Calculation method of line loss rate of low-voltage distribution network containing photovoltaic power source based on voltage loss

Abstract

The present invention discloses a method for calculating the line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss. The method first calculates the voltage change at the distribution network node after the photovoltaic power source is connected. Then, a method combining the Pearson correlation coefficient and the cosine distance is used to comprehensively consider two types of data, voltage drop and photovoltaic output time, to analyze the specific absorption range of each photovoltaic area. Finally, a specific calculation process for the line loss of the low-voltage distribution network is given after the absorption range of the photovoltaic area is delineated. This method clarifies the variation pattern of line node voltage after the photovoltaic power source is connected to the distribution network, improves the accuracy of the division of the absorption range of the photovoltaic area, and provides data support for the study of theoretical line loss in photovoltaic areas. The method proves the consistency between the line loss rate calculated by the proposed method and the actual theoretical line loss rate, thereby improving the calculation accuracy of the line loss rate in photovoltaic areas.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution networks, and more particularly to a method for calculating line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss. Background Art

[0002] The presence of resistance in lines, transformers, and series reactors in distribution networks results in power and energy losses when current flows through them. Accurately calculating theoretical line losses helps reduce losses and save energy, enhances precision in line loss management, and helps businesses ensure economic benefits. The voltage loss method is widely used to calculate line loss rates in low-voltage distribution networks due to its advantages, including minimal data requirements, simple procedures, and high accuracy.

[0003] The voltage drop method calculates theoretical line loss based on the proportional relationship between the percentage of voltage loss and the percentage of power loss in a substation. The voltage loss rate method uses the easily measurable percentage of voltage loss to calculate line loss in a substation. The voltage drop method uses the voltage difference between each user in the substation at any given moment. For non-PV substations (single power supply), this method uses the total meter active power curve, reactive power curve, user phase sequence, voltage curve, current curve, and power factor curve for accurate calculations.

[0004] As the number of clean distributed photovoltaic power sources connected to the distribution network increases, the distribution of power flow in the distribution network is affected, resulting in changes in line node voltage. The traditional voltage loss method for calculating line loss has large errors and cannot accurately reflect changes in line loss. For photovoltaic substations, the calculated theoretical value has a large deviation because it involves the issue of multiple power sources (municipal power supply and photovoltaic power generation users). The voltage drop calculation method requires determining many variables (the power supply source of the electricity user at each moment is required to determine the head-end voltage). It is necessary to calculate the power supply source of the electricity user at each moment based on the data, that is, to identify the users who consume the photovoltaic grid meter, improve the accuracy of the theoretical line loss calculation of the voltage drop method, and thus adapt to the lean management of photovoltaic substation line losses. Summary of the Invention

[0005] In response to the problem of low calculation accuracy of the theoretical line loss rate of photovoltaic areas in the existing technology, the present invention provides a method for calculating the line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss, which improves the accuracy of the division of the absorption range of photovoltaic areas in the active distribution network, and thus realizes the accurate calculation of the theoretical line loss rate of photovoltaic areas.

[0006] One aspect of the present invention provides a method for calculating line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss, comprising:

[0007] The matrix transformation of the low-voltage distribution network power flow equation after accessing the photovoltaic power source is carried out, the sensitivity factor is introduced, and the sensitivity factor and the injected active power ΔP are used to calculate the power flow equation. jand reactive power ΔQ j The relationship between the two factors is used to calculate the change in the voltage at the distribution network node after the photovoltaic power source is connected, wherein the sensitivity factor represents the influence of the active / reactive output of the photovoltaic power source on the node voltage amplitude / phase angle;

[0008] The specific absorption range of each photovoltaic area is analyzed based on two types of data: voltage drop and photovoltaic output time, using a method combining the Pearson correlation coefficient and cosine distance.

[0009] Based on the basic archival data of the marketing system, the voltage curve of the total meter of the procurement system, the voltage, current, power factor curve of low-voltage users and the daily load power data, the active substation is divided into multiple passive substations according to the specific absorption range. The theoretical loss power of each passive substation after the split is calculated separately by measuring the pressure difference loss between the substation head end and each user according to the proportional relationship between the substation voltage loss percentage and the power loss percentage, and the theoretical line loss of the active substation is obtained by cumulative calculation.

