer outlet, when i is a door opening node

I.e. the length of one path.

The sum of the floor line lengths in each door opening is then calculated. The maximum length vector of the floor line of the door-recording opening is

In the formula

Representing the maximum length of the floor line of the door opening corresponding to the ith node, if the ith node does not correspond to the door opening, the maximum length of the floor line of the door opening corresponding to the ith node is represented

Otherwise, it is calculated according to the following formula

In the formula

The length of the floor line from the f floor to the f +1 floor of the door opening corresponding to the ith node is shown.

Finally, the maximum radius of the power supply of the cell is determined, i.e.

According to the technical principle, the radius of the low-voltage power supply should not exceed 150m, so that the judgment is made

And if the length exceeds 150m, the length of the line of the cell is unreasonable.

D. A management line loss identification process under an HPLC environment:

the flow of analyzing the problem of managing line loss in the distribution room is shown in fig. 2:

(1) obtaining a management line loss value: and (4) correcting abnormal values in the line loss statistical values of the transformer area, simultaneously performing calculation analysis on the technical line loss of the transformer area, and subtracting the technical line loss of the transformer area in the same period from the line loss statistical values of the transformer area to obtain the management line loss of the transformer area.

(2) Identifying abnormal values of electricity consumption and correcting line loss: and identifying the abnormal data points, and correcting the monthly power consumption of the corresponding users and further the monthly power supply and the line loss of the platform area.

(3) Investigation of electricity stealing behavior in transformer area: and finding out users suspected of stealing electricity in the transformer area, estimating the electricity stealing amount of the users, and further correcting the power supply amount and line loss of the transformer area.

D1, identifying abnormal electricity consumption measurement values and correcting line loss of the distribution room:

the abnormal data acquisition of the power consumption of the user in the HPLC environment mainly has two phenomena: firstly, signal crosstalk caused by carrier communication faults is realized, namely, a table with similar addresses is copied, so that meter skip words appear, and the phenomenon that step mutation occurs in metering data is shown; and the other is the data defects caused by the defects of the meter chip, such as the loss of current and electric quantity. In view of the fact that the first problem only affects the accuracy of the charge amount and the electricity charge of the user, and does not affect the statistics of the electricity sale amount and the line loss of the distribution room, the project only carries out research on the identification of the second problem and the corresponding problem of line loss correction of the distribution room.

After analyzing user-side data collected by HPLC, it is found that data caused by defects of a meter chip are usually represented by current, voltage and no power, wherein the data include two conditions that the power is zero in a part of time period and the power is zero in a whole time period. These zero power situations must be distinguished from a zero charge caused by a power theft by the user.

To this end, note I_k(t)、U_k(t)、P_k(t) current, voltage and power values measured at the kth user metering point at the time t respectively, if the partial time interval satisfies:

I_k(t) > 0 and U_k(t) > 0 and P_k(t)＝0

Then it can be determined that the data is abnormal due to the meter problem; if the current is continuously non-zero and the power is zero, the meter problem or the electricity stealing is possible, and suspected users of electricity stealing need to be listed and determined after manual inspection.

For users satisfying the above conditions, the following formula is adopted to correct the power consumption at the time t

In the above formula, P_k' (t) is the corrected power consumption value of the kth user at the time t;

and taking the power factor value closest to the t moment in the moment when the electric power measurement value of the user is nonzero as the power factor used for the active power correction of the kth user at the moment.

After correcting the power value at the metering point of the user, the monthly electricity sales of the distribution room are calculated according to the following formula

Subsequently, the zone line loss correction value is calculated as follows:

ΔE＝E^G-E^S'

d2, detecting electricity stealing and correcting line loss of transformer area:

the purpose of the electricity stealing detection is to find out the suspected electricity stealing users in the station area.

The solution of this problem in the HPLC collection environment has two major characteristics:

the method comprises the following steps of judging by utilizing measurement values of voltage, current and electric quantity in various aspects, judging suspected users of electricity stealing, and judging the type of electricity stealing according to the combination relationship among a plurality of quantities;

secondly, as a point is collected in 5 minutes, the starting and stopping time of electricity stealing can be accurately judged, and therefore electricity selling quantity and distribution room line loss can be accurately corrected.

(1) The method for searching the electricity stealing suspicious user comprises the following steps:

the combination of the user-side measurement data shown by different electricity stealing means is different: the voltage drop caused by electricity stealing by the voltage loss/undervoltage method further causes the decrease of the active power metering value and the accumulated electricity consumption; the current loss/undercurrent method causes sudden drop of current, and further causes the drop of an active power metering value and accumulated power consumption; the phase-shifting method can cause sudden drop of the power factor, and further cause drop of the active power metering value and the accumulated power consumption, wherein the power factor does not directly display feedback, but can be investigated through the ratio relation of the active power metering value and the product of voltage and current; the voltage, current and power factor change conditions under other electricity stealing modes are complex, the combination condition is not single, but active power and further sudden drop of electricity consumption can be caused.

