Three-phase unbalanced power flow line loss analysis method, system, equipment and medium

Abstract

The present invention discloses a method for analyzing line losses in a three-phase unbalanced power flow, comprising: establishing a power flow model for a three-phase unbalanced system based on a sequence component method; the power flow model includes admittance matrices corresponding to positive, negative, and zero sequences, respectively, and equivalent admittances corresponding to any two of the positive, negative, and zero sequences; transforming the power flow model to determine a first relationship between coupled positive-sequence current, equivalent admittance, and uncoupled positive-sequence current, and a second relationship between coupled negative-sequence current, equivalent admittance, and uncoupled negative-sequence current; determining the positive-sequence electrical component based on the first relationship, and determining the negative-sequence electrical component based on the second relationship; and determining the line loss of the three-phase unbalanced system based on the positive-sequence electrical component and the negative-sequence electrical component. The method provided by this application can improve the accuracy of line loss analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method, system, equipment and medium for analyzing line losses of three-phase unbalanced power flows. Background Art

[0002] In modern power systems, three-phase imbalance is primarily caused by factors such as uneven load distribution, equipment failure, and asymmetric access to distributed generation resources. This can lead to reduced system stability, degraded electromagnetic equipment performance, increased power loss, shortened equipment life, and malfunctioning protective devices. In extreme cases, it can even trigger system failures. Accurate calculation and analysis of three-phase unbalanced power flows is crucial for analyzing line losses and maintaining grid stability, power quality, and operational efficiency.

[0003] Traditionally, three-phase unbalanced power flow calculations are based on the phase component method and the sequence component method. The sequence component method decomposes the three-phase unbalanced system into three subsystems: positive sequence, negative sequence, and zero sequence. This method simplifies the calculation process by solving these subsystems independently, making it suitable for symmetrical fault analysis and highly efficient.

[0004] However, the volatility, uncertainty and possible asymmetric access of distributed energy in modern power systems have aggravated the three-phase imbalance problem in distribution networks, affecting the accuracy of three-phase unbalanced power flow line loss analysis. Summary of the Invention

[0005] In view of this, the present invention provides a three-phase unbalanced power flow line loss analysis method, system, equipment and medium, which solves the technical problem that the volatility, uncertainty and possible asymmetric access of distributed energy in modern power systems exacerbate the three-phase imbalance problem of the distribution network and affect the accuracy of three-phase unbalanced power flow line loss analysis.

[0006] A first aspect of the present invention provides a three-phase unbalanced power flow line loss analysis method, comprising:

[0007] Based on the sequence component method, a power flow model of the three-phase unbalanced system is established; the power flow model includes admittance matrices corresponding to the positive sequence, negative sequence and zero sequence, respectively, and the equivalent admittance corresponding to any two sequences among the positive sequence, the negative sequence and the zero sequence;

[0008] Converting the power flow model to determine a first relationship between the coupled positive-sequence current, the equivalent admittance, and the uncoupled positive-sequence current, and a second relationship between the coupled negative-sequence current, the equivalent admittance, and the uncoupled negative-sequence current;

[0009] A positive-sequence electrical component is determined according to the first relationship, and a negative-sequence electrical component is determined according to the second relationship; and a line loss of the three-phase unbalanced system is determined according to the positive-sequence electrical component and the negative-sequence electrical component.

[0010] Preferably, the positive-sequence electrical component includes an uncoupled positive-sequence current, a branch positive-sequence current, and an uncoupled positive-sequence voltage; and determining the positive-sequence electrical component according to the first relationship includes:

[0011] Obtaining a coupled positive-sequence voltage, a coupled negative-sequence voltage, and a coupled zero-sequence voltage corresponding to each node in the three-phase unbalanced system;

[0012] determining the uncoupled positive-sequence current of each of the nodes according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage, and the first relationship;

[0013] Determining the branch positive sequence current corresponding to each of the nodes according to the uncoupled positive sequence current of each of the nodes and the uncoupled positive sequence current corresponding to the branch between the nodes;

[0014] The uncoupled positive sequence voltage is determined according to the branch positive sequence current corresponding to each node, the uncoupled positive sequence voltage and the admittance matrix corresponding to the positive sequence.

[0015] Preferably, the negative-sequence electrical component includes uncoupled negative-sequence current, branch negative-sequence current and uncoupled negative-sequence voltage;

[0016] Determining the negative-sequence electrical component according to the second relationship includes:

[0017] Obtain the negative-sequence reference voltage of the three-phase unbalanced system, as well as the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node;

[0018] determining the uncoupled negative-sequence current of each of the nodes according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage, and the second relationship;

[0019] Determining the branch negative-sequence current corresponding to each of the nodes according to the uncoupled negative-sequence current of each of the nodes and the uncoupled negative-sequence current corresponding to the branch between the nodes;

[0020] The uncoupled negative-sequence voltage is determined according to the branch negative-sequence current corresponding to each node, the negative-sequence reference voltage, and the admittance matrix corresponding to the negative sequence.

[0021] Preferably, the positive-sequence electrical component includes a branch positive-sequence current, and the negative-sequence electrical component includes a branch negative-sequence current;

[0022] Determining the line loss of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component includes:

[0023] Determine a first ratio between the square of the branch positive sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the positive sequence of each node;

[0024] Determine a second ratio between the square of the branch negative-sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the negative-sequence current of each node;

[0025] A line loss of the three-phase unbalanced system is determined according to the sum of the first ratio and the second ratio.

[0026] Preferably, the method further comprises:

[0027] determining the active power of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component;

[0028] The line loss rate is determined according to a ratio of the active power of the three-phase unbalanced system to the line loss.

[0029] Preferably, the positive-sequence electrical component includes an uncoupled positive-sequence current and an uncoupled positive-sequence voltage, and the negative-sequence electrical component includes an uncoupled negative-sequence current and an uncoupled negative-sequence voltage;

[0030] The determining the active power of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component includes:

[0031] Determining the active power of the balancing node according to the uncoupled positive-sequence current, the uncoupled positive-sequence voltage, the uncoupled negative-sequence current, and the uncoupled negative-sequence voltage corresponding to the balancing node in the three-phase unbalanced system;

[0032] Determining the active power of the PV node according to the uncoupled positive-sequence current, uncoupled positive-sequence voltage, uncoupled negative-sequence current, and uncoupled negative-sequence voltage corresponding to the PV node in the three-phase unbalanced system;

[0033] The active power of the three-phase unbalanced system is determined according to the active power of the balancing node and the active power of the PV node.

[0034] Preferably, the method further comprises:

[0035] Converting the power flow model to determine a third relationship between the coupled zero-sequence current, the equivalent admittance, and the uncoupled zero-sequence current;

[0036] Obtain the coupled positive sequence voltage, coupled negative sequence voltage and coupled zero sequence voltage corresponding to each node in the three-phase unbalanced system;

[0037] determining the uncoupled zero-sequence current of each of the nodes according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage, and the third relationship;

[0038] determining an uncoupled zero-sequence voltage at each of the nodes according to the uncoupled zero-sequence current and the third relationship;

[0039] determining a positive-sequence power according to the uncoupled positive-sequence voltage and the uncoupled positive-sequence current;

[0040] determining negative-sequence power according to the uncoupled negative-sequence voltage and the uncoupled negative-sequence current;

[0041] determining zero-sequence power according to the coupled zero-sequence voltage and the coupled zero-sequence current;

[0042] A line loss rate is determined according to the positive-sequence power, the negative-sequence power, the zero-sequence power, and the active power of the three-phase unbalanced system.

