Theoretical line loss calculation method, system, equipment and medium for end users

Abstract

The theoretical line loss calculation method for end users includes: setting a line meter at the inlet terminal and the outlet terminal of each line in the factory distribution network, and setting a transformer meter at the high-voltage terminal and the low-voltage terminal of each transformer in the factory distribution network; calculating the impedance of each line in the factory distribution network according to the line operation data collected by the line meter, and calculating the no-load loss and load loss of each transformer in the factory distribution network according to the transformer operation data collected by the transformer meter; constructing a theoretical line loss calculation model according to the impedance of each line in the factory distribution network, and the no-load loss and load loss of each transformer in the factory distribution network, and calculating the theoretical line loss of the factory distribution network according to the theoretical line loss calculation model. This design can accurately calculate the theoretical line loss of the factory distribution network when the cable line and transformer parameters in the factory distribution network are not perfect.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method, system, device and medium for calculating theoretical line losses for terminal users, and is specifically applicable to calculating theoretical line losses of a factory distribution network. Background Art

[0002] There are many methods for calculating the theoretical line loss of distribution networks. At present, on the basis of traditional line loss algorithms, a variety of algorithms have been developed in the field of theoretical line loss calculation of distribution networks, including power flow algorithms, fuzzy algorithms, theoretical line loss calculations based on interval mathematics, artificial neural network methods, etc. In recent years, the calculation of line loss has gradually shifted to new processing algorithms represented by artificial neural networks, such as distribution network line loss prediction methods based on support vector regression machines and improved kernel vector machines.

[0003] The main difficulties faced by the existing line loss calculation include the accuracy of line parameters, the variability of loads, and the complexity of the network. Among them, the accuracy of the parameters mainly lies in the fact that the resistance, inductance, capacitance and other parameters of the line have a great influence on the calculation of line loss. The measurement and calculation of these parameters require precise equipment and methods, and will also be affected by environmental factors such as temperature and humidity; the change of load mainly lies in the fact that the size and nature of the load (such as whether it is balanced, power factor, etc.) will affect the size of the line loss, and the load changes with time and user needs, which brings difficulties to the calculation of line loss; the complexity of the network mainly lies in the fact that in the actual power system, the grid structure is complex, and the connection method, length, material of the line, and the operating status of various power supplies, loads and electrical equipment in the grid will also affect the line loss. For the above calculation difficulties, the existing line loss calculation method also has limitations when applied to end-user scenarios. For example, there are few existing studies on line loss calculation scenarios for end-users such as factories, and the factory distribution network often has the problem of difficulty in collecting complete equipment parameters. Especially for line parameters, due to the lack of design documents or frequent changes in the distribution network structure, it is easy to cause the account to be missing. In addition, for plant-level distribution networks with large variations, there are often large differences between design documents and actual parameters, and there is currently no effective solution. Summary of the invention

[0004] The purpose of the present invention is to overcome the line loss calculation scenarios for end users such as factories that exist in the prior art. The factory distribution network often has the problem of difficulty in collecting complete equipment parameters. A method for reversely calculating the line and equipment parameters of each link of the factory distribution network through data collected by the factory metering facilities is provided, and then a theoretical line loss calculation model is established through the complete line and equipment parameters. The theoretical line loss calculation model is used to obtain a theoretical line loss calculation method, system, equipment and medium for end users.

[0005] To achieve the above objectives, the technical solution of the present invention is:

[0006] A theoretical line loss calculation method for end users, the calculation method comprising:

[0007] S1. A line meter is set at the inlet terminal and outlet terminal of each line in the factory distribution network, and a transformer meter is set at the high-voltage terminal and low-voltage terminal of each transformer in the factory distribution network;

[0008] S2. Calculate the impedance of each line in the factory distribution network according to the line operation data collected by the line meter, and calculate the no-load loss and load loss of each transformer in the factory distribution network according to the transformer operation data collected by the transformer meter;

[0009] S3. A theoretical line loss calculation model is constructed according to the impedance of each line in the factory distribution network, and the no-load loss and load loss of each transformer in the factory distribution network. The theoretical line loss of the factory distribution network is calculated according to the theoretical line loss calculation model.

[0010] In the step S1, the factory distribution network includes a high-voltage bus, a factory power bus, and a 0.4KV distribution line. The high-voltage bus is connected to the factory power bus through a factory transformer, and the factory power bus is connected to the 0.4KV distribution line through a distribution transformer.

[0011] The lines in the factory distribution network include: a connection line between a 110KV high-voltage busbar and a high-voltage side of a factory transformer, and a connection line between a 10KV factory power busbar and a high-voltage side of a distribution transformer.

[0012] In the step S1, the line meter measures the line operation data at a frequency of once every M minutes, M≤15; the transformer meter measures the transformer operation data at a frequency of once every N minutes, N≤15;

[0013] In step S2, the line operation data collected by the line meter include: the voltage, active power, and reactive power at the inlet / outlet terminals of the line; the transformer operation data collected by the transformer meter include: the voltage, active power, and reactive power at the high / low voltage side of the transformer.

[0014] In step S2, calculating the impedance of the i-th line in the factory distribution network according to the line operation data collected by the line meter specifically includes:

[0015] S21, calculating the reactance value and standard resistance value of the ith line in the factory distribution network at each moment within a set time period according to the line operation data collected by the line meter;

[0016] S22, constructing a set XT of reactance values ​​of the ith line in the factory distribution network at each moment in a set time period, and a set RT of standard resistance values ​​of the ith line in the factory distribution network at each moment in a set time period, and removing outliers in the set XT and the set RT;

[0017] S23, sorting the reactance values ​​in XT after removing the outliers in order of magnitude to obtain a reactance value sequence sorted in order of magnitude, removing the reactance values ​​in the first 10% and the last 10% of the reactance value sequence, averaging the remaining reactance values ​​in the reactance value sequence, and obtaining the reactance value of the i-th line in the factory distribution network;

[0018] The standard resistance values ​​in the set RT after removing outliers are sorted in order of size to obtain a standard resistance value sequence sorted in order of size, the standard resistance values ​​in the first 10% and the last 10% of the standard resistance value sequence are removed, and the remaining standard resistance values ​​in the standard resistance value sequence are averaged to obtain the standard resistance value of the i-th line in the factory distribution network.

