Equipment early warning method and system

Abstract

The invention discloses an equipment early warning method, which comprises the following steps of: obtaining a topological structure of a power distribution network, and constructing a topological directed graph according to the topological structure; performing load flow calculation according to the topological directed graph to obtain a load flow calculation result; determining an equipment operation state of the power distribution network based on the load flow calculation result, and performing equipment early warning according to the equipment operation state; by constructing the topology directed graph of the power distribution network, the equipment state of the power distribution network can be monitored and early warned in real time, and the operation efficiency and safety of the power distribution network are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution network, and in particular to an equipment early warning method and system. Background Art

[0002] In the field of smart distribution networks, the load conditions of various components in the power system can be monitored in real time through power flow calculation. Monitoring the operating status of equipment according to the load conditions and issuing equipment warnings are very important for the safe and stable operation of the power grid.

[0003] In the prior art, the power flow of the distribution network generally starts from the substation busbar outlet and ends at the distribution transformer. The voltage and power distribution of each node are solved through forward calculation and back iteration. However, in the data collection process of the distribution network, due to equipment failure, communication interruption and other reasons, measurement data may be missing. When the measurement data is missing, the traditional power flow calculation method is unavailable and the status of the distribution network is unknown, resulting in untimely equipment warnings in the distribution network and poor safety of the power system. Summary of the invention

[0004] The embodiment of the present invention provides an equipment early warning method based on power flow calculation, which can monitor and warn the equipment status of the distribution network in real time, thereby improving the operation efficiency and safety of the distribution network.

[0005] In a first aspect, an embodiment of the present invention provides a device early warning method, including:

[0006] Acquire a topological structure of a distribution network, and construct a topological directed graph according to the topological structure;

[0007] Performing power flow calculation according to the topological directed graph to obtain power flow calculation results;

[0008] The equipment operation status of the distribution network is determined based on the power flow calculation result, and equipment early warning is performed according to the equipment operation status.

[0009] Furthermore, the acquiring of the topological structure of the distribution network and constructing a topological directed graph according to the topological structure includes:

[0010] Acquire a topological structure of a distribution network, and construct a topological directed graph based on power flow direction according to the topological structure; wherein the nodes of the topological directed graph include distribution transformers and switch stations in the distribution network;

[0011] Assign weights to all edges in the topological directed graph.

[0012] Further, performing power flow calculation according to the topological directed graph to obtain power flow calculation results includes:

[0013] Based on the topological directed graph, voltage measurement data on the distribution transformer side in the distribution network is obtained, a set of measurement missing points is determined according to the voltage measurement data, and an upstream node of each measurement missing point in the set of measurement missing points is determined to obtain an upstream node set; wherein the upstream node is a switch station closest to the measurement missing point;

[0014] Determine a target upstream node according to the upstream node set, use the target upstream node as a head node for power flow calculation, and determine a terminal node for power flow calculation;

[0015] Based on the head-end node and the terminal node, a forward-backward substitution method is used to perform power flow calculation to obtain a power flow calculation result.

[0016] Further, determining the target upstream node according to the upstream node set includes:

[0017] For each upstream node in the upstream node set, calculating a weight sum of the upstream node and a corresponding measurement missing point to obtain a weight sum set;

[0018] A minimum weight sum is selected from the weight sum set, and an upstream node corresponding to the minimum weight sum is determined as a target upstream node.

[0019] Furthermore, the power flow calculation is performed based on the head-end node and the terminal node using a forward-backward method to obtain a power flow calculation result, including:

[0020] Calculating a voltage fill value of the head-end node and obtaining a head-end power of the head-end node;

[0021] Calculating power loss and voltage loss according to the power of the end node;

[0022] According to the voltage filling value, the head-end power, the power loss and the voltage loss, forward calculation is performed to obtain the power loss and the node voltage of each node;

[0023] According to the power loss and the node voltage obtained previously, the current and power distribution of each node are calculated.

