Rural power distribution network adjusting method and system considering load damage and node coupling degree

Abstract

The invention discloses a rural power distribution network adjusting method and system considering load damage and node coupling degree. The method comprises the steps of collecting voltage, current, injection active power and injection reactive power of each load node of a power distribution network; based on the dynamic impedance matrix, obtaining an electrical distance between the load nodes, and according to the electrical distance between the load nodes, carrying out partitioning on the load nodes by adopting an agglomerated hierarchical clustering method; in any partition, a reactive power compensation node selection model is established according to the impedance mode margin and the node comprehensive coupling degree, and reactive power compensation nodes in the partition are determined according to the model; based on the least square method, a fitting model of the reactive compensation capacity in the partition and the impedance modulus margin at the reactive compensation node is established, and when the minimum value of the impedance modulus margin at the reactive compensation node is smaller than an impedance modulus margin threshold value, the impedance modulus margin threshold value is used as a benchmark, and based on the fitting model, the impedance modulus margin is calculated; and determining the reactive compensation capacity configured by the reactive compensation node in the partition. According to the invention, the problems of uneven load, large power loss and unstable voltage of the rural power distribution network are solved.

Description

Technical Field

[0001] The present invention relates to the field of electric power, and in particular to a rural distribution network regulation method and system taking into account load damage and node coupling degree. Background Art

[0002] With the development of social economy and the gradual improvement of people's living standards, especially the rapid development of urbanization, high-power electrical appliances such as air conditioners and induction cookers have become very popular in rural areas, and industrial production has also changed from the original decentralized to centralized. Although the rural power grid has undergone several phases of transformation, it still cannot meet the growing demand for electricity. In particular, there are some distribution substations. Due to the seasonality and concentration of industrial and agricultural production, different distribution nodes have different seasonal electricity consumption characteristics, which makes it difficult for the distribution node capacity to meet the surge in load demand, resulting in low voltage nodes or even node damage, thereby endangering the safety and stability of electricity use in the entire substation.

[0003] The upgrading and transformation of rural power grids has been continuously strengthened, but with the great investment in distribution networks, the seasonal load has obvious peak characteristics, and the effect of simply increasing the distribution capacity is minimal. This has further led to many low voltage situations, which has seriously troubled the power supply load area. There is a lack of effective load regulation methods between different nodes for seasonal loads. In the prior art, the low voltage caused by seasonal load fluctuations in rural distribution networks is mainly alleviated by upgrading rural aging line equipment and increasing the capacity of distribution networks. However, only by upgrading the physical equipment of electricity to ensure that the distribution network meets the peak demand for regional electricity consumption, there are disadvantages such as high cost and low elasticity, which cannot meet the growing regional electricity demand.

[0004] The connection of reactive power compensation devices to the power grid can alleviate the pressure of reactive power generation from power plants to a certain extent, thereby reducing line and equipment losses, improving the voltage stability of the power grid, increasing the power transmission capacity and preventing voltage collapse at weak nodes. Reactive power compensation configuration is actually a problem of finding the optimal solution for a multi-objective function that requires consideration of multiple factors. The objective function of reactive power compensation optimization configuration mainly includes the minimum economic cost, minimum active power loss, minimum voltage deviation, maximum voltage stability margin, and comprehensive multi-objective optimization. When the power system approaches its operating limit, the voltage stability problem is particularly prominent, and reactive power compensation needs to take improving voltage stability as the main configuration goal. Summary of the invention

[0005] The purpose of the present invention is to provide a rural distribution network regulation method and system taking into account load damage and node coupling, which solves the problems of uneven load, large power loss and unstable voltage in the rural distribution network, realizes more reliable and efficient power distribution, improves the power supply quality, and thus brings significant improvement to the power supply in rural areas.

[0006] The present invention adopts the following technical solution.

[0007] The present invention proposes a rural distribution network regulation method considering load damage and node coupling, comprising:

[0008] Collect the voltage, current, injected active power and injected reactive power of each load node in the distribution network;

[0009] The electrical distance between load nodes is obtained based on the dynamic impedance matrix, and the load nodes are partitioned using the agglomerative hierarchical clustering method according to the electrical distance between load nodes.

[0010] In any partition, a reactive compensation node selection model is established according to the impedance modulus margin and the comprehensive coupling degree of the node, and the reactive compensation nodes in the partition are determined according to the model; based on the least squares method, a fitting model of the reactive compensation capacity in the partition and the impedance modulus margin at the reactive compensation node is established; when the minimum value of the impedance modulus margin at the reactive compensation node is less than the impedance modulus margin threshold, the reactive compensation capacity configured for the reactive compensation node in the partition is determined based on the fitting model with the impedance modulus margin threshold as the benchmark.

[0011] The dynamic mutual impedance satisfies the following relationship:

[0012]

[0013] In the formula, are the voltage change at node i and the current change at node j respectively; is the dynamic mutual impedance between node i and node j; λ is the injection power parameter;

[0014] When i=j, it is dynamic self-impedance;

[0015] The dynamic impedance matrix of the distribution network is established using the dynamic mutual impedance and dynamic self-impedance of each node.

[0016] The ratio of dynamic self-impedance to dynamic mutual impedance As the projection position of load node i on the plane where load node j is located in n-dimensional space, is the element in the ith row and jth column of the dynamic impedance matrix, is the element in the jth row and jth column of the dynamic impedance matrix;

[0017] Using the geometric method, the electrical distance between load nodes is calculated using the following relationship:

[0018]

[0019] Where, L ij is the electrical distance between load node i and load node j; di1 d i2 ,……,d in are the projection positions of node i on the 1st, 2nd, ..., nth planes in the n-dimensional space; d j1 d j2 ,……,d jn are the projection positions of node j on the 1st, 2nd, …, nth planes in the n-dimensional space respectively; n is the number of nodes.

