Power distribution network load removal method and device, computer equipment and readable storage medium

Abstract

The invention relates to a power distribution network load removal method and device, computer equipment and a readable storage medium. The method comprises the following steps: under the condition that a power distribution network is abnormal, performing weighted calculation on index values of load nodes under a plurality of evaluation indexes to obtain weighted comprehensive scores of the load nodes, performing mean calculation on the weighted comprehensive scores of the load nodes in a device unit to obtain an average load comprehensive score of the device unit, and calculating the average load comprehensive score of the device unit according to the average load comprehensive score; layering the load nodes according to the weighted comprehensive scores of the load nodes in the power distribution network to obtain a plurality of load layers, and layering the device units according to the average load comprehensive scores of the device units in the power distribution network to obtain a plurality of device layers; generating a priority constraint condition based on the hierarchy of the load layer and the hierarchy of the device layer, and determining a load removal scheme of the power distribution network based on the priority constraint condition; and sending a load cut-off instruction to the protection and measurement device based on the load cut-off scheme. By adopting the method, the accuracy of load removal can be improved.

Description

Technical Field

[0001] This application relates to the field of power system safety and stability control technology, and in particular to a method, apparatus, computer equipment and readable storage medium for load shedding in a distribution network. Background Technology

[0002] With the large-scale integration of distributed generation, the distribution network is gradually transforming from a traditional unidirectional radial network into a complex network with multiple power sources and various configurations. While this transformation improves energy efficiency, it also brings new security challenges: the output fluctuations of distributed generation, the dynamic characteristics of loads, and the potential islanding state during grid faults significantly affect the frequency and voltage stability of the distribution network. Under-frequency load shedding (UFLS) and under-voltage load shedding (UVLS) are the most commonly used methods to address the frequency and voltage stability issues of the distribution network, respectively.

[0003] Currently, research on low-voltage load shedding and low-frequency load shedding generally focuses on single conditions such as low voltage or low frequency. However, in actual power grid operation, voltage and frequency are two electrical state variables that are coupled and influence each other. The single nature of the control variables makes them lack coordination. Using only a single control strategy cannot effectively achieve optimized control of low-frequency and low-voltage phenomena in the power grid.

[0004] Active distribution networks are characterized by the strong randomness of distributed power output and the difficulty of source-load coordination among multiple nodes. Existing low-frequency and low-voltage load shedding methods have drawbacks such as low overall coordination and inability to accurately disconnect load lines. Therefore, it is urgent to design a practical new low-frequency and low-voltage load shedding method (i.e., load shedding method) tailored to the operating characteristics of active distribution networks to improve the accuracy of load shedding. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, computer device, computer-readable storage medium, and computer program product that can improve the accuracy of load removal in order to address the above-mentioned technical problems.

[0006] On one hand, this application provides a method for load shedding in a distribution network, comprising: in the event of an anomaly in the distribution network, for each load node in the distribution network, weighted calculation of the index values ​​of the load node under multiple evaluation indicators to obtain a weighted comprehensive score of the load node; for each device unit in the distribution network, averaging the weighted comprehensive scores of the load nodes in the device unit to obtain an average comprehensive load score of the device unit, wherein the device unit is obtained by dividing the protection and monitoring devices in the distribution network according to regions, and the load node in the device unit refers to the load node corresponding to the protection and monitoring device included in the device unit. The load nodes are stratified according to their weighted comprehensive scores in the distribution network to obtain multiple load layers of different levels. Similarly, the device units are stratified according to their average comprehensive load scores in the distribution network to obtain multiple device layers of different levels. Priority constraints are generated based on the load layer and device layer levels, and a load shedding scheme for the distribution network is determined based on these priority constraints. The priority constraints are used to limit the shedding priority of load nodes. The load shedding scheme is verified, and if the verification passes, a load shedding command is sent to the protection device based on the load shedding scheme.

[0007] On the other hand, this application also provides a distribution network load shedding device, comprising: a first score determination module, used to, in the event of an anomaly in the distribution network, perform weighted calculations on the index values ​​of each load node under multiple evaluation indicators to obtain a weighted comprehensive score for the load node; a second score determination module, used to, for each device unit in the distribution network, calculate the average of the weighted comprehensive scores of the load nodes in the device unit to obtain an average comprehensive load score for the device unit, wherein the device unit is obtained by dividing the protection and monitoring devices in the distribution network according to regions, and the load node in the device unit refers to the load node corresponding to the protection and monitoring device included in the device unit; layer The load partitioning module is used to partition load nodes into multiple load layers based on their weighted comprehensive scores, and to partition device units into multiple device layers based on their average comprehensive load scores. The load shedding scheme determination module is used to generate priority constraints based on the load layer and device layer levels, and to determine the load shedding scheme for the distribution network based on these priority constraints. These priority constraints limit the shedding priority of load nodes. The scheme execution module verifies the load shedding scheme, and if the verification passes, sends a load shedding command to the load protection device based on the load shedding scheme.

[0008] On the other hand, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described distribution network load shedding method.

[0009] On the other hand, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the above-described distribution network load shedding method.

[0010] On the other hand, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps in the above-described distribution network load shedding method.

