Method for realizing optimal configuration of voltage compensation device of distribution line based on power flow calculation

Abstract

The present application relates to the power distribution technology field, specifically relates to a method for realizing optimal configuration of voltage compensation device of distribution line based on power flow calculation, comprising: obtaining a power flow disturbance set of abnormal nodes in a distribution network and reference nodes of any abnormal node; performing power flow calculation based on the observed voltage curve of all reference nodes to obtain a comprehensive power flow voltage curve; obtaining power flow disturbance nodes and load disturbance nodes by using the difference between the observed voltage curve and the comprehensive power flow voltage curve; obtaining voltage compensation nodes after all lines between the load disturbance nodes are divided into several load disturbance topological structures by the power flow disturbance nodes. The present application makes the voltage compensation device optimally distributed at appropriate grid nodes; avoids the situation that the voltage compensation device cannot suppress the voltage out-of-limit from the root when the out-of-limit or fluctuation of node voltage is simultaneously affected by multi-source load fluctuation and power flow disturbance.

Description

Technical Field

[0001] This invention relates to the field of power grid distribution technology, and more specifically to a method for optimizing the configuration of voltage compensation devices for distribution lines based on power flow calculation. Background Technology

[0002] During operation, the random output of distributed energy sources (photovoltaics, wind power) and load fluctuations in the distribution network can lead to voltage exceeding limits (i.e., voltage too high or too low). To ensure the stable and efficient operation of the distribution network (e.g., to avoid equipment damage, reduce line losses, and improve power quality), voltage compensation is required at the nodes in the distribution network to ensure that the voltage in the grid operates stably according to the set voltage.

[0003] However, the structure of the distribution network is quite complex. For example, when classified by voltage level, the distribution network includes high-voltage distribution network, medium-voltage distribution network, and low-voltage distribution network. When classified by grid structure, it includes ring network (such as single-ring and double-ring networks) and radial network, resulting in complex and diverse power flow. When the voltage of a node exceeds the limit or becomes unstable, it may cause voltage instability in other nodes through power flow propagation. Therefore, the voltage exceeding the limit or instability of a node is affected by both load fluctuation impact and power flow propagation. Moreover, the causes or sources of load fluctuations in the grid are also diverse. After power flow propagation, load fluctuations from different sources are superimposed and difficult to distinguish, making it difficult to find a suitable node for voltage compensation to eliminate the voltage exceeding the limit. Summary of the Invention

[0004] To address the problem of not being able to obtain a suitable voltage compensation location when node voltage is simultaneously affected by load fluctuations from multiple sources and the propagation of power flow in the power grid, this invention provides a method for optimizing the configuration of voltage compensation devices for distribution lines based on power flow calculation.

[0005] The method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation in this invention adopts the following technical solution:

[0006] One embodiment of the present invention provides a method for optimizing the configuration of voltage compensation devices for distribution lines based on power flow calculation. The method includes the following steps:

[0007] Abnormal nodes in the distribution network are screened out, and power flow calculation is performed based on the observed voltage curve of any abnormal node to obtain the power flow voltage curves of all nodes as a function of the observed voltage curve; nodes whose voltage change amplitude in the power flow voltage curve is greater than a first preset threshold are considered as the power flow interference set of the abnormal nodes.

[0008] Any anomalous node is designated as the target node, and the anomalous nodes in the power flow interference set that contain the target node are designated as reference nodes of the target node. Power flow calculation is performed based on the observed voltage curves of all reference nodes to obtain the power flow voltage curve of the target node that varies with the observed voltage curves of all reference nodes, and this curve is designated as the comprehensive power flow voltage curve of the target node.

[0009] When the difference between the observed voltage curve of the target node and the comprehensive power flow voltage curve is less than the second preset threshold, the target node is recorded as a power flow interference node; abnormal nodes other than power flow interference nodes are recorded as load interference nodes.

[0010] All lines between load interference nodes are divided into several load interference topologies by power flow interference nodes, and voltage compensation nodes are obtained on each load interference topology.

[0011] Preferably, the specific steps for screening out abnormal nodes in the distribution network are as follows:

[0012] The preset time period before the current moment is taken as the historical time. The voltage amplitude collected by each node during the historical time period constitutes the observed voltage curve. The average value of all voltage amplitudes in the observed voltage curve of each node is recorded as the average voltage. The preset percentage of the rated voltage of each node is taken as the lower voltage limit and the upper voltage limit respectively. The closed interval formed by the lower voltage limit and the upper voltage limit is taken as the voltage stability interval of each node.

[0013] When the average voltage of any node is outside the voltage stability range of that node, that node is recorded as an abnormal node.