[0019] In step S21, the reactance value X of the ith line in the factory distribution network at time t is calculated according to the line operation data collected by the line meter. t And the standard resistance R t(0) , time t is the time within the set time period, including:

[0020] Get the ambient temperature T at time t;

[0021] The voltage U at the inlet terminal of the i-th line in the factory distribution network at time t is obtained through the line operation data collected by the line meter a , the active power P at the inlet terminal of the i-th line in the factory distribution network at time t a , the active power P at the outlet terminal of the ith line in the factory distribution network at time t b , the reactive power Q at the inlet terminal of the i-th line in the factory distribution network at time t a , the reactive power Q at the outlet terminal of the ith line in the factory distribution network at time t b ;

[0022] Calculate the first resistance R of the i-th line in the factory distribution network at time t according to the power flow relationship in the line t , the reactance value X of the i-th line in the factory distribution network at time t t :

[0023]

[0024]

[0025] Considering the influence of external temperature, according to the first resistance R t Calculate the standard resistance R of the i-th line in the factory distribution network at time t t(0) :

[0026] R t =R t(0) (1+α(T-T0)) (3);

[0027] Where T is the ambient temperature at time t, t0 is the standard temperature, and α is the empirical coefficient.

[0028] In step S22, removing outliers in the set RT specifically includes:

[0029] Calculate the mean μ1 and variance σ1 of each standard resistance value in the set RT 2 :

[0030]

[0031]

[0032] In the formula, R x is the xth standard resistance value in the set RT, and n is the number of standard resistance values ​​in the set RT;

[0033] Calculate the difference between each standard resistance value in the set RT and the mean value μ1. If the difference between any standard resistance value and μ1 is greater than 3σ1 or less than -3σ1, remove the standard resistance value from the set RT.

[0034] In step S202, removing outliers in the set XT specifically includes:

[0035] Calculate the mean μ2 and variance σ2 of each reactance value in the set XT 2 :

[0036]

[0037]

[0038] Where, X x is the xth reactance value in the set XT, and n is the number of reactance values ​​in the set XT;

[0039] Calculate the difference between each reactance value in the set XT and the mean μ2. If the difference between any reactance value and μ2 is greater than 3σ2 or less than -3σ2, remove the reactance value from the set XT.

[0040] In step S2, calculating the no-load loss and load loss of the j-th transformer in the factory distribution network according to the transformer operation data collected by the transformer meter specifically includes:

[0041] Since the j-th transformer in the factory distribution network has the following active power P1 on the high voltage side, active power P2 on the low voltage side, no-load loss P0, and load loss P at any time t: i They all conform to the relationship shown in the following formulas (8) and (9):

[0042] P1-P2=P0+β 2 P i (8);

[0043]

[0044] Where S is the rated capacity of the jth transformer in the factory distribution network;

[0045] Therefore, according to the transformer operation data collected by the transformer meter, the high-voltage side active power and low-voltage side active power of the j-th transformer in the distribution network at each moment in the set time period are obtained, and the high-voltage side active power and low-voltage side active power of the j-th transformer in the distribution network at each moment in the set time period are substituted into formulas (8)-(9), and multiple sets of no-load loss P0 and load loss P0 of the j-th transformer in the factory distribution network are obtained. i The relationship between

[0046] According to the obtained multiple sets of no-load loss P0 and load loss P of the j-th transformer in the factory distribution network i The relationship between P0 and P is obtained by the least square method. i The value of is regressed and the gradient descent method is used to solve P0 and P i The value of .

[0047] A theoretical line loss calculation system for terminal users, the theoretical line loss calculation system is used to execute the above-mentioned theoretical line loss calculation method for terminal users, specifically comprising:

[0048] A data acquisition module is used to acquire the operating data of each line collected by the line meter and the operating data of each transformer in the factory distribution network;

[0049] A parameter calculation module is used to calculate the impedance of each line in the factory distribution network according to the line operation data collected by the line meter, and calculate the no-load loss and load loss of each transformer in the factory distribution network according to the transformer operation data collected by the transformer meter;

[0050] The calculation of the impedance of the i-th line in the factory distribution network according to the line operation data collected by the line meter specifically includes:

[0051] S21, calculating the reactance value and standard resistance value of the ith line in the factory distribution network at each moment within a set time period according to the line operation data collected by the line meter;

[0052] S22, constructing a set XT of reactance values ​​of the ith line in the factory distribution network at each moment in a set time period, and a set RT of standard resistance values ​​of the ith line in the factory distribution network at each moment in a set time period, and removing outliers in the set XT and the set RT;

[0053] S23, sorting the reactance values ​​in XT after removing the outliers in order of magnitude to obtain a reactance value sequence sorted in order of magnitude, removing the reactance values ​​in the first 10% and the last 10% of the reactance value sequence, averaging the remaining reactance values ​​in the reactance value sequence, and obtaining the reactance value of the i-th line in the factory distribution network;

[0054] The standard resistance values ​​in the set RT after removing outliers are sorted in order of size to obtain a standard resistance value sequence sorted in order of size, the standard resistance values ​​in the first 10% and the last 10% of the standard resistance value sequence are removed, and the remaining standard resistance values ​​in the standard resistance value sequence are averaged to obtain the standard resistance value of the i-th line in the factory distribution network.