[0010] Alternatively, a method combining the Pearson correlation coefficient and cosine distance can be used to analyze the specific absorption range of each PV area based on two types of data: voltage drop and PV output time. This includes:

[0011] Acquire data, wherein the data includes a statistical table of line losses in the substation area, details of daily power consumption of users, voltage curve data, current curve data, power factor curve data, power curve data, the relationship between the transformer and the meter box, and the relationship between the meter box and the meter;

[0012] Based on the acquired data, the neighboring users of the photovoltaic user are determined using the voltage drop method or the correlation method of the photovoltaic output time;

[0013] Based on the time-sharing and phase-sharing voltage, current, power and neighboring users, users with abnormal current and voltage are eliminated, and the absorption range is designed as an optimization problem under multiple constraints. The absorption users are determined through genetic algorithms, and finally the specific absorption range of each photovoltaic area is determined.

[0014] Optionally, the voltage drop method is used to determine the neighboring users of the photovoltaic user, including:

[0015] Determine the relative position of each user in the substation and the assessment table from the voltage perspective, and thus determine the neighboring users of the photovoltaic user.

[0016] Optionally, a correlation method of photovoltaic output time is used to determine neighboring users of a photovoltaic user, including:

[0017] Determine the photovoltaic output time based on the changing pattern of the current curve of the grid meter at the time of photovoltaic output and the time of no output;

[0018] The multi-day voltage curves of the substation power meters and ordinary user meters at the time of photovoltaic output were analyzed. The Pearson correlation coefficient method was combined with the cosine distance method to calculate the correlation and distance between the voltage curves of the users under the substation and the voltage curves of the substation power meters. The results of the two methods of correlation and distance calculation were comprehensively weighted and sorted to determine the adjacent users of the photovoltaic users.

[0019] Another aspect of the present invention provides a device for calculating line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss, comprising:

[0020] The voltage change calculation module is used to perform matrix transformation on the low-voltage distribution network power flow equation after the photovoltaic power source is connected, introduce the sensitivity factor, and use the sensitivity factor and the injected active power ΔP j and reactive power ΔQ j The relationship between the two factors is used to calculate the change in the voltage at the distribution network node after the photovoltaic power source is connected, wherein the sensitivity factor represents the influence of the active / reactive output of the photovoltaic power source on the node voltage amplitude / phase angle;

[0021] The absorption range determination module is used to analyze the specific absorption range of each photovoltaic area based on two types of data: voltage drop and photovoltaic output time, using a method combining the Pearson correlation coefficient and cosine distance;

[0022] The loss rate calculation module is used to split the active substation into multiple passive substations according to the specific absorption range based on the basic archival data of the marketing system, the voltage curve of the total meter of the procurement system, the voltage, current, power factor curve of the low-voltage users and the daily load power data. After the split, the theoretical loss power of each passive substation is calculated separately according to the proportional relationship between the voltage loss percentage and the power loss percentage of the substation by measuring the pressure difference loss between the substation head end and each user, and the theoretical line loss of the active substation is obtained by cumulative calculation.

[0023] Optionally, the absorption range determination module is specifically configured to:

[0024] Acquire data, wherein the data includes a statistical table of line losses in the substation area, details of daily power consumption of users, voltage curve data, current curve data, power factor curve data, power curve data, the relationship between the transformer and the meter box, and the relationship between the meter box and the meter;

[0025] Based on the acquired data, the neighboring users of the photovoltaic user are determined using the voltage drop method or the correlation method of the photovoltaic output time;

[0026] Based on the time-sharing and phase-sharing voltage, current, power and neighboring users, users with abnormal current and voltage are eliminated, and the absorption range is designed as an optimization problem under multiple constraints. The absorption users are determined through genetic algorithms, and finally the specific absorption range of each photovoltaic area is determined.

[0027] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and the computer program is used to execute the above method.

[0028] According to another aspect of an embodiment of the present invention, an electronic device is provided, comprising:

[0029] processor;

[0030] a memory for storing instructions executable by the processor;

[0031] The processor is configured to read the executable instructions from the memory and execute the instructions to implement the above method.