Any electricity stealing method always causes sudden drop of certain electrical quantity (such as voltage, current, power factor and active power),

d3, a suspicious user search method for electricity stealing based on HPLC electric quantity level migration judgment:

let the time sequence of the electrical acquisition quantity to be examined of user k be x₁，x₂，…，x_nThe collection quantity sequence can be voltage (for under-voltage/under-voltage method), current (for under-current/under-current method), power factor (for phase-shift method), and daily electricity consumption (for other possible electricity stealing modes), and each user can judge whether to classify the user into the suspected electricity stealing user through the process shown in fig. 3.

The method is used for detecting the descending horizontal sudden drop point of the electrical quantity by continuously moving the window, wherein the fixed window sudden drop point detection of each step is implemented by the following steps:

the first step is as follows: the cumulative sum is calculated by the formula

S₀＝0

Wherein

Is x₁x₂…x_nMean value of (i)

The second step is that: the maximum deviation value of the cumulative sum value is calculated by the formula

The third step: calculating accumulated sum values and maximum deviation values of the accumulated sum values according to various permutation and combination of the original time sequence;

rearranging the time sequence x in a random order₁ x₂…x_nThe number of such permutation and combination should be n! -1, 1000 of them were taken for analysis. For the j-th arrangement therein are recorded

Calculating a cumulative sum value

Then calculating the maximum deviation value of the accumulated sum

The fourth step: determine whether there is a certain arrangement j such that

If so, then there may be a horizontal migration with a confidence of the horizontal migration being

In the above formula, N is the experiment times of randomly arranging the original time sequence in other orders, and if all arrangement cases are traversed, N ═ N! -1; in the experiments in which alpha is N

The number of times of (c);

the fifth step: if the confidence coefficient of the horizontal migration is more than or equal to 95 percent, the time when the Level Change occurs is further solved by solving the original stable time sequence

The time m is the time when the mean value changes, and the time m +1 is the first time after the mean value changes;

if x_m<x_m+1, the horizontal migration is upward horizontal migration; if x_m>x_m+1, the horizontal migration is a downward horizontal migration.

Only the user who finds the downward horizontal migration is judged as suspicious of electricity stealing, and the upward horizontal migration time found after the electricity stealing starting time can be used as the electricity stealing stop time.

D4, correction of station power sale and line loss:

by the foregoing electricity theft detection, it has become possible to find out the electricity theft start/stop time of the suspected electricity theft user at the same time. If the suspicious user set of electricity stealing in the found target platform area is Cs, the starting time and the stopping time of the electricity stealing in the current month of the kth user are respectively Cs

And

(both are date numbers, if the electricity stealing is not at the beginning/end of the target month, the two times may be the first day of the month/the last day of the month), the electricity consumption of the user in the same month before the electricity stealing start time is

The electricity sales in the distribution area is corrected by the following formula

In the above formula, n_dTarget total days of the month, E^SAnd E^S' the power is sold in the region before and after correction respectively. Furthermore, when the line loss of the terrace area is corrected according to the following formula:

ΔE＝E^G-E^S'

d5, loss reduction potential analysis:

for the established community, unreasonable power supply radius is difficult to solve through the relocation of a transformer substation, the load unbalance between lines is also limited by load distribution, and the problem of unreasonable line selection does not exist in a test point area. Therefore, the loss reduction potential can only be mined from the door opening three-phase load balancing perspective.

In the process of field test, the three-phase load is cut off for the door opening with the three-phase current unbalance degree exceeding 20%, and if the three-phase load can be completely balanced, the line loss rate of the community is reduced from 4.19% to 3.54%, namely reduced by 0.65% in the test stage.

If the measures of the three-phase load balance of the door opening are expanded and applied to the same type of residential areas of the district of a certain power supply company (the power supply amount is about 100 hundred million kWh/year according to 1.4 ten thousand similar areas), 6500 ten thousand kWh/year can be reduced through the improvement of the three-phase balance degree of the door opening, and the income of the electric charge is increased by 3172 ten thousand yuan/year (the average price per unit is 0.488 yuan/kWh).

The HPLC power consumption information acquisition technology applied to the low-voltage line loss treatment method has the advantages that:

(1) the measurement data can be used for analyzing the wiring mode and the line parameters of the low-voltage distribution network, and further a foundation is provided for the technical loss calculation of the transformer area.

(2) Based on the structure of the transformer area and the parameter chromatography result, the line-by-line and phase-by-phase technical line loss analysis in the low-voltage transformer area and the separation of the technical line loss and the management line loss can be realized, so that the fine management of the line loss of the low-voltage transformer area is promoted.

(3) The method is characterized in that a new method for searching for a suspicious user of electricity stealing based on the horizontal migration judgment of the time series of the electric quantity is constructed by analyzing the time series based on the voltage, the current, the power and the power factor (the ratio of the active power to the U, I product), so that the timeliness of electricity stealing prevention is improved, and the type of electricity stealing can be estimated.