[0055] In step S21, the reactance value X of the ith line in the factory distribution network at time t is calculated according to the line operation data collected by the line meter. t And the standard resistance R t(0) , time t is the time within the set time period, including:

[0056] Get the ambient temperature T at time t;

[0057] The voltage U at the inlet terminal of the i-th line in the factory distribution network at time t is obtained through the line operation data collected by the line meter a , the active power P at the inlet terminal of the i-th line in the factory distribution network at time t a , the active power P at the outlet terminal of the ith line in the factory distribution network at time t b , the reactive power Q at the inlet terminal of the i-th line in the factory distribution network at time t a , the reactive power Q at the outlet terminal of the ith line in the factory distribution network at time t b ;

[0058] Calculate the first resistance R of the i-th line in the factory distribution network at time t according to the power flow relationship in the line t , the reactance value X of the i-th line in the factory distribution network at time t t :

[0059]

[0060]

[0061] Considering the influence of external temperature, according to the first resistance R t Calculate the standard resistance R of the i-th line in the factory distribution network at time t t(0) :

[0062] R t =R t(0) (1+α(T-T0)) (3);

[0063] Where T is the ambient temperature at time t, t0 is the standard temperature, and α is the empirical coefficient.

[0064] In step S22, removing outliers in the set RT specifically includes:

[0065] Calculate the mean μ1 and variance σ1 of each standard resistance value in the set RT 2 :

[0066]

[0067]

[0068] In the formula, R x is the xth standard resistance value in the set RT, and n is the number of standard resistance values ​​in the set RT;

[0069] Calculate the difference between each standard resistance value in the set RT and the mean value μ1. If the difference between any standard resistance value and μ1 is greater than 3σ1 or less than -3σ1, then remove the standard resistance value from RT.

[0070] In step S202, removing outliers in the set XT specifically includes:

[0071] Calculate the mean μ2 and variance σ2 of each reactance value in the set XT 2 :

[0072]

[0073]

[0074] Where, X x is the xth reactance value in the set XT, and n is the number of reactance values ​​in the set XT;

[0075] Calculate the difference between each reactance value in the set XT and the mean μ2. If the difference between any reactance value and μ2 is greater than 3σ2 or less than -3σ2, remove the reactance value from XT.

[0076] The no-load loss and load loss of each transformer in the factory distribution network are calculated based on the transformer operation data collected by the transformer meter, including:

[0077] Since the j-th transformer in the factory distribution network has the following active power P1 on the high voltage side, active power P2 on the low voltage side, no-load loss P0, and load loss P at any time t: i They all conform to the relationship shown in the following formulas (8) and (9):

[0078] P1-P2=P0+β 2 P i (8);

[0079]

[0080] Where S is the rated capacity of the jth transformer in the factory distribution network;

[0081] Therefore, according to the transformer operation data collected by the transformer meter, the high-voltage side active power and low-voltage side active power of the j-th transformer in the distribution network at each moment in the set time period are obtained, and the high-voltage side active power and low-voltage side active power of the j-th transformer in the distribution network at each moment in the set time period are substituted into formulas (8)-(9), and multiple sets of no-load loss P0 and load loss P0 of the j-th transformer in the factory distribution network are obtained. i The relationship between

[0082] According to the obtained multiple sets of no-load loss P0 and load loss P of the j-th transformer in the factory distribution network i The relationship between P0 and P is obtained by the least square method. i The value of is regressed and the gradient descent method is used to solve P0 and P i The value of .

[0083] The theoretical line loss calculation module is used to build a theoretical line loss calculation model based on the impedance of each line in the factory distribution network, as well as the no-load loss and load loss of each transformer in the factory distribution network, and calculate the theoretical line loss of the factory distribution network based on the theoretical line loss calculation model.

[0084] A theoretical line loss calculation device for end users, comprising a memory and a processor, wherein the memory is used to store computer program codes and transmit the computer program codes to the processor;

[0085] The processor is used to execute the above-mentioned theoretical line loss calculation method for terminal users according to the instructions in the computer program code.

[0086] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned theoretical line loss calculation method for terminal users is implemented.

[0087] Compared with the prior art, the present invention has the following beneficial effects:

[0088] 1. In the theoretical line loss calculation method for terminal users of the present invention, a line meter is set at the inlet terminal and outlet terminal of each line in the factory distribution network, and the line operation data is collected through the line meter. The impedance of each line in the factory distribution network is calculated through the line operation data. For some parameters of the factory distribution network, such as line model, length and other parameters, which are not easy to collect due to the lack of files or frequent changes in the factory distribution network structure, this design can use the collected line operation data to complete the impedance parameters of each line in the factory distribution network, which is convenient for establishing a theoretical line loss calculation model, and then calculating the theoretical line loss of the factory distribution network. Therefore, in this design, a line meter is set at the inlet terminal and outlet terminal of each line in the factory distribution network, and the impedance parameters of each line in the factory distribution network are calculated according to the data collected by the meter, so as to complete the line parameters of the factory distribution network and realize the theoretical line loss calculation when the line parameter ledger is missing or inaccurate.

[0089] 2. In the theoretical line loss calculation method for end users of the present invention, transformer meters are set at the high-voltage side terminals and low-voltage side terminals of each transformer in the factory distribution network, and transformer operation data is collected through the transformer meters. The no-load loss and load loss of each transformer in the factory distribution network are calculated through the transformer operation data. When the nameplate parameters of the transformer in the factory distribution network are incomplete, or the transformer parameters in the factory distribution network are difficult to obtain, the transformer parameters are calculated and supplemented autonomously through the data collected by the transformer meters, which is convenient for establishing a theoretical line loss calculation model, and then the theoretical line loss of the factory distribution network is calculated. Therefore, in this design, transformer meters are set at the high-voltage side terminals and low-voltage side terminals of each transformer in the factory distribution network, and the transformer parameters are calculated and supplemented autonomously through the data collected by the transformer meters, thereby realizing the theoretical line loss calculation when the transformer parameters are incomplete or difficult to obtain.