[0032] Therefore, the present invention first provides a calculation process for the voltage change at the distribution network node after the photovoltaic power source is connected. Then, using a method combining the Pearson correlation coefficient and the cosine distance, the specific absorption range of each photovoltaic area is analyzed by comprehensively considering two types of data: voltage drop and photovoltaic output time. Finally, a specific calculation process for the line loss of the low-voltage distribution network after the absorption range of the photovoltaic area is delineated is provided. Thus, the variation pattern of the line node voltage after the photovoltaic power source is connected to the distribution network is clarified, the accuracy of the division of the absorption range of the photovoltaic area is improved, and data support is provided for the study of theoretical line loss in photovoltaic areas. The consistency between the line loss rate calculated by the proposed method and the actual theoretical line loss rate is proved, and the accuracy of the line loss rate calculation of the photovoltaic area is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0034] Figure 1 1 is a flow chart of a method for calculating line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss, provided by an exemplary embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of a low-voltage distribution network containing photovoltaic power sources provided by an exemplary embodiment of the present invention;

[0036] Figure 3 This is a flow chart for calculating line loss rate of a low-voltage distribution network including photovoltaic power sources provided by an exemplary embodiment of the present invention;

[0037] Figure 4 It is a structural schematic diagram of a device for calculating line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss, provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0038] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0039] It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0040] Those skilled in the art will understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0041] It should also be understood that, in the embodiments of the present invention, “a plurality of” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[0042] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0043] In addition, the term "and / or" in this invention merely describes an association relationship between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Furthermore, the character " / " in this invention generally indicates that the related objects are in an "or" relationship.

[0044] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced with each other. For the sake of brevity, they will not be described one by one.

[0045] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0046] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0047] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0048] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0049] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, and servers, and can operate in conjunction with numerous other general-purpose or specialized computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments, and / or configurations suitable for use with terminal devices, computer systems, servers, and other electronic devices include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, minicomputer systems, mainframe computer systems, and distributed cloud computing technology environments including any of the above.

[0050] Electronic devices such as terminal devices, computer systems, and servers can be described in the general context of computer system-executable instructions (such as program modules) executed by a computer system. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked via a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media, including storage devices.

[0051] Exemplary Methods

[0052] Figure 1 The figure shows a flow chart of the method for calculating line loss rate of a low-voltage distribution network containing photovoltaic power based on voltage loss provided by the present invention. Figure 1 As shown in the figure, the calculation method of line loss rate of low-voltage distribution network containing photovoltaic power source based on voltage loss includes:

[0053] S1: Perform matrix transformation on the power flow equation of the low-voltage distribution network after accessing the photovoltaic power source, introduce the sensitivity factor, and use the sensitivity factor and the injected active power ΔP j and reactive power ΔQ j The relationship between the two factors is used to calculate the change in the voltage at the distribution network node after the photovoltaic power source is connected, where the sensitivity factor represents the influence of the active / reactive output of the photovoltaic power source on the node voltage amplitude / phase angle.

[0054] In the embodiment of the present invention, according to the Jacobian matrix of the power system flow, the power flow calculation in the active distribution network (ADNs) system satisfies the following equation:

[0055]

[0056] Where Δθ and ΔU represent the changes in line node voltage and amplitude after the photovoltaic power source is connected; ΔP = |ΔP PV -ΔP L | and ΔQ = |ΔQ PV -ΔQ L | respectively represent the changes in active power and reactive power after the node is injected with photovoltaic power, where ΔP PV , ΔQ PV Indicates the change of photovoltaic active and reactive power output, ΔP L , ΔQ L Represents the change of load active and reactive power; constitutes the element A in the Jacobi matrix Pθ 、B PU 、C Qθ and D Qθ They represent the relationship between the injected power fluctuation (ΔP, ΔQ) and the node voltage (amplitude and phase angle), respectively.

[0057] After matrix transformation of formula (1), we can get:

[0058]

[0059] S Pθ 、S PU 、S QU and S Qθ It is defined as a sensitivity factor, which represents the impact of the active / reactive output of the photovoltaic power source on the node voltage amplitude / phase angle. It can be concluded that the relationship between the voltage change ΔU of the distribution network containing N PQ nodes and the changes in active power and reactive power ΔP and ΔQ is:

[0060] ΔU=S PU ΔP+S QU ΔQ (3)

[0061] Where, ΔP=[ΔP1,ΔP2,...,ΔP N ] T , ΔQ=[ΔQ1,ΔQ2,...,ΔQ N ] T In practice, the regulation of ΔP and ΔQ is also related to the power factor of the photovoltaic power generation unit, namely:

[0062]

[0063] Where S max is the maximum capacity of the photovoltaic inverter, cosφ max is the maximum power factor of the photovoltaic inverter.

[0064] When the number of connected photovoltaic nodes is N pvWhen the voltage of node i is affected by its own voltage, it is also affected by the active power ΔP injected by other nodes. j and reactive power ΔQ j impact.