[0011] The aforementioned distribution network load shedding method, device, computer equipment, computer-readable storage medium, and computer program product, in the event of a distribution network anomaly, perform weighted calculations on the index values ​​of each load node under multiple evaluation indicators to obtain a weighted comprehensive score for the load node; for each device unit in the distribution network, the average of the weighted comprehensive scores of the load nodes in the device unit is calculated to obtain the average comprehensive load score of the device unit. The device unit is obtained by dividing the protection and monitoring devices in the distribution network according to regions, and the load node in the device unit refers to the load node corresponding to the protection and monitoring device included in the device unit; the load nodes are layered according to the weighted comprehensive scores of the load nodes in the distribution network to obtain multiple load layers of different levels, and the device units are layered according to the average comprehensive load score of the device units in the distribution network to obtain multiple device layers of different levels; priority constraints are generated based on the load layer level and the device layer level, and the load shedding scheme of the distribution network is determined based on the priority constraints, which are used to limit the shedding priority of load nodes; the load shedding scheme is verified, and if the verification passes, a load shedding command is sent to the protection and monitoring device based on the load shedding scheme. A novel and practical low-frequency low-voltage load shedding method (i.e., load shedding method) has been implemented, which improves the accuracy of load shedding. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a diagram illustrating the application environment of a power distribution network load shedding method in one embodiment.

[0014] Figure 2 This is a flowchart illustrating a distribution network load shedding method in one embodiment;

[0015] Figure 3 This is a flowchart illustrating a distribution network load shedding method in another embodiment;

[0016] Figure 4 Here is a diagram of an IEEE 39-node system in one embodiment;

[0017] Figure 5 This is a flowchart illustrating the CDCL algorithm in one embodiment;

[0018] Figure 6 This is a structural block diagram of a power distribution network load shedding device in one embodiment;

[0019] Figure 7 This is an internal structural diagram of a computer device in one embodiment;

[0020] Figure 8 This is a diagram of the internal structure of a computer device in another embodiment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] The distribution network load shedding method provided in this application embodiment can be applied to, for example, Figure 1 In the application environment shown, the environment includes a power distribution network 102 and a computer device 104. The power distribution network 102 can be an active or passive power distribution network. The computer device 104 can be a terminal or a server, or a centralized control station for the power distribution network. The power distribution network 102 includes multiple load nodes and multiple monitoring and protection devices, with each monitoring and protection device corresponding to at least one load node. The monitoring and protection device is used to monitor or control the corresponding load node. The monitoring and protection device refers to an integrated monitoring and protection device. The power distribution network 102 and the computer device 104 can be directly or indirectly connected via wired or wireless communication, which is not limited herein.

[0023] Specifically, the load protection device can collect electrical quantity information of the load at fixed time intervals (e.g., 0.1 seconds) and record the electrical quantity information collected within the most recent time period T. For example, if T=5 seconds, the electrical quantity information collected within the most recent 5 seconds will be stored. T can be set according to actual needs; for example, T can be twice the communication time between the load protection device and the computer equipment. The communication time refers to the maximum delay required for the load protection device to transmit data from the local location to the computer equipment. The load protection devices installed at each load of the distribution line monitor the operating status of each load in real time. When an abnormality is detected, the device promptly reports the abnormality to the centralized control station and sends the load electrical quantity information, trip output pressure plate status, and the time of the abnormality. The computer equipment 104 can determine the load shedding plan based on the data reported by the load protection device and instruct the load protection device to execute the load shedding plan.

[0024] The terminal can be, but is not limited to, desktop computers, laptops, smartphones, and tablets. The server can be a standalone physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server providing cloud computing services. Cloud servers are used to provide basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communication, middleware services, domain name services, security services, CDN (Content Delivery Network), and big data and artificial intelligence platforms.

[0025] In one exemplary embodiment, such as Figure 2 As shown, a method for load shedding in a distribution network is provided. This method can be executed by a terminal or a server, or by both a terminal and a server. This method can be applied to... Figure 1 The following steps are described for 104 examples of computer devices:

[0026] Step 202: In the event of an anomaly in the distribution network, for each load node in the distribution network, the index values ​​of the load node under multiple evaluation indicators are weighted and calculated to obtain the weighted comprehensive score of the load node.

[0027] Specifically, when the monitoring device detects an abnormal condition, such as the trip output pressure plate changing to an off state or a node frequency change reaching 5% and lasting for 0.3 seconds, it reports the abnormal condition and the load information at the time of the abnormal condition to the computer equipment. The load information includes: the time of the abnormality t1, and the active power of load node i at the time of the abnormality t1. The reactive power of load node i at the abnormal time t1 The report includes the status of the trip output pressure plate (engaged or deactivated) at the abnormal time t1, the active and reactive power of load node i under normal conditions as recorded last time before the abnormal situation, and the voltage amplitude of load node i under normal conditions as recorded last time before the abnormal situation. The value of i ranges from 1 to n, where n is the number of load nodes in the distribution network. The specific reporting content is shown in Table 1.

[0028] Table 1

[0029]

[0030] In some embodiments, for load node i, the computer device can calculate the active power of load node i at time t1. The active power of load node i last recorded before the anomaly The difference between them is taken as the active power deficit of the load, and the sum of the active power deficits of each load is calculated to obtain the total active power deficit. For example, This represents the active power deficit at load node i. This represents the total active power deficit. , .

[0031] In some embodiments, for load node i, the computer device can measure the reactive power of load node i at time t1. The reactive power of load node i last recorded before the anomaly The difference between them is taken as the reactive power deficit of the load, for example, The reactive power deficit representing load node i is then... .