[0090] 3. In the theoretical line loss calculation method for terminal users of the present invention, multiple groups of data of the same line are continuously collected within a period of time, multiple reactance values ​​and standard resistance values ​​of the same line are calculated, and multiple reactance values ​​and multiple standard resistance values ​​of the same line are respectively constructed into sets, and outlier data in each set are removed, and the data in the set are trimmed and averaged, which can effectively eliminate the influence of abnormal data, and the calculated line impedance is more accurate. Therefore, in this design, the calculation results of multiple parameters of the same line are constructed into a set, and the outlier data in the set are removed and the trimmed average value is calculated, so as to effectively eliminate the influence of abnormal data and make the calculation result more accurate.

[0091] 4. The present invention includes a theoretical line loss calculation system for terminal users, including: a data acquisition module for acquiring the operating data of each line collected by the line meter and the operating data of each transformer in the factory distribution network; a parameter calculation module for calculating the impedance of each line in the factory distribution network according to the line operation data collected by the line meter, and calculating the no-load loss and load loss of each transformer in the factory distribution network according to the transformer operation data collected by the transformer meter; a theoretical line loss calculation module for constructing a theoretical line loss calculation model according to the impedance of each line in the factory distribution network, and the no-load loss and load loss of each transformer in the factory distribution network, and calculating the theoretical line loss of the factory distribution network according to the theoretical line loss calculation model. The system is used to implement the steps of the electric energy metering method based on fast discrete Stockwell transform as provided in any of the above technical solutions. Therefore, the system also includes all the beneficial effects of the theoretical line loss calculation method for terminal users as provided in any of the above technical solutions, which will not be repeated here.

[0092] 5. The present invention includes a theoretical line loss calculation device for terminal users, including a memory and a processor, wherein the memory is used to store computer program codes and transmit the computer program codes to the processor, and the processor is used to execute any of the above-mentioned theoretical line loss calculation methods for terminal users according to the instructions in the computer program codes. Therefore, the device also includes all the beneficial effects of the theoretical line loss calculation method for terminal users provided in any of the above-mentioned technical solutions, which will not be repeated here.

[0093] 6. The present invention includes a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned theoretical line loss calculation method for terminal users is implemented. Therefore, the device also includes all the beneficial effects of the theoretical line loss calculation method for terminal users provided in any of the above-mentioned technical solutions, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] Figure 1 It is a flow chart of the theoretical line loss calculation method for terminal users of the present invention.

[0095] Figure 2 It is a structural schematic diagram of a theoretical line loss calculation system for terminal users of the present invention.

[0096] Figure 3 It is a structural schematic diagram of a theoretical line loss calculation device for terminal users of the present invention.

[0097] Figure 4 It is a structural diagram of the factory distribution network.

[0098] Figure 5It is the equivalent circuit diagram of the distribution line.

[0099] Figure 6 It is the T-type equivalent circuit diagram of the transformer. DETAILED DESCRIPTION

[0100] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0101] Based on the big data of electric power, the present invention proposes a theoretical line loss calculation method for end users. By improving the metering and collection systems of large industrial and high-energy-consuming enterprises, the electrical parameters of each link of the enterprise's distribution network are inferred through the collected data. Finally, a theoretical line loss calculation model is constructed according to the parameter set, and the theoretical line loss calculation result is obtained for the analysis of the enterprise's own line loss, thereby helping the enterprise to reduce the loss of the distribution network.

[0102] Embodiment 1:

[0103] See also Figure 1 ,Theoretical line loss calculation method for terminal users, the calculation method includes:

[0104] S1. Based on the topological structure of the factory distribution network, a line meter is set at the inlet terminal and the outlet terminal of each line in the factory distribution network, and a transformer meter is set at the high-voltage side terminal and the low-voltage side terminal of each transformer in the factory distribution network.

[0105] In step S1, the lines in the factory distribution network refer to distribution lines, including: connection lines between busbars and transformers.

[0106] like Figure 4 As shown, the factory distribution network includes a 110KV high-voltage bus, a 10KV plant power bus, and a 0.4KV distribution line. The 110KV high-voltage bus is connected to each 10KV plant power bus through a plant transformer, and the 10KV plant power bus is connected to each 0.4KV distribution line through a distribution transformer;

[0107] The lines in the factory distribution network include: the connecting line between the 110KV high-voltage bus and the high-voltage side of the factory transformer, the connecting line between the low-voltage side of the factory transformer and the 10KV factory power bus, the connecting line between the 10KV factory power bus and the high-voltage side of the distribution transformer, and the connecting line between the low-voltage side of the distribution transformer and the 0.4KV distribution line.

[0108] For the factory distribution network, the low-voltage side of the plant transformer and distribution transformer is directly connected to the busbar. Generally, meters are installed at the busbar. Therefore, the existing meters at the busbar can be fully utilized to detect the operating data of the outlet side (low-voltage side) of the plant transformer and distribution transformer.

[0109] In step S1, the line meter measures the line operation data at a frequency of once every M minutes, where M≤15; the transformer meter measures the transformer operation data at a frequency of once every N minutes, where N≤15. In this embodiment, the values ​​of M and N are both 15.

[0110] like Figure 4 As shown in the figure, since the voltage level of the 0.4KV distribution line is low and the load it carries is small (such as a small public auxiliary system, etc.), it does not affect the overall situation. In this case, the 0.4KV distribution line and the electrical equipment connected to it do not participate in the line loss calculation. Therefore, each 0.4KV distribution line and its downstream electrical equipment are packaged and regarded as a load as a whole.