[0065]

[0066] in, It represents the voltage of node i when no photovoltaic power source is added. and They are matrices S PU and S QU The (i, j)th element of is . In a distribution network containing PV power sources, PV nodes are usually considered PQ nodes, and the PV power source has a unity power factor, that is, ΔQ = 0. Therefore, in different PV power source access ADNs schemes, after obtaining ΔP, the voltage change can be calculated according to Equation (3), and then the node voltage can be calculated according to Equation (5), and the voltage change ΔU can be calculated according to Equation (6).

[0067]

[0068] S2: Using a method combining the Pearson correlation coefficient and cosine distance, the specific absorption range of each PV area is analyzed based on two types of data: voltage drop and PV output time.

[0069] Optionally, a method combining the Pearson correlation coefficient and the cosine distance is used to analyze the specific absorption range of each photovoltaic substation based on two types of data: voltage drop and photovoltaic output time, including: acquiring data, wherein the data includes a statistical table of substation line losses, details of users' daily electricity consumption, voltage curve data, current curve data, power factor curve, power curve data, the relationship between transformers and meter boxes, and the relationship between meter boxes and meters; based on the acquired data, the neighboring users of photovoltaic users are determined by using a voltage drop method or a correlation method of photovoltaic output time; users with abnormal current and voltage are eliminated based on time-sharing and phase-sharing voltage, current, power and neighboring users, the absorption range is designed as an optimization problem under multiple constraints, the absorption users are determined by a genetic algorithm, and finally the specific absorption range of each photovoltaic substation is determined.

[0070] In this embodiment of the present invention, the data required includes a statistical table of line losses in the substation area, detailed daily electricity consumption of users, voltage curve data, current curve data, power factor curve data, power curve data, the relationship between transformers and meter boxes, and the relationship between meter boxes and meters. Demarcation of the PV substation's consumption area first requires determining the neighboring users of PV users. There are two methods for identifying neighboring users of PV users: the voltage drop method and the correlation method based on the PV output moment.

[0071] Optionally, the voltage drop method is used to determine the neighboring users of the photovoltaic user, including: judging the relative position of each user under the substation and the assessment table from the voltage perspective, thereby judging the neighboring users of the photovoltaic user.

[0072] In the embodiment of the present invention, the voltage drop method is specifically as follows: due to the large proportion of missing GIS coordinate information, it is impossible to use GIS spatial distance to calculate adjacent users. The relative position of each user under the substation and the assessment table is mainly judged from the voltage perspective (the average of the evening peak voltage for multiple days), so as to judge the users nearby the power generation household.

[0073] Optionally, the correlation method of photovoltaic output time is used to determine the neighboring users of photovoltaic users, including: determining the photovoltaic output time according to the change pattern of the current curve of the grid-connected meter at the photovoltaic output time and the non-output time; analyzing the multi-day voltage curves of the substation power meter and the ordinary user meter at the photovoltaic output time, and using a method combining the Pearson correlation coefficient method and the cosine distance method to perform correlation and distance calculation on the voltage curve of the user under the substation and the voltage curve of the substation power meter, and using the results of the two methods of correlation and distance calculation to perform comprehensive weighting and sorting to determine the neighboring users of the photovoltaic user.

[0074] In an embodiment of the present invention, the correlation method of the photovoltaic output time is specifically as follows: the photovoltaic output time is determined based on the change pattern of the current curve of the grid meter at the photovoltaic output time and the non-output time (generally within 8:00 to 18:00, determined according to the current curve). The identification method for each power generation user and each phase of adjacent users: analyze the voltage curves of the substation power meter (grid meter) and the ordinary user meter for multiple days (7 days) at the photovoltaic output time, and use the Pearson correlation coefficient method combined with the cosine distance method to calculate the correlation and distance between the voltage curve of the user under the substation and the voltage curve of the substation power meter, and use the results of the two methods to perform comprehensive weighting and sorting to determine the adjacent users of the power meter. The specific calculation formula is as follows:

[0075] 1) The calculation formula of Pearson correlation coefficient is as follows:

[0076]

[0077] E(X) represents the mathematical expectation of X, which is represented by the mean of sample X. X is the 96-point voltage data [x1, x2, ..., x 96 ], Y is the 96-point voltage data of the power meter [y1,y2,…,y 96 ].

[0078] 2) Cosine distance, also known as cosine similarity, measures the similarity between two vectors using the cosine value of the angle between them. The calculation formula is as follows:

[0079]

[0080] Finally, the results of the two methods are comprehensively weighted to calculate the comprehensive correlation between each ordinary user and each power meter, and then the neighboring users of each power meter are determined according to the comprehensive correlation ranking.