[0043] In a second aspect, the present invention further provides a three-phase unbalanced power flow line loss analysis system, comprising:

[0044] A sequence component module is used to establish a power flow model of a three-phase unbalanced system based on a sequence component method; the power flow model includes admittance matrices corresponding to positive sequence, negative sequence, and zero sequence, respectively, and an equivalent admittance corresponding to any two of the positive sequence, the negative sequence, and the zero sequence;

[0045] a power flow conversion module, configured to convert the power flow model to determine a first relationship between the coupled positive sequence current, the equivalent admittance, and the uncoupled positive sequence current, and a second relationship between the coupled negative sequence current, the equivalent admittance, and the uncoupled negative sequence current;

[0046] A line loss analysis module is configured to determine a positive-sequence electrical component according to the first relationship, determine a negative-sequence electrical component according to the second relationship, and determine a line loss of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component.

[0047] In a third aspect, the present invention further provides an electronic device comprising a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the processor executes the steps of the three-phase unbalanced power flow line loss analysis method as described in the first aspect.

[0048] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed, implements the steps of the three-phase unbalanced power flow line loss analysis method as described in the first aspect.

[0049] It can be seen from the above technical solution that the present invention establishes a power flow model of a three-phase unbalanced system based on a sequence component method; the power flow model includes admittance matrices corresponding to positive sequence, negative sequence and zero sequence, respectively, and equivalent admittances corresponding to any two sequences among the positive sequence, negative sequence and zero sequence; the power flow model is transformed to determine a first relationship between the coupled positive sequence current, the equivalent admittance and the uncoupled positive sequence current, and a second relationship between the coupled negative sequence current, the equivalent admittance and the uncoupled negative sequence current; the positive sequence electrical component is determined according to the first relationship, and the negative sequence electrical component is determined according to the second relationship; and the line loss of the three-phase unbalanced system is determined according to the positive sequence electrical component and the negative sequence electrical component. In the present invention, the established power flow model includes the equivalent admittance corresponding to any two sequences among the positive sequence, negative sequence and zero sequence, that is, the mutual coupling between the sequence components is taken into account when establishing the power flow model; the mutual coupling of the sequence components is taken into account when determining the positive sequence electrical component, the negative sequence electrical component and the zero sequence electrical component based on the power flow model, so that the mutual coupling between the sequence components can be removed during the calculation process, which can improve the accuracy of the determined positive sequence electrical component, the negative sequence electrical component and the zero sequence electrical component, thereby improving the accuracy of determining the line loss of the three-phase unbalanced system. Moreover, the three-phase unbalanced power flow line loss analysis method provided in this embodiment takes into account the mutual coupling between the sequence components, and can be applied to a dynamic operating power grid environment with widespread access to distributed power generation resources and frequent fluctuations in load conditions, and has higher applicability. In addition, this embodiment is calculated based on the power flow model of the three-phase unbalanced system, and the calculation process is simple, which can reduce the consumption of computing power. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0051] Figure 1 is a schematic structural diagram of a computer device in one embodiment;

[0052] Figure 2 1. A schematic flow chart of the steps of a three-phase unbalanced power flow line loss analysis method according to an embodiment;

[0053] Figure 3 is a schematic flow chart of the steps of determining the positive sequence electrical component according to the first relationship in another embodiment;

[0054] Figure 4 is a schematic flow chart of the steps of determining the negative-sequence electrical component according to the second relationship in another embodiment;

[0055] Figure 5 A schematic flow chart of steps for determining line loss of a three-phase unbalanced system based on positive-sequence electrical components and negative-sequence electrical components in another embodiment;

[0056] Figure 6 A schematic flow chart of the steps for calculating line loss rate in another embodiment;

[0057] Figure 7 FIG1 is a flow chart of steps for determining the active power of a three-phase unbalanced system in another embodiment;

[0058] Figure 8 A schematic flow chart of the steps for calculating line loss rate in another embodiment;

[0059] Figure 9 Schematic diagram of the structure of a three-phase unbalanced power flow line loss analysis system in another embodiment;

[0060] Figure 10 FIG. 1 is a schematic structural diagram of an electronic device in an embodiment. DETAILED DESCRIPTION

[0061] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0062] First of all, before specifically introducing the technical solutions of the embodiments disclosed in this application, the background technology or technological evolution context on which the embodiments of this application are based is introduced. In modern power systems, the three-phase imbalance phenomenon is mainly caused by factors such as uneven distribution of loads, equipment failures, and asymmetric access to distributed power generation resources. As a result, the stability of the power system may be reduced, the performance of electromagnetic equipment may be degraded, power loss may be increased, the life of the equipment may be shortened, and protection devices may malfunction. In extreme cases, system failures may even be triggered. Accurate calculation and analysis of three-phase unbalanced power flows is crucial for determining the line loss of the three-phase unbalanced system, maintaining grid stability, power quality, and operational efficiency.

[0063] Currently, the calculation of three-phase unbalanced power flows is primarily based on the phase component method and the sequence component method. The phase component method directly models and solves phases A, B, and C, making it suitable for analyzing three-phase unbalanced power grids and various asymmetric operating conditions. However, it is computationally intensive in large-scale, complex systems. The sequence component method decomposes the three-phase unbalanced system into positive-sequence, negative-sequence, and zero-sequence subsystems, simplifying the calculation process by independently solving them. It is suitable for symmetrical fault analysis and offers high computational efficiency.

[0064] However, with the widespread integration of distributed energy resources, such as photovoltaics, wind power, and small hydropower, the operational complexity of distribution networks has increased significantly. The volatility, uncertainty, and potential asymmetric integration of distributed energy resources exacerbate three-phase imbalance in distribution networks, impacting the accuracy of three-phase unbalanced power flow calculations, power quality, and increased line losses, which in turn impacts the economics and reliability of the power system. Conventional technologies have employed advanced computational methods, with a particular focus on phase and sequence component methods. These computational methods can more accurately simulate the actual operating state of the power grid, particularly considering three-phase imbalance and the integration of distributed energy resources. Furthermore, by introducing more sophisticated and complex mathematical models, optimization algorithms, and machine learning techniques, the accuracy and practicality of the sequence component method in analyzing three-phase unbalanced power flows have been improved. However, while these advanced computational methods improve computational accuracy, they also increase computer power consumption. Insufficient computing resources are a major concern, particularly when dealing with large-scale power grids and highly complex systems. Therefore, while improving the accuracy of three-phase unbalanced power flow calculations, reducing computing power consumption is an inevitable trend. To this end, the present application provides a method for analyzing line losses in three-phase unbalanced power flows.

[0065] The three-phase unbalanced power flow line loss analysis method provided in the embodiment of the present application can be applied to Figure 1 The computer device shown in FIG. The computer device includes a processor, memory, a communication interface, a display, and an input device connected via a system bus. The processor of the computer device provides computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The communication interface of the computer device is used to communicate with external terminals via wired or wireless communication. Wireless communication can be achieved via Wi-Fi, mobile cellular networks, NFC (near-field communication), or other technologies. When executed by the processor, the computer program implements a three-phase unbalanced power flow line loss analysis method. The display of the computer device can be a liquid crystal display or an electronic ink display. The input device of the computer device can be a touch screen covering the display, keys, a trackball, or a touchpad provided on the computer device housing, or an external keyboard, touchpad, or mouse.