[0111] Before calculating the theoretical line loss, it is necessary to ensure that the metering system in the factory distribution network meets the calculation requirements of the theoretical line loss, mainly including: whether the existing meter installation corresponds to the network topology result of the factory distribution network; whether the meter is installed on the outlet side (low voltage side), inlet side (high voltage side), and load of each voltage level transformer; whether the inlet terminal (generally the bus outlet of the substation), the outlet terminal (generally the bus / power cabinet of the power consumption side or the lower substation), and each contact switch of each line are installed with meters; whether each meter meets the collection frequency of every 15 minutes or more intensive collection; for buses and electrical cabinets with related switches such as bus tie switches or standby automatic switching, meters are designed at the switch outlet, and the remote signaling information of the switch should be uploaded at the same time; whether the collected data of the meter covers active power, reactive power, active electricity, reactive electricity and other data with timestamps. In the factory distribution network, since special power consumption equipment such as reactive compensation (SVC, SVG, etc.) can directly collect the metering information of the existing secondary system, there is no need to set up additional meters.

[0112] If the metering system in the factory distribution network does not meet the above requirements, it is necessary to improve the metering system in the factory distribution network in advance.

[0113] Among them, configuring meters on the inlet and outlet sides of the transformer is a general factory management requirement. At present, most factories can install meters on the inlet and outlet sides of the transformer.

[0114] S2. Calculate the impedance of each line in the factory distribution network based on the line operation data collected by the line meter, and calculate the no-load loss and load loss of each transformer in the factory distribution network based on the transformer operation data collected by the transformer meter.

[0115] The line meter and transformer meter are comprehensive measuring instruments that can monitor the voltage, active power and reactive power of the line at the same time. The line operation data collected by the line meter include: the voltage, active power and reactive power at the inlet / outlet terminals of the line; the transformer operation data collected by the transformer meter include: the voltage, active power and reactive power on the high / low voltage side of the transformer.

[0116] After the line meter and transformer meter collect the operation data, active power data, reactive power data, active energy data, and reactive energy data with time stamps are generated according to the collected data.

[0117] In general, when calculating line loss, it is necessary to know the specific line parameters, including line unit impedance (Z0), line length (L), etc. Parameters such as line unit impedance (Z0) and line length (L) can be queried from the user's electrical ledger. For lines with detailed ledgers, the ledger can be queried and the line impedance can be calculated using the formula Z = (R + jX) L, where Z is the impedance value of the line, R and X are the resistance and reactance per unit length of the line queried through the line model, and L is the length of the line. However, in actual situations, the line equipment ledgers at the factory power level often have incomplete data, so the impedance of the line cannot be obtained in the above conventional way. Therefore, it is necessary to calculate the line operation data collected by the road meter to obtain the impedance parameters of each line.

[0118] Similarly, under normal circumstances, transformer parameters can be completely obtained through nameplate parameters. Since some transformer nameplates include all data such as voltage level (UN), capacity (S), no-load loss (P0), load loss (Pi), short-circuit impedance (Uk%), and no-load current (I0), while some transformer nameplates only contain key data such as capacity, model, and voltage level, when such data cannot be obtained, the no-load loss and load loss of each transformer in the factory distribution network can only be calculated based on the transformer operation data collected by the transformer meter.

[0119] At present, the calculation methods of theoretical line loss include the loss rate method based on the measured line loss, the equivalent resistance method, the modified equivalent resistance method, the forward-backward method, the power flow method, etc., and this embodiment improves the metering system under the premise that the basic data is limited or missing, maximizes the use of the existing metering system, adds the calculation steps of the cable line and transformer parameters, improves the basic data of the factory distribution network, makes the basic data of the factory distribution network meet the needs of calculating the line loss by the power flow method, and accurately calculates the theoretical line loss according to the power flow method, which is conducive to realizing the lean management of the factory distribution network.

[0120] In step S2, calculating the impedance of the i-th line in the factory distribution network according to the line operation data collected by the line meter specifically includes:

[0121] S21, calculating the reactance value and standard resistance value of the ith line in the factory distribution network at each moment within a set time period according to the line operation data collected by the line meter;

[0122] S22, constructing a set XT of reactance values ​​of the ith line in the factory distribution network at each moment in a set time period, and a set RT of standard resistance values ​​of the ith line in the factory distribution network at each moment in a set time period, and removing outliers in the set XT and the set RT;

[0123] S23. Calculate the reactance value of the ith line in the factory distribution network and the standard resistance value of the ith line in the factory distribution network by using the trimmed mean value: sort the reactance values ​​in XT after removing the outliers in order of magnitude to obtain a reactance value sequence sorted in order of magnitude, remove the reactance values ​​in the first 10% and the last 10% of the reactance value sequence, and average the remaining reactance values ​​in the reactance value sequence to obtain the reactance value of the ith line in the factory distribution network;

[0124] The standard resistance values ​​in the set RT after removing outliers are sorted in order of size to obtain a standard resistance value sequence sorted in order of size, the standard resistance values ​​in the first 10% and the last 10% of the standard resistance value sequence are removed, and the remaining standard resistance values ​​in the standard resistance value sequence are averaged to obtain the standard resistance value of the i-th line in the factory distribution network.

[0125] In step S21, the reactance value X of the ith line in the factory distribution network at time t is calculated based on the line operation data collected by the line meter. t And the standard resistance R t(0) , time t is the time within the set time period, including:

[0126] Get the ambient temperature T at time t;

[0127] The voltage U at the inlet terminal of the i-th line in the factory distribution network at time t is obtained through the line operation data collected by the line meter a , the active power P at the inlet terminal of the i-th line in the factory distribution network at time t a , the active power P at the outlet terminal of the ith line in the factory distribution network at time t b , the reactive power Q at the inlet terminal of the i-th line in the factory distribution network at time t a , the reactive power Q at the outlet terminal of the ith line in the factory distribution network at time t b ;

[0128] First, the equivalent circuit of the distribution line is as follows Figure 5As shown in the figure, the mathematical model of the line is established based on the equivalent circuit of the distribution line.