[0081] Therefore, the neighboring users of photovoltaic users are comprehensively determined through the voltage flow drop method and the voltage correlation at the time of photovoltaic output. Based on multi-dimensional data such as time-sharing and phase-sharing voltage, current, power, and neighboring users, users with abnormal current and voltage are eliminated. The absorption range is designed as an optimization problem under multiple constraints. The absorption users are determined through genetic algorithms, and the photovoltaic absorption range is finally determined. This provides support for splitting photovoltaic substations according to the absorption range and performing voltage drop calculations. The specific implementation method is as follows:

[0082] (1) Linear programming: Linear programming is the study of how to maximize (minimize) a linear objective function under multiple constraints (expressed as linear equations or inequalities). The objective function and constraints of a linear programming problem are both linear functions; the constraints are denoted as st (i.e., subject to). According to classical linear programming theory, a general linear programming problem can be written in the following standard form:

[0083]

[0084] Among them, x j are the decision variables of linear programming (such as power, voltage, current and user comprehensive correlation, etc.), is the objective function (minimizing the difference between the amount of electricity connected to the grid and the amount of electricity consumed), and st is the constraint condition (constraints such as electricity, voltage, and current).

[0085] (2) Genetic Algorithm: Genetic algorithm is a random global search and optimization method developed by imitating the biological evolution mechanism in nature. Its essence is an efficient, parallel, global search method that can automatically acquire and accumulate knowledge about the search space during the search process and adaptively control the search process to obtain the optimal solution. In the absorption area division scheme, the neighboring photovoltaic absorption users are all candidate solutions to the problem. According to the calculation steps of the genetic algorithm, the optimal user that meets the linear programming constraints is calculated as the final absorption user, completing the absorption area division.

[0086] Genetic algorithm calculation steps: 1) Initialize the chromosome population (randomly select a group of neighboring users as candidate solutions; the candidate solutions to the problem are represented by chromosomes, and an initial population representing the set of potential solutions to the problem is generated); 2) Evaluate and obtain the fitness value of each chromosome (candidate solution) in the population (use the fitness level of each individual in the population to guide the search, and the fitness is obtained by converting the objective function value); 3) Select parents based on the fitness value (following the principle that the higher the fitness, the greater the selection probability, select two chromosome individuals from the population as the father and mother); 4) Perform genetic operations on the parent chromosomes to produce offspring (cut off a certain position of the two chromosomes and splice them together to generate a new chromosome; that is, mix the two feasible solution spaces with the highest fitness); 5) Evaluate the new chromosome and replace the parent chromosome according to a certain principle to form a new generation population; 6) If the stopping condition (the allowable error range of the objective function) is met, stop the calculation and return the best chromosome (the solution to the problem); otherwise, repeat the calculation on the new generation population.

[0087] S3: Based on the basic archival data of the marketing system, the voltage curve of the total meter of the procurement system, the voltage, current, power factor curve of low-voltage users and the daily load power data, the active substation is divided into multiple passive substations according to the specific absorption range. The theoretical loss power of each passive substation after the split is calculated separately by measuring the pressure difference loss between the substation head end and each user according to the proportional relationship between the substation voltage loss percentage and the power loss percentage. The theoretical line loss of the active substation is obtained by cumulative calculation.

[0088] In the embodiment of the present invention, Figure 2 Take a low-voltage distribution network as an example, where the head end is a transformer, G is a photovoltaic user, R is the line resistance, I is the current, and P is the user load power. Assume that the absorption range of photovoltaic G is R4 and R n-1 If there are n-4 users in total, the PV area is divided into two equivalent areas according to the consumption range, and then the two voltage difference losses are calculated separately. After dividing the PV consumption range, the theoretical line loss calculation method is as follows:

[0089]

[0090] The calculation process of the pressure drop method is as follows:

[0091] (1) Voltage drop of transformer supply at the first end:

[0092]

[0093] (2) Photovoltaic supply voltage drop:

[0094]

[0095] (3) Power loss of voltage drop algorithm:

[0096]

[0097] Deviation between theoretical power loss and power loss by voltage drop method:

[0098]

[0099] If all users within the photovoltaic consumption range consume photovoltaic power, then At this time, ΔP = 0. Therefore, if the accurate absorption range is obtained with photovoltaic users as the center, the voltage difference loss of the photovoltaic area and the photovoltaic area is superimposed by splitting the equivalent area, which is equal to the actual theoretical line loss.