[0066] Those skilled in the art will understand that Figure 1 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0067] The following describes in detail the technical solution of the present application and how the technical solution of the present application solves the technical problem with specific embodiments.

[0068] like Figure 2 As shown, the embodiment of the present application provides a three-phase unbalanced power flow line loss analysis method. This embodiment uses the method applied to a computer device as an example. In this embodiment, the method includes the following steps:

[0069] Step S100: Based on the sequence component method, a power flow model of the three-phase unbalanced system is established; the power flow model includes admittance matrices corresponding to positive sequence, negative sequence and zero sequence, and equivalent admittances corresponding to any two sequences among the positive sequence, negative sequence and zero sequence.

[0070] The sequence component method, based on the principle of linear superposition, decomposes an asymmetric three-phase electrical quantity (such as voltage and current) into three symmetrical sequence components: positive, negative, and zero. Using this method, a computer converts the voltage equations at each node in the three-phase unbalanced system into symmetrical components, forming a power flow model.

[0071] Specifically, the power flow model can be expressed as: ,in, They represent the positive sequence component, negative sequence component and zero sequence component of the node injection current respectively, Represent the positive sequence component, negative sequence component and zero sequence component of the node voltage respectively, is the admittance matrix, the diagonal elements of the admittance matrix Represent the admittance matrices corresponding to positive sequence, negative sequence and zero sequence respectively, and the off-diagonal elements of the admittance matrix , represents the equivalent admittance between sequence x and sequence Y due to the coupling of sequence components. For example: represents the corresponding equivalent admittance between positive sequence and negative sequence, represents the equivalent admittance between the negative sequence and zero sequence. Where, both I and U components are vectors of length n, where n is the number of nodes.

[0072] Step S200: converting the power flow model to determine a first relationship between the coupled positive sequence current, equivalent admittance and the uncoupled positive sequence current, and a second relationship between the coupled negative sequence current, equivalent admittance and the uncoupled negative sequence current.

[0073] After determining the power flow model, the computer device expands the power flow model and performs conversion to obtain the first relational expression and the second relational expression.

[0074] The first relationship expresses the correspondence between coupled positive-sequence current, equivalent admittance, and uncoupled positive-sequence current. The coupled positive-sequence current refers to the positive-sequence current injected at each node when the sequence components are mutually coupled. The uncoupled positive-sequence current refers to the actual positive-sequence current injected when the sequence components are mutually coupled, that is, the positive-sequence current injected at each node after removing the effects of mutual coupling. Expanding the power flow model reveals the relationship between the current and voltage associated with the positive-sequence component, as well as their interaction with the equivalent admittance. This relationship facilitates further analysis of the behavior of the positive-sequence component in three-phase unbalanced systems.

[0075] The second relationship expresses the correspondence between coupled negative-sequence current, equivalent admittance, and uncoupled negative-sequence current. Coupled negative-sequence current refers to the negative-sequence current injected at each node when the sequence components are mutually coupled. Uncoupled negative-sequence current refers to the actual negative-sequence current injected when the sequence components are mutually coupled, i.e., the negative-sequence current injected at each node after removing the effects of mutual coupling. Expanding the power flow model reveals the relationship between the current and voltage associated with the negative-sequence component, as well as their interaction with the equivalent admittance. This relationship also facilitates in-depth analysis of the behavior of negative-sequence components in three-phase unbalanced systems.

[0076] Specifically, after expanding the power flow model, we can get the formula , transforming the formula yields ,in, Represent the coupled positive sequence current, coupled negative sequence current and coupled zero sequence current respectively, They represent uncoupled positive sequence current, uncoupled negative sequence current and uncoupled zero sequence current respectively.

[0077] Step S300: determining the positive-sequence electrical component according to the first relational expression, determining the negative-sequence electrical component according to the second relational expression; and determining the line loss of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component.

[0078] After determining the first relationship, the computer device solves for the positive-sequence electrical component of the three-phase unbalanced system based on the first relationship. The positive-sequence electrical component may include uncoupled positive-sequence current, branch positive-sequence current, uncoupled positive-sequence voltage, and positive-sequence power. Uncoupled positive-sequence voltage refers to the positive-sequence voltage at each node, taking into account the mutual coupling between sequence components. Branch positive-sequence current refers to the positive-sequence current corresponding to the branches connecting each node in the three-phase unbalanced system.

[0079] After determining the second relationship, the computer device solves for the negative-sequence electrical component of the three-phase unbalanced system based on the second relationship. The negative-sequence electrical component may include uncoupled negative-sequence current, branch negative-sequence current, uncoupled positive-sequence voltage, and negative-sequence power. Uncoupled negative-sequence voltage refers to the negative-sequence voltage at each node, taking into account the mutual coupling between sequence components. Branch negative-sequence current refers to the negative-sequence current corresponding to the branches connecting each node in the three-phase unbalanced system.

[0080] After determining the positive-sequence and negative-sequence electrical components, the computer device can analyze the line loss of the three-phase unbalanced system based on these components. Specifically, the computer device uses these components to calculate the power loss of each branch in the three-phase unbalanced system. Power loss refers to the energy lost during current transmission due to components such as resistance, inductance, and capacitance. By calculating the power loss of each branch, the computer device can determine the total power loss of the entire three-phase unbalanced system, or line loss.

[0081] It should be noted that an embodiment of the present application provides a three-phase unbalanced power flow line loss analysis method, which establishes a power flow model of a three-phase unbalanced system based on a sequence component method; the power flow model includes admittance matrices corresponding to positive sequence, negative sequence and zero sequence, respectively, and equivalent admittances corresponding to any two sequences among the positive sequence, negative sequence and zero sequence; the power flow model is transformed to determine a first relationship between the coupled positive sequence current, the equivalent admittance and the uncoupled positive sequence current, and a second relationship between the coupled negative sequence current, the equivalent admittance and the uncoupled negative sequence current; the positive sequence electrical component is determined according to the first relationship, and the negative sequence electrical component is determined according to the second relationship; the line loss of the three-phase unbalanced system is determined according to the positive sequence electrical component and the negative sequence electrical component.

[0082] In this embodiment, the established power flow model includes the equivalent admittance corresponding to any two sequences among the positive sequence, negative sequence, and zero sequence, that is, the mutual coupling between the sequence components is taken into account when establishing the power flow model; the mutual coupling of the sequence components is taken into account when determining the positive sequence electrical component, the negative sequence electrical component, and the zero sequence electrical component based on the power flow model. In this way, the mutual coupling between the sequence components can be removed during the calculation process, which can improve the accuracy of the determined positive sequence electrical component, the negative sequence electrical component, and the zero sequence electrical component, thereby improving the accuracy of determining the line loss of the three-phase unbalanced system. In addition, the three-phase unbalanced power flow line loss analysis method provided by this embodiment takes into account the mutual coupling between the sequence components, and can be applied to a dynamic operating power grid environment with widespread access to distributed power generation resources and frequent fluctuations in load conditions, and has higher applicability. In addition, this embodiment is calculated based on the power flow model of the three-phase unbalanced system, and the calculation process is simple, which can reduce the consumption of computing power.