[0014] Preferably, the specific steps for performing power flow calculations based on the observed voltage curve of any one anomalous node to obtain power flow voltage curves for all nodes that vary with the observed voltage curve are as follows:

[0015] For any abnormal node's observed voltage curve, obtain the voltage and power of all nodes in the power grid at the first moment in the observed voltage curve, as well as the topology and line impedance of the power grid, as the initial conditions for power flow calculation. Use the voltage at each moment in the observed voltage curve of the abnormal node as the boundary conditions for the abnormal node, and use Newton's method to solve the power flow equation to obtain the voltage of all nodes other than the abnormal node at each moment. For all moments in the observed voltage curve of the abnormal node, the voltage obtained by performing power flow calculations on each node other than the abnormal node at all moments constitutes the power flow voltage curve.

[0016] The process of calculating the power flow based on the observed voltage curves of all reference nodes to obtain the power flow voltage curve of the target node as it varies with the observed voltage curves of all reference nodes includes the following steps:

[0017] The voltage at each moment in the observed voltage curves of all reference nodes is used as the boundary condition for all reference nodes. The power flow equations are solved using Newton's method to update the voltage of the target node at each moment. For all moments in the observed voltage curves, the voltage of the target node after power flow calculation at all moments constitutes the power flow voltage curve, which is denoted as the composite power flow voltage curve of the target node.

[0018] Preferably, nodes whose voltage variation amplitude in the power flow voltage curve is greater than a first preset threshold are considered as the power flow interference set of the abnormal nodes, and the specific steps include the following:

[0019] For each node other than any abnormal node, obtain the mean value of the amplitude of all voltages in the power flow voltage curve of each node. The absolute value of the difference between the mean value and the rated voltage of each node is recorded as the voltage change amplitude of each node. Nodes whose change amplitude is greater than a first preset threshold are recorded as the power flow interference set of any abnormal node.

[0020] Preferably, the specific steps for obtaining the difference between the observed voltage curve and the integrated power flow voltage curve of the target node are as follows:

[0021] The observed voltage curve and the combined power flow voltage curve of the target node are each divided into several sub-curves;

[0022] The mean value of the voltage amplitude of the i-th sub-curve in the observed voltage curve is denoted as the first mean value of the i-th sub-curve; the mean value of the voltage amplitude of the i-th sub-curve in the composite power flow voltage curve is denoted as the second mean value of the i-th sub-curve; the absolute value of the difference between the first mean value and the second mean value of the i-th sub-curve is denoted as the difference of the i-th sub-curve; the ratio of the mean value of the differences of all sub-curves to the rated voltage of the target node is denoted as the difference between the observed voltage curve and the composite power flow voltage curve of the target node.

[0023] Preferably, all lines between the load interference nodes are divided into several load interference topologies by the power flow interference nodes, including the following specific steps:

[0024] In the power grid topology, the shortest path between any two load interference nodes is obtained; the topology formed by the shortest paths between all load interference nodes is denoted as the first topology; in the first topology, power flow interference nodes and lines directly connected to power flow interference nodes are deleted to obtain several load interference topologies.

[0025] Preferably, the specific steps for obtaining a voltage compensation node on each load interference topology are as follows:

[0026] The ratio of the absolute value of the difference between the average voltage of each abnormal node and the rated voltage of each abnormal node to the rated voltage is denoted as the over-limit amplitude of each abnormal node; the average voltage is the mean of the amplitudes of all voltages in the observed voltage curve of each node.

[0027] In each load disturbance topology, the abnormal node with the largest over-limit amplitude is identified, and voltage compensation is performed at the abnormal node. No voltage compensation is performed on any node other than the abnormal node in each load disturbance topology.

[0028] Preferably, after all lines between load interference nodes are divided into several load interference topologies by power flow interference nodes, the specific steps include the following:

[0029] For any load disturbance topology, the difference between the observed voltage curve of a node on the load disturbance topology and the composite power flow voltage curve is denoted as the load disturbance degree of the node on the load disturbance topology.

[0030] Obtain all endpoints in the load interference topology. For all paths between all endpoints, the load interference levels of all nodes on any path form a sequence. Obtain the minimum value of the load interference level in the sequence, and denote the node corresponding to the minimum value as the node to be optimized. The sum of the load interference levels of all nodes to be optimized is denoteed as the isolation optimization index of the load interference topology. The average value of the isolation optimization indexes of all load interference topologies is denoteed as the load isolation index of the second preset threshold. Obtain the second preset threshold when the load isolation index is at its maximum, and denote it as the updated second preset threshold.

[0031] When the difference between the observed voltage curve of the target node and the integrated power flow voltage curve is less than the updated second preset threshold, the target node is recorded as a power flow interference node; abnormal nodes other than power flow interference nodes are recorded as load interference nodes; all lines between load interference nodes are divided into several load interference topologies by power flow interference nodes, and voltage compensation nodes are obtained on each load interference topology.