[0032] In some embodiments, multiple evaluation indicators include, but are not limited to, at least one of electrical distance, interruption loss, electricity consumption sector, or recovery time. Electrical distance refers to the electrical distance between the load node and the abnormal load node, and the unit can be km (kilometers). Interruption loss refers to the monetary loss per unit time after a load node is interrupted, and the unit can be RMB 10,000 / hour. Electricity consumption sector refers to the type of sector to which the load node belongs. Sector types can be, but are not limited to, military, hospital, government, industry, commerce, and ordinary residents. Different sector types may have the same or different indicator values; for example, the indicator value is 5 for military and hospital sectors; 4 for government sectors; 3 for industry sectors; 2 for commerce sectors; and 1 for ordinary residents sectors. Recovery time refers to the time it takes for the load node to return to normal operation after a fault, and the unit can be hours. The indicator values ​​are provided by the monitoring and protection device.

[0033] In some embodiments, before weighting the index values, the index values ​​can be normalized to obtain normalized index values, thereby unifying indices with different dimensions into the range of 0 to 1 and eliminating dimensional differences. Then, the normalized index values ​​are weighted and calculated. For example, for the j-th evaluation index, the index value of the i-th load node is represented as... The normalized index value of the i-th load node is expressed as: ,but The calculation formula is as follows:

[0034] .

[0035] in, This represents the largest value among the index values ​​of each load node under the j-th evaluation index. This represents the minimum value among the index values ​​for each load node under the j-th evaluation index. For example, if the index value for the electrical distance of the i-th load node is 10km, and the maximum value among the index values ​​for the electrical distance of each load node is 30km and the minimum value is 6km, then the normalized index value for the electrical distance of the i-th load node is 0.167.

[0036] use The weighted composite score representing load node i (i.e., the i-th load node) is expressed as... The weight of the j-th evaluation indicator is represented by... This represents the normalized index value of the i-th load node under the j-th evaluation index. Then... Where m represents the number of evaluation indicators, and j ranges from 1 to m. The weights of the evaluation indicators can be set according to actual needs. For example, the weights of each evaluation indicator are shown in Table 2:

[0037] Table 2

[0038]

[0039] Step 204: For each device unit in the distribution network, the weighted comprehensive score of the load nodes in the device unit is averaged to obtain the average load comprehensive score of the device unit. The device unit is obtained by dividing the protection and monitoring devices in the distribution network according to the region. The load node in the device unit refers to the load node corresponding to the protection and monitoring device contained in the device unit.

[0040] Each device unit includes a monitoring device for a specific area or region. That is, a device unit may contain at least one monitoring device.

[0041] Specifically, the computer equipment divides all integrated protection and monitoring devices in the distribution network into M integrated protection and monitoring device units (hereinafter referred to as device units) according to the area, and sets a priority for each device unit. The priority setting should take into account the average load comprehensive score of the device unit. The formula for calculating the average load comprehensive score of the m-th device unit is as follows:

[0042] ;

[0043] in, The average load comprehensive score for the m-th device unit. This represents the number of load nodes contained in the m-th device unit, i.e. There are M device units connected to n load nodes, where 1 ≤ m ≤ M. For the m-th device unit, the first... The weighted composite score of each load node. .

[0044] Step 206: Based on the weighted comprehensive score of the load nodes in the distribution network, the load nodes are divided into multiple load layers of different levels. Based on the average comprehensive load score of the device units in the distribution network, the device units are divided into multiple device layers of different levels.

[0045] In some embodiments, load nodes are stratified according to their weighted composite scores in the distribution network to obtain multiple load layers of different levels, and device units are stratified according to their average composite load scores in the distribution network to obtain multiple device layers of different levels. This includes: stratification based on the equal-width partitioning method and the maximum and minimum values ​​of the weighted composite scores of each load node to obtain multiple load layers of different levels; and stratification based on the equal-width partitioning method and the maximum and minimum values ​​of the average composite load scores of each device unit to obtain multiple device layers of different levels. In this embodiment, the equal-width partitioning method can quickly complete the stratification.

[0046] In some embodiments, the computer equipment can use the equal-width partitioning method to divide the device units into four device layers according to the average load comprehensive score from low to high, with each device layer corresponding to a level. Similarly, the equal-width partitioning method can be used to divide all load nodes in the distribution network into three load layers according to the weighted comprehensive score from low to high, with each load layer corresponding to a level. The formula for calculating the width of each level in the equal-width partitioning method is as follows:

[0047] ;

[0048] Where N represents the number of levels. In the scenario of layering load nodes, N represents the number of load layers. In the scenario of layering device units, N represents the number of device layers. max represents the maximum value and min represents the minimum value. In the scenario of layering load nodes, max represents the maximum weighted comprehensive score and min represents the minimum weighted comprehensive score. In the scenario of layering device units, max represents the maximum average load comprehensive score and min represents the minimum average load comprehensive score.

[0049] Step 208: Generate priority constraints based on the load layer hierarchy and device layer hierarchy, and determine the load shedding scheme of the distribution network based on the priority constraints. The priority constraints are used to limit the shedding priority of load nodes.

[0050] The load layer contains at least one load node, and the load layer level of a load node is the level of the load layer to which that load node belongs. The device layer may contain at least one device unit, and the device layer level of the load node corresponding to the protection and monitoring device within that device unit is the level of the device layer to which the protection and monitoring device belongs. For example, if load node i belongs to the first load layer, then the load layer level of load node i is 1. If the protection and monitoring device corresponding to load node i belongs to the first device layer, then the device layer level of load node i is 1.