[0024] Further, the calculating the voltage fill value of the head-end node includes:

[0025] Acquire all distribution transformers directly connected to the head-end node;

[0026] For each of the distribution transformers, calculating voltage correlations with other distribution transformers;

[0027] Obtaining a voltage reference value of the distribution transformer having the highest voltage correlation;

[0028] The voltage filling value of the head-end node is calculated according to the voltage reference value and the voltage loss coefficient.

[0029] Furthermore, the power flow calculation results include the power value of the distribution transformer, the power value of the distribution network line and the power value of the measurement missing point.

[0030] Further, the determining the equipment operation status of the distribution network based on the power flow calculation result includes:

[0031] Calculating a distribution transformer difference between the power value of the distribution transformer and the power maintenance value of the distribution transformer, and when the distribution transformer difference is greater than a preset distribution transformer abnormality threshold, determining that the distribution transformer is in a heavy load operation state;

[0032] Calculating a line difference between the power value of the distribution network line and the power maintenance value of the distribution network line, and when the line difference is greater than a preset distribution network line abnormality threshold, determining that the distribution network line is in an overload operation state;

[0033] When the power value of the measurement missing point is less than a preset power outage threshold, it is determined that there is a power outage in the measurement missing point area.

[0034] In a second aspect, an embodiment of the present invention provides a device early warning system, including:

[0035] A topological directed graph construction module is used to obtain the topological structure of the distribution network and construct a topological directed graph according to the topological structure;

[0036] A power flow calculation module, used to perform power flow calculation according to the topological directed graph to obtain a power flow calculation result;

[0037] The equipment early warning module is used to determine the equipment operation status of the distribution network based on the power flow calculation result, and to issue an equipment early warning according to the equipment operation status.

[0038] Furthermore, the topological directed graph construction module is also used for:

[0039] Acquire a topological structure of a distribution network, and construct a topological directed graph based on a power flow direction according to the topological structure; wherein the nodes of the topological directed graph include at least one of a distribution transformer, a switch station, a feeder, and a line in the distribution network;

[0040] Assign weights to all edges in the topological directed graph.

[0041] Compared with the prior art, an equipment early warning method provided by an embodiment of the present invention has the following beneficial effects: by acquiring the topological structure of the distribution network, a topological directed graph is constructed according to the topological structure; power flow calculation is performed according to the topological directed graph to obtain power flow calculation results; based on the power flow calculation results, the equipment operating status of the distribution network is determined, and equipment early warning is performed according to the equipment operating status; real-time monitoring and early warning of the distribution network status can be achieved, potential problems can be discovered and handled in a timely manner, the occurrence of equipment failures or power outages can be prevented, the operating efficiency and safety of the distribution network can be improved, and a strong guarantee can be provided for the sustainable development of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical features of the embodiments of the present invention, the drawings required for use in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 It is a flow chart of an embodiment of a device early warning method provided by the present invention;

[0044] Figure 2 It is a schematic diagram of the topological structure of a distribution network of an embodiment of a device early warning method provided by the present invention;

[0045] Figure 3 It is a topological directed graph of an embodiment of a device early warning method provided by the present invention;

[0046] Figure 4 It is a schematic diagram of a transformer equivalent model of an embodiment of an equipment early warning method provided by the present invention;

[0047] Figure 5 It is a schematic diagram of a line equivalent model of an embodiment of an equipment early warning method provided by the present invention;

[0048] Figure 6 It is a structural schematic diagram of an embodiment of an equipment early warning system provided by the present invention. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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 creative work are within the scope of protection of the present invention.

[0050] In a first aspect, an embodiment of the present invention provides a device early warning method, see Figure 1 , which is a flow chart of an embodiment of a device early warning method provided by the present invention.

[0051] like Figure 1 As shown, the method comprises the following steps:

[0052] S1: obtaining a topological structure of a distribution network, and constructing a topological directed graph according to the topological structure;

[0053] S2: Perform power flow calculation according to the topological directed graph to obtain power flow calculation results;

[0054] S3: Determine the equipment operation status of the distribution network based on the power flow calculation result, and issue an equipment warning according to the equipment operation status.