[0100] This embodiment describes the application of the present invention to the theoretical line loss calculation of photovoltaic power generation areas, which is used to tap the potential of loss reduction in low-voltage areas. Figure 3 As shown in the figure, it mainly includes the process of photovoltaic area node voltage analysis, data collection, absorption range analysis, voltage drop method to calculate line loss, etc.

[0101] In specific implementation, the impact was analyzed by calculating the change in voltage at distribution network nodes after PV power was connected. The Pearson correlation coefficient and cosine distance were then used to analyze the correlation between PV output time. Taking both voltage drop and PV output time into account, a genetic algorithm was employed to analyze the specific absorption range of each PV substation. Finally, after defining the absorption range of the PV substation, the theoretical line losses of the low-voltage PV substation were calculated according to the principle of equivalent substation splitting.

[0102] When implementing the algorithm, the requirements of accuracy and universality are comprehensively considered. Only by collecting system voltage, current, power factor curve and meter access phase information, the theoretical line loss calculation of low-voltage photovoltaic stations can be accurately realized, which has the value of universal promotion and application.

[0103] Thus, the present invention proposes the following key points:

[0104] (1) Calculation method of node voltage in distribution network when photovoltaic power generation is connected

[0105] By performing matrix transformation on the power flow equation of the low-voltage distribution network after connecting to the photovoltaic power source, a sensitivity factor is introduced, which represents the impact of the active / reactive output of the photovoltaic power source on the node voltage amplitude / phase angle. When the number of connected photovoltaic nodes is determined, the node voltage is affected not only by its own voltage, but also by the active power ΔP injected by other nodes. j and reactive power ΔQ j In different photovoltaic access distribution network schemes, the sensitivity factor and the injected active power ΔP j and reactive power ΔQ j The node voltage is calculated based on the relationship between them.

[0106] (2) Method for dividing photovoltaic power consumption areas

[0107] The voltage flow drop method and voltage correlation at the time of photovoltaic output are used to comprehensively determine the neighboring users of photovoltaic users. Based on multi-dimensional data such as time-sharing and phase-sharing voltage, current, power, and neighboring users, users with abnormal current and voltage are eliminated. The absorption range is designed as an optimization problem under multiple constraints. The absorption users are determined through genetic algorithms, and the photovoltaic absorption range is ultimately determined. This provides support for splitting photovoltaic substations according to the absorption range and performing voltage drop calculations.

[0108] (3) Calculation model for line loss rate of low-voltage distribution network including photovoltaic power supply

[0109] The line loss calculation method of the low-voltage distribution network containing photovoltaic power sources using the voltage drop method is based on the basic archival data of the marketing system (station-user relationship, meter phase, etc.), the total meter voltage curve of the procurement system, the voltage, current, power factor curve of the low-voltage user and the daily load power data. By identifying the power consumption range of photovoltaic grid-connected users, the active substation is split into multiple passive substations. After the split, the theoretical power loss of each passive substation is calculated separately according to the proportional relationship between the voltage loss percentage and the power loss percentage of the substation, through the easily measurable pressure difference loss between the substation head end and each user. Finally, the theoretical line loss of the active substation is obtained by cumulative calculation.

[0110] This paper uses voltage analysis to clarify the variation patterns of node voltage. By analyzing the node voltage changes after photovoltaic power sources are connected to the low-voltage distribution network, a method is proposed to calculate the node voltage change based on the node active power change. This method clarifies the variation patterns of line node voltage after photovoltaic power sources are connected to the distribution network, providing theoretical support for the next step of demarcating the photovoltaic power consumption range and accurately calculating the line loss rate.

[0111] This method uses correlation coefficient analysis to identify the photovoltaic power supply absorption range. By collecting and analyzing data on voltage drop and photovoltaic output time, using the Pearson correlation coefficient and cosine distance, combined with linear programming and genetic algorithms, it improves the accuracy of photovoltaic power supply absorption range division, solving the problem of accurately dividing the photovoltaic power supply absorption range in active low-voltage distribution networks.

[0112] This paper uses a voltage loss method to accurately calculate the line loss rate in photovoltaic substations. By dividing the photovoltaic absorption range of the active distribution network, a voltage loss-based method for calculating the line loss rate in low-voltage active distribution networks is proposed. The consistency between the line loss rate calculated by the proposed method and the actual theoretical line loss rate is demonstrated, improving the accuracy of the line loss rate calculation in photovoltaic substations. This method utilizes big data methods to address the problem of large errors in line loss rate calculation in low-voltage photovoltaic substations due to incomplete system data.