[0032] Preferably, the second preset threshold at which the load isolation index is maximized is denoted as the updated second preset threshold, and the specific steps include the following:

[0033] Set a threshold range, and let the second preset threshold traverse all values ​​within the threshold range with a preset step size. After traversing to a value, the value is taken as the value of the second preset threshold, and the load isolation index of the second preset threshold is obtained. After the traversal is completed, the load isolation index of the second preset threshold under different values ​​is obtained. The value of the second preset threshold when the load isolation index is the largest is obtained and recorded as the updated second preset threshold.

[0034] Preferably, the specific steps for obtaining the shortest path between any two load interference nodes are as follows:

[0035] Obtain all distribution lines between any two load interference nodes. If a distribution line passes through a node other than the abnormal node, remove that distribution line. Among the remaining distribution lines, select the distribution line with the smallest total impedance and use it as the shortest path.

[0036] The beneficial effects of the technical solution of the present invention are:

[0037] This invention uses anomalous nodes in the power flow interference set that include the target node as reference nodes for the target node; power flow calculations are performed based on the observed voltage curves of all reference nodes to obtain the comprehensive power flow voltage curve of the target node; based on the difference between the observed voltage curve of the target node and the comprehensive power flow voltage curve, anomalous nodes are classified into power flow interference nodes and load interference nodes. All lines between load interference nodes are divided into several load interference topologies by the power flow interference nodes, and voltage compensation nodes are obtained on each load interference topology. This process isolates voltage exceedances caused by load fluctuations in the power grid. This isolation involves two aspects: firstly, distinguishing nodes significantly affected by load fluctuations (load interference nodes) from those significantly affected by power flow propagation (power flow interference nodes); and secondly, isolating nodes significantly affected by load fluctuations from different sources into different parts (i.e., different load interference topologies). The load fluctuations in these different parts have a degree of independence, ultimately allowing for separate voltage compensation for each independent load fluctuation impact, improving voltage compensation efficiency (i.e., optimally distributing voltage compensation devices at suitable power grid nodes). This prevents situations where node voltage exceedances or fluctuations are simultaneously caused by multiple load fluctuations and power flow interference, where the voltage compensation device cannot fundamentally suppress voltage exceedances. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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 creative effort.

[0039] Figure 1 This is a flowchart illustrating the steps of a method for optimizing the configuration of a power distribution line voltage compensation device based on power flow calculation, as provided in an embodiment of the present invention. Detailed Implementation

[0040] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation proposed by the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0042] The following description, in conjunction with the accompanying drawings, details the specific scheme of the method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation provided by the present invention.

[0043] Example 1:

[0044] Please see Figure 1 The diagram illustrates a flowchart of a method for optimizing the configuration of a power distribution line voltage compensation device based on power flow calculation, according to an embodiment of the present invention. The method includes the following steps:

[0045] Step S101: Record the nodes in the distribution network that exceed the voltage limit during the historical period as abnormal nodes, and record the observed voltage curves of the abnormal nodes.

[0046] Several nodes are set in the power distribution network. In this embodiment, the connection port between the power equipment and the distribution line is used as the node. The power equipment includes substation busbars, distribution cabinets, inverters, etc. In other embodiments, nodes can be set according to the specific power grid structure. This embodiment does not limit the nodes.

[0047] Electronic voltage transformers are installed at each node to collect the node's voltage. In this embodiment, the voltage is a complex number (representing voltage amplitude and phase). A power meter and an electronic current transformer are also installed at each node, allowing the user to measure the power (including active and reactive power) at each node. Furthermore, the distribution line directly connecting any two adjacent nodes is simply referred to as the line between any two adjacent nodes. In this example, the impedance of each line is considered a known quantity; in some embodiments, electronic current transformers may also be installed on each line to measure the current (current in complex format, representing current amplitude and phase). The ratio of the voltage difference between the two nodes at each end of the line to the current is used as the impedance of each line (the impedance is also a complex number, representing resistance and reactance). The above process is used to measure the electrical state of each node to facilitate subsequent power flow analysis. The specific methods for measuring the electrical state of each node are well-known and will not be described in detail in this embodiment.

[0048] In this embodiment, the voltage is sampled every 0.2 seconds. Additionally, each node is assigned a rated voltage (the rated voltage is a real number representing the voltage level at which the node operates stably over a long period). In this embodiment, 96% of the rated voltage is used as the lower voltage limit, and 104% of the rated voltage is used as the upper voltage limit. The closed interval formed by the lower and upper voltage limits is used as the voltage stability interval for each node. In other embodiments, the voltage stability interval for each node can be set to other intervals; this embodiment does not impose such a limitation.

