Loss reduction method, medium and system for regional distribution network of new energy based on reactive power optimization

Abstract

The present invention discloses a method, medium and system for reducing loss of a new energy regional distribution network based on reactive power optimization, including: establishing a simplified distribution network model according to the obtained distribution network topology structure; determining the reactive power adjustable interval of each reactive power adjustable point in the distribution network model; solving the objective function of the reactive power adjustable point under the constraint of the reactive power adjustable interval to obtain the reactive power control target quantity of the reactive power adjustable point. The present invention fully mobilizes the reactive power regulation resources of the new energy regional distribution network, promotes the reactive power balance of the distribution network on the premise of ensuring the safety and stability of the distribution network, and achieves the effect of reducing the redundant reactive power flow of the distribution network, thereby achieving the goal of reducing the loss of the distribution network and improving the active power transmission capacity of the distribution network, and improving the economy of the operation of the distribution network.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network loss reduction, and in particular to a new energy regional distribution network loss reduction method, medium and system based on reactive power optimization. Background Art

[0002] With the rapid development of distributed new energy in distribution networks, the distribution network trends have undergone tremendous changes, and new reactive power regulation resources and means have also emerged. The reactive power control of power grids mainly follows the principle of local balance, but due to the limited and uneven distribution of reactive power regulation resources in traditional distribution networks, there are still a large number of redundant reactive power flows in the power grid. These redundant reactive power flows not only cause power grid losses, but also occupy the active power transmission capacity of the power grid, reducing the operating efficiency of the power grid. In recent years, the number of distributed new energy grid-connected has continued to increase. On the one hand, the inverters of new energy stations have the ability to generate reactive power. On the other hand, in order to ensure voltage safety, some new energy plants will add reactive power regulation equipment such as SVG, providing new reactive power sources for the distribution network. At the same time, since the distributed new energy stations in the distribution network are closer to the load, they can better meet the reactive power control principle of local balance. However, the reactive power resources of the new energy regional distribution network in the prior art are not fully utilized, and the redundant reactive power flows cause power loss and occupy the active power transmission capacity of the power grid. Summary of the invention

[0003] The embodiments of the present invention provide a method, medium and system for reducing losses in a new energy regional distribution network based on reactive power optimization, so as to solve the problems of insufficient reactive power resource utilization in the new energy regional distribution network in the prior art, power loss caused by redundant reactive power flow and occupation of active power transmission capacity of the power grid.

[0004] In a first aspect, a method for reducing losses in a new energy regional distribution network based on reactive power optimization is provided, comprising:

[0005] A simplified distribution network model is established according to the obtained distribution network topology structure;

[0006] Determine the reactive power adjustable range of each reactive power adjustable point in the distribution network model;

[0007] Under the constraint of the reactive power adjustable interval, the objective function of the reactive power adjustable point is solved to obtain the reactive power control target value of the reactive power adjustable point.

[0008] In a second aspect, a computer-readable storage medium is provided, on which computer program instructions are stored; when the computer program instructions are executed by a processor, the method for reducing losses in a new energy regional distribution network based on reactive power optimization as described in the embodiment of the first aspect above is implemented.

[0009] In a third aspect, a new energy regional distribution network loss reduction system based on reactive power optimization is provided, comprising: a computer-readable storage medium as described in the above-mentioned second aspect embodiment.

[0010] In this way, the embodiments of the present invention fully mobilize the reactive power regulation resources of the new energy regional distribution network, promote the on-site reactive power balance of the distribution network while ensuring the safety and stability of the distribution network, and achieve the effect of reducing the redundant reactive power flow of the distribution network, thereby achieving the goal of reducing the loss of the distribution network, improving the active power transmission capacity of the distribution network, and improving the economy of the distribution network operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0012] Figure 1 It is a flow chart of a method for reducing losses in a new energy regional distribution network based on reactive power optimization according to an embodiment of the present invention;

[0013] Figure 2 is a schematic diagram of a distribution network topology structure according to a specific embodiment of the present invention;

[0014] Figure 3 It is a schematic diagram of the range of the reactive power adjustable interval according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] The embodiment of the present invention discloses a method for reducing losses in a new energy regional distribution network based on reactive power optimization. Figure 1 As shown, the method comprises the following steps:

[0017] Step S1: Establish a simplified distribution network model according to the acquired distribution network topology.