[0055] In a specific implementation, the topological structure of the distribution network is first obtained, and a topological directed graph is constructed according to the devices in the topological structure and the connection relationship between the devices. The topological directed graph is used to perform power flow calculations, and the voltage of each node and the current, power and other parameters of each branch are calculated to obtain power flow calculation results. The power flow calculation results are analyzed to check whether there are any abnormalities in the operating status of the equipment in the distribution network. For equipment that is assessed to be abnormal, an early warning mechanism is triggered, and the early warning may include sending alarm information to operation and maintenance personnel, automatically adjusting control strategies, etc.

[0056] In summary, the present invention obtains the topological structure of the distribution network, constructs a topological directed graph according to the topological structure; performs power flow calculation according to the topological directed graph to obtain power flow calculation results; determines the equipment operating status of the distribution network based on the power flow calculation results, and performs equipment early warning according to the equipment operating status. This can achieve real-time monitoring and early warning of the distribution network status, timely discover and deal with potential problems, prevent equipment failures or power outages, improve the operating efficiency and safety of the distribution network, and provide a strong guarantee for the sustainable development of the power system.

[0057] In an optional implementation, the acquiring the topological structure of the distribution network and constructing a topological directed graph according to the topological structure includes:

[0058] Acquire a topological structure of a distribution network, and construct a topological directed graph based on power flow direction according to the topological structure; wherein the nodes of the topological directed graph include distribution transformers and switch stations in the distribution network;

[0059] Assign weights to all edges in the topological directed graph.

[0060] Specifically, the topology of the distribution network is obtained. For example, see Figure 2As shown, it is a schematic diagram of the topological structure of the distribution network of a device early warning method provided by the present invention. In the medium-voltage distribution network, the head end of the topological structure is generally a 10kV distribution feeder and the end is a distribution transformer. The middle is connected by a switch station, a ring network cabinet and each branch line. A topological directed graph based on the flow direction is constructed according to the topological structure; wherein the nodes of the topological directed graph are the distribution transformers and switch stations in the distribution network, and the edges of the topological directed graph are the connection relationships between the various devices in the distribution network. The direction of the edge, that is, the direction of power flow, is determined based on the power flow direction. For example, the edge from the switch station to the distribution transformer indicates that power flows from the switch station to the distribution transformer. For example, see Figure 3 , Figure 3 A schematic diagram of a topological directed graph of a device early warning method provided by the present invention.

[0061] Assign weights to all edges between nodes in the constructed topological directed graph. For example, the weight of each edge can be assigned to 1, and the sum of the weights of any two node edges represents the distance between the two nodes.

[0062] Through the above steps, a distribution network topology directed graph based on the flow direction can be constructed, and appropriate weights can be assigned to each edge in the topology directed graph. This can not only intuitively display the structure of the distribution network and the flow of power, but also provide strong support for subsequent power system analysis and optimization.

[0063] In an optional implementation, performing power flow calculation according to the topological directed graph to obtain a power flow calculation result includes:

[0064] Based on the topological directed graph, voltage measurement data on the distribution transformer side in the distribution network is obtained, a set of measurement missing points is determined according to the voltage measurement data, and an upstream node of each measurement missing point in the set of measurement missing points is determined to obtain an upstream node set; wherein the upstream node is a switch station closest to the measurement missing point;

[0065] Determine a target upstream node according to the upstream node set, use the target upstream node as a head node for power flow calculation, and determine a terminal node for power flow calculation;

[0066] Based on the head-end node and the terminal node, a forward-backward substitution method is used to perform power flow calculation to obtain a power flow calculation result.

[0067] Specifically, in the data collection process of the distribution network, due to equipment failure, communication interruption and other reasons, measurement data may be missing. The voltage measurement data on the distribution transformer side in the topological directed graph is obtained. These data can be obtained from the smart meter. The voltage measurement data is filtered for null values ​​to determine which distribution transformer nodes have missing voltage measurement data, thereby obtaining a set of measurement missing points. In the topological structure of the distribution network, switch stations are usually used as key nodes for controlling and distributing electric energy. They are connected to multiple downstream nodes, such as transformers and feeders. Through the topological directed graph, the switch station closest to each measurement missing point can be found, that is, the upstream node of each distribution transformer. The intersection of all upstream nodes is calculated to obtain the upstream node set. The specific formula is as follows:

[0068]

[0069] Among them, S represents the set of measurement missing points, T i represents the i-th distribution transformer, n is the number of distribution transformers in the topological directed graph, P i Indicates distribution transformer T i The upstream node of , D represents the upstream node set.