[0083] In some embodiments, the positive sequence electrical component includes uncoupled positive sequence current, branch positive sequence current, and uncoupled positive sequence voltage. Figure 3 As shown, an implementation method of determining the positive sequence electrical component according to the first relationship is involved, and the steps of the implementation method include:

[0084] Step S301: Acquire the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node in the three-phase unbalanced system.

[0085] The coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node in the three-phase unbalanced system may be known in advance and stored in a memory of a computer device. During the calculation process, they may be directly retrieved from the memory when needed.

[0086] In an optional embodiment, the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node in the three-phase unbalanced system may be directly measured.

[0087] Step S302: Determine the uncoupled positive-sequence current of each node according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage, and the first relationship.

[0088] The computer device can obtain the uncoupled positive sequence current of each node according to the obtained coupled positive sequence voltage, coupled negative sequence voltage and coupled zero sequence voltage and the first relational expression.

[0089] In an optional embodiment, the computer device may first determine the coupled positive-sequence current of each node based on the coupled positive-sequence voltage, the coupled negative-sequence voltage and the coupled zero-sequence voltage, and then determine the uncoupled positive-sequence current of each node based on the coupled positive-sequence current and the first relationship.

[0090] Specifically, the coupled positive sequence current flowing into node i can be expressed as:

[0091] ,in, where represents the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage at each node, respectively. branch_i represents the number of branches connected to node i. Substituting the obtained coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage into the above formula yields the coupled positive-sequence current flowing into node i.

[0092] The uncoupled positive sequence current flowing into node i can be expressed as: , the uncoupled positive-sequence current flowing into node i can be obtained by substituting the coupled positive-sequence current, coupled negative-sequence voltage and coupled zero-sequence voltage flowing into node i.

[0093] Step S303 : determining the branch positive sequence current corresponding to each node according to the uncoupled positive sequence current of each node and the uncoupled positive sequence current corresponding to the branch between each node.

[0094] The computer device obtains the coupled positive sequence current corresponding to each branch between each node, and determines the branch positive sequence current corresponding to the branch between each node according to the coupled positive sequence current and the determined uncoupled positive sequence current.

[0095] In an optional embodiment, the computer device can arbitrarily select a node from all nodes of the three-phase unbalanced system as the first node, and determine the branch positive-sequence current corresponding to the first node based on the uncoupled positive-sequence current of the first node and the coupled positive-sequence current corresponding to each branch connected to the first node; by repeating this process, the branch positive-sequence current corresponding to all nodes of the three-phase unbalanced system can be obtained.

[0096] Specifically, the branch positive sequence current between node i and node j can be expressed as , branch_j represents the number of branches between node i and node j. By solving this formula, the positive sequence current of the branch corresponding to each node i can be obtained.

[0097] Step S304 : determining the uncoupled positive sequence voltage according to the branch positive sequence current corresponding to each node, the uncoupled positive sequence voltage, and the admittance matrix corresponding to the positive sequence.

[0098] The computer device obtains the branch positive sequence current corresponding to each node and can obtain the uncoupled positive sequence voltage according to the branch positive sequence current, the coupled positive sequence voltage and the admittance matrix corresponding to the positive sequence.

[0099] Specifically, assuming that node i is a balanced node, for other nodes j in the three-phase unbalanced system, according to , the uncoupled positive sequence voltage of other nodes can be expressed as: .in, is the voltage drop, I is the current, R is the resistance, and Y is the admittance.

[0100] In this embodiment, by obtaining the coupled positive-sequence voltage, coupled negative-sequence voltage and coupled zero-sequence voltage corresponding to each node in the three-phase unbalanced system, as well as the first relationship, the uncoupled positive-sequence current, branch positive-sequence current and uncoupled positive-sequence voltage in the positive-sequence electrical component can be determined. This method of determining the positive-sequence electrical component is simple and easy to implement, which can reduce the consumption of computing power, thereby improving the efficiency of the three-phase unbalanced line loss analysis method.

[0101] In one embodiment, the negative sequence electrical component includes uncoupled negative sequence current, branch negative sequence current and uncoupled negative sequence voltage; in this case, Figure 4As shown, an implementation method of determining the negative sequence electrical component according to the second relationship is involved, and the steps of the implementation method include:

[0102] Step S311: Obtain the negative-sequence reference voltage of the three-phase unbalanced system, and the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node.

[0103] The computer device can use the potential at the balance node as a negative sequence reference voltage. Specifically, the negative sequence reference voltage can be expressed as: ,in, represents the negative sequence voltage at the balance node, represents the negative sequence current at the balancing node, The description of the coupled positive-sequence voltage, coupled negative-sequence voltage and coupled zero-sequence voltage corresponding to each node can refer to the specific description of the above embodiment, which will not be repeated here.

[0104] The computer device obtains the negative-sequence reference voltage of the three-phase unbalanced system, as well as the coupled positive-sequence voltage, coupled negative-sequence voltage and coupled zero-sequence voltage corresponding to each node.

[0105] Step S312: Determine the uncoupled negative-sequence current of each node according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage, and the second relationship.

[0106] The computer device can determine the uncoupled negative sequence current of each node according to the acquired negative sequence reference voltage, coupled positive sequence voltage, coupled negative sequence voltage and coupled zero sequence voltage, as well as the second relationship.

[0107] In an optional embodiment, the computer device may first determine the coupled negative-sequence current of each node based on the coupled positive-sequence voltage, the coupled negative-sequence voltage, and the coupled zero-sequence voltage, and then determine the uncoupled negative-sequence current of each node based on the coupled negative-sequence current and the second relationship.

[0108] Specifically, the coupled negative sequence current flowing into node i can be expressed as:

[0109] , substituting the obtained coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage into the formula can obtain the coupled negative-sequence current flowing into node i.

[0110] The uncoupled negative sequence current flowing into node i can be expressed as: , the uncoupled negative-sequence current flowing into node i can be obtained by substituting the coupled negative-sequence current, coupled positive-sequence voltage and coupled zero-sequence voltage flowing into node i.

[0111] Step S313: Determine the branch negative sequence current corresponding to each node according to the uncoupled negative sequence current of each node and the uncoupled negative sequence current corresponding to the branch between each node.

[0112] The computer device obtains the coupled negative-sequence current corresponding to each branch between each node, and determines the branch negative-sequence current corresponding to each node based on the coupled negative-sequence current and the determined uncoupled negative-sequence current.

[0113] In an optional embodiment, the computer device can arbitrarily select a node from all nodes of the three-phase unbalanced system as the first node, and determine the branch negative-sequence current corresponding to the first node based on the uncoupled negative-sequence current of the first node and the coupled negative-sequence current corresponding to each branch connected to the first node; by repeating this process, the branch negative-sequence current corresponding to all nodes of the three-phase unbalanced system can be obtained.

[0114] Specifically, the branch negative sequence current between node i and node j can be expressed as , branch_j represents the number of branches between node i and node j. By solving this formula, the negative-sequence current of the branch corresponding to each node i can be obtained.

[0115] Step S314: Determine the uncoupled negative sequence voltage according to the branch negative sequence current corresponding to each node, the negative sequence reference voltage and the admittance matrix corresponding to the negative sequence.