[0020] According to the electrical distance between load nodes, the load nodes are partitioned using the agglomerative hierarchical clustering method, including:

[0021] Treat all load nodes as n separate classes, calculate the electrical distances between the classes, and obtain the symmetric distance matrix L = (L ij ) n×n ;

[0022] The matrix L = (L ij ) n×n The element with the smallest non-diagonal median value min(L ij )(i≠j) are merged into a new class, and the matrix L=(L ij ) n×n The rows and columns corresponding to the two classes in the symmetric distance merge matrix L′ (n-2)×(n-2) ;

[0023] The minimum sum of squares of deviations method is used to calculate the inter-class distance between the new class and the remaining n-2 classes, and the row vectors and column vectors composed of all the calculated elements are incorporated into the matrix L′ (n-2)×(n-2) In the equation, we get the symmetric matrix L″ (n-1)×(n-1) ;

[0024] Iterate clustering until all load nodes are clustered into one class or the distance between classes remains unchanged during adjacent iterations. The corresponding number of clusters is the optimal number of clusters. The clustering result is the partition result of the load nodes.

[0025] The impedance modulus margin of the load node is calculated using the following relationship:

[0026]

[0027] In the formula, α i is the dynamic equivalent impedance modulus margin of load node i; R iL is the static equivalent impedance of load node i; R iTHEV is the dynamic equivalent impedance of load node i; are the voltage and current at load node i respectively.

[0028] The node current coupling degree is calculated using the following relationship:

[0029]

[0030] In the formula, σ I，i is the current coupling degree of the i-th load node; represents the element in the kth row and ith column of the dynamic impedance matrix, and n is the number of nodes;

[0031] The node voltage coupling is calculated using the following relationship:

[0032]

[0033] In the formula, σ V，i Voltage coupling degree of the i-th load node; represents the i-th row and k-th column element in the dynamic impedance matrix;

[0034] The comprehensive coupling degree of each load node is calculated using the following relationship:

[0035]

[0036] In the formula, σ i is the comprehensive coupling degree of load node i.

[0037] The reactive power compensation node selection model satisfies the following relationship:

[0038]

[0039] Where H(i) is the reactive power compensation node selection model for load node i; α i is the impedance modulus margin of load node i; σ i is the comprehensive coupling degree of load node i; ρ is the weight coefficient; m is the total number of nodes in the partition where load node i is located;

[0040] In the partition, the reactive power compensation node selects the load node corresponding to the minimum value of the model as the reactive power compensation node.

[0041] Based on the least squares method, the impedance modulus margin at the reactive compensation node is fitted with the reactive compensation capacity in the partition to satisfy the following relationship:

[0042] α i =k1ΔQ1+k2ΔQ2+...+k n ΔQ n

[0043] In the formula, α i is the impedance modulus margin of load node i, load node i is the reactive power compensation node; k1, k2...k n are fitting coefficients, ΔQ1, ΔQ2, ..., ΔQ n are the reactive power compensation capacity of each load node in the partition, and n is the number of nodes;

[0044] When the minimum impedance modulus margin at the reactive power compensation node is less than the impedance modulus margin threshold, the reactive power compensation capacity configured at the reactive power compensation node in the partition is determined based on the fitting model and the impedance modulus margin threshold, satisfying the following relationship:

[0045]

[0046] In the formula, α ξ is the impedance modulus margin threshold; α min0 k is the minimum impedance modulus margin before reactive power compensation in the partition; min It is the fitting coefficient corresponding to the minimum value of impedance modulus margin after reactive power compensation in the partition.

[0047] The impedance modulus margin threshold is the critical value of the system stable state and is taken as 0.4.

[0048] The present invention also proposes a rural distribution network regulation system that takes into account load damage and node coupling, including: a collection module, a partition module, and a reactive compensation configuration module;

[0049] The acquisition module is used to collect the voltage, current, injected active power and injected reactive power of each load node in the distribution network;

[0050] A partitioning module is used to obtain the electrical distance between load nodes based on the dynamic impedance matrix, and partition the load nodes using an agglomerative hierarchical clustering method according to the electrical distance between the load nodes;

[0051] The reactive compensation configuration module is used to establish a reactive compensation node selection model in any partition according to the impedance modulus margin and the comprehensive coupling degree of the node, and determine the reactive compensation nodes in the partition according to the model; based on the least squares method, a fitting model of the reactive compensation capacity in the partition and the impedance modulus margin at the reactive compensation node is established; when the minimum value of the impedance modulus margin at the reactive compensation node is less than the impedance modulus margin threshold, the reactive compensation capacity of the reactive compensation node configuration in the partition is determined based on the fitting model with the impedance modulus margin threshold as the benchmark.

[0052] The beneficial effects of the present invention are that, compared with the prior art, at least the following are included: first, the present invention uses an agglomerative hierarchical clustering algorithm based on a dynamic impedance matrix to partition the load nodes, which can more accurately determine the load demands of different areas, thereby achieving load balancing and significantly improving power supply reliability; secondly, through a method based on impedance module margin and node comprehensive coupling degree, a reactive compensation node selection function is established to clearly define reactive compensation nodes; the key advantage of this step is to optimize power flow, reduce power loss, and improve power transmission efficiency, thereby effectively reducing the operating cost of the power system; finally, the present invention uses the least squares method to approximate the reactive compensation capacity, further improves voltage stability, reduces voltage fluctuations, improves the overall stability of the power system, and reduces the impact of voltage instability on user equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The present invention provides a flow chart of a method for regulating a rural distribution network in the electric power field taking into account load damage and node coupling. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0055] The present invention proposes a rural distribution network regulation method considering load damage and node coupling. Figure 1 As shown, the voltage, current, injected active power and injected reactive power of each load node in the distribution network are collected, including:

[0056] Step 1, obtaining the electrical distance between load nodes based on the dynamic impedance matrix, and partitioning the load nodes using an agglomerative hierarchical clustering method according to the electrical distance between the load nodes;

[0057] Specifically, it includes:

[0058] Step 1.1, take the sensitivity between the voltage change of load node i and the current change of load node j as the dynamic mutual impedance between the two nodes, take the sensitivity between the voltage change and the current change of load node i as the dynamic self-impedance of the node; use the dynamic mutual impedance and dynamic self-impedance of each node to establish the dynamic impedance matrix of the distribution network.