[0113] In summary, the present invention first provides a calculation process for the voltage change at the distribution network node after the photovoltaic power source is connected. It then uses a method combining the Pearson correlation coefficient and the cosine distance to comprehensively consider two types of data: voltage drop and photovoltaic output time. It then analyzes the specific absorption range of each photovoltaic area. Finally, it provides a specific calculation process for the line loss of the low-voltage distribution network after the absorption range of the photovoltaic area is defined. This clarifies the variation pattern of the line node voltage after the photovoltaic power source is connected to the distribution network, improves the accuracy of the division of the absorption range of the photovoltaic area, and provides data support for the study of theoretical line loss in photovoltaic areas. It also proves the consistency between the line loss rate calculated by the proposed method and the actual theoretical line loss rate, thereby improving the accuracy of the line loss rate calculation in photovoltaic areas.

[0114] Exemplary devices

[0115] Figure 4 This is a schematic diagram of a device for calculating line loss rate of a low-voltage distribution network containing photovoltaic power based on voltage loss, provided by an exemplary embodiment of the present invention. Figure 4 As shown, the voltage loss-based line loss rate calculation device for a low-voltage distribution network containing photovoltaic power sources proposed in this embodiment includes:

[0116] The voltage change calculation module is used to perform matrix transformation on the low-voltage distribution network power flow equation after the photovoltaic power source is connected, introduce the sensitivity factor, and use the sensitivity factor and the injected active power ΔP j and reactive power ΔQ j The relationship between the two factors is used to calculate the change in the voltage at the distribution network node after the photovoltaic power source is connected, wherein the sensitivity factor represents the influence of the active / reactive output of the photovoltaic power source on the node voltage amplitude / phase angle;

[0117] The absorption range determination module is used to analyze the specific absorption range of each photovoltaic area based on two types of data: voltage drop and photovoltaic output time, using a method combining the Pearson correlation coefficient and cosine distance;

[0118] The loss rate calculation module is used to split the active substation into multiple passive substations according to the specific absorption range based on the basic archival data of the marketing system, the voltage curve of the total meter of the procurement system, the voltage, current, power factor curve of the low-voltage users and the daily load power data. After the split, the theoretical loss power of each passive substation is calculated separately according to the proportional relationship between the voltage loss percentage and the power loss percentage of the substation by measuring the pressure difference loss between the substation head end and each user, and the theoretical line loss of the active substation is obtained by cumulative calculation.

[0119] Optionally, the absorption range determination module is specifically configured to:

[0120] Acquire data, wherein the data includes a statistical table of line losses in the substation area, details of daily power consumption of users, voltage curve data, current curve data, power factor curve data, power curve data, the relationship between the transformer and the meter box, and the relationship between the meter box and the meter;

[0121] Based on the acquired data, the neighboring users of the photovoltaic user are determined using the voltage drop method or the correlation method of the photovoltaic output time;

[0122] Based on the time-sharing and phase-sharing voltage, current, power and neighboring users, users with abnormal current and voltage are eliminated, and the absorption range is designed as an optimization problem under multiple constraints. The absorption users are determined through genetic algorithms, and finally the specific absorption range of each photovoltaic area is determined.

[0123] The device for calculating line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss according to an embodiment of the present invention corresponds to the method for calculating line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss according to another embodiment of the present invention, and will not be repeated here.

[0124] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A method for calculating line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss, characterized in that: include: The matrix transformation of the low-voltage distribution network power flow equation after accessing the photovoltaic power source is carried out, the sensitivity factor is introduced, and the sensitivity factor and the injected active power ΔP are used to calculate the power flow equation. j and reactive power ΔQ j The relationship between the two factors is used to calculate the change in the voltage at the distribution network node after the photovoltaic power source is connected, wherein the sensitivity factor represents the influence of the active or reactive output of the photovoltaic power source on the node voltage amplitude or phase angle; Analyze the specific absorption range of each photovoltaic area based on voltage drop data, or analyze the specific absorption range of each photovoltaic area based on photovoltaic output time data using a combination of Pearson correlation coefficient and cosine distance; Based on the basic archival data of the marketing system, the voltage curve of the total meter of the procurement system, the voltage, current, power factor curve of low-voltage users and the daily load power data, the active substation is divided into multiple passive substations according to the specific absorption range. The theoretical loss power of each passive substation after the split is calculated separately by measuring the pressure difference loss between the substation head end and each user according to the proportional relationship between the substation voltage loss percentage and the power loss percentage, and the theoretical line loss of the active substation is obtained by cumulative calculation.