[0116] The computer device obtains the branch negative sequence current corresponding to each node, and can obtain the uncoupled negative sequence voltage according to the branch negative sequence current, the coupled negative sequence voltage and the admittance matrix corresponding to the negative sequence.

[0117] Specifically, assuming that node i is a balanced node, for other nodes j in the three-phase unbalanced system, according to , the negative sequence voltage of other nodes can be expressed as: .

[0118] In this embodiment, by obtaining the negative-sequence reference voltage in the three-phase unbalanced system, as well as the coupled positive-sequence voltage, coupled negative-sequence voltage and coupled zero-sequence voltage corresponding to each node, and the second relationship, the uncoupled negative-sequence current, branch negative-sequence current and uncoupled negative-sequence voltage in the negative-sequence electrical component can be determined. This method of determining the negative-sequence electrical component is simple and easy to implement, which can reduce the consumption of computing power, thereby improving the efficiency of the three-phase unbalanced line loss analysis method.

[0119] In some embodiments, the positive-sequence electrical component includes the branch positive-sequence current, and the negative-sequence electrical component includes the branch negative-sequence current; in this case, Figure 5 As shown, an implementation method for determining the line loss of a three-phase unbalanced system based on positive-sequence electrical components and negative-sequence electrical components includes the following steps:

[0120] Step S321: Determine a first ratio between the square of the branch positive sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the positive sequence of each node.

[0121] After obtaining the branch positive sequence current of each node in the three-phase unbalanced system, the computer device determines the square of the positive sequence current of each branch, calculates the ratio between the square and the admittance matrix corresponding to the positive sequence of each node, and obtains a first ratio.

[0122] Step S322: Determine a second ratio between the square of the branch negative-sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the negative sequence of each node.

[0123] After obtaining the branch negative sequence current of each node in the three-phase unbalanced system, the computer device determines the square of the negative sequence current of each branch, calculates the ratio between the balance and the admittance matrix corresponding to the negative sequence of each node, and obtains a second ratio.

[0124] Step S323: Determine the line loss of the three-phase unbalanced system according to the sum of the first ratio and the second ratio.

[0125] After obtaining the first ratio and the second ratio, the computer device determines the line loss of the three-phase unbalanced system according to the first ratio and the second ratio.

[0126] Specifically, the line loss of a three-phase unbalanced system can be expressed as: .

[0127] In an optional embodiment, the three-phase electrical parameters of the three-phase unbalanced system during actual operation, namely, the currents of phases A, B, and C, can be expressed as:

[0128]

[0129] in, is the phase angle parameter, Due to the phase characteristics of the positive-sequence, negative-sequence, and zero-sequence networks, line losses are only generated in the positive-sequence and negative-sequence networks. The line losses of the three-phase unbalanced system can be expressed as:

[0130]

[0131] In this embodiment, the mutual coupling of the sequence components is considered when determining the branch positive-sequence current and branch negative-sequence current at each node in the three-phase unbalanced system. This improves the accuracy of the obtained branch positive-sequence current and branch negative-sequence current, thereby improving the accuracy of the line loss of the three-phase unbalanced system determined by the branch positive-sequence current and branch negative-sequence current. Furthermore, as can be seen from the above formula, this application introduces a mathematical model with a time variable in the process of calculating line loss, enabling power flow calculation when phase changes exist in the power system.

[0132] In one embodiment, Figure 6 As shown, the method further comprises the steps of:

[0133] Step S401: Determine the active power of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component.

[0134] The active power of the three-phase unbalanced system may refer to the active power output by the generator in the power grid. The computer device may determine the active power of the three-phase unbalanced system based on the determined positive-sequence electrical component and negative-sequence electrical component.

[0135] Among them, the positive sequence electrical component includes uncoupled positive sequence current and uncoupled positive sequence voltage, and the negative sequence electrical component includes uncoupled negative sequence current and uncoupled negative sequence voltage; in this case, if Figure 7 As shown, an implementation method for determining the active power of a three-phase unbalanced system based on a positive-sequence electrical component and a negative-sequence electrical component is provided, and the steps of the implementation method include:

[0136] Step S4011: Determine the active power of the balanced node according to the uncoupled positive sequence current, uncoupled positive sequence voltage, uncoupled negative sequence current, and uncoupled negative sequence voltage corresponding to the balanced node in the three-phase unbalanced system.

[0137] The computer device obtains the uncoupled positive-sequence current and uncoupled positive-sequence voltage corresponding to the balancing node according to the obtained positive-sequence electrical component, and obtains the uncoupled negative-sequence current and uncoupled negative-sequence voltage corresponding to the balancing node according to the obtained negative-sequence electrical component.

[0138] The computer device can determine the positive-sequence active power corresponding to the balancing node through the uncoupled positive-sequence current and uncoupled positive-sequence voltage corresponding to the balancing node, and can determine the negative-sequence active power corresponding to the balancing node through the uncoupled negative-sequence current and uncoupled negative-sequence voltage corresponding to the balancing node; the active power of the balancing node is determined by calculating the sum of the positive-sequence active power corresponding to the balancing node and the negative-sequence active power corresponding to the balancing node.

[0139] Specifically, the active power of the balancing node can be expressed as ,in, represents the active power of the balancing node, represents the uncoupled positive sequence voltage at the balancing node, represents the uncoupled positive sequence current at the balancing node, represents the uncoupled negative sequence voltage at the balancing node, Represents the uncoupled negative sequence current at the balancing node.

[0140] Step S4012: Determine the active power of the PV node according to the uncoupled positive-sequence current, uncoupled positive-sequence voltage, uncoupled negative-sequence current, and uncoupled negative-sequence voltage corresponding to the PV node in the three-phase unbalanced system.

[0141] A PV node is a node where the active power P and voltage amplitude V are given, while the reactive power Q and voltage phase angle δ are the desired quantities. In power systems, a PV node typically represents a generator node with some reactive power regulation capability or a substation node with reactive power compensation equipment.

[0142] The computer device obtains the uncoupled positive-sequence current and the uncoupled positive-sequence voltage corresponding to the PV node according to the obtained positive-sequence electrical component, and obtains the uncoupled negative-sequence current and the uncoupled negative-sequence voltage corresponding to the PV node according to the obtained negative-sequence electrical component.

[0143] The computer device can determine the positive-sequence active power corresponding to the PV node through the uncoupled positive-sequence current and uncoupled positive-sequence voltage corresponding to the PV node, and can determine the negative-sequence active power corresponding to the PV node through the uncoupled negative-sequence current and uncoupled negative-sequence voltage corresponding to the PV node; and the active power of the PV node is determined by calculating the sum of the positive-sequence active power and the negative-sequence active power corresponding to the PV node.

[0144] Specifically, the active power of the PV node can be expressed as ,in, Indicates the active power of the PV node, Table k-th PV node uncoupled positive sequence voltage, represents the uncoupled positive sequence current of the kth PV node, represents the uncoupled negative sequence voltage at the kth PV node, represents the uncoupled negative sequence current of the PV node, and n_PV represents the number of PV nodes.

[0145] Step S4013: Determine the active power of the three-phase unbalanced system according to the active power of the balanced node and the active power of the PV node.