[0059] The traditional node coupling impedance matrix based on the local voltage stability index only considers the topological structure and power flow distribution, ignores the nonlinear dynamic characteristics of the power system, and can only approximately describe the coupling relationship between nodes. Therefore, the present invention uses a dynamic impedance matrix to describe the coupling relationship between nodes.

[0060] The ratio of the voltage change at load node i to the current change at load node j is defined as the nonlinear power system mutual impedance, which is used to describe the coupling relationship between nodes and satisfies the following relationship:

[0061]

[0062] In the formula, are the voltage change at node i and the current change at node j respectively; is the dynamic mutual impedance between nodes i and j. When i=j, it is the dynamic self-impedance.

[0063] The power system is actually a non-analytical complex function. Both the power source and the load are injected power models. Therefore, when obtaining the dynamic mutual impedance of the power system, it is necessary to introduce intermediate variables as parameter variables. Then, according to the chain rule of composite function derivation, the node voltage and current are respectively derived with respect to the parameter variables. Here, the injected power parameter λ is used as the intermediate parameter variable. Then the dynamic mutual impedance of the power system satisfies the following relationship:

[0064]

[0065] Dynamic Mutual Impedance The physical meaning of is: intuitively describing the sensitivity relationship between the voltage change of load node i and the current change of load node j. The larger the modulus value, the stronger the coupling relationship.

[0066] Therefore, the dynamic impedance matrix Satisfies the following relationship:

[0067]

[0068] In the formula, n is the number of nodes.

[0069] Step 1.2, using the ratio of the dynamic self-impedance to the dynamic mutual impedance as the projection position of the load node; using a geometric method, using the projection positions of the two nodes to calculate the electrical distance between the load nodes.

[0070] In power system calculations, the electrical distance between nodes physically represents the electrical coupling between nodes. Different calculation methods can be obtained according to different definitions of electrical distance, but the calculated electrical distances all describe the strength of the coupling relationship between nodes in a physical sense. Therefore, the electrical distance between load nodes is defined based on dynamic mutual impedance, and the electrical distance is used to accurately describe the strength of the electrical connection between nodes.

[0071] The element in the i-th row and j-th column of the dynamic impedance matrix It represents the influence of the current change of load node j on the voltage change of load node i. The element in the jth row and jth column of the dynamic impedance matrix is It represents the influence of the current of load node j on the voltage of the node itself. The ratio is As the projection position of load node i on the plane where load node j is located in n-dimensional space, the larger the ratio is, the smaller the influence of load node j current change on load node i voltage change is, and the weaker the electrical connection between node i and node j is. ij (i, j = 1, ..., n) form an n-order matrix D that satisfies the following relationship:

[0072]

[0073] The significance of matrix D is to map all load nodes into n-dimensional space. ij Represents the projection position of node i on the jth plane in the n-dimensional space. Based on geometric knowledge, the distance between two points in the space, that is, the electrical distance between load nodes, satisfies the following relationship:

[0074]

[0075] Where, d i1 ,d i2 ,……,d in are the projection positions of node i on the 1st, 2nd, ..., nth planes in the n-dimensional space; d j1 ,d j2 ,……,d jn are the projection positions of node j on the 1st, 2nd, …, nth planes in the n-dimensional space respectively.

[0076] Meet L ij =L ji , where L ij is the electrical distance between node i and node j, L ij The larger the value, the weaker the electrical connection between the two nodes and the weaker the coupling degree; L ij The smaller the value, the stronger the electrical connection between the two nodes and the stronger the coupling.

[0077] Compared with the traditional electrical distance, the electrical distance proposed in the present invention takes into account the influence of the coupling relationship between all load nodes and can more accurately reflect the strength of the coupling relationship between nodes. Therefore, the electrical distance can be used as a basis for load node partitioning.

[0078] In step 1.3, the load nodes are partitioned using agglomerative hierarchical clustering method according to the electrical distance between the load nodes.

[0079] For a power system with n load nodes, the specific steps of partitioning the load nodes based on the agglomerative hierarchical clustering method are as follows:

[0080] Step 1: Treat all load nodes as n separate classes, and calculate the electrical distances between the classes according to step 1.2 to obtain the symmetric distance matrix L = (L ij ) n×n ;

[0081] Step 2: Substitute the matrix L = (L ij ) n×n The element with the smallest non-diagonal median value min(L ij The two classes corresponding to (i≠j) are merged into one new class, and the matrix L=(L ij ) n×n The rows and columns corresponding to these two categories are obtained to obtain the symmetric distance merging matrix L′ (n-2)×(n-2) ;

[0082] Step 3: Use the minimum sum of squares method to calculate the inter-class distance between the new class and the remaining n-2 classes, and merge all the calculated elements into the matrix L′ in one row and one column. (n-2)×(n-2) In the equation, we get the symmetric matrix L″ (n-2)×(n-2) ;

[0083] Among them, the Ward distance in the minimum sum of squares method satisfies the following relationship:

[0084]

[0085] In the formula, C ij is the Ward distance between classes i and j, n i 、n j are the number of elements in class i and class j respectively, are the means of all elements in class i and class j respectively.

[0086] The significance of Ward distance is to ensure that the sum of squared deviations within each new class merged is minimized, thus ensuring the best clustering effect.

[0087] Step 4: Repeat Step 2 and 3 until all nodes are clustered into one class; or the Ward distance between classes remains unchanged during adjacent iterations, that is, when a plateau period of the inter-class merge distance appears, the corresponding number of clusters is the optimal number of clusters; the clustering result is the partitioning result.