[0070] Since the upstream nodes are defined according to the directed graph, there must be elements in the intersection of the upstream nodes of the measurement missing points. In the upstream node set D, it is necessary to select a target upstream node as the head node of the power flow calculation, and use the distribution transformer and the head end of the feeder with measurement as the end node of the power flow calculation. Based on the head node and the end node, the forward and backward method is used to perform the power flow calculation to obtain the power flow calculation result.

[0071] Through the above steps, based on the topological directed graph of the distribution network and the voltage measurement data, the measurement missing problem can be effectively handled and accurate power flow calculation can be performed, which is helpful to evaluate the operating status of the distribution network and provide strong support for subsequent equipment early warning, troubleshooting, etc.

[0072] In an optional implementation, determining the target upstream node according to the upstream node set includes:

[0073] For each upstream node in the upstream node set, calculating a weight sum of the upstream node and a corresponding measurement missing point to obtain a weight sum set;

[0074] A minimum weight sum is selected from the weight sum set, and an upstream node corresponding to the minimum weight sum is determined as a target upstream node.

[0075] Specifically, according to the weights of each edge in the topological directed graph, for each upstream node in the upstream node set, the sum of the weights between it and the corresponding measurement missing point is calculated. The sum of the weights reflects the distance between the upstream node and the measurement missing point, and the weight sum set of all upstream nodes is obtained. The minimum weight sum is selected from the weight sum set. The upstream node corresponding to the minimum weight sum is the target upstream node.

[0076] In an optional implementation, the step of performing power flow calculation based on the head-end node and the terminal node by adopting a forward-backward method to obtain a power flow calculation result includes:

[0077] Calculating a voltage fill value of the head-end node and obtaining a head-end power of the head-end node;

[0078] Calculating power loss and voltage loss according to the power of the end node;

[0079] According to the voltage filling value, the head-end power, the power loss and the voltage loss, forward-calculate the power loss and the node voltage of each node;

[0080] According to the power loss and the node voltage obtained previously, the current and power distribution of each node are calculated.

[0081] Specifically, when calculating the power flow of the distribution network, it is first necessary to convert the transformer and the line into equivalent circuits, convert the transformer into a τ-type equivalent circuit, and convert the line into a π-type equivalent circuit. Based on these equivalent circuits, the power flow calculation of the distribution network is performed. For example, see Figure 4 and Figure 5 , Figure 4 A schematic diagram of a transformer equivalent model of an equipment early warning method provided by the present invention, Figure 4 k is the transformer ratio, Z pb is the transformer impedance and has been converted to the high voltage side, ΔP0+jΔQ0 is the no-load loss and short-circuit loss of the distribution transformer, Pload+jQload is the distribution transformer load, Figure 5 A schematic diagram of a line equivalent model of an equipment early warning method provided by the present invention, Figure 5 Zline is the line impedance and Yline is the line admittance.

[0082] Since there is no measurement data at the head-end node, it is necessary to fill in the voltage value of the head-end node based on other information, and obtain the head-end power of the head-end node. The measured distribution transformer and feeder head end are used as the end node, and the power flow is calculated by forward and backward substitution, that is, the power loss and voltage loss are calculated according to the power of the end node, and the head-end voltage is forwarded based on the power flow calculation principle, and the power loss and voltage loss are calculated by back substitution according to the head-end voltage and the head-end power, so as to calculate the power loss and node voltage of each node. The voltage drop and impedance can be obtained when the distribution network parameters and the node voltage are known, so as to calculate the current of each node. Since the distribution transformer voltage is known, the distribution transformer power can be calculated to realize flexible power flow calculation. The specific formulas for the above content are as follows:

[0083]