2. The method according to claim 1, characterized in that Based on the voltage drop data, the specific absorption range of each photovoltaic area is analyzed. Alternatively, based on the photovoltaic output time data, the specific absorption range of each photovoltaic area is analyzed using a method combining the Pearson correlation coefficient and cosine distance, including: Acquire data, wherein the data includes a statistical table of line losses in the substation area, details of daily power consumption of users, voltage curve data, current curve data, power factor curve data, power curve data, the relationship between the transformer and the meter box, and the relationship between the meter box and the meter; Based on the acquired data, the neighboring users of the photovoltaic user are determined based on the voltage drop data, or based on the photovoltaic output time data, the neighboring users of the photovoltaic user are determined by combining the Pearson correlation coefficient and the cosine distance method; Based on the time-sharing and phase-sharing voltage, current, power and neighboring users, users with abnormal current and voltage are eliminated, and the absorption range is designed as an optimization problem under multiple constraints. The absorption users are determined through genetic algorithms, and finally the specific absorption range of each photovoltaic area is determined.

3. The method according to claim 2, characterized in that Based on voltage drop data, determine the neighboring users of photovoltaic users, including: Determine the relative position of each user in the substation and the assessment table from the voltage perspective, and thus determine the neighboring users of the photovoltaic user.

4. The method according to claim 2, characterized in that Based on the photovoltaic output data, a method combining the Pearson correlation coefficient and cosine distance is used, including: Determine the photovoltaic output time based on the changing pattern of the current curve of the grid meter at the time of photovoltaic output and the time of no output; The multi-day voltage curves of the power generation meters in the substation and the ordinary user meters at the time of photovoltaic output were analyzed. The Pearson correlation coefficient method was combined with the cosine distance method to calculate the correlation and distance between the voltage curves of the users under the substation and the voltage curves of the power generation meters in the substation. The results of the two methods of correlation and distance calculation were comprehensively weighted and sorted to determine the neighboring users of the photovoltaic users.

5. A device for calculating line loss rate of a low-voltage distribution network containing photovoltaic power sources based on voltage loss, characterized in that: include: The voltage change calculation module is used to perform matrix transformation on the low-voltage distribution network power flow equation after the photovoltaic power source is connected, introduce the sensitivity factor, and use the sensitivity factor and the injected active power ΔP j and reactive power ΔQ j The relationship between the two factors is used to calculate the change in the voltage at the distribution network node after the photovoltaic power source is connected, wherein the sensitivity factor represents the influence of the active or reactive output of the photovoltaic power source on the node voltage amplitude or phase angle; The absorption range determination module is used to analyze the specific absorption range of each photovoltaic area based on voltage drop data, or to analyze the specific absorption range of each photovoltaic area based on photovoltaic output time data using a combination of Pearson correlation coefficient and cosine distance; The loss rate calculation module is used to split the active substation into multiple passive substations according to the specific absorption range based on the basic archival data of the marketing system, the voltage curve of the total meter of the procurement system, the voltage, current, power factor curve of the low-voltage users and the daily load power data. After the split, the theoretical loss power of each passive substation is calculated separately according to the proportional relationship between the voltage loss percentage and the power loss percentage of the substation by measuring the pressure difference loss between the substation head end and each user, and the theoretical line loss of the active substation is obtained by cumulative calculation.

6. The device according to claim 5, characterized in that The absorption range determination module is specifically used for: Acquire data, wherein the data includes a statistical table of line losses in the substation area, details of daily power consumption of users, voltage curve data, current curve data, power factor curve data, power curve data, the relationship between the transformer and the meter box, and the relationship between the meter box and the meter; Based on the acquired data, the neighboring users of the photovoltaic user are determined based on the voltage drop data, or based on the photovoltaic output time data, the neighboring users of the photovoltaic user are determined by combining the Pearson correlation coefficient and the cosine distance method; Based on the time-sharing and phase-sharing voltage, current, power and neighboring users, users with abnormal current and voltage are eliminated, and the absorption range is designed as an optimization problem under multiple constraints. The absorption users are determined through genetic algorithms, and finally the specific absorption range of each photovoltaic area is determined.

7. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 4.

8. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1 to 4.

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