[0088] Step 5: Make appropriate corrections and adjustments to the partition results based on actual needs.

[0089] Step 2: In any partition, a reactive compensation node selection model is established based on the impedance module margin and the node comprehensive coupling degree, and the reactive compensation nodes in the partition are determined based on the model.

[0090] After completing the partitioning of load nodes, the selection of the best reactive compensation node in each partition becomes a key issue in the reactive compensation configuration process. The present invention takes improving the voltage stability of the power system as the configuration goal, takes into account the voltage stability weak nodes and the overall compensation effect, sorts the nodes in each partition according to the voltage weakness and node robustness, combines the impedance module margin and the node comprehensive coupling degree, establishes a reactive compensation node selection function, and determines the reactive compensation node.

[0091] Specifically, it includes:

[0092] Step 2.1, calculate the dynamic equivalent impedance modulus margin of the load node using the following relationship:

[0093]

[0094] In the formula, R iL is the static equivalent impedance of load node i; R iTHEV is the dynamic equivalent impedance of load node i; α i is the dynamic equivalent impedance modulus margin of load node i, which describes the distance between the current operating state of load node i and the critical state of voltage stability, and can effectively reflect the voltage stability margin of load node i; are the voltage and current at load node i respectively.

[0095] In order to analyze the distance between the operating state of the system load node and the critical state of voltage stability, the present invention defines the dynamic equivalent impedance modulus margin as: The dynamic equivalent impedance modulus margin α of load node i i ∈[0,1], where α i When the minimum value is 0, |R iL |=|R iTHEV |, at this time, the load node operation state reaches the critical state of voltage stability; α i The larger the value, the better the voltage stability of load node i. The dynamic equivalent impedance modulus margin of each node is sorted, and the load node corresponding to the minimum value of the dynamic equivalent impedance modulus margin is taken as the weak node of voltage stability in the distribution network. The dynamic equivalent impedance modulus margin of the weak node is used to evaluate the voltage stability of the entire distribution network.

[0096] Step 2.2, the degree of influence of the current change of the load node on the voltage change of other load nodes is taken as the node current coupling degree, and the degree of influence of the voltage change of the load node by the current change of other load nodes is taken as the node voltage coupling degree; the average of the node current coupling degree and the node voltage coupling degree is taken as the node comprehensive coupling degree.

[0097] 1) Node current coupling

[0098] For the dynamic impedance matrix R d , each column element of the matrix (excluding the main diagonal elements) represents the influence of the corresponding load node current change on the voltage change of other load nodes, and the sum of the modulus values ​​of each column element (excluding the main diagonal elements) represents the overall influence of the corresponding load node current change on the voltage change of other load nodes. The proportion of the overall influence degree in the total node coupling influence is defined as the current coupling degree σ I，i :

[0099]

[0100] In the formula, Represents the element in the kth row and ith column of the dynamic impedance matrix.

[0101] σ I，i It reflects the overall impact of the current change of the i-th load node on the voltage change of other load nodes, where σ I，i ∈[0, 1],σ I，i The larger the value of the load node, the greater the overall impact of the corresponding node current change on the voltage change of other nodes.

[0102] 2) Node voltage coupling

[0103] For the dynamic impedance matrix R d , each row element of the matrix (excluding the main diagonal elements) represents the degree to which the corresponding load node voltage is affected by the change of other load node currents, and the sum of the modulus values ​​of each row element (excluding the main diagonal elements) represents the overall degree to which the corresponding load node voltage is affected by the change of other load node currents. The proportion of this overall degree of influence in the total node coupling influence is defined as the voltage coupling degree σ V，i :

[0104]

[0105] In the formula, represents the i-th row and k-th column element in the dynamic impedance matrix.

[0106] σ V，i Indicates the overall influence of the voltage change of the i-th load node on the current change of other load nodes, where σ V，i∈[0, 1],σ V，i The larger the value of the load node, the greater the overall impact of the current changes of other nodes on the corresponding node voltage change.

[0107] 3) Node comprehensive coupling degree

[0108] The comprehensive coupling degree of each load node σ is obtained by combining the current coupling degree and voltage coupling degree of each load node. i , satisfying the following relationship:

[0109]

[0110] In the formula, σ i is the comprehensive coupling degree of load node i.

[0111] σ i ∈[0, 1],σ i The larger the load node, the tighter the coupling with other load nodes in the partition, and the better the robustness in the region. By sorting the comprehensive coupling degree σ of each load node, the key nodes in the region can be determined.

[0112] Step 2.3, using the dynamic equivalent impedance modulus margin and node comprehensive coupling degree, establish a reactive compensation node selection model.

[0113] The size of the dynamic equivalent impedance modulus margin of the load node reflects the voltage stability of the node. The voltage stability of the node with the smallest impedance modulus margin determines the voltage stability level of the system. Therefore, in the selection of reactive compensation nodes, the node voltage weakness should take precedence over the node area robustness, which can be reflected by adding a weight coefficient ρ.

[0114] On the basis of load node partitioning, the voltage stability of each node can be judged according to the size of the dynamic equivalent impedance modulus margin value of each partition node. Therefore, the ratio of the dynamic equivalent impedance modulus margin value of each node in each partition to the sum of the dynamic equivalent impedance margin values ​​of all nodes in the partition can measure the proportion of voltage stability of each node in the partition.

[0115] The reactive power compensation node selection model satisfies the following relationship:

[0116]

[0117] Where H(i) is the reactive compensation node selection model for load node i, ρ is the weight coefficient, and m is the total number of nodes in the partition where load node i is located.

[0118] In the reactive power compensation node selection model, the first item In the process of selecting reactive power compensation nodes, the voltage weakness of the node is given priority; the second term ρ(1-σ i) represents the regional robustness of the node taken into account in the reactive power compensation selection process. The size of the robustness is controlled by the weight coefficient ρ.