[0051] In the event of an anomaly, the load nodes to be disconnected are determined according to the priority order of load layer first, followed by device layer. This can be achieved by using a two-dimensional list with priority based on load layer first, then device layer. Taking a 3-layer load layer and a 4-layer device layer as an example, the priority order is shown in Table 3. Numbers 1 to 12 (the starting number of the cell) represent priorities, with smaller numbers indicating higher priorities. For load nodes that are identical at both the load and device layers, the priority order is to preferentially disconnect load nodes with lower active power.

[0052] Table 3

[0053]

[0054] In some embodiments, a Boolean variable is defined for each load node in each device layer. If the distribution network system has m device units, these m device units are divided into 4 layers based on their average load composite score, and the m device units have n load nodes, these n load nodes are divided into 3 layers based on their weighted composite score. Let load node i be located in the h-th load layer (h=1, 2, 3) and in the k-th device layer (k=1, 2, 3, 4), then the Boolean variable corresponding to load node i is: ,but The value of ∈ {0, 1}. For Boolean variables, the following definition applies: if the Boolean variable for load node i is assigned a value of 1, it indicates that load node i needs to undergo partial shedding during the optimization decision-making process, and the shedding amount is defined as 30% of the active power of load node i under rated conditions; if the Boolean variable for load node i is assigned a value of 0, it indicates that load node i does not need to be shedding during the optimization decision-making process. Priority constraints can be conditions determined using the Boolean variables corresponding to the load nodes.

[0055] In some embodiments, each load node corresponds to a Boolean variable, the value of which indicates whether a load shedding is required. Multiple load layers are categorized into three different load layers. Priority constraints include a first priority constraint and a second priority constraint. The first priority constraint is:

[0056] ;

[0057] The second priority constraint is:

[0058] ;

[0059] in, Represents the load nodes in the h-th load layer and the k-th device layer. Boolean variables, 1≤h≤3, 1≤k≤4, Indicates to Invert, for example if ,but ,like ,but .

[0060] Step 210: Verify the load shedding scheme. If the verification passes, send a load shedding command to the protection device based on the load shedding scheme.

[0061] Specifically, the load shedding scheme includes load nodes that need to be partially shelved (referred to as target load nodes). Upon successful verification, the computer equipment sends a load shedding command to the protection device corresponding to the target load node involved in the load shedding scheme. Partial shedding, for example, involves shedding 30% of the target load node's rated active power.

[0062] In the aforementioned distribution network load shedding method, when an anomaly occurs in the distribution network, for each load node in the distribution network, the index values ​​of the load node under multiple evaluation indicators are weighted and calculated to obtain the weighted comprehensive score of the load node; for each device unit in the distribution network, the weighted comprehensive scores of the load nodes in the device unit are averaged to obtain the average comprehensive load score of the device unit. The device unit is obtained by dividing the protection and monitoring devices in the distribution network according to the region. The load node in the device unit refers to the load node corresponding to the protection and monitoring device contained in the device unit; the load nodes are layered according to the weighted comprehensive scores of the load nodes in the distribution network to obtain multiple load layers of different levels, and the device units are layered according to the average comprehensive load score of the device units in the distribution network to obtain multiple device layers of different levels; priority constraints are generated based on the load layer level and the device layer level, and the load shedding scheme of the distribution network is determined based on the priority constraints. The priority constraints are used to limit the shedding priority of the load nodes; the load shedding scheme is verified, and if the verification passes, a load shedding command is sent to the protection and monitoring device based on the load shedding scheme. A novel and practical low-frequency low-voltage load shedding method (i.e., load shedding method) has been implemented, which improves the accuracy of load shedding.

[0063] In some embodiments, each load node corresponds to a Boolean variable, the value of which indicates whether load shedding is required. Determining the load shedding scheme for the distribution network based on priority constraints includes: determining load quantity constraints; and determining the load shedding scheme for the distribution network based on the priority constraints and load quantity constraints. The load quantity constraints are:

[0064] ;

[0065] in, A Boolean variable representing load node i in the distribution network. This represents the amount of load that needs to be removed from load node i during the removal process. is the preset load threshold, and n is the number of load nodes in the distribution network.

[0066] Specifically, This indicates that the load needs to be removed from load node i. This indicates that no load needs to be removed from load node i. The load threshold is used to limit the total load to be removed, ensuring that the total load does not exceed the load threshold.

[0067] In this embodiment, the total load to be cut off is limited by a load threshold in order to avoid cutting off too much load and causing instability in the power distribution network system.

[0068] Under certain disturbances, the power distribution network will experience active power imbalance, leading to a drop in frequency. To prevent system frequency collapse, frequency variation is constrained, and the frequency variation range constraint is shown in the following formula:

[0069] ;

[0070] Neglecting transient changes in the system, the change in active power With frequency change Satisfy the following relationship: Therefore, the frequency variation range constraint of the distribution network system can be transformed into the active power deviation range constraint of the distribution network system, i.e.: Change in active power This refers to the total load removed, thus .

[0071] In some embodiments, determining a load shedding scheme for a distribution network based on priority constraints includes: determining frequency constraints, and determining a load shedding scheme for the distribution network based on the frequency constraints and priority constraints; the frequency constraints are:

[0072] ;

[0073] in, A Boolean variable representing load node i in the distribution network. This represents the amount of load that load node i needs to disconnect during the disconnection process, where n is the number of load nodes in the distribution network. The equivalent frequency regulation effect coefficient of the distribution network. This is the minimum value of the preset frequency variation in the distribution network. This is the maximum value of the preset frequency variation in the distribution network. The frequency constraint is also known as the active power deviation range constraint.