[0129] According to the power flow relationship in the line:

[0130]

[0131] Therefore, according to the power flow relationship in the line, the first resistance R of the i-th line in the factory distribution network at time t can be calculated: t , the reactance value X of the i-th line in the factory distribution network at time t t :

[0132]

[0133]

[0134] At the same time, since temperature has an effect on resistance but no significant effect on reactance, considering the influence of external temperature, according to the first resistance R t Calculate the standard resistance R of the i-th line in the factory distribution network at time t t(0) :

[0135] R t =R t(0) (1+α(T-T0)) (3);

[0136] Wherein, T is the ambient temperature at time t, t0 is the standard temperature, in this embodiment, t0=20°C, α is the empirical coefficient, for copper wire, α is 0.0039 / °C; for aluminum wire, α is 0.00403 / °C.

[0137] Since in this embodiment, the line meter measures the line operation data at a frequency of once every 15 minutes, and the transformer meter measures the transformer operation data at a frequency of once every 15 minutes, in this embodiment, the set time period is taken as the past week, that is, the sampled data in the past week is used for calculation, so a total of 627 groups of data are collected in the past week, and therefore, according to the collected data, a total of 627 reactance values ​​and 627 standard resistance values ​​can be obtained for each line. Based on the above calculation process, in this embodiment, the set RT includes 627 standard resistance values, and similarly, the set XT includes 627 reactance values.

[0138] In step S22, removing outliers in the set RT specifically includes:

[0139] Calculate the mean μ1 and variance σ1 of each standard resistance value in the set RT 2 :

[0140]

[0141]

[0142] In the formula, R x is the xth standard resistance value in the set RT, n is the number of standard resistance values ​​in the set RT, σ1≥0;

[0143] Calculate the difference between each standard resistance value in the set RT and the mean μ1. If the difference between any standard resistance value and μ1 is greater than 3σ1 or less than -3σ1, remove the standard resistance value from the set RT.

[0144] Under the assumption of normal distribution, μ1±3σ1 2 The region contains 99.7% of the data. If a value is more than 3σ1 away from μ1, then this value can be simply marked as an outlier and the data can be directly deleted.

[0145] In step S202, removing outliers in the set XT specifically includes:

[0146] Calculate the mean μ2 and variance σ2 of each reactance value in the set XT 2 :

[0147]

[0148]

[0149] In the formula, X x is the x-th reactance value in the set XT, n is the number of reactance values ​​in the set XT, σ2 ≥ 0;

[0150] Calculate the difference between each reactance value in the set XT and the mean μ2. If the difference between any reactance value and μ2 is greater than 3σ2 or less than -3σ2, the reactance value can be judged as an abnormal value and is removed from the set XT.

[0151] By removing outliers in the set RT and using the trimmed mean to calculate the reactance value of the ith line in the factory distribution network and the standard resistance value of the ith line in the factory distribution network, the influence of meter data jumps, data distortion caused by extreme temperatures, etc. on the data samples can be effectively eliminated, making the calculation results more accurate.

[0152] In this embodiment, the set time period is the past week, that is, the calculation is performed based on the sampling data in the past week. Since the meters in the factory distribution network continuously acquire new data, after the meters collect new real-time data, the reactance value of each line in the factory distribution network and the standard resistance value of each line in the factory distribution network are calculated and updated according to the real-time data.

[0153] In step S2, calculating the no-load loss and load loss of the j-th transformer in the factory distribution network according to the transformer operation data collected by the transformer meter specifically includes:

[0154] First, the transformer is simulated using the T-type equivalent circuit of the transformer. Figure 6 As shown by Figure 6 It can be seen that:

[0155] δP=P1-P2=P0+P i '=P0+β 2 P i (12);

[0156] Therefore, at any time t, the high-voltage side active power P1, low-voltage side active power P2, no-load loss P0, and load loss P i They all conform to the relationship shown in the following formulas (8) and (9):

[0157] P1-P2=P0+β 2 P i (8);

[0158]

[0159] Where S is the rated capacity of the jth transformer in the factory distribution network;

[0160] Therefore, according to the transformer operation data collected by the transformer meter, the high-voltage side active power and low-voltage side active power of the j-th transformer in the distribution network at each moment in the set time period are obtained, and the high-voltage side active power and low-voltage side active power of the j-th transformer in the distribution network at each moment in the set time period are substituted into formulas (8)-(9), and multiple sets of no-load loss P0 and load loss P0 of the j-th transformer in the factory distribution network are obtained. i Since in this embodiment, the past week is taken in the set time period, that is, the sampling data in the past week is used for calculation, and the line meter measures the line operation data once every 15 minutes, and the transformer meter measures the transformer operation data once every 15 minutes, a total of 627 sets of data are collected in the past week, and a total of 627 sets of no-load loss P0, load loss P0 of the j-th transformer in the factory distribution network are obtained. i The relationship formula.

[0161] Set the error function for the regression calculation:

[0162]

[0163] According to the obtained multiple sets of no-load loss P0 and load loss P of the j-th transformer in the factory distribution network i The relationship between P0 and P is obtained by the least square method. i The value of is regressed and the gradient descent method is used to solve P0 and P i The value of .

[0164] S3. A theoretical line loss calculation model is constructed according to the impedance of each line in the factory distribution network, and the no-load loss and load loss of each transformer in the factory distribution network. The theoretical line loss of the factory distribution network is calculated according to the theoretical line loss calculation model.

