CN-121663661-B - Distribution network photovoltaic bearing capacity optimization method and system based on impedance weight

CN121663661BCN 121663661 BCN121663661 BCN 121663661BCN-121663661-B

Abstract

The invention provides a distribution network photovoltaic bearing capacity optimization method and system based on impedance weights, the method comprises the steps of constructing an impedance weight theoretical model based on a distribution network topological structure and branch impedance parameters, respectively calculating photovoltaic impedance products of photovoltaic power supplies and load impedance products of loads, constructing an impedance space integral model based on the impedance weight theoretical model, establishing a mapping relation between node voltage changes and cumulative effects of power on impedance paths, constructing a photovoltaic bearing capacity optimization model by taking minimized photovoltaic waste quantity as an optimization target and taking impedance balance constraint and node voltage safety constraint as conditions, solving the photovoltaic bearing capacity optimization model to obtain an optimal photovoltaic power reduction strategy of the photovoltaic power supplies, and carrying out coordinated control on active power output of the photovoltaic power supplies in the distribution network according to the optimal photovoltaic power reduction strategy.

Inventors

TAN YOUQI
WANG YANQING
YU HAIFENG
LIAO ZHENG
WANG YIFEI
LI YU
QIN KUANG
ZHENG SHUAI

Assignees

国网湖南省电力有限公司
国网湖南省电力有限公司永州供电分公司
国网湖南省电力有限公司经济技术研究院
国家电网有限公司

Dates

Publication Date: 20260508
Application Date: 20260205

Claims (6)

1. The utility model provides a distribution network photovoltaic bearing capacity optimization method based on impedance weight, is applied to the distribution network of high permeability distributed photovoltaic access, its characterized in that, its step includes: S1, constructing an impedance weight theoretical model based on a power distribution network topological structure and branch impedance parameters, and respectively calculating a photovoltaic impedance product of each photovoltaic power supply and a load impedance product of each load for quantifying the weighted influence of photovoltaic output and load power on a power grid impedance path, wherein the photovoltaic impedance product is a product of the injection power of the photovoltaic power supply and an equivalent impedance path between a corresponding photovoltaic grid-connected point and a power supply node, and the equivalent impedance path is obtained by complex accumulation of the impedance of each branch on the path from the grid-connected point to the power supply node; s2, constructing an impedance space integral model based on an impedance weight theoretical model, and establishing a mapping relation between node voltage change and the accumulated effect of power on an impedance path to rapidly characterize the influence of photovoltaic power change on node voltage, wherein the impedance space integral model is established based on approximate expansion of a power flow model of a power distribution network, and rapidly estimating the voltage change quantity of each node by integrating relation of power along the impedance path; S3, taking the minimized photovoltaic light rejection amount as an optimization target, and constructing a photovoltaic bearing capacity optimization model under the limiting conditions of impedance balance constraint and node voltage safety constraint, wherein the impedance balance constraint is constructed based on the sensitivity relation of node voltage to photovoltaic active power output, and the node voltage safety constraint limits that each node voltage of the power distribution network is in a rated voltage allowable deviation range; s4, solving the photovoltaic bearing capacity optimization model to obtain an optimal photovoltaic power reduction strategy of each photovoltaic power supply; and S5, carrying out coordinated control on the active output of each photovoltaic power supply in the power distribution network according to an optimal photovoltaic power reduction strategy.
2. The method for optimizing the photovoltaic bearing capacity of the distribution network based on the impedance weight according to claim 1, wherein in the step S4, when the photovoltaic bearing capacity optimizing model is solved, linearization processing is performed on the photovoltaic bearing capacity optimizing model, the linearization processing is converted into a quadratic programming problem, and an optimal photovoltaic power reduction strategy is obtained by adopting a solving method based on sparse matrix decomposition in combination with the sparse characteristic of the distribution network topology.
3. The method for optimizing the photovoltaic bearing capacity of a distribution network based on impedance weights according to claim 2, wherein the process of converting the model into the quadratic programming problem in step S4 comprises the following steps: Performing first-order taylor expansion on the impedance balance constraint at an initial operation point, and converting the impedance balance constraint into a linear inequality constraint about the photovoltaic power reduction amount P curt ; And using the impedance space integral model to represent a voltage stability term in an objective function as a quadratic form related to P curt , and constructing a standard quadratic programming model: ; ; Wherein the method comprises the steps of Reflecting the economic cost of shaving the reduced photovoltaic output as a linear cost vector; for photovoltaic power reduction vector, the dimension is , Representing the total number of photovoltaic nodes, wherein Q is a semi-positive weight matrix, The method is a constraint coefficient matrix, which comprises an impedance balance constraint and a voltage safety constraint after linearization, b is a constraint boundary vector, Each element in the representation vector satisfies a relationship of less than or equal to.
4. The method for optimizing the photovoltaic bearing capacity of the distribution network based on the impedance weight according to claim 3, wherein the step of obtaining the optimal photovoltaic power reduction strategy based on the sparse matrix decomposition solving method comprises the following steps: constructing a card Lu Shen-Coulomb-Tak KKT linear system based on a power distribution network topological structure: ; wherein A is a constraint matrix of the matrix of constraints, Is a Lagrangian multiplier vector; using the sparsity of the power distribution network topology to carry out sparse Cholesky decomposition or LDL T decomposition on the coefficient matrix of the KKT linear system; Determining matrix ranks of reduced padding elements through symbol analysis, solving the KKT linear system by combining numerical decomposition and previous generation back-substitution operation to obtain an optimal power reduction vector 。
5. An impedance weight-based distribution network photovoltaic bearing capacity optimization system, based on the impedance weight-based distribution network photovoltaic bearing capacity optimization method according to any one of claims 1-4, characterized by comprising: The impedance weight modeling module is used for calculating a light Fu Zukang product and a load impedance product according to the topological structure of the power distribution network and the branch impedance parameters; the impedance space integration module is used for constructing a mapping relation between node voltage change and a power-impedance path; the optimization modeling module is used for constructing an optimization model taking the minimized photovoltaic light rejection amount as a target and taking impedance balance and voltage safety as constraints; The quick solving module is used for converting the optimization model into a quadratic programming problem and solving the quadratic programming problem based on a sparse matrix decomposition method; and the control output module is used for outputting the optimal power reduction strategy of each photovoltaic power supply.
6. The distribution network photovoltaic bearing capacity optimization system based on the impedance weight according to claim 5, wherein the rapid solving module constructs a sparse matrix based on a node-branch association relationship of a power distribution network, and improves the optimization solving efficiency by utilizing the structural characteristics of the sparse matrix; The control output module is in communication connection with the distributed photovoltaic inverter and is used for issuing the optimal power reduction strategy to the corresponding photovoltaic inverter for execution.