[0074] In some embodiments, and These are ±0.5 Hz (Hertz), i.e. -0.5Hz It is +0.5Hz.

[0075] In this embodiment, constraining frequency variations helps prevent frequency collapse in the power distribution network system.

[0076] Large disturbances in a power system can lead to not only active power loss but also reactive power imbalance, resulting in voltage fluctuations. The voltage at each load node can be used as an indicator of voltage stability, and constraints can be placed on the monitored voltage variation range. .

[0077] In some embodiments, determining a load shedding scheme for a distribution network based on priority constraints includes: determining voltage constraints, and determining a load shedding scheme for the distribution network based on the voltage constraints and priority constraints; the voltage constraints are:

[0078] ;

[0079] in, This represents the maximum value of the voltage change. This represents the maximum value of the voltage change. Let be the voltage change at load node i.

[0080] In this embodiment, constraining the voltage change can reduce the problems caused by voltage fluctuations.

[0081] In some embodiments, determining a load shedding scheme for a distribution network based on priority constraints includes: determining static index constraints, and determining a load shedding scheme for the distribution network based on the static index constraints and priority constraints; the static index constraints include:

[0082] ;

[0083] ;

[0084] ;

[0085] in, This represents the voltage amplitude of load node i as recorded last before the anomaly. For the equivalent reactance of the distribution network, It is the rated voltage of load node i. It is the short-circuit capacity of load node i. It is the change in active power in the distribution network.

[0086] In this embodiment, under the premise of transient stability of the power system, the voltage stability criterion is constrained by static indexes.

[0087] In some embodiments, the voltage range constraints of each node can be linked to load shedding measures. Specifically, for C1 to C5, it can be defined that if the load shedding scheme satisfies the constraint, it is assigned a value of true; otherwise, it is assigned a value of false. Therefore, the Boolean satisfiability problem can be described by the following equation:

[0088]

[0089] Where C1 refers to the load constraint, C2 refers to the priority constraint, C3 refers to the frequency constraint, C4 refers to the voltage constraint, and C5 refers to the static index constraint. For decision-making space A load shedding scheme is proposed. It consists of a series of Boolean variables; S is the decision space. Therefore, the goal is to find a set of Boolean variable values ​​that satisfy all constraints. The load corresponding to this set of Boolean variables is the determined load to be shedding, and the corresponding load shedding amount is 30% of the active power of the load under rated conditions. This can be verified and solved using a "narrowing the decision space + traversal verification" method to find values ​​that satisfy the above formula. The "narrowing the decision space + traversal verification" strategy is as follows:

[0090] 1. Each load has two Boolean values: 0 and 1. Therefore, there are 2^n sets of Boolean values ​​for n load nodes. Based on the constraints C1, C2, and C3, the decision space is narrowed using the CDCL (Conflict-Driven Clause Learning Algorithm) algorithm to obtain several sets of load Boolean values ​​that satisfy the constraints.

[0091] 2. After simulating load shedding according to each group of Boolean values, follow the formula... , and Calculate the static index C5 for voltage stability determination. .

[0092] 3. Continuously try different Boolean values ​​until a set of Boolean values ​​is found that satisfies the voltage constraint condition C4. If multiple sets of Boolean values ​​meet the condition, i.e., multiple load shedding schemes, retain all of them and select one to execute.

[0093] In some embodiments, verifying the load shedding scheme includes: determining the total active power of the actual load shedding based on the load shedding scheme; obtaining the difference between the total active power deficit of the distribution network and the total active power of the actual load shedding to obtain the error; determining that the verification passes if the error is less than or equal to the error threshold, and determining that the verification fails if the error is greater than the error threshold.

[0094] The error threshold is a very small value that only needs to be greater than the error that may exist during the calculation and storage process. It can be selected as 1% of the minimum power value of the connected load.

[0095] Specifically, use This represents the total active power actually cut off (i.e., the change in active power). The total active power deficit of the distribution network system is as described above. ,use Representing error, using Represents the error threshold, then And in If the condition is met, the verification is considered successful; otherwise, the verification is considered unsuccessful.

[0096] In some embodiments, If the data is incorrect, the computer will recalculate the load shedding scheme and repeat the above verification process. If the verification fails after multiple attempts (e.g., 3 times), the computer will issue an error warning to remind maintenance personnel to check the channel.

[0097] In some embodiments, In the case of this situation, the data is deemed to be correct and will be stored. The storage information is shown in Table 4.

[0098] Table 4

[0099]

[0100] In this embodiment, the accuracy of the verification is improved by verifying the difference between the actual total active power cut off and the total active power to be cut off.

[0101] This application substantially implements a novel method for low-frequency, low-voltage load shedding in active distribution networks, enabling precise load shedding. Addressing the technical challenges of the randomness of distributed generation output and the difficulty in coordinating load shedding actions among multiple nodes in active distribution networks, this method utilizes a two-layer architecture of a centralized control station and an integrated load shedding and monitoring device. Based on Boolean satisfiability modeling according to performance ratings, it employs a "reduced decision space + traversal verification" method to determine the load shedding scheme, significantly improving the accuracy of calculating low-frequency, low-voltage load shedding. Furthermore, this application does not require high computing power from the integrated load shedding and monitoring device, balancing effectiveness and practicality, and possessing strong engineering application value. This application also provides a new and effective solution to the shortcomings of current low-frequency, low-voltage load shedding devices, such as low overall coordination and inability to precisely shed load lines, achieving global coordinated control of the load.