[0018] Specifically, this step includes the following process:

[0019] (1) Determine whether the load nodes in the distribution network topology have reactive power regulation capabilities.

[0020] (2) If at least two sequentially connected load nodes do not have reactive power regulation capability, and one of the load nodes is an end node, the at least two sequentially connected load nodes are merged into a root node of the at least two sequentially connected load nodes to establish a simplified distribution network model.

[0021] The distribution network generally has a tree structure. Multiple pure load nodes at the end that do not have reactive power regulation capabilities can be integrated into one load node because they cannot optimize reactive power flow, thereby reducing model nodes and simplifying calculations.

[0022] The root node described in the embodiment of the present invention refers to the top-level node of at least two load nodes that can be merged in sequence. The active load and reactive load of the merged root node are respectively the sum of the active load and reactive load of all load nodes merged into the root node.

[0023] like Figure 2 As shown in the figure, nodes 1 to 3 have reactive power regulation capability, node 2 has power access, and nodes 4 to 7 do not have reactive power regulation capability. Node 4 is the terminal node, but node 3 connected to node 4 has reactive power regulation capability, so the two cannot be merged. Node 7 is the terminal node, and nodes 6 and 5 connected to node 7 in sequence do not have reactive power regulation capability either. Therefore, nodes 5 to 7 can be merged, and nodes 6 and 7 are merged into node 5. The active load and reactive load of node 5 after the merger are respectively the sum of the active load and reactive load of nodes 5 to 7 before the merger.

[0024] Step S2: Determine the reactive power adjustable range of each reactive power adjustable point in the distribution network model.

[0025] For example, renewable energy and substation nodes are reactive power adjustable points in the distribution network model. Reactive power adjustable points are generally equipped with capacitors, and some renewable energy area reactive power adjustable points are equipped with continuously adjustable dynamic reactive power compensation equipment.

[0026] Specifically, if node i in the distribution network model is a reactive power adjustable point, the reactive power adjustable range of node i includes the following two types:

[0027] (1) When node i satisfies Q si ≤2Q di When the first reactive power adjustable interval of node i is [-Q di ,mQ si +Q di ], at this time, node i is a continuously adjustable point.

[0028] (2) When node i satisfies Q si >2Q di When the second reactive power adjustable interval of node i is [nQ si -Q di,nQ si +Q di ], n = 0, 1, ..., m, at this time, node i is a discontinuously adjustable point.

[0029] Among them, Q di Indicates the maximum value of the dynamic reactive power capacity configured at node i. The action range of the dynamic reactive power compensation device configured at node i can be within [-Q di ,Q di ] changes, Q si represents the reactive capacity of each group of capacitors configured at node i, and m represents the number of capacitors configured at node i.

[0030] Figure 3 The reactive power adjustable range of the continuous adjustable point and the discontinuous adjustable point when m=2 is shown. Figure 2 The dark-medium area is the adjustable range of reactive power.

[0031] Step S3: Under the constraint of the reactive power adjustable range, solve the objective function of the reactive power adjustable point to obtain the reactive power control target value of the reactive power adjustable point.

[0032] Specifically, this step includes the following process:

[0033] (1) Establish the objective function of optimal power flow calculation.

[0034] Specifically, the objective function of the optimal power flow calculation is as follows:

[0035]

[0036] Among them, P loss represents the total active power loss, branch represents the set of power grid branches, G ij represents the conductance of node i, j in a branch, U i and U j Represent the voltage of nodes i and j of a branch, δ ij The branch described in the embodiment of the present invention refers to a line composed of any two connected nodes, for example, nodes 1 and 2 form a branch, and nodes 2 and 3 also form a branch.

[0037] (2) Under the constraints of the optimal power flow (OPF) calculation of each node in the distribution network model, the objective function of the optimal power flow calculation is solved to obtain the reactive power under the optimal power flow of each node in the distribution network model.

[0038] Specifically, depending on the type of the node, the constraint conditions for the optimal power flow calculation of the node are different.

[0039] For non-reactive adjustable points, the constraints of the optimal power flow calculation include: optimal power flow node power balance constraints, and node voltage constraints.

[0040] For reactive power adjustable points, if there are non-continuous adjustable points in the power grid model, the power flow calculation constraints will be too complicated. Therefore, when solving the objective function of the optimal power flow calculation for the first time, all nodes are regarded as continuously adjustable points.