[0119] When the focus of reactive power compensation is to improve the voltage stability of weak nodes, ρ takes a smaller value, where ρ = 0 means that only the voltage weakness of the node is considered; when the focus of reactive power compensation is to improve the voltage stability of the system as a whole, ρ takes a relatively large value, where a too large value of ρ means that only the regional robustness of the node is considered and the voltage weakness of the node is ignored, which is obviously unreasonable. Therefore, the value of ρ should not be too large.

[0120] From the previous analysis, it can be seen that the smaller the impedance modulus margin of the node in the partition, the greater the node voltage weakness; the greater the comprehensive coupling degree of the node in the partition, the greater the node regional robustness; taking both into account, the H(i) values ​​of the load nodes in the partition are sorted, and the node with the smallest H(i) value is selected as the reactive compensation node, that is, in the partition, the reactive compensation node selects the load node corresponding to the minimum value of the model as the reactive compensation node.

[0121] Step 3, based on the least squares method, establish a fitting model of the reactive compensation capacity in the partition and the impedance modulus margin at the reactive compensation node. When the minimum value of the impedance modulus margin at the reactive compensation node is less than the impedance modulus margin threshold, take the impedance modulus margin threshold as a benchmark and determine the reactive compensation capacity of the reactive compensation node configuration in the partition based on the fitting model.

[0122] The determination of reactive power compensation nodes is one of the important goals of reactive power optimization planning, and another goal is the determination of reactive power compensation capacity.

[0123] Specifically, it includes:

[0124] Step 3.1: Based on the least squares method, a fitting model of the reactive compensation capacity in the partition and the impedance modulus margin at the reactive compensation node is established.

[0125] The present invention takes improving system voltage stability as the configuration goal of reactive power compensation, and takes the minimum value of impedance modulus margin as the standard for measuring system voltage stability. The objective function is as follows:

[0126] F=α min

[0127] In the formula, α min It is the minimum value of impedance modulus margin. The larger its value is, the more stable the system voltage is.

[0128] After the reactive power compensation device is installed in the system, the voltage stability of each load node will change to a certain extent, and the impedance modulus margin will also change to a certain extent. The change of the impedance modulus margin must be related to the capacity of the reactive power compensation. Therefore, the impedance modulus margin is transformed into:

[0129]

[0130]

[0131] Where P i , Q i are the injected active power and injected reactive power of load node i respectively; P j , Q j are the injected active power and injected reactive power of load node j respectively; is the injected voltage of load node i; is the element in the i-th row and j-th column of the inverse matrix of the Jacobian matrix J; () * It means to find the conjugate.

[0132] From the above formula, we can know that |R iTHEV | is about the injected reactive power Q1, Q2...Q of each load node n The impedance modulus margin is also a function of the injected reactive power Q1, Q2...Q n The function satisfies the following relationship:

[0133] α i =f(Q1, Q2...Q n )

[0134] Therefore, based on the least squares method, the reactive power compensation capacity ΔQ1, ΔQ2, ..., ΔQ in the partition is established. n The impedance modulus margin α at the reactive compensation node i The impedance modulus margin α is obtained by fitting the model i It is about reactive power compensation capacity ΔQ1, ΔQ2, ..., ΔQ n The multivariate linear function satisfies the following relationship:

[0135] α i =k1ΔQ1+k2ΔQ2+...+k n ΔQ n

[0136] In the formula, k1, k2...k n is the fitting coefficient obtained based on the least squares method.

[0137] The accuracy of least squares fitting is greatly affected by the sampling interval and number of times. The reactive compensation capacity determined by the present invention can only preliminarily estimate the reactive compensation capacity in each partition. It must also be based on whether the system minimum impedance modulus margin reaches the threshold condition. If the minimum value of the impedance modulus margin after reactive compensation is less than the given threshold, it is necessary to update the reactive compensation capacity of the partition where the node corresponding to the minimum impedance modulus margin is located. If the minimum value of the impedance modulus margin after reactive compensation is greater than the given threshold, the reactive compensation is reasonable.

[0138] When the minimum impedance modulus margin at the reactive power compensation node is less than the impedance modulus margin threshold, the reactive power compensation capacity in the partition is determined based on the fitting model with the impedance modulus margin threshold as a benchmark.

[0139] The reactive power compensation capacity in the partition is determined with the goal of minimizing the impedance modulus margin before and after reactive power compensation. In engineering applications, the reactive power compensation capacity configured at the reactive power compensation node in the partition satisfies the following relationship:

[0140]

[0141] In the formula, α ξ is the threshold of impedance modulus margin; α min0 is the minimum impedance modulus margin before reactive compensation. According to the previous analysis, the minimum impedance modulus margin before reactive compensation corresponds to the reactive compensation node; k min is the fitting coefficient corresponding to the minimum value of the impedance modulus margin after reactive compensation in the partition, which can be obtained by fitting with the least square method. In actual engineering applications, reactive compensation capacity is only configured at reactive compensation nodes, so the reactive compensation capacity corresponding to non-reactive compensation nodes is 0. After simplification, the above formula is obtained.

[0142] The impedance modulus margin threshold is a critical value for the system to be in a stable state, and is set to 0.4 in the embodiment.

[0143] The present invention also proposes a rural distribution network regulation system that takes into account load damage and node coupling, including: a collection module, a partition module, and a reactive compensation configuration module;

[0144] The acquisition module is used to collect the voltage, current, injected active power and injected reactive power of each load node in the distribution network;

[0145] A partitioning module is used to obtain the electrical distance between load nodes based on the dynamic impedance matrix, and partition the load nodes using an agglomerative hierarchical clustering method according to the electrical distance between the load nodes;

[0146] The reactive compensation configuration module is used to establish a reactive compensation node selection model in any partition according to the impedance modulus margin and the comprehensive coupling degree of the node, and determine the reactive compensation nodes in the partition according to the model; based on the least squares method, a fitting model of the reactive compensation capacity in the partition and the impedance modulus margin at the reactive compensation node is established; when the minimum value of the impedance modulus margin at the reactive compensation node is less than the impedance modulus margin threshold, the reactive compensation capacity of the reactive compensation node configuration in the partition is determined based on the fitting model with the impedance modulus margin threshold as the benchmark.