Description

Distribution network photovoltaic bearing capacity optimization method and system based on impedance weight Technical Field The invention relates to the technical field of power distribution network planning and operation control, in particular to a power distribution network photovoltaic bearing capacity optimization method and system based on impedance weights. Background With the deep implementation of dual carbon, high-proportion distributed Photovoltaic (PV) access to power distribution networks has become a significant feature of new power systems. However, the randomness and volatility of the distributed photovoltaic output change the operation mode of the unidirectional power flow of the traditional power distribution network, and bring multiple challenges to the planning and operation of the power distribution network: Firstly, in the physical operation level, the space-time mismatch of the photovoltaic major and load low valleys is easy to cause the voltage out-of-limit and the reverse current fluctuation of the terminal nodes, thereby increasing the network loss and threatening the reliability of the protection device. Secondly, at the planning evaluation level, how to precisely quantify the photovoltaic maximum admittance under a specific topology is a prerequisite for guaranteeing the safe operation of the power grid. Finally, on a real-time control level, cooperative optimization of the photovoltaic clusters is urgently needed under a second-level or minute-level scale, so that the absorption rate and the voltage safety are considered. In view of the above-mentioned needs, the prior art proposes various evaluation and control schemes, but the following limitations still exist in practical applications: The physical characteristics are not accurately described, the moment difference analysis-based method focuses on overall power balance, and voltage sensitivity differences of power grid impedance distribution to different access points are ignored, so that an evaluation result is disjointed from an actual physical process. The method based on distributed voltage control often lacks accurate quantification of the impedance weight of the power grid, is difficult to reflect the influence of the electrical distance between nodes on the regulation effect, and is easy to cause insufficient regulation or excessive regulation. The adaptability of the dynamic and complex working conditions is poor, the static analysis method based on the eigenvalue index is dependent on a linearization model, the processing of the dynamic characteristics such as reactive power regulation of the photovoltaic inverter is over-ideal, the risk of instability of the system is very easy to underestimate under the complex operation working conditions, and instantaneous regulation and control cannot be supported. The contradiction between computing timeliness and global optimization is that although the method based on the traditional intelligent search algorithm has global optimization capability, the method faces serious dimension disasters, the computing complexity is high, the convergence is slow, and the severe requirement of real-time operation decisions of the power distribution network on response speed is difficult to meet. Therefore, a method and a system for optimizing the photovoltaic bearing capacity of a distribution network based on impedance weight are needed, so that the impedance physical characteristics of the distribution network can be considered, and the bearing capacity of the distributed photovoltaic can be calculated efficiently and accurately in real time. Disclosure of Invention Aiming at the defects in the prior art, the invention aims to provide a distribution network photovoltaic bearing capacity optimization method and system based on impedance weight, and aims to solve the technical problems of inaccurate evaluation and real-time regulation and control lag of the photovoltaic bearing capacity of a distribution network caused by neglecting impedance characteristics or low calculation efficiency in the prior art. In order to achieve the above objective, in a first aspect, the present invention provides a method for optimizing a photovoltaic load capacity of a distribution network based on impedance weight, which is applied to a distribution network with high-permeability distributed photovoltaic access, and includes the following steps: S1, constructing an impedance weight theoretical model based on a power distribution network topological structure and branch impedance parameters, and respectively calculating a photovoltaic impedance product of each photovoltaic power supply and a load impedance product of each load for quantifying the weighted influence of photovoltaic output and load power on a power grid impedance path; s2, constructing an impedance space integral model based on the impedance weight theoretical model, and establishing a mapping relation between node voltage change and the accum