[0084] in, represents the power loss of the impedance branch, S′2 represents the apparent power at the end, P2′ represents the active power at the end, Q′2 represents the reactive power at the end, R represents the branch resistance, X represents the branch reactance, U2 represents the terminal voltage, ΔP z Represents the active power loss of the impedance branch, ΔQ z represents the reactive power loss of the impedance branch, represents the power loss of the admittance branch, Y represents the branch admittance, G represents the branch conductance, B represents the branch susceptance, U1 represents the head end voltage, ΔP Y1 Represents the active power loss of the admittance branch, ΔQ Y1 Represents the reactive loss of the admittance branch, ΔU2 represents the longitudinal component of the voltage drop, and δU2 represents the transverse component of the voltage drop.

[0085] The calculation formula for the power flow of the missing measurement part is as follows:

[0086]

[0087] Among them, I represents the branch current, U1 represents the head-end voltage, U2 represents the terminal voltage, R+jX represents the branch equivalent impedance, and P+jQ represents the terminal power.

[0088] In an optional implementation manner, the calculating the voltage fill value of the head-end node includes:

[0089] Acquire all distribution transformers directly connected to the head-end node;

[0090] For each of the distribution transformers, calculating voltage correlations with other distribution transformers;

[0091] Obtaining a voltage reference value of the distribution transformer having the highest voltage correlation;

[0092] The voltage filling value of the head-end node is calculated according to the voltage reference value and the voltage loss coefficient.

[0093] Specifically, since there is no voltage measurement data at the head-end node, voltage data is filled in. For each distribution transformer directly connected to the head-end node, the voltage correlation between its voltage measurement value and the voltage measurement values ​​of other distribution transformers is calculated. The correlation can be calculated by a variety of statistical methods. The voltage measurement value of the distribution transformer with the highest voltage correlation is selected as the voltage reference value. The voltage reference value is added to the estimated voltage drop value, and the result is used as the voltage filling value of the head-end node. The specific formula is as follows:

[0094]

[0095] Where x, y represent the voltage measurement values ​​of different distribution transformers, n represents the number of elements of voltage measurement data, r xy represents the Pearson correlation coefficient between distribution transformer x and distribution transformer y, U trans represents the voltage reference value, K represents the voltage loss coefficient, U sta Indicates the voltage fill value.

[0096] In an optional implementation, the power flow calculation result includes a power value of a distribution transformer, a power value of a distribution network line, and a power value of a measurement missing point.

[0097] In an optional implementation, determining the equipment operating status of the distribution network based on the power flow calculation result includes:

[0098] Calculating a distribution transformer difference between the power value of the distribution transformer and the power maintenance value of the distribution transformer, and when the distribution transformer difference is greater than a preset distribution transformer abnormality threshold, determining that the distribution transformer is in a heavy load operation state;

[0099] Calculating a line difference between the power value of the distribution network line and the power maintenance value of the distribution network line, and when the line difference is greater than a preset distribution network line abnormality threshold, determining that the distribution network line is in an overload operation state;

[0100] When the power value of the measurement missing point is less than a preset power outage threshold, it is determined that there is a power outage in the measurement missing point area.

[0101] Specifically, the power flow calculation results include the power value of the distribution transformer, the power value of the distribution network line and the power value of the measurement missing point. The equipment operation status of the distribution network is judged according to the power flow calculation results, the distribution transformer abnormality threshold, the distribution network line abnormality threshold and the power outage threshold are pre-set, and the difference between the distribution transformer power value and the distribution transformer power maintenance value is calculated, which is recorded as the distribution transformer difference. When the distribution transformer difference is greater than the distribution transformer abnormality threshold, it is determined that the distribution transformer is in a heavy load operation state. The difference between the distribution network line power value and the distribution network line power maintenance value is calculated, which is recorded as the line difference. When the line difference is greater than the distribution network line abnormality threshold, it is determined that the distribution network line is in a heavy load operation state. When the power value of the measurement missing point is less than the preset power outage threshold, it is determined that there is a power outage in the measurement missing point area.

[0102] In a second aspect, an embodiment of the present invention provides a device early warning system, see Figure 6 , which is a structural diagram of an embodiment of an equipment early warning system provided by the present invention.