[0147] The partition module uses the dynamic mutual impedance and dynamic self-impedance of each node to establish the dynamic impedance matrix of the distribution network, where the dynamic mutual impedance satisfies the following relationship:

[0148]

[0149] In the formula, are the voltage change at node i and the current change at node j respectively; is the dynamic mutual impedance between nodes i and j; λ is the injection power parameter; when i=j, is the dynamic self-impedance;

[0150] The ratio of dynamic self-impedance to dynamic mutual impedance As the projection position of load node i on the plane where load node j is located in n-dimensional space, is the element in the ith row and jth column of the dynamic impedance matrix, is the element in the jth row and jth column of the dynamic impedance matrix;

[0151] The partitioning module uses a geometric method to calculate the electrical distance between load nodes using the following relationship:

[0152]

[0153] Where, L ij is the electrical distance between load node i and load node j; d i1 d i2 ,……,d in are the projection positions of node i on the 1st, 2nd, ..., nth planes in the n-dimensional space; d j1 d j2 ,……,d jn are the projection positions of node j on the 1st, 2nd, ..., nth planes in the n-dimensional space respectively; n is the number of nodes;

[0154] The partitioning module partitions the load nodes according to the electrical distance between the load nodes using the agglomerative hierarchical clustering method, including:

[0155] Treat all load nodes as n separate classes, calculate the electrical distances between the classes, and obtain the symmetric distance matrix L = (Lij ) n×n ;

[0156] The matrix L = (L ij ) n×n The element with the smallest non-diagonal median value min(L ij )(i≠j) are merged into a new class, and the matrix L=(L ij ) n×n The rows and columns corresponding to the two classes in the symmetric distance merge matrix L′ (n-2)×(n-2) ;

[0157] The minimum sum of squares of deviations method is used to calculate the inter-class distance between the new class and the remaining n-2 classes, and the row vectors and column vectors composed of all the calculated elements are incorporated into the matrix L′ (n-2)×(n-2) In the equation, we get the symmetric matrix L″ (n-1)×(n-1) ;

[0158] Iterate clustering until all load nodes are clustered into one class or the distance between classes remains unchanged during adjacent iterations. The corresponding number of clusters is the optimal number of clusters. The clustering result is the partition result of the load nodes.

[0159] The reactive power compensation configuration module calculates the impedance modulus margin of the load node using the following relationship:

[0160]

[0161] In the formula, α i is the dynamic equivalent impedance modulus margin of load node i; R iL is the static equivalent impedance of load node i; R iTHEV is the dynamic equivalent impedance of load node i; are the voltage and current of load node i respectively;

[0162] The reactive power compensation configuration module calculates the node current coupling degree according to the following relationship:

[0163]

[0164] In the formula, σ I，i is the current coupling degree of the i-th load node; represents the element in the kth row and ith column of the dynamic impedance matrix, and n is the number of nodes;

[0165] The reactive power compensation configuration module calculates the node voltage coupling degree according to the following relationship:

[0166]

[0167] In the formula, σ V，i Voltage coupling degree of the i-th load node; represents the i-th row and k-th column element in the dynamic impedance matrix;

[0168] The reactive power compensation configuration module calculates the comprehensive coupling degree of each load node using the following relationship:

[0169]

[0170] In the formula, σ i is the comprehensive coupling degree of load node i;

[0171] The reactive compensation node selection model established by the reactive compensation configuration module satisfies the following relationship:

[0172]

[0173] Where H(i) is the reactive power compensation node selection model for load node i; α i is the impedance modulus margin of load node i; σ i is the comprehensive coupling degree of load node i; ρ is the weight coefficient; m is the total number of nodes in the partition where load node i is located;

[0174] In the partition, the reactive power compensation node selects the load node corresponding to the minimum value of the model as the reactive power compensation node.

[0175] The reactive compensation configuration module, based on the least squares method, fits the impedance modulus margin at the reactive compensation node with the reactive compensation capacity in the partition to satisfy the following relationship:

[0176] α i =k1ΔQ1+k2ΔQ2+...+k m ΔQ n

[0177] In the formula, α i is the impedance modulus margin of load node i, load node i is the reactive power compensation node; k1, k2...k n are fitting coefficients, ΔQ1, ΔQ2, ..., ΔQ n are the reactive power compensation capacity of each load node in the partition, and n is the number of nodes;

[0178] When the minimum impedance modulus margin at the reactive power compensation node is less than the impedance modulus margin threshold, the reactive power compensation capacity configured at the reactive power compensation node in the partition is determined based on the fitting model and the impedance modulus margin threshold, satisfying the following relationship:

[0179]

[0180] In the formula, α ξ is the impedance modulus margin threshold; α min0 k is the minimum impedance modulus margin before reactive power compensation in the partition;min It is the fitting coefficient corresponding to the minimum value of impedance modulus margin after reactive power compensation in the partition.

[0181] The impedance modulus margin threshold is the critical value of the system stable state and is taken as 0.4.

[0182] In summary, the regulation method of the present invention has significant innovation and practicality in the field of rural power distribution networks. It can improve power supply reliability, reduce power loss, and improve voltage stability, bringing multiple beneficial effects to the performance and reliability of the power system, and is of great significance for improving rural power supply and reducing operating costs.