[0049] Within the historical time frame preceding the current moment (e.g., within one minute prior to the current moment, including the current moment), the voltage collected by each node constitutes the observed voltage curve. In this embodiment, each 0.2 seconds represents a moment, with the horizontal axis of the observed voltage curve representing the moment and the vertical axis representing the voltage amplitude at each moment.

[0050] Specifically, if the power grid topology changed within one minute prior to the current moment (e.g., the on / off state of a tie switch in a distribution line was changed), then the period from the topology change to the current moment will be considered historical time. Specifically, if the power grid changes at the current moment, then the subsequent steps of this embodiment will not be implemented at the current moment.

[0051] The average voltage is the mean value of the amplitudes of all voltages in the observed voltage curve of each node.

[0052] When the average voltage of any node is outside the stable voltage range of that node, it indicates that the voltage of that node is out of limit (i.e., the voltage is too high or too low), and that node is recorded as an abnormal node.

[0053] In this embodiment, the ratio of the absolute value of the difference between the average voltage of each abnormal node and the rated voltage of each abnormal node to the rated voltage is recorded as the over-limit amplitude of each abnormal node.

[0054] The voltage instability of the abnormal node is caused by factors such as the random output of distributed energy sources (photovoltaic and wind power) and load fluctuations in the power grid, which lead to voltage exceeding the limit. For ease of description, the following description will take load fluctuations as an example.

[0055] Step S102: Perform power flow calculation based on the observed voltage curve of any abnormal node to obtain the power flow voltage curves of all nodes as they change with the observed voltage curve; nodes whose voltage change amplitude in the power flow voltage curve is greater than a first preset threshold are considered as the power flow interference set of the abnormal node.

[0056] This implementation takes into account the complex structure of the distribution network. For example, when classified by voltage level, the distribution network includes high-voltage distribution network, medium-voltage distribution network and low-voltage distribution network. When classified by grid structure, it includes ring network (such as single ring and double ring network) and radial network, which makes the power flow of the grid complex and diverse. The instability of node voltage, or the change of node voltage, may be affected by load fluctuation factors, as well as by changes in grid power flow and propagation effects.

[0057] The power flow voltage curve described in this embodiment represents the voltage changes of other nodes affected by the power flow changes and propagation of the power flow when the voltage of a single abnormal node changes according to the observed voltage curve.

[0058] The set of power flow disturbances of an abnormal node contains several nodes. The set of power flow disturbances of an abnormal node represents other nodes whose voltage changes significantly due to the change and propagation of the power flow caused by a single abnormal node. In other words, the nodes in the set of power flow disturbances are significantly affected by the change and propagation of the power flow.

[0059] As an example, power flow calculations are performed based on the observed voltage curve of any anomalous node to obtain power flow voltage curves for all nodes that vary with the observed voltage curve. The method includes:

[0060] For any anomalous node's observed voltage curve, obtain the voltage and power of all nodes in the power grid at the first moment in the observed voltage curve, as well as the power grid's topology and line impedance, as the initial conditions of the power grid. Use the voltage at each moment in the observed voltage curve of the anomalous node as the known quantity (or boundary condition) of the anomalous node, and use Newton's method to solve the power flow equations to update the voltage of all nodes except the anomalous node at each moment. For all moments in the observed voltage curve of the anomalous node, the voltage obtained by performing power flow calculations on each node except the anomalous node at all moments constitutes the power flow voltage curve.

[0061] The specific methods for calculating power flow are well known. This embodiment may use other methods for power flow calculation, such as the Newton-Raphson method. This embodiment does not make specific limitations or elaborate on them.

[0062] As an example, the method for obtaining the power flow interference set of abnormal nodes is as follows:

[0063] For each node other than the abnormal node, the following processing is performed:

[0064] Obtain the mean value of all voltage amplitudes in the power flow voltage curve of each node. The absolute value of the difference between this mean value and the rated voltage of each node is recorded as the voltage variation amplitude of each node. The set of all nodes whose variation amplitude is greater than a first preset threshold th1 is recorded as the power flow interference set of that abnormal node.

[0065] This embodiment uses th1 equal to 3% of the rated voltage of each node as an example.

[0066] Step S103: Denote any abnormal node as the target node, and denote the abnormal nodes in the power flow interference set that contain the target node as the reference nodes of the target node; perform power flow calculation based on the observed voltage curves of all reference nodes to obtain the power flow voltage curve of the target node that varies with the observed voltage curves of all reference nodes, and denote it as the comprehensive power flow voltage curve of the target node.

[0067] The above obtains the power flow interference set for each abnormal node. The nodes in the power flow interference set will experience significant voltage changes due to the power flow alteration caused by the abnormal node.

[0068] Any abnormal node is designated as the target node. If the power flow interference set of any abnormal node other than the target node contains the target node, then the abnormal node is marked as the reference node of the target node. All reference nodes of the target node are marked among all abnormal nodes.