[0102] In some embodiments, such as Figure 3 The diagram illustrates a method for disconnecting loads in a power distribution network.

[0103] In some embodiments, the classic IEEE 39-node model is selected, and case simulations are conducted in specific scenarios to analyze the adaptability of this low-frequency, low-voltage load shedding approach for power systems. For example... Figure 4 The diagram shown illustrates the IEEE 39-bus system. The IEEE 39-bus system is a standard test network used in power system analysis, where G represents a generator, and the numbers 1 to 39 represent the electrical node numbers of the power grid. The IEEE 39-bus system comprises 19 load nodes.

[0104] In Case 1, a three-phase short-circuit fault occurs at node 36 at t=1s, causing significant fluctuations in the frequency and voltage of the distribution network system. The integrated protection and monitoring device promptly detects the abnormality and reports it. For these 19 load nodes, the integrated protection and monitoring device is divided into four device layers based on the actual line affiliation. Each load node in each device layer is disconnected at 30% of its corresponding active power. For this simulation case, considering only the electrical distance evaluation metric, the load nodes in the four device layers are divided as follows: "Device Layer 1: Load nodes 15, 16, 21, 23, and 24; Device Layer 2: Load nodes 26, 27, 28, and 29; Device Layer 3: Load nodes 4, 7, 8, 31, 13, and 20; Device Layer 4: Load nodes 25, 39, 3, and 18." Simultaneously, the load nodes are layered into load layers, and the load is divided into three layers based solely on the electrical distance criterion: "Load Layer 1: Load nodes 23, 24, 21, 16, 15, 13, and 18; Load Layer 2: Load nodes 20, 26, 27, 28, and 29; Load Layer 3: Nodes 25, 39, 3, 4, 7, 8, and 31." Based on the load layer and device layer, the CDCL algorithm is used to determine the load nodes that can be cut off: load node 24 in device layer 1 of load layer 1, and load node 4 in device layer 3 of load layer 3.

[0105] Then, calculate the total active power actually cut off from the load and the total active power to be cut off (i.e., the total active power deficit). The calculation result is the total active power actually cut off from the load. Total active power required ,error Where MW stands for Megawatt. If we let... If the value is 0.3MW, it is within the error range. Instructions can be issued and the issued data can be stored. The stored data table is shown in Table 5.

[0106] Table 5

[0107]

[0108] In Case 2, the classic IEEE 39-bus system is still selected. At t=1s, both nodes 6 and 13 experience three-phase short-circuit faults, causing significant fluctuations in the system's frequency and voltage. The integrated protection and monitoring device promptly detects and reports the abnormality. In this case, the load nodes in the four device layers are divided as follows: "Device Layer 1: Load nodes 4, 7, 8, 31, 13, and 15; Device Layer 2: Load nodes 20, 16, 21, 23, and 24; Device Layer 3: Load nodes 25, 39, 3, and 18; Device Layer 4: Load nodes 26, 27, 28, and 29." The load stratification of load nodes is as follows: "Load Layer 1: Load nodes 4, 7, 8, 31, 13, and 15; Load Layer 2: Load nodes 39, 3, 18, 20, 16, 24, and 23; Load Layer 3: Load nodes 25, 26, 27, 28, 29, and 21." Based on the calculation results, the final load shedding scheme will be "canceling load node 13 located in Load Layer 1 of Unit Layer 1, load node 31 located in Load Layer 1 of Unit Layer 1, and load node 39 located in Load Layer 2 of Unit Layer 3." Then, the load shedding scheme is verified by calculating the actual total active power of the load shedding and the total active power to be shedding. The calculation result is the actual total active power of the load shedding. Total active power required ;error If let If the value is 0.3MW, it is outside the error range and needs to be recalculated.

[0109] A load shedding scheme was recalculated, which involved "shedding load node 16 located in load layer 2 of device layer 2, load node 20 located in load layer 2 of device layer 2, and node 26 located in load layer 3 of device layer 4." The recalculated load shedding scheme was then validated to obtain the total active power of the actual shedding load. The total active power needs to be cut off. ;error If let If the value is 0.3MW, it is within the error range. Instructions can be issued and the issued data can be stored. The stored data table is shown in Table 6.

[0110] Table 6

[0111]

[0112] The CDCL algorithm is an efficient algorithm for solving the Boolean satisfiability problem. Its core steps include: Initialization: Reading the input Conjunctive Normal Form (CNF) formula (Equation 29), allocating necessary data structures, and setting initial variable states. Decision: Selecting an unassigned Boolean variable and assigning a value (0 or 1) to its corresponding Boolean variable. The next Boolean variable to be assigned a value is selected based on its activity in conflict analysis, prioritizing variables with high activity to help quickly find conflicts and learn new clauses. Propagation: Updating all relevant clauses with assigned Boolean variables to determine if they conflict with constraints C1, C2, and C3 (any one of them). If a conflict exists, the conflict analysis phase begins; if no conflict exists, the next unassigned variable is selected for assignment and propagation until all Boolean variables are assigned values ​​or a conflict is found. Conflict Analysis and Learning: When a conflict is detected, the conflict is analyzed through backtracking to find the Boolean variable assignment combination that caused the conflict, generating a new clause. This clause is added to the clause set to prevent the same conflict from recurring in subsequent searches. Backtracking: Using the newly generated learning clause, a backtracking point is found and the Boolean variable state is restored, allowing the algorithm to recover from the conflict as quickly as possible and continue searching for other possible solutions. The specific algorithm flow is as follows: Figure 5 As shown.