(4) Based on the line length and the line-by-line phase line loss analysis result, the construction and operation indexes of the distribution network, such as the low-voltage power supply radius, the door opening three-phase load balance degree and the like, can be further measured, calculated and analyzed, the loss reduction means which is only suitable for the medium-voltage distribution network and the high-voltage distribution network is popularized and applied to the low-voltage distribution network, and the loss reduction and energy saving of the low-voltage distribution network is promoted.

The invention can be widely applied to the field of operation management of power supply systems.

Claims

1. A low-pressure platform area loss reduction method aiming at an HPLC application environment is characterized in that:

2) analyzing the structure chromatography of the platform area;

analyzing the distribution area structure chromatography, including analyzing and graphically displaying the distribution system structure diagrams of the cell layer and the inner floor of the building, and calculating and displaying the line parameters of the cell layer and the inner floor of the building so as to analyze the distribution network in the building and determine the phase of each user;

when the phase position of each user is determined, the s-phase voltage at the time t acquired by the f-th layer acquirer in the door opening is recorded as

The phase voltage measured by the ith user metering device in the f-th layer at the same time is recorded as U_f,i(t), the process of identifying the user phase and identifying the concatenation relationship between users on the same layer is as follows:

the second step: for each user belonging to the f-th layer, finding out the phase with the maximum voltage correlation coefficient as the phase to which the user belongs, namely, taking the phase of the ith user of the f-th layer;

the third step: according to the result of the last step, the users belonging to the f-th layer s phase are counted according to the relation between the users and the same-phase voltage collected by the collector

Sequencing from big to small, wherein the correlation coefficient is larger and is closest to the collector, thereby determining the series connection relationship between the same-layer and same-phase users, and s belongs to { A, B and C };

the fourth step: repeating the first step to the third step on all floors f, so that the wiring mode of each phase can be determined, and the phase position of each user and the series connection relationship between the users are obtained;

when determining the parameters of each line segment in the zone layer power distribution network, identifying the line segments by the following steps:

the first step is as follows: acquiring original data:

the method comprises the following steps: firstly, acquiring the power receiving amount of a layer of collector in a door opening, namely the total power supply amount of the whole door opening; the value is obtained by adding the receiving electric quantity of all users in the T time period in the door opening and the electric quantity loss value of the T time period in the door opening;

③ power supply quantity E of 0.4kV side T period of distribution transformer^T(t); therefore, the total technical loss of the small-area distribution network link in the distribution area in the T period is obtained, wherein M represents a door opening set in the distribution area;

the fifth step: for further obtaining branch impedance and further branch reactance and line length, counting the branch nodes in the cell and recording as a set N_C(ii) a For each fork node k e N_CDefining a set of vias L_kEach element in the set corresponding to a path from the node to the end door opening node;

Wherein the content of the first and second substances,

is the voltage at time t of the l path; the seventh step: from Z_jAnd R_jCalculating reactance X of line segment j_j(ii) a Wherein R is_jIs the resistance of segment j;

eighth step: obtaining the resistance and reactance value of each line segment in unit length and the corresponding line type;

8) based on the analysis results of line length and line loss from line to line and phase to phase, the low-voltage power supply radius and the door opening three-phase load balance degree distribution network construction and operation indexes are further calculated and analyzed, loss reduction means which are only suitable for medium-voltage and high-voltage distribution networks originally are popularized and applied to the low-voltage distribution network, and loss reduction and energy saving of the low-voltage distribution network are promoted.

2. The method of claim 1, wherein the subscriber information includes at least a subscriber number, a power consumption address, and a table number; the electrical quantities at least comprise voltage, current and electric quantity.

3. The method for reducing the loss of the low voltage transformer area in accordance with claim 1, wherein for the purpose of checking the accuracy of the analysis result of the floor line impedance, for each of n periods for checking, the theoretical calculation value of the phase voltage at the collector of each layer is calculated according to the actual load current of each user and the floor line impedance obtained by analysis at the period, and then compared with the phase-split voltage collected at the collector at the same time.

4. The method for reducing the loss of the low-voltage transformer area in the HPLC application environment as recited in claim 1, wherein when analyzing the line loss of the distribution system on the cell floor and the floor from line to line and from phase to phase, the analysis flow of the technical line loss is as follows:

the first step is as follows: obtaining the phase splitting current of each door opening, wherein the value is obtained by adding the current values of all the users in the same phase in the T time period in the door opening;

the second step is that: calculating the current on each line section in the platform area according to the door opening current;

the third step: the technical line loss of each segment in the T time period of the cell layer of the transformer area can be further written by the current on the line segment;

the fifth step: calculating the neutral line loss of each door opening;

and a sixth step: firstly, calculating the sum of split-phase currents flowing into each door opening, and thus obtaining the three-phase average current and the three-phase current unbalance degree of a cell layer; further calculating the three-phase average current and the three-phase current unbalance degree of the cell layer;

5. The method of claim 1, wherein the line loss of the field management is calculated by subtracting the calculated technical line loss from the corrected statistical line loss of the field.