[0103] like Figure 6 As shown, the system comprises:

[0104] A topological directed graph construction module 21 is used to obtain a topological structure of the distribution network and construct a topological directed graph according to the topological structure;

[0105] A power flow calculation module 22, used to perform power flow calculation according to the topological directed graph to obtain a power flow calculation result;

[0106] The equipment early warning module 23 is used to determine the equipment operation status of the distribution network based on the power flow calculation result, and to issue an equipment early warning according to the equipment operation status.

[0107] In an optional implementation, the topology directed graph construction module 21 is further used for:

[0108] Acquire a topological structure of a distribution network, and construct a topological directed graph based on a power flow direction according to the topological structure; wherein the nodes of the topological directed graph include at least one of a distribution transformer, a switch station, a feeder, and a line in the distribution network;

[0109] Assign weights to all edges in the topological directed graph.

[0110] In an optional implementation, the power flow calculation module 22 is further used to obtain voltage measurement data on the distribution transformer side in the distribution network based on the topological directed graph, determine a measurement missing point set according to the voltage measurement data, and determine an upstream node of each measurement missing point in the measurement missing point set to obtain an upstream node set; wherein the upstream node is a switch station closest to the measurement missing point;

[0111] Determine a target upstream node according to the upstream node set, use the target upstream node as a head node for power flow calculation, and determine a terminal node for power flow calculation;

[0112] Based on the head-end node and the terminal node, a forward-backward substitution method is used to perform power flow calculation to obtain a power flow calculation result.

[0113] In an optional implementation, the power flow calculation module 22 is further used for:

[0114] For each upstream node in the upstream node set, calculating a weight sum of the upstream node and a corresponding measurement missing point to obtain a weight sum set;

[0115] A minimum weight sum is selected from the weight sum set, and an upstream node corresponding to the minimum weight sum is determined as a target upstream node.

[0116] In an optional implementation, the power flow calculation module 22 is further used for:

[0117] Calculating a voltage fill value of the head-end node and obtaining a head-end power of the head-end node;

[0118] Calculating power loss and voltage loss according to the power of the end node;

[0119] According to the voltage filling value, the head-end power, the power loss and the voltage loss, forward calculation is performed to obtain the power loss and the node voltage of each node;

[0120] According to the power loss and the node voltage obtained previously, the current and power distribution of each node are calculated.

[0121] In an optional implementation, the power flow calculation module 22 is further used for:

[0122] Acquire all distribution transformers directly connected to the head-end node;

[0123] For each of the distribution transformers, calculating voltage correlations with other distribution transformers;

[0124] Obtaining a voltage reference value of the distribution transformer having the highest voltage correlation;

[0125] The voltage filling value of the head-end node is calculated according to the voltage reference value and the voltage loss coefficient.

[0126] In an optional implementation, the power flow calculation result includes a power value of a distribution transformer, a power value of a distribution network line, and a power value of a measurement missing point.

[0127] In an optional implementation, the equipment early warning module 23 is further used for:

[0128] Calculating a distribution transformer difference between the power value of the distribution transformer and the power maintenance value of the distribution transformer, and when the distribution transformer difference is greater than a preset distribution transformer abnormality threshold, determining that the distribution transformer is in a heavy load operation state;

[0129] Calculating a line difference between the power value of the distribution network line and the power maintenance value of the distribution network line, and when the line difference is greater than a preset distribution network line abnormality threshold, determining that the distribution network line is in an overload operation state;

[0130] When the power value of the measurement missing point is less than a preset power outage threshold, it is determined that there is a power outage in the measurement missing point area.

[0131] The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. It should be pointed out that for those skilled in the art, several equivalent obvious variations and / or equivalent substitutions can be made without departing from the technical principles of the present invention. These obvious variations and / or equivalent substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A device early warning method, characterized in that: include: Acquire a topological structure of a distribution network, and construct a topological directed graph according to the topological structure; Performing power flow calculation according to the topological directed graph to obtain power flow calculation results; The equipment operation status of the distribution network is determined based on the power flow calculation result, and equipment early warning is performed according to the equipment operation status.