[0113] In summary, this application realizes a practical approach to low-frequency and low-voltage load shedding in power systems, significantly improving the accuracy of fault line identification, solving the common problem of low overall coordination and inability to accurately disconnect load lines in load shedding devices, and has strong practical value.

[0114] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0115] Based on the same inventive concept, this application also provides a distribution network load shedding device for implementing the aforementioned distribution network load shedding method. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more distribution network load shedding device embodiments provided below can be found in the limitations of the distribution network load shedding method described above, and will not be repeated here.

[0116] In one exemplary embodiment, such as Figure 6 As shown, a power distribution network load shedding device is provided, comprising: a first score determination module 602, a second score determination module 604, a hierarchical division module 606, a shedding scheme determination module 608, and a scheme execution module 610, wherein:

[0117] The first score determination module 602 is used to calculate the weighted comprehensive score of each load node in the distribution network by weighting the index values ​​of the load node under multiple evaluation indicators in the event of an anomaly in the distribution network.

[0118] The second scoring module 604 is used to calculate the average of the weighted comprehensive scores of the load nodes in each device unit in the distribution network to obtain the average comprehensive load score of the device unit. The device unit is obtained by dividing the protection and monitoring devices in the distribution network according to the region. The load node in the device unit refers to the load node corresponding to the protection and monitoring device contained in the device unit.

[0119] The hierarchical division module 606 is used to divide the load nodes into layers according to the weighted comprehensive score of the load nodes in the distribution network to obtain multiple load layers of different levels, and to divide the device units into layers according to the average comprehensive load score of the device units in the distribution network to obtain multiple device layers of different levels.

[0120] The load shedding scheme determination module 608 is used to generate priority constraints based on the load layer hierarchy and device layer hierarchy, and to determine the load shedding scheme of the distribution network based on the priority constraints. The priority constraints are used to limit the shedding priority of load nodes.

[0121] The scheme execution module 610 is used to verify the load shedding scheme. If the verification is successful, it sends a load shedding command to the protection device based on the load shedding scheme.

[0122] In some embodiments, the hierarchical division module 606 is further configured to perform hierarchical division based on the equal-width binning method and the maximum and minimum values ​​of the weighted comprehensive scores of each load node to obtain multiple load layers of different levels; and to perform hierarchical division based on the equal-width binning method and the maximum and minimum values ​​of the average load comprehensive scores of each device unit to obtain multiple device layers of different levels.

[0123] In some embodiments, each load node corresponds to a Boolean variable, the value of which is used to characterize whether load shedding is required. The load shedding scheme determination module 608 is also used to determine load constraints, and based on priority constraints and load constraints, determine the load shedding scheme for the distribution network; the load constraints are: ;in, A Boolean variable representing load node i in the distribution network. This represents the amount of load that needs to be removed from load node i during the removal process. is the preset load threshold, and n is the number of load nodes in the distribution network.

[0124] In some embodiments, the load shedding scheme determination module 608 is further configured to determine frequency constraints, and based on the frequency constraints and priority constraints, determine the load shedding scheme for the distribution network; the frequency constraints are: ;in, A Boolean variable representing load node i in the distribution network. This represents the amount of load that load node i needs to disconnect during the disconnection process, where n is the number of load nodes in the distribution network. The equivalent frequency regulation effect coefficient of the distribution network. This is the minimum value of the preset frequency variation in the distribution network. This is the maximum value of the preset frequency variation in the distribution network.

[0125] In some embodiments, the load shedding scheme determination module 608 is further configured to determine voltage constraints, and based on the voltage constraints and priority constraints, determine the load shedding scheme for the distribution network; the voltage constraints are: ;in, This represents the maximum value of the voltage change. This represents the maximum value of the voltage change. Let be the voltage change at load node i.

[0126] In some embodiments, the load shedding scheme determination module 608 is further configured to determine static index constraints, and based on the static index constraints and priority constraints, determine the load shedding scheme for the distribution network; the static index constraints include:

[0127] ;

[0128] ;

[0129] ;

[0130] in, This represents the voltage amplitude of load node i as recorded last before the anomaly. For the equivalent reactance of the distribution network, It is the rated voltage of load node i. It is the short-circuit capacity of load node i. It is the change in active power in the distribution network.

[0131] In some embodiments, the scheme execution module is further configured to determine the total active power of the actual load shelving based on the load shelving scheme; obtain the difference between the total active power deficit of the distribution network and the total active power of the actual load shelving to obtain the error; determine that the verification passes if the error is less than or equal to the error threshold, and determine that the verification fails if the error is greater than the error threshold.

[0132] Each module in the aforementioned power distribution network load shedding device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module.

[0133] In one exemplary embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 7 As shown, the computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores data related to the power distribution network load shedding method. The I / O interfaces are used for information exchange between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a power distribution network load shedding method.

[0134] In one exemplary embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 8As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the 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 media. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a method for disconnecting loads in a power distribution network. The display unit is used to form a visually visible image and can be a display screen, projection device, or virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0135] Those skilled in the art will understand that Figure 7 and Figure 8 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0136] In one exemplary embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described power distribution network load shedding method.