[0069] A reference node refers to a target node whose voltage changes significantly due to power flow alterations caused by multiple reference nodes. In other words, voltage fluctuations at multiple reference nodes can affect the voltage of the same node (i.e., the target node) through changes and propagation of power flow across the grid.

[0070] The combined power flow voltage curve of the target node represents the voltage change of the target node when voltage fluctuations at multiple reference nodes affect it through changes and propagation of power flow across the power grid.

[0071] As an example, power flow calculations are performed based on the observed voltage curves of all reference nodes to obtain the power flow voltage curve of the target node as it varies with the observed voltage curves of all reference nodes. This curve is denoted as the composite power flow voltage curve of the target node. The methods include:

[0072] For any abnormal node's observed voltage curve, obtain the voltage and power of all nodes in the power grid at the first moment in the observed voltage curve, as well as the power grid's topology and line impedance, as the initial conditions of the power grid; use the voltage of each moment in the observed voltage curves of all reference nodes as known quantities (or boundary conditions) for all reference nodes, and use Newton's method to solve the power flow equations to update the target node's voltage at each moment; for all moments in the observed voltage curve, the voltage of the target node obtained after performing power flow calculations at all moments constitutes the power flow voltage curve, which is denoted as the target node's comprehensive power flow voltage curve.

[0073] Step S104: When the difference between the observed voltage curve of the target node and the comprehensive power flow voltage curve is less than the second preset threshold, the target node is recorded as a power flow interference node; abnormal nodes other than the power flow interference node are recorded as load interference nodes.

[0074] The smaller the difference between the observed voltage curve of the target node and the comprehensive power flow voltage curve, the more likely that the impact of other nodes (i.e., reference nodes) on the voltage of the target node through changes and propagation of power flow is the same as or similar to the actual voltage changes of the target node in actual power grid operation. This indicates that the voltage fluctuations or changes of the target node are mainly affected by changes and propagation effects of power flow. In this embodiment, when the difference between the observed voltage curve of the target node and the comprehensive power flow voltage curve is less than the second preset threshold th2, the target node is recorded as a power flow interference node.

[0075] Abnormal nodes other than power flow interference nodes are less affected by power flow changes and propagation effects, while load fluctuations or load shocks have a greater impact on these nodes. In this embodiment, abnormal nodes other than power flow interference nodes are referred to as load interference nodes.

[0076] As an optional example, the method for obtaining the difference between the observed voltage curve of the target node and the integrated power flow voltage curve is as follows:

[0077] The mean value of the amplitude of all voltages in the observed voltage curve of the target node is denoted as U1, and the mean value of the amplitude of all voltages in the combined power flow voltage curve is denoted as U2. The ratio of the absolute value of the difference between U1 and U2 to the rated voltage of the target node is denoted as the difference between the observed voltage curve of the target node and the combined power flow voltage curve.

[0078] As a preferred example, the method for obtaining the difference between the observed voltage curve of the target node and the composite power flow voltage curve is as follows:

[0079] The observed voltage curve and the combined power flow voltage curve are each divided into several (e.g., 5) sub-curves.

[0080] The mean value of the voltage amplitude of the i-th sub-curve in the observed voltage curve is denoted as the first mean value of the i-th sub-curve. The mean value of the voltage amplitude of the i-th sub-curve in the composite power flow voltage curve is denoted as the second mean value of the i-th sub-curve; the absolute value of the difference between the first mean value and the second mean value of the i-th sub-curve is denoted as the difference of the i-th sub-curve; the ratio of the mean value of the differences of all sub-curves to the rated voltage of the target node is denoted as the difference between the observed voltage curve of the target node and the composite power flow voltage curve.

[0081] In special cases, when the observed voltage curve and the integrated power flow voltage curve are not equally divided, the remaining undivided curve segments are still treated as a sub-curve.

[0082] This embodiment uses th2 equal to 0.1 as an example for description. In other embodiments, th2 can be set to other values. This embodiment does not impose specific limitations.

[0083] Step S105: All lines between load interference nodes are divided into several load interference topologies by power flow interference nodes, and voltage compensation nodes are obtained on each load interference topology.

[0084] In the power grid topology, the shortest path between any two load disturbance nodes is obtained. The topology formed by the shortest paths between all load disturbance nodes is denoted as the first topology graph, which indicates that the impact of load fluctuations will propagate along this first topology graph, eventually leading to abnormal nodes in the power grid that exceed voltage limits.