[0041] Based on this, for the reactive power adjustable point, the optimal power flow calculation constraint conditions adopted in the initial solution of the objective function of the optimal power flow calculation include: the first reactive power adjustable interval of the node, the optimal power flow node power balance constraint, and the node voltage constraint.

[0042] Specifically, the method for solving the objective function of the optimal power flow calculation may be the Newton-Raphson method. It should be understood that the real-time operating parameters used in the calculation can all be obtained through collection.

[0043] Specifically, the optimal power flow node power balance constraints include:

[0044]

[0045]

[0046] Among them, P opfi and Q opfi They represent the active power and reactive power of node i under the optimal power flow, P G,i and P L,i They represent the active generation power and active load power of node i, respectively, Q G,i and Q L,i They represent the reactive power generation and reactive load power of node i, Q C,i represents the current reactive power compensation amount of node i, B ij Represents the electrical susceptance of the branch composed of nodes i and j.

[0047] Specifically, the node voltage constraints include:

[0048] U imin ≤U i ≤U imax and U jmin ≤U j ≤U jmax ;

[0049] Among them, U imin and U imax They represent the lower and upper limits of the voltage at node i of a branch, U jmin and U jmax They represent the lower and upper limits of the voltage at node j of a branch respectively.

[0050] (3) For each reactive power adjustable point, the reactive power under the optimal power flow of the reactive power adjustable point is used to solve the objective function of the reactive power adjustable point, and the reactive power adjustable amount of the reactive power adjustable point is obtained.

[0051] For each reactive power adjustable point, it is hoped that the redundant reactive power of the reactive power adjustable point can be minimized by adjusting the reactive power control target quantity, with Q li represents the redundant reactive power of node i, i.e., Q li = 0. Redundant reactive power Q of node i li The calculation formula is as follows:

[0052] Q li =Q opfi -Q i , i=1,2,…,k.

[0053] Among them, Q opfi represents the reactive power under the optimal power flow of node i, Q i represents the reactive power output value of node i at the current moment, and k represents the number of adjustable reactive power nodes. When the redundant reactive power is the smallest, that is, Q li =0, then Q i =Q opfi , indicating that the reactive power of node i is optimal. At this time, the node is running under the optimal power flow and no reactive power optimization is required. Otherwise, it means that there is still room for optimization of the reactive power of the node, that is, it is necessary to determine the reactive power control target to minimize the redundant reactive power.

[0054] Based on the above reasons, the objective function for establishing the reactive power adjustable point is:

[0055] Q C,ti =Q opfi -(Q G,i -Q L,i ).

[0056] Among them, Q C,ti represents the reactive power adjustable quantity of node i, Q opfi , Q G,i and Q L,i As mentioned before.

[0057] (4) If the reactive adjustable quantities of all discontinuous adjustable points among the reactive adjustable points initially solved are all within the second reactive adjustable interval, the reactive adjustable quantities of all the reactive adjustable points are determined as their respective reactive control target quantities.

[0058] That is, if node i is a discontinuously adjustable point, and the Q of all discontinuously adjustable points is C,ti Located at the node corresponding to [nQ si -Q di ,nQsi +Q di ], the reactive adjustable amount of all reactive adjustable points is determined as the reactive control target amount Q C,ti .

[0059] In addition, due to the existence of discontinuously adjustable points, it may not be possible to fall into the reactive adjustable interval of the discontinuously adjustable points. If the most recent reactive amount is directly used for adjustment, the voltage may exceed the limit. Therefore, step S3 also includes the following process:

[0060] (5) If the reactive adjustable value of at least one discontinuously adjustable point among the reactive adjustable points initially calculated is outside the second reactive adjustable interval, the steps of solving the objective function of the optimal power flow calculation and solving the objective function of the reactive adjustable points are performed again.

[0061] That is, if node i is a discontinuously adjustable point, and the Q of at least one discontinuously adjustable point C,ti Located at the node corresponding to [nQ si -Q di ,nQ si +Q di ], then step (2) needs to be repeated for each node, and step (3) needs to be repeated using the result obtained after repeating step (2).

[0062] Among them, for the reactive power adjustable point, the constraints of the optimal power flow calculation adopted in resolving the objective function of the optimal power flow calculation include: the reactive power adjustable interval re-determined according to the reactive power adjustable amount of the reactive power adjustable point obtained by the initial solution, the optimal power flow node power balance constraint, and the node voltage constraint.