2. The equipment early warning method according to claim 1, characterized in that: The obtaining of the topological structure of the distribution network and constructing a topological directed graph according to the topological structure includes: Acquire a topological structure of a distribution network, and construct a topological directed graph based on power flow direction according to the topological structure; wherein the nodes of the topological directed graph include distribution transformers and switch stations in the distribution network; Assign weights to all edges in the topological directed graph.

3. The equipment early warning method according to claim 1, characterized in that: The performing power flow calculation according to the topological directed graph to obtain the power flow calculation result includes: Based on the topological directed graph, voltage measurement data on the distribution transformer side in the distribution network is obtained, a set of measurement missing points is determined according to the voltage measurement data, and an upstream node of each measurement missing point in the set of measurement missing points is determined to obtain an upstream node set; wherein the upstream node is a switch station closest to the measurement missing point; Determine a target upstream node according to the upstream node set, use the target upstream node as a head node for power flow calculation, and determine a terminal node for power flow calculation; Based on the head-end node and the terminal node, a forward-backward substitution method is used to perform power flow calculation to obtain a power flow calculation result.

4. The equipment early warning method according to claim 3, characterized in that: The determining the target upstream node according to the upstream node set includes: For each upstream node in the upstream node set, calculating a weight sum of the upstream node and a corresponding measurement missing point to obtain a weight sum set; A minimum weight sum is selected from the weight sum set, and an upstream node corresponding to the minimum weight sum is determined as a target upstream node.

5. The equipment early warning method according to claim 3, characterized in that: The method of performing power flow calculation based on the head-end node and the terminal node by using a forward-backward method to obtain a power flow calculation result includes: Calculating a voltage fill value of the head-end node and obtaining a head-end power of the head-end node; Calculating power loss and voltage loss according to the power of the end node; According to the voltage filling value, the head-end power, the power loss and the voltage loss, forward calculation is performed to obtain the power loss and the node voltage of each node; According to the power loss and the node voltage obtained previously, the current and power distribution of each node are calculated.

6. The equipment early warning method according to claim 5, characterized in that: The calculating the voltage fill value of the head-end node includes: Acquire all distribution transformers directly connected to the head-end node; For each of the distribution transformers, calculating voltage correlations with other distribution transformers; Obtaining a voltage reference value of the distribution transformer having the highest voltage correlation; The voltage filling value of the head-end node is calculated according to the voltage reference value and the voltage loss coefficient.

7. The equipment early warning method according to claim 1, characterized in that: The power flow calculation results include the power value of the distribution transformer, the power value of the distribution network line and the power value of the measurement missing point.

8. The equipment early warning method according to claim 7, characterized in that: The determining the equipment operation status of the distribution network based on the power flow calculation result includes: Calculating the distribution transformer difference between the power value of the distribution transformer and the power maintenance value of the distribution transformer, and when the distribution transformer difference is greater than a preset distribution transformer abnormality threshold, determining that the distribution transformer is in a heavy load operation state; Calculating a line difference between the power value of the distribution network line and the power maintenance value of the distribution network line, and when the line difference is greater than a preset distribution network line abnormality threshold, determining that the distribution network line is in an overload operation state; When the power value of the measurement missing point is less than a preset power outage threshold, it is determined that there is a power outage in the measurement missing point area.

9. An equipment early warning system, characterized in that: include: A topological directed graph construction module is used to obtain the topological structure of the distribution network and construct a topological directed graph according to the topological structure; A power flow calculation module, used to perform power flow calculation according to the topological directed graph to obtain a power flow calculation result; The equipment early warning module is used to determine the equipment operation status of the distribution network based on the power flow calculation result, and to issue an equipment early warning according to the equipment operation status.

10. The equipment early warning system according to claim 9, characterized in that: The topology directed graph building module is also used for: Acquire a topological structure of a distribution network, and construct a topological directed graph based on a power flow direction according to the topological structure; wherein the nodes of the topological directed graph include at least one of a distribution transformer, a switch station, a feeder, and a line in the distribution network; Assign weights to all edges in the topological directed graph.

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