[0183] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0184] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0185] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0186] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0187] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A rural distribution network regulation method considering load damage and node coupling, characterized in that: include: Collect the voltage, current, injected active power and injected reactive power of each load node in the distribution network; According to the voltage and current, the electrical distance between the load nodes is obtained based on the dynamic impedance matrix. According to the electrical distance between the load nodes, the load nodes are partitioned using the agglomerative hierarchical clustering method. In any zone, a reactive compensation node selection model is established based on the impedance modulus margin and the node comprehensive coupling degree, and the reactive compensation nodes in the zone are determined based on the model; According to the injected active power and injected reactive power, based on the least squares method, a fitting model of the reactive compensation capacity in the partition and the impedance modulus margin at the reactive compensation node is established. When the minimum value of the impedance modulus margin at the reactive compensation node is less than the impedance modulus margin threshold, the reactive compensation capacity of the reactive compensation node configuration in the partition is determined based on the fitting model with the impedance modulus margin threshold as the benchmark.

2. The rural distribution network regulation method considering load damage and node coupling according to claim 1 is characterized in that: The dynamic mutual impedance satisfies the following relationship: In the formula, are the voltage change at node i and the current change at node j respectively; is the dynamic mutual impedance between node i and node j; λ is the injection power parameter; When i=j, it is dynamic self-impedance; The dynamic impedance matrix of the distribution network is established using the dynamic mutual impedance and dynamic self-impedance of each node.

3. The rural distribution network regulation method considering load damage and node coupling according to claim 2 is characterized in that: The ratio of dynamic self-impedance to dynamic mutual impedance As the projection position of load node i on the plane where load node j is located in n-dimensional space, is the element in the ith row and jth column of the dynamic impedance matrix, is the element in the jth row and jth column of the dynamic impedance matrix; Using the geometric method, the electrical distance between load nodes is calculated using the following relationship: Where, L ij is the electrical distance between load node i and load node j; d i1 d i2 ,……,d in are the projection positions of node i on the 1st, 2nd, ..., nth planes in the n-dimensional space; d j1 d j2 ,……,d jn are the projection positions of node j on the 1st, 2nd, …, nth planes in the n-dimensional space respectively; n is the number of nodes.

4. The rural distribution network regulation method considering load damage and node coupling according to claim 3 is characterized in that: According to the electrical distance between load nodes, the load nodes are partitioned using the agglomerative hierarchical clustering method, including: Treat all load nodes as n separate classes, calculate the electrical distances between the classes, and obtain the symmetric distance matrix L = (L ij ) n×n ; The matrix L = (L ij ) n×n The element with the smallest non-diagonal median value min(L ij )(i≠j) are merged into a new class, and the matrix L=(L ij ) n×n The rows and columns corresponding to the two classes in the , and the symmetric distance merge matrix L ′ is obtained (n-2)×(n-2) ; The minimum sum of squares of deviations method is used to calculate the inter-class distance between the new class and the remaining n-2 classes, and the row vectors and column vectors composed of all the calculated elements are incorporated into the matrix L′ (n-2)×(n-2) In the equation, we get the symmetric matrix L″ (n-1)×(n-1) ; Iterate clustering until all load nodes are clustered into one class or the distance between classes remains unchanged during adjacent iterations. The corresponding number of clusters is the optimal number of clusters. The clustering result is the partition result of the load nodes.

5. The rural distribution network regulation method considering load damage and node coupling according to claim 2, characterized in that: The impedance modulus margin of the load node is calculated using the following relationship: In the formula, α i is the dynamic equivalent impedance modulus margin of load node i; R iL is the static equivalent impedance of load node i; R iTHEV is the dynamic equivalent impedance of load node i; are the voltage and current at load node i respectively.

6. The rural distribution network regulation method considering load damage and node coupling according to claim 2, characterized in that: The node current coupling degree is calculated using the following relationship: In the formula, σ I，i is the current coupling degree of the i-th load node; represents the element in the kth row and ith column of the dynamic impedance matrix, and n is the number of nodes; The node voltage coupling is calculated using the following relationship: In the formula, σ Vti Voltage coupling degree of the i-th load node; represents the i-th row and k-th column element in the dynamic impedance matrix; The comprehensive coupling degree of each load node is calculated using the following relationship: In the formula, σ i is the comprehensive coupling degree of load node i.

7. The rural distribution network regulation method considering load damage and node coupling according to claim 1, characterized in that: The reactive power compensation node selection model satisfies the following relationship: Where H(i) is the reactive power compensation node selection model for load node i; α i is the impedance modulus margin of load node i; σ i is the comprehensive coupling degree of load node i; ρ is the weight coefficient; m is the total number of nodes in the partition where load node i is located; In the partition, the reactive power compensation node selects the load node corresponding to the minimum value of the model as the reactive power compensation node.

8. The rural distribution network regulation method considering load damage and node coupling according to claim 1, characterized in that: Based on the least squares method, the impedance modulus margin at the reactive compensation node is fitted with the reactive compensation capacity in the partition to meet the following relationship: α i =k t ΔQ t +k2ΔQ2+...+k n ΔQ n In the formula, α i is the impedance modulus margin of load node i, load node i is the reactive power compensation node; k t , k2...k n are fitting coefficients, ΔQ1, ΔQ2, ..., ΔQ n are the reactive power compensation capacity of each load node in the partition, and n is the number of nodes; When the minimum impedance modulus margin at the reactive power compensation node is less than the impedance modulus margin threshold, the reactive power compensation capacity configured at the reactive power compensation node in the partition is determined based on the fitting model and the impedance modulus margin threshold, satisfying the following relationship: In the formula, α ξ is the impedance modulus margin threshold; α min0 k is the minimum impedance modulus margin before reactive power compensation in the partition; min It is the fitting coefficient corresponding to the minimum value of impedance modulus margin after reactive power compensation in the partition.

9. The rural distribution network regulation method considering load damage and node coupling according to claim 8, characterized in that: The impedance modulus margin threshold is the critical value of the system stable state and is taken as 0.

4.