[0165] The theoretical line loss of the factory distribution network calculated according to the theoretical line loss calculation model includes: the active loss of each transformer and the active loss data of each branch line, among which the active loss of the transformer includes iron loss and copper loss.

[0166] Since all the parameters required for calculating the theoretical line loss of the factory distribution network have been obtained in step S2, and considering the three-phase imbalance problem of large industrial users, the AC three-phase balanced power flow model is used in this embodiment to construct a theoretical line loss calculation model to obtain a more accurate theoretical line loss calculation result. At the same time, since the power flow calculation method is relatively mature, various conventional methods such as Newton iteration method and Gauss method can be used to carry out the calculation, which will not be elaborated here.

[0167] The lack of complete and accurate data in the records and design documents of cable lines is a practical problem often encountered by large industrial users. This method constructs a reasonable and standard measurement system from the perspective of end users. Through the data of each meter in the measurement system, the parameters of the components (cable lines, transformers) are calculated without complete component parameters. Then the theoretical line loss is accurately calculated and the theoretical line loss analysis is carried out. Based on the theoretical line loss calculation results, the copper loss, iron loss, and line loss calculation values ​​of each voltage level are generated to form a theoretical line loss report for voltage division and component division, which is compared with the actual line loss of the collected data, which can be used to explore the hidden loss reduction space. For lines with existing impedance parameters, the theoretical impedance can be calculated based on the line unit impedance (Z0) and line length (L), and then the theoretical impedance can be compared with the actual impedance, which can be used to verify whether the line record is correct.

[0168] At the same time, while this method solves the problem of theoretical line loss calculation, the calculated parameters can also help enterprises archive and analyze basic data, which has value beyond line loss management.

[0169] Embodiment 2:

[0170] See also Figure 2, a theoretical line loss calculation system for terminal users, the theoretical line loss calculation system is used to execute the theoretical line loss calculation method for terminal users as described in Example 1, specifically comprising:

[0171] A data acquisition module, used to acquire the operating data of each line collected by the line meter and the operating data of each transformer of the factory distribution network. The data acquisition module is used to acquire the data collected by the line meter and the transformer meter in Example 1;

[0172] A parameter calculation module, used to calculate the impedance of each line in the factory distribution network according to the line operation data collected by the line meter, and calculate the no-load loss and load loss of each transformer in the factory distribution network according to the transformer operation data collected by the transformer meter. The parameter calculation module is used to execute step S2 in Example 1;

[0173] The theoretical line loss calculation module is used to construct a theoretical line loss calculation model according to the impedance of each line in the factory distribution network, and the no-load loss and load loss of each transformer in the factory distribution network, and calculate the theoretical line loss of the factory distribution network according to the theoretical line loss calculation model. The theoretical line loss calculation module is used to execute step S3 in Example 1.

[0174] Embodiment 3:

[0175] See also Figure 3 , a theoretical line loss calculation device for end users, comprising a memory and a processor, wherein the memory is used to store computer program codes and transmit the computer program codes to the processor;

[0176] The processor is used to execute the theoretical line loss calculation method for terminal users as described in Example 1 according to the instructions in the computer program code.

[0177] Embodiment 4:

[0178] A computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the theoretical line loss calculation method for terminal users as described in Example 1.

[0179] Generally speaking, the computer instructions for implementing the method of the present invention may be carried in any combination of one or more computer-readable storage media. Non-transitory computer-readable storage media may include any computer-readable media, except for the signal itself that is temporarily propagating.

[0180] Computer-readable storage media, for example, may be, but are not limited to, electrical, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or devices, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection with one or more conductors, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with a system, device or device for executing instructions.

[0181] One or more programming languages ​​or their combinations can be used to write computer program codes for performing the operation of the present invention. These programming languages ​​include object-oriented programming languages, such as Java, Smalltalk, C++, and also include conventional procedural programming languages, such as C language or similar programming languages. In particular, Python language suitable for neural network calculations and platform frameworks based on TensorFlow, PyTorch, etc. can be used. The program code can be executed completely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer and partially on the remote computer, or completely on the remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through various types of networks, including a local area network (LAN) or a wide area network (WAN), or an Internet connection is performed through an Internet service provider.