[0085] As an example, the method for obtaining the shortest path between any two load interference nodes includes:

[0086] Obtain all distribution lines between any two load interference nodes. If a distribution line passes through any node other than the abnormal node (i.e., no node with voltage exceeding the limit), remove that distribution line. Among the remaining distribution lines, select the one with the smallest total impedance, and the path traversed by that distribution line is taken as the shortest path. Specifically, if there are no remaining distribution lines, the two load interference nodes are not connected in the first topology diagram.

[0087] Furthermore, in the first topology diagram, power flow interference nodes and lines directly connected to them are removed. The resulting load interference propagation structure comprises at least one sub-topology. There are no line connections between different sub-topologies, and load fluctuations between them are independent. For example, one sub-topology may be impacted by some load fluctuations, while another sub-topology may be impacted by other load fluctuations. The sources of load fluctuations in these two sub-topologies are considered different and independent. In this embodiment, each sub-topology is referred to as a load interference topology.

[0088] Different voltage compensation devices are used for voltage compensation in lines with different load interference topologies.

[0089] As an example, different voltage compensation devices are used for voltage compensation in lines with different load interference topologies, including the following methods:

[0090] Voltage compensation devices are installed at each node in the power distribution network.

[0091] In each load disturbance topology, the abnormal node with the largest over-limit amplitude is identified, and voltage compensation is performed at the abnormal node (i.e., the voltage compensation device is activated for compensation) so that the voltage at the abnormal node is restored to the rated voltage. Other nodes in each load disturbance topology are not subjected to voltage compensation (i.e., the voltage compensation device is disabled or stopped for compensation).

[0092] In some embodiments, if no voltage compensation device is installed at the abnormal node, then the abnormal node with the second largest over-limit amplitude is identified, and voltage compensation is performed at that node. If the second largest abnormal node also lacks a voltage compensation device, then voltage compensation is performed at the abnormal node with the third largest over-limit amplitude, and so on. Specifically, if no voltage compensation device is installed in any load interference topology, then grid maintenance personnel are immediately notified to install a voltage compensation device at the abnormal node with the largest over-limit amplitude.

[0093] In other embodiments, voltage compensation can be performed on several (e.g., two) abnormal nodes with the largest out-of-limit amplitude in each load disturbance topology.

[0094] As an example, the method for voltage compensation is as follows:

[0095] This embodiment uses a dynamic compensation device (STATCOM / SVG) for compensation. At the current moment, when the voltage amplitude of the abnormal node is less than the rated voltage, the dynamic compensation device uses capacitive compensation mode; when the voltage amplitude of the abnormal node is greater than the rated voltage, the dynamic compensation device uses inductive compensation mode. If the voltage amplitude of the abnormal node is equal to the rated voltage, no compensation is performed.

[0096] The method of using a voltage compensation device to compensate nodes is a well-known technology, and will not be described in detail in this embodiment. Other voltage compensation devices may also be used in other embodiments. Since the purpose of this embodiment is to obtain the nodes that need voltage compensation, the voltage compensation device or specific method is not limited.

[0097] Thus, in this embodiment, at the current moment, the voltage exceeding the limit caused by load fluctuations in the power grid is isolated. This isolation refers to two aspects: firstly, distinguishing between nodes significantly affected by load fluctuations (load interference nodes) and nodes significantly affected by power flow propagation (power flow interference nodes); secondly, isolating nodes significantly affected by load fluctuations into different parts (i.e., different load interference topologies), so that the independent load fluctuation impacts can be compensated for voltage separately, improving voltage compensation efficiency (i.e., voltage compensation devices are optimally distributed at suitable power grid nodes).

[0098] Furthermore, all the above steps are repeated every preset time interval (e.g., every 10 minutes) so that the voltage compensation position can be continuously updated according to the operating status of the power grid.

[0099] This concludes the example.

[0100] Example 2:

[0101] The difference between this embodiment and Embodiment 1 is that this embodiment takes into account that if the second preset threshold th2 is not set properly, it will lead to an inappropriate division of power flow interference nodes and load interference nodes. In addition, the nodes are affected by power flow propagation and multi-source load fluctuations at the same time, making it difficult to use a fixed threshold (i.e., the second preset threshold th2) to divide power flow interference nodes and load interference nodes. It is impossible to fully isolate different load interferences, which will result in the voltage compensation device's compensation method being suboptimal.

[0102] This embodiment provides an initial value for a second preset threshold th2. Then, several load interference topologies are obtained using Embodiment 1.

[0103] For any load disturbance topology, all nodes on the load disturbance topology are load disturbance nodes. The difference between the observed voltage curve of a load disturbance node and the composite power flow voltage curve is denoted as the load disturbance degree of the node on the load disturbance topology.