[0146] The computer device determines the active power of the balancing node and the active power of the PV node. By calculating the sum of the active power of the balancing node and the active power of the PV node, the active power of the three-phase unbalanced system can be determined. Specifically, the active power of the three-phase unbalanced system can be expressed as: .

[0147] The above embodiment determines the active power of the three-phase unbalanced system by determining the active power of the balanced nodes and the active power of the PV nodes in the three-phase unbalanced system. This method of determining the active power of the three-phase unbalanced system is fast and easy to implement, can reduce the consumption of computing power, and thus can improve the efficiency of determining the active power of the three-phase unbalanced system.

[0148] Step S402: Determine the line loss rate according to the ratio of active power to line loss of the three-phase unbalanced system.

[0149] The line loss rate refers to the percentage of electrical energy lost in a line during power transmission compared to the power supply. After determining the positive-sequence electrical component, negative-sequence electrical component, and line loss of a three-phase unbalanced system, the computer device can determine the line loss rate of the three-phase unbalanced system based on these positive-sequence electrical components, negative-sequence electrical components, and line loss. Specifically, the computer device can determine the power supply of the three-phase unbalanced system based on the positive-sequence electrical component and the negative-sequence electrical component; and determine the line loss rate based on the ratio of the line loss to the power supply.

[0150] After determining the active power of the three-phase unbalanced system, the computer device calculates the ratio of the active power to the line loss, and multiplies the ratio by 100% to obtain the line loss rate. Specifically, the line loss rate can be expressed as: .

[0151] In this embodiment, the active power of the three-phase unbalanced system is determined based on the positive-sequence electrical component and the negative-sequence electrical component. The line loss rate is determined based on the ratio of the active power of the three-phase unbalanced system to the line loss. Determining the active power of the three-phase unbalanced system using the positive-sequence electrical component and the negative-sequence electrical component, which are determined while taking into account the mutual coupling between the sequence components, can improve the accuracy of the determined active power of the three-phase unbalanced system, and thus improve the accuracy of the determined line loss rate.

[0152] In some embodiments, as Figure 8 As shown, the method further includes:

[0153] Step S501: convert the power flow model to determine a third relationship between the coupled zero-sequence current, the equivalent admittance, and the uncoupled zero-sequence current.

[0154] After determining the power flow model, the computer device expands and transforms the power flow model to obtain the third equation. The third equation represents the corresponding relationship between the coupled zero-sequence current, the equivalent admittance, and the uncoupled zero-sequence current. The coupled zero-sequence current refers to the zero-sequence injection current at each node when the sequence components are mutually coupled. The uncoupled zero-sequence current refers to the actual zero-sequence injection current when the sequence components are mutually coupled, that is, the zero-sequence injection current at each node after removing the influence of the mutual coupling. After expanding the power flow model, the equivalent admittance can be obtained. This equivalent admittance represents the ratio between the zero-sequence injection current and the zero-sequence voltage when the sequence components are mutually coupled.

[0155] After determining the third relationship, the computer device solves for the zero-sequence electrical components of the three-phase unbalanced system based on the third relationship. The zero-sequence electrical components may include uncoupled zero-sequence current, uncoupled zero-sequence voltage, and zero-sequence power. The uncoupled zero-sequence voltage refers to the zero-sequence voltage at each node, taking into account the mutual coupling between sequence components.

[0156] Step S502: Acquire the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node in the three-phase unbalanced system.

[0157] The computer device can obtain the uncoupled zero-sequence current of each node based on the acquired coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage. For a description of the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node, reference can be made to the detailed description of the above embodiment and will not be repeated here.

[0158] Step S503: Determine the uncoupled zero-sequence current of each node according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage, and the third relationship.

[0159] The computer device can determine the uncoupled zero-sequence current of each node according to the acquired coupled positive-sequence voltage, coupled negative-sequence voltage, coupled zero-sequence voltage, and the third relationship.

[0160] In an optional embodiment, the computer device may first determine the coupled positive-sequence current of each node based on the coupled positive-sequence voltage, the coupled negative-sequence voltage and the coupled zero-sequence voltage, and then determine the uncoupled zero-sequence current of each node based on the coupled zero-sequence current and a third relationship.

[0161] Specifically, the coupled zero-sequence current flowing into node i can be expressed as:

[0162] , substituting the obtained coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage into the formula can obtain the coupled zero-sequence current flowing into node i.

[0163] The uncoupled zero-sequence current flowing into node i can be expressed as: , the uncoupled zero-sequence current flowing into node i can be obtained by substituting the coupled zero-sequence current, coupled negative-sequence voltage and coupled zero-sequence voltage flowing into node i.

[0164] Step S504: Determine the uncoupled zero-sequence voltage of each node according to the uncoupled zero-sequence current and the third relationship.

[0165] After obtaining the uncoupled zero-sequence current, the computer device can determine the uncoupled zero-sequence voltage of each node according to the third relationship and the uncoupled zero-sequence current.

[0166] Specifically, the uncoupled zero-sequence voltage at node i can be expressed as: .

[0167] In this embodiment, the uncoupled zero-sequence current at each node is determined by obtaining the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node in the three-phase unbalanced system, along with the third relationship. Furthermore, the uncoupled zero-sequence voltage at each node is determined based on the uncoupled zero-sequence current and the power flow model. This method for determining the zero-sequence electrical component is simple and easy to implement, reducing computing power consumption and thus improving the efficiency of the three-phase unbalanced line loss analysis method.

[0168] Step S505 : Determine the positive-sequence power according to the uncoupled positive-sequence voltage and the uncoupled positive-sequence current.

[0169] The computer device can determine the positive sequence power by determining the product of the uncoupled positive sequence current and the conjugate of the uncoupled positive sequence voltage. Specifically, the positive sequence power flowing into the node i can be expressed as .

[0170] Step S506: Determine the negative-sequence power according to the uncoupled negative-sequence voltage and the uncoupled negative-sequence current.

[0171] The computer device can determine the negative sequence power by determining the product of the uncoupled negative sequence current and the conjugate of the uncoupled negative sequence voltage. Specifically, the negative sequence power flowing into node i can be expressed as .

[0172] Step S507: Determine the zero-sequence power according to the coupled zero-sequence voltage and the coupled zero-sequence current.

[0173] The computer device can determine the zero-sequence power by determining the product of the uncoupled zero-sequence current and the conjugate of the uncoupled zero-sequence voltage. Specifically, the zero-sequence power flowing into node i can be expressed as .

[0174] In this embodiment, the positive-sequence power can be determined by determining the uncoupled positive-sequence voltage and uncoupled positive-sequence current in the positive-sequence electrical component; the negative-sequence power can be determined by determining the uncoupled negative-sequence voltage and uncoupled negative-sequence current in the negative-sequence electrical component; and the zero-sequence power can be determined by determining the uncoupled zero-sequence voltage and uncoupled zero-sequence current in the zero-sequence electrical component. The determination of the positive-sequence electrical component, the negative-sequence electrical component, and the zero-sequence electrical component takes into account the mutual coupling between the sequence components, thereby improving the accuracy of the determination of the positive-sequence power, the negative-sequence power, and the zero-sequence power.