[0063] Specifically, according to the reactive adjustable quantity Q of the reactive adjustable point obtained by the initial solution, C,ti The re-determined reactive power adjustable range includes the following two situations:

[0064] (a) For a reactive adjustable point, if the reactive adjustable amount initially solved is located within a second reactive adjustable interval of the reactive adjustable point, the re-determined reactive adjustable interval is the second reactive adjustable interval in which the reactive adjustable amount is located.

[0065] (b) For a reactive adjustable point, if the reactive adjustable amount initially solved is not within any second reactive adjustable interval of the reactive adjustable point, the re-determined reactive adjustable interval is the second reactive adjustable interval closest to the reactive adjustable amount.

[0066] In addition, for the reactive adjustable point, if the number of the second reactive adjustable intervals closest to the reactive adjustable amount is two, that is, the reactive adjustable amount is equidistant from its two adjacent intervals A and B, and is located exactly in the middle of the two intervals A and B, in this case, two reactive adjustable intervals can be regenerated, one reactive adjustable interval is interval A, and the other reactive adjustable interval is interval B. In this way, in step (2) of resolving the objective function of the optimal power flow calculation, the two second reactive adjustable intervals are respectively used as the reactive adjustable intervals of the reactive adjustable point for calculation. Therefore, for the node, two minimum total active power losses are obtained, and the reactive power under the optimal power flow corresponding to the obtained minimum total active power loss is used to solve the objective function of the reactive adjustable point in step (3).

[0067] It should be understood that, for non-reactive adjustable points, the constraints remain unchanged.

[0068] (6) The reactive adjustable quantity of each reactive adjustable point obtained by resolving the objective function of the reactive adjustable point is determined as the reactive control target quantity of each reactive adjustable point.

[0069] Through the above method, the reactive power control target value of each reactive power adjustable point can be determined, so that the reactive power control target value can be used to control the node, thereby achieving the effect of reducing redundant reactive power flow in the distribution network, thereby achieving the goal of reducing network losses and improving grid operation efficiency.

[0070] An embodiment of the present invention also discloses a computer-readable storage medium, on which computer program instructions are stored; when the computer program instructions are executed by a processor, the loss reduction method for a new energy regional distribution network based on reactive power optimization as described in the above embodiment is implemented.

[0071] An embodiment of the present invention further discloses a new energy regional distribution network loss reduction system based on reactive power optimization, comprising: a computer-readable storage medium as described in the above embodiment.

[0072] In summary, the embodiments of the present invention fully mobilize the reactive regulation resources of the new energy regional distribution network through optimized modeling of the new energy regional distribution network, calculation of the reactive adjustable interval, redundant reactive calculation based on the optimal power flow, and optimization of the reactive control target. Under the premise of ensuring the safety and stability of the distribution network, the reactive power of the distribution network is promoted on-site, and the effect of reducing the redundant reactive power flow of the distribution network is achieved, thereby achieving the goal of reducing the loss of the distribution network, improving the active power transmission capacity of the distribution network, and improving the economy of the distribution network operation.