[0104] Obtain all endpoints in the load disturbance topology (i.e., nodes connected to only one other node). For all paths between all endpoints, first remove paths with a length less than 3 (i.e., paths with 4 or more nodes). Then, construct a sequence of load disturbance levels for all nodes on any path. Obtain the minimum value of the load disturbance level in this sequence. The node corresponding to the minimum value is designated as the node to be optimized. The node to be optimized represents the node whose load disturbance level gradually decreases. The lower the load disturbance level of the node, the more it needs to be disconnected at the node to isolate the impact of load fluctuations.

[0105] In some embodiments, the sequence is Gaussian filtered using a Gaussian filter kernel of length 3 before the minimum value is obtained.

[0106] Furthermore, the sum of the load interference levels of all nodes to be optimized is recorded as the isolation optimization index of the load interference topology, and the average of the isolation optimization indices of all load interference topologies is recorded as the load isolation index of the second preset threshold.

[0107] The second preset threshold at which the load isolation index is maximized is recorded as the updated second preset threshold. Under the updated second preset threshold, the isolation optimization index for different load interference topologies is relatively large, and each load interference topology does not need to be further disconnected to isolate the impact of load fluctuations.

[0108] This embodiment utilizes the updated second preset threshold to achieve step S105 in embodiment one.

[0109] As an example, the second preset threshold at which the load isolation metric is maximized is denoted as the updated second preset threshold, and includes:

[0110] In this embodiment, a threshold range is set (e.g., [0.05, 0.3]). In this embodiment, an initial value of th2 is set to 0.05. The load isolation index of the second preset threshold th2 is obtained according to the method described above in this embodiment.

[0111] Then, starting from the initial value, th2 iterates through all values ​​within the threshold range with a step size of 0.05. After each value is iterated through, it is used as the value of the second preset threshold th2. The load isolation index of the second preset threshold th2 is obtained according to the above method.

[0112] After the traversal is completed, the load isolation index of th2 under different values ​​is obtained. The value of th2 when the load isolation index is at its maximum is obtained and recorded as the updated second preset threshold.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for optimizing the configuration of voltage compensation devices for power distribution lines based on power flow calculation, characterized in that, The method includes the following steps: screening out abnormal nodes in the distribution network; performing power flow calculation based on the observed voltage curve of any abnormal node to obtain the power flow voltage curves of other nodes besides the abnormal node as a function of the observed voltage curve; nodes whose voltage change amplitude in the power flow voltage curve is greater than a first preset threshold constitute the power flow interference set of the abnormal node; designating any abnormal node as the target node, and using the abnormal nodes in the power flow interference set that include the target node as reference nodes for the target node; performing power flow calculation based on the observed voltage curves of all reference nodes to obtain the power flow voltage curve of the target node as a function of the observed voltage curves of all reference nodes, and designating it as the comprehensive power flow voltage curve of the target node; when the difference between the observed voltage curve of the target node and the comprehensive power flow voltage curve is less than a second preset threshold, the target node is designated as a power flow interference node; abnormal nodes other than the power flow interference nodes are designated as load interference nodes; all lines between load interference nodes are divided into several load interference topologies by the power flow interference nodes, and voltage compensation nodes are obtained on each load interference topology; All lines between the load interference nodes are divided into several load interference topologies by the power flow interference nodes, including the following specific steps: In the power grid topology, the shortest path between any two load interference nodes is obtained; the topology formed by the shortest paths between all load interference nodes is denoted as the first topology; in the first topology, power flow interference nodes and lines directly connected to power flow interference nodes are deleted to obtain several load interference topologies. The specific steps for obtaining the shortest path between any two load interference nodes are as follows: Obtain all distribution lines between any two load interference nodes. If a distribution line passes through a node other than the abnormal node, remove that distribution line. Among the remaining distribution lines, select the distribution line with the smallest total impedance and use it as the shortest path.

2. The method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation according to claim 1, characterized in that, The specific steps for filtering out abnormal nodes in the power distribution network are as follows: The preset time period before the current moment is taken as the historical time. The voltage amplitude collected by each node during the historical time period constitutes the observed voltage curve. The average value of all voltage amplitudes in the observed voltage curve of each node is recorded as the average voltage. The preset percentage of the rated voltage of each node is taken as the lower voltage limit and the upper voltage limit respectively. The closed interval formed by the lower voltage limit and the upper voltage limit is taken as the voltage stability interval of each node. When the average voltage of any node is outside the voltage stability range of that node, that node is recorded as an abnormal node.

3. The method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation according to claim 1, characterized in that, The process of calculating the power flow based on the observed voltage curves of all reference nodes to obtain the power flow voltage curve of the target node as it varies with the observed voltage curves of all reference nodes includes the following steps: The voltage at each moment in the observed voltage curves of all reference nodes is used as the boundary condition for all reference nodes. The power flow equations are solved using Newton's method to update the voltage of the target node at each moment. For all moments in the observed voltage curve, the voltage obtained by performing power flow calculations on the target node at all moments constitutes the power flow voltage curve, which is denoted as the composite power flow voltage curve of the target node.