[0182] Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. The theoretical line loss calculation method for end users is characterized by: The calculation method includes: S1. A line meter is set at the inlet terminal and outlet terminal of each line in the factory distribution network, and a transformer meter is set at the high-voltage terminal and low-voltage terminal of each transformer in the factory distribution network; S2. Calculate the impedance of each line in the factory distribution network according to the line operation data collected by the line meter, and calculate the no-load loss and load loss of each transformer in the factory distribution network according to the transformer operation data collected by the transformer meter; S3. Use the AC three-phase balanced power flow model to construct a theoretical line loss calculation model. According to the impedance of each line in the factory distribution network, and the no-load loss and load loss of each transformer in the factory distribution network, a theoretical line loss calculation model is constructed. The theoretical line loss of the factory distribution network is calculated according to the theoretical line loss calculation model. In step S2, calculating the impedance of the i-th line in the factory distribution network according to the line operation data collected by the line meter specifically includes: S21, calculating the reactance value and standard resistance value of the ith line in the factory distribution network at each moment within a set time period according to the line operation data collected by the line meter; S22, constructing a set XT of reactance values ​​of the ith line in the factory distribution network at each moment in a set time period, and a set RT of standard resistance values ​​of the ith line in the factory distribution network at each moment in a set time period, and removing outliers in the set XT and the set RT; S23, sorting the reactance values ​​in the set XT after removing the outliers in order of magnitude to obtain a reactance value sequence sorted in order of magnitude, removing the reactance values ​​in the first 10% and the last 10% of the reactance value sequence, averaging the remaining reactance values ​​in the reactance value sequence, and obtaining the reactance value of the i-th line in the factory distribution network; The standard resistance values ​​in the set RT after removing the outliers are sorted in order of magnitude to obtain a standard resistance value sequence sorted in order of magnitude, the standard resistance values ​​in the first 10% and the last 10% of the standard resistance value sequence are removed, and the remaining standard resistance values ​​in the standard resistance value sequence are averaged to obtain the standard resistance value of the i-th line in the factory distribution network; In step S21, the reactance value X of the ith line in the factory distribution network at time t is calculated according to the line operation data collected by the line meter. t And the standard resistance R t(0)， Specifically include: Get the ambient temperature T at time t; The voltage U at the inlet terminal of the i-th line in the factory distribution network at time t is obtained through the line operation data collected by the line meter a , the active power P at the inlet terminal of the i-th line in the factory distribution network at time t a , the active power P at the outlet terminal of the i-th line in the factory distribution network at time t b , the reactive power Q at the inlet terminal of the i-th line in the factory distribution network at time t a , the reactive power Q at the outlet terminal of the ith line in the factory distribution network at time t b ; Calculate the first resistance R of the i-th line in the factory distribution network at time t according to the power flow relationship in the line t , the reactance value X of the i-th line in the factory distribution network at time t t : Considering the influence of external temperature, according to the first resistance R t Calculate the standard resistance R of the i-th line in the factory distribution network at time t t(0) : R t =R t(0) (1+α(T-T0)) (3); In the formula, T is the ambient temperature at time t, t0 is the standard temperature, and α is the empirical coefficient; In step S22, removing outliers in the set RT specifically includes: Calculate the mean μ1 and variance σ1 of each standard resistance value in the set RT 2 : In the formula, R x is the xth standard resistance value in the set RT, and n is the number of standard resistance values ​​in the set RT; Calculate the difference between each standard resistance value in the set RT and the mean value μ1. If the difference between any standard resistance value and μ1 is greater than 3σ1 or less than -3σ1, remove the standard resistance value from the set RT. In step S22, removing outliers in the set XT specifically includes: Calculate the mean μ2 and variance σ2 of each reactance value in the set XT 2 : Where, X x is the xth reactance value in the set XT, and n is the number of reactance values ​​in the set XT; Calculate the difference between each reactance value in the set XT and the mean μ2. If the difference between any reactance value and μ2 is greater than 3σ2 or less than -3σ2, remove the reactance value from the set XT. In step S2, calculating the no-load loss and load loss of the j-th transformer in the factory distribution network according to the transformer operation data collected by the transformer meter specifically includes: Since the active power P1 on the high-voltage side of the j-th transformer in the factory distribution network is 、 Low voltage side active power P2 、 No-load loss P0, load loss P i They all conform to the relationship shown in the following formulas (8) and (9): P1-P2=P0+β 2 P i (8); Where S is the rated capacity of the jth transformer in the factory distribution network; Therefore, according to the transformer operation data collected by the transformer meter, the high-voltage side active power and low-voltage side active power of the j-th transformer in the distribution network at each moment in the set time period are obtained, and the high-voltage side active power and low-voltage side active power of the j-th transformer in the distribution network at each moment in the set time period are substituted into formulas (8)-(9), and multiple sets of no-load loss P0 and load loss P0 of the j-th transformer in the factory distribution network are obtained. i The relationship between According to the obtained multiple sets of no-load loss P0 and load loss P of the j-th transformer in the factory distribution network i The relationship between P0 and P is obtained by the least square method. i The value of is regressed and the gradient descent method is used to solve P0 and P i The value of .

2. The method for calculating theoretical line loss for terminal users according to claim 1, characterized in that: In the step S1, the factory distribution network includes a high-voltage bus, a factory power bus, and a 0.4KV distribution line. The high-voltage bus is connected to the factory power bus through a factory transformer, and the factory power bus is connected to the 0.4KV distribution line through a distribution transformer. The lines in the factory distribution network include: a connection line between a 110KV high-voltage busbar and a high-voltage side of a factory transformer, and a connection line between a 10KV factory power busbar and a high-voltage side of a distribution transformer.

3. The method for calculating theoretical line loss for terminal users according to claim 1, characterized in that: In the step S1, the line meter measures the line operation data at a frequency of once every M minutes, M≤15; the transformer meter measures the transformer operation data at a frequency of once every N minutes, N≤15; In step S2, the line operation data collected by the line meter include: the voltage, active power, and reactive power at the inlet / outlet terminals of the line; the transformer operation data collected by the transformer meter include: the voltage, active power, and reactive power at the high / low voltage side of the transformer.

4. A theoretical line loss calculation system for terminal users, characterized in that: The theoretical line loss calculation system is used to execute the theoretical line loss calculation method for terminal users according to any one of claims 1 to 3, specifically comprising: A data acquisition module is used to acquire the operating data of each line collected by the line meter and the operating data of each transformer in the factory distribution network; A parameter calculation module is used to calculate the impedance of each line in the factory distribution network according to the line operation data collected by the line meter, and calculate the no-load loss and load loss of each transformer in the factory distribution network according to the transformer operation data collected by the transformer meter; The theoretical line loss calculation module is used to construct a theoretical line loss calculation model according to the impedance of each line in the factory distribution network, and the no-load loss and load loss of each transformer in the factory distribution network, and calculate the theoretical line loss of the factory distribution network according to the theoretical line loss calculation model.

5. A theoretical line loss calculation device for terminal users, characterized in that: The method comprises a memory and a processor, wherein the memory is used to store computer program code and transmit the computer program code to the processor; The processor is used to execute the theoretical line loss calculation method for terminal users as described in any one of claims 1 to 3 according to the instructions in the computer program code.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for calculating theoretical line loss for terminal users described in any one of claims 1 to 3 is implemented.

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