[0073] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for reducing losses in a new energy regional distribution network based on reactive power optimization, characterized in that: include: A simplified distribution network model is established according to the obtained distribution network topology structure; Determine the reactive power adjustable range of each reactive power adjustable point in the distribution network model; Under the constraint of the reactive power adjustable range, solving the objective function of the reactive power adjustable point to obtain the reactive power control target value of the reactive power adjustable point; If the nodes in the distribution network model i is the reactive power adjustable point, then when the node i satisfy When the node i The first reactive power adjustable range is ,node i is a continuously adjustable point; when the node i satisfy When the node i The second reactive power adjustable range is , n =0, 1, ..., m ,node i It is a non-continuous adjustable point; in, Representation Node i The maximum value of the configured dynamic reactive capacity, Representation Node i The reactive capacity of each group of capacitors configured, m Representation Node i The number of capacitors configured; The step of solving the objective function of the reactive power adjustable point comprises: Establish the objective function of optimal power flow calculation; Under the constraint conditions of the optimal power flow calculation of each node in the distribution network model, solving the objective function of the optimal power flow calculation to obtain the reactive power under the optimal power flow of each node in the distribution network model; For each reactive power adjustable point, the reactive power under the optimal power flow of the reactive power adjustable point is used to solve the objective function of the reactive power adjustable point, and the reactive power adjustable amount of the reactive power adjustable point is obtained; If the reactive adjustable quantities of all discontinuously adjustable points among the reactive adjustable points obtained by the initial solution are within the second reactive adjustable interval, then determining the reactive adjustable quantities of all the reactive adjustable points as their respective reactive control target quantities; Among them, for the reactive power adjustable point, the optimal power flow calculation constraint conditions adopted by the objective function of the initial solution of the optimal power flow calculation include: the first reactive power adjustable interval of the node, the optimal power flow node power balance constraint, and the node voltage constraint; For non-reactive adjustable points, the constraints of the optimal power flow calculation include: optimal power flow node power balance constraints, and node voltage constraints; The objective function of the reactive power adjustable point is: , Representation Node i The reactive power adjustable quantity, Representation Node i The reactive power under the optimal power flow is Representation Node i The reactive power generation Representation Node i Reactive load power; The objective function of the optimal power flow calculation is: ； in, represents the total active power loss, branch represents the set of power grid branches, A node representing a branch i , j The conductivity, U i and U j Represents the nodes of a branch respectively i and j The voltage, A node representing a branch i and j The phase angle difference; The optimal power flow node power balance constraint includes: ； ； in, and They represent the nodes under the optimal power flow i The active power and reactive power of and Respectively represent nodes i The active power generation and active load power, Representation Node i The current reactive power compensation amount, Representation Node i , j Susceptance of the branch circuits formed; The node voltage constraints include: and ; in, and Represents the nodes of a branch respectively i The voltage lower and upper limits, and Represents the nodes of a branch respectively j The lower and upper voltage limits.

2. The method according to claim 1, characterized in that: The step of establishing a simplified distribution network model according to the acquired distribution network topology structure comprises: Determine whether the load nodes in the distribution network topology have reactive power regulation capabilities; If at least two sequentially connected load nodes do not have reactive power regulation capability, and one of the load nodes is an end node, the at least two sequentially connected load nodes are merged into a root node of the at least two sequentially connected load nodes to establish a simplified distribution network model.

3. The method according to claim 1, characterized in that The step of solving the objective function of the reactive power adjustable point also includes: If the reactive adjustable amount of at least one discontinuously adjustable point among the reactive adjustable points obtained by the initial calculation is outside the second reactive adjustable interval, the steps of solving the objective function of the optimal power flow calculation and solving the objective function of the reactive adjustable points are repeated; The reactive adjustable amount of each reactive adjustable point obtained by resolving the objective function of the reactive adjustable point is determined as the reactive control target amount of each reactive adjustable point; Among them, for the reactive power adjustable point, the constraints of the optimal power flow calculation adopted in resolving the objective function of the optimal power flow calculation include: the reactive power adjustable interval re-determined according to the reactive power adjustable amount of the reactive power adjustable point obtained by the initial solution, the optimal power flow node power balance constraint, and the node voltage constraint.

4. The method according to claim 3, characterized in that: The reactive adjustable range re-determined according to the reactive adjustable amount of the reactive adjustable point obtained by the initial solution includes: For the reactive adjustable point, if the reactive adjustable amount obtained by the initial solution is located in a second reactive adjustable interval of the reactive adjustable point, the re-determined reactive adjustable interval is a second reactive adjustable interval in which the reactive adjustable amount is located; For the reactive adjustable point, if the reactive adjustable amount initially solved is not within any second reactive adjustable interval of the reactive adjustable point, the re-determined reactive adjustable interval is the second reactive adjustable interval closest to the reactive adjustable amount.

5. The method according to claim 4, characterized in that: For the reactive adjustable point, if the number of the second reactive adjustable intervals closest to the reactive adjustable amount is two, then in the step of re-solving the objective function of the optimal power flow calculation, the two second reactive adjustable intervals are respectively used as the reactive adjustable intervals of the reactive adjustable point for calculation, and the reactive power under the optimal power flow corresponding to the obtained minimum total active power loss is used to solve the objective function of the reactive adjustable point.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions; when the computer program instructions are executed by the processor, the loss reduction method for a new energy regional distribution network based on reactive power optimization as described in any one of claims 1 to 5 is implemented.

7. A new energy regional distribution network loss reduction system based on reactive power optimization, characterized in that: include: The computer readable storage medium of claim 6.

Images