[0137] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above-described power distribution network load shedding method.

[0138] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described distribution network load shedding method.

[0139] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0140] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0141] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for load shedding in a distribution network, characterized in that, The method includes: In the event of an anomaly in the distribution network, for each load node in the distribution network, the index values ​​of the load node under multiple evaluation indicators are weighted and calculated to obtain the weighted comprehensive score of the load node. For each device unit in the distribution network, the weighted comprehensive score of the load nodes in the device unit is averaged to obtain the average comprehensive load score of the device unit. The device unit is obtained by dividing the protection and monitoring devices in the distribution network according to the region. The load node in the device unit refers to the load node corresponding to the protection and monitoring device included in the device unit. The load nodes are stratified according to the weighted comprehensive score of the load nodes in the distribution network to obtain multiple load layers of different levels. The device units are also stratified according to the average comprehensive load score of the device units in the distribution network to obtain multiple device layers of different levels. Priority constraints are generated based on the hierarchy of the load layer and the hierarchy of the device layer, and the load shedding scheme of the distribution network is determined based on the priority constraints. The priority constraints are used to limit the shedding priority of load nodes. The load shedding scheme is verified, and if the verification passes, a load shedding command is sent to the monitoring device based on the load shedding scheme.

2. The method according to claim 1, characterized in that, The process involves stratifying load nodes based on their weighted composite scores to obtain multiple load layers of different levels, and stratifying device units based on their average load composite scores to obtain multiple device layers of different levels, including: Based on the equal-width binning method and the maximum and minimum values ​​of the weighted comprehensive scores of each load node, the load is divided into multiple different levels. Based on the equal-width binning method and the maximum and minimum values ​​of the average load comprehensive score of each device unit, the device is divided into multiple different levels.

3. The method according to any one of claims 1 to 2, characterized in that, Each load node corresponds to a Boolean variable, and the value of the Boolean variable is used to characterize whether load shedding is required. The process of determining the load shedding scheme for the distribution network based on the priority constraints includes: Determine the load constraints, and based on the priority constraints and the load constraints, determine the load shedding scheme for the distribution network; the load constraints are: ； in, A Boolean variable representing load node i in the distribution network. This represents the amount of load that needs to be removed from load node i during the removal process. is the preset load threshold, and n is the number of load nodes in the distribution network.

4. The method according to any one of claims 1 to 2, characterized in that, The process of determining the load shedding scheme for the distribution network based on the priority constraints includes: Determine the frequency constraints, and based on the frequency constraints and the priority constraints, determine the load shedding scheme for the distribution network; the frequency constraints are: ； in, A Boolean variable representing load node i in the distribution network. This represents the amount of load that load node i needs to disconnect during the disconnection process, where n is the number of load nodes in the distribution network. The equivalent frequency regulation effect coefficient of the distribution network. This is the minimum value of the preset frequency variation in the distribution network. This is the maximum value of the preset frequency variation in the distribution network.

5. The method according to any one of claims 1 to 2, characterized in that, The process of determining the load shedding scheme for the distribution network based on the priority constraints includes: Determine the voltage constraints, and based on the voltage constraints and the priority constraints, determine the load shedding scheme for the distribution network; the voltage constraints are: ； in, This represents the maximum value of the voltage change. This represents the maximum value of the voltage change. Let be the voltage change at load node i.

6. The method according to claim 5, characterized in that, The process of determining the load shedding scheme for the distribution network based on the priority constraints includes: Determine static index constraints, and based on the static index constraints and the priority constraints, determine the load shedding scheme for the distribution network; the static index constraints include: ； ； ； in, This represents the voltage amplitude of load node i as recorded last before the anomaly. For the equivalent reactance of the distribution network, It is the rated voltage of load node i. It is the short-circuit capacity of load node i. It is the change in active power in the distribution network.

7. The method according to any one of claims 1 to 2, characterized in that, The verification of the load shedding scheme includes: Based on the load shedding scheme, determine the total active power of the actual load shedding; The difference between the total active power deficit of the distribution network and the total active power of the actual load shelving is obtained to obtain the error; If the error is less than or equal to the error threshold, the verification is determined to be successful; if the error is greater than the error threshold, the verification is determined to be unsuccessful.

8. A load shedding device for a power distribution network, characterized in that, The device includes: The first score determination module is used to calculate the weighted comprehensive score of each load node in the distribution network under multiple evaluation indicators when an anomaly occurs in the distribution network. The second scoring module is used to calculate the average of the weighted comprehensive scores of the load nodes in each device unit in the distribution network to obtain the average comprehensive load score of the device unit. The device unit is obtained by dividing the protection and monitoring devices in the distribution network according to the region. The load node in the device unit refers to the load node corresponding to the protection and monitoring device included in the device unit. The hierarchical division module is used to divide the load nodes into layers according to the weighted comprehensive score of the load nodes in the distribution network to obtain multiple load layers of different levels, and to divide the device units into layers according to the average comprehensive load score of the device units in the distribution network to obtain multiple device layers of different levels. The load shedding scheme determination module is used to generate priority constraints based on the hierarchy of the load layer and the hierarchy of the device layer, and to determine the load shedding scheme of the distribution network based on the priority constraints. The priority constraints are used to limit the shedding priority of load nodes. The scheme execution module is used to verify the load shedding scheme. If the verification is successful, the module sends a load shedding command to the protection device based on the load shedding scheme.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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