[0175] In this embodiment, the positive-sequence power can be determined by determining the uncoupled positive-sequence voltage and uncoupled positive-sequence current in the positive-sequence electrical component; the negative-sequence power can be determined by determining the uncoupled negative-sequence voltage and uncoupled negative-sequence current in the negative-sequence electrical component; and the zero-sequence power can be determined by determining the uncoupled zero-sequence voltage and uncoupled zero-sequence current in the zero-sequence electrical component. The determination of the positive-sequence electrical component, the negative-sequence electrical component, and the zero-sequence electrical component takes into account the mutual coupling between the sequence components, thereby improving the accuracy of the determination of the positive-sequence power, the negative-sequence power, and the zero-sequence power.

[0176] Step S508: Determine the line loss rate according to the positive-sequence power, negative-sequence power, zero-sequence power, and the active power of the three-phase unbalanced system.

[0177] After obtaining the positive-sequence power, negative-sequence power, and zero-sequence power, the computer device determines the sum of the positive-sequence power, negative-sequence power, and zero-sequence power corresponding to each node; calculates the third ratio of the sum to the active power of the three-phase unbalanced system; and calculates the difference between 1 and the third ratio and multiplies the difference by 100% to obtain the line loss rate. Specifically, the line loss rate can be expressed as: .

[0178] Based on the same inventive concept, an embodiment of the present application further provides a three-phase unbalanced power flow line loss analysis system for implementing the above-mentioned three-phase unbalanced power flow line loss analysis method.

[0179] The implementation solution provided by the system to solve the problem is similar to the implementation solution described in the above method. Therefore, the specific limitations in one or more three-phase unbalanced power flow line loss analysis system embodiments provided below can refer to the limitations of the three-phase unbalanced power flow line loss analysis method above and will not be repeated here.

[0180] like Figure 9 As shown, the embodiment of the present application provides a three-phase unbalanced power flow line loss analysis system, including:

[0181] The sequence component module 100 is used to establish a power flow model of the three-phase unbalanced system based on the sequence component method; the power flow model includes the admittance matrices corresponding to the positive sequence, negative sequence and zero sequence, and the equivalent admittance corresponding to any two sequences among the positive sequence, negative sequence and zero sequence;

[0182] The power flow conversion module 200 is used to convert the power flow model to determine a first relationship between the coupled positive sequence current, the equivalent admittance and the uncoupled positive sequence current, and a second relationship between the coupled negative sequence current, the equivalent admittance and the uncoupled negative sequence current;

[0183] The line loss analysis module 300 is configured to determine the positive sequence electrical component according to the first relationship, determine the negative sequence electrical component according to the second relationship, and determine the line loss of the three-phase unbalanced system according to the positive sequence electrical component and the negative sequence electrical component.

[0184] In some embodiments, the positive-sequence electrical component includes an uncoupled positive-sequence current, a branch positive-sequence current, and an uncoupled positive-sequence voltage; the line loss analysis module 300 is configured to:

[0185] Obtain the coupled positive sequence voltage, coupled negative sequence voltage and coupled zero sequence voltage corresponding to each node in the three-phase unbalanced system;

[0186] Determine the uncoupled positive sequence current of each node according to the coupled positive sequence voltage, the coupled negative sequence voltage, the coupled zero sequence voltage and the first relationship;

[0187] Determine the branch positive sequence current corresponding to each node according to the uncoupled positive sequence current of each node and the uncoupled positive sequence current corresponding to the branch between each node;

[0188] The uncoupled positive sequence voltage is determined according to the branch positive sequence current, uncoupled positive sequence voltage and the admittance matrix corresponding to the positive sequence corresponding to each node.

[0189] In some embodiments, the negative-sequence electrical component includes an uncoupled negative-sequence current, a branch negative-sequence current, and an uncoupled negative-sequence voltage;

[0190] The line loss analysis module 300 is used to:

[0191] Obtain the negative-sequence reference voltage of the three-phase unbalanced system, as well as the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node;

[0192] Determine the uncoupled negative sequence current of each node according to the coupled positive sequence voltage, the coupled negative sequence voltage, the coupled zero sequence voltage, and the second relationship;

[0193] Determine the branch negative sequence current corresponding to each node according to the uncoupled negative sequence current of each node and the uncoupled negative sequence current corresponding to the branch between each node;

[0194] The uncoupled negative sequence voltage is determined according to the branch negative sequence current corresponding to each node, the negative sequence reference voltage and the admittance matrix corresponding to the negative sequence.

[0195] In some embodiments, the positive-sequence electrical component includes a branch positive-sequence current, and the negative-sequence electrical component includes a branch negative-sequence current;

[0196] The line loss analysis module 300 is used to:

[0197] Determine a first ratio between the square of the branch positive sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the positive sequence of each node;

[0198] Determine a second ratio between the square of the branch negative sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the negative sequence of each node;

[0199] The line loss of the three-phase unbalanced system is determined according to the sum of the first ratio and the second ratio.

[0200] In some embodiments, the system further includes: a first line loss rate calculation module, configured to:

[0201] A power calculation module for determining the active power of the three-phase unbalanced system based on the positive-sequence electrical component and the negative-sequence electrical component;

[0202] The line loss rate calculation submodule is used to determine the line loss rate according to the ratio of active power to line loss in the three-phase unbalanced system.

[0203] In some embodiments, the positive-sequence electrical component includes an uncoupled positive-sequence current and an uncoupled positive-sequence voltage, and the negative-sequence electrical component includes an uncoupled negative-sequence current and an uncoupled negative-sequence voltage;

[0204] Power calculation module for:

[0205] Determine the active power of the balancing node according to the uncoupled positive sequence current, uncoupled positive sequence voltage, uncoupled negative sequence current and uncoupled negative sequence voltage corresponding to the balancing node in the three-phase unbalanced system;

[0206] Determine the active power of the PV node based on the uncoupled positive sequence current, uncoupled positive sequence voltage, uncoupled negative sequence current, and uncoupled negative sequence voltage corresponding to the PV node in the three-phase unbalanced system;

[0207] The active power of the three-phase unbalanced system is determined based on the active power of the balanced node and the active power of the PV node.

[0208] In some embodiments, the system further includes: a second line loss rate calculation module, configured to:

[0209] Transform the power flow model to determine the third relationship between the coupled zero-sequence current, the equivalent admittance and the uncoupled zero-sequence current;

[0210] Obtain the coupled positive sequence voltage, coupled negative sequence voltage and coupled zero sequence voltage corresponding to each node in the three-phase unbalanced system;

[0211] Determine the uncoupled zero-sequence current of each node according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage and the third relationship;

[0212] Determine the uncoupled zero-sequence voltage of each node according to the uncoupled zero-sequence current and the third relationship;

[0213] Determine the positive sequence power based on the uncoupled positive sequence voltage and the uncoupled positive sequence current;

[0214] Determine the negative sequence power based on the uncoupled negative sequence voltage and the uncoupled negative sequence current;

[0215] Determine the zero-sequence power according to the coupled zero-sequence voltage and the coupled zero-sequence current;

[0216] The line loss rate is determined based on the positive-sequence power, negative-sequence power, zero-sequence power and the active power of the three-phase unbalanced system.

[0217] like Figure 10 As shown, an embodiment of the present application provides an electronic device, the electronic device 10 includes a memory 20 and a processor 30, the memory 20 stores a computer program, and when the computer program is executed by the processor 30, the processor 30 executes the steps of the three-phase unbalanced power flow line loss analysis method in the above embodiment.