10. A rural distribution network regulation system considering load damage and node coupling, characterized in that: include: Acquisition module, partition module, reactive power compensation configuration module; The acquisition module is used to collect the voltage, current, injected active power and injected reactive power of each load node in the distribution network; A partitioning module is used to obtain the electrical distance between load nodes based on the voltage and current and the dynamic impedance matrix, and partition the load nodes using an agglomerative hierarchical clustering method according to the electrical distance between the load nodes; The reactive compensation configuration module is used to establish a reactive compensation node selection model in any partition according to the impedance modulus margin and the node comprehensive coupling degree, and determine the reactive compensation nodes in the partition according to the model; According to the injected active power and injected reactive power, based on the least squares method, a fitting model of the reactive compensation capacity in the partition and the impedance modulus margin at the reactive compensation node is established. When the minimum value of the impedance modulus margin at the reactive compensation node is less than the impedance modulus margin threshold, the reactive compensation capacity of the reactive compensation node configuration in the partition is determined based on the fitting model with the impedance modulus margin threshold as the benchmark.

11. The rural distribution network regulation system considering load damage and node coupling according to claim 10, characterized in that: The partition module uses the dynamic mutual impedance and dynamic self-impedance of each node to establish the dynamic impedance matrix of the distribution network, where the dynamic mutual impedance satisfies the following relationship: In the formula, are the voltage change at node i and the current change at node j respectively; is the dynamic mutual impedance between nodes i and j; λ is the injection power parameter; when i=j, is the dynamic self-impedance; The ratio of dynamic self-impedance to dynamic mutual impedance As the projection position of load node i on the plane where load node j is located in n-dimensional space, is the element in the ith row and jth column of the dynamic impedance matrix, is the element in the jth row and jth column of the dynamic impedance matrix; The partitioning module uses a geometric method to calculate the electrical distance between load nodes using the following relationship: Where, L ij is the electrical distance between load node i and load node j; d i1 d i2 ,……,d in are the projection positions of node i on the 1st, 2nd, ..., nth planes in the n-dimensional space; d j1 d j2 ,……,d jn are the projection positions of node j on the 1st, 2nd, ..., nth planes in the n-dimensional space respectively; n is the number of nodes; The partitioning module partitions the load nodes according to the electrical distance between the load nodes using the agglomerative hierarchical clustering method, including: Treat all load nodes as n separate classes, calculate the electrical distances between the classes, and obtain the symmetric distance matrix L = (L ij ) n×n ; The matrix L = (L ij ) n×n The element with the smallest non-diagonal median value min(L ij )(i≠j) are merged into a new class, and the matrix L=(L ij ) n×n The rows and columns corresponding to the two classes in the , and the symmetric distance merge matrix L ′ is obtained (n-2)×(n-2) ; The minimum sum of squares of deviations method is used to calculate the inter-class distance between the new class and the remaining n-2 classes, and the row vectors and column vectors composed of all the calculated elements are incorporated into the matrix L′ (n-2)×(n-2) In the equation, we get the symmetric matrix L″ (n-1)×(n-1) ; Iterate clustering until all load nodes are clustered into one class or the distance between classes remains unchanged during adjacent iterations. The corresponding number of clusters is the optimal number of clusters. The clustering result is the partition result of the load nodes.

12. The rural distribution network regulation system considering load damage and node coupling according to claim 10, characterized in that: The reactive power compensation configuration module calculates the impedance modulus margin of the load node using the following relationship: In the formula, α i is the dynamic equivalent impedance modulus margin of load node i; R iL is the static equivalent impedance of load node i; R iTHEV is the dynamic equivalent impedance of load node i; are the voltage and current of load node i respectively; The reactive power compensation configuration module calculates the node current coupling degree according to the following relationship: In the formula, σ I，i is the current coupling degree of the i-th load node; represents the element in the kth row and ith column of the dynamic impedance matrix, and n is the number of nodes; The reactive power compensation configuration module calculates the node voltage coupling degree according to the following relationship: In the formula, σ V，i Voltage coupling degree of the i-th load node; represents the i-th row and k-th column element in the dynamic impedance matrix; The reactive power compensation configuration module calculates the comprehensive coupling degree of each load node using the following relationship: In the formula, σ i is the comprehensive coupling degree of load node i; The reactive compensation node selection model established by the reactive compensation configuration module satisfies the following relationship: Where H(i) is the reactive power compensation node selection model for load node i; α i is the impedance modulus margin of load node i; σ i is the comprehensive coupling degree of load node i; ρ is the weight coefficient; m is the total number of nodes in the partition where load node i is located; In the partition, the reactive power compensation node selects the load node corresponding to the minimum value of the model as the reactive power compensation node.

13. The rural distribution network regulation system considering load damage and node coupling according to claim 10, characterized in that: The reactive compensation configuration module, based on the least squares method, fits the impedance modulus margin at the reactive compensation node with the reactive compensation capacity in the partition to satisfy the following relationship: α i =k t ΔQ t +k2ΔQ2+...+k n ΔQ n In the formula, α i is the impedance modulus margin of load node i, load node i is the reactive power compensation node; k t , k2...k n are fitting coefficients, ΔQ1, ΔQ2, ..., ΔQ n are the reactive power compensation capacity of each load node in the partition, and n is the number of nodes; When the minimum impedance modulus margin at the reactive power compensation node is less than the impedance modulus margin threshold, the reactive power compensation capacity configured at the reactive power compensation node in the partition is determined based on the fitting model and the impedance modulus margin threshold, satisfying the following relationship: In the formula, α ξ is the impedance modulus margin threshold; α min0 k is the minimum impedance modulus margin before reactive power compensation in the partition; min It is the fitting coefficient corresponding to the minimum value of impedance modulus margin after reactive power compensation in the partition.

14. The rural distribution network regulation system considering load damage and node coupling according to claim 13, characterized in that: The impedance modulus margin threshold is the critical value of the system stable state and is taken as 0.

4.

15. A terminal comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to execute the steps of the method according to any one of claims 1 to 9.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

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