4. The method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation according to claim 1, characterized in that, The specific steps involved in performing power flow calculations based on the observed voltage curve of any anomalous node to obtain the power flow voltage curves of other nodes besides the anomalous node as a function of the observed voltage curve are as follows: For any abnormal node's observed voltage curve, obtain the voltage and power of all nodes in the power grid at the first moment in the observed voltage curve, as well as the power grid's topology and line impedance, as the initial conditions for power flow calculation. Use the voltage at each moment in the observed voltage curve of the abnormal node as the boundary conditions for the abnormal node, and use Newton's method to solve the power flow equations to obtain the voltage of all nodes other than the abnormal node at each moment. For all moments in the observed voltage curve of the abnormal node, the voltage obtained by performing power flow calculations on each node other than the abnormal node at all moments constitutes the power flow voltage curve.

5. The method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation according to claim 1, characterized in that, Nodes whose voltage variation in the power flow voltage curve exceeds a first preset threshold are considered as the set of power flow disturbances of the abnormal nodes, and the specific steps include the following: For each node other than any abnormal node, obtain the mean value of the amplitude of all voltages in the power flow voltage curve of each node. The absolute value of the difference between the mean value and the rated voltage of each node is recorded as the voltage change amplitude of each node. Nodes whose change amplitude is greater than a first preset threshold are recorded as the power flow interference set of any abnormal node.

6. The method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation according to claim 1, characterized in that, The specific steps for obtaining the difference between the observed voltage curve and the composite power flow voltage curve of the target node are as follows: The observed voltage curve and the combined power flow voltage curve of the target node are each divided into several sub-curves; The mean value of the voltage amplitude of the i-th sub-curve in the observed voltage curve is denoted as the first mean value of the i-th sub-curve; the mean value of the voltage amplitude of the i-th sub-curve in the composite power flow voltage curve is denoted as the second mean value of the i-th sub-curve; the absolute value of the difference between the first mean value and the second mean value of the i-th sub-curve is denoted as the difference of the i-th sub-curve; the ratio of the mean value of the differences of all sub-curves to the rated voltage of the target node is denoted as the difference between the observed voltage curve and the composite power flow voltage curve of the target node.

7. The method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation according to claim 1, characterized in that, The specific steps for obtaining voltage compensation nodes on each load interference topology are as follows: The ratio of the absolute value of the difference between the average voltage of each abnormal node and the rated voltage of each abnormal node to the rated voltage is denoted as the over-limit amplitude of each abnormal node; the average voltage is the mean of the amplitudes of all voltages in the observed voltage curve of each node. In each load disturbance topology, the abnormal node with the largest over-limit amplitude is identified, and voltage compensation is performed at the abnormal node. No voltage compensation is performed on any node other than the abnormal node in each load disturbance topology.

8. The method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation according to claim 1, characterized in that, After all lines between load interference nodes are divided into several load interference topologies by power flow interference nodes, the specific steps include the following: For any load disturbance topology, the difference between the observed voltage curve of a node on the load disturbance topology and the composite power flow voltage curve is denoted as the load disturbance degree of the node on the load disturbance topology. Obtain all endpoints in the load interference topology. For all paths between all endpoints, the load interference levels of all nodes on any path form a sequence. Obtain the minimum value of the load interference level in the sequence. The node corresponding to the minimum value is recorded as the node to be optimized. The sum of the load interference levels of all nodes to be optimized is recorded as the isolation optimization index of the load interference topology. The average value of the isolation optimization index of all load interference topologies is recorded as the load isolation index of the second preset threshold. The second preset threshold when the load isolation index is at its maximum is obtained and recorded as the updated second preset threshold. When the difference between the observed voltage curve of the target node and the integrated power flow voltage curve is less than the updated second preset threshold, the target node is recorded as a power flow interference node. Abnormal nodes other than power flow interference nodes are denoted as load interference nodes. All lines between load interference nodes are divided into several load interference topologies by power flow interference nodes, and voltage compensation nodes are obtained on each load interference topology.

9. The method for optimizing the configuration of power distribution line voltage compensation devices based on power flow calculation according to claim 8, characterized in that, The specific steps involved in obtaining the second preset threshold when the load isolation index is at its maximum, denoted as the updated second preset threshold, are as follows: Set a threshold range, and let the second preset threshold traverse all values ​​within the threshold range with a preset step size. After traversing to a value, the value is taken as the value of the second preset threshold, and the load isolation index of the second preset threshold is obtained. After the traversal is completed, the load isolation index of the second preset threshold under different values ​​is obtained. The value of the second preset threshold when the load isolation index is the largest is obtained and recorded as the updated second preset threshold.

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