[0218] An embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed, the steps of the three-phase unbalanced power flow line loss analysis method in the above embodiment are implemented.

[0219] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described systems, electronic devices, and computer storage media can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0220] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0221] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0222] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, electronic devices, computer storage media and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0223] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0224] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0225] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the method described in each embodiment of the present invention via a computer device (which can be a personal computer, server, or network device, etc.). The aforementioned storage medium includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0226] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A three-phase unbalanced power flow line loss analysis method, characterized in that: include: Based on the sequence component method, a power flow model of the three-phase unbalanced system is established; the power flow model includes admittance matrices corresponding to the positive sequence, negative sequence and zero sequence, respectively, and the equivalent admittance corresponding to any two sequences among the positive sequence, the negative sequence and the zero sequence; Converting the power flow model to determine a first relationship between the coupled positive-sequence current, the equivalent admittance, and the uncoupled positive-sequence current, and a second relationship between the coupled negative-sequence current, the equivalent admittance, and the uncoupled negative-sequence current; determining a positive-sequence electrical component according to the first relational expression, determining a negative-sequence electrical component according to the second relational expression; and determining a line loss of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component; The positive-sequence electrical component includes the branch positive-sequence current, and the negative-sequence electrical component includes the branch negative-sequence current; Determining the line loss of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component includes: Determine a first ratio between the square of the branch positive sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the positive sequence of each node; Determine a second ratio between the square of the branch negative-sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the negative-sequence current of each node; A line loss of the three-phase unbalanced system is determined according to the sum of the first ratio and the second ratio.

2. The three-phase unbalanced power flow line loss analysis method according to claim 1, characterized in that: The positive-sequence electrical component includes uncoupled positive-sequence current, branch positive-sequence current, and uncoupled positive-sequence voltage; and determining the positive-sequence electrical component according to the first relationship includes: Obtaining a coupled positive-sequence voltage, a coupled negative-sequence voltage, and a coupled zero-sequence voltage corresponding to each node in the three-phase unbalanced system; determining the uncoupled positive-sequence current of each of the nodes according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage, and the first relationship; Determining the branch positive sequence current corresponding to each of the nodes according to the uncoupled positive sequence current of each of the nodes and the uncoupled positive sequence current corresponding to the branch between the nodes; The uncoupled positive sequence voltage is determined according to the branch positive sequence current corresponding to each node, the uncoupled positive sequence voltage and the admittance matrix corresponding to the positive sequence.

3. The three-phase unbalanced power flow line loss analysis method according to claim 1, characterized in that: The negative sequence electrical component includes uncoupled negative sequence current, branch negative sequence current and uncoupled negative sequence voltage; Determining the negative-sequence electrical component according to the second relationship includes: Obtain the negative-sequence reference voltage of the three-phase unbalanced system, as well as the coupled positive-sequence voltage, coupled negative-sequence voltage, and coupled zero-sequence voltage corresponding to each node; determining the uncoupled negative-sequence current of each of the nodes according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage, and the second relationship; Determining the branch negative-sequence current corresponding to each of the nodes according to the uncoupled negative-sequence current of each of the nodes and the uncoupled negative-sequence current corresponding to the branch between the nodes; The uncoupled negative-sequence voltage is determined according to the branch negative-sequence current corresponding to each node, the negative-sequence reference voltage, and the admittance matrix corresponding to the negative sequence.

4. The three-phase unbalanced power flow line loss analysis method according to claim 1, characterized in that: Also includes: determining the active power of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component; A line loss rate is determined according to a ratio of the active power of the three-phase unbalanced system to the line loss.

5. The three-phase unbalanced power flow line loss analysis method according to claim 4, characterized in that: The positive-sequence electrical component includes an uncoupled positive-sequence current and an uncoupled positive-sequence voltage, and the negative-sequence electrical component includes an uncoupled negative-sequence current and an uncoupled negative-sequence voltage; The determining the active power of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component includes: Determining the active power of the balancing node according to the uncoupled positive-sequence current, the uncoupled positive-sequence voltage, the uncoupled negative-sequence current, and the uncoupled negative-sequence voltage corresponding to the balancing node in the three-phase unbalanced system; Determining the active power of the PV node according to the uncoupled positive-sequence current, uncoupled positive-sequence voltage, uncoupled negative-sequence current, and uncoupled negative-sequence voltage corresponding to the PV node in the three-phase unbalanced system; The active power of the three-phase unbalanced system is determined according to the active power of the balancing node and the active power of the PV node.

6. The three-phase unbalanced power flow line loss analysis method according to claim 5, characterized in that: Also includes: Converting the power flow model to determine a third relationship between the coupled zero-sequence current, the equivalent admittance, and the uncoupled zero-sequence current; Obtain the coupled positive sequence voltage, coupled negative sequence voltage and coupled zero sequence voltage corresponding to each node in the three-phase unbalanced system; determining the uncoupled zero-sequence current of each of the nodes according to the coupled positive-sequence voltage, the coupled negative-sequence voltage, the coupled zero-sequence voltage, and the third relationship; determining an uncoupled zero-sequence voltage at each of the nodes according to the uncoupled zero-sequence current and the third relationship; determining a positive-sequence power according to the uncoupled positive-sequence voltage and the uncoupled positive-sequence current; determining negative-sequence power according to the uncoupled negative-sequence voltage and the uncoupled negative-sequence current; determining zero-sequence power according to the coupled zero-sequence voltage and the coupled zero-sequence current; A line loss rate is determined according to the positive-sequence power, the negative-sequence power, the zero-sequence power, and the active power of the three-phase unbalanced system.

7. A three-phase unbalanced power flow line loss analysis system, characterized in that: include: A sequence component module is used to establish a power flow model of a three-phase unbalanced system based on a sequence component method; the power flow model includes admittance matrices corresponding to positive sequence, negative sequence, and zero sequence, respectively, and an equivalent admittance corresponding to any two of the positive sequence, the negative sequence, and the zero sequence; a power flow conversion module, configured to convert the power flow model to determine a first relationship between the coupled positive sequence current, the equivalent admittance, and the uncoupled positive sequence current, and a second relationship between the coupled negative sequence current, the equivalent admittance, and the uncoupled negative sequence current; a line loss analysis module, configured to determine a positive-sequence electrical component according to the first relationship, determine a negative-sequence electrical component according to the second relationship, and determine a line loss of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component; The positive-sequence electrical component includes the branch positive-sequence current, and the negative-sequence electrical component includes the branch negative-sequence current; Determining the line loss of the three-phase unbalanced system according to the positive-sequence electrical component and the negative-sequence electrical component includes: Determine a first ratio between the square of the branch positive sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the positive sequence of each node; Determine a second ratio between the square of the branch negative-sequence current of each node in the three-phase unbalanced system and the admittance matrix corresponding to the negative-sequence current of each node; A line loss of the three-phase unbalanced system is determined according to the sum of the first ratio and the second ratio.

8. An electronic device, characterized in that: The electronic device includes a memory and a processor, wherein a computer program is stored in the memory. When the computer program is executed by the processor, the processor performs the steps of the three-phase unbalanced power flow line loss analysis method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed, the steps of the three-phase unbalanced power flow line loss analysis method according to any one of claims 1 to 6 are implemented.

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